;> 48783 rECHNOLOGY - VIDEO - STEREO - COMPUTERS - SERVICE UILD THIS I E5LA COIL enerate spectacular displays /ith our solid-state version of classic high-voltage project! UDIO-FORMAT ONFUSION Jetails on Sony's Mini Disc nd Philips' ^igital Compact Cassette UILD OUR IICRO-ANALYZER md start repairing microwave ivens today! UILD A SPECTRUM NALYZER let professional quality for a raction of what you might ixpect to pay HONE-LINE SENTINEL _uild our telephone ne-in-use monitor LECTRIC PHENOMINA ^n intuitive look at ilectromagnetic theory $2.95 U.S. $3.75 CAN ♦ • ' ♦ FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT FLlllK 7 SERIES II 8 New Meters. 8 Old-Fashioned Values. Introducing Fluke's 70 Series II, next- generation multimeters that meet the increasing demands of your job and your budget. Consider. At the top of the line, the new Fluke 79 and 29 deliver more high-performance features - capacitance, frequency, a fast 63- segment bar graph.lo-Ohms range, Smooth- ing™, faster ranges - than DMMs costing much more. At the entry level, the new model 70, Fluke's lowest-priced DMM ever, delivers unparalleled Fluke quality at a price comparable to "dispos- able" meters. And in between are all the models that have made the 70 Series the most popular DMM family in the world - updated, refined and delivering even more value than ever. "BASICS" REDEFINED No matter which 70 Series II you choose, you get simple, one-handed operation. High resolution. And built-in, go anywhere reliability. Automatic Touch Hold® - standard on every model - locks the reading on the display and signals you with a beep, automatically updating for each new measurement without a reset. Leaving you free to concentrate on your work, not on your meter. YOUR BEST CHOIC E Best of all, every 70 Series II is a Fluke, backed by a worldwide service network and an industry- leading 3 year warranty. So the next time you're in the market for a new meter, ask for the one that guarantees old- fashioned value. Fluke 70 Series II. For more information call 1-800-6789-L1T. Or call 1-800-44-FLUKE, ext 33 for the name of your nearest Fluke distributor. CIRCLE 121 ON FREE INFORMATION CARD Fluke 79 Series II & 29 Series II S185" 13011 Count Digital Display (9998 in Hi &-H- ) 63 segment Aialng Bsr G r api 0.3% Basis DC Voltane Accuracy Automatic Touch Hold 1 D ; ods Tesl, Atdible Continuity Beepef Aultjfanoino Mama Ra<"arg Holster with Flei Slarnj Tl Frequency Counter to over ?Q kHz Capac lance 10 pf to 9999uf Lo-0hms Range wiih Zero Calibraliun Smoothing 1M TO Houts Battery tile (ilia rt 3 year Warranty 79/7WS/73/70 lot measurements to 4800 V A. 29ff3<21 lot higher energy measurements 'Flute 70 Series II suggested U_S list p'ices targe 'mtr $63 !c JIBS John Fun Wig Co In: PD BoiSCKM/SISOEElM WA9J2D5U5 . 206 als-HOO Canana4l6-BM-7KW aiflerCDunf.es 2&5.3M-&M CCapyritfit 1931 John flute Mta Co int ah j^his itseved Ad no 00091 Prices and spscir^hans subject to ctwipe FLUKI September 1991as5 'EEtnmics 33 SOLID-STATE TESLA COIL With a 100,000-volt peak output, this Tesla coil can create 8-inch sparks! Duan A. Bylund 40 SPECTRUM ANALYZER This month we give construction details and discuss the software for our PC-based tool. Dan Doberstein and John Cardone 47 BUILD THE MICROANALYZER This instrument makes it easy to repair microwave ovens! David T. Miga, GET 60 PHONE LINE SENTINEL You won't be interrupted by people carelessly picking up an extension if the Sentinel is at work. Daniel B. Cooper tJ^H.'I.IH.IrV 57 AN INTUITIVE LOOK AT ELECTROMAGNETIC THEORY An explanation of electric phenomena William P. Rice 63 AUDIO-FORMAT CONFUSION DAT, DCC, Mini Discs — Where does the future of audio lie? Brian C. Fenton IMiil 6 VIDEO NEWS What's new in this fast- changing field. David Lachenbruch 18 EQUIPMENT REPORTS R.L. Drake R8 world band shortwave receiver, 67 HARDWARE HACKER Phone caller ID, and more, Don Lancaster 74 AUDIO UPDATE Futureproducts. Larry Klein 80 COMPUTER CONNECTIONS MS-DOS 5.0. Jeff Holtzman Vol. 62 No. 9 BUILD THE MICROANALYZER wrt* M* tRHt+vair*" PAGE 47 C3 : I (/> PAGE 63 96 Advertising and Sales Offices 96 Advertising Index 12 Ask RE 16 Letters 83 Market Center 26 New Lit m TO 22 New Products m 4 What's News m to CO O o EC r- o LU o 5 < cc Ever since Nikola Tesla created the first one about a century ago, Tesla coils have been popular proj- ects for electronics hobbyists and students. There are a couple of rea- sons for their continued popularity: One is that they create a dazzling electrical display, and the other is that there is much to be learned about electronics by building a Tesla coil. Our solid-state Tesla coil is dif- ferent from the classic one in that the coupling to the secondary coil is by a direct electrical connection rather than by magnetic fields. It's the same in that it creates a spark as long as 8 inches and makes an ex- cel lent teaching tool. To find out how to build your own solid-state Tesla coil, turn to page 33. »:**.-:i').'" THE OCTOBER ISSUE GOES ON SALE SEPTEMBER 5 BUILD AN ENERGY CONSUMPTION MONITOR Are your electric bills sky-high? Keep tabs on how much your appliances cost to run with the Energy Consumption Meter. BUILD A DIRECT DIGITAL SYNTHESIZER Generate low-distortion sinewaves digitally! BINAURAL BANTER A look at the technique that makes recordings come alive. AN INTUITIVE LOOK AT ELECTROMAGNETIC THEORY Part 3: The magnetic field. As a service to readers, RADIO-ELECTRONICS publishes available plans or information relating to newsworthy products, techniques and scientific and technological developments. Because of possible variances in the quality and condition of materials and workmanship used by readers, RADIO-ELECTRONICS disclaims any responsibility for the safe and proper functioning of reader-built projects based upon or from plans or information published In this magazine. Since some of the equipment and circuitry described in RADIO -ELECTRONICS may relate to or be covered by US- patents, RADIO-ELECTRONICS disclaims any liability for the infringement of such patents by the making, using, or selling of any such equipment or circuitry, and suggests that anyone interested in such projects consult a patent attomey- RADIO-ELECTRONICS. (ISSN 0033-7862) September 1991. Published monthly by Gemsback Publications. Ine .. 500-B Bi- County Boulevard. Farmingdale. NY 11735 Second-Class Postage paid at Farmingdale. NY and additional moiling offices. Second-Class mail registration No, R125166280, authorized at Toronto, Canada- One-year subscription rate U.S.A. and possessions $17-97, Canada $25. 65 (includes G.S.T. Canadian Goods and Services Tax Registration No. R1 25166280). all other countries S26.97. All subscription orders payable in U.S.A. funds only, via international postal money order or check drawn on a U.S.A. bank- Single copies $2-95- c 1991 by Gemsback Publications. Inc. All rights reserved. Printed in USA POSTMASTER: Please send address changes to RADIO-ELECTRONICS, Subscription Depl . Box 55115. Boulder. CO 80321-5115. A stamped self-addressed envelope must accompany all submitted manuscripts and/or artwork or photographs if their return is desired should they he rejected. We disclaim any responsibility for the loss or damage of manuscripts and/or artwork or photographs while in our possession or otherwise. ettillllni ECtrDfJMES Hugo G e msback (1884- 1 967] founder Larry StecMar, EHF. CET. edttor- in -chief and publisher EDITORIAL DEPARTMENT Brian C. Fertton, editor Marc Spiwak, associate editor Kim Dunleavy, assistant technical editor Teri Scoduto, assistant editor Jeffrey K. Hoftzman computer editor Robert Grossblatt. circuits editor Larry Klein, audio editor David L&chenbruch contributing editor Don Lancaster contributing editor Kathy Teronxi. editorial assistant ART DEPARTMENT Andre Duzant, art director Injae Lee, illustrator Russell C. Truelson, illustrator PRODUCTION DEPARTMENT Ruby M. Y*t>, production director Janice Box, editorial production Karen S. Brawn advertising production Marceila Amoroso production assistant CIRCULATION DEPARTMENT Jacqueline P, Cheese bore circulation director Wendy Alanko circulation analyst Theresa Lombardo circulation assistant Michele Torrillo, reprint bookstore Typography by Mates Graphics Cover photo by Diversified Photo Services Radio-Electronics is indexed in Applied Science t Technology Index and Readers Guide to Periodical Liter- ature. Microfilm & Microfiche editions are available. Contact circulation depart- ment for details- Advertising Sales Offices listed on page 00. Radio -Electronics Executive and Administrative Offices 1-5.6-293-3000. Subscriber Customer Service: 1800 2880652. Order Entry for New Subscribers: 1800-999 7139. V^***' Bureau oi G-rcutalion TEST FOR LESS WITH FORDHAM Special Bonus with any order Now Only 195 Rugged & Reliable, •8 Functions •37 Ranges scope Hand Held Digital Multimeters Model DVM-638 Now only w • 11 Functions •38 Ranges •Continuity Beeper • Overload Protection Optional Carrying Case CA-92 $9.95 RD-2110 Radar Detector Yours CJIA95 for only <5><3 m Reg. 109.95 bra' Feature Packed' Contemporary Look' with your order of any item on this page. 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S615.0O Model v-212 Dual Trace •DC to 20 MHz, imVfliv •6" Rectangular Screen PROBES INCLUDED! •- »? i j.6 g_8 8^_ HITACHI Dual Trace Oscilloscope NOW $ 598 00 Best value! Model v-355 •19 Calibrated Sweeps •6" CRT •Auto Focus PROBES INCLUDED! Fordham ?60 Motor Parkway, Hauppauge, New York 11788 ASK FOR YOUR FREE CATALOG TOlL 800-695-4848 FREE flharn 1991 Offers '. -:■ I (iOOi Money orders, checks accepted I fZxyl CQD's require 25% deposit Service & Shipping Charge Schedule Continental U.S.A. FOR ORDERS ADD FOR ORDERS ADD $0-25. $26-50 . $51-100.. $101-200 $201-300 $301-400 S401-5W $4.50 . $6.00 ..$7.50 $900 $10.00 .$12.00 .$14.00 $501-750 $16.00 $751-1,000 $16.00 $1,001-1,250 ...$20.00 $1,251-1,500 ..$22.00 S1.501-2.000 S2750 $2,001 and up.. $35.00 ■ A review of the latest happenings in electronics. CO O o Q < ISCET certifies 30,000th technician When Robert Bruce Bottoms, a computer technician and evening- school engineering major, achieved journeyman-level certification spe- cializing in computers , he became the 30,000th electronics technician to be certified by the International Society of Certified Electronics Technicians (ISCET), Fort Worth, TX. The 28-year- oid United Parcel Service employee has worked in information services, industrial engineering, weight and balance, and programming. Bottoms also served as project technician for the introduction of the delivery infor- mation acquisition device, a hand- held microcomputer that is replacing paperwork for UPS drivers. The computer specialty exam covers the operation of computer systems with an emphasis on hard- ware. Subject areas include basic arithmetic and logic operations as re- lated to computer theory, computer organization, input and output equip- ment, and memory and storage; knowledge of software, program- ming, and troubleshooting is also re- quired. The computer exam, and others offered by ISCET, have be- come the standards by which deal- ers, manufacturers, and government agencies distinguish the most knowl- edgeable technician from the rest. To become a member of ISCET, techni- cians must pass the basic GET exam. Other certification exams are offered by ISCET in such specialty areas as consumer, industrial, communica- tions, FCC Legal, computer, audio, medical, radar, and video electronics. Information about ISCET is available from ISCET, 2708 West Berry Street, Fort Worth, TX 76109. Semiconductor process precisely controls crystal growth An experimental process de- veloped by Bellcore (Red Bank, NJ) has produced aluminum gallium arse- nide crystals that are compositionally ten times more precise than any pre- viously reported. The process offers the first practical method to monitor and control the growth of compound semiconductor alloys — which could significantly increase a manufac- turers' ability to mass produce com- pound semiconductor devices and, in turn, reduce prices. Bellcore's approach uses optical signals to provide information about the chemical development of a crys- tal surface while the crystal is being grown, instead of analyzing crystal growth after the process is complete, as in current fabrication techniques. Ellipsometry, an optical technique that bounces light off a crystal's emerging surfaces, reveals intricate details. Findings are instantaneously fed into a computer and analyzed. Within seconds, the computer uses the information to regulate the flow of materials into the growth chamber, so that small errors in material composi- tions are corrected as they occur. The Bellcore research team calls the sus- tained precision level of 0.1% that they have achieved "an important milestone in the quest for con- sistently perfect' aluminum gallium arsenide crystal structures." BELLCORE RESEARCHER BILL QUINN grows aluminum gallium arsenide crys- tals for use in semiconductor materials and devices, using an experimental pro- cess that corrects small errors in material composition as they occur, resulting in the world's most precise crystals. American technological edge over Japan? According to the results of a Gallup survey reported in the April, 1991 is- sue of IEEE Spectrum, a sampling of U.S. electrical engineers believes that the United States holds a tech- nological edge over Japan in many areas. The report summarizes a sur- vey of a cross section of 150 IEEE (Institute of Electrical and Electronics Engineers) members consisting of 50 each from government, industry, and academia. The survey, commis- sioned by Japan's financial daily pa- per, Nihon KeizaiShimbun, asked the engineers questions regarding areas in which the United States holds the technological edge over Japan now and whether it is likely to in the future. The respondents perceived America to be currently ahead in nine out of twelve areas: space/aviation, medi- cal/pharmaceutical, software, bio- technology workstations, supercom- puters, personal computers, semi- conductorrnicroprocessors. and new industrial material. Japan led in con- sumer electronics, semiconductor memory, and fifth -generation com- puters. A large majority of the engi- neers polled expected the U.S. to maintain its lead in those nine areas, despite some anticipated slipping in biotechnology and fifth-generation computers. Those results contrast with recent studies by the U.S. Department of Commerce and the Council on Com- petitiveness, which suggest that the U.S.'s current lead in technologies will be usurped by Japan by the year 2001 . However, the article points out that some of the discrepancies be- tween studies can be explained by the fact that a technological lead "is not invariably the best indicator of marketplace success." Asked where future technological priorities should be placed, the engi- neers supported the development of natural energy sources (91 %), optical IC's (83%). anti-cancer medication (83%), medication for Alzheimer's disease (80%), one-billion-bit dynam- ic RAM chips (79%), and high-speed surface transportation (79%). R-E Some Breadboards Cost Less Than PROTO-BOARD brand They Should. proto BOARD BRAND At Global Specialties* we make only one kind of breadboard, the very best, PROTO-BOARD* brand. American made and guaranteed for life, Sure, save a few dollars today. ..buy cheap... but remember, you only get what you pay for! Is it really worth it??? Ask yourself... Do they perform like PROTO-BOARD' 1 brand? Are they as reliable? Will they last like a PROTO- BOARD* brand? How can we guarantee PROTO-BOARD* brand breadboard for life unconditionally? Because we control every step right in our New Haven factory, and because we are obsessed with quality. That's why we mold our own plastic and stamp our own precision contacts. We even designed our own machine to assemble each breadboard to exacting stan- dards. Assuring every PROTO-BOARD "brand is built to perfection when it leaves our USA factory backed by our unconditional "Life-Time" guarantee. The others, they arrive from Taiwan. With good reason, they are made cheaper! So next time you consider a cheaper breadboard, think twice. You'll need too, because even after you have worn out your second imported breadboard our PROTO- BOARD ''brand would have still been going strong. PROTO-BOARD 5 brand. The breadboard you only buy once. Now which one really cost less? PROTO-BOARD* brand breadboards and the complete Global ' line of test instruments are in stock at fine electronic distributors everywhere. Can't Wait! Call Toil-Free 1-800-572-1028 GLOBAL SPECIALTIES GLOBAL SPECIALTIES" 70 Fullon Terrace, New Haven, CT 06512 co 1991 I me rplex Electronics All Global Specialties ■ breadboard ing products are made in New Haven Ct. A031 Mnterplex /industries company CIRCLE 190 ON FREE INFORMATION CARD What's new in the fast-changing video industry. mmHHinm Q < • Widescreen TV for U.S. TV sets with the widescreen 16:9 ratio are on sale in Europe, with both Thomson and Philips introducing models (Radio-Electronics. June 1991), but both companies have been reluctant about committing them- selves to introduce a similar product in the United States because of a lack of program material. Now it appears that the Japanese manufacturers have no such hesitancy, and we could see direct-view or projection sets — or both — with 16:9 pictures before the year is over. The first company to commit to in- troducing a widescreen TV set here was JVC, which showed a prototype with a 34-inch tube at the Summer Consumer Electronics Show in Chi- cago. JVC didn't give any marketing date except "soon," but its officials stressed that they were showing an actual production model, not a pro- totype. Like the European wide- screen sets, it will accommodate a number of picture modes and sources. For example, it will show a "letterboxed" movie from tape or disc full-screen and in proper dimen- sion. With a conventional 4:3 picture source, it can magnify the image to full widescreen by cutting off a small portion of the top and bottom, or it can show it as a 4:3 picture leaving part of the screen blank. Under the latter arrangement, it can occupy the unused part of the screen with a group of pictures from other channels ("picture outside picture"). A race may be shaping up in Japan to introduce the first non-HDTV wide- screen TV set, with Toshiba and Mit- subishi said to be ready to introduce sets with 16:9 ratio tubes and Hitachi planning a production model. The the- ory behind the industry's sudden in- terest in widescreen pictures with standard resolution is that even when HDTV comes it will be at least 10 years before it dominates the market, and in the meantime widescreen re- ceivers will become popular as inter- im devices. • LCD projectors. Projection TV sets using liquid crystal devices as shutters are getting better all the time. Sharp has introduced an indus- trial projector with about 650,000 pix- el resolution (at an $8,000 list price) that finally appears to have achieved satisfactory picture quality. No sooner had Sharp's model ap- peared than Philips announced its own model with about the same reso- lution but with many new features. It actually uses the same Sharp-made LCD's, but it will be priced around $6,000-$7,000 and aimed at com- mercial and industrial customers as well as high-end "home theater" buyers, according to Philips. The Philips set, to be made in Hol- land and sold in the United States under the Magnavox brand, is a TV set complete with tuner — unlike other companies' monitor-only sets, which require VCR's or other out- board tuner systems. It employs a Philips-developed metal-halide lamp as its light source. The lamp is user- replaceable, and an extra lamp is packed in the projector. The lamp life is claimed to be 2,000 hours, and the on-screen graphics include a count- down telling the amount of life left in the lamp. When there are only 50 hours to go, a warning signal appears on the screen. The picture projected by the Philips unit may be reversed or turned up- side-down for incorporation in rear- projection systems. An interesting feature is the capability of pointing the wireless remote control at the screen instead of the projector, be- cause of the light collector and ampli- fier built into the unit. The projector, weighing 38 pounds, has a built-in "convenience speaker" as well as a 10-watt-per-channel amplifier for re- mote stereo speakers which can be placed at either side of the screen. In the future, Philips plans a 16:9 wide- screen version, and eventually the company predicts a set about the size of a VCR. Maximum picture size is about 100 inches diagonally. • Trumping Sony's ace. Sony thought it had everything lined up. It was ready to introduce a new CD- ROM-based interactive multimedia format ("Super Disc") and had reached an agreement with Nintendo for Sony to supply hardware that would also be compatible with Nin- tendo's 16-bit Super Nintendo Enter- tainment System (SNES). and presumably Nintendo and its soft- ware licensees would support the Super Disc format with CD-ROM games. But Sony received a major surprise when Nintendo announced it had teamed up with Philips in a deal under which Nintendo will develop software based on the CD-ROM-XA format, which is compatible with Phi- lips' Compact Disc-Interactive (CD-I) Format, and Philips will develop a low- cost CD-ROM-XA drive for SNES. Sony was completely flabbergasted when Nintendo announced that it would not support the Sony system with software, and that "We will not cooperate with Sony." At our dead- line, Sony, Nintendo, and Philips were in intensive negotiations to resolve the three-way dispute. • Dual-deck VCR setback. Go- Video, the Phoenix. AZ company, which sells a dual-deck VCR and which sued many Japanese and Korean manufacturers alleging con- spiracy not to supply it with parts or complete equipment, decisively lost its first round in federal court. Al- though most of the original defen- dants settled with Go-Video to avoid coming to court, Sony, JVC, and Matsushita refused to settle and pre- cipitated a court battle involving a jury trial. Although the trial in Phoenix last- ed two months, the eight-member jury took just three hours to decide that there had been no conspiracy to keep Go-Video out of the dual-deck VCR market, Go-Video, which had sought at least $500 million in damages, said that it would appeal the decision. Meanwhile, the Go-Video VCR-2 dual-deck VCR was reduced in price from its original $1,000 to about $700, and its five-year warranty re- duced to one year. Go-Video Chief Executive Officer Terren Dunlap testi- fied that they sold about 16,000 decks in the first 11 months. R-E Why take chances in today's job market? Graduate as a fully trained electronics professional. To get ahead and stay ahead in today's economy, you need the electronics training CIE has been providing its 150,000-plus successful graduates with for nearly 60 years. Meet the Electronics Specialists. When you pick an electronics school, you're getting ready to invest time and money. And your whole future depends on the education you receive in return. That's why it makes so much sense to go with number one... with the specialists... with CIE! There's no such thing as a bargain education. If you talk to some of our graduates, and we recom- mend you do, chances are you'd find a lot of them shopped around for their training. Not for the lowest priced, hut for the best training available. They pretty much knew what was available when they picked CIE as number one. Because we're specialists we have to stay ahead. At CIE we have a position of leadership to maintain. Here are just a few of the ways we hang onto it- Pro grammed Learning. That's exactly what happens with CIE's Auto- Prog rammed Lessons". Each lesson uses famous "programmed learning" methods to teach you import- ant electronics principles. You explore them, master them completely, before you start to apply them. You thoroughly understand each step before you go on to the next. You learn at your own pace. And, beyond theory, some courses come fully equipped with electronics equipment to actually let you perform hundreds of hands-on experiments. Experienced specialists work closely with yon. Even though you study at home. CIE's faculty and staff stand ready to assist via CIE's toll free number. And. each time you return a completed exam you can be sure it will be reviewed, graded and returned with the appropriate instruc- tional help, you get it fast and in writing from the faculty technical specialist best qualified to answer your question in terms you can understand. Pick the pace that's right tor you. CIE understands people need to learn at their own pace. There's no pressure to keep up. ..no slow learners hold you back. If you're a beginner, you start with the basics. If you already know some electro- nics, you move ahead to your own level. "Same Day" grading cycle. When we receive your lesson, we grade it and mail it back the same day. You find out quickly how well you're doingl State-ol-the-art laboratory equipment. Some courses feature the CIE Microprocessor Training Laboratory. An integral part of computers, microprocessor technology is used in many phases of business, including service and manufacturing industries. The MTL gives you the opportunity to program it and interface it with LED displays, memory devices and switches. You'll gain all the experience needed to work with state-of-the-art equipment of today and tomorrow. Hew Courses! CIE now offers two new career courses: Automotive Electronics and Computer Operation and Programming. CIE otters you an Associate Degree. One of the best credentials you can have in electronics — or any other career field — is a college degree. That's why CIE offers an Associate in Applied Science in Electronics Engineering Technology. And all CIE career courses earn credit toward your degrees. Which CIE training fits you? Beginner? Intermediate? Advanced? CIE home study courses are designed for ambitious people at all entry levels. People who have: No previous electronics knowledge, but do have an interest in it; Some basic knowledge or experience in electronics: In-depth working experience or prior training in electronics. At CIE you start where you fit and feel comfortable where you start, then go on from there to your Diploma, Associate Degree and career! Today is the day. Send now. Fill in and return the postage-paid card attached. If some ambitious person has already removed it, cut out and mail the coupon below. You'll get a FREE CIE school catalog, plus complete informa- tion on independent home study. Mail in the coupon below or, if you prefer, call toll-free 1-800-321-2155 [in Ohio, 1-800-523-9109). I □ YES! I want to get started. Send me my CIE school catalog including details I I AE23 about the Associate Degree program. (For your convenience, CIE will have a representative contact you — there is no obligation.) Prim Name Address — City Age Apt. Area Code/Phone No.(_ State -> — .Zip. I Check box for G.I. Bulletin on Educational Benefits D Veteran O Active Duty warn 1 ///r»rr3^TUTE N s F /^s **&#&**»&. I llllkmZi I I Fl F CTRONICS, INC 3 Tgi T | A class ofoTiS, JTTGEmst tTth Street* CTevetand. OfrtQ441J4*{?16t ?Bh940Q \ ^"^1 £ >/ Since 1934. cc m S CD m 3J SELECT 5 10 * only $4 Allies to « 11n noHS ELECTRONICS FIX-IT BOOK 3414 £39.95 Counis as 2 2S83P SI 8. 95 ElKTROSTATK DISCHARGE PROTECTION 261 3P S17.S5 MJUMIKS MSJKittHli 3107P S18.95 -'—*■—' 1 master IC t(KlKHI»>N 3656P S17.95 THE CIAKT BOUl Of ELECTRONICS PROJECTS MASTTFI w tLCCTHQMIC owDrn Z^ 3329 $29.95 Counts as 2 CO O ^ o £ o a o g 8 Your most complete source for electronics books for over 25 years. An Absolutely No-Risk Guarantee. v *~ ! ^___^_i Membership Benefits * Big Savings, tn addition to this introductory offer, you keep saving substantially with members' prices of up to 50% off the publishers' prices. • Bonus Books. Starting immediately, you will be eligible for our Bonus Book Plan, with savings of up to 80% off publishers' prices. • Club News Bulletins. 15 times per year you will receive the Book Club News, describing all the current selections— mains, alternates, extras— plus bonus offers and special sales, with scores of titles to choose from, * Automatic Order. If you want the Main Selection, do nothing and it will be sent to you automatical- ly. If you prefer another selection, or no book at all, simp- ly indicate your choice on the reply form provided. You will have at least 1 days to decide. As a member, you agree to purchase at least 3 books within the next 12 months and may resign at any time thereafter, * Ironclad No-Risk Guarantee. If not satisfied with your books, return them within 10 days without obligation! • Exceptional Quality. All books are quality publishers' editions especially selected by our Editorial Board. (Publishers' Mens shown) All books are hardcover unless number is followed by a "P" for paperback. ©1991 ELECTRONICS BOOK CLUB, Blue Ridge Summit, PA 17294-0810 im Ei_ECTFm.cs Bqqk Cljb s Blue Ridge Summit, PA 17294-0810 D YES! Please accept my membership in the Electronics Book Club and send (he 5 volumes listed below, billing me $4.95- If not satisfied, I may return the books within ten days without obligation and have my membership cancelled. I agree to purchase at least 3 books at regular Club prices during the next 12 months and may resign any time thereafter. A shippingChandling charge and sales tax will be added to all orders. Name Address City State . . Zip. . Phone Signature ^ Valid for new members only. Foreign applicants will receive special ordering instructions. Canada must remit in U.S. currency. This order subject Id acceptance by tha Electronics Book Club. RE991 03 m -_ -i m <: ru m DO 11 ASK R-E Write to Ask R-E, Radio- Electronics, 500-B Bi-County Blvd., Farmingdale, NY 11735 o z 5 pc t- o —i lU o 5 < SOFTWARE SOLUTION A few months back you an- swered a letter from a reader named T. Waller who wanted a keyboard indicator to show that a Print Screen operation was in progress. Although he asked for a hardware solution, I think a soft- ware solution is better. At first, it would seem as though putting an indicator on the screen during a print-screen operation would mess up the very display you were trying to print. Fortunately IBM uses two bytes for each screen location (one for the dis- played character and the other for the character's attribute) and only the first one is sent to the printer. I wrote a small program, PR_ IND.COM, that modifies the print- screen handler by adding code to the hardware interrupt set up by the ROM BIOS. When my program is run, it goes resident and makes the two bytes in the upper-right corner of the screen go inverse video whenever a Print-Screen operation is taking place. It works on both color and monochrome screens and takes only 416 bytes of memory from DOS. Hardware is okay for a lot of stuff but bit twiddling is better for others. — J. Sprung, San Pedro, CA. I couldn't agree with you more, and 416 bytes is a cheap enough price to avoid having to screw around with hardware that's usually not only un- documented, but probably impossi- ble to deal with as well. In these days of ASIC's (application-specific IC's) and custom silicon, the amount of hardware diddling you can do is pretty limited anyway. I'm putting your source code and the COM file it produces on the RE- BBS (516-293-2283, 1200,2400. 8N1) in a ZIP file called PR_IND.ZIP. Your program works well and is the kind of utility that, after you've used it a bit. you feel should have been a part of the computer in the first place. Congratulations on a nice piece of work. Any reader who wants to use the program (and that should be any reader with a DOS-based computer), can download the ZIP file from the bulletin board. For all those who don't have either a modem or the patience to deal with busy signals, the pro- LISTING 1 JMP 01 5C PUSH DS PUSH AX CS: MOV DS, [0158] XOR BYTE PTR [809D],77 XOR BYTE PTR [809F],77 MOV AH, [009D] MOV AL, [009F] CS: MOV [015A],AX AND AX, 7777 CMP AX, 7070 JZ 0153 MOV AX, 7070 MOV [009D] ,AH MOV [009F],AL PUSHF CALL 0000:0000 CS: MOV DS,[0158] XOR BYTE PTR [809D],77 XOR BYTE PTR [809F],77 CS: MOV AX, [015A] MOV [009D] ,AH MOV [009F] ,AL POP AX POP DS IRET MOV AX, 0707 JMP 0129 ADD [BX+SI+0707] ,DH MOV AX, 3505 INT 21 MOV [0132] ,BX MOV [0134] ,ES MOV DX,0102 MOV AX, 2505 INT 21 MOV DX,015C INT 27 RCX 76 N PS_IND.COM W Q gram can be created with any word processor that has the ability to save ASCII files. Type in the lines exactly as shown in Listing 1, end each line with a carriage return, and be sure to leave a blank line between the INT 27 and RCX near the end of the listing. Save the listing in a file named "IN." When you've done that, you'll need a copy of the DEBUG program that came with DOS to turn the listing into a COM file. Put both the ASCII file you've called "IN" and DEBUG in the same directory and. at the DOS prompt, type "DEBUG " That will produce the program PR IND.COM that you can then run at the DOS prompt or make a permanent part of your AUTOEXEC.BAT file. If you get lots of error indications on the screen after you've run DE- BUG the most likely source of the problem is the file produced by your word processor. In order for DEBUG to take commands from a file (in this case, the "IN" file you just created), each line has to be followed by a car- riage return. When some word pro- cessors write an ASCII file, they include a line feed (OAh) along with each carriage return (ODh). If that's the way your word processor works, you'll have to use a different one to create the file. The program is too down and dirty to check whether it's already resi- dent, so make sure you don't load it more than once. Since it takes only 416 byte of DOS memory, the best way to deal with it all is to automate everything by putting it in your AUTO- EXEC file and forgetting about the program entirely. Remember that the program will work only on the text screen. If you have some TSR that enables you to do a screen dump of a graphics screen, chances are PR IND won't give you an on screen indication that a Screen-Print operation is taking place. LED TROUBLES I'm currently working on a proj- ect that pulses some bright LED's at a frequency of 300 Hz while they're rotating to create a 12 &&* Five ways to look at 100 MHz. Starting at $2295! Just check the choices in our line-up of five 100 MHz oscilloscopes: • GPIB Programmability • Hardcopy Documentation • 100 MS/s Single-shot • Automatic Measurements Name your application, we'll provide the solution. Copyright (B 1991 Tcklrouii, Inc. All rights reserved. BOB- 137- 1 Tek gives you the perfect blend of modem analog real-time and digital technologies in 100 MH? oscilloscopes. Whether it's hardcopy output from a fully programmable real-time scope, automatic measurements specified to .001%, or 100 MHz, 100 MS/s single- shot performance, no one has the CIRCLE 92 ON FREE INFORMATION CARD choices Tek does. To see it all, call your Tek rep or 1-800-426-2200. The closer you look, the more you'll appreciate Tek. I'/.M One company measures up. Tektronix m m 13 Safety, Security, Convenience, Entertainment and Energy Management Home Automation from Heath, the catalog that has it all... Enter the world of Home Automation, Remote lighting and appliance controls. Security alarms and lighting. Automated thermostats. Video monitoring systems. Whole-house security systems. They're all yours in the Heath Home Automation Catalog. To receive your FREE copy, call today toll-free. I-80O44-HEATH (1-800-444-3284) AumATO\i / \ ft IEHH 7!wBnpji ULm:M, gmm US* HI D < 14 Heath Company Marketing Dept. 020-090 Benton Harbor, Ml 49022 CIRCLE 86 ON FREE INFORMATION CARD stroboscopic effect. The circuit is battery powered, remote con- trolled, and uses CMOS 567 tone decoders to toggle a latching re- lay that connects the 300-Hz CMOS 555 oscillator and the LED's to power. Everything works fine until the LED's are con- nected. As soon as they light, it causes a voltage spike that makes the 567's trigger wildly. I've tried using voltage regulators and different sized filter capaci- tors at various points in the cir- cuit but haven't had any luck. The power source is limited to five AA's; is there an answer to this problem that won't cost more than a few milliamps? — D. Do- nofrio, Cleveland, OH The reason that you're having prob- lems with the circuit is that the 567's, and other phase-locked loops as well. all use internal voltage-controlled os- cillators CVCO's) to generate the sig- nals they need for frequency detection. Although they' re pretty im- mune to gradual shifts in the supply voltage, sudden swings usually cause them to lose lock and that plays havoc with their output states. The only way to keep that from happening is to regulate the voltage supply to the chips themselves. The standard solution would be to run them at a lower voltage. Since you'll always have at least six volts available from your five-battery supply, you might try one of the small. "L suffix regulators from National Semicon- ductor to provide a steady supply for the tone decoders. They're packaged in TO-92 type cases, use only a few milliamps. and can easily power the CMOS 567's. Since the key to making your cir- cuit work reliably is to isolate the tone decoders from the current demands of the LED's, you might be able to achieve that by using a resistor/ca- pacitor combination on each of the 567 power inputs. As you can see in Fig. 1 , the resistor isolates the power input to the 567 from the main supply rail. You'll be able to use a fairly large resistor since the CMOS 567's run on flea power. An initial value of about 150 ohms is a good starting point. The capacitor is there to provide an energy reserve when the LED's cause a voltage droop and a good starting value here would be some- where around 100 n.F. If all this fails and the voltage fluc- sv rxaAf &>/£. o — s^v /son. o — I I /SOI. A T£D OSV ro/Z S67' s C /ao/uf /6 V O FIG. 1— TO ISOLATE THE TONE decoders from the LED's you can use a resistor/ capacitor combination on each of the 567 power inputs. The resistor isolates the power input to the 567 from the main sup- ply rail and the capacitor provides an en- ergy reserve when the LED's cause a voltage droop. tuations in the circuit still make the 567's go nuts, you'll have no choice but to try the ultimate solution. It takes some circuit design and a few extra components, but there's no doubt it'll solve your problem. Since the reason you're having the problem in the first place is that 567's are turned on at the same time the LED's are being turned on, you can make the circuit work properly by making sure that the two things never happen together. The 567's should be off when the LED's are on and on only when the LED's are off. The idea of strobing power is a standard way of reducing the power requirements of a circuit. Basically it means you provide power only to the components you need. In your case, I would add circuitry that applies power only to the 567's when the output of the 555 oscillator is low. Since the rest state of your design shows that the 555 has a low output, the 567's would be constantly powered while the relay is open and intermittently powered on when the relay is closed (and the 555 is causing the LED's to light on and off). All you need to make that happen is a single transistor switch with the base controlled by the output of the 555 and the power to the tone de- coders taken from the collector. Since the current requirements of the 567 are so small, you can probably get by with one of the small-signal transistors like the 2N2222 or an equivalent PNP part. Either of the two methods (isolat- ing the 567 supply and strobing the power) may be the answer you're looking For. Try the resistor and ca- pacitor first and, if that doesn't do the trick, try adding the transistor and rewiring the circuit. R-E Afford. Ability In a dc power supply. Now, put a dependable, 30-watt dc power supply on your bench for just $300* You'll get the low noise your work demands (200 uV iTTts). Constant-voltage or constant- current operation. And built-in reliability ensured by conservative design margins and rigorous environmental testing. Outstanding value in a dc power supply. It's just one in a full line of basic Instruments developed by IIP to give you uncompro- mising performance at an affordable price. , To order, call HP DIRECT, 1-800-538-8787, Ext.TW13. We'll ship your order the day it's received. Instruments come with a sixty-day, money-back guarantee. All you need is a HMi VISA company purchase Mi order or credit card. HP 30ivatt power supplies E3610A E3611A I Raege 1 8V, 3A 20V, 1.50A Range 2 15V, 2A 3SV, 0.BSA Load or line regulation Ripple end noise (10 HMO MHzl 0.01% + 2mV 200 ii V rmsG mVp-p There is a better way. mLrJk PACKARD C 1001 llfwtrtl.PwkaiiH-t>.TMNjr>lftVHE CIRCLE 189 ON FREE INFORMATION CARD CO m 15 LETTERS Write to Letters, Radio-Electronics, 500-B Bi-County Blvd., Farmingdale, NY 11735 MULTILAYER SOLUTION I am an electronics technician in the Navy, currently working as an in- structor in the Navy's miniature/ micro-miniature (2M) electronic re- pair program. I read the letter from V. Deeoh. titled "Multilayer Woes." that appeared in the Ask R-E column in the June issue of Radio-Elec- tronics. The repair is possible. In fact, as I write this letter, I have five students in various stages of per- forming such a repair. It requires the use of various dental tools and a ster- eo-zoom microscope. It also requires a large amount of skill and patience. Of course, the damage would have to be isolated before the repair could be attempted, ET1CSW) BRIAN K. FOWLER Norfolk, VA ELECTRONIC COMPASS CORRECTIONS The "Electronic Compass" article (Radio-Electronics, June 1991) caught my attention, since I would like to build a device to measure mag- netic field strengths in the order of Earth's and less. I thought that i might even use part of the compass circuit- ry — until I discovered what looks like a fatal flaw. The article says that the Hall Effect sensors have a nominal 2.5-volt out- put that varies up or down about 1 .3 mV per Gauss, depending on the field direction. Actually, that isn't stated clearly, but is implied and sounds reasonable. Thus, the inputs to resistors R1 and R2 will ideally be identical at 2.5 volts in the east-west orientation. By my concept of ideal op-amps, the voltage at pin 3 of IC2-a is entirely dependent upon the divider R4-R2, and the voltage from IC4 will be about 2.38 V. In an ideal op-amp, the voltage at pin 2 will be the same, g The only way that can happen with z both sensors at 2.5 volts is for pin 1 to § be at zero volts, but the text says the o voltage will be between 2 and 3 volts ij and the rest of the circuit depends ^ upon it being in that range. 5 Next, I built that part of the circuit S using adjustable supplies to replace the sensors. As my theory predicted, the output at pin 1 is near zero (actu- ally 0.052 V) when equal voltages are applied to R1 and R2. 1 have found out from past tests of LM324's that they don't actually go to zero output. Mine are always 50 mV or so positive, and they are also quite nonlinear in gain in that region. I once attempted to use an LM324 as a differential amplifier with inputs quite similar to the com- pass circuit (differing by only milli- volts). I gave it up primarily because of the nonlinear gain with near zero out- put voltage. The text says that the gain of IC2-b is 100, but the resistors used with it give a gain of only 10. Also, the parts list is mixed up for the IC listing. Something is seriously wrong. My lab tests agree with my theory, yet the published circuit apparently works. Please explain, KENNETH E. STONE Cberryvale, KS Mr. Stone s analysis of circuit oper- ation is correct The circuit will oper- ate as published if the quiescent output voltage of IC4 is greater than that oflC3. That will cause pin 1 ofiC2 to assume a positive value and oper- ate with linear circuit gain. In order to force the output of IC2 pin 1 to assume a voltage level be- tween 2 and 3 volts, R4 should be deleted from the circuit. That will cause pins 3, 2. and 1 to assume a nominal voltage of 2.5 volts. The volt- age gain ofiC2-b is 10, as determined by the values of resistors R6and R5. The identification of the IC s specified in the parts list is incorrect IC2 is LM324N, while IC3 and IC4 are the Hall sensors. ANTHONY J. CARISTI PROFITS OR PROGRESS? Forty years ago, the first computer filled a large room, weighted 30 tons, and needed 19,000 vacuum tubes in order to function. Today a desktop computer with silicon chips instead of tubes can do anything the 20-ton di- nosaur did, and do it better. That's progress! If we had the same kind of progress in the automobile industry, today we would be driving around in all-electric cars powered by super batteries or capacitors that can be charged in 10 minutes. Everything in the car would be controlled automatically by solid- state electronics. However, there is not enough profit in trouble-free, non-polluting electric cars. The manufacturers prefer to give us the same old box on wheels that Grandpa drove, with the same old gasoline engine that needs oil changes and antifreeze, tuneups and lots of repairs. The more complicated they can make the car, the more money they make. It's time for something better. Tell your congressman to outlaw the air- polluting, oil-dependent, gasoline- powered automobile, so the man- ufacturers will be forced to give us clean, modern electric cars. The sooner the better, TOM ANDERSON The Electric Automobile Clubs of America Valley Forge, PA HIGH-END HOOPLA I've followed with interest the con- troversy that Larry Klein initiated in Audio Update, in the December 1990 issue of Radio-Electronics with his piece on "transfer functions." After reading John Atkinson's nega- tive response to Klein's points in the March Letters column, I decided to read an issue of Stereophile to get a better handle on the fuss. After so doing, I think that magazine would be better titled (to borrow a phrase from Hunter Thompson) Fear and Loathing on the High-End Trail. A partial list of the things their staff doesn't like in- cludes the following items: The Audio Engineering Society, Stereo Review. audio frequency modulation video re- corders, CD players, and the Voice of Reason. If there is one key issue that sepa- rates high-end aficionados from more sensible audiophiles, it is the impor- tance of frequency response. Aside from such factors as amplifier power and speaker power- hand ling capacity, 16 which determine how loud a system will piay. much research has shown that frequency response alone deter- mines the sonic character of any given component. In 1978, Mark Davis and his colleagues at M.I.T. re- duced speaker differences to just two factors: frequency response and radiation pattern (High Fidelity, March 1980). All the while, high-end advocates skirted the matter of fre- quency response, emphasizing in- stead an endless panorama of strange, often unmeasurable, aura and electrical minutiae. (In addition, since speakers have the highest lin- ear distortion of any component in the chain and since they determine the sound-radiation pattern, they have a much greater effect on a sys- tem's overall sonic quality than any other single component — another fact that high-end proponents seem to anxiously deny!) I personally find it difficult to buy new and expensive components with the hope of obtaining more accurate sound reproduction because I know from experience that I'll be able to equalize the old equipment to sound so much like the new that any residual differences, usually in the bass re- gion, won't justify the expense. TOM GORDON Berkeley, CA USING THE MAGNETIC FIELD METER I was happy to see the "Magnetic Field Meter" project in the April issue of Radio- Electronics. The meter allows a quick (and inexpensive) as- sessment of home and business magnetic-field conditions for those of us who are unwilling to wait for U.S. standards to be established. I have some additional suggestions regard- ing the calibration use of such a coil- based meter. For both calibration and use. the orientation of the coil is critical. The single-coil design is sensitive only to fields in one of three axes. The "right- hand rule" gives the relationship be- tween the direction of field-producing current flow and the orientation of the coil axis for maximum sensitivity. For the calibration technique shown in Fig. 6 of the article, the meter pick-up coil should be at right angles to the current flow, hence parallel to the axis of the transmitting coil. When conducting a survey, the meter coil axis should be oriented No Better Probe Ever at this Price! Shown here Model SP 150 Switchable lx-IOx .... Risetime less than 1.5 nsec. Free prohc guide shows economies] rbptftcemcttU farTeklrnrtix. II-?. Philip* imd nil others • Universal Works with all oscilloscopes • Rugged Flexible cable lasts longer- Replaceable ground lead Economical Substantial savings compared to OEM probes 10 Day Return Policy Guaranteed performance and quality PROBES, INC. TH 9178 Brown Deer Road, San Diego. CA 92121 Toll Free 1-800-368-5719 CIRCLE 123 ON FREE INFORMATION CARD along each of three perpendicular axes and the strongest reading used for analysis. The external coil option would make that easier. The field strength due to monitors and due to unbalanced wiring usually has a strong maximum in one direction. The more expensive, professional meters typically use three perpendicular coils (or three Hall-effect devices) and electronically develop the true maximum field. I would also like to provide some reference points of EMF field strengths to augment the values given in the article. The typical unbal- anced current flow in the center-tap ground of a 240-volt drop to a house is 0-4 amps at 60 Hz. That corre- sponds to a magnetic field of 0-2 u.T (0-20 milliGauss) at 1 inch from the current. The current usually flows down the outside wall of the house and through the cold water pipe along the basement ceiling. The quickest solution to such fields is to move fur- niture such as beds and cribs away from the area so that exposure time is reduced. The current could also be rerouted by an electrician with suit- able copper ground strapping. The new Swedish EMF guidelines for computer monitors (VDT's) are: • 50 cm (20 in.), 5 Hz-2 kHz: 0.25 pT (2.5 mG) • 50 cm (20 in.), 2 kHz-400kHz: 0.025 m-T (0.25 mG) Source: VDTNews, Nov./Dec, 1990 Several manufacturers are now making low-radiation color monitors for the U.S. market, including all IBM's made since September 19S9 and the new NEC 3Ds model. Many monitors exhibit low fields already, and can be tested with the Gaussmeter before purchase, WILLIAM SNYDER Rochester, NY NOBODY'S FOOL I just finished reading the article on making a laser printer out of a monitor and a copier (Radio-Electronics, April 1991). It's a good idea in theory, but in practice you could have a prob- lem. Some copiers will not run with w the lamp removed. If you have that IS problem, you are going to have to m create a path for the lamp voltage to |g "fool" the circuit. 53 RICK SCHWILL - Phoenix, AZ R-E 5 17 nnESMnEnsE R.L. Drake R-8 World Band Shortwave Receiver In our younger days, we never had the means to get the shortwave equipment that we really wanted. Our ham shack and shortwave monitoring setup were functional, and we did reasonably well, consider- ing our non-existent budget. But every visit to a swap meet made our mouths water. And every magazine had advertisements of glorious equipment that we wanted. We knew that one day, we would own a commu- nications receiver from R.L. Drake (P.O. Box 112, Miamisburg, OH 45342). We never got a chance, though. In the early 1980's, Drake dropped communications receivers to pursue the satellite-TV business, where they've done quite well. But now they're back in business with the R8, a world band shortwave receiver re- engineered from the ground up. They couldn't have picked a better time. Shortwave radio was undergo- ing healthy growth in the U.S. even before such dramatic events as the reunification of Germany, the revolu- tion in Romania, and the Persian Gulf war. Even with the instant access to news that we can get through CNN and local all-news stations, people are tuning in to shortwave for some- thing that is sometimes more difficult to find: a diversity of opinion. Al- though broadcast schedules and ad- vanced taping of shows means that the news that you hear on the short- wave bands is often a few hours old, your chances of hearing a fresh per- spective are still pretty good. And the chance of hearing stories not even covered in our news-saturated media is even better. The R8 offers continuous frequen- cy coverage from 100 kHz to 30 MHz, which takes in the thirteen world-ra- dio bands and everything in between. The table-top receiver measures roughly 13x5x13 inches, and weighs about 13 pounds. Although it's not designed for a mobile environ- ment, the R8 does offer a fused 12- volt DC input connector so that you can power the receiver, for example, from the cigarette lighter in your car. R.L Drake is back with a vengence! CIRCLE 10 ON FREE INFORMATION CARD The AC input gives you plenty of op- tions for world-wide operations: 100-, 120-, 200- , and 240-volt operation are supported at 50 or 60 Hz. The front panel is dominated by a large, backlit liquid crystal display. We found it to be difficult to read at sharp- er angles. Head on, however, it's a delight. The seven-digit display pro- vides a tuning resolution of 10 Hz. The front panel isn't as cluttered with controls as many of its com- petitors. That doesn't mean, how- ever, that the R8 is short on features — features that really mean something when you're trying to cap- ture the weak signals in crowded bands. Five receive bandwidths (6, 4, 2.3, 1.8 and 0.5 kHz) are provided. When you select one of the receiver's six modes CAM. FM, CW. RTTY. LSB. and USB) the R8 automatically se- lects an appropriate bandwidth C1.8 kHz for RTTY, for example), but you are free to select another with the touch of a button. For example, if in- terference makes it difficult to intel- ligibly receive AM broadcasts using the 6-kHz bandwidth, you can reduce the setting to cut interference. Synchronous detector One of the inherent "problems" with shortwave reception — re- gardless of the receiver — is signal fading due to propagation distur- bances. To combat fading, the R8 offers a switchable (slow, fast, or off) AGC or automatic gain control. In most cases, the AGC does a good job of keeping the signal listenable. But even with AGC, fading can cause distortion. That's where the R8's syn- chronous detector comes in. A re- ceiver-generated local oscillator, syn- chronized in frequency and phase to the carrier, is used in demodulating the signal. World-band listeners will really appreciate how it can enhance fidelity by reducing distortion. A passband offset control is an- other reception-enhancing feature that deserves mention, it allows you to electronically shift the receiver's IF frequency without disturbing the op- erating frequency! Thus, in many cases, you are able to move interfer- ing signals out of the passband. The synchronous detector and passband-offset capability — along with a tunable notch filter, dual-mode noise blanker, RF preamplifier for boosting signals over 5 MHz, and tone control — all help to dig the tough signals out of the crowded bands. In fact, there's not much more you could ask for. But the R8 doesn't just offer superb reception capability. It also of- fers a host of other features. One hundred memories store not only the frequency of a station, but also the complete receiver setup. Since the memory is stored in EEPROM, there's no need for battery backup. Tuning can be done by direct- frequency entry, tuning the large tun- ing dial (the faster you turn the dial, the faster the frequency shifts), or up and down keys that provide for larger continued on page 82 18 5 sure steps to a fast start as a high-paid computer service technician 1 Choose training that's right for today's good jobs 1992 Good pay, too! 2002 Jobs for computer service technicians will almost double in the next 10 years, according to the latest Department of Labor projections. For you, that means unlimited opportunities for advance- ment, a new career, or even a com- puter service business of your own. But to succeed in computer service today, you need training — complete, practical training that gives you the confidence to service any brand of computer. You need NRI training. Only NRI— the leader in career-building, at-home electronics training for more than 75 years — gives you practical knowledge, hands-on skill, and real-world experience with a powerful 386sx/20 MHz computer you keep. Only NRI gives you everything you need for a fast start as a high- paid computer service technician. 2 ia Go beyond "book learning" to get true hands- on experience NRI knows you learn better by doing. So NRI training works overtime to give you that invaluable practical experience. You first read about the subject, studying diagrams, schematics, and photos that make the subject even clearer. Then you do. You build, examine, remove, test, repair, replace. You discover for yourself the feel of the real thing, the confidence gained only with experience. k A 3 i NEW! 386sx/20 MHz Mini Tower f Computer! Get inside a powerful com- puter system If you really want to get ahead in computer service, you have to get inside a state-of-the-art computer system. That's why NRI now includes the powerful new West Coast 386sx/20 MHz mini tower computer as the centerpiece of your hands-on training. As you build this 1 meg RAM, 32-bit CPU computer from the keyboard up, you actually see lor yourself how each section of your computer works. You assemble and test your computer's "intelligent" keyboard, install the power supply and high-density floppy disk drive, then interface the high- resolution monitor. But that's not all You go on to install a powerful new 40 meg IDE hard disk drive — today's most-wanted computer peripheral— included in your course to dramatically increase the data storage capacity of your computer while giving you lightning-quick data access. Plus, now you train with and keep the latest in diag nostic hardware and software: the R.A.C.E.R. plug-in diagnostic card and QuickTech diagnostic software, both from Ultra-X. Using these state-of-the-art diag- nostic tools, you learn to quickly identify and ser- vice virtually any computer problem on IBM-compat- ible machines. 4. f ■ Make sure you've always got someone to turn to for help Throughout your NRI training, you've got the full support of your personal NRI instructor and the entire NRI technical staff. Always ready to answer your questions and help you if you should hit a snag, your instructors will make you feel as if you're in a classroom of one, giving you as much time and personal attention as you need. 5, Step into a bright new future in computer service— start by sending for your FREE catalog today! Discover for yourself how easy NRI makes it to succeed in computer service. Send today for NRJ's big, full-color catalog describing every aspect of NRI's one-of-a-kind computer training, as well as training in TV/video/audio servicing, telecom- munications, industrial electronics, and other growing high-tech career fields. If the coupon is missing, write to: NRI School of Electronics, McGraw-Hill Continuing Education Center, 4401 Connecticut Avenue. NW, Washington, DC 20008. R.A.C.E.R. and QuickTech are registered trademarks ol Ullra-X, INC, School of Electronics i:nii McGraw-Hill Continuing Education Center 4401 Connecticut Avenue, NW, Washington, DC 20008 [VfcHECK ONE CATALOG ONLY U Microcomputer Servicing □ TV/Video/Audio Servicing D Telecommunications □ Industrial Electronics/ Robotics □ Basic Electronics For career courses approved under Gl Bill [J check for details. D Computer Programming D PC Software Engineering Using C U Desktop Publishing & Design □ Word Processing Home Business O Bookkeeping & Accounting Name . Address City State . .Zip. Accredited Member, National Home Study Council CO m -o CD m J3 to to 21 09 g z o cr P o LU Q < ■T PCX! BUS-EXPANSION CHASSIS. PCXI is a mod- ular, industrial PC, based on a 13-slot passive back- plane. Rapid Systems' PX159I bus-expansion chassis includes a 13-slot ISA (industry standard ar- chitecture) standard back- plane with a 200-watt modular power supply, a single-slot module, one hare expansion card, and front-end cabling needed to extend from the PCXI expansion chassis to any laptop or desktop PC. Using a standard PC with the PX1591, the PCXI chas- sis provides the benefits of FMI/RFI shielding, protec- tion against vibration, and specified industrial cooling through a metal-shielded CIRCLE 16 ON FREE INFORMATION CARD module cover with top and bottom cooling slots. Ap- plications include field ser- vice, ATE development, factory automation, and in- dustrial testing. The PXI59I bus-expan- sion chassis costs $2395 —Rapid Sys- tems, Inc., 433 North 34th Street, Seattle. WA 98103; Phone:206-548-0322; Fax: 206-547-8311. AMATEUR-TV FILTER. Designed for use in ama- teur televisions, the FL-407 Vestigial Sideband Filter from International Crystal Mfg Co. is available in fre- quencies between 420 and 440 MHz. The 6-MHz nom- inal bandwidth and low-loss design are intended for transmitter or receiver use. Two filters can be used for repeater operation. The seven-pole, interdigital de- sign provides excellent sideband suppression and filtering when used alone, or in pairs. Heavy-duty con- struction ensures stable operation and long life. The FL-4 07 measures s! CIRCLE 17 ON FREE INFORMATION CARD 2Vax8 ,3 /i 6 x20 5 /8 inches. N-type connectors are standard. The FL-407 vestigial sideband filter costs $249. — International Crystal Manufactur- ing Company, Inc., P.O. Box 26330, 701 West Sheridan, Oklahoma City, OK 73126-0330; Phone: 800-426-9825 or 405-236-3741; Fax: 405-235-1904. FIELD-SERVICE DMM. Aimed specifically at field- service technicians, the HB70 Series digital multi- meters from Fieldpiece In- struments look and func- tion differently from others on the market. Two profes- sional-grade, heavy-duty meters, which provide only those functions needed most by service techni- cians, feature a single easy-to-use rotary switch for function and range se- lection. Models HB71 and HB73 each have 24 ranges in AC and DC volts, AC and DC amps, and ohms. The model HB73 (pictured) adds six capacitance CIRCLE 18 ON FREE INFORMATION CARD ranges up to 200 |*F, All voltage ranges withstand 1500VDC and 1000VAC; other ranges withstand 500 volts AC or DC. The manual-ranging meters in- clude a dangerous-voltage warning indicator that causes an LCD icon to flash intermittently and a beeper to be activated when a voltage over 28V AC or DC is encountered. All of each meter's ca- pabilities are displayed on the front of the instrument; the one dial is used to choose from the "menu" on the meter's face. The rugged design is shatter-re- sistant and features O-ring seals to protect against contaminants, full 600-volt fusing on all current jacks, and MOV's to protect against transients. The models HB71 and HB73 digital multimeters have suggested list prices of $99 and $109, respec- tively. — Fieldpiece In- struments, Inc.. 832 2 B Artesia Blvd., Buena Park, CA 90621; Phone: 714-992-1239; Fax: 714-992-1239. SOLDERING IRON SPONGE. The Swiss Sponge (named for the cheese, not the country) features multiple holes for improved tip cleaning. The holes trap the solder balls and drop them to the bot- tom of the sponge tray where they belong. Virtual Industries' Swiss Sponge is available in a variety of sizes to fit most makes of soldering-iron sponge trays, A "one-size-fits-all" sponge measures 3.5x4.8 inches and fea- tures patterns matching popular tray sizes so that 22 SM (1 ) Hobby Motor, For robotics and projects. IV2 to 3VDC. About 1*" long. #273-223 99C (2) High-Speed 12VDC Motor. Up to 15,200 RPM. About 2" long (with shaft). #273-255 2.99 Parts Special-Order Hotline. Your local Radio Shack offers a huge selection of electronic components. Plus, we can special- order 10,000 additional items from our main warehouse — ICs, tubes, semiconductors, crystals, phono cartridges and styli, even SAMS* manuals. Service is fast and there is no postage charge, no minimum order. Talking Multimeter, Timesaving speecn output! Take readings without having to glance over at the meter. Press a button on the probe and this meter calls out the reading in clear English while displaying it. Features full autoranging, autopolarity, liquid crys- tal display with taw- battery and over -range indicators, continuity beeper, diode-check mode and 10-megohm input. With leads. #22-164 99.95 m m « . = m»= (1) 4- in -1 Solder! ng Tool . No cords or cylinde rs ! Precision so I de ri ng w herever you need it. Operates anywhere on standard butane lighter fuel. Up to 60 minutes use per lank. Easy to use — refills in just seconds. #64-2161 . . 31.95 Optional Conversion Tips. Available from CMC Special Order "Hotline". (2) Blow Torch. Keeps a steady flame. #64-2169 9.95 (3) Hot Knife. Ideal tor design and repair. #64-2170 9.95 (4) Heat Blower. Puts the heat on for quick drying #64-2169 9,95 o (1) MX (2) W O) (1) Mini Piezo Speaker. Only 1 3, h2"- diameter. Use with IC driv- ers. #273-091 2.49 {2) "Ding-Dong" Chime. Re- quires 6 to 18VDC. #273-071, 8,99 (3) Mini Buzzer. Loud, yet only 7 mA at 12VDC, #273-074 . . , 2.99 E ■— — ■ SENSOR NEW! TV/VCR Remote Control Tester. Senses infrared light from remotes to tell you if they are work- ing. Al so I ocales n ear- i n 1 rared rad i- ation emanating from either LED or laser sources. Pocket size. #276-0099 5.95 ^hmW in (3) r W < 2 ) (4) (SJ XLR Audio Connectors '"■:! Type Cat. No. Each 2 Three-Pin Plug Inline Socket 274-010 274-011 2.99 2.99 3 ■•■ 5 Panel Socket XLR Plug Adapter 1 /*"-Plug Adapter 274-013 274-016 274- 017 3.69 11.99 11.99 Project Battery Holders. (1) 2 "AAA". #270-398 79* (2) 4 "D". #270-389 1.59 (3) 1 "N". #270-405 59« (4) 2 "C". #270-385 1.29 Portable Shortwave Antenna. Pulls in the DX! Great for traveling. Clips over telescoping rod an- tenna. Wire extends up to 23 ft. Dramatically improves reception on worldband portables. #278-1374 8.95 NEW! 25-Pin Female D-Sub Con- nector. Right-angle mounting, de- signed for Experimenter PC/XT Card-Edge Compatible Plug-In Card (at right) to provide standard 25 -pin in put /output port. #276-1504 2.39 NEWI Archer 1 Experimenter's Plug-In Card. PC/XT compatible prototype card for bread boarding digital /analog circuits. Plated through holes, power and ground bus grids, 8-bit 31/62 plated-edge contacts, I/O mounting area for 25-pin d-sub connector (at left). #276-1598 29.95 ID (2) IHI m (1) Hi-Precision 10K-ohm Ther- mistor. #271-110 1.99 (2) 200 Surface-Mount Resis- tors. 5% to I. #271-313, Set 4.99 (3) Pocket Color Guide. Finds re- sistor, capacitor, Inductor values, #271-1210 79« Since 1921 Radio Shack has been the place to obtain up-to-date electronic parts as well as quality tools, test equipment and accessories at low prices. 7000 locations to serve you — NOBODY COMPARES Prices apply at participating Radio Snack stores and dealers. Radio Shack is a division ol Tandy Corporation CIRCLE 78 ON FFiEE INFORMATION CARD .Radio /hack America's technology store m I CD m 2J 23 CIRCLE 19 ON FREE INFORMATION CARD the user can cut it to fit using scissors. Suggested list prices for the Swiss Sponge range from $.75 to $1 .50 each. — Virtual Industries, Inc., 20 Mountview Lane, Unit E, Colorado Springs, CO 80907; Phone: 719-598-1369; Fax: 719-594-0147. SOLDERLESS BREAD- BOARDS. Designed for use by students, hob- byists, and circuit-design engineers, the X-tra Edge solderless breadboards from Chenesko Products feature an extra multi-use edge panel for organizing and mounting components that do not fit into the nor- mal DIP spacing of sol- derless breadboard socket connections. Available in four sizes, each contains a solderless breadboard area that contains both dis- tribution and terminal strips to accommodate all DIP sizes, lead components CO. 3-0. 8mm lead diame- ter), and wire gauge of AWG 20-29 for intercon- necting components. The breadboard contacts, spaced at 0.1 -inch on cen- CIRCLE 20 ON FREE INFORMATION CARD ter, are made of phosphor bronze nickel- plated for re- liable low-resistance con- tacts. Initial contact resis- tance is less than 3 milliohms at 1 kHz C20 C C) and the contacts are rated for a minimum of 10,000 in- out insertions. For easy connecting of external power supplies, four multi- purpose binding posts that accept both standard ba- nana jacks and lead wires are standard on each model. The removable edge panel features a vari- ety of geometric cutouts that allow the panel to hold transistors, stud rectifiers, triacs, SCR s. DIAC's, volt- age regulators, heat sinks, rheostats, switches, buzz- ers, and fuse holders in a variety of package sizes. Models NB-112P (4.3X7.4 inches, 810 tie- points, 61 rows for DIP's), NB-124P(6.5x 7.4 inches, 1620 tie-points, 122 rows for DIP's), NB-134P (7,9 x 7.4 inches, 2230 tie- points. 1 83 rows for DIP's). and NB-I45P (9.7x7.4 inches, 2940 tie-points, 244 rows for DIP's) cost $7.50, $16, $21, and $27, respectively. — Che- nesko Products, Inc., 62 North Coleman Road, Centereach, NY 11720; Phone: 800-221-3516 or 516-736-7977; Fax; 516-732-4650. ELF METER. To measure the strength of potentially harmful magnetic fields generated by AC electrical devices, F.W. Bell has intro- duced the model 4060 ELF (extremely low frequency) meter. Electromagnetic field (EMF) radiation, which is produced by power- transmission lines, com- puters, microwaves, and other electrical appliances, is under investigation by both private and govern- mental agencies for its possible link to cancer, leu- o Q < £ 24 CABLE - TV TUNABLE NOTCH FILTERS • FOR ELIMINATION OF SEVERE INTERFERENCE • FOR "CENSORING" OF ADULT BROADCASTS • 45dB AT CENTER FREQUENCY • ■5-effl AT 2 MHZ FROM CENTER • 2dB INSERTION LOSS MODEL TUNES TO CHANNEL PRICE SHIPPING 23H 2 OR 3 (or 6 meter tern) $30 NO SHIPPING OR C.O.D. CHARGES 46FM 4, 5, OR 6 (or any FM station) $30 713 7,8,9, 10, 11, 12, OR 13 £30 1417 14(A). 15(B), 16(C), OR 17(D) $30 1622 18(E). 19(F), 20(G). 21(H). OR 22(1} $30 3 for $75-10 for $200 - Mix or Match 30 DAY MONEY BACK GUARANTEE (3 FILTER LIMIT) FAST DELIVERY CALL TOLL FREE FOR C.O.D. OR SEND CHECK TO ORDER STAR CIRCUITS P.O. BOX 94917 LAS VEGAS, NV 89193 Call (800) 992-9943 Over 35,000 Electronic Components Call Today for Your FREE SUBSCRIPTION if You Order Today, Try the M-lEctfvmcs bulletin board system (RE-BBS) 516-293-2283 The more you use it the more useful it becomes. Wo support 1200 and 2400 baud operation. Parameters: 8N1 (8 data bits, no parity, 1 stop bit) or 7E1 (7 data bits, even parity, 1 stop bit). Add yourself to our user files tu Increase your access. Communicate with other R-E readers. Leave your comments on R-E with the SYS0P RE-BBS 516-293-2283 CIRCLE 117 ON FREE INFORMATION CARD kemia, and birth defects. The ELF meter can help the user to determine ex- posure levels. The com- CIRCLE 21 ON FREE INFORMATION CARD pact device features a 3'/2- digit LCD readout that indi- cates field strength in ei- ther milliGauss or Gauss (depending on the setting). A single control acts as both an on-off and a high/ low range switch. Readings are taken simply by holding the meter near the source to be measured. The ELF meter has an accuracy of ± 1 % and a resolution of 1 mG or 10 mG. The 4060 ELF meter has a suggested list price of $179— F.W. Bell, Inc., 6120 Hanging Moss Road, Orlando, FL; Phone: 407-678-7308. MINIATURE MICRO- CONTROLLER. Called the Flip Stik because it functions as an expandable microprocessor when plugged in one way and a single-board micro- controller when plugged in the other way. Dallas Semi- conductor's DS2340 ac- cepts software updates via its serial port while it is in the system, with no com- ponent removal required. The Flip Stik is roughly the size of a piece of chewing gum, and consumes very little power. It supports DOS-equivalent operating systems for diskless em- bedded systems, allowing application developments using standard DOS func- tion calls. Thanks to its in- system reconfigurability. an embedded system that in- corporates the Flip Stik can be configured with customized software just before shipping without opening its enclosure. Software upgrades can even be downloaded over the telephone line from a remote PC. The Flip Stik incorpo- rates a V40 micro- processor (software-com- patible with the 8088), up to 256K bytes of non- volatile RAM, and a DS5340 "Softener" chip. That chip "crash-proofs" the microprocessor to safeguard data against power failure. Because the V40 executes the native in- struction set of the PC, programmers can use the CIRCLE 22 ON FREE INFORMATION CARD software base with which they are already familiar: they don't have to learn a new language or buy spe- cial development systems. They can write software for the Flip Stik on their desk- top PC's and later port it to the embedded system. The V40 also provides a serial port, interrupt con- troller, timer-counters, and a DMA controller. The soft- ener chip complements those functions with a clock oscillator, power monitor, watchdog timer, programmable address de- coder, dual-port register file, and parallel I/O ports. The DS2340 Flip Stik costs $54.30 in quantities of 1000— Dallas Semi- conductor, 4401 South Beitwood Parkway, Dallas, TX 75244: Phone: 214-450-0448. R-E Earn Your B.S. Degree in ELECTRONICS or COMPUTERS By Studying at Home Grantham College of Engineering, now in our 4 1st year, is highly ex- perienced in "distance education" — teaching by correspondence — through printed materials, computer materials, fax, and phone. No commuting to class. Study at your own pace, while continuing on your present job. Learn from easy-to- understand but complete and thorough lesson materials, with additional help from our instructors. Our Computer B.S. Degree Pro- gram includes courses in BASIC, PASCAL and C languages — as well as Assembly Language, MS DOS, CADD, Robotics, and much more. Our Electronics B.S. Degree Pro- gram includes courses in Solid-State Circuit Analysis and Design, Control Systems, Analog/ Digital Communica- tions, Microwave Engr, and much more. An important part of being pre- pared to move up is holding the right college degree, and the absolutely neces- sary part is knowing your field. Grantham can help you both ways — to learn more and to earn your degree in the process. Write or phone for our free catalog. Toll free, 1-800-955-2527, or see mailing address below. Accredited by the Accrediting Commission of the National Home Study Council GRANTHAM College of Engineering Grantham College Road Slidell, LA 70460 C/3 m m CD m 3J CO <- tosiosr . .-■ -Z& Kx^ZL ■ T CIRCLE 337 ON FREE INFORMATION CARD cartridges can be. This cat- alog explains alternatives to new cartridges, describ- ing recharged cartridges — in do-it-yourself or full-ser- vice forms — that can be used with the HP LaserJet. LaserJet Plus, and Laser- Jet Series II, IID. IIP and III: Apple LaserWriter, Laser- Writer Plus, and Laser- Writer IINT/IINTX; and many other models. When handled properly, the car- tridges can be cleaned out, modified, and then re- charged with new toner several times before the photoconductive drum in the toner cartridge wears out. This catalog describes three methods of recharge. _ For the handyman, six dif- 8> ferent kits are available with e complete instructions on m how to modify and re- § charge toner cartridges, t For the person who wants ot to start a recharge busi- ness, a complete selection of toner-recharge products are offered at bulk prices. Those include generic toner, graphic toner, spe- cial replacement felt, new fixing rods, sealing strips, plugs labels, tools, clean air, wipes, and vacuums. Detailed assembly instruc- tions are free with pur- chase. For those who lack the time or inclination to do the job themselves, the catalog also details Che- nesko's mail-in service. The first time it is sent in, the cartridge is cleaned, modified, and recharged. The modification allows it to be easily refilled by the customer the second time, by purchasing the replace- ment toner and felt pad. HOW TO AUTOMATE YOUR HOME; by David Gaddis. Home Automa- tion, USA, P.O. Box 22536, Oklahoma City, OK 73123; Phone: 405-840-4751; $29.95. Home automation, which promises better se- curity, convenience, lower operating costs, safety, en- tertainment, and fun, is one of the fastest growing areas of consumer elec- tronics. Encompassing home security, telephone HOW TO AUTOMATE YOUR HOME Ely Dzvki QmkjtM D D ffloo CIRCLE 338 ON FREE INFORMATION CARD and communications sys- tems, audio and video sys- tems, lighting and appli- ance control, and environ- mental (heating, cooling, sprinklers, pools) control, automating a new or exist- ing home requires quite a bit of information and fore- thought. This book con- tains valuable information on some of the most popu- lar present and proposed automation concepts, in- cluding X-10, CEBus rThe E!A's proposed standard, Consumer-Electronics Bus), Smart House, and Echelon. Combining technical in- formation with simple in- stallation requirements and recommendations, step- by-step project directions, and 115 illustrations, the book serves as an installa- tion guide as well as a refer- ence source. Because there are so many varia- tions and possibilities in home automation, the book is designed to pro- vide the information re- quired for readers to make decisions about their own requirements, based on cost, features, expan- dability and goals. Starting with an overall explanation of home auto- mation, the book goes on to detail home wiring re- quirements. The remaining chapters each address a particular part of a home- automation system and in- clude recommendations for basic and expanded systems and subsystems. Materials costs for the projects start as low as $28.00, and many cost less than $200 to install. The book includes $250 of coupons for discounts and free product offers. 1991 TEST EQUIPMENT; from Amprobe Instru- ment, 630 Merrick Road, Lynbrook, NY 11563; Phone: 516-593-5600; Fax: 516-593-5682; free. Amprobe's full-line cata- log contains complete specifications and de- scribe the important fea- tures of its full line of electrical test equipment. Featured in its 48 pages are rotary scale clamp-ons with high-energy protection, digital mini clamp-ons, cir- cuit tracers, true-RMS strip recorders, digital AMPROBE 199? Test Equipment U71W5 ThC .3 WJOMOt M BfCl tViMt, TEST *OLW*«*ir CIRCLE 339 ON FREE INFORMATION CARD megohmmeters, ultrasonic detectors, analog clamp- ons, digital tachometers, pyrometers, and record- ers. Convenient alpha- numeric model listings are provided, as well as color photographs, illustrations, and helpful hints, and sug- gested accessories and replacements. AN INTRODUCTION TO AMATEUR COMMUNI- CATIONS SATELLITES; by A. Pickard. Elec- tronics Technology To- day Inc., P.O. Box 240, Massapequa Park, NY 11762-0240; $9.75, in- (continued on page 30) 26 Learn to Use Your Computer's Full Potential." New Career a Course from i CIE! IT If you've been hesitating about upgrading your computer skills becai.se you couldn't find the time or locate the right program to teach you everything you need to know to be successful in today's world of computers, you'll be happy to hear that CIE's new career course can provide you with the computer technology curriculum you seek in an independent study program you can afford to invest your time in. CIE's COMPUTER OPERATION and PROGRAMMING course was designed and devel- oped by CIE to provide a complete overall under- standing of the unlimited potential today's computers offer, once you learn and discover their full capabili- ties, in today's high tech environment. CIE's new computer course quickly provides you with the electronics fundamentals essential to fully understand and master the computer's technological potentials for your persona! and professional advancement. Upon mastering the fundamentals you will move into high level language programming such as BASIC and C-Language and then use that programming in order to relate the interfacing of electronic hardware circuitry to programming software. As a gradu- ate of the Computer Operation and Programming course, you will be able to successfully understand, analyze, install, troubleshoot, program and maintain the various types of electronic equipment used in business, manufac- turing, and service industries. Since 1934, CIE has been the world leader in home study electronics by providing our 1 50,000- plus graduates with the curriculum and hands-on training they've needed to become successful in today's highly competitive and computer oriented society. As a CIE student you'll receive a first rate education from a faculty and staff with only one desire. Your future success! We encourage you to look, but you won't find a more comprehensive computer course anywhere! And it's a course designed to fit around your lifestyle and commit- ments today, so you can be assured of professional successes and financial gains tomorrow. Please, do yourself a favor and send the attached card or fill out and mail the coupon below for more information about CIE's Computer Operation and Programming course. Do It Computer not included with course 3 YES! I want to get started. Send me my CIE school catalog including details about the Associate Degree program (for your convenience, CIE will have a representative contact you - there is no obligation). Print Name AdJivss City Apt. State . .Zip , Age. Area Code/Phone No*. Check box for G.I. Bulletin on Educational Benefits □ Veteran [CLEVELAND INSTITUTE OF ELECTRONICS, INC. 1776 East 17th Street • Cleveland. Ohio 44114' (216) 78 1 -9400 ////:«£ O Active Duty A, A school of thousands . A class of one. Since 1934. AE24 C/3 m m S en m 21 29 Electmnics, DtfDDUQD APPLIANCE REPAIR HANDBOOKS— 13 volumes by service experts; easy-to- understand diagrams, illustrations. For major appliances (air conditioners, refrigerators, washers, dryers, microwaves, etc.), elec. housewares, personai-care appliances. Basics of solid state, setting up shop, test instruments, $2.65 to $7.90 each. Free brochure APPLIANCE SERVICE, P.O. Box 789, Lombard, IL 60148. (708) 932-9550. CIRCLE 84 ON FREE INFORMATION CARD SIMPLY SNAP THE WAT-50 MINIATURE FM TRANSMITTER on top of a 9v battery and hear every sound in an entire house up to 1 mile away! Adjustable from 70-130 MHZ. Use with any FM radio. Complete kit $29.95 + $1.50 S + H. Free shipping on 2 or more! COD add $4. Call or send VISA, MC, MO. DECO INDUSTRIES, Box 607, Bedford Hills, NY 10507. (914) 232-3878. CIRCLE 127 ON FREE INFORMATION CARD $495 FOR A PROGRAMMABLE DC POWER SUPPLY IS NOW A REALITY! • GPIB Interface Standard • Output Voltage/ Current Programming & Readback • Local & Remote GPIB Operations * Remote Sense Function • Programmable Overvollage and Overcurrent Protection • Software Calibra- tion • Superior Line/Load Regulation • Output Enable/Disable • 3 Year Warranty. FREE Orientation Video available. For de- tails, call: AMERICAN RELIANCE INC. 800-654-9838 FAX: 818-575-0801. CIRCLE 180 ON FREE INFORMATION CARD THE MODEL WTT-20 IS ONLY THE SIZE OF A DIME, yet transmits both sides of a tele- phone conversation to any FM radio with crystal clarity. Telephone line powered - never needs a battery! Up to v* mile range. Adjusta- ble from 70-130 MHZ, Complete kit $29.95 + $1.50 S + H. Free Shipping on 2 or more! COD add $4. Call or send VISA, MC, MO. DECO INDUSTRIES, Box G07, Bedford Hills, NY 10507. (914) 232-3878. CIRCLE 127 ON FREE INFORMATION CARD CABLE TV CONVERTERS AND DE- SCRAMBLERS SB-3 $79.00 TRI-B1 $95.00 MLD-S79.00 M35B $69.00 DRZ-DIC $149.00. Special combos available We ship COD, Quantity discounts. Call for pricing on other products. Dealers wanted, FREE CATA- LOG. We stand behind our products where others fail. One year warranty. ACE PROD- UCTS. P.O. Box 582, Saco, ME 04072 1 (800) 234-0726. CIRCLE 75 ON FREE INFORMATION CARD CALL NOW AND RESERVE YOUR SPACE • 6 x rate $940.00 per each insertion. • Fast reader service cycle. • Short lead time for the placement of ads. • We typeset and layout the ad at no additional charge. Call 516-293-3000 to reserve space. Ask for Arline Fishman. Limited number of pages available. Mail materials to: mini-ADS, RADIO-ELECTRONICS, 500- B Bi-County Blvd., Farmingdale, NY 11735. FAX: 516-293-3315 NEW LIT continued from page 26 eluding shipping and handling (order No. BP290). Unless you work for a major telecommunications company, the space pro- gram, or the military, com- munications and broadcast satellites are normally off limits to you. Even if you own a satellite-TV receiver, you cannot participate in the technical aspects of those communications- satellite systems. There are, however, a large number of amateur com- munications satellites or- biting the earth. Those can be tracked, and their sig- nals received, by ordinary people using relatively in- expensive equipment. This An Introduction to Amateur Communications Satellites CIRCLE 340 ON FREE INFORMATION CARD book describes several systems, how they can be connected to a computer, and how to use them. The decoded signals contain such information as tele- metry data and weather pictures. The book is de- signed to encourage read- ers to become actively involved in receiving and decoding signals from am- ateur communications sat- ellites, using aspects of electronics, engineering. I and science. R-E Now, You Can Eavesdrop On The World. Introducing the new Drake R8 Communications Receiver. It's world class, world band radio, madcin the U.S.A. From Perth to the Persian Gulf, Moscow to Mozambique, local or global, you hear events as they happen with amazing clarity. Since 1943, Drake _._ 1 1 A3 Comniniciiwi KKnuf UfWfB ■-"! HMt - ino« *Un*i rcM« — •> — wore* — ■ . . .. I * t* * » __ . Muficw^^h— J***^" rat — Q—m ■ ■ ^ ^. " v has been setting the standards in electronic communications. . .and then raising them. Today, there's no better shortwave receiver than the Drake R8. Out-Of-This-World Performance. The new Drake R8 has more standard features than other shortwave radios. You get wide frequency range (100 KHz to 30,000 KHz), coverage of all world and local bands, and excellent dynamic range. But you also get important features you won't find on receivers costing hundreds of dollars more. A multi- voltage power supply. Pre-amp and attenuator. Five filter bandwidths and synchronous detector. Dual mode noise blanker and passband offset. Non- volatile 100 channel memory. All designed to give you the best reception with the least distortion. Down-To-Earth Design. The ergonomic design of the R8 gives you real ease of operation. You have convenient keypad entry, with large, legible controls. The face is bold. Uncluttered. And the liquid crystal display (LCD) is backlighted for easy reading. Try The R8. . . At Our Risk. If you're not impressed by Drake's quality, performance and ease of operation, return the R8 Receiver within 15 days and we'll refund your money in full, less our original shipping charge. For more information, or to order, call TOLL-FREE, 1-800-9-DRAKE-l. Telephone orders may be placed on a major credit card. $979.00 (Shipping and handling $10 in continental U.S. Ohio residents add 6>/2% tax.) Call TOLL-FREE, 1-800-9-DRAKE-l today. You can't lose. DRAKE In touch with the world. R.L. Drake Company ■ P.O. Box 3006 • Miamisburg, Ohio 45342 U.S.A. CIRCLE 177 ON FREE INFORMATION CARD 48 HOUR SHIPPING ELENCO & HITACHI PRODUCTS AT DISCOUNT PRICES 48 HOUR SHIPPING Hitachi RSO Series {Portable Real-lime Digital Storage Oscilloscopes) VC-6023 - 20 MHz, 20MSrs $99/mo* $120/ mg* $ 1 35/rr «/ $125Ano- $200/mo* VC-6024 - 50 MHz, 20MS/S _ VC-0025 • GOMHz, 20MG/s_ VC-6045 ■ 100MHz. 40MS/S LEASING AVAILABLE For all Hitachi Scope* - Call for dslalli ■ Based on 24 months except V-1 150, VC-EM5, VC- 6145 (36 months) VC-6145 ■ 100MHz, 100MS/S RSO's from Hltectrl leature noil mode, averaging, save memory, smoothing, interpolation, pretriggering, cursor measurements. These scopes enable more accurate, simplier observation of complex waveforms, in addition to such functions as harccopy via a plotter interface and waveform transfer via the RS-232C interface. Enjoy (he comfort ol analog and the powar to digital. 20MHz Elenco Oscilloscope $375 M 0-1251 * Dual Trace Componanl Tesier • «■ CRT • X-Y Operalion • TV Sync • 2 P-1 Probes Hitachi Portable Scopes DC to SQMHz, 2-Channet. DC offset func- tion, Alternate magnifier function V-52S - CRT Readout, Cursor Meas. _ *1.025 V-523 - Delayed Sweep . $995 V-522 - Basic Model $895 V-422 - 40MHz $795 V-223 - 2QMhz delayed sweep $695 V-212 - 20MHz $425 HITACHI COMPACT SERIES SCOPES This series provides many new functions such as CRT Readout. Cursor measurements [V-10S5/1065V665), Fre- quency Ctr (V-1 035), Sweeptime Auforanging, Delayed sweep arid Tripper LocH using a 6-Inch CRT, You don' t feel the compactness in terms of performance and ope ration. V-660 ■ 60MHz, Dual Trace V-665 - 60MHz, DT, w/eursor V-1 060- 100MHz. Dual Trace V-1 065- 100MHz. DT, w/cursor_ V-10B5 - 100MHz. QT. wteursorl V-1 1 0OA - 100MHz. Quad Trace_ V-1 150 - 150MHz. Quad Trace $1,195 "$1,345 _$ 1.425 _$105/mo* _$125/mo- _S12o7mo' _$115^mo- Elenco 35MHz Dual Trace 50MHz D**33 MO- 1252 • High luminance 6' CRT ■ 1 mV Sensitivity « 6KV Acceleration Voltage • 1 0ns Rise Time • X-Y Operalion • 1 Axis • Delayed Triggering Sweep • Includes 2 P-1 Probes All scopes include probes, schematics, operators manual and 3 year (2 yrs for Elenco scopes) world wide warranty on parts * labor. Many accessories available for all Hitachi scopes. Call or write for complete specifications on these and many other fine oscilloscopes. FREE DMM with purchase of ANY SCOPE SCOPE PROBES P-1 65MHz, ix, lOx $19.95 P-2 100MHz, Ix, lOx $26.95 B + K TEST EQUIPMENT All Models Available Call for special price Digital Capacitance Meter CM-1550B $58.95 9 Ranges ,1pl-20,000utd .5% basic accy. 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Squariwavi'lDirnt ■ FiKfJffftcy adi-j^arjln *\ I vd rOADIl ■mm 1 ID 10CKHZ • FlfHtlrrjqirtnciri^iiiM * Amplbid* KKM • DCaflM > Modulation FM-AM DIGITAL - SECTION ■ Eijtt data. r**cft« ♦ TWO nrj bWrftM bcjc IrirtCrhM * EqN LEO '*aowi * TTL Ojirgr^ ♦ C*x* ftrtqutfCy T w l WKHZ ■ Clock 1/TrfifuM SVPF* tqniit wi>* BREADBOARDS (VU t* poutf ItEtal 1.6B0I C & S SALES INC. K' 1245 Rosi!\vooa.rieerfielrL II. 60015 L — =^ 1800)292-771] 1708) 541-0710 15 Day Money Back Guarantee 2 Year Warranty ?,Ka subject w change WRITE FOR FREE CATALOG CIRCLE 109 ON FFtEE INFORMATION CARD Our solid-state Teste coil can produce sparks as long as 8 inches with a peak output of about 100,000 volts. SOLID STATE LA COIL DUANE A BYLUND Tesla coils have been around for almost 100 years and, with the exception of vacuum-tube driven coils, not much has changed from the way Nikola Tesla invented them. This article describes a new type of Tesla coil; a true solid-state Tesla coil. One thing that makes our Tesla coll unusual is that the coupling to the secondary coil is by a direct electrical connection rather than by magnetic fields. Direct coupling is not new to Tesla coils but it is seldom seen. The solid-state Tesla coil is by no means as spectacular as capacitive- discharge Tesla coils but it gives just as good, or better, performance as a vacuum-tube Tesla coil. Sparks as long as 8 inches are possible with a power-line consumption of 2 amps at 120 volts (see Fig. 1). and the output reaches a peak of about 100,000 volts. Although the average power in- put to the device is around 250 to 300 watts, the peak input power to the Tesla secondary coil is about 800 watts. The Tesla coil is an excellent teaching tool, as many interesting things may be learned with the aid of this device. Circuit description The schematic for the solid-state Tesla coil is shown in Fig. 2. The sec- ondary of the Tesla coil, when directly driven by a solid-state driver, appears like a series RLC circuit. That's due to the self-capacitance of the coil with respect to ground. The capacitance is normally very small with the induc- tance being fairly large. At the reso- nant frequency, the inductive reac- tance cancels the capacitive reac- tance. The effective impedance is limited by such losses as the DC re- sistance of the coil, AC skin effect of m TJ H m no m 33 CO o z O ir F o LU I UJ 6 Q < the wire, eddy currents induced in nearby objects by the field of the coil, and so on. Series RLC circuits have rela- tively low impedances when oper- ated at the resonant frequency. The coil used in this project, when operated at its resonant fre- quency, looks tike a 450-ohm re- sistive load to the solid-state driver. Series RLC circuits pro- duce high voltages on the induc- tor and capacitor at the resonant frequency. The high voltage is due to a high current flowing through a high reactance (re- member that the inductance is large and the capacitance is small, creating large reactances in each component at a given fre- quency). That is what produces the corona discharge at the end of the secondary coil. The heart of the driver is IC1. the SG3524 pulse-width modu- lator. The duty cycle is fixed at about 45 % for best efficiency. The frequency is controlled by the re- sistance on pin 6 and the capaci- tance on pin 7. With the values shown, the frequency has a range from 200 to 240 kHz. A flip- flop inside the chip divides that by 2 so that the effective output of the driver has a range from 100 to 120 kHz. The outputs on pins 12 and 13 are 180 degrees out of phase with Warning!! This article deals with and involves subject matter and the use of materials and substances that may be hazardous to health and life. Do not at- tempt to implement or use the information contained herein, unless you are experi- enced and skilled with respect to such subject matter, materials, and sub- stances. Neither the publisher nor the au- thor make any representation as for the completeness or accuracy of the informa- tion contained herein, and disclaim any liability for damages or injuries, whether caused by or arising from the lack of com- pleteness, inaccuracies of the informa- tion, misrepresentations of the directions, misapplication of the information, or other- wise. each other, and drive the gates of MOSFETs Ql and Q2, which, in turn, drive the primary of trans- former Tl. Transformer Tl drives the bases of switching-tran- sistors Q3 and Q4. The compo- nents in the base circuitry are used to increase the switching speed of the transistors. Tran- sistors Q3 and Q4 switch the line voltage across the primary of T2, which increases the voltage and drives the end of the secondary coil directly. Note that the line voltage delivered to T2 is half- wave rectified by Dl. That is im- portant to the operation of the Tesla coil because a pulsating voltage is needed to produce the best effects. When the device is plugged into a wall receptacle it will be in its standby mode. That is, the 21- volt power supply will be opera- tional and the FETs will be driv- ing the primary of Tl. The standby mode produces enough power to "tune" the driver to the coil's resonant frequency before full power is applied. (Remember that the resonant frequency can be affected by nearby objects.) The current supplied to the sec- ondary coil is indicated by LED1. Tuning is accomplished by ad- justing the frequency via Rl and observing LED1. When reso- nance is achieved, the secondary coil will have a low impedance which will produce maximum current, lighting the LED. Di- odes D3-D6 limit the forward and reverse voltages on LED1 when in the high -power mode. (Note that you must use an LED that lights at 1.5 volts — some LED's, including most green ones, need 2.1 volts or higher. When the device is switched into the operating mode (or the high-power mode), half-wave line-voltage pulses will be applied to the primary of T2. As the half- wave voltage increases, the cur- rent in the secondary coil in- creases and the energy stored in the inductance and capacitance of the secondary coil will in- crease. During this time there is no corona from the secondary coil (if the coil is constructed as shown in this article). Sometime before the half-wave line voltage reaches its peak, the corona will appear on the secondary coil, which will dissipate the stored energy very quickly. During the remainder of the half-wave line voltage, the coil will produce cor- ona but the energy level will not be as great as the initial dis- charge. The coil will produce six- ty individual corona discharges every second, although you'il see a continuous discharge. FIG. 1— THE SOLID-STATE TESLA COIL can produce sparks as long as 8 inches. The output reaches a peak of about 100,000 volts. USE THIS FOIL PATTERN, shown half-size, to etch your own PC board. 34 FIG. 2— SCHEMATIC FOR THE SOLID-STATE TESLA COIL. The secondary of the Tesla coil appears like a series RLC circuit due to the sell- capacitance of the coil with respect to ground. All resistors are Vi-watt, 5%, un- less otherwise indicated. R1— 1000 ohms, 10-turn potentiometer R2— 3900 ohms R3, R4—2200 ohms, Vz watt R5, R6— 2200 ohms R7— 330 ohms, 1 watt R8, R9— 0.56 ohms, 2 watts, flameproof R10, R11— 3300 ohms Capacitors CI— 0.001 jiF, 50 volts, 5%, polyester C2 — 110 pF, 50 volts, polyester C3, C4— 10 p.R 35 volts, tantalum C5— 330 |xF, 35 volts, electrolytic C6, C7— 2 m-F. 200 volts, nonpolar film-type C8, C9— 0.02 ^R 1000 volts, ceramic disc Semiconductors IC1 — SG3524 pulse-width modulator D1— MR751 diode D2-D6— 1N4934 diode D7, D8—1N4936 diode D9 — not used D10-D17— 1N4004 diode Q1 . Q2— SK9155 power MOSFET PARTS LIST Q3, Q4— 2N6678 or SK9140 NPN transistor LED1— red LED. See text Other components F1 — 3-amp, 250-volt, fast-blow fuse BR1— VM08 bridge rectifier, Varo T1 — hand-made transformer (the core is TDK # PC30EER25.5-Z and the bobbin is TDK # BEER-25.5-118CP) T2 — hand-made transformer (the core is TDK # PC30EC70-Z and the bobbin is TDK # BEC-70-5116) T3 — hand-made transformer (the core is TDK # PC30EER25.5-Z and the bobbin is TDK # BEER-25.5-118CP) T4— 11 5VAC/15VAC center-tapped transformer (Triad F-132P) S1— SPST key switch Miscellaneous: enclosure, alumi- num angle bracket, high-voltage wire {to connect main unit to Tesia secondary), 30-gauge magnet wire for Tesla secondary and L1 and L2. 24-gauge magnet wire for L3 and L4, 18-gauge stranded hook-up wire for L5 and L6, 15-gauge mag- net wire for T2 primary, 26-gauge hook-up wire for T2 secondary, 18- gauge magnet wire for both wind- ings of T3, brass rod. discharge ball, hardware, AC linecord, etc. Note: TDK ferrite cores and bob- bins are available from MH&W International, 14 Leighton Place, Mahwah, NJ 07430, (201) 891-8800. The following items are available from Corona Coil, PO Box 474. Riverton, UT 84065: • T1— $15.00 T2— $38.00 T3— $12.00 T4— $14.00 Tesla secondary coil— S50.00 PC board— $15.00 Aluminum angle bracket (heatsink and PC-board mount) — $5.00 A 124-page book by the author. Modern Tesla Coil Theory, is available for $16. Please add S15 S&H tor the Tesla secondary, and 10% S&H for all other items. W s Co — 35 TESLA SECONDARY FIG, 3— PARTS-PLACEMENT DIAGRAM. It's best to play it safe and use the PC this project; we've provided the toil pattern it you would tike to etch your own board for board. Construction Most of the construction is fair- ly simple if the printed circuit board is used. A parts-placement diagram is shown in Fig. 3, and we've provided the foil pattern if you would like to etch your own board. Figure 4 shows the com- pleted prototype board housed in its aluminum enclosure. The most difficult item to con- struct will be the Tesla secondary coil, followed bv Tl and T2. The secondary coil may take an hour or so to make if you prepare ahead of time. Preparation in- cludes making some device that will easily rotate the coil form while winding the wire. The au- thor used a small lathe and it look about 15 minutes of actual winding time and 30 minutes to get set up. Do not deviate at all from the following parameters of the sec- ondary coil! Any deviation will (0 o z o rn & LU _i LU 6 q a x FIG. 4— HERE'S THE AUTHOR'S COMPLETED PROTOTYPE housed in its aluminum enclosure. It's important that the case be properly grounded. change the characteristics of the coil and it may not operate with the driver unless modifications in the driver are made. Any change in physical dimensions or wire size will alter the resonant frequency and effective imped- ance of the coil. Any change to the discharge electrode will effect the maximum energy obtainable. The coil form for the secondary winding is a standard 5-gallon plastic container 10 inches in di- ameter at the bottom, 12 inches in diameter at the top, and 14 inches long. The bottom of the container becomes the top of the coil. To make winding easier you should drill a hole about an inch in diameter through the center of the bottom of the container. A similar hole should be drilled through a removable lid and then the complete coil form can be ro- tated easily on a dowel. Start the secondary winding 1 inch from the small-diameter end and close-wind 30-gauge magnet wire for a total length of 10 inches. It does not matter what direction the wire is wound in. When winding the original coil for this article, shellac was used to lubricate the wire as it was wound and also to act as a sea- lant afterwards. It was difficult to wind the coil because the coil form was very slick and had a slight taper to it and, as a result, the wire kept slipping. It may be easier to spray the container with adhesive before winding the wire to make it stay in place. A couple of coats of shellac should be ap- plied to the finished winding. You also must put 3 or 4 beads of sil- icone sealant around the end of the winding at the top of the coil to keep corona discharges away from the area. If corona dis- charges appear along the coil at the top it will limit the maximum energy and destroy the coil form. The discharge ball, or elec- trode, is a brass-plated metal doorknob, 1-inch in diameter, that can be found in hardware stores (see Fig. 5). The ball is mounted on a 4-inch brass rod; you can drill and tap the ends of the brass rod with a 6-32 tap (or whatever matches the threading on the doorknob) to make mounting easier. The brass rod is connected to the coil form by two pieces of plastic, one on each side of the coil form, over the '/2-inch 36 FIG. 5— THE DISCHARGE BALL is a brass-plated metal doorknob, 1-inch in diameter. The ball is mounted on a 4-inch brass rod that's been tapped to make mounting the ball easier. hole. A 6-32 screw passes through the pieces of plastic and into the brass rod to hold the as- sembly together. The wire is sol- dered to a lug held in place by the 6-32 screw. A banana jack is used to make connections at the bottom of the coil. Locate the jack about 3 A- inch from the edge of the wire on the coil. Silicone should be used to insulate the connections be- tween the magnet wire and the brass rod and banana jack. The finished coil, when built exactly as we've shown, will have a reso- nant frequency of about 110 kHz. Transformer Tl is made with a ferrite core and bobbin from TDK (see the parts list). Coils LI and L2 are wound first with 30-gauge magnet wire. 16 turns each, making one layer on the bobbin. The two windings are bifilar wound, as shown in Fig. 6-a; LI starts on pin 3 and L2 starts on pin 4. Wind both in a coun- terclockwise direction while look- ing at the top of the bobbin. Terminate LI on pin 1 and termi- nate L2 on pin 2. Put a layer of cellophane tape on top of the winding to insulate it from L3 and L4. Coils L3 and L4 are made with 5 turns each of 24-gauge magnet wire and are also bifilar wound, on top of LI and L2, and in the same direction. Coil L3 starts on pin 6 and L4 starts on pin 8. Ter- minate L3 on pin 5 and terminate L4 on pin 7. This completes the transformer until it is mounted on the PC board. Put the two core halves through the bobbin and put tape around them to hold them in place. As shown in Fig. 6, L5 and L6 are wound after the trans- former is mounted on the board; L5 and L6 are wound with 18- gauge stranded hook-up wire with one turn each. Solder the collector (Q4) end of L6 to the PC board. Go one turn in a coun- terclockwise direction around the core of Tl and then terminate the other end of L6 at the primary of T2. Solder the collector (Q3) end of L5 to the PC board and go in a clockwise direction around the core of Tl for one turn, termi- nating the winding at the cath- ode of Dl. Transformer T2 is also made from a ferrite core and bobbin from TDK (again, see the parts list). The primary is 10 turns of 15-gauge magnet wire, although a smaller gauge, say 18, can prob- ably be used. It does not matter what direction the wire is wound in but the turns should be equal- ly spaced across one layer of the bobbin. Put several layers of cel- lophane tape on top of the pri- mary to insulate it from the secondary and to provide a smooth surface on which to wind the secondary. The secondary is made with 280 turns (the exact number is not critical) of 26- gauge hook-up wire. The direc- tion is unimportant. You can use magnet wire if you desire but you should put cellophane tape be- tween each layer. The low-voltage end of the secondary is the one that is the closest to the primary winding. When the windings are complete, put the core halves through the bobbin and hold them in place with tape wrapped around them. Transformer T3 is made with the same core and bobbin as Tl. Both windings are bifilar with 18- gauge magnet wire for as many turns as possible. The start of both windings are polarized as indicated by a dot in the sche- matic diagram (Fig. 2). The pins on the bobbin are not used and should therefore be cut off, and the 18-gauge wires are then sol- dered directly to the PC board as indicated. An aluminum angle bracket is used when mounting switching- « transistors Q3 and Q4. The tj bracket provides the physical rn support between the PC board cd and enclosure and also provides 3 good heat sinking for the tran- ^ sistors. The transistors should iS 37 FIG. 6— TRANSFORMER T1 IS MADE by winding coils L1 and L2 first {a). After putting a layer of cellophane tape on top of the first windings, coils L3 and L4 are wound on top of L1 and L2. Coils L5 and L6 are wound after the transformer is mounted on the board (b). See text for detailed instructions. be insulated from the aluminum; Insulating hardware is normally included when you purchase the transistors. Use the PC board as a template for drilling holes for the transistors in the aluminum bracket. The angle bracket is mounted to the enclosure by dril- ling holes and taping them with a 6-32 tap. Thermal conductive O z o o W Q Q < II FIG. 7— SEEN HERE IS THE DISCHARGE from the ball electrode into the air. compound is used between the transistors and angle bracket and between the angle bracket and the enclosure. A banana jack is mounted in the back of the enclosure to make connections between the Tesla secondary coil and the high- volt- age ferrite transformer. The out- put voltage from the ferrite transformer may reach 5000 volts peak with no load so it is wise to use extra insulation for the banana jack. Mount a piece of plastic, IVi-inch square, to the back of the enclosure over a 1- inch square hole, and rnotmt the banana jack in the center of the plastic. That will space the ba- nana jack at least l /a-inch from the metal enclosure. The prototype used a 10-turn potentiometer for Rl to make fre- quency adjustments easier and this allowed the use of a 10-turn dial to mark the frequency set- tings for different purposes. You can use a regular potentiometer but the 10-turn unit is superior. An enclosure was fabricated out of Vs-inch aluminum with a plexiglass top, but any metal en- closure would be suitable. Just be absolutely sure that you ground the metal enclosure. Operation Warning: The power output from the Tesla coil is dangerous! Make sure no one comes in con- tact with the output voltage di- rectly from the driver. Make sure nobody tampers with the unit, and keep it out of reach of chil- dren. Make sure you use a key FIG, 8— THE SPARKS WILL JUMP even farther if a grounded electrode is placed near the discharge ball. 38 switch to turn power on and off to prevent someone from getting in- jured, and keep the key in a safe place. Caution: All components on the secondary of Tl are not iso- lated from the power line. Use caution when measuring values in this area. You must isolate an oscilloscope from ground if mea- suring in this area. Make sure you use a three-prong power cord and that the case of the driver is well grounded. Also, make sure you plug the unit into a well- grounded electrical outlet. Double check all wiring to make sure it is correct. Make sure the operate switch is in the standby position (line voltage disconnected from Dl). Using a digital voltmeter isolated from ground, measure the voltage across C3 and C4. If everything is working correctly in the low-volt- age circuitry, there should be about 2.5 volts across those ca- pacitors. If that voltage is not present you should check the 21- volt power supply. Make sure that 5 volts is on pin 16 of IC1. If the oscillator is working correctly you should have about 3.6 volts on pin 6 of IC1. Connect the Tesla secondary coil to the driver with a 3-foot insulated wire (it is a good idea to keep at least 3 feet from the sec- ondary coil). You should always unplug the driver when you are making connections between the driver and secondary coil to be absolutely safe. The wire con- necting the coil and driver car- ries a dangerous amount of power so be certain the wire is well insulated. In a dimly lit room you should be able to adjust the tune control to set the driver at the coil's resonant frequency. Ob- serve the LED and watch for one place in the tuning control's ad- justment where the LED glows brighter than anywhere else. Never apply full power to the driv- er unless you can obtain reso- nance first. Damage to the driver will most likely occur if reso- nance is not maintained. Once you obtain resonance you can switch to the full-power mode; the LED will glow very brightly. With no objects around the coil you should observe a snappy brush discharge 5 to 6 inches in length emanating from the discharge electrode (see Fig. 7). It might be somewhat louder than you would expect. Very slight adjustments in the tune control may improve the dis- charge. You should be able to get 7-Inch streamers with a grounded electrode above the coil (see Fig. 8). Be aware that any change of the physical surround- ings around the coil will change its resonant frequency and the tune control will need to be ad- justed to maintain resonance. When operating the Tesla coil, be aware of the temperature of the enclosure where the aluminum angle bracket is mounted. Shut off the power if the area gets too warm. The prototype was oper- ated for 2 full minutes, and you could just start to feel some warmth on the enclosure. How- ever, you should operate the Tesla coil only for short periods of time. Once you have a working unit you can start to experiment with different things. Try removing the discharge ball and use a point instead. Try changing the dis- tance of the ball electrode from the coil. Try holding an incandes- cent lamp a short distance from the coil — but be very careful. Dif- ferent lamps will produce dif- ferent discharges. r-e * FCC NO-CODE ' AMATEUR RADIO LICENSE The FCC recently passed Docket 90- 55 which for the first time allows a new codetess entry ham radio license of technician grade. Privileges 30 MHz and above — All modes! (See R.E. ar- ticle in April 1991 issue). 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Through this Special Program you can pull all of the loose ends of your electronics background together and earn your B.S.E.E. Degree. Up- grade your status and pay to the Engineering Level. Advance Rapidly! Many finish in 12 months or less. Students and graduates in all 50 States and throughout the World. Established Over 40 Yearsl Write tor free Descriptive Lit- erature. GI 4251 CYPRESS DRIVE JACKSON, MISSISSIPPI 39212 COOK'S INSTITUTE I OF ELECTRONICS ENGINEERING E CIRCLE 58 ON FREE INFORMATION CARD 39 Spectrum r DAN DOBERSTEIN AND JOHN CARDONE C/5 m -v -t m £ m 3) 40 LAST MONTH WE DISCUSSED THE theory behind our PC -based 810- MHz spectrum analyzer. This month, we'll show you how to build it and discuss the software used to operate the instrument. Before we get into the con- struction, let's start off with a de- scription of the setup and operating software. All executa- ble files we mention here can be downloaded from the Radio- Electronics BBS (516-293-2283, 1200/2400. 8N1. file SPEC- AN.ZIP). Even before you build the analyzer, we would recom- mend that you download and run the software, (It will run even without the board installed.) Even though you won't get any meaningful data, it will help you to understand exactly how the software operates. Software and operation Before you can use the spec- trum analyzer, some software set- tings must be initialized so that the host computer will know at what address the analyzer re- sides, which printer port will be used, and the type of printer that will be used. The initialization is performed with SETUPEXE, which is a stand alone program that must be executed outside of the main program menu. The de- tails of using SETUP are covered in the README.DOC file. SETUP stores your system configuration and needs to be re-executed only if something changes. The two main programs are 810EGA.EXE and 810CGA.EXE. One is used for EGA systems, the other for CGA. Both programs operate the same way. The EGA version supports VGA/EGA monitors and has color ca- pabilities if your monitor sup- ports color. The CGA version has reduced graphics resolution and the sweep display will be mono- chrome. All the photos presented here are from the EGA version. The CGA version was included primarily to support low-end lap- top computers using the parallel- printer interface. When the software is executed, a copyright message will be dis- played while it is loading the cal- ibration files. After a few mo- ments the sweep display will come up. Figure 11 shows a typ- ical sweep display. The display is continually updated as the local oscillators's (LO's) are swept and new data is gathered. The box on the left side of the screen con- tains the list of function keys that are currently active. All user interactions from the sweep dis- play are initiated by function keys, arrow keys, or the ESC key. Function key Fl is always used to bring up the Instrument Setup menu. The user can change all the settings of the spectrum ana- lyzer from the menu. That will be covered in more detail later. Function key F10 activates the marker function. When the marker is on, the sweep is inter- rupted until a return to sweep mode is commanded (ESC key). Once the Marker is up, the user can do a peak search, or by using function key F7 toggle the delta marker on and off. The marker is moved using the arrow keys with the power and frequency (or delta power and delta frequency) dis- played in the lower left corner of the screen. Another feature of the marker is to tune the spectrum analyzer as you move it, enabling the marker to act as a station in- dicator for the FM demodulator. FIG. 11— THIS IS WHAT YOU might see on a typical sweep display. Using an external speaker and an antenna on the input you can "scan" the bandwidth of the ana- lyzer, listening for different FM broadcasts. Function key F8 activates a screen dump. Your printer must be selected using SETUP for this to work. A large number of printers are supported, ranging from Laserjets to low-end dot ma- trix types. When you return to ac- tive sweeping the marker turns off and the functions associated with it (FM tuning, screen dump, and so on) are not accessible to you. When you're in the sweep mode, you can save and recall all the settings of the analyzer using the function keys preceded by the ALT key for saving states, and the CNTRL key for recalling states. Ten states are available: one for each ALT/CNTRL function key pair. The states are numbered through 9 and are stored on the disk as STATEx.DAT STATEO is special because it is used as the wake up state of the machine. You can modify the wake up state of the analyzer by just saving a new STATEO using the ALT Fl keys. Instrument setup menu By using the up/down arrow keys of the setup menu you can move to the item you wish to change or execute by hitting re- turn. Start frequency, center fre- quency, and span determine the portion of the spectrum ana- lyzer's bandwidth you wish to ex- amine. Center and start frequen- cies cannot be independently chosen. In other words, you can only specify start and span or center and span frequencies. That's due to the fixed-span table approach used in the analyzer. The fixed spans are: 800, 600, 500, 400, 300, 200. 100, 50, 25, 12.5, 10,5, 2.5, 1.25, and 0.625 MHz. When the span is less than 12.5 MHz, the resolution band- width (RBW) is automatically switched from 280 kHz to 10 kHz. No direct user control is provided for the RBW setting. THE SOLDER SIDE of the foil pattern is shown here. THIS IS THE COMPONENT side of the foil pattern. 41 FIG. 12— PARTS PLACEMENT DIAGRAM. Note the location of the four coax runs. Make sure you install all chip capacitors first because of their small size. to o z o cr H O LU _l LU O o < rr All resistors are Vb-watt, 5%, unless otherwise noted. R1, R33— 3300 ohms R2, R31, R32, R43— 5600 ohms R3-R12, R37, R38, R46, R47, R49. R50, R66— 22,000 ohms R13, R22, R23, R27, R39, R40, R48, R53, R54, R57. R61— 470 ohms R14, R56. R60— 1000 ohms R15, R28-R30— not used R16, R17, R24— 18 ohms R18, R45, R59, R62—68 ohms R19— 180 ohms, 'A-watt R20, R52— 1800 ohms R21— 47,000 ohms R25— 240 ohms R26— 180 ohms R34, R35, R51, R55, R58— 56,000 ohms R36. R41, R42— 100.000 ohms R44, R64— 10,000 ohms R63— 390,000 ohms R65— 10,000 ohms x 7 SIP resistor Capacitors C1, C2, C22, C36, C40, C44, C45, C53, C56, C63, C64, C91— 1 jjlF, 50 volts, tantalum C3, C48, C60— 0.1 u.F polyester C4, C42, C49. C59— 47,000 pF, polyester C5, C6, C9-C18, C32, C46, C47, C61, C88-C90— 0.001 (iF, ceramic disc C7 T C62— 330 pF, ceramic disc C8, C68, C69— 100 pF, ceramic disc C19, C38, C66— 22pR ceramic disc C20, C26, C34, C37, C41— 10 pF, ceramic disc C21, C35, C67, C73— 1000 pF, chip C23, C71 , C74— 2.7 pF, ceramic disc C24, C25, C97— not used C27-C31, C33, C50, C70, C72, C75-C87, C92-C95— 0.01 (iF, ceramic disc C39 — 200 pF, ceramic disc C43, C51— 0.01 u.F, polyester C52, C54 — 1000 pF, polyester C55, C57, C99, C10O— 220 jxF, 35 volts, electrolytic C58— 220 (iF, 16 volts, electrolytic C65 — 5 pF, ceramic disc C96— 10 iaF, 16 volts, tantalum C98— 10 (j.F, 16 volts, tantalum Semiconductors IC1, IC2— Not used PARTS LIST IC3— MC34063, step-up voltage reg- ulator, Motorola IC4, IC5— 74LS244, three-state octal driver IC6— 74LS04, hex inverter IC7-AD558, 8-bit A/D converter, Analog Devices IC8— 74LS164, 8-bit par out shift register ICO, IC10— 74LS374. three-state octal driver IC11— 74LS32, quad or gate IC12— ADC0834, A/D converter, Na- tional Semiconductor IC13, iC16— NE615, receiver, Signetics IC14, IC15, IC23— MC44802, PLL, Motorola IC17— OE-1 75-14, tuner, Zenith IC18, IC19—74LS138, decoder IC20— 74LS688, address decoder IC21— 74LS245, bus transfer IC22— LM386, audio amp, National Semiconductor IC24 — NE602, oscillator/mixer, Signetics Q1-Q4, Q7— 2N3906, PNP transistor Q5, G8— MRF9G1, double emitter NPN transistor, Motorola Q6— 2N3904, NPN transistor D1, D4--MV209 or MV2105, varactor diode, Motorola D2— IN5229B, 4.3 volts, Zener D3— 1N4003, diode LED1 — Any red light emitting diode Other components L1— T10307, 0.15 mH, 7-mm can type, Toko L2— T10407, 1.0 mH, 7-mm can type Toko L3— 421F224, 5.8 to 3.7 mH, 7-mm can type, Mouser L4— 220 mH coil, Mouser L5— 3 turns of #30 AWG wire on #23 drill, LS = 0.138" L6— 5 turns of #30 AWG wire on #42 drill, LS = 0.2" L7— 3 turns of #30 AWG wire on #42 drill, LS = 0.138" T1— 421F128, 10-mm can type, Mouser T2— 42IF102, 10-mm can type, Mouser FL1, FL2, FL5—SKM1, 10.7-MHz ce- ramic fitter, Toko or Murata Erie FL3, FL4— CFM2-455E, 455-kHz ce- ramic filter, Toko XTAL1— 34.3000-MHz standard crystal XTAL2— XTAL107, 4.00-MHZ TTL oscillator 31 — 7-position DIP switch Connectors J1, J2, J4 — Female F-type bulkhead connector J3— RCA audio jack, PC board mounted (90°) J5, Jf3 — F-type connectors are part of tuning assemble (IC17) J7— 3-pin type, Molex, 0.156" O.C, power connector P2— 36-pin DIP header Two RCA male connectors for coax to tuner connection Miscellaneous • Bottom shield— 3-7/8" x 3-7/8" single-sided PC board with glass epoxy, copper side facing away from board. Four 1 /2-long screws, four 4-40 nuts and bolts, four lock washers and insulating washers. • Lowband shield— 2-1/4" x 2-1/2" sheet metal. • Rear panel with mounting screws. • 3 inches of 0.047 rniniture coax. • 16 inches of RG174 coax. Note: The following items are available from DKD Instruments, 1406 Parkhurst, Simi Valley, CA 93065; (805) 581-5771: A com- plete kit including executable and data files on a 5-1/4 inch disk with manual, S255.00; Cen- tronics interlace cable, $13.00; power cable, $4.00; an as- sembled, tested, and calibrated unit, $500.00. Send check or US postal money order. Allow 3 to 5 weeks lor delivery. California residents add 6% sales tax. 42 The reference level and at- tenuation settings determine the power level of the top line of the sweep grid. That is a user-entered number that can take on any floating-point value. The user has a choice of three settings for internal attenuation: 0, 10, and 20 dB. The attenuation is imple- mented by reducing the gain, not by the use of attenuation pads. That's a subtle yet significant dif- ference from high-end analyzers that use switched attenuators for gain reduction. User attenuation is located in the input path, which is convenient for automat- ically calculating in the effects of inline attenuations. Since that's a floating point entry, negative at- tenuations (or gains) can also be entered in the signal path. There are three choices for the vertical power scale units using the dB/ div entry: 2, 5. and 10 dB. Refer- ence level, attenuation, and dB/ div affect the placement of the power data on the sweep grid. It's best to experiment with different settings to get a feel for how they interact. Sweep rate The sweep rate determines how fast the display is updated and how long it takes to go through one sweep. It is directly affected by the CPU clock speed. For a given sweep rate, a faster PC will finish the sweep in less time than a slower PC. Sweep speed increases with higher values of sweep rate. The sweep rate and power accuracy are interrelated: longer sweep times usually result in more accurate power measure- ments. That has to do with the video bandwidth and PLL set- tling time. A fixed number of sweep rates are provided in the analyzer: 1, 3, 5, 10, 15. 20. and 30. A more complete discussion of the sweep rate and power ac- curacy relationship is given in the README.DOC file. Band select The band select menu item al- lows the user to select which in- put is going to be used: highband or lowband. The user must select the band of operation and con- nect to the appropriate input be- cause autoswitching is not pro- vided. The highband input should not be terminated when using the lowband input. That 10.7MHz TO 455kHz COAXIAL RUN SOLDER SHIELD OF COAX TO GROUND PLANE ^C26 FIG. 13— THE 10.7 MHz TO 455 kHz COAXIAL RUN reduces spurious pickup from the 455- kHz IF. would result in erroneous power measurements. The exit to sweep menu item returns the user to the sweep dis- play. Hitting the ESC key while on the menu bar docs the same thing. Exit to Dos returns control of PC to DOS. Calibration Three power related calibration files are used by the spectrum analyzer: one for the automatic gain control (AGC), one for the received-signal strength indica- tor (RSSI), and a user-generated error table. The AGC calibration tables correct any variations in gain using the DAC input to the AGC pin of the tuner. Most of the variations are in the tuner. One table for each value of internal attenuation is provided. A set of six data files are also used for the lowband and highband modes: namely the AGC*. DAT files. The RSSICAL*.DAT calibration files are used to "linearize" and map the RSSI voltages to an absolute power level. Two RSSI files are used; one for each RBW. Two user- gene rated files, POWERRH.DAT and POWERRL.DAT, can be used by kit builders to improve the accuracy of their power readings if they can get their hands on the equipment needed. The details of using the program USERCAL.EXE are covered in README.DOC. That error table is optional, and for factory cali- brated units it is zeroed out. If you build a kit, you'll have to live with the generic calibration files which, as mentioned above, result in degraded power ac- CHIP CAPACITOR DETAIL HOLD CHIP CAP WITH TOOTHPICK SOLDER PC BOARD CONDUCTOR FIG.14— USE THIS DIAGRAM asaguideto installing the chip capacitors. curacy. Most of the power errors come from variations in the gain of individual tuner modules, which are approximately ± 2 to 3 dB over the entire bandwidth. The RSSI data tends to change very little. Because of that, the largest errors will be at the band- switching points. The averaged generic calibration files are pro- vided with the kit, and are posted on the Radio-Electronics bul- letin board. Construction The entire circuit of the spec- trum analyzer is mounted on one double-sided PC board. We have provided foil patterns of the com- ponent side and the solder side of the PC board if you wish to make it yourself. Before mounting any components, you should visually inspect the board for shorts and solder bridges, especially around the pads that are surrounded by the ground plane. That can be done by putting a bright light be- hind the board, which really m H m DO ID 43 00 g z o Be h- u LJ Q 5 < RF INPUT TO TUNER COAX TIN SHIELD SOLDER TO RCA BRAID SHIELD FOR SOLDERING TO GROUND PLANE R Gl 74 WITH OUTER INSULATION REMOVED J6 RCA MALE JACK TORF INPUT OF TUNER TUNER L0T0PLL1 COAX J5 SOLDER TO RCA HCA ^ALE SH , ELD JAOK TO IC15L0 INPUT (C6.PLL1) TUNER LOOUT ^m ATTACH TO GROUND PLANE FIG. 15— TWO RG-174 COAX RUNS ARE SHOWN for the RF input to tuner (a) and the tuner LO to the PLL1 (o). TO T" BULKHEAD CONNECTOR HIGHBAND INPUT LUWBAND INJECTION COAX KEEP EXPOSED CENTER CONDUCTOR TO A MINIMUM LENGTH C66 22pF LOWBAND INJECTION OF 145MHZ IF SOLDER TINNED SHIELDS TO GROUND PLANE FIG. 16— THE RF FEED FOR the lowband injection coax. Make sure your center conductor is as short as possible. makes the pads standout. After careful visual inspection, check the +5-, +12-, and +33.3-volt power buses for shorts to ground. Figure 12 shows the compo- nent placement, as well as the lo- cations for all coax runs. Before mounting any components, a short coax run must be installed on the top side of the board. A small piece of semirigid coax is used to connect the 10.7-MHz IF from FL5 to the input from the 455-kHz IF mixer (IC13, pin 1). The coax reduces the spurious pickup for the 455-kHz IF. Cut, strip, and bend the coax as shown in Fig. 13. Using an ohm- meter, check to make sure the in- ner conductor is not shorted to ground. RG174 type coax, with the external insulation removed, can be used but it's a tight fit. You're now ready to start sol- dering in the components. Install chip capacitors C21, C35. C67. C72. and C73 first, using Fig. 14 as a guide. Because of their small size they can be very difficult to install with the board fully stuff- ed. Solder in all remaining capac- itors. Check them off on the parts list as you install them, then re- check the power buses with an ohm meter. You should read infi- nite resistance, as before. If you read a short or very low resis- tance, look for solder bridges. Now solder in the resistors ac- cording to the component layout. Again, check the power buses for shorts using the ohmmeter. In- stall the inductors and coils next. Ifyoubuyakit, L5, L6, and L7 are already made. Install all filters and crystals. Their leads can go in either direction. Lay XTAL1 down flat and solder its case to ground. The case of XTAL2 should also be tied to ground using a small piece of wire. Sol- der in the diodes, being careful to observe the correct polarity. Do the same for transistors QI-Q8. Q5 and Q8 are surface-mount types from Motorola; "M" marked on the top indicates the collector. Using the ohmmeter again, check for shorts on the power buses. When installing the IC's, use sockets for all the chips except the NE615's, MC44802s, and the NE602. Those chips need a close connection to the ground plane to ensure proper operation. Check for shorts again. After you install IC3 (the MC34063 step-up voltage regulator), make sure you have 33.3 volts DC between R62 and ground. That is where the 33.3-volt power line comes from. If you really want to be thorough, use an ohmmeter to check every IC pin for shorts to ground and verify that the pins that should be grounded are grounded. Now install the mechanical parts: the RCA jack, 3 -pin Molex connector, 36-pin dual header (for the paral- lel interface), DIP switch SI, and R64. Tuner installation Before the tuner can be in- stalled, two RG-174 coax runs to the RF input and the LO output must be connected, as shown in Figs. 15-a and -b. If you don't get the lowband option, the RF input is just a direct feed using RG59 cable to a female/female F-type connector on the rear panel plate. After the cables are made, con- nect the LO cable to the board and solder the coax shield to the ground plane. Now make the RF feed. (If you have the lowband op- tion. Fig. 16 shows you how to connect the coaxial cable to the board.) Using the outer shield of the 44 lowband coax as a gauge, put the tuner on the board, top side up, by tacking the corners down with solder. Don't solder the lowband shield on yet, that goes on after tuning L6. Two holes are pro- vided for using tie wraps to hold down the tuner if you desire. Cut small pieces of wire to connect tuner pins 1—8 on the bottom edge to the appropriate holes on the board. Make sure the if out jumper is as short as possible. Now connect the two RCA jacks for the lo out and the rf in coax runs. Terminal panel and shield Before you mount the terminal panel to the board, connect the highband coax run as shown in Fig. 17. Connect the coax to the board first, then connect the low- band and comb F connectors to the terminal panel. Now connect the highband F connector to the terminal panel and secure the panel to the board using two 4-40 screws and nuts. Solder jumpers from the plated holes in the printed-circuit board to the cen- ter conductor lowband and comb F connectors. Figure 18 shows the mounting details of the bottom shield, which is made of a single-sided PC board and is mounted, with the copper side facing away from the main board, using four 4-40 bolts. This shield should be in place before you perform any final tuning as it effects signal levels. Coil pretune We're almost ready to power the unit up, but first we need to pre- tune the coils. Most of coil adjust- ments are noncritical. Use the following initial settings just to get you started: • LI — Slug is Wi turns from the bottom (fine adjust later). • L2 — Slug is l'/2 turns from the top ( ± 1 turn). • L3 — Slug is all the way to the bottom. • L5 — Close wound. • L6 — Close wound. • L7 — Close wound. • Tl — Slug is IV2 turns from the top, • T2-^Slug is I'/a turns from the top. The spectrum analyzer should work with those settings. All ad- justments from here on for fine tuning. HIGHBAND COAX TO REAR PANEL TIN SHIELD AND HERE SOLDER TO 'TCONNECTOR J1 HIGHBAND INPUT "PJACK RG174 OUTER INSULATION REMOVED TIN SHIELD AND SOLDER TO GROUND PLANE NUT REAR PANEL SOLDER TO CENTER CONDUCTOR OF BULKHEAD JACK FIG. 17— THE HIGHBAND COAX RUN is shown here. This coax connection must be made before the terminal panel is installed on the PC board. BOTTOM SHIELD 4-40 BOLTS (4) Vi" LONG TUNER COPPER SIDE SINGLE SIDED (3 7 /«"x3 7 /s") GLASS-EPOXY BOARD COPPER SIDE DOWN INSULATING 4-40 NUT--" \ WASHER 4-40 NUT FIG. 18— THE BOTTOM SHIELD ASSEMBLY is shown here. Make sure the copper side of the shield is installed away from the PC board. First power up Put the card in the computer or, for external use, connect it to a parallel port and external power supply. Connect the comb output to the highband input and turn it on. Check the +5-, +12-, and + 33-volt levels to make sure they are correct. Run either 810EGA or 810CGA program, depending on your video adapter. The sup- plied wake-up state is a span of 400 MHz with a start frequency of 100 MHz. Assuming every- thing goes well, you should see a series of lines 4 MHz apart slowly rolling off in amplitude. If you don't, go to the "Troubleshoot- ing" section. Tuning the unit The spectrum analyzer can be used to fine tune LI, L6, Tl. and T2; L2. L3. L5, and L7 should need no further adjustment. Ad- justing the coils is easier with the card outside of the PC case, for instance if you use the parallel 0) m | m c r- to tc 45 LOWBAND SHIELD -2Vz" 10 O Z o BE P o in _i iij o Q < en BEND OVER AT DOTTED LINES INTO V" SHAPE FIG. 19— THE LOWBAND SHIELD is sol- dered on the top side of the PC board. CORRECTIONS There may have been some con- fusion where the DAC output from IC7 {Fig. 10) goes to from our Part I article. Just to clarify those con- nections, we have redrawn the correct DAC outputs in Fig. 20. Two other corrections are noted below. • The power-supply line to Pin 2 of IC15, IC23, and IC14 is 33.3 volts DC. • Two signal labels, LO JN and v tune' should be reversed in IC23 or the signal-processing block di- agram (Fig. 6). + 12V FIG. 20— THE DAC OUTPUT from IC7 goes to IC17 and IC12 as shown here. interface. Allow about 5 minutes for warm up and then tune the coils in the following sequence. The maximum span available from the lowband is affected by L6. It is tuned by spreading, or closing, its turns. Connect the comb out to the lowband input and set the spectrum analyzer as follows: • Bandselect — lowband • Span— 100 MHz • Start freq— 5 MHz • Inter atten— 10 dB • Ref level 40 dBm The sweep display should show lines every 4 MHz. If the upper end lines are missing, open up L6 a little and the upper lines should start appearing. You should be able to see the line at 104 MHz when L6 is adjusted properly. Once L6 is adjusted and you're confident that the lowband cir- cuit is working properly, install the shield over the circuit. Figure 19 shows the details of that shield. Set LI by observing the power level of the noise floor. Terminate the highband input in 50 to 75 ohms and set the band select to highband. Use the following set- tings to make a measurement: • Span— 12.5 MHz • Center frequency — 120 MHz • Sweep rate — 3 • Inter, atten— 10 dB • Ref level— -40 dBm The sweep display should show almost a flat line. Turn the slug of LI until the noise floor reads -100 dBm. An alternative and more accurate method requires a crystal source of known power level. For best results, the fre- quency of the source should be between 100 to 500 MHz. Set the spectrum analyzer to display your line using the 12.5-MHz span and a sweep rate of 1. Now adjust LI so that the power level of your line is correct. Tl is tuned by using the spec- trum analyzer as an FM radio. The setup settings are: • Span— 25 MHz • Start freq— 85 MHz • Band select — highband • Volume potentiometer (R64) — centered Connect an antenna up to the highband input. You may have to use an outside antenna. You can make a simple antenna by at- taching a 2- to 3-foot piece of wire to the center conductor of the in- put. Connect a speaker to the au- dio out RCA jack. Now let the analyzer make a few sweeps. You should be able to hear FM broad- casts as the analyzer sweeps by them. Now activate the marker and find a strong station. Put the marker at the peak of the signal, even if the audio drops out. Ad- just Tl now for the best sound. T2 can be adjusted the same way, but you'll have to pick off the au- dio and amplify it as it is not con- nected to an amplifier. You will also need a narrowband FM broadcast for proper adjustment. With a little hunting you should be able to find one. (Try your local National Weather Service broad- cast station in the 162.4-162.6 MHz band.) The adjustments of Tl and T2 only effect the FM de- modulation and do not effect the accuracy of the instrument. Troubleshooting Typical symptoms indicating a problem are a flat or "pegged" sweep display and no response to inputs. Two programs are avail- able to help in the troubleshoot- ing process; BLINK.EXE and ADCDAC.EXE. BLINK is used to give a simple visual indication that the host PC has some com- munication with the card. With the card plugged into the PC or parallel cable, run BLINK, The LED on the card should blink at approximately 1-second inter- vals. If no blinking at all occurs, you have a communication prob- lem with the PC. Double check the interface settings using SET- UP; if those are wrong the card won't respond. If wiggling cables, checking power-supply voltages, and every permutation of inter- face selections does not result in a successful BLINK, you most likely have a hardware problem. ADCDAC.EXE is a more exten- sive test in that both reading and writing to the card are involved. There is little chance that this test will be successful if BLINK fails. ADCDAC sends a voltage level to the DAC, then reads that voltage using the ADC. If the read voltages are within the toler- ances, the test is declared a suc- cess. ADCDAC returns a pass/fail verdict upon completion. If you fail, it could be an interface prob- lem or a problem with the ADC or DAC. Passing does not guarantee that all systems are go, just that the interface and ADC/DAC seem to be working. If you still can't find the prob- lem, see README.DOC for more things to try, or call DKD Instru- ments at (805) 581-5771. They'll be happy to help you. R-E 46 DAVID T. MIGA, CET t*« _ ES,GW »*C Wt(Jrs e <"0d e __. c _ 6DS-76 „.. J * • • •* cap ^ Nef» Pch IW VOLTS - HL,^ HV c BUILD THE MICROANALYZER Repair microwave ovens the easy way with the Microanalyzer. DID YOU KNOW THAT MICROWAVE ovens were invented more than a quarter century ago using tech- nology more than half a century old? Even so. many electronic technicians are reluctant to ser- vice them because they do not understand them. That's a shame, considering the fact that there are millions of them in use. True, there is enough power in even the smallest microwave oven's power supply to kill a per- son, yet most technicians repair television receivers with many times more voltage without giv- ing it another thought. The point is that a technician with the proper knowledge, who follows safe, intelligent procedures will never have a bad experience, and can make lots of money. This arti- cle explains how microwave ovens work, and shows you how to check all of the critical parts using the Microanalyzer project that we'll show you how to build. How they work A microwave oven is similar to been purposely tuned to be un- stable, and therefore to oscillate. The oscillator/amplifier tube is called a magnetron, and its sche- matic is similar to an ordinary tube rectifier (see Fig, 1). How- ever, instead of the electrons hav- ing free space to boil off of the filament/cathode to be grabbed by the plate, the electrons are purposely frustrated by placing a powerful circular magnet around the cathode, causing the elec- trons to rotate around the cath- ode on their way to the plate. There are cavities in this section of a critical diameter that will cause the oscillations to be of a certain frequency, usually 2450 MHz, Because the plate of the tube does not operate at a high voltage, but instead is at ground potential, the cathode, therefore, is powered by a very high nega- tive voltage, usually between three and four thousand volts. The filament of the tube is di- rectly heated, so it must be capa- ble of handling the high negative voltage as well as passing a 3 -volt AC filament current of about 10 amps. In most microwave ovens a single power transformer has both high -voltage and low- volt- age secondaries. The magnetron tube has a wire in the plate cavity that intercepts the swirling electrons and passes the energy to the top of the tube where the energy is transmitted by a small antenna timed to the proper wavelength. The energy therefore transmits horizontally, similar to the ripples in a pond caused by a dropped pebble. The microwaves are routed by a square metal tube, or duct, called a waveguide, whose cross dimen- sions are tuned to the same wave- length as the magnetron. The waveguide directs the micro- waves to the inside of the oven through a plastic or mica panel called a waveguide cover. The cover keeps food panicles, grease, and steam from entering the waveguide, yet passes the magnetic energy. Most microwave ovens have a stirrer, which can be motor acti- vated, or in many ovens may be blown propeller style by the air »nc CO m u S 03 m ID 47 forced through the cooling fins of the magnetron. The stirrer is in the top of the oven, and it reflects the microwaves all around the oven cavity. All microwave ovens have safe- ty features to prevent unsafe mi- crowave emissions. A series of micro-switches operate in a cer- tain sequence, and are in series with one or more thermal switch- es, so as to assure that the power supply will operate only when all of the switches are in their cor- rect positions. There's even a switch designed to short out the AC line, blowing the fuse, if any of the switches malfunction (see Fig. 2). In operation, a mechanical timer or an electronic control unit will cause a relay or triac to pass 120-volts AC to the primary of the power transformer. The transformer has a 3-voit second- ary for heating the magnetrons filament, and a 1500- to 2500- volt secondary for the high-volt- age power supply. To keep the windings count low, a voltage- doubler circuit is used (see Fig. 3). During one half of the 60-cycle current, the transformer charges a high-voltage capacitor to ground through a high- voltage diode, cathode to ground. When the polarity reverses, the capaci- tor is free to discharge through the high-voltage winding. Since the voltages are in series, the voltage is doubled, although the current is reduced to what the capacitor can supply during its discharge. Therefore, the size of the capacitor controls the wat- tage, and the magnetron actually transmits energy in 60-Hz pulses. Note that the capacitor may remain charged for hours after using the oven, so it must be properly discharged before any components in the oven are checked. When a microwave oven is op- erated, the magnetron usually takes about 3 seconds to fire up, because the filament must come up to temperature. If one listens, the firing up is audible: the mag- netron emits a 1-second buzz im- o mediately after the filament heats g up. In most ovens with several oc power settings, the actual power o delivered to the magnetron does jjj not vary, but instead is cycled on o and off by the controlling circuit- Q ry. The fan and light stay on, but en the primary of the power trans- en FIG. 1— A MICROWAVE OVEN'S oscillator/amplifier tube is called a magnetron. The electrons are purposely frustrated by placing a powerful circular magnet around the cathode, causing the electrons to rotate around the cathode on their way to the plate. There are cavities in this section ot a critical diameter that will cause the oscillations to be of a certain frequency, usually 2450 MHz. former is energized or de-ener- gized by a relay or triac, as shown in Fig. 4. More sophisticated ovens may use a temperature probe, or even a heated tin-oxide gas-vapor sen- sor to determine when the food is cooked. The thermistor's resis- tance in the probe, or the voltage output of the gas sensor, is routed to a microprocessor, which has been programmed with the proper values to turn off power when the food is fully cooked, or "smells" done. The Microanalyzer The Microanalyzer is actually several pieces of test equipment rolled into one easy-to-carry cab- inet. First, a 3 '/a digit DVM is in- corporated to measure up to 500- volts AC or DC, with a high-volt- age input that allows up to 5000- volts AC or DC. Second, a high- voltage supply is wired to a cir- cuit that allows the testing in-cir- cuit of the high- voltage diode and capacitor, with test voltages as high as 700 volts peak-to-peak. The results are plainly displayed by four neon indicators. Third, a semiconductor checker allows the testing of devices such as tri- acs, silicon controlled rectifiers, bipolar transistors, diodes, and MOSFETs. Figure 5 is the schematic of the Microanalyzer. Power trans- former Tl has a low-voltage sec- 48 120 VAC DOOR INTERLOCK SWITCH #1 /fTX MAGNETRON THERMAL SWITCH DOOR LATCH SWITCH I TO PRIMARY OF POWER TRANSFORMER FIG. 2— ALL MICROWAVE OVENS have safety features to prevent harmful emis- sions. A series of micro-switches and thermal switches assure that the power supply will operate only when all of the switches are in their correct positions. ondary that provides power to the DVM chip, IC2, via diode bridge BR1 and regulator IC1. as well as AC power to the semiconductor tester. The high-voltage second- ary provides 250-volts AC for the high-voltage diode and capacitor tester. A small sample voltage is taken from the secondary's cen- ter tap via R30, D12. and D9 for the negative voltage required by IC2. Selection between the DVM, the capacitor tester, and the di- ode tester is done by three-pole, three-position switch S2, In the "capacitor- test" and "diode- test" positions, one pole of S2 con- nects the internal high-voltage source to banana jack J2 ; a sec- ond pole turns off the DVM dis- play via D8, R25. and Q3; the third pole selects either high- voltage AC for testing diodes, or DC for testing capacitors. If the selector is placed in the "diode- test" position, a 250-volt RMS po- tential is placed through current- limiter Rl to the diode under test between Jl and J2. Across Rl is neon-indicator NE3. which will light only if the AC current flow is in the wrong direction; if the diode is shorted, for example. Diode D5 will keep NE3 off if the diode under test is good. The diode-OKneon indica- tor (NE1 ) will illuminate only with DC, since AC will be bypassed across NE1 by CI and C2. The FIG. 3— TO KEEP THE POWER TRANSFORMER'S windings count low, a voltage-doubler circuit is used to generate high voltages. MAGfJtTRON INTERLOCK SWITCHFS 1 20 VAC LOW-VOLTAGE POWER SUPPLY HIGH VOLTAGE POWER SUPPLY ^ CONTROL FIG. 4— IN OVENS WITH SEVERAL POWER SETTINGS, the magnetron is cycled on and off by the controlling circuitry. The fan and light stay on, but the primary of the power transformer is energized or de-energized by a relay or triac. diode-open neon indicator (NE2) cannot light if the diode under test is good, since the diode will keep the positive voltage across R5, D6, and NE2 under 8 volts, which is the forward-bias poten- tial of a good high- voltage diode. Diode D6 will keep NE2 off dur- ing negative flow; however, if the diode under test is open, there is sufficient positive voltage to light NE2. Flipping S2 to the "cap-test" position switches Dl in line which causes a pulsating nega- tive DC voltage to appear across Rl. With an open circuit, NE1 and NE3 will be off because there is insufficient voltage across Rl to illuminate either one. Indica- tor NE2 will be off because only a positive voltage can light it, and NE4 will be off because the 250- volt DC signal is not high enough to break down the reverse junc- tions of diodes D3 and D4 in se- ries with NE4 and R2. If the capacitor under test is 0. 1 p-For higher, the negative cur- rent flow will charge it through Dl; however, when the current flow reverts to positive, Dl blocks the flow, which now is the com- bined voltage of Tl's secondary in series with the charged capaci- tor. The combined voltage is now enough to break down the re- versed junctions of D3 and D4, protected by current-lirniter R2, and NE4 glows . A val ue below . 1 p\F will create a voltage lower than NE4 usually requires to conduct, so C14 is placed across NE4 to charge up to NE4's ionization point. Because of that, any ca- pacitor that is below the normal value found in most microwave ovens will cause the NE4 to flash, due to the relaxation oscillator circuit. Capacitor values of 0.5 H-F or higher will illuminate NE4 continuously, while smaller and smaller values will cause NE4 to flash slower and slower. 49 50 FIG. 5 — POWER TRANSFORMER T1 has a low-voltage secondary thai provides power for the Microanalyzer's circuitry. The high- voltage secondary provides 250- volts AC for the high-voltage diode and capacitor tester. TO S2-b COMMON (FIG.7) FIG. 6— ALL COMPONENTS ON THE MAIN BOARD are mounted on the component side except (or R32 and R33 which must be tack-soldered to the solder side of the board. One quirk of this circuit is that if the capacitor under test is shorted, not only will short-in- dicator NE3 glow, but so will NE1, the diode-OK indicator. Since a capacitor is under test here, the user can simply ignore the diode- OK lamp. If that is bothersome to the user, a 4-pole switch may be used for S2, with the fourth pole used to switch in NE1 in the "di- ode-test" position only The voltmeter circuit uses the popular 7107 DVM chip (IC2). The AC/DC switch (S3) switches D7 in or out so that IC2 always sees either positive or negative voltage, but never AC. Because the single diode is a half-wave rectifier, normally the reading will be only a small portion of the true RMS voltage; therefore, a second pole of S3 switches from R23 to a trimmer, R34, so that the meter can be adjusted to read the correct RMS voltage in the "AC" position. Because IC2 uses an on-board oscillator for the dual-slope integrating analog- to- digital converter, trimmer-capac- itor C13 has been added across C8 so that the sampling frequen- cy can be varied. If the trimmer capacitor is left out, any AC volt- age readings may be unstable; therefore, the chip's sampling frequency can be adjusted to an exact multiple of the 60-Hz AC voltage to be measured. Trimmer R35 is the basic refer- ence-voltage adjustment used to calibrate the DVM on the lower scale DC measurement. The val- ues of R7 and R23 or R34 will correctly divide the input voltage up to 500 volts AC or DC down to 2 volts for the DVM chip (IC2). but if anything up to 5000 volts must be measured, the voltage is passed through banana-jack J2 which uses R8— R15 for an addi- tional 43 megohms to reduce the voltage to a compatible level. The circuit containing Ql and Q2 constantly measures the volt- age at J2. If any AC or DC voltage appears at J2, one or both tran- sistors are biased to turn on the decimal-point LED in the display. Stereo phono-jack J4 is used for testing semiconductors. A matching phono plug, PL1, with a black lead on the outer conduc- tor, a red lead on the middle con- ductor, and a yellow lead on the tip conductor, plugs into J4 and provides test clips to attach to components. The 5-volt AC source from Tl is passed through LED1 and LED2 through cur- rent-limiter R16. Both LED's will remain off when the test leads at J4 remain unconnected, but both will illuminate when the red and black leads are shorted. To test a semiconductor, connect the red lead to the collector of a transistor, the anode of an SCR, MT2 of a Iriac, or the drain of a MOSFET; connect the black lead to a transistor emitter, SCR cath- ode, triac MT1. or MOSFET source; and connect the yellow lead to a transistor base or gate of any other part. Pushing test but- ton S4 will forward-bias the de- vice and, depending on whether either, both, or neither LED lights, a semiconductor device can be tested for proper con- ductance. More details on the testing will be given later. en m IX m 33 51 u z o IX F o UJ 6 D < DIODE FIG. 7— MOUNT THE PARTS ON THE DISPLAY BOARD as shown here. Note that R6 and C14 are soldered to the back of th,e board. Construction The Microanalyzer consists of two single-sided PC boards: a main board containing the power supply and the DVM chip with auto decimal -point circuit- ry, and a display board con- taining the indicators, displays, switches, and test jacks. The dis- play board is joined to the front of the main board by soldering in- terconnecting foils at their edges. We've provided the foi! patterns in case you'd like to make your own boards. Alternatively, the boards, as well as complete kits, are available from the source mentioned in the parts list. Almost all components, except the power transformer and switches SI and S5, are mounted on the PC boards. Follow the parts layouts for the main and display boards. Figs. 6 and 7, re- spectively. Solder all jumpers on both boards first, followed by the fuse, resistors, trimmers, diodes, capacitors, transistors, regulator [CI, and sockets for the 7-seg- ment displays and IC2, in that order; do not put IC2 in its socket just yet. Prepare switches S2-S4 by soldering 1-inch lengths of sol- id wire to the terminals to make them PC-mountable. Do not put too much solder on S2 or else it may not fit between the display board and front panel. Mount, but do not solder the neons, LED's, and prepared switches in the display board. In- sert the digital displays in their sockets. As indicated by the dashed lines in the parts-place- ment diagrams, tack-solder R32 and R33 to the back (the solder side) of the main board, and R6 and C 14 to the back of the display board. Hold the display board in position next to the main board using the slots and bosses in bothboards, and solder all of the foil connections, making sure that the boards are exactly per- pendicular. Check all connec- tions for solder bridges. Solder the power-transformer wires to the main board, and sol- der three 4-inch wires in the holes marked for both switches SI and S5. If you are using an illuminated switch for S5, install 6-inch wires in the holes marked LED3. Solder the power switch (SI) to its wires. Assuming you have purchased a ready-made front panel and case {see the parts list), you can mount all of the jacks and indica- tor lenses on the front panel just like the prototype, and slip four 5 /s-inch heat-shrink tubes over the neons. Otherwise you can make your own front panel in a similar fas ion. Remove all hard- ware from S2— S4, but leave one nut on S3. Mount the front panel and the PC-board assembly in the bottom shell of the cabinet. The neons, LED's. and switches can now be extended to reach the panel to be mounted. Adjust the nut on S3 to match the shaft length of S2, and install and tighten the remaining hardware for all three switches. Solder the components after they have been mounted. Also mount SI and S5 in the panel and wire them up; note that the other side of S5 is connected to the rear of the dis- play board on the center contact of S2 (S2-b common). Remove the assembly from the cabinet, turn it over, and wire up jacks Jl— J4 to the holes marked on the display board using the shortest possible lengths of very thin solid wire. Remember to wire the LED3 wires to the in- dicator inside S5 only if a 5-volt bulb or LED is installed: the in- dicator will light only when the 52 PARTS LIST All resistors are '-i-watt, 5%, un- less otherwise Indicated. R1— 10,000 ohms R2— 47,000 Ohms R3, R5— 22,000 ohms R4— 39,000 ohms R6, R17— 220 ohms R7, R11, R19-R22, R36— 10 megohms R8-R10, R12-R15, R18— 4,7 megohms R16— 150 ohms R23— 10,000 ohms R24 — 1 megohm R25— 2200 ohms R26— 25,000 ohms, metal, 1% R27— 5600 ohms R28— 100,000 ohms R29 — 470,000 ohms R30— 68,000 ohms R31 — 120 ohms (optional for illumi- nated S5, see text) R32, R33 — 180.000 ohms R34— 50.000 ohms, 10-turn trimmer R35— 1000 ohms, 10-turn trimmer Capacitors C1, C2— 0.47 ^F, 350 volts, electrolytic C3 — 47 h,F, 16 volts, electrolytic C4 — 1000 p.f, 25 volts, electrolytic C5— 220 jjlR 16 volts, electrolytic C6, C7— 0.47 |iF, 100 volts. Mylar C8— 100 pF, polystyrene C9— 0.1 n.F, 100 volts, Mylar C10— 0.01 |j.F, 100 volts, Mylar C1 1—0.047 (i.F, 100 volts, Myiar C12— 0.22 m-F, 100 volts, Mylar C13 — 30 pF, ceramic micro trimmer C14— 0,47 nR 200 volts, Mylar C15— 120 pF, 500 volts, silver mica Semiconductors IC1— 7805 5- volt regulator IC2— ICL7107CPL 3Vfcdigii DVM chip D1, D2, D5-D7, D12— 1N4007 diode D3, D4, D8— 1N4148 diode D9-D11— 1N4733 5-volt Zener diode BR1— ECG5304 400-PIV 1.5-amp bridge rectifier Q1, Q3— 2SA733PNP transistor Q2— 2SC945 NPN transistor LED1. LED2 — orange light-emitting diode LED3 — light-emitting diode or 5-vo!t lamp (optional for illuminated S5) DSP1-DSP4— MAN 4710A com- mon-anode 7-segment LED display Other components S1— SPST pushbutton switch S2— 3PDT CO. switch S3— DPDT switch S4— SPST pushbutton switch S5 — SPST pushbutton switch (illumi- nated optional) T1— 120 VAC primary, 250 VAC C.T 25 mA secondary, 6 VAC, 1 amp secondary J1 , J2 — red banana jack, '/s-inch J3 — black banana jack, '/2-inch J4 — stereo mini phono jack PL1 — stereo mini phono plug F1— 1A, 250V pigtail fuse, Littlefuse 318.500 NE1-NE4 — NE-2H neon indicators Miscellaneous: Amerex 570 black cabinet, hardware, AC line cord, 3.5mm lamp lenses, wire, solder, etc. Note: The following parts are avail- able from EDS, Inc., 275 Rock Is- land Road, N. Lauderdale, FL 33068: Set of drilled and screened main and display PC boards for $25; kit of all parts and boards for S199; complete kit including Amerex cabinet with screened and machined front panel for $249. Please in- clude $4 shipping for boards only, or $8 for kits. Florida resi- dents must include 6% sales tax. diode or capacitor functions are selected, while the digital display will illuminate only when the se- lector is in the "volt" position. Mount transformer Tl to the cen- ter floor of the cabinet using #8 bolts and nuts. Run the AC line- cord through the hole in the back of the cabinet and solder the leads to the main board. Install the line-cord strain relief: you may have to melt it to the inside of the cabinet for added strength. Finally, mount the assembly to the bottom shell of the cabinet and proceed with making of the test leads. Figure 8 shows the in- side of the completed unit. Because the unit will be used to measure potentials up to 5000 volts, it is important to use wire intended for use as test leads, such as the rubber-insulated va- riety. Solder fully insulated ba- nana plugs to one end of the wires, and fully insulated al- ligator clips to the other end. The semiconductor test wire is made from an ordinary piece of 4-con- ductor telephone wire, with only the red, black, and yellow wires used. Solder a 3,5-mm stereo phono plug (PL1) to one end. being sure that the pin-out matches the jack ( J4), and solder small IC clips or micro alligator clips to the remaining end. After you have checked for sol- der bridges, bad connections, and proper component polarities and values, you can apply power. Measure the voltage at the positive terminal of C5; it should be +5-volts DC measured to ground. The anode of D9 should measure — 5-volts DC, and the S5 pad on the main board should be 250-volts AC. If the voltages appear to be normal, turn off power and install IC2 in its sock- et. Turn on power and cycle S2 to be sure that the digital display and LED3 work properly. If every- thing looks good, plug in the high- voltage test leads and put S2 in the "diode test" position. Press S5 and verify that NE2 (open diode) illuminates. Short the test leads and press S5 again to see that NE3 (short) lights. Now. connect a high- voltage test diode with red at anode and black at cathode, and check that NE1 (diode OK) lights. Note that if the diode is connected backwards, all three diode- test lamps will il- luminate simultaneously. Check the capacitor- test func- tions with high-voltage capaci- tors rated between 0.01 and 1.0 jiF and verify the correct func- tions of NE3 and NE4. Re- member that voltages across the test leads can be as high as 700 volts p-p when S5 is pressed, so please be careful. Since the test voltages are fully isolated from the power line, and one hand is needed to push the test button, it would require a three-handed person to get a shock, but the warning is given anyway. Next check the semiconductor tester. Plug in the 3-conductor test cord and connect the ends to an NPN transistor using red for the collector, yellow for the base. and black for the emitter. With- out pressing S4, LED2 may be dark or slightly lit. That is nor- mal reverse leakage for an NPN transistor, and will be brighter when testing low-voltage, high- en frequency transistors. Pushing -v S4 will darken LED2 and brightly | illuminate LED1, showing trans- w conductance. Testing a PNP tran- 33 sistor should yield reversed g indicators. f£ S3 GO a z O a: — o LLl Q < Test and calibration To Lest and calibrate the volt- meter, you will need to construct a test jig using an actual micro- wave oven's power transformer. You will not have to remove the transformer, but just remember that during these tests that you will be exposing yourself to po- tentially lethal voltages. Use rub- ber gloves and have someone else nearby to supervise. Construct a string of five I-megohm, 'A-watt. 2% resistors from the trans- former's high-voltage output to ground, with a 1N4007 diode and 0.01-jxF/lkV ceramic capacitor connected as shown in Fig. 9. Disconnect the lead from the high-voltage output of the trans- former to the high-voltage capac- itor to keep the ovens magnetron from firing. Connect a DMM (set to its high- est DC voltage range) in parallel with the Microanalyzer's test leads, with red to the DC test point of the test jig, and black to ground. Be sure that both meters are set to DC and, after checking and covering all exposed connec- tions, plug in and turn on the microwave oven. Using your DMM as a reference, adjust R35 for the same reading. Turn off and unplug the oven, and switch to the AC test point. Set both meters to AC, then turn on the oven again. If the digital display seems to be unstable or hunts up and down, adjust C13 with an insulated alignment tool until the readings settle down. After that has been done, adjust R34 for the same reading as your DMM, Turn off and unplug the oven, then move the red banana plug to the high-voltage test jack J2, Turn on the oven again and verify that the decimal point il- luminates when voltage is pres- ent, and the reading of the display is shifted one digit to the left so that the display reads kilo- volts to the nearest 120 volts. If the accuracy is poor, you can re- place Rll (10 megohms) on the display board with different val- ues from zero to 10 megohms. This completes all testing and calibration. Use Since we have learned that mi- crowave ovens are simple devices with a high-voltage power supply, magnetron tube, and some type FIG. 8— THE INSIDE OF THE COMPLETED UNIT. The transformer and PC-board assembly are mounted in the bottom shell. i TO H.V. WINDING OF ~6 MICROWAVE POWER TRANSFORMER ALL RESISTORS ARE 1 MEG, 5%, Vi WATT CALIBRATION POINTS OAC DCO 1H4007 j_0.01nF "^ 1kVDC FIG. 9— CONSTRUCT A STRING of five 1- megohm, Kt-watt, 2% resistors from the transformer's high-voltage output to ground, with a 1N4007 diode and 0.1-(jLF,1kV ceramic capacitor connected as shown. of control circuit, troubleshoot- ing is usually straightforward unless the oven has an intermit- tent problem. If an oven is "dead," check and replace, if nec- essary, the fuse with the correct type; most ovens use a ceramic self-quenching type fuse. Put a cup of water in the oven and fire it up. If there is still no function, or if it lights but doesn't heat, un- plug the oven and discharge the capacitor by connecting a test clip to ground, touch one, then the other capacitor terminal to ground. Now using the clip, short across the terminals. Since this method discharges the capacitor through the transformer first, the discharge will be less violent. The first type of tests are "stat- ic" tests, meaning that the com- ponents are checked with the oven unpowered and unplugged. Turn on the Mieroanalyzer and switch to "capacitor test." Con- nect the black lead to the capaci- tor terminal connected to the high-voltage secondary, and the red lead to the capacitor terminal connected to the anode of the high-voltage diode. Depressing S5 should indicate a good capaci- tor, with no flashing of the in- dicator. If the indicator flashes, or the short indictor lights, dis- connect all wires to the capacitor and check it again. If the capacitor checks out, move the black test clip to ground, with the red lead re- maining connected to the anode. Switch to "diode test" and press S5. Remember that if the tesL leads are connected backwards. all three diode test lamps will light. When testing capacitors and diodes, keep S5 pushed in for a few seconds. All indicators should be steady, as flickering lamps may indicate an intermit- tent breakdown problem. If the diode and capacitor are good, check the magnetron fila- ment. Full both wires off of the 54 USE THIS FOIL PATTERN for the main PC board if you want to make your own. filament connectors at the base of the magnetron, and with the black test wire still at ground, connect the red lead to either fila- ment connector and push S5. The Microanalyzer should be in the "capacitor test" mode. The "short" lamp should be off, un- less the cathode Is shorted to ground; however, the "capacitor OK" iamp may flash very slowly, indicating that the RF bypass ca- pacitors inside the magnetron are functioning. If the "short" lamp remains off, connect the red and black leads across the fila- ment and push S5; because of the very low resistance of the fila- ment, the "short" indicator will light. If all tests so far have not found the defective component, and the oven still blows fuses when oper- ated, the most likely cause will be an improperly adjusted or defec- tive micro switch. With the oven unplugged, you can use the Mi- croanalyzer as a continuity tester by connecting to each micro- switch and operating the door mechanism slowly, observing that the indicators show open and short as each as each switch goes through its motions. A sticky switch in the wrong posi- tion may cause a short when an- other switch is cycled by opening the oven door. You should also check continuity of thermal switches mounted to the magne- tron or oven cavity, if the oven remains dead. If you suspect the power trans- former, its three windings can also be checked with the Micro- analyzer in the "capacitor test" mode. The primary and filament windings should cause the "short" indicator to light, but the high -voltage winding will cause the "diode open" and "short" lamps to illuminate together, be- cause of the high reverse-EMF generated by the high windings count. Assuming that you have check- ed all components mentioned so far and still have not found any defective components using the static test method, active tests must now be performed. If the oven seems to be working, such as the lamp lights and the fan blows, but there is no heat, addi- tional tests must be done to check whether power is getting to the magnetron. Plug in and turn on the oven; listen for the three-second delay, then the one-second buzz that all magnetrons emit when they fire up. If you do not hear the magne- tron fire, unplug the oven and discharge the capacitor, then connect the red and black test leads across the primary of the transformer. Switch the Micro- analyzer to "volts AC," and power the oven. If there is no voltage reading, there may be a problem with the triac, relay or whatever power-switching system is used. If 120 volts AC is present, the fila- ment voltage should be mea- sured next. Disconnect the high-voltage wire from the filament con- nectors of the magnetron, so that only the filament wires are con- nected and. with the unit in the "AC" mode, connect the leads across the filament connectors and check for 3.1 volts AC when the oven is operated. If there is any corrosion on the terminal connectors, the low- voltage fila- ment current will have trouble lighting the tube. Clean all con- nections with contact cleaner and make sure all connectors are tight. If the problem has not been found yet, we must measure the AC and DC high -voltages. WARNING: this part of the dy- namic test involves measuring potentially lethal voltages so ex- treme care must be exercised. Never exceed 500 volts AC or DC when measuring voltage at input jack J 1. With the oven unplugged and capacitor discharged, con- nect the black test lead to ground, move the red test lead to the HV jack J2, and connect the red test-lead clip to the high-volt- age winding of the power trans- former connected to the high- voltage capacitor. Double check all connections, stand back, and fire up the oven. The AC voltage should be in the area of 1500 to 2500 VAC. If that checks out, turn off and unplug the oven and to m -q -i m m 55 t— — ') o IB a a IMIEfflluU ■ 6 INCHES ■ THE DISPLAY BOARD can be made using this foil pattern. discharge the capacitor, move the red test clip to the other side of the capacitor, and switch the Microanalyzer to "DC." Again, double check connec- tions and fire up the oven. A nor- mally operating oven will have a DC reading initially as high as 4.5 kV: as the magnetron fires up and current is drawn from the power supply, the reading will de- crease to 2—2,5 kV and hold steady. Poor connections to the magnetron will usually show no voltage change, or a changing voltage as the connections make and break. A defective magne- tron will either not fire and the high-voltage reading will remain high, or an intermittently short- ing tube will cause the readings to be much lower than expected. Most better- quality ovens use a triac to power the transformer because they are much more re- liable than a relay, but most tech- nicians do not have a quick and positive way to test them. The Mi- croanalyzer can be used to check the triac. The triac used in a typ- ical microwave oven is usually ei- ther a one-inch square or round package about a half-inch thick with three terminals. The small- est terminal is the gate, or control pin, with the second main termi- nal (MT2) usually in the center, and the common, or first main terminal (MT1) opposite the gate. Pull off the wires from the triac and connect the red test clip from J4 (the semiconductor test leads} to MT2, yellow to the gate, and black to MT1. Indicators LED1 and LED2 should be unlit; a shorted triac will light both LED's. Assuming the indicators are unlit, press test-switch S4: if the triac is switching, both in- dicators will light. If neither one lights, the triac is open and must be replaced. If only one LED lights, either the triac is partially defective, or it is an SCR. If the oven uses a relay, open it and check for pitted or heat- damaged contacts; if required, burnish them, or replace the re- lay. If you believe the problem to be a relay drive transistor, the transistor may be tested by con- necting the red J4 clip to the col- lector, yellow to base, and black to emitter. Initially, LED1 or LED2 may be lit dimly or may be dark, but pressing S4 will confirm the type and proper operation of the semiconductor. For the highest accuracy, the semiconductor may have to be removed from cir- cuit if the readings in circuit are confusing. Triacs and SCR's should never light either indica- tor until S4 is depressed; a triac will light both LED's because it's an AC switching device, while an SCR or transistor will light only one indicator when S4 is pushed. NPN or PNP transistors may ini- tially light either LED1 or LED2, but never both; if LED2 (N-CH) is lit before S4 is pressed, and dims after it is pressed, while LED1 il- luminates, you have just checked a good NPN transistor. You must reverse readings for PNP MOSFET's, usually intimidat- ing to test, are easily checked with the Microanalyzer. Initially, a P- or N-channel device will il- luminate either LED 1 or LED2 re- spectively, and pushing S4 will cause the opposite LED to light, but without causing the original lamp to dim like ordinary bipolar transistors. Ordinary diodes can also be checked; with red at the anode and black at the cathode, LED1 will light. If all components check out so far, but your microwave oven has the symptom of low heating, but otherwise seems to be working normally, check the waveguide cover at the top of the oven cavity at the exit of the waveguide. If it is coated with grease or food resi- dues, it can absorb a large amount of power. Clean it with ammonia and water or, if it's bur- nt, replace it with the same type of plastic or mica material. A mal- functioning stirrer can also cause problems; that can be checked without even removing the oven cover. Stick several NE-2 neon bulbs in a styrofoam cup filled with water, and turn on the oven. A properly operating oven will ionize the neon gas and the neon bulbs will flash on and off as the stirrer rotates. If some lamps remain on while others stay off, the magnetron is good; the stir- rer is inoperative. Check for a broken belt or a seized bearing in the stirrer mechanism. A quick and dirty method of measuring microwave power is to run the oven for one minute at full power with eight ounces of water in a styrofoam cup (re- member to start with cold water); a 500-watt oven will make the water almost too hot to stick a finger in, while a 750-watt unit will cause the water to steam. The final check should be a test of the door seal with a properly calibrated microwave leakage tester. Although the FCC allows five milliwatts per square cen- timeter, most ovens will have al- most unmeasurable leakage. R-E 56 WILLIAM P. RICE LAST TIME WE PRESENTED GENERAL concepts of electric fields and how they are related to static elec- tric charges. We saw that the E field in empty space accounts for the forces between such charges. In this article, we'll see how the familiar units of volts and am- peres are related to each other. Ohm's law and the concept of an E field in materials will be dis- cussed with the help of a simple quantum theory viewpoint. Potential To quasi-statically move a charge q from point a to point b in an E field, a force that is infi- nitely close to being equal and op- posite to the Coulomb force must be applied to q. That force is — qE= — F c i as shown in Fig. 1. As we discussed in our previous article, when moving around a closed path fEdl = 0, or VxE = at all points. So in moving the charge around a closed path -/oE-dl = 0. The dot product gives the magni- tude of force times distance in the direction moved, which is the work done or change in the po- tential energy AU. The energy ex- pended in moving along the path from a to b is just the sum of the contributions along that path, as defined in the calculus notation r b AU ab =- qE-d I (newtonx meters = joules). Ja The energy change is indepen- dent of the path taken from point a to b, and the E field follows the laws of conservation; whatever energy is expended in moving the charge from point a to b is re- covered when the charge moves from b to a. The energy is said to be stored in the E field since the field is responsible for the force. Dividing by the charge gives us the change in energy per unit charge, the potential or voltage at point b with respect to a is -I E- d I (joules/ coulomb = volts). The use of the name potential is perhaps unfortunate because it's easy to confuse the term with po- tential energy. Recall also that since V x E = 0, E must be the gradient of a scaler field, which we now see is the po- tential V, therefore E= -VV (volts/meter = newtons/cou lorn b). Along a surface of equal poten- tial, there would be no change in V per length dl. Perpendicular to that surface the change in V per length would be a maximum, which is what the gradient tells us. Since the field is obtainable by linear superposition, the poten- tial difference is simply the sum of the potentials. For example, V ac =V ab + V b ,. That analysis is the basis of Kirchoffs voltage law, which states that the algebraic sum of the voltage rises and drops around a closed path must equal zero. Electric current Imagine a Gaussian surface in space through which a number of q charges are moving, as shown in Fig. 2. (We are not con- cerned with the type of field influ- encing the motion, only that & there is motion.) The current ^ across that surface is defined as m the charge per unit time (in sec- w onds) crossing the surface. In m order to calculate that, divide the ^ surface into an infinite number 52 57 of infinitesimal surfaces, ds. The charges move with velocity v through each surface. If there are n charges per unit volume, then the current density, or charge per unit area is J = nqv = pv (CVm 2 s). Multiplying that by the effective area and summing the contribu- tions by integration gives the total current I = /J-ds {C/s = amperes). Positive charges flowing in one direction can be considered equivalent to negative charges flowing in the opposite direction (the Hall effect is a common ex- ception) since both J and ds would then be negative. That is why a circuit can be analyzed in terms of either conventional cur- rents or electron currents. The way current is defined is similar to the way we explained electric flux w except that flux is an apparent flow while current is due to an actual flow of charge. Charge conservation tells us that whatever charge flows into the surface must also flow out unless the current density inside is changing in time. That is the basis of Kirchhoffs current law, which tells us that the sum of the currents flowing into a junction is equal to the sum of the cur- rents flowing out of that junc- tion. Shrinking the Gaussian surface down to a single point and taking the ratio of the rate of change in current to the rate of change in volume gives the diver- gence v- j = 4?(C/m 3 s). 03 O o o LU 2 Q < 58 The partial differential symbol d, as in d, means an infinitesimal change in something. It also re- minds us that we're only inter- ested in p's change with respect to time, t. The negative sign indi- cates that a decrease in p, a nega- tive r)p/dt, gives a positive divergence. The net charge must therefore flow out through the surface. Conductivity Up until this point we have been concerned only with charges in empty space. The space of solid materials, however, is far from empty. Atoms are lo- cated at positions called lattice points. An external E field ap- plied to a solid material causes the electrons with a - e charge to FIG. 1— AN ELECTRIC CHARGE q is moved quasi-statically from point a to b in a static E field along either path, com- posed of an infinite number of lengths dl, by an external force qE (not shown). The work done or change in energy is the negative of the sum of all the qE-dl's along the path. FIG. 2— CURRENT DENSITY J is the number of charges q per unit volume mov- ing with velocity v through an infi- nitesimal section ds of the Gaussian surface. The total current is found by sum- ming J-ds over the entire surface. Any charge that comes in through one ds must leave through another. Any net outflow must be at the expense of the charge den- sity enclosed by the surface. ITRMI ENERGY MOMENTUM FIG. 3— ENERGY VERSUS MOMENTUM for electrons in a material. Temperature and lattice effects are neglected. Each electron, represented by a dot on the curve, has a unique energy state. Those are the lowest states available. The high- est occupied energy is called the Fermi energy. move. Quantum theory must be used to describe the effects of temperature and the lattice upon the motion of charges. The electrons are in a state de- scribed by their energy, mo- mentum, and spin. No two electrons can be in the same state. Electrons can change ener- gy only by moving to a neighbor- ing unoccupied energy state. Figure 3 shows the energy versus momentum states, neglecting the effects of temperature and the lattice. The two possible spin states for each electron are not shown for clarity. The more electrons there are in the material, the higher the high- est occupied energy state, or Fer- mi level. Only electrons near the Fermi level can respond to exter- nal effects such as thermal ener- gy and electric fields. Supplying thermal energy excites some elec- trons to energies just above the Fermi level, leaving unoccupied states just below. The Fermi level is then taken as the energy with 50% occupancy. Electrons that can change energy, and hence momentum, are called con- duction electrons. Thermally ex- cited electrons have random momentum and velocity, and do not produce a net current. Electrons act as waves and, therefore, experience inter- ference effects due to interaction with the lattice. At certain wave- lengths, standing waves result which produce energy gaps, as shown in Fig. 4. If only some of the energy states up to the gap are occupied or the gap is very small, the material will have many conduction electrons since little external energy is required to excite an electron to a higher state. Such materials are good electrical conductors. A good in- sulator (or dielectric) has oc- cupied states up to a relatively large gap. A large amount of ex- ternal energy is required to excite electrons to higher energies in a dielectric material. A material with a large gap and many oc- cupied lower states exhibits no- ticeable electrical resistance. If a potential difference is maintained across a material, an electric field is established. Con- duction electrons will be sub- jected to a force F, which is equal to — eE. Electrons tend to acceler- ate, and then "collide" and lose energy to the lattice. If t is the average time between collisions, which is temperature dependent due to thermal motion of the lat- CONDUCTOR ENERGY INSULATOR ENERGY A i ,y r GAP i , '\ y , 1 ) i i 1 GAP V / , MOMENTUM a MOMENTUM b FIG. 4— ENERGY VERSUS MOMENTUM lor electrons is a lattice of atoms. The gaps in the curves result from interference effects with the electron waves. In a conductor (a) the levels below the gap are partially occupied. External energy excites electrons to the unoccupied energy states. That allows them to participate in an electric current. In an insulator (b) the levels below the gap are filled and the energy gaps are large. Electrons cannot participate in a current unless a large amount of external energy is supplied. tice atoms, then the average elec- tron momentum is Ft= -eET = m + v (N-s = kg-m/s) where m is the electron mass, and v is the average velocity. Solv- ing for the velocity and substitut- ing into the equation for current density gives us m which is the vector form of Ohm's law. Since the number of elec- trons n and t are properties of the material, the conductivity n = ne^/m (C 2 s/kg = 1/{ftm) is a property of the material. The resistivity is defined as r = l/cr. If the material is of uniform cross- sectional area S and of length L, J is uniform and normal to ds, therefore the current is l« JS = 0j- S or V = IR where R = rL/S is resis- tance in more familiar units of ohms. In metals, increasing the ther- mal energy excites electrons mainly into the unoccupied states of the lower band, but the time between lattice collisions decreases. Increasing the tem- perature increases the resis- tance. In some other materials resistance decreases with in- creasing temperature because the number of conduction elec- trons exceeds the effect of in- creased collision time. Due to the low velocity of elec- trons in most solids, the magnet- ic effects can be neglected. Conduction becomes more com- plicated in gases and liquids since the atoms can also move, and velocities can become greater than in solids. The electric field in materials When a material is placed in an external electric field E , the wave functions of the atoms are changed. The net effect is that INSULATOR ©-© H — E| -*. E. FIG. 5— MATERIALS IN AN EXTERNAL ELECTRIC FIELD E exhibit electric polarization. The resulting separation of positive and negative charge regions produce electric dipole moments qR. where q is taken as positive. In a conductor (a), enough electrons are free to move to create a depolarization field E d equal and opposite to E . The internal electric field E, E„ E d is zero. In an insulator or dielectric (b), electrons are restricted in movement and E, is non zero. In both cases, the polarization or dipole moment per unit volume P is related to E d . The vectors are shown outside the material for clarity. the regions with probability of finding electrons are shifted in the -E direction while the re- gions with probability of finding the positively charged nuclei are shifted in the direction of + E D (Fig. 5). The shifts may not exact- ly align parallel to E . and may not all be uniform except in what we call simple materials. A nega- tive surface charge develops on the material near the source of E„, and a positive surface charge develops on the opposite side. We say the material has an induced charge, or that it is electrically polarized. The induced charges produce a field E d in the opposite direction to E in the material. In a very good conductor, there are enough free charges so that E d equals E Q , and the average field inside is zero. That is why metal is an effective shielding material, at least for static fields. Outside the conductor the E field vectors are changed so that they are nor- mal to the surface. In dielectrics, the large energy gap means the electrons are elas- tically attached to the lattice and only slight shifts are experi- enced. E and E d don't cancel each other completely. In a simple dielectric, pairs of internal charges, — q and +q, are sepa- rated by a distance R taken in the direction of E , from -q to 4-q. Those pairs of negative - q and positive +q charges are called electric dipoles. The vector quan- tity, qR, is called the electric di- pole moment. If there are n dipoles per unit volume, then a measure of the polarization can be expressed as P=n(qR)£ (Cm/m 3 = C/m z ), which is called the dipole mo- ment per unit volume, t, is a function of the alignment and ranges from to 1. For simple materials £=1. Since n, q, R, and £ depend on the material, P = e xE where x, the electric suscep- tibility, is a measure of the ease of polarization of the material. E is present to maintain correct units. The so called depolariza- tion field E d is equal to -7P/e , where 7 is a number between -** and 1 , and is related to the geom- 3 etry of the material. E d is not, in 1 general, very useful. ro The surface charge rr b is an ac- id tual accumulation of charges ^ con tin ued on page 82 ^ 59 m y z Q EC F o Q If your home or office has more than one telephone extension, you've probably had the unpleas- ant experience of picking up the phone only to find it already in use. You may get an angry re- sponse from the person on the other end. If a modem is in use, you'll be greeted by the obnoxious squall of two computers ex- changing bits. Such an interrup- tion usually means a lost connection, or the corruption of a file being transferred. A solution to that problem is the Phone Sentry — an inexpen- sive, simple, reliable indicator that warns you when a phone ex- tension is in use. The Phone Sen- try is easy to build and install in one evening, and presents no load to the phone line. It's small, inconspicuous, and costs only $5 a copy. How it works To understand how the Phone Sentry works, you need to under- stand how the telephone system works — or, at least, how the local subscriber loop works, since that's the part that enters into your house. The telephone line is held at about 45 volts DC by the local switching office when it's hung up. When a telephone is taken off its hook, a IK load brings the line down to 6 volts DC. The line stays at 6 volts DC until you hang up, then it returns to 45 volts DC and is disconnected. The Phone Sentry operates by monitoring the telephone line voltage and switching on a flash- ing LED whenever the voltage drops below 20 volts. The Phone Sentry can be placed anywhere on a phone line, not Just on an extension in use. Circuit operation The Phone Sentry circuit is de- ceptively simple, yet elegant in design. At the heart of the circuit is IC1, a CMOS CD4093B quad nand gate Schmitt trigger. Ordinary CMOS gates switch midway between the voltage of the positive and negative sup- plies. For a circuit powered from 5 volts, this point (called 0,5 V + } is 2.5 volts. When the input volt- age rises past or falls below that point, the output will switch. Normally, that's a desirable characteristic, and is one of HE PHOIXI EIMTR "Stop! Don't pick up that phone!" The Phone Sentry will warn you when a telephone extension is in use. DANIEL B. COOPER fltrt*,fff"t*tr*tf" CMOS's good points. However, when a CMOS input is presented with a slowly changing or noisy input, the symmetrical switch- ing characteristic can cause the circuit to jitter or oscillate as the input nears the 0.5 + V point. The Schmitt trigger input han- dles noisy environments by sepa- rating the rising and falling voltage-switching points. A Schmitt trigger input will react to a rising input voltage only when it passes a threshold that is higher than 50% of the supply voltage, usually about 70%, or 0.7 +V. A falling input voltage will cause a change only when it falls below a much lower thresh- old of about 30% of die supply, or 0.3 + V. An input voltage between those two thresholds will have no effect until it rises above 0.7 + V, or falls below 0.3 +V. The region between the 70% and 30% switching levels is called the hysteresis gap, or dead band. Hysteresis permits a Schmitt trigger input to respond very cleanly to noisy or irregular input signals. It also permits some fancy tricks, such as one- gate oscillators. It is the latter ca- pability for which a Schmitt nand gate is used in the Phone Sentry. Figure 1 shows a block diagram of the Phone Sentry. The four gates of the CD4093B are used as three separate elements. One Schmitt-trigger nand gate acts as an input comparator to monitor a phone line. It in turn gates an- other nand gate used as an os- cillator, which drives a high- current buffer for LED1. The schematic of the Phone Sentry is shown in Fig. 2, with its circuit waveforms at critical loca- tions shown in Fig, 3. Bridge rec- tifier Dl — D4 eliminates any phone-line polarity problems. It also removes the 80-volt peak-to- 60 peak ring signal, which could damage the Phone sentry or make LED1 flicker. The output of the bridge rec- tifier is divided down by R1-R2, with 27% of the input voltage reaching ICl-a. 27% represents the voltage divider of the [R2/(R1 +R2)] ratio, which equals (1 megohm/[1 megohm + 2,7 megohm)] = 0,27 The bridge always presents two of the four diodes as a phone-line load, D1-D4 or D2-D3, dropping the line voltage down by 0.7 volts DC each, or 1.4 volts total. Since the input impedances of pins 12 and 13 of ICl-a are almost infi- nite, they draw no current. What appears across Rl and R2 in se- ries should be about 45 V- 1.4 V = 43,6 V. The voltage at pins 12 and 13 with the phone hung up is there- fore 43.6 Vx 0.27 = 11. 78 V, which is 2.78 volts above the 9- volt DC supply. The IC, however, is protected from overcurrent burnout by Rl and internal di- odes. When an extension is in use, the 6 volts on the line goes down to (6 V- 1.4 V) x 0.27 = 1.24 V. Capacitor CI filters out small spikes that can be generated dur- ing the ringing cycle, protecting the IC and eliminating any re- sidual tendency of the LED to flicker. Because the comparator is a Schmitt nand gate, its output (pin 11) will be low whenever the input voltage is above about 6.3 volts (70% of 9 volts), and high whenever the input drops below about 2.7 volts (30% of 9 volts). Those switching values fit per- fectly with the 11,78 and 1.24 volts generated from the phone line by the rectifier and divider. The output will be low when all phones are on-hook, and high when any phone is picked up. or a modem is connected to the line. The LED could be driven di- rectly by ICl-a, but Bl would be drained in about 10 hours be- cause LED1 draws 10 milliamps when lit. To extend battery life to at least 100 hours. ICl-b, the low 5% duty-cycle oscillator, is gated bylCl-a, driving LED land giving a bright flash with much lower current drain. The output of the comparator is used to gate an oscillator on and off. That oscillator consists BRIDGE SCHMITT-TRIGGER TIMING RECTIFIER COMPARATOR GATED DRIVER INDICATOR OSCILLATOR FIG. 1— BLOCK DIAGRAM OF THE PHONE SENTRY. The rectified phone-line voltage drives a comparator, whose output gates a low duty-cycle oscillator. The oscillator drives a CMOS buffer/driver. The period and duty cycle of the oscillator are controlled by timing components R3, R4. and C2. R1 2.7MEG FIG. 2— SCHEMATIC OF THE PHONE SENTRY, using a CD4093B quad NAND-gate Schmitt trigger. The green (tip) and red (ring) phone-line wires are polarity-independent due to D1-D4. Input comparator IC1-a gates ICt-b, a single-gate oscillator, which drives ICI-c and -d, used in tandem as a high -cur rent buffer/driver. PARTS LIST All resistors are Vi-watt, 5%. R1 — 2.7 megohms R2— 1 megohm R3— 4.7 megohms R4— 220,000 ohms Capacitors C1—-0.005 p.F. 100 volts, disc or monolithic C2— 0.33 (jlF, 16 volts, tantalum or electrolytic Semiconductors D1-D4— 1N4001 diode D5—1N4148 diode 1C1— CD4093B quad Schmitt trigger NANo-gate LED1 — light-emitting diode, any size or color Miscellaneous: 9-volt alkaline battery with clip, PC board (see foil pattern), 22- AWG wire, plastic case (optional), LED mounting clip (optional), modular plug- to-bare wire phone cable (optional), two-way phone jack duplexer, 14-pin D!P IC socket. both inputs are now high, the output switches low. The charge of C2 is drained, partly through R3, but more quickly through R4 and D5. When the voltage at pin 1 drops below the Schmitt input's <£ lower threshold, the output of ^ the gate switches high, and the cjj capacitor begins charging again ro through R3. When the capacitor 3 voltage reaches the Schmitt's up- 5 per threshold, the output switch- 2 THE PC-BOARD FOIL PATTERN FOR the Phone Sentry. of a second Schmitt nand gate (ICl-b). R3, R4, C2, and D5. When pin 2 of IC1 is held low by the comparator, the output of the gate is held high. That output is used to charge timing capacitor. C2, through timing resistor R3. The junction of components R3 and C2 is connected to pin 1. With the output held high, the charge on C2 will rise to the level of the supply voltage. When a phone is picked up and the loop voltage drops, the com- parators output goes high and the oscillator is enabled. Since 61 m o z O E ts LU _l UJ Q Q < EC 43.6 PHONE LINE, VDC (ON-HOOK) 4.6 (OFF-KOOK) , , IC1-a PINS 12 AND 13, VDC (RELATIVE TO CIRCUIT GND) 11.78 9-t 2.7 t.244- — * PROTECTED BY HI AND INTERNAL if-i-api : DIODES IN 1 ' IC1-a g VDC FIG. 1— CIRCUIT WAVEFORMS OF THE Phone Sentry. Shown are the voltages on the phone line, pins 12 and 13 of IC1-a, pin 11 of IC1-a, pin 3 of IC1-b, pin 1 of ICI-b (the voltage across C2), and across LED1. I r-i L^, - R3— ™ 4«w -C2- + _ R4 _^_ PHONE LINE ■Jrf# FIG. 4— THE PARTS PLACEMENT DI- AGRAM of the Phone Sentry. You can mount LED1 In several ways, depending on how you mount the PC board. es low again and the process repeats until the gating input is again brought low by the phone going back on-hook. The output of the oscillator (pin 3) is inverted and used to drive the indicator LED. When the oscillator's output is high, the output of the driver (pins 10 and 4) is low, and the LED is off. When the oscillator output is low, the driver output is high, and the LED is on. Since the capacitor discharge time (oscillator output low) is much shorter than the charge time (oscillator output high), the LED is on much less time than it is off, resulting in a very low duty cycle, and low bat- tery drain. Because the capacitor starts each cycle charged much higher than the Schmitt input's upper threshold, it takes longer to dis- charge to the lower threshold the first time. Therefore, the first flash of the LED is longer and brighter than those that follow. That's a nice touch, because all of the Phone Sentries in the house will give an initial bright flash when a phone is first picked up to answer a call. Construction and installation The Phone Sentry can be as- sembled on either a PC board, shown here, or on perforated construction board of similar size. The PC board is about the size of Bl, so housing the unit is simple, and its construction is straightforward. Figure 4 shows the parts placement diagram; use a socket for 1C1, and install it using proper anti-static han- dling techniques. The Phone Sentry is small, with several installation options. Once you decide how to mount it, you can select how to wire both the phone line and LED1. If you put the Phone Sentry inside an extension or a wall-mount jack, then solder a foot of 22-AWG wire to each input terminal. If you use a small case for plug- ging into a wall socket, solder the green (tip) and red (ring) wires of a modular plug-to-bare-wire phone cord, and clip the yellow and black wires. You may want to solder LED1 directly to the PC board, or mount it in a visible location with two 6-inch pieces of stiff wire. You can mount both the PC board and Bl in a standard desk phone. Open the phone and se- cure both the PC board and bat- tery clip to the baseplate with double-sided foam tape. Drill a small hole in the dialing button escutcheon, and use silicone sea- lant or an LED clip to mount LED1. Connect the two input wires to the tip and ring wires, insert Bl, replace the cover, and plug the phone back in. If there's no space for the Phone Sentry and Bl, use a small plastic box on the side of the phone for the PC board, Bl, and LED1, and pass the tip and ring wires through a hole in the box and phone case to the connecting points inside the phone. For a wall phone, mount the same case near the wall jack and run the wiring into the wall jack, so it's independent of the phone. R-E 62 ITS BEEN LESS THAN A DECADE sense the compact disc was in- troduced. In that short time, the CD has brought high-quality au- dio reproduction to the masses. and taught us to appreciate good sound. We're not exaggerating when we say that the CD has changed the way we listen to mu- sic. It's rare for a new technology and format to catch on so quick- ly — especially one that threatens to make its predecessors ob- solete. CD was a success not only because of consumer acceptance , but because it also offered some- thing to manufacturers, record- ing companies, and retailers. It wasn't the CD's "gee whiz" appeal — nor was it the promise of perfect audio reproduction — that caused sales to catch fire. It was convenience. When compared to the LP that it replaced, CD's were a dramatic breakthrough. They can store more audio in a pack- age a fraction of the size. They can be lent to even your most careless friends without getting scratched. They even play back more conveniently, because you can skip tracks that you don't want to listen to, or re-arrange the order in which the songs play back. It's convenience, also, that makes the venerable compact cassette our music medium of choice. {Cassettes outsell CD's by a ratio of about 1.5:1.) They fit in your shirt pocket, and they stand up reasonably well to abuse. They're ideal for use in a car or in a personal stereo because they're relatively immune to shocks. So what if they can't come close to the audio quality of a CD or even an LP? How about DAT? In the belief that consumers had fallen so much in love with the idea of digital audio because of their exposure to CD, Japa- nese manufacturers reasoned that Digital Audio Tape (DAT) would be to the CD what the com- pact cassette was to the LP. Unfor- tunately, it didn't work out that way for a number of reasons. First, the record industry, spearheaded by the RIAA (Re- cording Industry Association of America), threatened lawsuits against any Japanese manufac- turer who exported the DAT ma- Two new digital audio formats — Sony's Mini Disc and Philips' Digital Compact Cassette— promise to battle each other as they create consumer confusion. chines to the U.S. The RIAA was concerned about DAT's potential to make virtually perfect copies of CD's. (They seemingly missed the fact that, for most people, cas- settes do the same thing. And de- spite that, pre-recorded cassettes have outsold both LP's and CD's combined since 1982! They've outsold blank tapes as well.) The threats of lawsuits were enough to stop DAT dead in its tracks, despite considerable accolades for the format in the audio and general press. Although some DAT machines were available on the "gray mar- ket" of unofficially imported goods, DAT officially arrived in the U.S. market last year — with generally disappointing results. Whether it was the years of delay, the taint of the lawsuits, the ex- pense of the machines, or the lack of pre-recorded software that have killed DAT in the consumer market, we'll never know for sure. Perhaps DAT failed because 09 m m CD m x — . to 63 107.5 o z i O LU Q D < 8x1 - 185 95=1560 10 | 1 z 3 4 5 6 Li 7 8 1852,5 HEAD ROTATION EIGHT TRACKS OF MUSIC DATA are con- tained on each "side" of the Digital Com- pact Cassette, as shown in a. (All dimensions shown are in micrometers.) The DCC head shown in b is manufac- tured using thin-film techniques. It con- tains a set of 8 digital recording and playback heads as well as two analog playback heads, it doesn't offer the avarage con- sumer anything that they're not already getting from their favor- ite compact cassettes. Although the compact cas- sette- — even with its inherent problems — is just fine for most people, Philips, the originators of the compact cassette, was con- vinced that the format could be improved, and that consumers would buy into the updated for- mat. Thus. DCC, the Digital Compact Cassette, was born. Enter DCC In January of this year. Philips announced that "a new era of au- dio reproduction has started." DCC, a digital extension of the compact cassette, would offer "the best opportunity available for consumers and industry to enter into the field of digital re- cording." Tandy Corporation an- nounced that they would be the first U.S. licensee of Philips' tech- nology, and would introduce a home recording deck in late 1992. The most Important feature of DCC is that it doesn't make the familiar cassette obsolete. All DCC players will play back exist- ing analog cassettes, so even when you make the jump to DCC, you can still listen to your exist- ing library of tapes. (You won't, however, be able to record analog cassettes on your DCC machine, or play DCC tapes on your stan- dard cassette deck.) That "back- ward compatibility" could con- vince some consumers to up- grade to DCC even though they like what they already have. After all, an upgrade won't just give them better sound, but as well see, more convenience as well. A DCC deck is essentially a standard cassette recorder that includes some extra digital elec- tronics and a new head design. The dimensions of a DCC cas- sette are essentially the same as that of a standard cassette, but the digital cassette's sides are flat — the case doesn't get fatter where the head enters the shell. Also, since the DCC standard de- mands that all DCC players fea- ture auto-reverse, there's never a need to flip the tape over, so you don't need to have holes for the reels on both sides of the cas- sette. That means that one full side of the cassette can be used for information and graphics — something the recording compa- nies love. The spool holes and the tape surface are protected against dust and fingers by a sliding met- al cover, which also locks the tape hubs. There's no need for an car- rying case, so the digital cassette is easier to use and store, es- pecially in a car. The key to maintaining com- patibility with standard cas- settes is a new thin-film semicon- ductor head, manufactured using a process similar to that used for integrated circuits. The first layer of the head contains one set of 9 magneto-resistive heads for digital playback, and a pair of similar heads for analog playback. On the second head layer is one set of 9 integrated 0.02 05 1 H.'z 0.5 i 2kHz 5 tfj~20 FREQUEMCY-kHz 100 80 60 t 20 0.02 0.05 0.1 0.2 0.5 1 2kHz 5 10 20 FREQUENCY-kHz - 0.020.05 0.1 0.2 0.5 1 2kHz 5 FREQUENCY-kHz 10 20 PHILIPS' PASC ENCODING ignores sounds that are below the hearing thresh- old (a). Of the signals shown in b, oniy A would be recorded because B, below the hearing threshold, would not be heard. The hearing threshold, however, varies dynamically depending on what other sig- nals are present, in c, signal B has altered the threshold, making A inaudible. recording heads for digital re- cording. Well see shortly why 9 digital heads are required. PASC makes it work The key to the DCC system is the a new digital coding tech- nique called PASC, or precision adaptive sub-band coding. The goal of PASC is to produce a sig- nal equivalent to that of a CD. The results? A dynamic range better than 105 dB, and a total harmonic distortion, including noise, of less than 0.0025% PASC is based on two impor- tant phychoacoustic principles. The first is that we can hear sounds only if they're above a cer- tain level, called the hearing threshold. The second is that loud signals mask soft ones by raising the hearing threshold. 64 The hearing threshold, as you might expect, varies from person to person. Even a very sensitive ear, however, won't be able to hear a sound if it is masked by a louder sound. (You couldn't, for example, hear an unamplified vi- olin at a rock 'n' roll concert! ) The theory behind PASC's efficiency can be expressed by the ques- tion, "If you can't hear it, why record it?" During encoding, the PASC processor analyzes the audio sig- nal by splitting it into 32 sub- band signals. By continuously taking into account the dynamic variations of the hearing thresh- old, the PASC processor encodes only the sounds that will be audi- ble to the human ear. Each sub- band is allocated the number of bits that are required to accu- rately encode the sound within it. If a subband doesn't require my bits — because it contains sounds that are masked, for example — its bits are re-allocated to other subbands so that the sounds within them can be encoded more accurately. On average, the PASC system needs to encode only one quarter the number of bits that a CD or DAT encoder would to reproduce a given audio signal. The encoded data is multiplex- ed into an 8-channel data stream, and error-detection and - correction codes are added. The eight channels are recorded on 8 parallel tracks on the DCC tape. The ninth track can be used to carry auxiliary data, such as song titles, recording times, and the like). The auxiliary track could be used to generate hun- dreds of characters of text per TERBIUM FERR1TE COBALT MAGNETIC MATERIAL POLYCARBONATE RESIN A PROTOTYPE MINI DISC player and a pre-recorded disc. ALUMINUM REFLECTIVE LAYER PROTECTIVE LAYER THE MINI DISC is composed of 4 layers. second, so decks could include readouts for song lyrics or other information about the selection. DCC, an elegant extension of the most popular music carrier we have, seemed to be a sure-fire hit. It had something for every- one, including hardware man- ufacturers, record companies, retailers, and consumers. It now appears, however, to have run up against a formidable competitor: Sony's Mini Disc. Sony's Mini Disc In May of this year, in what seemed to be a deliberate attempt to derail DCC before it got mov- ing, Sony announced a brand new recordable audio format, the Mini Disc or MD. Sony, however, denied that their MD was meant to compete with DCC. In re- sponse to the question of what MD replaces, the President of Sony Corporation of America an- swered "We are replacing nothing. We are Creating new markets." The Mini Disc format is specifi- cally designed for portable ap- plications (personal stereos, boom boxes, etc.) and is slated for introduction, conveniently, in late 1992 — the same time that DCC decks are due. The disc, about 2'/2 inches in diameter, looks — -and acts — like a cross be- tween a compact disc and a micro floppy computer disk. Like a compact disc, the Mini Disc is an optical medium — it is read by a laser and can store up to 74 min- utes of digital audio. Like a floppy disk, the mini disc can be mag- netically recorded again and again. How did they manage to get the same capacity as a CD on a disc that has about l A the surface area? Interestingly, by treating audio in much the same way as DCC does. Sony's encoding scheme, which is called ATRAC, or adaptive transform acoustic coding. Is also based on the psy- choacoustic principles regarding the threshold of hearing and the masking effect. Because the ATRAC encoder ig- nores sounds that fall below the threshold of hearing (which var- ies dynamically because of signal masking) it can encode data five times more efficiently than CD or DAT systems. That's even better than DCC's 4:1 advantage! Can a recording that "leaves out 80% of the bits" sound as good as a CD? In theory, if all you're leaving out is things you can't hear, then yes. In practice, we don't know yet. At Sony's an- nouncement, they demonstrated a prototype by playing some pop/ rock for a half minute or so. It sounded OK, we guess, consider- ing that the listening environ- ment was a crowded hotel meeting room. No A/B com- parisons were provided between CD and MD. Sony claims that "only 2% of the population will be able to hear the difference." The Mini Disc is constructed of four layers, including a newly de- w veloped magnetic layer of ter- S bium ferrite cobalt. Since mag- m ne to-optical discs can't come in §5 contact with the recording 3 heads, it's important that the — magnetic material be able to 2 65 CTj u z o LU 6 Q < a: MAGNETIC HEAD WRITING SIGNAL 1 1 1 1 t ) ( DISC ROTATION NEW OLD CEEEEEI tl*l#f!W MO LAYER [CROSS-SECTIONAL VIEW OBJECTIVE LENS LASERt MAGNETO-OPTICAL OVERWRITE TECHNOLOGY. When the magnetic layer is heated by the laser, it becomes possible for the magnetic head to change its polarity. The polarity is then detected by the laser during playback by noting the direction of reflection. change polarity when subject to a very small magnetic field. The new material fills the bill. The Mini Disc requires both a laser and a magnetic head for re- cording. When the magnetic layer is heated by the laser (to a temperature of about 400°F), it loses its coercive force — that is, it becomes very easy to magnetize. The head then supplies a mag- netic field to set the material's magnetic polarity. When the heated spot cools, the new polar- ity is "locked in" and, thus, the digital data are recorded. Sony's Mini Disc has a couple of advantages over other optical recording methods. The struc- ture of the head is much simpler because the laser can be on con- tinuously during recording and playback. And the low-coercivity of the magnetic material greatly reduces the power required, making portable operation feasi- ble. One feature of Mini Disc touted by Sony is that the portable Walk- man players will have "shock- proof memory. " One of the prob- lems with current portable CD players is that they don't work too well unless they're standing still. Any sharp jarring causes the laser to mistrack. Mini Disc players shouldn't suffer from that problem because data is read off the disc at a rate far faster than required by the ATRAC de- coder, creating a data buffer of MINI DISC 1.4 MBIT/SECOND- -L ^ A OPTICAL PICKUP 1 MBIT MEMORY ~a second CAPAcmt 0.3 MBIT/SECOND _ I I l DIGITAL MUSIC DATA [DECODER \ □ ANALOG MUSIC L< | SIGNAL SHOCK-PROOF MEMORY promises to make Mini Disc an ideal portable format. Since the data is read off the disc far faster than required by the ATRAC decoder, a butter as long as three seconds Is created. three seconds. If the laser mis- tracks, the listener won't hear it. The buffer will feed data to the decoder while the laser finds its way back to the right spot. Sony's announcement included a dem- onstration where a prototype player was shaken vigorously without any audible result. The prototype continued to play even after the disc was removed until the 1-megabit buffer was empty! Of course, there's no tech- nological reason why portable CD players couldn't offer their own shock-proof memory buffer. But since the buffer would have to be 5 times the size, it would add greatly to the cost. Who wine? Ever since we forecast that DAT would be a sure-fire success, we've been reluctant to make pre- dictions. But let's look at some of the issues involved, and how DCC and MD stack up. For consumers — assuming that both formats offer high- quality audio — -DCC has the de- cided advantage in that existing libraries of cassettes won't be ob- solete. Both formats have the po- tential to supply such con- venience features as song title and lyric readouts, but MD offers much faster random access of tracks Although it's too early to say for sure, prices for home DCC decks should be under $500 when introduced, while a porta- ble MD player is expected to cost around $400. For consumers, we give DCC a slight edge. The recording companies will have a hard time taking sides. Both technologies will use the se- rial copy management system or SCMS, an anti-piracy system. Manufacturers will be able to du- plicate DCC at 64 times normal speed on equipment similar to what is now used for standard cassettes. Mini Disc players will be able to play back not only mag- neto-optical discs, but pre-re- corded optical discs as well — discs manufactured using the same process as is used for CD's. Various recording companies have expressed support for each format. Which way will the record companies go? For us, it's too close to call. Hardware manufacturers should prefer DCC because stan- dard tape transports can be used. Retailers, always reluctant to have to stock the same titles in various formats, are dreading the thought of re-vamping their stores to accommodate either DCC or MD. What about you? In the long run — since both formats seem destined to compete with each other for your money — it's you who will decide whether DCC or MD is the personal recording for- mat of the 90's and beyond. R-E 66 EEEEZiaffiEi Driving inductive loads, more on phone caller ID, Bakerizing and laminating, alternators as stepper motors, and programmable logic resources. DON LANCASTER Let us first pick up on several updates to some of our earlier Hardware Hacker topics. One good source for those BA1404 FM stereo broadcasting kits is DC Elec- tronics. They also stock the super new Signetics NE602 mixer/convert- er chips and the TEC-200 film for di- rect toner printed circuits. Another NE602 source is Active Electronics. Telephone caller ID is certainly one hot topic these days. And yet another source of call identifier magic boxes is Hello Direct. Prices start at $60. You must, of course, have the ID ser- vice available before you can use these magic boxes. States that have at least some local availability of caller !D should now include AL, CA, FL. GA, IL, IN, MD, ME, Ml, NC, NE, NJ. NV, OH, OK, SO TN, VA. VT, VW. and Washington DC. Other areas are Still in the planning stages. Most ser- vices are still for local calls only. One handy and rather non-obvious benefit of this new service: When you come back from lunch, you have a complete and time-stamped list of ev- eryone who tried to call you when you were out. Most useful. I thought we might round up a big collection of odds and ends for this month's column... Driving inductive loads If you blindly connect a transistor or another solid-state device to an inductor such as a relay or a motor coil, you will almost certainly blow out your circuit the very first time you power it up. Special protection tech- niques are always needed when you try to control an inductor's current with any solid-state device. These in- ductive-circuit protection techniques are cheap and simple, but you do have to understand what is coming down to use them properly. Take a coil of wire and connect it to a voltmeter. Now shove a magnet through the center of your coil. As you insert the magnet, you generate a positive induction voltage. Remove the magnet, and you'll generate a negative induction voltage. Any time your magnetic field changes, you generate an induced voltage. And the faster the change, the more voltage you create. Since any current through a coil can generate a magnetic field, any change in your coil current should produce a change in the magnetic field, which in turn induces a voltage spike. The greater or the more sud- den the change in the current, the greater the induced voltage. The basic math here says that: e = LAi/At or, in plain English, your induced volt- age across any coil is proportional to the size of the inductorand the rate of change of current through the coil. Say you decide to control a relay. You turn your relay on by sending a current through your coil. And then you attempt to turn your relay off by suddenly disconnecting your coil cur- rent. What happens? Your magnetic field will suddenly collapse, generating a horrendous voltage spike. You tried to make At zero, and, since you're now trying to divide by zero, you get a theoretically infinite voltage spike. Thus, suddenly ceasing the current in any inductance is guaranteed to create a humongous voltage spike. Sometimes you might choose to purposely do that. For instance, the current through the coil in any car ignition is suddenly broken to step up the 12-volt battery into many tens of NEED HELP? Phone or write your Hardware Hacker questions directly to: Don Lancaster Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 thousands of volts of ignition-spark voltage. And a related technique gets used for television high-voltage. But. should you suddenly cease a current through any coil in any solid- state circuit, the voltage spike you'll get is almost certain to blow up the transistor of whatever happens to be controlling your coil. The rule here is simple: Never let the current through an inductive load suddenly drop to zero in any solid- state circuit! Figure 1 shows you how to add a plain old power diode to your relay coil to provide spike protection. Note that the diode appears "backward" so that it does nor normally conduct any supply current. If you suddenly try to turn off the inductor current, a small induced volt- age will immediately be created that, in turn, forward biases and turns on the protection diode. The current you had before can then continue on through your protection diode and back into the relay coil. The current will now drop down to zero fairly quickly, dissipating itself in the for- ward drop of the diode and in the internal resistance of your relay coil. At no time is any voltage spike gener- ated that exceeds the 0.6 volts or so of your diode's forward drop. This simple diode despiker works quite well. But there are some minor side effects that can sometimes cause problems. Note that your relay will stay pulled in for a brief time delay after you thought you turned if off. That happens because there is still diode- provided current going through your coil. In a larger relay, the time delay could extend a few tenths of a second, and could cause you timing problems. The physical dropout of your relay „ can also end up slower and sloppier. ^ Which could cause contact arcing in m higher-current uses. § Your protection diode should also 3 turn on fairly fast. If you use a slow ^ diode, or if there is not enough stray iS 67 INDUCTIVE LOAD [0-W1V ± DESPIKING DIODE INDUCTIVE LOAD Hp FIG. 1— ANY SEMICONDUCTOR can be in- stantly destroyed if you use it to suddenly turn off the current in an inductive load. The despiking diode shown here allows the coil current to continue long enough to safely dump the magnetic flux energy without creating a killer transient. circuit capacitance around, a large and possibly destructive spike can build up during the time your diode actually starts conducting. Figure 2 shows you an improved spike-protection circuit. Here we have added a 24-voit Zener diode in series with the protection diode. This combination will conduct no current in one direction and will conduct in the other direction only when the volt- age across it exceeds the Zener breakdown of 24 volts. You can think NEW FROM DON LANCASTER HARDWARE HACKER STUFF Hardware Hacker Reprints II or II] 24.50 Midnight Engineering Reprints 16.50 Incredtble Secret Money Machine 12.50 CMOS Cookbook 24.50 TTL Cookbook 19.50 Active Filter Cookbook 19.50 Micro Cookbook vol 1 or II 19.50 Lancaster Classics Library 109.50 Enhancing your Apple 1 or II 17.50 AppleWriter Cookbook 19.50 Absolute Reset He & He 19.50 Enhance 1 or II Companion Disk 19.50 AppleWriter CB or Assy CB Disk 24.50 POSTSCRIPT STUFF Ask The Guru Reprints 1, II or III 24.50 LaserWriter Secrets (lle/Mac/PC) 29.50 PostScript Show & Tell 39.50 Intro to PostScript VHS Video 39.50 PostScript Beginner Stuff 39.50 PostScript Cookbook (Adobe) 16,50 PostScript Ret. Manual 11 (Adobe) 28.50 PostScript Program Design (Adobe 22.50 Type 1 Font Format (Adobe) 15.50 LaserWriter Reference (Apple) 19.50 Real World Postscript (Roth) 22.50 en PostScript Visual Approach (Smith; 22.50 O Thinking in PostScript (Reid) 22.50 z o The Whole Works (all PostScript) 299.50 rr o FREE VOICE HELPLINE VISAfMC ill SYNERGETICS LU 6 Q < Box 809-RE Thatcher, AZ 85552 (602) 428-4073 DESPIKING DIODE ENERGY- DUMPING ZENER INDUCTIVE LOAD [^o-JyWV- -§ FIG. 2— ADDING A SERIES Zener diode shortens and sharpens the dropout time. This minimizes turn-off delay and contact arcing in power relays. Your control tran- sistor must be able to block the supply voltage PLUS the Zener voltage. of this series combo as an "inefficient diode" with a 24-volt forward drop. Whenever you suddenly discon- nect your relay current, a large but acceptable 24-volt high-voltage spike is created, which turns on both di- odes in the series pair. The current continues through the diodes, but will fall to zero much faster as you now have a 24-volt drop burning up all of your remaining coil energy. Thus, the circuit will still give you protection, but will shorten the excess holding time by a factor of 40 or so. Your contact release will also be that much faster. What happens is that you've now made a tradeoff. You are allowing a reasonably sized spike in exchange for a big reduction of the release time. Note that your transistor will see a maximum voltage of your supply volt- age plus the drop of the Zener during break time. For instance, on a 12-volt supply, your transistor would have to block at least 36 volts if it is not to be damaged. There are special back-to-back Zener-like components intended for spike protection. They go by the names of varistors, MOV's, or transient protectors, and do have various brand names. They work the same way as Fig. 2 in that they do not conduct until spike time. Then they do conduct heavily and internally dis- sipate the inductor's flux energy. Fig- ure 3 is a typical circuit. SGS is one of many suppliers of the TRANSIL spike protectors. Their BZW04P23 is typical. At 25 volts or under, it draws only 5 microamps. Above 30 volts it starts conducting heavily, and by 41 .5 volts it draws at least 10 amperes. Despite the tiny package, these devices can with- stand 50 amps for 10 milliseconds. Higher-power units are also available. A TRANSIENT PROTECTOR o-W/t- FIG. 3— TRANSIENT SUPPRESSORS are commercially available bi-directional de- vices that are also known as varistors, MOV's, TRANSILS, or several other trade names. These must be carefully matched to the allowable voltage rise and the mag- netic flux energy to be dumped. You do have to carefully match your protection device to the size of the spike you are willing to allow and the amount of energy that you need to dump from your coil. If at all possible, you should also isolate your coil driv- ers from more sensitive parts of your circuit. Optoisolators and individual power supplies are great for this. More info on spike protection and computer interfacing appears in my Micro Cookbook, volume II. Alternators as steppers? A stepper motor differs from an ordinary motor in that it can deliver incremental motion in the form of tiny precise steps, rather than as a contin- uous rotation. The important advan- tages of a stepper motor are the precision with which you can set an output shaft position, the ability to rapidly and conveniently change the direction or the speed of your output steps, and the capability of strongly holding a zero-speed position. Small stepping motors are widely used for such things as printer paper feeds, automobile idle controls, pen plotters, and sometimes for disk- drive head positioners. And most any old surplus electronics catalog will have lots of small steppers and all their drivers cheaply available. But what about the heavy stuff? There are lots of good hacking uses for power stepper motors. Ob- vious examples include robotics, ma- chine-tool power feeds, animation stands, plotters, sign cutters, solar pumps, and even Santa Glaus ma- chines. As you have probably noticed by now, power stepper motors are rare, horrendously expensive, hard to get, and harder to drive. Did I mention being hot and noisy? 68 An industrial arts teacher out of Phoenix by the name of Bob Knight stopped in the other day with what just might be a brilliant hack. Junkyard car alternators cost under $5 each, especially if you don't par- ticularly care which model you are getting. Can you convert an alter- nator into a power stepper? The needed modifications do ap- pear to be simple and obvious. And power FET or Darlington drivers are no big deal these days. My first response was "yes, but...," and I immediately came up with a dozen good reasons why this flat out would not work. At least not very well. Things like a wide air gap, low-frequency mechanical reso- nances. DC biasing, giant step sizes. all the non-optimum magnetic paths, very poor damping, backlash, slow speeds, and an efficiency that proba- bly would be an outright joke. On the other hand, if you pulse an alternator, there is no way you can hold onto it when you do. The kick is definitely there. At best, I would guess that you could not get as much useful force with a car alternator as you could by using a much smaller "real" stepper motor. And the alternator would end up ridiculously slower to boot. I'd like you to try and prove me wrong. Either as this month's contest or for a winning school lab project, experiment with a car alternator and find out exactly how useful a power stepper motor you could convert it into. Could you in fact create a $5 machine-tool power feed with one? How fast can you go? How much out- put force can you get? How good are the steps? What is the best computer interface? There will be the dozen or so of our usual Incredible Secret Money Ma- chine book prizes, along with a big all- expense-paid (FOB Thatcher, AZ) tinaja quest for two going to the very best of all. Okay, Fig. 4 shows you some con- version hints. Most real stepper motors do use a permanent magnet rotor. With an al- ternator, you would use the field winding and slip rings as a giant elec- tromagnet, running as much current through it as you can without over- heating. This forms a group of seven shaft-attached magnets that you can rotate to a desired position by activat- ing the stator coils. +12 voc o STATOR A MODIFIED CAR ALTERNATOR ^ STATOR 6 STATOR C ROTOR 1_ 5O..10W 5 5O.10W 5D,10W 3Ii.10W Silicon power transistors, Power Darlingtons, or Power FETs FIG. 4 — CAN A CAR ALTERNATOR get converted into a S5 power stepper for a machine tool drive? Only hackers know for sure. To experiment, use the rotor as a powerec electromagnet. Find the floating stator wye connection and bring it out as a power terminal. Pulse one stator winding at a time in an ABC (clockwise) or an ACB (coun- terclockwise) sequence. Be sure to limit stator currents. And speaking of which, there are normally three sets of stator coils. These are usually hooked up in what is known as a three-phase wye cir- cuit. For stepper use, you will want to find the floating splice where your wye connection is made and bring it out as a separate positive terminal. Which should then give you three dis- tinct and independent winding sets. Let's call the windings A, B, and C, Power the field via the slip rings, and pulse winding A. Keep your current down around an amp or two at first to BAKERIZING With BAKERIZING, your toner image is temporarily placed in close contact with a smooth film. Heat and pressure is then applied. The toner becomes much blacker and takes on a beautiful medium to high gloss. Some films can be reused. LAMINATING With LAMINATING, a thin clear plastic overlay is permanently attached to your copy by using heat and pressure. This process seems ideal for menus and book covers, or where extreme scuff resistance to "lock in" your toner is required. u FIG. 5 — THESE TWO "MAGIC" FILMS can dramatically improve the appearance and durability of any toner image. Evaluation sheets are newly available. w m | m rr x ID as 69 prevent any overheating or driver problems. The rotor will align itself with the nearest pole piece and should lock itself to some position. Now turn off winding A and activate winding B. The rotor should nowjump one step clockwise. Turn off B and whap C. And you should jump yet another step clockwise. To step clockwise, use an ABC se- quence. To step counterclockwise, just use ACB instead. You'll probably want to keep at least one winding energized at all times so that you can hold a position when not stepping. Note that you could end up in posi- tion A, B, or C. depending on your power sequence. You'll have to re- member where you are with your con- troller or host computer, A typical alternatorshouldgiveyou21 possible positions, and a resultant step angle of around 17 degrees. You would disconnect all of the al- ternator diodes during your con- version. These could later get used as protection diodes with your driver circuits if you do not have anything better available. One hint: Your slip ring brushes can "explode" whenever you take an alternator apart. And the two brush springs will fly off into the hinterlands. Look closely, and you'll fipd a tooth- pick-size hole in the insulated brush holders. To reassemble, you just put a toothpick or a stiff wire through the hole to hold the brush springs com- pressed. Done just right, you should be able to remove the toothpick from the outside after your reassembly. The rotor winding of an alternator is a fairly high resistance, usually around 5 ohms or so. It will safely current limit itself. But your stator windings are an extremely low imped- ance, typically under a quarter ohm. Thus, you must externally limit your rotor currents to keep things from burning up. Plain old power resistors are a good way to handle this for your early experiments. There are some tricks you could pull to improve the number of steps per revolution. One would be to allow two windings to be active at once. That could double your resolution. A fancier technique would be to allow several different values of the current for each winding, leading to various new microstepping oppor- tunities. Microstepping is a proven concept with real stepper motors. Another possibility is to use a Active Electronics 11 Cummtngs Pk Woburn MA 01801 (800) 677-8899 CIRCLE 301 ON FREE INFORMATION CARD NAMES AND NUMBERS Photocomm, Inc 7681 East Gray Road Scottsdale, AZ 85260 (800) 223-9580 CIRCLE 309 ON FREE INFORMATION CARD Alrpax 150 Knotter Drive Cheshire, CT 06410 (203) 271-6000 CIRCLE 302 ON FREE INFORMATION CARD DC Electronics PO Box 3203 Scottsdale, AZ 85271 (800) 423-0070 CIRCLE 303 ON FREE INFORMATION CARD Galco 26010 Pinehurst Dr Madison Heights Ml 48071 (313) 542-9090 CIRCLE 304 ON FREE INFORMATION CARD Hello Direct 140 Great Oaks Blvd San Jose, CA 95119 (800) 444-3556 CIRCLE 305 ON FREE INFORMATION CARD Maxim 120 San Gabriel Drive Sunnyvale, CA 94086 (408) 737-7600 CIRCLE 306 ON FREE INFORMATION CARD Memory Card Systems & Design 6300 S Syracuse Way, Ste 650 Engiewood, CO 80111 (303) 220-0600 CIRCLE 307 ON FREE INFORMATION CARD Motorola 5005 East McDowell Road Phoenix, AZ 85008 (800) 521-6274 CIRCLE 306 ON FREE INFORMATION CARD bridge-type drive that lets you run cur- rent either way through any given winding. You could now use both at- traction and repulsion, and, once again, should be able to double the number of steps. And a final resolution enhancer would be to put a nutplate of some sort on the shaft end. creating a linear stepper. A threaded shaft through the nutplate will then move forward or backward as the alternator steps. For instance, with a '/4-20 thread, each full revolution would advance you fifty mils. One single step at 21 steps per revolution would advance you a mere 2.38 mils, besides giving you a really major mechanical advan- tage to boot. Simple gearing could also be used Rochester Electronics 10 Malcolm Hoyt Drive Newburyport, MA 01950 (508) 462-9332 CIRCLE 310 ON FREE INFORMATION CARD SGS-Thomson 100 East Bell Road Phoenix, AZ 85022 (602) 867-6259 CIRCLE 311 ON FREE INFORMATION CARD Slo-Syn 383 Middle Street Bristol, CT 06010 (203) 582-9561 CIRCLE 312 ON FREE INFORMATION CARD Sp rag ue 70 Pembroke Road Concord, NH 03301 (603) 224-1961 CIRCLE 313 ON FREE INFORMATION CARD Synergetics Box 809-RE Thatcher, AZ 85552 (602) 428-4073 CIRCLE 314 ON FREE INFORMATION CARD Trade winners PO Box 7-250 Taipei, Taiwan, ROC (02) 733-3988 CIRCLE 31S ON FREE INFORMATION CARD JC Whitney 1917-19 Archer Avenue Chicago, IL 60680 (312) 431-6102 CIRCLE 316 ON FREE INFORMATION CARD to increase your step resolution. But you will have to watch for backlash when you try this. And do note that the finer the resolution, the slower your maximum allowable operating speed. Sorry about that. You might also like to look at some dual current scheme that gives you a brief high-current pulse when step- ping and some lower holding current between the actual steps. After you do have your stepper working reasonably well, you'll want to increase the operating currents. Overheating, saturation effects, and overshoots set your ultimate limit. It might also be very interesting to rewind all the stator coils. Use lots more turns of a much smaller-diame- ter wire, and try bridging only a single 70 PROGRAMMABLE LOGIC RESOURCES Actel Mitsubishi 955 East Arques Avenue 1050 East Arques Avenue Sunnyvale, CA 94086 Sunnyvale, CA 94086 (800) 227-1817, ext. 60 {408) 730-5900, ext. 2106 CIRCLE 317 ON FREE INFORMATION CARD CIRCLE 327 ON FREE INFORMATION CARD Altera 2610 Orchard Parkway San Jose, CA 95134 (800) 800-EPLD CIRCLE 318 ON FREE INFORMATION CARD Advanced Micro Devices PO Box 3453 Sunnyvale, CA 94088 (800) 222-9323 CIRCLE 319 ON FREE INFORMATION CARD Catalyst 2231 Calle de Luna Santa Clara, CA 95054 (408) 748-7700 CIRCLE 320 ON FREE INFORMATION CARD Cypress Semiconductor 3901 North First Street San Jose, CA 95134 (800) 952-6300 Dept. C4P CIRCLE 321 ON FREE INFORMATION CARD Fujitsu 3545 North First Street San Jose, CA 95134 (800) 642-7616 CIRCLE 322 ON FREE INFORMATION CARD Gould AMI Semiconductor 2300 Buckskin Road Pocatello, ID 83201 (208) 234-6668 CIRCLE 323 ON FREE INFORMATION CARD International CMOS Technology 2125 lundy Avenue San Jose, CA 95134 (408) 434-0678 CIRCLE 324 ON FREE INFORMATION CARD Intel 1000 Business Center Drive Mt. Prospect, IL 60056 (800) 548-4725 CIRCLE 325 ON FREE INFORMATION CARD Lattice Semiconductor 5555 NE Moore Court Hillsboro, OR 97124 (800) FAST-GAL CIRCLE 326 ON FREE INFORMATION CARD stator pole rather than three. Ampere turns is the name of the game here. You could also try improving the rotor flux paths and air gaps. For further resources on power stepping in general, check out Airpax and Sio-Syn for iron, the POM and Motion trade journals for info, and SCS, Sprague, or else Motorola for drivers. One distributor that stocks a National Semiconductor 2900 Semiconductor Drive Santa Clara, CA 95051 (800) 272-9959, ext. 40 CIRCLE 328 ON FREE INFORMATION CARD NEC Corporation 401 Ellis Street Mountain View, CA 94039 (415)965-6000, ext. 6357 CIRCLE 329 ON FREE INFORMATION CARD GEC Plessey Semiconductor 13900 Alton Parkway, S 123 Irvine, CA 92718 (800) 927-2772 CIRCLE 330 ON FREE INFORMATION CARD Raytheon 350 Ellis Street Mountain View, CA 94039 (415) 962-7930 CIRCLE 331 ON FREE INFORMATION CARD Texas Instruments PO Box 117692 Carroliton, TX 75011 (800) 336-5236. ext. 3707 CIRCLE 332 ON FREE INFORMATION CARD Toshiba 1220 Midas way Sunnyvale, CA 94086 (800) 321-1718 CIRCLE 333 ON FREE INFORMATION CARD Waferscale Integration 47280 Kato Road Fremont, CA 94538 (415) 656-5400 CIRCLE 334 ON FREE INFORMATION CARD Xicor 1511 Buckeye Drive Milpitas, CA 95035 (408) 432-8888 CIRCLE 335 ON FREE INFORMATION CARD Xilinx 2100 Logic Drive San Jose, CA 95124 (408) 879-5199 CIRCLE 336 ON FREE INFORMATION CARD wide selection of power-electronics stuff is Galco. And good old J.C. Whitney has bunches of alternators and parts available, including some rewound 100-amp stators that go for around $18. You will find lots more on power electronics in our brand new Hardware Hacker ill reprints. There's lots of possibilities here. Let's see what you can come up with. Programmable logic Besides all those good old hacker EPROM's, we now have dozens of variations on low-cost you-program integrated circuits. Some (such as EPROM's) are based on exhaustive table lookups. While others (such as PLA's) do multilevel and on digital log- ic using combinations of gates and registers. Some are one-shot programmed by blowing fuses. Others are easily re-programmable. And yet others use a flash technology where the needed connections can get saved to a non- volatile RAM memory during power- down times. The prices of some programmable chips are now down in the $2 range. Important advantages of these new devices are that you can place the exact circuit you want into one or two packages; that they are easy to de- bug and modify yourself; that some can recalibrate or update themselves later on in-circuit; and that you are (at least temporarily) the sole source of your "secret" inside programming connections. All with instant delivery and no staggering setup charges. I've tried to gather together some of the more popular programmable logic suppliers into this month's re- source sidebar. You may want to get data from many of these sources. One side note that is both alarming and sad: Many of these houses re- fuse to divulge the key programming info needed to use their chips. While I consider this a monumentally stupid way to cut off your nose to spite your face, their argument is that they most definitely do want you to use some "approved" programmer that is more likely to keep their products reliable in the final circuit. Here's a trick that may help you get programming info should reasonable and direct tries fail. The magic new buzzword in chip programmers these days is "DAC per pin." Just tell those application engineering people that you are about to ship production quantities of your new PC-based DAC-per-pin programmer, and that you would like to be able to include pro-grammability for their chips. Our helpline has been full of horror stories on programming info, but this ploy seems to work so far. At least till they catch on. Please do continue to send in your horrors stories. More details on the use of EPROM's appears in my CMOS GO m -0 - m to to 71 m O 2 o CC I,EARI\ VCR REPAIR TECHNIQUES Now, in a complete multimedia package consisting of a 200- page training manual and a 1-hour 22-minute video training tape, you can leam secrets of Advanced VCR Repair. (Also includes Color Bar Test Tape.) Indudesmany exam pies of VC R make/model specific troubleshooting tips . . . Learn how to quickly isolate most "tough" VCR malfunc- tions, whether electrical or mechanical. Complete coverage of Theory of Operation — Read manual, view 1-hour 22-minute video I FREE INFORMATION PACKAGEl Call 1/800-537-0539 Viejo Publications, Inc. 5329 Fountain Ave., Dept. REA Los Angeles, CA 90029 CIRCLE 179 ON FREE INFORMATION CARD Shortwave Listening Guidebook by Harry Helms The world is talking on shortwave radio, and here's the book that tells you how to listen in! In direct, nontechnical language, Harry explains how to get the most from your shortwave radio. Its 320 heavily illustrated pages are filled with practical advice on: • antennas • when and where to tune • selecting the right radio for you • accessories • reception techniques Leam how to hear the BBC. Radio Moscow, ham radio operators, ships at sea, even Air Force One! Includes hundreds of frequencies for stations around the world and the times you can hear them. frj Only $16.95 plus LU 6 D < tr 72 vniy$10.H2pius T y 1 r~w-t $3. 00 shipping J^ I CrJlIeX t (CA residents D p a b 1 1 nn I ku . i ne. (CA please include sales tax). ' Pub 7128 Miramor Rood Suite 15L. San DioG.il, CA 82121 Cookbook and TTL Cookbook, while the listings in our resource sidebar and the usual trade journals will also have lots of application info. Bakerizing secrets Despite my screaming it from the rooftops for quite a fow yea re now, Bakerizing seems to remain a top- secret procedure. Which amazes me because anyone that sees what the process does is absolutely stunned. Bakerizing is a sneaky trick you can apply to most any toner image, es- pecially all your PostScript laser- printed output. Bakerizing instantly makes toner a high-gloss jet black, while at the same time dramatically increasing the durability and crease- resistance. While excellent for business cards, Bakerizing works nearly anywhere that you want a blacker and denser toner image. And the process is near- ly free! All you have to do to Bakerize is take a sheet of special high-gloss, slip-coated polyester film. You then temporarily place the film in contact with your toner image and then apply heat and pressure. This remelts your toner in contact with an ultra-smooth surface. Which then can produce a catandering process similar to that ferrotype drum on older darkroom glossy print processors. The simplest way to Bakerize is to put the magic sheet on top of your hard copy and shove it back through your printer while imaging a blank page. The best way to Bakerize is to use a Kroy Color or Canon fuser unit or some sort of laminating machine. But even a plain old iron can some- times be used effectively. With care, any single Bakerizing sheet can be reused dozens of times. Which can drop your per-page costs to a few pennies per copy. I have gone ahead and custom or- dered a zillion sheets of Bakerizing film and will be offering it as a stock product here at Synergetics, I've also now got some more traditional yet toner-compatible laminating materi- als suitable for nice looking menus and book covers. Figure 5 shows you how these two films differ. Give me a call if you want to play with either of these really exciting new materials. New tech lit From SGS, the new Shortform 91 catalog that is especially strong in automotive, telephone, VCR, and consumer audio chips. From Rochester Electronics, a 1991 Cata- log. They specialize in stocking many types of out-of-date and discontinued semiconductors. A free design guide and catalog on Solar Electric Power Systems from Photocomm inc. is now available. And the latest free volume of the Maxim Engineering Journal has all sorts of goodies in it on efficient reg- ulators, digital filters, and other inno- vative new chips. Two informative trade journals for this month do include Memory Card Systems & Design on the new RAM and EPROM memory cards used for laptops and whatever: and Trade Win- ners. The latter journal is sort of a Hong Kong version of Computer Shopper that can give you direct ac- cess to many Far East manufacturers and distributors of electronic parts and systems. Let's see. I've just reprinted my Incredible Secret Money Machine. along with a new introduction and up- date section. And we are now Book- on-demand publishing our Hardware Hacker III, Ask the Guru lit, and also my Midnight Engineering I reprints. A reminder about my new BBS up as GEnie PSRT. Besides all of the PostScript and desktop publishing stuff, you'll find all sorts of ongoing Hardware Hacker and our Midnight Engineering resources here. You can get your voice connect info by dialing (800) 638-9636. Finally, I do have a pair of new and free mailers for you. One includes dozens of insider hardware hacking secret resources, while the other is on PostScript and Desktop Publish- ing, Write or call for info. As usual, most of the items mentioned here appear in the Names and Numbers or the Programmable Logic Resources sidebars. r-e Fve hetirtl you were iovkitix for me . . . Super amtluctvr? Computer Viruses jgf ! >c^kt' tfft 3382 P S2935 Counts as 2 INTEL'S OFFICIAL GUIDE TO 386 COMPUTING! H1G93-9P S29.9S 1 l/V» 9372P I21.9S Countt At 3 3951 P S18.9E — ^ - JjaSyMJatog'^ PM0UMUMC M BB . . 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( S5.95 Find out how to back up files, organize V Value; your disk for peak performance and more r- i The Computer Book Club Mi Its snE Soot CtulT Blua Ridge Summit, PA 17294H3B20 Please accept my membership in The Computer Book Club with the BYTE Book Club and send the 3 volumes listed below. billing me $4.95 plus my tree copy ot Hard Disk Management (#88148Q-4P^ If not satisfied, I may return the books within ten days without obligation and have my membership cancelled, \ agree to purchase at least 3 books at regular Club prices during the next 2 years and may resign any lime thereafter. A shipping/handling charge and sales tax will be added to all orders. 372Q 526.9:5 150S7P 535.05 Oeunls it a Name . Address City State _ _Zip. Valid tor new members only, Foreign applicants will receive special orris ring instructions Canada must remtt in U.S. currency. This order subject to acceptance by The Computer Book Club HP1C991 3379P £24.95 I--.- mblj Loftguas? SubroutlnB for MS-DOS 3679P 5112.95 Iriiru I HI** Guaranteed! 333tp 5H-95 9S49P S2«.9S Hie C Primer 382a S29.95 Counts as 2 ■mm UMMG Kisiun: sik*!«t HIUH ■ 1 1 £^- ^ ! ] 3SB3P SSt9S Ccurvtt M 3 m m SO CO 73 AUDIO UPDATE Future products? LARRY KLEIN Despite my thirty-plus years as an editor and writer for major hi-fi magazines, I've always been an odd-man out among audio journalists. When I saw a develop- ment that struck me as a genuine advance in the audio-video arts, I was pleased to say so. But unlike many, if not most, of my colleagues, I never felt an obligation to be a knee-jerk cheerleader for each new audio con- cept, device, or format. Hopefully, over the years my approach has helped readers find their way through the fast-changing and sometimes confusing world of audio electronics. In-store recording Sometimes new developments are hard to call. For example, loyal read- ers may remember my November 1988 writeup of the Personics in- store tape-it-yourself machine. It per- mits consumers to record their own top-40 — or whatever — compilations at perhaps a buck a shot from its thousands of digitally stored mas- ters. I was impressed by Personics very sophisticated technology, but I asked whether it might not be a tech- nically feasible idea that, neverthe- less, wouldn't get off the ground because it didn't dovetail with the per- ceived social or economic needs of the marketplace. My question was recently an- swered when Personics filed for Chapter 11 bankruptcy protection. It seems that although the record stores were pleased to install the ma- chines, the record companies wouldn't provide Personics with a sufficient number of their more popu- lar selections, despite the fact that they earned royalties on every selec- ts tion taped. They obviously felt that it z would hurt prerecorded cassette and § CD sales. It seemed to me that Per- o sonics had made a good case that j their machine would help cut back on i "illicit" home taping, but the record 5 companies obviously didn't see it S that way. Recordable CD's A product/format that I ignored when it was first introduced was Ra- dio Shack's home-recordable com- pact-disc system, dubbed "Thor" for Tandy High-Intensity Optical record- ing. Announced in June 1988, the Thor recorder/player was to be priced at under $500 and be on the market in less than two years. The press went wild! Laudatory articles appeared in major publications and at least one audio columnist predicted that it "could well become the domi- nant recording method for the next several decades." Well, here we are three years later, and the product is nowhere to be seen. A recent call to Radio Shack/Tandy revealed that Thor was still in the works; it had reached the "product development" stage, but Radio Shack thought it prudent not to re- schedule a release date. In our con- versation. I indicated that I saw the recordable high-density disc as suit- able for computers Ca sort of cheap recordable CD-ROM), but I didn't see much future for it as a hi-fi medi- um. My friend from Radio Shack told me that they were working in the op- posite direction. A year, or two, or three, from now we may know who was right. Mini discs Scheduled to appear sometime in late 1991, the Sony Mini Disc system uses 2.5-inch record/playback discs physically similar to 3.5-inch comput- er discs. The MD system uses a combination of optical and magnetic digital technology; prerecorded discs are optically read with a laser, and home recording is done using a so- phisticated thermal/magnetic sys- tem with the laser providing the thermal element. Guesttmated intro- ductory price is in the $350 range. The Mini Discs have a storage ca- pacity virtually identical to that of a conventional CD, thanks to Sony's newly developed digital compression system call ATRAC (Adaptive Trans- form Acoustic Coding). ATRAC works by analyzing the audio signal and extracting and encoding only those components that are audible to DOES SONY'S MINI DISC SYSTEM WITH RECORDABLE DISCS represent the audio format of the future? 74 the ear. In other words, frequencies that would be psychoacousticaJly masked by other frequencies are left unencoded as are frequencies on the loudness scale judged to be below the threshold of perception. Although the dynamic range of the MD system Is given as 105 dB, I wonder if play- back through an external home audio system will reveal any ATRAC inade- quacies. In any case. Sony's present plans are to concentrate on portable ap- plications which are far more forgiv- ing of compression artifacts. There are several other important tech- nological developments incorporated into the MD format that are important enough to deserve further discus- sion, but they are outside the scope of this column. Ss this Sony's answer to the DCC format discussed last month? Well, Mr. Norio Ohga, President of the Sony Corporation, stated in his pre- pared remarks at the Mini Disc press conference, that the "sales of pre- recorded music cassettes are declin- ing, especially in Japan. We have investigated the reasons for this de- cline, and our own research showed that consumers are not totally satis- fied with music compact cassettes, primarily because of slow access time and such problems as wow, flut- ter, and distortion." I suspect that the fall-off in pre- recorded cassette sales has more to do with the success of CD than newly bothersome flaws in the cassette for- mat. When the earlier choice was be- tween an LP or a prerecorded cassette, the cassette won on the basis of convenience and rugged- ness. Now that the choice is between CD's and cassettes, the CD has the edge in convenience and rugged- ness — and you can always make your own cassette copy to take with you in your travels. I also differ with Mr. Ohga on the importance of the fidelity factor for the U.S. mass music market. If fidelity was that important to most rock music consumers, prerecorded cassettes would never have outsold LP's — as they did for several years before CD's arrived. Is the market- place ready for another non-compati- ble portable/car format? I wish Sony well, and I'm impressed by the tech- nology developed for the Mini Disc, but I'm not optimistic about its ulti- mate success in the marketplace. HDTV Billed as high fidelity for the eyes, high-definition television is a favorite topic among Sunday supplement magazine writers. Soon, they would have us believe, our 30- or 40-inch home TV screens will be showing pic- tures that, in respect to aspect ratio, clarity, and detail, will rival those seen in movie houses. Well, don't hold your breath — or put off purchasing a TV set with today's old fashioned technology. HDTV is not just around the corner. HDTV's major problems are not technological — they are economic and sociological. To start, the broad- casters must transmit separate HDTV and standard signals simulta- neously in order to comply with the FCC's compatibility rule. If they want to originate programs, they need new cameras, recorders, control-room boards, and dedicated transmitter. Then there's the antenna problem. In many instances, an additional tow- er will have to be put up for HDTV. And we shouldn't forget the problem of the required extra channel space, which just isn't available in all market areas. Direct-broadcast satellite will short circuit some of the above prob- lems, but only at the expense of the local broadcasters who would protest its adoption. Given all of the above, I suspect that the FCC will start seriously con- sidering authorizing the use of one of the "enhancing" systems that pro- vides a better and wide-screen pic- ture from the current NTSC system. For the broadcasters, the equipment required to encode additional infor- mation into their present transmis- sion systems should be relatively inexpensive as such things go. For the consumer, however, I suspect that the price of an enhanced TV sys- tem will move it out of the casual purchase category. Which brings me back to the same old question — is there a large enough audience for HDTV Cor enhanced TV) to make it a commercially viable en- terprise? The fact that you can get a much better picture from a videodisc than a video tape hasn't had much positive impact on videodisc sales. 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New features The most important feature of DOS 5.0 is the ability to load part of itself into the High Memory Area (HMA). the first 64K of memory above the 1MB mark. (Normally memory above 1MB is unavailable to DOS programs, but due to a quirk in the Intel addressing scheme, real- mode DOS programs can get at the first 64K of extended memory with- out switching the microprocessor into protected mode. Although use of the HMA has been understood for several years, Digital Research's DR- DOS, released about a year ago, was the first and, until recently, the only operating-system product to use it. The HMA is only available on 286 and higher machines with extended mem- ory.) By loading DOS in the HMA. you can boot your machine with much more memory than before. For exam- ple, I now boot with about 625K of free memory. DOS 5.0 also includes a 386/486 memory manager that can map RAM into upper memory blocks CUMB), unused address space in the area be- tween 640K and 1MB. You can then install device drivers and TSR's in that area. For example, I load device driv- ers for a disk cache and a RAM disk, a special video driver for a Hercules Graphics Station Card, several key- board-related TSR's, a mouse dnver, and LANtastic networking soft- wans — and still have about 625K of free conventional memory. That's a nice feeling. But does it work? It sure does. Microsoft wanted to avoid the kind of controversy that sur- rounded the release of DOS 4,0, so the company went through extensive qualification procedures (including some 7000 beta testers). And it shows, I've got a fairly complex set- up, including a SCSI-based hard disk, the 34010-based Hercules card, tape backup unit, and networking interface card. Installation was smooth and documentation clear; it all worked the first time, without a hitch. Goodies DOS 5,0 includes lots of neat little goodies, including built-in help mes- sages for most commands, that may take the wind out of utility vendors' sales. (Some of those utilities were in fact licensed from those vendors, who have already announced en- hanced versions.) Following are se- lected highlights of some of the updated commands. The Del command accepts /p to prompt you to confirm file deletion. The Devicehigh command loads de- vice drivers into UMB's. The Dir com- mand will sort files in forward or reverse order by name, extension, date/time, and size: you can also dis- play by attribute (hidden, system, read-only, archive); you can include subdirectories; there are other op- tions as well; and you can set up an environment variable (DIRCMD) that specifies your favorite format. Doskey provides a command-line editor/macro/history facility like CED and DOSEDIT. The Format command has a "quick" option (/q) that empties the file allocation table (FAT) and root di- rectory of a floppy disk, but does not erase the data area (or scan for bad sectors). The Graphics command, though slow, at long last supports all stan- dard video modes and numerous printers, including LaserJets. MS-DOS Shell File Options Uieu Inta Help C:M.ftNTAST[ SJfl [^)B lm*S L3D L3E IZ3F C3N EDO £n]? S9 E23R ES)S Directory Tree I-Cj DOS -£j E2WE SSEMU — £d bulletin ■f£l LANTASTI .NET °~\ LOTUS LU MAG2 ■ r~l NORTON j-Pj 0LD_D0S.l Q PC INDEX Pn pcflus i pro SElfi EsDH QC LZJD CUE LZ1F i~°in cdo E3P [EflE S3R S3S Birectorij Tree 00 ARCS D MT CD BKSHLF | CZPC ■O C0MPTQNS -0j DISC PASS -ri dos -rj ee -00 FAX -P~| INFO lug esjh cri C3J E3T C2K cz)L r^i N C:\LflNTflSTIv**, E3 A1LANB10.EXE El CONFIG .SVS F3 IMS TALL .EXE m I MS TALI. .FLS 13 INSTALL .HLP E3 I.ANCACHE.EXE H LANCKECK.EXE Eh LANCHECK.HLP B LANPUP .EXE F3 HET .EXE E NET .HLP CZ]G (H3H C31 CM EST AUTOEXEC. BAG E) AUTOEXEC. BAK E3 AUTOEXEC.BAT El AUTOEXEC. LAN fSh AUTOEXEC. MOW E A0AL0N .TXT ESJ BBftSH .BAK E BRASH .TXT H CUE .BAT E3 COMMAND .COM B CONFIG .BAC B,Z5B 89-13-98|n 13, 26? 09-14-38 123 10- IB -98 62,845 85-29-98 1,168 BS-2S-3B 8,174 85-25-30 | ■3,971 BS-31-9B I 13,181 05-03-90 I 4,937 85-21-90 I S,509 05-22-98 I 12,853 05-25-90 ■ 46,872 85-31-98 ffl FlB=flct jotis Sfcif t>F9=Cp«fiand Pyonpt C3K CZJL LZ1H 154 B9-29-9B|n 82-25-91 8225-91 I 1B-11-98 11-05-98 11-B8-90 B4-3B-91 84-38-91 10-18-98 B7-24-87 B9-29-9B 1 4 11:34a FIG. 1— MS-DOS 5.0 combines users' most- requested features in a comprehensive pack- age that frees 45K of conventional memory on 266 and 366 machines, has built-in undelete and unformat utilities, and a file manager/task swapper. This is the DOS you've been watting for. 76 RE Engineering Admart Rates: Ads are WyIW. One insertion $995 each. Six insertions $950 each. Twelve insertions $925 each. Closing date same as regular rate card. Send order with remittance to Engineering Admart, Radio-Electronics Magazine, 500-B Bi-County Blvd., Farmingdale, NY 11735. Direct telephone inquiries to Arline Fishman, area code-1-516-293-3000, FAX 1-516-293-3115. Only WO% Engineering ads are accepted for litis Admart. HIOI MIDI PROJECTS BP182 — MIDI interfacing enables any so equipped instruments, regardless of the manufacturer, to be easily connected to- gether and used as a system with easy com- puter control of these music systems. Combine a computer and some MIDI instru- ments and you can have what is virtually a programmable orchestra. To get your copy send $6.95 plus $1.25 for shipping in the U.S. to Electronic Technology Today Inc., P.O. Box 240, Massapequa Park, NY 11762-0240. LINEAR IC EQUIVALENTS & PIN CONNECTIONS Linear IC Equivalents and Pin Connections BP141 — Shows equivalents & pin con- nections of a popular user-oriented selection of European, American and Japanese liner IC.'s 320 pages, 8 x 10 inches. $12.50 Plus $2.75 shipping. ELECTRONIC TECHNOLOGY TODAY INC., PO Box 240, Massapequa Park, New York 11762-0240. FCC LICENSE PREPARATION The FCC has revised and updated the commercial license exam. The NEW EXAM covers updated marine and aviation rules and regulations, transistor and digital circuitry. THE GENERAL RADIOTELEPHONE OPERATOR LICENSE - STUDY GUIDE contains vital information. VIDEO SEMINAR KITS ARE NOW AVAILABLE. WPT PUBLICATIONS 979 Young Street, Suite E Woodburn, Oregon 97071 Phone (503)981-5159 Depf. 50 CIRCLE 184 ON FREE INFORMATION CARD Loadhi lets you load TSR's into the UMB area on 386 and higher CPU's. Mem displays information about the amount of free memory and loaded programs. The Mirror command backs up im- portant information about your hard disk. Mirror also optionally installs a TSR that keeps track of deleted files. Undelete and Unformat use that in- formation to help in case of disaster. Mode now lets you specify 43- and 50-ltne VGA video modes, and key- board repeat and delay rates; it also supports COM3 and COM4 at rates as high as 19,200 bps. QBasie. which supersedes GWBASIC. is based on Microsoft's QuickBASIC environment. QBasie includes a hypertext help system but no printed documentation; programs can be saved in ASCII format to disk but cannot be compiled without the full QB environment. DOS 5.0 also includes a full-screen editor; the edi- tor is the QBasie environment. (For comparison, invoke EDIT.COM then QBASIC /EDITOR.) And yes. Edlin is still included. Ren (rename) still has not been up- graded; I guess I'll continue to use my 800-byte 1985-vintage utility to re- name subdirectories. Nor is there a Move command, although you can use the DOS Shell to move files. Tree displays a graphical view of your directory structure, but is quite slow. I've got a 500- byte 1985-era PD utility that works ten times faster. Undelete and Unformat may cause trouble for the Norton Utilities. Sys will make a disk bootable whether it is empty or not. In addition to ANSI .SYS and DRIV- ER SYS, DOS 5.0 now includes de- vice drivers for setting up a RAM disk (RAMDRIVE.SYS) and a disk cache (SMARTDRVSYS); these drivers su- persede the ones included with Win- dows 3.0. Another device d river C386EMM.EXE) provides EMS mem- ory emulation on a 386 or higher CPU: it can also optionally map RAM into the UMB area. To avoid conflicts with various hardware adapters. 386EMM. EXE includes options for in- cluding and excluding particular ad- dress ranges, and other options for specifying the address of the EMS page frame, and the number of task- switching handles and register sets. Installation is clean and easy; if you're upgrading from a previous ver- sion of DOS, the process saves your old DOS version in a separate sub- directory, and even forces you to create a bootable backup floppy in case something goes wrong. DOS is DOS, not Windows or OS/2 DOS 5.0 includes a file manager called DOSSHELL that allows you to perform standard file manipulation (copy, move, rename, run, view), that can serve as a launching pad for your applications, and that can even switch among several DOS pro- grams. It does not however perform multitasking in the manner of DE- SQview or OmniView (to say nothing of Windows or OS/2). So you can't download files from your favorite BBS while simultaneously working in your word processor; you'd have to use Windows, OS/2, or a competing package for that. Conclusions Microsoft has really done its home- work on DOS 5.0. On one hand, it has users' most requested features: It returns a big 45K chunk of RAM to the user, obviates the need for more than half a dozen utilities (DOS shell, keyboard enhancer, 386 memory manager, disk cache, RAM disk, un- delete and unformat utilities), and al- lows large disk partitions (2 GB). You can get more powerful versions of these utilities from other vendors. But you may not need to — or want to. DOS 5.0 has some glaring deficien- cies, but most of the new additions are worthwhile. In short, it works. Bugs may turn up in the future, but DOS 5 has already shown itself more reliable, not to mention useful, than its predecessor. On the other hand, with the re- sources Microsoft has at its disposal, surely it could have included a DE- m SQviewtype of multitasker. Why not? % DOS 5.0 is careful not to infringe on jjj the multitasking turf staked out for =i Windows (and OS/2). 55 m m 77 DIGITAL VIDEO STABILIZER ELIMINATES ALL VIDEO COPY PROTECTIONS While watching rente.) movies, you wilt notice an- noying periodic color darkening, color shift, ur> wanlod linns, Hashing or lagged edges. This is caused by the copy protec- tion jamming signals em- bedded In the video 'ape, such as Macrovislon copy protection. Digital Video Stabilizer: RXH compJelely ellmtnales all copy prelec- tions and }amming signals and brings you crystal clear pictures. FEATURES: • Easy to use and a snap to Install •Slaie-of-the-art in- tegrated circuit lechnol- • 1 56% automatic - no need for any troublesome adjust- mants • Compatible to all types ofVCRsandTVa #The best and most axctt- ing Video Stabilizer In the market • Ught weight (3 ounces) and Compact (1x3.5k5 ) • Beau! J u. deluxe gift box • Uses a standard 9 Volt battery which wilt last 1 - £yearv WARNING : SCO Electronics and RXII dealers do not encourage people to use the Digital Video Stabilizer to duplicate rental movies or copyrighted video tapes. RXII is in- tended to stabi- lize and restore crystal clear picture quality for private home use only. ( Dealers Welcome ) ToOrder:SS9.95ea 1-800-445-9285 Visa, WC, COD M-F:9-6 SCO ELECTRONICS INC, Dapt CRE9 S81 W. Merrick Rd. Valley Stream NY 11580 Unconditional 30 days Money Back Guarantee S4 lor FAST UPS SHIPPING or 516-568-9850 {baltery not included) CIRCLE 187 ON FREE INFORMATION CARD CABLETV DESGR AMBLER How You Can Save Money on Cable Rental Fees H o 1 Unit 5+ JcrroldSBwrTri-BI. $99 $70 _„ .„ ..... ,„ SuptrTri-Bi (TBM }. 1 1 W....S75 US Cable will Jsrrold 450combo $189 ...$13o Beat Anyone's Scientific Atlanta $ 109....S75 p j Ji SA 8534™ $2S0....S19S ■ rrlce , Pioneer. $ 109...S79 Advertised In Oat KN 12 (w/VS) .$!<» ...$S5 (his Magazine ! Hamlin MLD 1200, m. $59 ^ Totem. „.._._ J169....S129 Stirgate converter __ $89™I*9 Panasonic TZPC145 $99 $19 30 Days Money Back Guarantee Free 16 page Catalog Visa, M/C, COD or send money order to; US Cable TV Inc. De P t. kreq 4100 N.Powerline Rd, Bldg F-4 Pompano Beach, FL 33073 1-800-772-6244 o rr LU _l LU 6 Q < rr For Out Record [. the undersigned, do hereby declare under penalty of per- jury that all products purchased, now and in the future, will only be used on Cable TV systems wi th proper authorization from local officials or cable company officials in accordance with all applicable federal and state laws. FEDERAL AND VARIOUS STATE LAWS PROVIDE FOR SUBSTANTIAL CRIMINAL AND CIVIL PENALTIES FOR UNAUTHORIZED USE. Date: Signed r 78 No Florida Sates! The question now is: What next? There is talk that the next version of DOS will include built-in networking, an installable file system, multiple concurrent DOS sessions, clean ac- cess to extended memory... that sort of thing. Congratulations, Microsoft. When will we get a version of OS/2 that works as well? News bits IBM/Microsoft sparring con- tinues: IBM has been going to great lengths recently to demonstrate its independence from Microsoft. First, as reported last time, IBM has team- ed up with Micrografx to build a better graphics engine for OS/2. Since then the company has shown Digital Re- search's DR-DOS running under OS/2 2.0; both DR and IBM are com- mitted to full compatibility In addition. IBM has teamed up with Borland, whose C 4- + program- ming environment will be released for OS/2 2.0 by the end of the year. IBM is also developing its own 32-bit pro- gramming kit for OS/2. The company has publicly shown an early version of the OS/2 Presentation Manager (PM) that looks more like the Macin- tosh Finder than Windows; there are rumors circulating around that IBM is even looking into the possibility of licensing the Macintosh OS. Micro- soft, on the other hand, is busy at work developing a set of tools for porting OS/2 code to the Windows environment. Windows vs. OS/2 is becoming a religious issue in the trade press. Re- cent articles contain phrases like "pounded another stake through the heart of Presentation Manager," "Why OS/2 is dead." and so on. Sure, IBM doesn't want to become dependent on Microsoft. But both companies are developing products called OS/2, advanced versions of Windows and OS/2 have remarkably similar specifications, each company is licensed to the other's product, and both companies realize the devastat- ing effects of proprietary systems. We may end up with two different products — but there will be a high de- gree of compatibility between them. Multimedia mania. A high- ranking IBM official banged the drum for multimedia at Comdex once again, rattling off several challenges the industry must meet before main- stream multimedia becomes a reality, including standard data formats and API's (among IBM, Apple, Microsoft, and Commodore), a breakthrough in optical storage, reasonably priced full-motion video, compelling soft- ware, and extreme ease of use. On the equipment front, numerous companies are announcing expan- sion cards that provide digital audio capabilities for the PC: Covox (Sound Master) Brown-Waugh (Sound Blaster), Ad Lib Sound (Ad Lib), Me- diaVision (Pro Audio Spectrum), Tur- tle Beach Systems (MultiSound). These cards typically include MIDI compatibility, music synthesis, 44- kHz audio digitizing/playback, multi- source mixing. CD-ROM interface, microphone inputs, 12-bit A/D and D/A, audio amplifiers, etc. Prices range from $200 to $1000. Microsoft's multimedia strategy is about to blossom. In early summer, the company will release multimedia extensions to Windows. A multi- media version of Windows will be re- leased on CD-ROM, which will include all documentation in a hyper- text help facility, and will also include new accessory programs for access- ing multimedia data. The company is also scheduled to release a Multi- media Development Kit (MDK) dur- ing the summer. Friendly Windows develop- ment tools are sprouting up all over the place. Borland released a form- based package called ObjectVision several months ago, and more re- cently Turbo Pascal for Windows. Mi- crosoft returns to its roots with a release of BASIC called Visual BASIC. These products promise to revolutionize Windows product de- velopment efforts; watch for lots of powerful and fun new utilities and ap- plication programs. R-E "Clitttltvii, your fiuhi'y littx lwn rvpUnwt hy ti atrnptuer.' CIRCLE 188 ON FREE INFORMATION CARD NRI gives you two unbeatable opportunities for top pay, security, even a business of your own. Everybody wants to get ahead, but most people want assurance they're making the right job choice. According to the US. Department of Labor, jobs for electricians and air conditioning, heating and refrigera- tion technicians offer high earnings and good job prospects. Now MR] can show you how to go after the high earnings, the steady pay increases, even how to be your own boss in a business of your own. You'll get all the skills to get there. No night school, no need to quit your job until you're ready to make your move. NRI trains you right at home in your spare time. No Experience Needed. NRi starts you with the basics, then builds your knowledge and skill a step at a time, all the while adding practical know-how through hands-on training. You even get tools you need on the job or in a business of your own. Over a million and a half stu- dents have trained the NRI way since 1914. Be an Electrician. Each year, the demand for skilled construction, maintenance, commercial and utility electricians continues to grow. The U.S. Department of Labor estimates that close to 100,000 new jobs will open up in the next ten years -a conservative estimate compared to industry and union predictions. And few jobs can match the money-making potential of the qualified electrician. You can earn a salary in excess of $25,000 or be your own boss with your own electrical contracting business. Only NRI gives you this kind of practi- cal, job-oriented, hands-on training. You master practical skills like this with the equipment, test instruments, and training materials included in your course . . . you duplicate on-the-job wiring with your NRI Residential Wiling Practical Lab®. . . you learn professional troubleshooting using your Voit-Ohmmeter and Clamp-On Ammeter to test the circuits you build up on your NRI Circuit Demonstrator . . . and by installing and testing an electronic- programmable thermostat and a micro- processor-controlled remote power control, you come to understand today's electronics as it applies to the latest devices electricians install and repair. Training in the latest need-to-know electronics required of today's electrician. NRI created this new course so you can move from the simplest fundamentals of electricity, through professional wiring and trouble-shooting techniques, all the way up to mastering the practical field skills you need to become today's electronic-smart electrician. Be an electrician, it could be the best and last job choice you'll ever have to make. Be an Air Conditioning, Refrigeration, Heating Technician. When it comes to targeting the good paying jobs, regular pay increases, and the steady demand for your skills in this field, the U.S. Department of Labor scores a solid hit.. -high earnings and good job prospects attract many individuals... because people in business depend on their air conditioning, heating, and refrig- eration systems, the need for ski I led tech- nicians to do maintenance work has to be met regardless of swings in the economy. Add millions of window units in older homes requiring maintenance and repair; heat pumps so popular they're now as common as furnaces; commercial refrigeration alone calling for skilled tech- nicians to install and service walk-in cool- ers, freezers, ice makers, and food cases. Wherever you look, there's tremendous opportunities for the trained air conditioning, refrigeration, and heating technician. NRI training so complete, professional tools even included. NRI trains you lor this lucrative field, gets you ready to land a good paying job, pick up extra income in your spare time, even start a business of your own. You're ready to jump right in because NRI includes the tools you need: system analyzer, leak detector, tubbing and joint tools, a top- quality vacuum pump for purging systems, plus demonstration panel units for hands- on systems training. Graduates of our Master Course also get optional free residential training at the world-famous York Institute in York, PA. Go a f ter h igh earn i n gs , pay i ncreases , a business of your own. Send for NRI's free catalog. Find out what hands-on projects you do, the profes- sional tools you train with, and the future that can be yours. Act today. SEND COUPON TODAY FOR FREE NRI CATALOG' nor* „ '-^to,. MW^WM SCHOOLS McGraw-Hill Conlinuing Education Center 4401 Connectieul Avenue. NW. Washington. DC 20008 tk'if! tf ilnii , E , For Career courses approver) under CI Dill □ cnecit lor details CHECK ONE FREE CATALOG D Electrician G Air Conditioning Heating & Refrigeration □ Microcomputer Servicing D Small Engine Repair D Appliance Servicing D Lncksmithing ONLY C Automotive Servicing □ Bookkeeping & Accounting n Photography O TWAudioA/ideo Servicing □ Telecommunications 3 Desktop Publishing G Building Construction a Data Communications G Industrial Electronics □ Computer Programming C Electronic Design Technofogy c Cellular Telephone G Digital Electronic Servicing G Basic Electronics -Age. Street. Ci1y/Slale/Zip_ Accredited Member National HomeSludy Council 4218091 I m a m S 00 m 33 — I <£> to — L 81 ELECTROMAGNETIC THEORY continued from page 59 CO 9 z o CE H O UJ o Q < a: that are bound directly to the atom and cannot flow. If N is of magnitude 1 and is normal to the surface then o- b = P-N(C/ni2). Imagine a Gaussian surface in- side the dielectric. With a nonuniform charge distribution some of the bound charges will be displaced across the surface by P. leaving a net charge within the surface. In the same manner that we found V-E = pe , where p is the volume charge density of all the charges contributing to E, we can see that the volume charge density in the dielectric is V.p=- Pb (C/m 3 ). The negative sign means that the dipole moment per unit volume, P, points from negative to positive in the dipotes. It is customary and convenient to consider a field associated with just the free charge density p, since p b is due to the response of the material. That field must be due to the total charge density less the bound charge density, therefore Pf=p-pb = V-t E + V-P = VKE+P]. The term in brackets is called the displacement field vector D = e E + P(C/m2). In simple dielectrics, P and E are parallel, and the following re- lation holds true D = e (1 + K ) E = eE- e D can now be interpreted as the ability of empty space to support an electric field, and is called the permittivity of free space, e is the permittivity of the material. A commonly used quantity is the dielectric constant K = 1+x = e/t . K is greater than 1 for any materi- al, and goes to infinity for a con- ductor because E = in a conductor. K can be thought of as a measure of the modification of free space by the presence of a material. From our previous analysis, we have obtained one of Maxwell equations. Gauss' law which reads vD = Pl . Gauss' law says that the apparent spreading out of the displace- ment field vector D through a Gaussian surface is due to the density of free charges inside. Gauss' law doesn't say, however, that D is not producing a swirl. The static E contribution can't produce swirling, but the P con- tribution can. Capacitance We know that two conductors, separated by a dielectric with di- electric constant k, form a capac- itor. If one conductor has charge + q and the other - q, the mea- sure of the amount of charge that must be placed on a conductor to change its potential by one volt is called the capacitance, which is in units of coulombs per volt C = q/V (farads). If the free charge q increases, the displacement field vector D, which equals the e k field also increases. That causes a propor- tionate increase in voltage as E rises. Given a particular charge q, the only way to change the ca- pacitance is to change the volt- age. That can be done by changing the charge separation distances or by changing the properties of space to give dif- ferent E's. Simply filling the sepa- ration space with a material of greater dielectric constant re- duces the E field in that space, which reduces the voltage and in- creases the capacitance. We can use Gauss' law, without involved calculations, to deter- mine the change in the electric field when any capacitor is filled with a dielectric. In empty space, P = O and all the charges are free charges, therefore V.D/eo = V-E = P( /e , and YD/e = YxE = O. If the space is filled with a simple dielectric, D = e kE, therefore V-D/e = V-ftE= p|/«o. P is aligned with E so there is no apparent rotation and VxD/e = Vx/fE = O. The divergence and curl of E completely characterize the field. By comparison, the E for a charged capacitor with empty space as a dielectric is the same as kE for the same charged ca- pacitor with a dielectric constant k. In a capacitor filled with a di- electric, E is reduced by Ilk. The capacitance C = q/V is increased by k since the voltage potential V is reduced by 1/Jf. In our next edition, we'll look at the effects of electric charges in motion. We'll see that another type of field, the B field, is re- quired to describe the magnetic forces associated with them. R-E EQUIPMENT REPORT continued from page 18 frequency steps. A number of scanning functions are available: full memory scan, mem- ory block scan, and seek scan, (with two delay modes). The R8 can also be set to scan from the frequency of VFO A to VFO B. The two VFO's are available so that you can instantly switch and tune between two dif- ferent frequencies. The second VFO can be thought of as a sort of tempo- rary memory location. One of the nic- est features is that you can instantly transfer the frequency of the active VFO into the inactive one. So if you're tuning and come across an interesting signal — but not the one you're looking for — you can put it in- stantly in the inactive VFO as you continue your search. Returning to the interesting frequency is only two keystrokes away. A partial list of its built-in features include an RS-232-compatible inter- face that allows your computer to take complete control over all func- tions of the receiver. Two antenna connectors are provided. One is a coaxial SO-239 connector for 50- ohm antennas, the second is a spring-clip connector that can be used for 50- or 500-ohm antennas. The appropriate antenna can be se- lected from the front panel. An exter- nal-speaker jack and a headphone jack are provided, as are line-level au- dio connectors Cfor recorders or CW/RTTY demodulators! A mute connector lets the R8 be used in con- junction with a transmitter. We were impressed by the quality of the Drake R8. It is easy to use thanks in part to the clean layout of the controls, and to Drake's decision not to clutter up the front panel with a lot of unnecessary controls (which some manufacturers seem to think looks "hi tech"). We were even more impressed by the control the R8 gave us to hear the weaker signals we would have simply ignored on other world-band radios. If you're not familiar with world- band radio, don't even think of the R8. You simply won't appreciate what it can do for you. But if you're a short- wave enthusiast who is looking for something special and have about $1000 to invest, then we've found the receiver of your dreams. R-E 82 MARKET CENTER FOR SALE TURFS: "oktest." "latest.' Parts and schematics. SASE tor lists. STEINMETZ, 751 9 Maplewood Ave., RE, Hammond, IN 46324. HAVING trouble with IC's? We specialize in locating "hard to find" items! Low prices on eproms. micros, pals. Custom programmers built to your specs. CHAFFIN ELECTRONICS, (8I4) 974-4456 9AM to 5PM EST. CLASSIFIED AD ORDER FORM To run your own classified ad, put one word on each o( the lines below and send this (orm along with your check to: Radio-Electronics Classified Ads, 500-B Bi-County Boulevard, Farmingdale. NY 11735 PLEASE INDICATE in which category of classified advertising you wish your ad to appear. For special headings, there is a surcharge of $25.00. ( ) Plans/Kits ( ) Business Opportunities ( ) For Sale j | Education/ Instruction ( ) Wanted ( ) Satellite Television Special Category: $25.00 PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS. (No refunds or credits for typesetting errors can be made unless you clearly print or type your copy.) Rates indicated are for standard style classified ads only. See below for additional charges for special ads. Minimum: 15 words. 1 6 11 16 ($49.60) 21 ($65.10) 26 ($80,60) 2 7 12 17 ($52.70) 22 ($68.20) 27 ($83.70) 3 8 13 18 ($55.80) 23 ($71 .30) 28 ($86.80) 14 19 ($58.90) 24 ($74.40) 29 ($89.90) 5 10 15 ($46.50) 20 ($62.00) 25 ($77.50) 30 ($93,00) 31 ($96.10) 32 ($99-20) 33 ($102.30) 34 ($105.40) 35 ($108.50) We accept MasterCard and Visa for payment of orders. If you wish to use your credit card to pay for your ad fill in the following additional information (Sorry, no telephone orders can be accepted.): Card Number Expiration Date Please Print Name Signature IF YOU USE A BOX NUMBER YOU MUST INCLUDE YOUR PERMANENT ADDRESS AND PHONE NUMBER FOR OUR FILES. ADS SUBMITTED WITHOUT THIS INFORMATION WILL NOT BE ACCEPTED. CLASSIFIED COMMERCIAL RATE: (for firms Or individuals offering commercial products or services) $3.10 per word prepaid (no charge for zip code)... MINI MUM 15 WORDS. 5% discount for same ad in 6 issues; 10% discount for same ad in 12 issues within one year; if prepaid. NON-COMMERCIAL RATE: (for individuals who want to buy or sell a personal item) $2.50 per word, prepaid....no minimum. ONLY FIRST WORD AND NAME set in bold caps at no extra charge. Additional bold face (not available as all caps) SSe per word additional. Entire ad in boldface. $3 70 perword. TINT SCREEN BEHIND ENTIRE AD: 53.85 per word. TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD: S4.50 per word. EXPANDED TYPE AD: $4.70 per word prepaid. Entire ad in boldface, S5.60 perword TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD: $5.90 per word. TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD PLUS ALL BOLD FACE AD: $6.60 per word. DISPLAY ADS: 1" x 2W— $410.00; 2" x 2W'— $820.00; 3" x 2W — $1230.00. General Information: Frequency rates and prepayment discounts are available. ALL COPY SUBJECT TO PUBLISHERS APPHOVAL. ADVERTISEMENTS USING P.O. BOX ADDRESS WILL NOT BE ACCEPTED UNTIL ADVERTISER SUPPLIES PUBLISHER WITH PERMANENT ADDRESS AND PHONE NUMBER. Copy to be in our hands on the 5lh of the third month preceding the dale of the issue, (i.e.. Aug. issue copy must be received by May 5th). When normal closing date falls on Saturday, Sunday or Holiday, issue closes on preceding working day. Send for the classified brochure. Circle Number 49 on the Free Information Card. COMPUTERS AT/XT compatible systems and components at discount prices Catalog $2.00. re- fundwith first order. MPS ENTERPRISES, Box 1048, Lemon Grove. CA 91940. ENGINEERING software, PC/MSD0S. Circuit design and drawing, PCB layout, Logic sim- ulation, FFT analysis, Mathematics, Circuit analysis. Call or write for free catalog. 1 (800) 728-3805, BS0TT SOFTWARE, INC., 444 Coiton Rd., Columbus, OH 43207. Quality Microwave TV Antennas B WIRELESS CABLE - IF IS - MMDS - Amateur TV Uim High Gam 50* (+1 ■ Tuneaole 1.9 to J.T Gin. • 36-Channel System Complete 5149.95 • i:-ClBnnel System Complete SI 14.95 • Cil « write (SASE1 for "FREE" Calaloo. PHILLIPS-TECH ELECTRONICS P.O. Bui 8533 . Scottsdale. A7 85252 : (602) 947-7700 IS3.00 Crcdil ill ptiuii orfiri] WARRANTY MaiterCard ■ Visa ■ COD'S ■ Quurtfty Prtclnf RESTRICTED technical information: Electronic sur- veillance, schematics, tocksmithing, covert sci- ences, hacking, etc. Huge selection. Free brochures. MENTOR-Z, Drawer 1549, Asbury Park, N J 07712. CABLE TV converters: Jerrold, Oak. Scientilic At- lantic. Zenith & many others. "New MTS" stereo add-on: mute & volume. Ideal for 400 and 450 owners! 1 (800) 826-7623, Amex, Visa, M/C accept- ed. B & B INC., 4030 Beau-D-Rue Drive, Eagan, MN 55122. CALL DOCTOR DESCRAMBLER ...for symptoms relating to scrambled cable T.V. signals. We have » JERROLD • TOCOM • ZENITH •HAMLIN 'OAK • SCIENTIFIC ATLANTA. Six month warranty! We snip C.O.D. Lowest retail/ wholesale prices. FREE CATALOG: VISA, M.C., AM.EX. Global Cable Network 1033 Irving St. Suite 109 S.F..CA 94122 NO CALIFORNIA SALES!!! OPEN SATURDAYS m 1-800-327-8544 83 mmm CHOOSE FROM THE FOLLOWING PACKAGES: PKG.1... 10 PANASONIC 1453G CONVERTERS S65 PKG. '2... 8 SCIENTIFIC ATLANTA $17C 8536+ COMBINATIONS* If J PKG. '3... 5 SCIENTIFIC ATLANTA $91E" 8580 COMBINATIONS T fc 111 PKG. 4... Ah MIX AND MATCH ADD-ONS $45" ALL EQUIPMENT IS BRAND NEW, FACTORY FRESH !!! (800)234-1006 CAK||EADV WANTED; old, Western Electric, Mcintosh, Altec, Marantz, Jensen, JBL, EMT, Electrovoice. RCA, Telefunken. Westrex, Fairchild, Fisher, Dynaco; tubes, speakers, amplifiers, (713) 728-4343, MA- URY CORB, 12325 Ash croft, Houston, TX 77035. TUBES, new, up to 90% off, SASE, KtRBY, 298 West Carmel Drive, Carmel, !N 46032. WIRELESS CABLE RECEIVERS 1.9 TO 2.7 GHz 30 CH PARAeOLIC DISH SYSTEM S173.90 30 CH ROD ANTENNA SYSTEM S!93 30 30 CH CrfYSTAl CONTROl LED SVSTEM S»4 -9S SUN MICROWAVE IHT'L. INC. SEND SI. 18 FOR P II f :■!. .1 ■■ v :■ CATALOG OK THESE PHOENIX. AZ 5505? '■«:: OTHER FINE 602 I3D-1M5 VIDEO PRODUCTS OOANIIT* DISCOUNT! Q ORDERS 0HLT 1-BW- W-4190 CODE 9/S3 RADIO software, PC/MSDOS 5.25" 360k disk. 23 programs including subprograms. INTER MOD — RFRANGE — SWRCALC — dBCALC — PA- TH LOSS — more! Great for technicians and stu- dents. Complete package $19.95. SPARTAN RADIO, PO Box 15178, Dept. RE, Spartanburg, SC 29302. TB-3/SB-3 descrambler schematics with service in- formation. $30.00 each. Both for $50.00. S.A.S.E. for samples. JEC TECH, Box 94B, Pickerington. OH 43147. t.C.'S, capacitors, connectors, etc. DYNASTY ELECTRONICS, 200 South Semoran Blvd., Orlan- do, FL 32807. Fax (407) 381-0785. H-P 331 A distortion analyzer $245,00; Boonton 230A power amplifier 10-500MHZ $125.00; H-P 202H AM/FM signal generator 54-216MHZ $350.00; GR 1001 A AM generator 5kHz-50 MHz $235.00; TEK 575 curve tracer $375.00; H-P 7402A strip chart recorder as is $225.00. Older tube type equip- ment bargain prices. Catalog $5.00. EDI, 180 Rodeo Drive, Brentwood, NY 11717. (516) 242-6400. PERFECT CABLE CONNECTION !! Perfect Cable Connection IS tclally commitled to customer saiisfaciiorv Our primary concern is to provide you wilh the highest quality conveners and descramblers at trie lowest cost We employ lull time technicians to insure hassle Iree service and EroubTesnoot any situation. Call us today and let tis prove lo you why we are Irie Perfect Cable Connexion. ■ 6 monlhs 100% pens i labor » 24 monlhs warranly available ■ Foil technical support ' On-line computer sysleiti - 30 days money back guarantee • Most orders shipped within 24 hours • Visa, M'C. AMEX - 5"!i , Dealers welcome ■ COD. CO O WE WILL MEET OR BEAT ANY ADVERTISED PRICE IN THIS MAGAZINE. PERFECT CABLE CONNECTION 702-358-2763 2209 Oddie Blvd., Suite 321 Spark, NV 89431 Try the Bectnmics* bulletin board system (RE-BBS) 516-293-2283 The more you use it the more useful it becomes. We support 300 and 1200 baud operation. Parameters: 8N1 (8 data bits, no parity, 1 stop bit) or 7E1 (7 data bits, even parity, 1 stop bit). Add yourself to our user tiles lo increase your access. Communicate with other n-E readers. Leave your comments on R-E with the SYS0P. RE-BBS 516-293-2283 JEHISBEIE FAMOUS "FIRESTIK" BRAND CB ANTENNAS AND ACCESSORIES. QUALITY PRODUCTS FOR THE SERIOUS CB'er. SINCE 1962 FIRESTIK ANTENNA COMPANY 2614 EAST ADAMS PHOENIX, ARIZONA 85034 TEKTRONIX pie-owned oscilloscopes. 500-MHz model-7904 $3,200.00. 100MHz model-7603 $1,200.00, with plug-ins, JOHN, 8500 Hilo Lane. Cottage Grove, MN 55016. (612) 459-5862. FM stereo transmitters. 88-108 Mhz, assembled, crystal controlled, internal audio mixers. Broadcast quality $100.00 — $200.00. Catalog: OREGON COMSYSTEMS, 1257 Siskiyou, Suite 132, Ash- land, OR 97520. ■M:1=M.».I.1WI3=E« We specialize in a wide variety of technical information, parts and services for CB radios. 10-Meter and FM conversion kits, repair books, plans, high-performance accessories. Thousands of satisfied customers since 1976! Catalog $2. CBC INTERNATIONAL P.O. BOX 31500RE, PHOENIX, AZ 85046 BRAND new Tektronix 2247A 4-channel os- cilloscope. Never been out of box w/Quickpak. Will sacrifice (402) 438-3318. PHOTOCOPIER theory and repair manual. Secrets revealed. $19.95 LOTUS PUBLISHING, Dept. S, Box 1689, Guelph, Ont. N1H 6Z9. CABLE TV converters and descramblers. We sell only the best. Low prices. SB-3 $79.00. We ship C.U.O. Free catalog. ACE PRODUCTS, PO Box 582, Dept. E, Saco, ME 04072. 1 (800) 234-0726, CABLE descramblers (Jerrold) from $40.00. Tocom VIP test chip. Fully activates unit. Also Zenith test board. Fully activates Z-Tacs. $50.00. Call (213) 867-0081. ANTIQUE RADIO CLASSIFIED Free Sample! ^^^f^&i Antique Radio's i^^OqjQjp Largest Circulation Monthly, [B@W o I Articles, Ads & Classifieds. ■ ^lv*«B | j 6-Month Trial: $15, 1-Yr: $27 (S40-1st Class). A.R.C., P.O. Box 802-L9, Carlisle, MA 01741 TV. notch filters, phone recording equipment, bro- chure $1 .00 MICRO THinc. Box 63/6025, Margate, FL 33063. (305) 752-9202. PHOTOFACT lolders under #1400 $5.00. Others $7.00. Postpaid. LOEB, 414 Chestnut Lane, East Meadow, NY 11554. (516) 481-4380. CABLE CONVERTERS all major brands info + orders 1 (800) 782-0552 FREEWAY INC. s.m.p.. PO 5036, Burnsville, MN 55337. PAV TU AMD SATELLITE 0ESCRAMBLING ALL NEW 1991 EDITION Our best yet The very latest in descrjm'biinfl circuits, bypasses, lutn-ofls- (or dote, wireirss gn-d satellite. Only $1 A .95-. Otter cay TV edirJpns-. Vol. i (Basics Ol All Svstemsj $14.95. 1909 Edition $14.95. Build satellite systems under S60D $1 2.95. Wireless Cable Handbodn s& 95. Any 1-W9 95 or 5#44,95. SciamblinQ News Monthly has all into f n the new "Plain Vamfla" dpscf-amWEfs which Em- ulate B'Wias VCii. Plus and Qriarv. $I9.95/Yr All new catalog £1 Scrambling News. 155! Hertel Aue.. Buflalo. NY. 14216. COD'S ARE OK. (716) 874-2089 SUPER low prices on computers, motherboards, hard and floppy drives, add-on cards. We have ev- erything. Full line of test equipment at unbeatable prices. Call for free catalog. APPLIED ELEC- TRONIC RESEARCH, INC., 4701 SW 45th Street. Ft. Lauderdale, FL 33314. (305) 987-9785. 84 / ELECTECH / CABLE T.V. DESCRAMBLERS • All quality brand names • • All fully guaranteed • All the time ■ Knowledgeable Sales Sen/ice Department FOR FREE CATALOG 800-253-0099 CIRCUIT Center — Complete circuit fabrication from single piece single sided to production multi- layer. Also — Laminate $5,50/sq. ft., etch $3.50/qt. Thru hole plating available too. CIRCUIT CENTER, Dept. 001, PO Box 128, Addison, IL 60101. (708) 543-0671. PREVENT descrambler detection! Order Tech- Block today! Simple in-line connection. Only $19.95 P.P.D. THE STAGE DOOR VIDEO, PO Box 518, Belleview, FL 32620. ForC.O.D.*s1 (800)395-4557. INTERFERENCE fillers, all channels. Best quality, cylinder type. Low prices. Visa, MC, COD accepted. 1 (800) 872-5912. EXOTIC miniature electronic devices, catalog $5.00. refundable. F&P ENTERPRISES, Box 51272, Palo Alto. CA 94303-L AC motor speed control — UL listed, 15A. 1 20/220vac, dual independent inputs tor stall speed limit and thermistor probe included. Range 80°F minimum speed, 140°F maximum speed. $29.95 plus $4.00 S&H. CONTROL OPTIONS, INC., 3298 S. Acoma, Englewood, CO 80110. (303) 761-5927. SENCORE SC-61 waveform analyzer just factory updated $1500.00. BLS, PO Box 230014, Tampa, FL 33682. TECHNICIANS, hobbyists. New affordable pro- grammable power supply. For brochure contact: AMERICAN DIGITAL SYSTEMS, INC., PO Box 22953. Denver, CO 80222. Tel Fax 1 (800) 424- ADSI. 7 v \ f roc -K * * * PRESENTING it - CABLE TV DESCRAMBLERS ***** STARRING ***** JERROLD, HAMUN, OAK AND OTHER FAMOUS MANUFACTURERS • FINEST WARRANTY PROGRAM AVAILABLE • I CM/FIT RFTAII /WHOLESALE PRICES IN US • ORDERS SHIPPED FROM STOCK WITHIN 24 HIS • ALL MAJOR CREDIT CARDS ACCEPTED FOR FREE CATALOG ONLY 1 SOO-34 5-892 J FOR ALL INFORM ATJON 1-8 1 B~709-993 Tj PACIFIC CABLE CO., INC. 7325' a Reseda Blvd.. Dept. 2106 Reseda, CA 91335 CABLE TV descr am biers converters, wholesale to all,weshipC.O.D.,examplesOak RTC-56 $125.00, M-35-B $35.00, X-12 $29.00, FTB-3 $69.00, Tocoms, Zenith, Jerrold, Hamlin, SA, etc. S.A.C., 1 (BOO) 622-3799. RAW cable equipment, as is, Z-tac $35.00. RTC-56 $45.00. M-35-B $18.00, Tocom $65.00, Texcan 4040 $25.00, 400 QIC S25.00, same day shipping. (702) 647-3799. ELECTRONIC supermarket great buys! Surplus prices! Railroaders, builders, engineers, experi- menters, LSASE, FERTIK'S, 5400 Ella, Phila- delphia, PA 19120. TOCOM-Jerrold Impulse-Scientific Atlanta 8580 & 8590 converters with two yr. warranties, also test modules for Star Comm 6 & 7s, all Tocoms, and Scientilic Atlanta. Full details. (219) 935-4128. DESCRAMBLERS cable TV converters, lowest prices, guaranteed, best quality, special Sacramen- to units. CNC CONCEPTS, INC, Box 34503, Min- neapolis, MN 55434. 1 (800) 535-1843. CBTV converters: Jerrold JSX DIC $19.00 DRX replacement (4040) $39.00, M35B $19.00, RKDM S55.O0, other brands in stock, minimum 10 lots 1 (800) 395-2225. TOCOM and Zenith "test" chips. Fully activates unit. $50.00. Cable descramblers from $40.00. Orders 1 (800) 452-7090. Information (213) B67-0081. REMOVE LEAD VOCALS . From R»eortis& CD's Quid 9, 14 kit for uridw &G0 Mil*** mum* lead vocaje from slandanj stereo records. CD's, tapec or FW Lxoadceala. Easily conned* to any horn* component atweo. Perform live wift m* background*. You can be lia load singer at your Favorite band. Battled Plana. (4.95 Weeds r Technologies 14773 Llndwy Rd Ml Orab, Ohio 45154 . PLANS AND KITS DAZER personal protectors! Lasers! AM/FM/ln- frared transmitters! Detectors! More! Kits/as- sembled. Catalog $2.00. QUANTUM RESEARCH, 16645-113 Avenue, Edmonton. Alberta T5M 2X2. SURVEILLANCE — Audio/video/infra-red/laser equipment. Industrial or private. 500 item catalog $7.00. SECURITY SYSTEMS, 3017G Hudson PL, New Orleans, LA 70131. REMOTE CONTROL REYCHAIN Complete w'm1nl-4fBnBmiUe' i: :: : fltid +5 vrfc RF. receiver:;:; Fully assembled including plans to build your own auto alarm;;; Qua niHy. d isco unts sya il a ble /•. r\c Cheek,vja» ortnVC 5>«i4.yO :- AcW S 3 shipping : Sox 14156, Fremont, C« 94539 Fax (415) 531^-8442 VISITECTINC, (41 5)531 -3425 4 MITSUBISHI r» ELECTRIC ►HER S/WtS flcqmmc arist.: SONY Welle HGaR roblemotic SIIRIICI ( B A It £ m EPC PIONEER MCM Electronics We Can't Help Mentioning A Few Names Although name-dropping is usually frowned upon, we'll risk it so you'll know the kind of company we keep... and that you can get almost any part you could ever want from our huge MCM Catalog. Choose from more than 17,000 items, most of them in stock and ready to ship within 24 hours! Talk to friendly, knowledgeable | sales reps, get technical help when you need it and enjoy convenient, TOLL-FREE order- ing. All GREAT reasons why you | should be keeping company with MCM too! Call TOLL-FREE, 1-800-543-4330, NOW to get your FREE SUBSCRIPTION to the MCM Electronics Catalog t£fi l ^%a^H lMCM electronics a SPRING -1991 ^- 4 %c^ MCM ELECTRONICS B50 CONGRESS PARK DR. CENTERVILLE, OH 45459-4072 A PREMIER Company DURACELL CRAMOUN RocKet FLUKE ■aaaaaaaaaaaaaaaaaB CIRCLE 87 ON FREE INFORMATION CARD CO m 13 co m 3D ID to 85 Cable Descramblers New Auto Tri-Bi guaranteed no flashing $165.00 SB-3 399.00 ZENITH SUPER TRIMODE $109.00 SAAVI 1199.00 SIAMLtN S99.00 TOCOM S319.00 SCIENTIFIC- EAGLE $119.00 ATLANTA S119.00 COPV GUARD $59.95 O AK M35 B. ... $99 .00 STARG ATE 2000,,, $S3 .00 ZENTTH $175.00 M-D. Electronics will match or beat any advertised wholesale or retail price. Your best buys and warranties fur cable converters and descramblers start uitli a FREE catalog from Ml) EXCELLERATOR CABLE CONVERTERS WHEN QUALITY COUNTS For In form at ion Call 402-554-0417 To order or request a free catalog 1-800-624-1150 t $& mt *%* *> "B New Dynatrack™ fine tuning' provides unmatched picture quality S5& Mhz tuner provides S3 channel capacity Sleep timer for automatic shut off within 15-90 minutes 2/3 switchable HRC / IRC ■■ Standard Switchable 2 Year warranty, Last channel recall. Favorite channel select, Scan Double vented high efficiency transformer for cool performance Stargate^2001 $99.00 Stargate-550XL $119.00 With Volume Control Don't settle for anything less. MmiEtmmmmms^ ffl 91 C.O.D. 875 SO. 72nd St. Omorw^NE 68114 JYCWJOUNCCMLE TV tCATTTttlNTFECM UD ELEC7BONKS 71 IS PUKTt laSKI* AGREES TOCCMPLY WITH ALL STATE ANO E&CT RAL LAWS RfiCARULVCl ITUVATE OWSSHIPC* CAlLE TV EOLTPMOTT. IF YOU ARE UNSURE OF THESE IaWS CHECK WITH TOUR LOCAL OFFICIALS. CIRCLE 53 ON FREE INFORMATION CARD FREE cable and satellite descrambler plans. Send self addressed stamped envelope. MJM INDUS- TRY, Box 531, Bronx, NY 10461 -020B. HOBB Y.'b roadcasti ng/H AM/C B/surve i llance trans- mitters, amplifiers, cable TV, science, bugs, other great projects! Catalog $1.D0. PAN AXIS, Box 130- F9, Paradise. CA 95967. BUILD from simple materials, over 100 mites per gallon carburetor. Detailed plans, five versions. Good science project. $20.00 Visa welcome. (902) 467-3577 VALLEY MICROWAVE, Station C, Bear River, N.S., Canada BOS 1B0. 03 O ■z. & 5 id 6 < I'LL HAVE MINE DESCRAMBLED If you find a better deal, We'll beat Itl JERBOLD * TOCOM • HAMLIN • OAK ■ SCIENTIFIC ATLANTA • ZEWTTH • ask about our warranty program C.O.D. Visa, M/C, AM.EX. welcome. -FREE CATALOG • FREE CALL •OPEN SATURDAYS 1 800 562-6884 VLTJEO TECH 3702 S. Virginia St. Ste. 160-304 Reno, NV 89502 INVESTIGATORS, experimenters — Quality new plans. Micro and restricted devices. Free catalog. Self addressed stamped envelope required. K EL- LEY SECURITY, INC. Suite 90, 2531 Sawtelle Blvd., Los Angeles, CA 90064. TELEPHONE caller identifiers. Displays incoming caller's telephone number, kit $49.95 postpaid, SURVEILLANCE catalog $5.00, EDE, POB 337, Buffalo, NY 14226. DESCRAMBLER kits. Complete cable kit $44.95. Complete satellite kit $49.95. Add $5.00 shipping. Free brochure. SUMMIT RE, Box 489, Bronx, NY 10465. No NY sales. CABLE TV DESCRAMBLER LIQUIDATION! FREE CATALOG1 Hamlin Combos S44, Oak M35B SS0 (mln. 5), etc. WEST COAST ELECTRONICS For Information: 818-709-1758 Catalogs & Orders: 800-628-9656 DESCRAMBLING, new secret manual. Build your own descramblers for cable and subscription TV. Instructions, schematics for SSAVI, gated sync. sinewave, (HBO, Cinemax, Showlime, UHF, adult) $12.95, $2.00 postage. CABLETRONICS, Box 30502R, Bethesda, MP 20824. SMD How to use surface mounl technology. Build ultra miniature projects. Plans included free, infra red control, and an interesting light display. Send $15 00 to CHARLIE'S VIDEO, Dept, SRT, PO Box 7782, La Sierra, CA 92503. HYPNOTIZE or Relax electronically! Alpha/medita- tion goggles. Complete kit $53.00. Free information, MARK WORLEY, Box 261113, San Diego, CA 92196. SURVEILLANCE transmitter kits tune from 65 to 305 MHz. Mains powered duplex, telephone, room, combination telephone/room. Catalog with Popular Communications, Popular Electronics and Ra- dio-Electronics book reviews of "Electronic Eavesdropping Equipment Design," $2.00, SHEFFIELD ELECTRONICS, 7223 Stony Island Ave., Chicago, IL 60649-2806. CABLE DESCRAMBLERS OAK M35B COMBO S39.95 JerrolrJ, Zenith, Hamlin, Sci. Atlanta, Pioneer & MORE! OUR PRICES ARE BELOW WHOLESALE! CABLE-+- PLUS 14417 Chase St. #481 -A Panorama City, CA 91402 1-800-B22-9955 • Other Info. 1-818-785-4500 NO CALIF. SALES - DEALERS WANTED BUILD subwoofers for home theater. $ave. Com- plete instructions $6.95 WILLIAM CROWLEY, 2118 Wilson, Hollywood, FL 33020. PCB and schematic CAD. $195.00 IBM EGA CGA Multilayer, rubberband, autovia, NC drill, laser, dot matrix, plotter, library, Gerber, AUTOSCENE, 10565 Bluebird St., Minneapolis, MN 55433. (612) 757-8584 free demo disk. VIDEOCIPHER I l/scanner/cable/satellite modifica- tions books. Catalog $3.00. TELECODE, PO Box 6426-RE. Yuma, AZ 85366-E426. DIGITAL recorder. Digitally record any audio source with special effects. Microprocessor con- trolled device. Detailed plans, $9.75: T. ZURAW, Box 341, Dearborn Hts, Ml 48127. REMOVE VCR copy protection, PCB PAL instruc- tions$16 50 w/P&H, LOGICAL CHOICE, Box 1256, Lomita, CA 90717. VCR repair kits. Free catalog: SMS ELEC- TRONICS, PO Box 0190, lompOC, CA 93436-0190. CALL display number of person phoning. Informa- tion on how it works, one chip circuit interfaces to computer, includes format, schematic, parts list, suppliers, Basic&C source, send $15,00 U.S. XANTHIC, 454 12th St. SW, Medicine Hat, AS, Can- adaT1A-4V1. TESLA coil. Completely solid state. Sparks over 15 inches with 10 inch long coil! Plans $10.00 CORO- NA COIL, PO Box 474-D. Riverton. Utah 84065-0474. TELEPHONE bug FM plans. Convert Radio Shack device easy, $8 00. ALLAN LABORATORIES, PO Box 14302, Research Triangle Park, NC 27709. TELECOMMUNICATION projects. 600 page de- tailed book. Modems, telephones, PCM's, switching systems, data, DTMF, more. $17.95 COMSPEC, 200 Bay Street South. Box M3, Hamilton, Ontario L8P-4S4 Canada. LIGHTING — Complete portable lighting system perfect for stage lighting, exhibits, special events. Plans/application notes $5.50 ACS, 6220 Shal- lowford Rd. #152, Chattanooga, TN 37421. THE electronic defender an effective, non-lethal de- terrent to those who wish you harm. It will protect you and your properly. Detailed plans $6.95. Parts & PC board also available. TYLER ELECTRONICS, PO Box 493, Richmond Hill, NY 11418. KEYTRON amazing electronic keyhook, saves lost key problems, also reduces healing/ac bills, kit $19.95. Assembled $29.95, plans $6.00. Info pack- age $2.00 credited to firsl order. MERLIN TECH- NICAL COMPANY, Box 44213, Boise, ID 83711. BEST BY NAIL Ratal: Write National, Boa 5, Sarasota, FL 34230 OF INTEREST TO ALL $48,900 INCOME and HAWAII 1 1 Free Report: 480(RE) Hawl, Hawaii, 96719. CASH LOANS UNSECURED to S1C,0O0, No Cred! Check, 1-800-3aB-B878, Dealer Inquiries Welcome. HAIR LOSS? INFORMATION about new trealmenls Pater Proctor, MO 1.60O-926.1752. VCR REPAIR - TECH NIC ANS' SECRETS REVEALED Do it yourself, literally save hundreds. Complete easy it follow manual. Includes 800 numbers of all majo manufacturers lor ordering parts direct SchemalicsJDiagrams. More. $9.95 to: ACME VCI REPAIR, 2104 Benwiok Lane, Aniioch. CA 94509. 86 WHY PAY SKY HIGH MONTHLY * RENTAL? * Pay down -to-ea rtli prices Tor cable TV descram biers. If you find a better deal, we'll beat it! • Hamlin • Jerrold • Oak * Sci entitle Atlanta * Tocom • Zenith. Ask about our warranty program. C.O.D. Visa, M/C, AM.EX. welcome. • Free Catalog * Free Call • Open Saturdays GTV 1464 Garner Station Blvd. #315 Raleigh, NC 27603 1 800 328-0198 SATELLITE TV FREE catalog — Lowest prices worldwide. SKYVI- SION, 2009 Collegeway, Fergus Falls, MN 56537. 1 (800) 334-6455. (See full page ad in The Shopper section) VIDEOCYPHER II descrambling manual. Scht> matics, video and audio. Explains DES, Eprom, Clonemaster, 3 Musketeer, Pay-per-view (HBO. Cin- emax, Showtime, adult, etc.) £16.95, £2.00 postage. Schematics for Videocypher Plus. S20.00. Sche- matics lor Videocypher 032, S15.00. Collection of software to copy and alter Eprom codes. £25.00, CABLETRONICS, Box 30502R, Bethesda, MD 20824. CABLE TV Secrets — the outlaw publication the cable com panies I ried to ban . HBO, M ovie C h annel , Showtime, descramblers, converters, etc. Sup- pliers list included. £9.95, CABLE FACTS, Box 711- R, Pataskala. OH 43062. FREE catalog — Compare our prices for new sys- tems and upgrades. Latest receivers and dishes — all top brands. ALPHA SATELLITE DIST, PO Box 197A. Hawthorne, NJ 07507-0197. 1 (800) 535-AL- PHA. ANNOUNCING: AN END TO HIGH MONTHLY CABLE FEES! All Jerrold, Oak, Hamlin, Zenith, Scientific At- lanta, Magnavox and all specialized cable equip- ment available for shipment within 24 hours. For fast service MC/VISA or C.O.D. telephone or- ders accepted. 60 Day Guarantee (Quantity Dis- counts). Send self -addressed Stamped enve- l0 ^ 1-800-232-5017 WW COD. ORDERS L^™ ACCEPTED CABLETRONICS, INC. 1304 E. Algonquin Road Suite 501 Algonquin, Illinois 60102 mmmmmmmmmmm A -f leetrBiiirj Qr JSC mmmmm mmmmmmm Your Ticket To SUCCESS Over 28,000 technicians have gained admit- tance worldwide as certified professionals. Let your ticket start opening doors for you. ISCET offers Journeyman certification in Consumer Electronics, Industrial, Medical, Communications, Radar, Computer and Video. For more information, contact the International Society of Certified Electro- nics Technicians, 2708 West Berry Street. Fort Worth, TX 76109; 1817) 921-9101. Name Address City State Zip Send material about ISCET and becoming certified. Send one "Study Guide for the Associate Level CET Test En- closed is $10 (inc. postage). MARK V €L€CTRONICS, INC. Competitive Pricing * Fast Shipping Since 1985 ORDER IN CALIFORNIA 800-52 1 -MARK ORDER OUTSIDE CA 800-423-FIVE FREE CATALOG & INFORMATION (213) 888-8983 FAX (213) 888-6868 ▲ indicates the level of difficulty in the assembling of our Products. A Beginner AA Intermediate AAA Advanced * Fully Assembled TA-1000A Due iq this specral oiler £ low price we can only oxefianoG or repair any ol Irrase units (TA-36QO, TA-477 TA-802 & TA-tOOOA} within 1 S days or your receipt. rr-.e above prices are tor ih» complesa sals For separate unit pckM. please see below "Transformer AMPLIFIERS KIT ASSEMB. MISCELLANEOUS KIT ASSEMB MODEL IA-28MK2 TA-50A/6 TA-50C 1A-120MK2 1A-3Q0 SM-302 TA-323A TA-377A TA-4W TA-477 1A-8O0MK2 TA-802 TA-1000A TA-1500 1A-2J00 TA-24O0A 1A-2500 TA-2B0O 1A-30OO TA-3S0O sum S ',1-328 5M-333 SM-66G SM.E33 DESCRIPTION Digilal Voice Memo AA Mul 1 1- Purpose Melody GeneratDt A Mulh.PuipMe Melody (Happy Binhday Wedding March. elcl Generator 35W Class "A' Mam. Power Mono Amp. A A . . . .. 30W Mulli-Purpose Single Channel Amp A — , SOW r SOW Stereo Power Amplilier |wilh Mir. input) A A SOW * 7 Slereo Pfe-main Amp A Stale ol lire An Fully Complementary Symtnelrical F£T Pit-Amp AAA sow Solid Slaw Mono Amp a _ 120WMos1et Power Mono Amp. AA __,.. 120W t UOWlow Tim Pte-Mim Stereo Power Amp AA SOW * 30W Pure DC Stereo Mam Power Amp AA IMW Dynamic Class "A" Main Power Mono Amp AA . ItBW X 2 Class "A' DC Stereo Pre- Mam Amp AAA DC Fet Super Class "A - DC Pie-Amp AAA „, „ , EteclTOn.'t Echo fi RevereeratioriA Tip * .. HO Pre-Amp w: 1 0a nd graphic equalizer * 61-FET IC Pre-Amp w/3 way lone control A A . 5 30 05 .. 12.64 A 13 66 . 31 50 . 20 00 67.00 .3150 59 95 ..26 00 ..68.00 63.92 15 94 .50.09 73 TO . 47.70 Stereo Simulator (for Mono TV or Any Mono Source) AA 30QW HO Hi-Fi Power Motto Amp AAA 7 Band: HI-FI Graphic Equalizer a a a 4 Channel Protessionat Color Light Controller* AuOioAtideo Surround Sound Processor AAA* Dynamic Naise Red lc tier. A universal Audio/Video KAflAQKt Mixer Pre-Amp. * 46.90 .27 00 65.60 65 00 76 00 17,20 11.71 42.60 3- at 7600 42.80 7S00 34 93 65.00 59.7! "BOSS 95 81 5S24 9609 Eaao 6357 35.50 110.00 3SSII 145.00 ■5 on 34.00 225 00 MODEL TY-23B TY-25 TY-35 TY-36 TY-38 ■■ -■'-•• . ly-4! TY-43 TY-4S, TY-47 lO.OOOufl DESCRIPTION 3 Channel Color Liphi Controller * Stereo Loudspeaker Prelector A .. . FM Wrreiess Microphone A ACrDC Quartz Digital Clock A Sound / Touch Control Swilch A Inlrareo flemole Conlrol Unit |w.'Caset A A A 8ar I Dot Level Meier a a 3'vDigilal Panel Meier A .■0 Sleps Bat t Dm Audio Level Display AA Superior Electronic Roulette AA . .. , 80 V Capacitor (Suggested lor TA-3600. TA-477. TA-iOOOA & TA-802] . ..14.B5 ..11.26 13.00 1200 22 00 ..24.15 29.00 39.45 19.46 S 65.00 20 95 2E20 35 00 33 81 36 00 46.14 27.24 23.00 REGULATORS KIT ASSEMB, TB-355A 0-15V 5A Bejufflea DC Power Supply mo case 6 x'lotmer] A SIS 65 S II 76 TH-3S5B O-30V 3A BegutalKJ DC Power Supply mo case a xlormeri A . .15 65 21.75 0-50V3A Regulated DC Power Supory ino case S xlormertA a 16.7S !3.65 METAL CMINETS WITH ALUMINUM PAHEl MODEL LG-1273 LG-16J4 LG-1924 LG-I9J5 rTiVT i D- MATCHING TA-280O.TA-377A, 1A-22O0 TA-323ATA-377ATA-220O.. r 8' I1H TA-802 1A.15O0.TA110MK2.TA-80OMia. TA-IOOOA 11H TA-477, TA-atJO. MK2. TA-150O. TA-IOOOA. TA-3600 r TA-377A IA-2800 1A-22O0. IA.I20M«2 PRICE S2365 27 50 .. 33M . 35 80 ... 29.25 POWER TRANSFORMERS DIGITAL METERS AND COUNTER KIT ASSEMB. SM-43 SM-43 SM-48A SM-49 SM-100 it Mull, functional Led P M iwABS rustic casi). t .■ Hr-Precisiorr B ? M A A A 4-.. Hi -Precision D P M. |w/ASS plaslie caiekAAA i-t Mulh-furiclionil LCD D M P (w-'Hold FunclnmlAA . tSOVC Dig Jit Frequency Counltr AAA S34 50 38 00 41 20 3600 79 00 S43 00 48.00 52 00 44 50 90 00 MODEL 001 m 333 KM 035 B06 DESCRIPTION 25V X 2 6A to 30V 1 2 BA 36K X 1 3A 40V 1 2 6A 24Vi26A 2EV«2 3A MA - :.!' \r- PRICE TA-600 MK2, TA-802 TA-620A. TA-1D0OA. TA-1500 . S 27 00 TH-S03, TA-323A. TAJOO, TA-300. TA-377A 22 00 TA-477 29.00 TA-120MK! 22 03 TR-355B 16.00 TR-355A 15.50 IA-3600 43 00 09 rn ■o H m m m 3 Wy jcxep* m^jr Cirms.l Cardi . J,toftir OWwns. Chaclii and C.O.D OrdoraCO-tJ frt^SSOO. S^mumcftJwrjS^W.-WejnflbrUPSgrt^n^ $3 M) and ttop Oy US ma* BuStrtfc*SS &■ ShOwrODlTl hOurS: (FaCHlC Time) Oijn4tlJS i^AjWaUGrijrHtfeniMpiulm *AHa5Si>mWEfliiniriiiivni«a3QdjyiWjTtfriir^ Mofl. ItlfU Ffi. 9'30 am 10 5-00 pTtl ■QtC-Ap*aE*aMSdia-ie4tai.6 79% < AJi mgtt-Jiam i-tg £ fnrcbj tern tul^a to p* 18" Eminence Woofer The perfect high volume cabinet for dual voice coil subwoofers. Sox comes with pre-cul wooler and port holes. Cabinet volume: 2 cu. ft. with dual ports. Charcoal carpet. Dimensions; 13" (H) x 13" (D) f 30" (W). Net weight: 29 lbs. Piezo midrangertweeter driver unit. Response: 800-20 KHz. Power handling capability: 20-30 volts (approximately 50 waits RMS). Sensitivity: 93 dB. 2.83W1M. 4" round Motorola *KSN 1086. #RL-260-495 $59 90 Each #RL-270-085 $25 30 (1-3) $23 95 Professional driver lor use in auditorium and studio sound sysloms. Giant 100 oz. magnet. 250 watts RMS. 350 watts max power handling capability. fs. 30 Hz, QMS= 3.17, OES=. 373, QTS= .33. VAS. 10.5 cu ft SPU95dB1W/1M. Net weighl: 29 lbs. ( i (4-up) EMINENCE #RL-290-200 $99 B0 $93 40 H'Upl 12" Pyle Woofer 5-1/2" Cone Midrange Gw PYLE 12*. 70 oz. magnet woofer. 2-1/2" voice coil. 105 watts RMS. 155 watls max power handling capability. #RL-292-050 $59 80 (6-up) Original Sanyo high end system midrange, Large 5" paper cone with gold took dust cap. Heavy 12oz. magnet. 1" ferro Huid cooled voice coil. 50 watts RMS. 75 watts max, Sanyo pari #S12HlO. Net weight: 1-1/2 lbs. #RL-2S1-100 f SASYO $5- $3 95 (1-9) (10-up) Subwoofer Crossover Network s-^ i-n> NEW A revised j catalogV^ Super duty, 200 watt RMS power handling capability. Designed specially for duat voice coil subwoofer systems. 12 dS per octave roll-off al s%t ^^ 150 Hz inlo 8 ohms. Crossover also fealures a set of oulpuls for use with your existing speaker system. Network is totally passive, requiring no power source of its own. X NEW J^ $ BEVESED -f -^VCATALOG^ #RL-260*220 $28 B0 (1-5) $24 95 (8- up) f^p^tS 5 ** \ 340 E. First St.. Dayton, Ohio 45402 Local: 1-513-222-0173 FAX: 513-222-4644 ■15 day money back guarantee ■ SI 5.00 minimum order • We accept Mastercard, Visa, Discover, and C.O.D. orders. ■ 24 hour shipping ■ Shaping charge - UPS chart rale + 51,00 [53.00 minimum charge) • Hours 8:30 am - 7:00 pm EST, Monday - Friday ■ 9:00 am - 2:00 pm Saturday. Mail order customers, please call for shipping estimate on orders exceeding 5 lbs. Foreign customers please send $5.00 U.S. funds for catalog postage. CALL TOLL FREE 1-800-338-0531 FREE CATALOG Co m 00 m 33 oo CIRCLE 56 ON FREE INFORMATION CARD 89 ,e*ice sot >™- Of PNW Welcome to. . . „ to FVeteots SCIENCE The /Imateur Scientist's Journal Embark on art irresistible new journey into the realm of mystery, challenge, and exploration! The perfect magazine for the budding scientist, the serious amateur, the professional who would like to relax, and those who simply want to gaze at the stars. Science PROBE! — the only magazine devoted entirely to Amateur Scientists! If you are fascinated by sci- ence in all its many forms ... if you can't stay away from a microscope, tele- scope, calipers, or test tube — we in- vite you to share the wonders in every issue of Science PROBE! You will join a community of Amateur and Student Scientists who enthusiastically seek scientific knowledge or follow scientific pursuits for their own sakes and not merely as a profession. Obtain your next issue of Science PROBE! by visiting a quality News- stand, Convenience Store, or Super- market or by reserving your personal copy through the mail by completing the coupon beiow. From your very first issue of Science PROBE! you will be involved in a world of scientific facts, experiments, and studies pursued by amateur scientists who are university students, investors, academicians, engineers, or office workers, salesmen, farmers — whose quest is to probe into the mysteries of science and reveal them to all. Plan to become a Science PROBE! reader! Articles to appear in upcoming issues of Science PROBE! are: How an Amateur Mapped the Milky Way Make your own Seismometer Operate a Solar-powered Weather Station Grow Crystals Automatically Experiment with a Saltwater Aquarium How to Keep a Science Notebook If you're fascinated by science in all its many forms, if you are compelled to experiment and explore, then Science PROBE! is your kind of magazine! Science PROBE! 500-B Bi-County Boulevard Farmingdale, NY U735 Please forward ray copy of Science PROBE! as soon as it comes off the press. I am enclosing $3.50-U.S.A_ ($4.23-Canada-includes G.S.T.) plus $1.00 for shipping and handling. Better still, please enroll me as a subscriber and send the next four (4) quarterly issues of Science Probe. I am enclosing $9.95- U.S.A. (Canada: $16.00— includes G.S.T.) D Next Issue Only D Next Four Issues (1 Year) Offers valid in the U.S.A. and Canada only. No foreign orders. Name I . I I | City . State . | All Orders payable in U.S.A. Funds only. I Address . _ZIP, 7RJ11 ON SALE AT QUALITY NEWSSTANDS, CONVENIENCE STORES AND SUPERMARKETS GET YOUR COPY TODAY— $3.50-U.S.A.— $3.95-Canada We Have QUALITY PARTS • We Have DISCOUNT PRICES - We SHIP FAST m This simple device can be set to click from 20 to 1.000 beats per minute. Easy to build, includes circuit board, all components and instructions. Oper- ates on a 9 volt battery {not included). CAT* METRO 1375 each PHOTO RESISTOR 1 .000 ohms bright light. £© 16K ohms dark. ifl 0.1B2-dia, X .OS-high. 0.1 S" long leads. CAT*PBE-7 2 lor $1.00 100 lor $45,00 • 1000 lor $400.00 ORDER TOLL FREE 1-800-826-5432 FAX (81 8) 781 -2653 • INFORMATION (81 8) 904-0524 Call Or Write For Our Free 64 Page Catalog Outside the U.S.A. send $2.00 postage for a catalog. Minimum Order $10.00 • All Orders Can Be Charged To Visa, Mastercard Or Discovercard • Checks and Money Orders Accepted By Mai! • California, Add Sales Tax • Shipping And Handling $3.50 for the 48 Continental United States - All Others Including Alaska, Hawaii, P.R. And Canada Must Pay Full Shipping • Quantities Limited • No COD. • Prices Subject to change without notice. MAIL ORDERS TO: ALL ELECTRONICS CORP • P.O. BOX 567 • VAN NUYS, CA 91408 CIRCLE 107 ON FREE INFORMATION CARD Winning Products a Test/Measurement and Prototype Equipment 51-Piece Electronic Tool Kit Global Specialties Proioboard Desic Tools Included in Kit: • 10' measuring tape ■ 5,25" needle nose pliers • Electric tape ■ Utility components box • 6 piece precision screwdriver sel ■ 6" long tweezers ■ 8 piece he* key wrench set ■ 7" brush and scraper ■ Digital Multimeter ■ Brush • T tire point probe • Round needle lil e • to piece screwdriver set: S Slotted £ 4 Phillips ■ 7" slotted probe ■ Flat needle lile ■ 4.5' diagonal cutting pliers MS305 24HOUT. [^151 6" adjustable wrench 30 Wall soldering iron 5.5" Stainless sleel scissors Soldering stand Rosin core solder 5.25" Flat nose pliers Utility knife with extra blade Desoldering pump 5.25" Beni needle nose pliers ■ Carrying case: 17.63"Wx12.5-Dk3.5"H 592- : Features: • Ideal for analog, digital and microprocessor circuits • Triple DC regulated power supplies. +5V. +15V, -15V • S logic indicators ■ Function generator with sine, square, triangle and TTL waveforms ■ Two debounced push-button swilche: ■ Two SPDT slide switches, all leads available and uncommited • A total of 2520 uncommited tie-points • Potentiometers: one 1 Ku and one 1 ■ Includes power supply, instrumental!! and bfeadboardi ng Jameco Logic Pulser Jameco Logic Probe $119.95 PB503 $29' ■ Compalible with TTL. DTL. RTL. HTL. ■ Max Frequency 8QMHz » Minimum detectable HNIL MOS and CMOS ICs. * 1M£I Sync pulse: 10ns - 120K12 inpul impedance ■ Max. input impedance * Pulser mode ouipul supply vgilage: 25V * TTL threshold [Lot -0.8V current: 10mA ■ Square wave curfenl I -0.1V (Hi) ,2.3V -G-2V • CMOS threshold: output: 5mA ■ Audible lune ' I Lot 30% VCC '10% (Hi) 70%VCC 10% Soldering and Desoldering Stations 60 Watt Analog Display Soldering Station ■ Electronic temperature control trom 200- to 878 F ■ Cartridge heat- ing element for a longer life of the soldering tip XY1683. ....$69.95 30 Watt Electronic Temperature Controlled Desoldering Station - Electronic temperature control from 212 to 842 F ■ Self contained high rotary vacuum pump LP540. .$16.95 MS104 $24.95 XY999 $299.95 Prototype Products Jameco Solderless Breadboards -CXs Dirt- CoiUiT:: Binding L"x.W Poims Posts Price Metex Digital Multimeters A.R.T. EPROM Programmer General Specs - ' Handheld, high accuracy * AC DC voltage. AC DC currenl. resistance, diodes. Continuity, transistor nFE ■ Mannar ranging w overload protection M3650 & M4650 only: * Also measure frequency and capacitance M4650 only: ■ Data hold swaieh ■ 4.5 dtgii JE21 3 25 i 2.125 JE23 6.5 1 2 125 JE24 6.5 1 3 125 JE25 6.5 1 4 25 JE26 5,875 1 5.75 JE27 7.25 « 7.5 JfJO S S4.95 830 S6.95 1 360 2 $12.95 1.660 3 S17.95 2. 390 4 $22.95 3.220 4 $32.95 M3610 M365D M4650 3 5 Digit Mullimelet S59.95 3 5 Digit Multriele* w Frequency & .. i ::;■:: ':;'■::,; .......,....$74.95 4 5 Uigii w Frequency Capacitance and Data Hold Switch $99,95 ■ Programs all currenl EPROMs in the 271 6 to 37512 range plus the XZB64 EEPROM • RS232 port • Sollware included EPP $199.95 UVP EPROM Eraser • Erases all EPROIWs ■ Erases 1 chip 15 minutes and 8 chips in 21 min ■ UV intensity: 6800 UW.'CM 2 DE4. .$89 EPROMs - for your programming needs Part No. Price Part No. J AMECO g 24 Hour Order Hotline o EC (415)592-8097 o LU —I Lit o Q < rr 92 WS4 MMC <£&> Please reler lo Mail Key 2 when ordermrj Handheld Multimeter ■ 3 5 digil LCD with autc-matfc polarity indication * AC- DC voltage measurement up to 500 wjlls " AC DC currenl measurement up to 200mA * Resistance measurement op to 2QMii - Con- tinuity checker with audible tone * Diode and logic tester « Au to manual range and dala hold functions « AH range protection and function in- dications DMM905 $39.95 TMS2516 TMS2532-35 TMS2532A TMS2564 TMS2716 1702A 2708 2716 2716-1 27C16 2732 2732A-20 2732A-25 2732A-45 27C32 $4.25 9.95 7.95 5.95 5.95 3.95 4.95 3.49 3,95 4.25 4.95 4.95 3.49 2.95 4.95 2764-20 2764-25 2764-45 2764A-20 2764A-25 27C64-15 27C64-25 271280TP 27128-20 27128-25 27128A-15 27128A-20 27128A-25 27C128-15 27C1 28-25 Price Part No. 1 $3.95 272560TP $ 3.75 27256-15 3.49 27256-20 3.95 27256-25 3.25 27C256-15 3.95 27C256-20 3.25 27C256-25 2.95 2751 20TP 6.95 27512-20 7.95 2751 2-25 5.95 27C512-15 4.49 27C512-20 3.75 27C512-25 5.95 27C010-15 1 7,95 68766-35 Partial Listing ■ Over 4000 Electronic and Computer Components in Stock! CIRCLE 114 ON FREE INFORMATION CARD Competitive Prices Computer Products and Electronic Components Assemble Your own Computer Kit! Jameco 16MHz 80386SX Desktop Computer Kit > Building your own computer provides you with a better understanding of components and their to notions 1 In-depth assembly instructions included Have your new computer assembled and running in an evening, using common tools Soltware included Purchase computer kits configured by Jameco or design your own J AMECO ^^ ELECTRONIC COMPONENTS COMPUTER PRODUCTS 24 Hour Order Hotline (41 5) 592-8097 * 7 nf Jameco 16MHz 80386SX Desktop Computer Kit Includes: ■ 80386SX Motherboard with 2MB RAM (expandable to 8MB) ■ 101 -key enhanced keyboard -Multi I/O Card • Toshiba 1 ,44MB, 3.5" DSHD floppy disk drive • Baby sized desktop case • 200 Watt power supply • DR DOS 5,0 by Digital Research and AMI diagnostic software Relisys14" VGA Color Monitor • Max resolution: 720 x 480 ■ Bandwidth: 30MHz * Input: D815-pin (analog) RE9513 $399.95 Jameco 16-bit Super VGA Card ■ Emulates VGA. EGA. CGA, MDA and Hercules modes ■ Comes with 512K8 video RAM upgradable to 1MB (Four 514256-801 ■ Capable ol 1024 x 763 with 256 colors (1MB video RAM lequiredl JE1058S $229,95 Integrated Circuits Part No. 1-9 10+ Part No. 1-9 10+ 7400 S.29 S.19 7472 $1.95 S1.75 7402 .29 .19 7473 .45 .35 7404 ,29 .19 7474 .39 .29 7405 ,35 .25 7475 .49 .39 7406 .39 .29 7476 .45 .35 7407 .39 .29 7483 .69 .59 740B .35 .25 7486 .45 .35 7410 .29 .19 7489 2.95 2.75 7411 .35 .25 7490 .49 .39 7414 .35 .25 7493 .45 .35 7417 .35 .25 74116 1.19 1.09 7420 .29 .19 74121 .49 .39 7427 .35 ,25 74123 .49 .39 7430 .35 ,25 74125 .49 .39 7432 .39 .29 74151 .39 .29 7438 .45 .35 74160 .59 .49 7442 .49 .39 74161 .69 .59 7445 .75 ,65 74192 .79 .69 7446 .89 .79 74193 .79 .69 7447 .89 ,79 74194 1.19 1.09 Miscellaneous Components Potentiometers Values available (insert ohms into space marked "XX"): 500U. 1K.5K. 10K,20K.50K, 100K, 1MEG 43PXX *n Watt, 15 Turn $.99 63PXX 'p Watt, 1 Turn $.89 Transistors And Diodes PN2222 $.12 1N4735 $.25;2N4401 $.15 PN2907. 12 2N3904 12J1N4148 07 1N4004 10 1N751 15J2N3055 69 2N2222A 25 C106B1 59HN270 25 Switches JMT1 23 SPDT, On-On (Toggle) $1 .25 206-8 SPST. 16 pin (DIP) - $109 MPC121 SPDT.OnOtfOi (Toggle) $1 .19 MS102 SPST. Momentary (Push-Bulton) $.39 D-Sub Connectors and Hoods DB25P Male. 25-pin $.65|DB25H Hood $.39 DB25S Female. 25-pin... $.75 1 Hard Drives Conner (16-bit IDE) C P3044 40MB 3.5' Low Pintle $339.95 CP3184 60MB35-HH... .$599.95 CP3104 100MB 3i"HH ,.....$649.95 ADP20 Hosl Adapter $29.95 Look to Jameco • Wide selection of integrated circuits and components ■ Quality prototype and test equipment ■ Computer kits and accessories Additional items that Jameco offers: Tools Cables Connectors Data Books Motherboards Memory Math Coprocessors Computer Accessories Power Protection Equipment Much, much more ! Let us show you what we have to offer; call or write lor the latest Jameco catalog! 4164-100 4164-120 4164-150 41256-60 41256-80 Dynamic RAMs 100ns. WK n $1.95 41256-100 1.89 1.99 2.75 2.49 XC209R Ti XC556GT1 LEDs (Red) $.14 XC556R 4. (Green! ...16 XC556Y IC Sockets T1 3 .' (Red) ...$.12 , (Yellow)... 16 $50.00 Minimum Order Data Sheets - 50c each Call lor a FREE So.page catalog 1 . B 1991 Jameco Electronics 9J91 CA Residents Add 6.00%. 6.50% or 7.00% Sales Tax Shipping, handling and insurance are additional. (Costs may vary accofdi ng to wsipiis and shipping nuecnoc I Terms: Prices subieci to change without notice. Items subject to availability and prior sate. CompSele Irs! pi lerms wainnsiin is available upon readiest IBM * ■ ng41eraa FM«nu> or ^r«4«tui«tfc" Buiiitftti Matmr*! J AMECO ^^ ELECTRONIC COMPONENTS COMPUTER PRODUCTS FAX: (415) 592-2503 (415) 595-2664 1355 Shoreway Road Belmont, CA 94002 ■ Customer Service -Technical Assistance • Credit Department ■ AH Other Inquiries ■ (41 5) 592-8097 • 7AM - 4PM P.S.T, CIRCLE 114 ON FREE INFORMATION CARD 120ns. S4K I 1 150ns. WK t 1 Mliis. 2SSK x 1 SUns. 255K 1 1 100ns. 256Kii $1.99 41256-120 120ns. 2S6K n 1.89 41256-150 i50n 5 256Kst 511000P-8DBfjns. 1MB it 511000P-10 toons. 1MB m 1.85 7.95 6.95 • Call tor a complete listing ot IC's Low Profile 8LP 14LP 16LP 24LP 2BLP. 40LP Wire Wrap (Gold) Level #2 8WW $.49 14 WW 69 16WW 79 24WW 1.15 2BWW 1.39 40WW 1.89 Soldertail Standard & Header Plug Sockets Also Available .$.11 ...12 ...13 ...19 ... .22 ... .28 93 LWICORN ELECTRONICS 10010 Canoga Ave., Unit B-8 Chatsworth. CA 91311 SINCE 1983 — YOUR I.C. SOURCE — AND MUCH MORE!! NO SHIPPING CHARGES ON PRE-PAID ORDERS!* NO CREDIT CARD SURCHARGE! SCHOOL P.O.'s WELCOME! LASER DIODES Dynamic RAMS EPROMS STOCK * MFG LS9220 TOSHIBA LS9200 TOSHIBA LS9201 TOSHIBA LS9211 TOSHIBA LS9215 TOSHIBA LS320D NEC LS022 SHARP WAVE- LENGTH 660 nm 670 nm 670 nm 670 nm 670 nm 670 nm 780 nm OUTPUT OPER. POWER CURR. OPEH. PHICE VOLT. 3mW 3mW 5mW 5mW 10 mW 3mW SmW 85 mA BSmA 613 mA SO mA IS mA 85 mA 65 mA 2.5V 2.3V 2.4v 2.3* 2.4* 2.2V 1.75V 129.99 49.99 59.99 69.99 109.99 79.99 19.99 LASER TUBES STOCK* 41256-60 412S6-S0 41256-100 41256-120 41256-150 511000-70 511000-80 511DOO-10 514256-70 5 14256-80 514256-10 541000-80 544256-80 DESC. 256K.S 1 256KI1 266K x 1 256K i 1 256K J 1 1 meg x 1 1 meg x 1 1 meg x 1 256K * 4 256K i 4 256K i 4 4 meg x 1 1 iriL-t; x 4 SPEED 60 ns 60 ns 100 ns 1 20 ns 150 ns 70 ns 80 ns 100 ns 70 ns 80 ni 100 ns 80 ns 8o m 1-24 2-59 2.19 1.99 1.89 1.79 5.49 5.29 5.09 6.49 6.09 5.89 26.99 31.99 25-99 2.46 2.0S 1.89 1.80 1.70 5.22 5.05 4.64 6.17 S.79 5.41 25.64 30.39 100+ 2.21 1.87 1.70 1.62 1.53 4,70 4.53 4.36 5.55 5.21 4.67 23.08 27.35 STOCK* 2716 2732 2732A 2764 2764A 27128 27C128 27256 27C256 27S12 27C512 27C1024 27 C 204 8 SPEED 450 ns 450 ns 250 ns 250 ns 250 ns 250 ns 250 ns 250 ns 250 ns 250 ns 250 ns 200 ns 200 ns 1-24 25-99 3.29 3.13 4,19 3,29 3.49 3.09 4.79 4.79 4.59 4.29 5.49 5.49 3.98 3.13 3.32 2.94 4.55 4.55 4.36 4.08 5.22 5.22 10.99 10.44 21.99 20.89 100+ 2.82 3,58 292 2.99 2.65 4.10 4.10 3.92 3.67 4.70 4.70 9.40 18.80 STOCK * WAVELENGTH OUTPUT POWER (MIN) OUTPUT BEAM POWER DIAM. (MAX.) BEAM OIVERG. POLARI- OPERATING OPER. FIRING ZATION VOLTAGE CURR. VOLT. LT7770 LT7650 LT7556 LT7655 LT7655S LT7632 LT7621S LT7634 LT7621MM LT7627 LT7628 LT7627MM 543 nm (Green) 632 .flnm (Red) 532 .Bnm (Red J 632.Snm (Red) 632.Snm (Red) 632.8nm (Red) 632.8nm (Red) 632.8nm (Red) 632.8nm (Red) 632.8nm (Red) 632.8nm (Red) 632-Snm (Red) O.SmW 0.5 mW O.SmW 0.5 mW 1.0mW IjmW 2.0mW 2.0mW 5,0mW S.OmW S.omW 10mW 1.0m W 2.0mW 2,0mW 2.0mW 2,0mW 30mW S.OmW S.OmW 15mW 15mW ISmW 30mW 071mm 0.49 mm 0.34 mm 0.49mm 0.49mm 0.61mm 0.75mm 0.75mm 1.0mm 0.80mm 0.80mm 1.2 mm i 1.2 mrad £ 1.7 mrad < 2.4 mrad S 1.7 mrad £ 1.7 mrad < 3.0 mrad £ 1.2 mrad < 1 .2 mrad £ 2.5 mrad < 1 1 mrad £ 1.1 mrad < 4.0 mrad random >!00:1 random random random random random >500:1 random random >500 1 random •75Du: lOOOv- i050v: lOOOv^ lOOOv^ 1300^ : 1300^: 1250*: I900v; 1900*: 17S0v: 110v 100V 100v 100V 100k IOOv 100v IOOv 100v IOOv 100v IOOv 6.SmA 3.5 mA 2.8 mA 3.5 mA 3,5 mA 3.5 mA 5.0 mA 5.0 mA 6.5 mA 6.5 mA 6,5 mA 6.5 mA < 8kV < 7kV < 8kV £ 7kV < 7kV £ 7kV < 7 kV £ 7kV £ 7 KV < SkV < 8kV <, :-: ■■:■; MIN. SERIES RES. 81k a 68k n 82k n 68k 68k n Bikn 68k n E8k n 68k n Blk n ■?,■: n sik n SIZE WT. DXL (GM.( (IN MM) 37x350 25x146 22.5 x 1 18 25 X 150 25x150 20x210 30x255 30x255 30x255 37x350 37x350 37 x 350 200 70 80 70 ,'!.: 70 140 140 140 200 200 200 BRH CL. II Ilia Ilia Ilia life Ilia Ilia Ilia 1: 13 lllb lilb lllb PRICE 1-9 799.99 529.99 134.99 144.99 159.99 249.99 204.99 209.99 359.99 369.99 389.99 479.99 749.99 479.99 124.99 134 99 144.99 229.99 191.99 194.99 334.99 344.99 384.99 444.99 Laser Pointer • Output: 3,5 mW • Wavelength: 670NM ■ Power Supply: 2xAAA Batteries (included) ■ Beam: Appro*. 3" @ 100 yards Quantity Discounts Available STOCK # PRICE LSPOiNT $199.99 Power Supply ♦" Input: 11 5/230 V . Output: +5v @ 3.75A +12v@ 1.5A -12v@ .4A ■ Size: 7" L x 5V," W x 2W H STOCK » PS1003 PRICE S19.99 Collimator Pen ■ Output: 2.5 mW (max.) • Current: 90-150 mA • Op. Volt.: 2.2-2. 5V ■ Wavelength: 820NM ■ Data Sheet inc. STOCK # SB 1052 PRICE $39.99 Disc Drive & Computer Cleaning Kit Nol just a drive cleaner-but a complete computer cleaning kit. includes sv*abs, head cleaning fluid, anti-static cleaner, screen wipes and cleaning di Skene. STOCK # PRICE SB1099 3Vs" Kit $6.99 SB1100 5VV Kit $6.99 Disc Drive Head- Cleaning Kit c _ Anti-Static Screen Wipes Robotic Arm Kit Avoider Robot Kit Includes cleaning fluid and head-cleaning diskette STOCK # PRICE SB 1105 3Vs" Drive Kit $1.99 SB1106 5V." Drive Kit $1.99 For static-sensitive app&jcalions. Dispenser packs, individually wrapped. STOCKS PRICE S81104 Dispenser pack S1.99 of 25 wipes $61107 Dispenser pack $4.99 of 100 wipes Robots were unco ccmlined to science taction movi» Today. whetlwlhe^Ve performing cangerotis tasks or putting together complex products robolics are iindtng their way nto more and more industries. The Robotic Arm K'E is an educational hit that teaches basic robot.c arm fundamentals as well as tasting your awn molar skills. Command n 10 periorm simple tasks s% An intelligent robot (hat knows how io avoid hitting walls This robot emits an infra-red beam which delects an obstacle in front and then automatically turns ieft and continues on. STOCK # Y01 PRICE $49.99 STOCK # MV912 PRICE $49.99 o o BE b LU 6 Q ORDER LINE — (800) 824-3432 INTERNATIONAL ORDERS — (818) 341-8833 FAX ORDERS — (818) 998-7975 6 TECHNICAL SUPPORT — (818) 341-8833 CIRCLE 185 ON FREE INFORMATION CARD • 15.00 MINIMUM ORDER • UPS BLUE. RED & FEDERAL EXPRESS SHIPPING AVAILABLE • OPEN MON-FRI 9:00 AM - 6:00 PM. SAT 1 0:00 AH - 3:00 PM POT • CA RESIDENTS ADD 7°, SALES TAX • CALL FOR QUANTITY DISCOUNTS • CALL FOR FREE CATALOG (FOR 1ST CLASS DELIVERY OR CATALOGS DELIVERED OUTSIDE THE U.S. — SEND $2.00) • WE CARRY A COMPLETE LINE OF ELECTRONIC COMPONENTS ■NO SHIPPING CHARGES ON PRE-PAID ORDERS DELIVERED IN THE CONTINENTAL U.S. 94 FAX DIRECT 1-800-582-1255 WCH ORDER DIRECT 1-800-582-4044 j VHF - UHF RF TRANSISTORS" ~] Output Input Frequency Gain Or der # Price Pwr. (W) Pwr. (W} Range (Mhz) db.' Mhz 'Packaga MRF221 MRF237 MRF238 MRF240 MRF240A MHF247 MRF260 MRF262 MHF317 MRF321 MHF340 MRF401 MRF406 MRF422 MRF426 MRF427 MRF428 MRF450A MRF455A MRF45B MRF51S MRF555 MRF559 MRF607 MRF641 MRF646 MRF6S2 MRF654 MRF660 2N3866 2N4427 2NS641 2N5642 2NSS43 2N5944 2N5945 2N5946 2N6080 2N60S1 2N60B2 2N6083 16.35 3.69 15.95 17.49 17.49 24.75 11.95 12.95 64.95 24.95 9.95 13.49 14.99 35.95 19.49 16.95 59.95 14.49 12.69 19.95 2.95 3.49 2.25 2.49 20.49 25.95 11.49 19.95 13.95 1.25 1.25 16.95 18.49 19.95 11.95 11.95 14.95 9.89 11.95 14.95 14.95 15 3.5 136-174 6.3/175 211-07 4 0.25 136-174 12/175 79-05 30 3.7 136-174 9/175 145A-09 40 5 136-174 9/175 145A-09 40 5 1 36-1 74 9/175 21 1-07 75 15 136-174 7/175 316-01 5 0.5 1 36-174 1 0/175 221 A-04 15 3.5 136-174 6.3/175 221 A-04 100 12.5 30-200 9/150 316-01 10 0.62 100-500 12/400 244-04 8 0.4 30-200 1 3/136 221 A-04 25 (PEP/CW).. 1,25 2-30 13/30 145A-09 20 [PEP/CW).. 1.25 2-30 12/30 211-07 150 (PEP/CW) ...15 2-30 10/30. 211-11 25 (PEP/CW) ..0,1 6 2-30 22/30 21 1 -07 25 (PEP/CW) .-0.4 2-30 18/30 21 1 -1 1 150 (PEP/CW) ..7.5 2-30 13/30 211-11 50 4 14-30 1 1/30 145A-09 60 .3 14-30 13/30 1 45A-09 80 5 14-30 12/30 21 1-11 0.75 0.12 400-512 8/470 79-04 1.5 0.15 400-512 10/470 317D-02 0.5 0.08 806-960 8/870 317-01 1.75 0,12 136-174 11.5/175 79-04 15 2,5 400-512 7.8/470 316-01 40 13.3 400-512 4.8/470 316-01 5 0,5 400-512 10/512 244-04 15 2.5,. 400-512 7.8/470 244-04 7 2 400-512 5.4/470 221 A-04 1 0,1 100-400 10/400 79-04 1 0.1 136-174 10/175 ....79-04 7 1 30-200 .......8.4/175 144B-05 20 .....3 30-200 8.2/175 145A-09 40 6.9 ............30-200 7.6/175 ...145A-09 2 0.25 400-512 S/470 244-04 4 0.64 400-512 8/470 244-04 10 2.5 400-512 6/470 244-04 4 0,25 136-174 12/175 145A-09 15 3,5 136-174 6.3/175 145A-09 25 ...6 136-174 6.2/175 145A-09 30 8.1 136-174 5.7/175 145A-09 "Complete dimensions, pin-outs and pictures of all packages are contained in Motorola's RF Device Databooks (See Right). Order # Price Description Pins 5719 8362R8 8364R7 8372A 8520A 315093-02 17.95 39.95 37.95 99.95 16.95 34.95 Gary [8386) 48 Denise "Half Bright" (252126-02) 43 Paula (2521 27-02) 48 Farter Agnus (1MB) For A50Q/A20Q0 (318069-02) PLCC 84 Complex Interface Adapler For ASOO/AUDOO (318029-03) 48 KickstartROM1.3 40 'NOTE: No data available on Amiga computer chips ■Dimensions: 1.187" s .95" >: .735" ■Cross To: P&B' R1 series -Mounting: Solder terminals 'P&B p Poller & Brumfleld Order # 1-9 10+ Description Coll Res. R185-3 R185-7 6.99 5.99 7,99 6.99 Relay 1 2Vdc Relay 12Vdc .18511 .1B5S2 Contact patina Contact 3A DPTD 7.5A DPTD CH.22 .89 CH.39 .89 CH.32 .89 CH1.0 .89 CH2.2 1.09 CH4.7 1.09 CH6.8 1.49 CH10 1.49 CH22 1.49 .79.. .79.. .79.. .79.. .99.. .99. 1.39.. 1.39. 1.39. Freq. Resist. (DC) Indue! 0.1 4C1 935mA 0.3CS1 640mA ...0.22 .0.39 ...0.82 25Mt« 0.8511 380mA ...1.00 25Mhz I.0DS 350mA ...2.20 7 9Mhi 0.4011 550mA ...4.70 7.9Mhz 1.2011..... 320mA ...6.80 7.9Mhz.. 2,000. 245mA 10 7.9Mhz 3.7015. 180mA 22 2.5Mhz 3.30U 190mA 1.49 1.39 47 2.5Mnz 4S0n 165mA miMMWMtiMteMi RF Device Data - Volumes 1 & 2 This rwo volume set contains over 2200 pages of dala on RF Power TWOS FETs, RF Power Bipolar Transistors, RF Small Signal Transistors, Tuning and Switching Diodes, and RF Amplifiers, Also included are drawings, diagrams, dimensions and pin-outs on all packages. Order jf DL1 10 1 4.95 RF Device Vol. 1 & 2 Weight: 4.25 lbs. Telecommunications Device Data Almost 900 pages covering Switching, Integrated Voice/Data, Modem. Filter. Dala Communication, Basic Phone. Cordless Phone, Transmission and RF Modem Circuits, Order#DL136 11.95 Telecommunications Device Data Weight: 1.75 lbs. MPU/MCU/Peripharal Data - Volumes 1 & 2 Over 2300 pages on Motorola's Microcontroller and Microprocessor families such as the MC6300. MC6802, MC6S21, MC6846, MC146813. MC68701, MC68705, etc. Order # DL139 16.95 MPU/MCU/Peripheral Data- Vol. 1 & 2 Weight: 4 lbs. CK MOUNT CABIN A range ol ventilated 19" rack mount cabinets, designed to accept DIN 41494, IEC 297. EIA RS-310 C-1977 and JIS C601 0-1969 Classic and contemporary styling, black hi-gloss finish, together with innovative techniques result in a ruggedly built stylish enclosure. The cases are supplied flat packed and are easy to assemble. Order* 1-9 10+ Panel (mm'in) E3120E E3120C Cabinet (HxWxD mm/In) Handle Weight E3120A 36.95 34.95 4S0i19.2'*«'1.7r 38'1.5-*«J/16.7"lZ44r9.S- - 6.5 lbs. E3120B 44.96 42.95 4Srj,'19.2 - x B7/3.4S - B3/3.3Z - x 424/1 6.7" x £44*3.6* 67/2.68".. 7.7 lbs. E3120C 49.95 47.95 4B0,'19.2" ■ B7/3.4S- .S3V3.32" J 424/16.7-* Wa'13.32" ....57S.W 9.02 lbs. E3120D 54.95 52.95 480/t9.2" x )32/5.ZS"..,122/4.Ba" I 424,'IS.r I424/I6.r..-..9S73.92' 10.12 lbs E3120E 59.95 57.95 460.192" x 177.708" 172^Bfl" x 424/16 7"x333/13.32"„..13& ! 5.44",...10.7S It 3TEEL ENCLO FEATURES ♦Ventilation holes ■Self-adhesive feet included -From 5 rear panels: 1.3 mm aluminum alodine (painted white) ■Top & bottom covers: 0.9 mm phosphated sleet (painted black: Order # 1-9 10+ Pes or i pt ion Pi me ns to ns (Hx Wx D ) E3119A 12.95 11.95 E3119B 15.95 14.95 E3119F 19.95 18.95 E3119G 13.95 12.95 E3119K 24.95 23.95 E3119P 29.95 28,95 Steel Enclosure 2.5"x8" x 7" 2. 64 lbs. Steel Enclosure 2.5" x 12" x 7" 3.74 lbs. Steel Enclosure 2.5" x 1 7" x 1 1" 6.82 lbs. Steel Enclosure 3.5" x 8" x 7" 2.86 lbs. Steel Enclosure 3.5" x 17" x 11" 7.26 lbs. Steel Enclosure 5.2" x 17" x 11" 7.70 lbs. E >yiech 2917 Bayview Drive Fremont, CA 94538 Order Direct: 1 Fax Direct: 1 ■800-582-4044 800-582-1255 Monday- Friday, 7am - 5pm (PST)/10am-8pm (EST) _VJ COD-No personal checks, US funds ($5.00 Charge) ED USPS V ups V Federal Express IV I Airborne Add 5% of total for shipping UPS Ground ($3,00 min.). Actual shipping charges based on weight. Call or write today for your free copy of our 1 991 catalog. California residents, add appropriate sales tax. 12 month warranty on all EasyTech products. 30 day money back guarantee. We reserve the right to substitute manufacturers. Prices subject to change without notice. CIRCLE 181 ON FREE INFORMATION CARD W m TJ -I m oo m 3] 95 SCIENTIFIC & ELECTRONIC PRODUCTS LASERS AND SCIENTIFIC DEVICES VRL2K 3mw His Red Laser Diode System Kit 5159.50 LUSH Lassr Beam "B tunica" 1 Listener Kit S19S.50 LHUK Visiule Simulated 3 Color laser Kit J44.50 LC7 40 Will Burning Cutting Laser Plant S2Q.au RUB4 Hi Powered Pulsed Drilling Laser Plana S20.00 LGU4Q I |D2mWHeWi Vis Red LaserGun Assembled ........5199-00 LLS1 LiserLiteSlio«r-3 Methods Plans SZO.llu SD5K See in the Dark Kit S299.50 EML1K Elecliomeanetic CDil Oun Kit S59.S0 MCPI Hi Velocity Coil Gun Plans SIS. 00 LEVI LeYllalino Deiriee Plana Sia 00 EH1 Electronic Hypnotism TeohniQues Plans $10. DO HIGH VOLTAGE AND PLASMA DISPLAY DEVICES HVM7K 75.000 Volt DC Variable Output Lab Source Hit $149.50 I OG3K I o I i R ay G i . i K il . 1 1 ru : a cl g n g ■■ y j .',' . i h : u I ■:: re s $69.50 NIG9K 12V.-115 VAC Hi Out Neg Inn Generator Kit $34.50 ErVtAlK ft I ikinel c i-nl'i n. ;■ I l.:::ln:: Man AssemBler) $99.50 LG5K Lightning DisplayGlobeHIt S54.50 BTC1K Worlds Smallest Tesla Coil Kit S49.50 BTC3K 250KU Table Top ftsla Coil sit SZ49.50 BTCS 1.5 Million Yells Tesla Coil Plans SZO.OO JL3 Jacahs Ladder -3 Models Plans $15.00 GP.A1 Anil Gravity Generator Plans $10.00. PFS20 Plasma Fire Sailer Assembled $59.50 DPL20 Dancing Plasma la Music and Sounds Assembled $79.50 SECURITY AND PROTECTION DEVICES I TM 1 1 DO .00 Vo II I nil midalo r up 1 19" Assembled $129.50 IPGTD Invisible Pain Field Blast Wave Gen Assembled $74.50 PSP4K Phaser Sanic Blast Wave Pistol Kit $59 .51) LIST10 Infinity fcntr, lislen in Via Phone Assembled $199.50 TAT30 Automatic Tel Recording Oevice Assembled $24.50 VWPM7K 3 Ml. FM AuloTel Transmilter Kit $49 .50 FMV1K 3M1.FM Voice Trans miller Kit $39.50 HQD1K Homing/Tracking Beeper Transmitter Kil..... ...$49.50 EAST OflOEHIHB PBOCEOUBE TOLL FBEE 1-SOO-22M705 or 21 UBS OM t -603-673 -4730 or FM IT T0 1 -SOS -672-54(16 VISA, 'rlt: CHECK. MO IN OS FUNDS. INCLUDE 10% SHIPPING. DROERS SIM JJ S UP ONLY ADD $10 00. CATALOG SI. 10 OR FREE WITH OB DEB. INFORMATION UNLIMITED P.O. BOX 716, DEPT. R3, AMHERST, NH 03031 ADVERTISING INDEX THE ELECTRONIC GOLDMINE C/3 o o o < LT 96 Th* Electronic GoHmk™* has one rJ Ihe J QfEfllESt KlKlJDIB Dl UriOJLB escclronic kits avatfafcte in ihe ftOfM! iVe hM Oter 65 kils and met 1.400 unique, bargaiii priced, ramponana ■r OH Ci: jli.fi 1 -AT^LObr IttPF ERtWT ! liVAC ADAPTER ftttJ CU 1?5VAC X. up ki 265 rru. Brand ntW. ftU imrf 2 (Wig (OTHlf txrwdzr grU lovj riwaij wftt. fa lUndaiTj 120 VAC G95D 11.39 .«12 10CVS1CB \j%® FISH CALLER KTT Thic Vt prodLjcB* ■ ekekhg isund when It uid to jfluct Ish Wi hm had axlaron *tu rw« reported exzolcrt Is' FijjJiitis very Cny Crtul bt-i'G jTKl ^Tijl Glycol KiSni a'lmati v/vJ' ■r.cn ::a plaCOCl it a WolW "•.)"" 0' arc) ■TrWed ri:- IThB wattr. OpfifauM Iram a ■3V L-:.:iorv («* nciJd&d) C4S6Q W5D METAL LOCATOR KIT TCT1 ■)!'■' Oaioct corn, mga, burwd Inctaitjr*, Ate wffi nil iirpki >c buld > i. Trin- »lCriZKl EXCUt UHH UnrqLKI (JPiWiiClfi col, irrhtdhl if wand OTOCSf/ fje Top rjl PC b«nl 1r>« Mdn] I . cx-j fcr Ki1 rtolocrs moljl win A shi*1 in t«H whctl q. iriBmfjd b a sLarWlafd pOftlHa AM ridia i'ioj sjL^ryl Optxaloi iron a 9V biLBv (ra ndiritxll C4515 $5-^S MICRO MINI HIGH VOLTAGE POWER SUPPLY 9? 'Bit "_7T aflt in' 1GQW vrih ortrV Ci.'OC 4". L>awi orty (£ G99t S6.00 INVERTER TRANSFORMER ^rrrn i -t rj^ij ! - ii"-i'::"r»}i ItH lt» win 555 C r. i-y-,tn 12VDC to 250/ In itrobttf hjor«Kvt Tdbos wKh tchtmalac. N17G3 £:.lO uch TINT RECTANGULAR SPEAKER TT« lit, | '" **fJ cpMkhdr « M raafirtw l a^ riCDchn -JL-t (Ticedareti and r.i/^ ic«jjf4> Trta! cast Gr-w" fcr JTlrnirtUtC np^Kalorn Sao w* si/ie,- * aw G9SS *1-0Q ioa$aa ULTRAVIOLET SENSOR SUN EXFOSURS METER — ^MM^ Snu'I oriicttTcot; dwn dalccl? 1jV (n*rm f"?" 1 Tv 5LT^ and SWxIs Jl sy-ii wCnn yCm'vd hM nrlcLfijIi Bjt(JHCrni. H«5 2 il^i ror skin Ira grid sun scrrHn rung (SPP, UloS ,C craiiiy irJ ipsciai ijv »nsa. AsiwdilflfJ and wattf o utw, nc now cuipLs (am ri naw av&lafSti at a Sradion cf Ha ongnal com (BefiiftM W bflti«Y. kA ndudacr 1 i-^** u q* MINIMUM OHDEH: $10 00 p!u£ $3Su sfupping and ?unc!-ng Wet accept MO. Vgj and Money OnJerS- SEfJD ORDERS TO. TlTt? i' .:■!■■■< .. .'iOtUTWie P.O. Box 5408 ScoHKtiie. AZ 85261 PHONE ORDERS (&Q2) 4&1'74$4 FAX ORDERS (602} 451-9495 CIRCLE 182 ON FREE INFORMATION CARD RADIO-ELECTRONICS does not assume any responsibility for errors that may appear in the Index below. Free Information Number Page 108 AMC Sales 39 75 Ace Products 30 107 All Electronics 93 — Amazing Concepts 88, 96 180 American Reliance Inc 30 84 Appliance Service 30 109 C&SSales 32 — CIE , 7, 29 — Cable Ready Company 84 — Command Productions 75 — Computer Book Club 73 58 Cook's Institute 39 127 Deco Industries 30 181 EasyTech 95 182 Electronic Goldmine 96 — Electronics Book Club 8 121 Fluke Manufacturing CV2 — Fordham 3 — Global Cable Network 83 190 Cilobal Specialties 5 — Grantham College 25 86 Heathkit 14 189 Hewlett Packard 15 — HighText Publications, Inc 72 — ISCET 87 1 14 Jameco 92 87 MCM Electronics... 85 53 MD Electronics 86 93 Mark V. Electronics 87 1 17 Mouser 24 — NRI Schools 21,81 186 Optoelectronics CV3 56 Parts Express 89 — Perfect Cable 84 177 R.L. Drake Co 31 78 Radio Shack 23 187 SCO Electronics 78 — Scope Electronics 3 176 Sencore CV4 — Star Circuits 24 92 Tektronix 13 123 Test Probes 17 — The SPEC-COM Journal 39 185 Unicorn 94 188 US Cable 78 178,179 Viejo Publications 72, 75 184 WFI' Publications 77 191 Worldwide Cable 88 ADVERTISING SALES OFFICE Gems back Publications, Inc. 500 B Bi-County Blvd. Farmingdals. NY 11735 1-C516) 293-3000 President: Larry Steckler For Advertising ONLY 516-203-3000 Fax 1-516-293-3115 Larry Steckler publisher Christina Estrada assistant to the President Arline Fish man advertising director Denise Haven advertising assistant Kelly McQuade credit manager Subscriber Customer Service 1-800-288-0652 Order Entry for New Subscribers 1-80O-999-7139 7:1X1 AM ■ 6:00 PM M-F MST SALES OFFICES EAST/SOUTHEAST Stanley Levttan, Eastern Sales Manager Radio-Electronics 1 Overlook Ave. Great Neck, NY 11021 1-516-487-9357, 1-516-293-3000 Fa* 1-516-487-8402 MIDWEST/Texas/Arkansas/Okla. Ralph Bergen, Midwest Sales Manager Radio-Electronics 540 Frontage Road — Suite 204 Northtield. IL 60093 1-708-446-1444 Fax 1-708-559-0562 PACIFIC COAST/Mountain States Marvin Green, Pacific Sales Manager Radio-Electronics 5430 Van Nuys Blvd. Suite 316 Van Nuys. CA 91401 1-81 B- 986- 2 001 Fax 1-818-986-2009 RE Shopper Joe Shore, National Representative P.O. Box 169 Idyllwild, CA 92349 1-714-659-9743 Fax 1-714-659-2469 MAXIMIZED SENSITIVI U We've Carefully balanced the amount of gain used in our input amplifiers - too much or too little results in poor performance. m OPTOELECTRONICS 1 HANDI-COUNTERS ' with maximized V^ sensitivity give you the maximum range for antenna pick-up. Made in the USA MODEL 3000 Multi-function Counter 10Hz-3GHz, 1 Digit LCD with frequency, period, ratio, interval & signal level bargraph....$375. Maximum Security Device. Increase your frequency finding™ by 10 times the distance or more. Tunable Preselector APS-104 $995. Counter Sold separately MODEL 8030 With all the features of the 3000 plus enhanced input signal conditioning and enhanced TCXO time base $579. S 199 The Original Pocket-Sized LED Handi-Counter™ All of OPTOELECTRONICS' LED Handi-Counters™ will: • Count frequencies above 2.4GHz. Have display saving Power Switch (avoids premature LED burn-out, leading cause of counter failure.) Accept no substitutes - Look for the OPTOELECTRONICS name on the label! J Model 2300- 1MHz-2.4GHzl Available with NiCads and AC Charger Adapter. Complete Package only.. ..$128. Only OPTOELECTRONICS offers you MAXIMIZED SENSITIVITY. 1-800-327-5912 Model 221 0A 10Hz-2.4GHz Full range counter. Price includes Nicads & AC charger/adapter. Factory Direct Order Line FL{305)771 -2050 ' FAX(305)771 -2052 5821 NE 14th Ave. • Ft. Lauderdale, FL33334 ■ 5% Ship/Handling (Max. $10) U.S. & Canada. 15% outside continental U.S.A. Visa and Master Card accepted CIRCLE 186 ON FREE INFORMATION CARD Introducing The Only Complete Solution For All Your Monitor Servicing Needs! CM2000 Computer MonitorAfll The Only Analyzer That Helps You Pinpoint Defects In All Computer Monitors! Patented - A Sencore Exclusive! Completely Test And Troubleshoot All High Resolution And MuIti-Scai Computer Monitors From The Input Connector To The CRT... Guaranteed! Here's What The CM200Q Offers You: • Complete High Resolution Computer Monitor Analyzing • Fully Programmable Scan Rate And Pixel Resolution • Innovative Performance Testing Patterns • Special Sync-Locked Substitution Signals • Patented "Ringer" Test To Dynamically Analyze All: • Yokes • IHVTs/Flybacks • Switching Transformers ■ Integrated 2,000 DCV And P-P Meter ■ Exclusive "Hook-up" Adapters Available For All Popular Monitors • Portable Troubleshooting For All Your Field Service Needs Call 1-800-SENCORE «t 70S (736-2673 circle i?s on free information card 3200 Sencore Drive, Sioux Falls, South Dakota 57107