DSP: THE NEW BUZZ WORD IN CONSUMER ELECTRONICS [K 48783 ECHNOLOGY - VIDEO - STEREO - COMPUTERS - SERVICE UILD THIS 16-CHANNEL, 0-MHZ LOGIC NALYZER \ full-featured stand-alone nalyzer BUILD A SOLID-STATE COMPASS Hall-effect sensors keep you on the right track UEL CELLS i look at the echnology ehind o morrows mergy .ource CONVENTION SYSTEMS >VST1U WAV! HUN HfU> ft E.BC l_J u I I l_| u u ■imp STMC III. O => u LJ M, u u ! — ' 7F CONVERTERS low Voltage-to-frequency converters can provide a ow-cost alternative to \DCs. mm $2.95 U.S. $3.75 CAN GERNSBACK scmsaoc* ChR-RT SORT o: CRD3 75n456HRR5i65MQ93 DG 64 SEP 91 FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT FLUKI PHILIPS High Resolution Digital Meter: TOO count digital readout; 20,000 counl mode (Flute 87) (or 4V» digit resolution Backlil display: Mates it easy to read the DMM in dark, cramped quarters. Automatically shuls off after 68 seconds to save Ihe battery. Analog MBler: High-speed analog display updates 40 times/ second - as last as Ine eye can follow; X10 Zoom bargraph mode (Flute 83 and 65) mates high resolution offset measurements a snap. Recwdarr records minimums and maximums, plus true arilhmEtic average; audible Min Ma* Alert; selectable response times— 1 second and 100 ms [all models) plus 1 ms Peak Min Max (Flute 87) Holster with Flex Stand": Prolects meler and provides test lead storage. Flexible leg allows meler lo be rung from peg, bent around a pipe, or used almost anywhere. FLUKE 83 FLUKE 85 FLUKE 87 Vol Is, rjrims. amps, dicdelesl, audible conlinuily, frequency and dutycydR^ ■;j:Kt:..:'i',<: "_■:'■■:; :j"'i:. live proi-scl ive " r: sl-ar wi I ^- Fi ex-SLar: d "" * 5215' $255" S30Q" C. 3% bas-tdc accuracy G.l^bis'Ei: accuracy cr-aba^cdCKLLra:,' 5*HzreV 20 kHi acV 20kKiitV Analog banrjraph i"4 iZ'Zr Analog bargraph and zoom HighresDivlion araloao^nttM Three year warranty Three year warranty Tnu-imsx; ■**/; iSig it moce Baculii display TfirHyBafwanaiity 'Suggested US liSfTM Frequency counter: Accurals down lo 0.5 Hi; also measures duly cycle Capacitance meter: Autoranglng, with manual ranging at I he touch of a button Meet the meter that brings an entire test bench to your job. The versatile fluke 80 Series do-just-about- everything "Multi" Meter. It offers everything you'd expect from an advanced handheld DMM, plus a lot you'd find only in dedicated instruments Plus Fluke-exclusive features you can't buy any- where else. All built with the most advanced surface mount design and singie-chip ASIC technology for a thinner, tougher, more reli- able package There's a fully annunciated display for clear operation. Duty cycle function High-speed analog indicator. A protective holster with innovative Flex-Stand'" for easy, adaptable operation. Audible Input Alert™ to reduce the risk of damage to the meter, the user, and the unit being tested. Plus the strongest warranty in the business All good reasons to move up to the truly- multi Fluke 80 Series today. You'll find 80 Series DMMs at your Fluke distributor. For immediate off-the-shelf delivery. Call 1-800-44-FLUKE, ext. 33 for the name of your nearest distributor. John Fluke Mfg Co.inc PO Bn 9090 M/S 250C Everett. VYA 9KB6 US (206) 347-5400 CANADA' 416-B90-7600 OTHER COUNTRIES (206) 356-5500 « Cooyngw 1989, 1990 Jam Fluke Mlg Co . Inc. All ugMs reset veil Prices and smtiliatums subject Id dang* wlhoul notice Ad no 00010 FROM THE WORLD LEADER IN DIGITAL MULTIMETERS. CIRCLE 121 ON FREE INFORMATION CARD June 1991 MZiECtrOillCS 31 LOGIC ANALYZER This 16-channel, 50-MHz logic analyzer makes troubleshooting digital circuits a breeze! Gerard Robidoux and Robert Dmitroca 39 BUILD AN ELECTRONIC COMPASS This solid-state compass uses Hall-effect sensors to point you in the right direction. Anthony J. Caristi 49 EXPERIMENTING WITH PC-BASED TEST EQUIPMENT Build a low-cost, PC-based voltage/ resistance/capacitance meter. James J. Barbarello 43 THE NEW WORLD OF DSP Learn about digital signal processing and the impact it will have in the 1990s. Josef Bernard 54 V/F CONVERTERS Voltage-to-frequency converters can be a money-saving alternative to A/D and D/A converters. Harry L. Trietley 61 FUEL CELLS A look at the "energy source of tomorrow?" Ralph Hubscher 6 VIDEO NEWS What's new in this fast- changing field. David Lachenbruch 22 EQUIPMENT REPORTS Fieldpiece HS25 "Stick" DMM 65 HARDWARE HACKER Electronic tuning diodes, and more. Don Lancaster 72 AUDIO UPDATE A distortion primer: Part 1 Larry Klein 74 DRAWING BOARD Let's add an audible indicator to our logic probe. Robert Grossblatt 80 COMPUTER CONNECTIONS Windows watch. Jeff Hoi tz man Vol. 62 No. 6 BUILD AN ELECTRONIC COMPASS wmammmH «w. PAGE 39 PAGE 43 94 Advertising and Sales Offices 94 Advertising Index 8 Ask RE 14 Letters 83 Market Center 28 New Lit 24 New Products 4 What's News c z m ID to o Z o tr K O UJ o o < Anyone who has spent time de- bugging complex digital circuits knows that a logic analyzer is an essential tool for the job. Besides the ability to sample and store the state of many digital signals, a logic analyzer can — as its name sug- gests — perform complex analyses on those signals to determine their timing and state relationships. You can view the acquired data on either a waveform screen or a state screen, and pull-down menus put the controls at your fingertips. Of course, there's a big price to pay for all that convenience; most commer- cial logic analyzers cost well over $1000, Our alternative, is a 16-chan- nel, 50-MHz analyzer that you can build for less than $700. For ail the details, turn to page 31. THE JULY ISSUE GOES ON SALE JUNE 4. BUILD AN ECG Our electrocardiograph can't replace a doctor and a hospital, but it will help you learn about medical instrumentation and interpreting ECG's. BUILD A PROXIMITY SWITCH Detect the presence and absence of metallic objects — it's perfect for actuator circuits! BUILD A COLOR-BAR TEST GENERATOR Test and troubleshoot your video equipment. D/A AND A/D CONVERTERS An in-depth look at the chips that bridge the digital and analog worlds. As a service to readers, RADIO-ELECTRON ECS 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-ELECTRON ICS may relate to or be covered by U.S. 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 attorney. RADIO-ELECTRONICS, (ISSN 0033-7862) June 1991. Published monthly by Gemsback Publications. Inc.. 500-3 Bi-County Boulevard, Farmingdale. NY 11 735 Second-Class Postage paid at Fermfngdale, NY and additional mailing offices. Second-Class mail registration No. R1251 &62B0. authorized at Toronto, Canada. One-year subscription rate U.SA and possessions SI 7.97, Canada 525.65 (includes G.S.T. Canadian Goods and Services Tax Registration No. R1 25166280), all other countries 826.97. All subscription orders payable in U.SA. funds only, via international postal money order or check drawn on a U.S.A. bank. Single copies 52.95. Q 1991 by Gernsback Publications. Inc. All rights reserved. Printed in U.SA. POSTMASTER] Please send address changes to RADIO-ELECTRONICS, Subscription Dept., Box 55115. Boulder. CO ■0321 -SMB. A stamped self-addressed envelope must accompany all submitted manuscripts and/or artwork or photographs if their return is desired should they be rejected. We disclaim any responsibility for the loss or damage of manuscripts and/or artwork or photographs while in our possession or otherwise. Hugo Gamsback (1 BB4- 1 967) found 9r Lurry Stock lor, FHF. GET, editor-in-chief and publisher EDrTOHIAL DEPARTMENT Brian C, Fenton. editor Marc Spiwak. associate editor Kim Ounleavy, assistant technical editor Tori Scaduto, assistant editor Jeffrey K. Holtzman computer editor Robert Grossblatt. circuits editor Larry Klein, audio editor David Laeheribriich contributing editor Don Lancaster contributing editor Richard D. Fitch contributing editor Kathy Teranzi, editorial assistant ART DEPARTMENT Andre Duzant, art director Injae Lee, illustrator Russell C. Truelson, illustrator PRODUCTION DEPARTMENT Ruby M. Yee, production director Janice Box, editorial production Karen S. Brown advertising production Marcella Amoroso prod uetio n ass istant CIRCULATION DEPARTMENT Jacqueline P. Cheeseboro circulation director Wendy Ala oka 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 S 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 94. Radio-Electronics Executive and Administrative Offices 1-516 293 3000. Subscriber Customer Service; 1-800-2880652. Order Entry for New Subscribers: 1- BOO- 999- 7 133, ■© The Audii Bureau ol Circulation AT $299.95, NO OTHER DESIGN WORKSTATION GIVES YOU SO MUCH FOR SO LITTLE. AR07O BOARD BRAND Function Generator ..sine/square/triangle ...plus TTL Large Breadboarding area holds 24 ICS ...2,500 tie points Triple Power Supply ...+5V fixed, plus two variable 5-15V 8 TTL Logic Probe Indicators Audio Speaker Two Digita Pulsers Two BNC Connectors for oscilloscopes and counters Here's PB-503, the total design workstation. It has everything! Instrumentation, including a func- tion generator with continuously variable sine/square/triangle wave forms — plus TTL pulses. Bread- boards with 8 logic probe circuits. And a Triple Power Supply with fixed 5VDC, plus two variable outputs { + 5 to 15VDC and - 5 to 15VDC). Throw-in 8 TTL compatible LED indicators, switches, pulsers, OVER $600 WORTH OF WORLD CLASS TEST EQUIPMENT FOR UNDER $300! potentiometers, audio experimenta- tion speaker... plus a lifetime guar- antee on all breadboarding sockets! You have everything you need right there in front of you! PB-503— one super test station for under $300! Order yours today!! Call toll-free for details 1-800-572-1028 GLOBAL SPECIALTIES Mntvrplex fndujfri'ej A016 Global Specialties. 7 F u 1 1 on Terrace . N ew Have n . CT 06 5 1 2 . compan y Telephone: (203) 624-3103. c Interplex Electronics. 1990. All Global Specialties breadboarding products made in USA. ProtoBoard is a registered trademark of Global Specialties. to to CIRCLE 184 ON FREE INFORMATION CARD WIM^UM*-- A review of the latest happenings in electronics. o z O cc h- o UJ I o o < Base-3 logic system A new family of digital logic, based upon the trinary ("base 3") system, has been developed by Edinboro Computer Instruments (Edinboro, PA). It is based on a new circuit, dub- bed the "Tri-Flop" — a trinary version of the commonly used flip-flop. The Tri-Flop, with three output connec- tions, can exist in any one of 27 states, compared to the Flip-Flop, with two output connections, which can exist in any of four states. The Tri- Flop allows significantly more data to be contained in the same size data registers that are presently used in binary systems. It could pave the way to fax and modem transmission speeds at least ten times faster than current rates, and allow a new wave of miniaturization in all kinds of elec- tronics. According to the device's de- veloper and Edinboro Computer president, Tom Scarpa, the Tri-Flop has been in existence for more than 20 years. However, because there never was a practical way to interface the trinary device to existing binary- based electronic equipment, the trin- ary system had no practical or com- mercial value. Recent developments in semicon- ductor theory have allowed the de- velopment of the circuitry required for such an interface. It includes a "Bi- Tri" binary-to-trinary translator that performs the conversion in hardware in nanoseconds; a "Tri-Bi"trinary-to- binary translator for getting the re- sults of a trinary operation back into the world of conventional binary com- puters and digital logic; and a "Quad State Interface," which is similar to the three-state interface presently used in binary systems but which adds a fourth (high impedance) state that provides connection circuitry that can be switched open or closed, enabling only seelcted units to be connected to a common bus path- way, thus avoiding bus contention. A 16-bit trinary memory register has been built that holds more than 43 million bits of data, which repre- sents an incresase of more than 650 times that of conventional binary regi- sters. A 32-bit trinary memory regis- ter, which holds more than 470,000 times the data contained in that of conventional binary units, has also been designed but not tested, ac- cording to Scarpa. Initially, the company plans to apply the new circuitry to the field of tele- communcations. The new system, which, according to the company, promises to increase the speed of fax and modem communications ten- fold, consists of an interface box at each end that will plug into the serial port of a conventional computer sys- tem. Edinboro Computer plans to lease the equipment to high-volume com- munications users. Future applica- tions of the trinary system are expected to be in medicine, industrial control, and military systems. By re- ducing the number of interconnec- tions required in solid-state modules for equivalent functions, the Trinary system has the potential to enhance miniaturization and improve reliability. Medically implantable miniature com- puters for control of artifical organs and prosthetic devices are another possibility being considered. IBM'S 16-MEGABIT MEMORY !C, shown on a postage stamp, can read all of its 16,777,216 bits of information in Vb of a second, which is several times faster than the blink of an eye. 16,000,000-bit memory chip IBM has fabricated a 16-million-bit computer memory chip — four times the storage capacity of today's most advanced memory chips. The chip was at their existing semiconductor production line in Essex Junction, VT to demonstrate its manufacturing feasibility. The dynamic random ac- cess memory (DRAM) chip operates at a very high speed, accessing the first bit of data from one of its storage cells in 50 nanoseconds (ns)and sub- sequent bits at a sustained data se- rial rate of just 10 ns per bit. At that speed, almost all of the chip's 16,777,216 bits could be "read" in Vfes of a second — several times faster than the blink of an eye. The chip, which measures about 1 /3 x 3 / 4 inch, is fabricated using an ad- vanced version of CMOS (comple- mentary metal-oxide-semiconductor) technology that allows for circuit pat- terns with dimensions as smalt as 0.5 micrometers wide. CMOS tech- nology produces chips that are denser and use less power than those made using other semiconduc- tor manufacturing techniques. The greater density is achieved through the use of a memory cell (the area of the chip that stores one bit of data) that is only 4 micrometers square, which is approximately one- third the size of the memory cell in IBM's four-megabit chip. The memory cell uses a three-dimensional "trench" structure that is dug into the silicon to store the chip's bits, instead of placing the cell on the surface of the silicon as is done with other chips. Using the trench allows for greater memory capacity without sig- nificantly increasing the size of the chip. The new chip's reliability is en- hanced through the use of error cor- recting and checking (ECC) code during opeation. Use of ECC pro- vides a five-fold improvement against failures compared to previous gener- ations of chips. IBM made no statement regarding planned availability, but our comput- ers could use them now! R-E ..-rrO 300.00°° 'I m THE ORIGINAL HAND. -COUNTER IMITATED BUT NEVER DUPLICATED ^ INPUT 50 OHM CAt- * 0J p\rVR HOtD ACXHG 9,,2/DC ■ iw«H«* Actual Size Made in the USA OPTOELECTRONICS brings you the latest in a long line of quality LED Handi-Counters™ - the NEW 2300. The 2300 has inherited the outstanding features of the 1200H, 1300H, 2400H & 1300HA. No other counter can match this family history. Additional new features include: ■ Finds frequencies from 1 MHz to 2.4GHz. • Display Hold Switch. • Dual MMIC Amplifiers for maximum possible sensitivity. • Continuous Range. No cumbersome range switch. • Hi-Tech Painted Finish. More rugged than anodized cases. • 600 mA Hr. Batteries. Not the cheapest but the best! ■ 17 years of quality and dependability to back our products. Function Flange Display 8030 3000 Freq, Period Freq, Period. Ratio. Interval Raiio, Interval, 2600H 260QHA 22I0A 2300 Frequency Frequency Frequency Frequency 10Hz- 26GHz 10Hz- 2 6GHj 10 Dign lOD.qir LCD LCD w/Funetiori w/Function Annunciators Annunciators 1MHz- 2 6GHz 1 Digit LCD 1MHz- 2.6GHz 10 Digit LCD FtF Signal 1 6 Segment 1 6 Segment 1 6 Segmeni Strength Adjustable Adjustable Adjustable Indicator Bargraph Bar graph Bargraph Price S579 S375. S325. S225. 10Hz- 2JGHZ SDigrt LED S199. lMHz- 2.4GHz 8 Dlgil LED Model 2300 1 MHz ■ 2.4GHz Frequency Counter $ 99. NiCad 23 Custom internal NiCad Pack (installed) $ 20. AC90 110VAC-9VDC Charger/Adapter $ 9. Complete Package Model 3300. Interna! NICads S A/C Adapter $128. SsnMFVity *i la*lOniV rypical. Time Base : 1 ppm : -5ppm add $75 ■ LEO Models. : 2pp*n ode $60 LCD Models. Nrcads & AC chnroer'adajMcr included except for 2300. "For ?9G0 NiCad mstaBed. S?0 S AC charoeri'adapltir. $9 Carry case And a (nil line* at probes and antennas are available. Oia year pans A labor Warranty on all products FACTORY DIRECT ORDER LINE 1-800-327-5912 FL(305)771-2050 • FAX{305)771-2052 5821 NE I4lh Avenue * Fort Lauderdale. FL 33334 3 Weeks. 5% Shipping Handling. (Maximum $f0) U.S. & Canada. 15% outside continental U.S.A Visa and MasterCard accepted- C Z m CIRCLE 185 ON FREE INFORMATION CARD 'il.H.liUVi: What's new in the fast-changing video industry. DAVID LACHENBRUCH CO y z O x r- o 6 < EC • HDTV uncertainty. Wide screen TV sets with HDTV monitor capability are now on the market in Europe, but there is increasing uncer- tainty about the Future of widescreen and HDTV broadcasting there. As re- ported in the U.S., manufacturer Thomson (which owns the RCA and GE brands here) now has TV sets on the market with 16:9 ratio picture tubes, designed to receive all TV standards, but specifically aimed at the satellite-transmitted European D2MAC system and the eventual transition to the high-definition HD- MAC version. However, after a fiasco in MAX broadcasting by satellite to England (Radio-Electronics, Feb- ruary 1991), powerful European forces are fighting to end Europe's commitment to MAC and HD-MAC. Those forces, some of them ob- viously aiming at keeping the en- trenched conventional PAL and SECAM broadcasting systems, point to work being done in the United States on digital HDTV systems and are urging that the European com- munity reconsider its commitment to analog HDTV, Thomson, although committed to pushing the MAC sys- tem, points out that its current wide- screen TV sets have the ability to receive PAL and pick up transmission in any HDTV system with the use of a decoder. • Hughes projection TV. Hughes Aircraft, which had been talk- ing with Korea's Samsung about part- nership on a unique new system of projection TV (Radio-Electronics December 1990), now is discussing possible arrangements with the Jap- anese. Hughes would like to hook up with a company experienced in man- ufacturing and selling consumer elec- tronics to exploit the consumer version of its lightvalve projection system, which has been widely used in military and commercial applica- tions for computer displays. Hughes now has developed the system to the point where it can accommodate vid- eo's high speed, and the company feels that the system is ideally suited to HDTV, Very little is known about the Hughes projection system as it ap- plies to TV, except that it employs three LCD's as lightvalves and uses a cathode ray tube as the picture source. A high-intensity light shines into polarizing mirrors, in effect ampli- fying the picture from the high-resolu- tion CRT, according to those who have seen the system. The projection system is Hughes' second recent venture in the field of consumer TV. The first is the Sound Retrieval Sys- tem (SRS), which has been licensed to Sony and Thomson Consumer Electronics as an audio system for TV. However, Hughes has no plans to license its lightvalve projection sys- tem to all comers. Instead, it would rather have an exclusive partner to share in the development of the con- sumer version. • A victory for 8mm. Sony, which lost the battle of VCR formats when its Beta system was eclipsed by VHS, has won the war of the cam- corder formats. While the outcome was never in serious doubt in Japan or Europe, in the U.S. the full-size VHS format held a strong lead for several years, and in the compact field JVC pushed its VHS-C varia- tion. The full-size VHS format has held a commanding lead in the U.S. over both mini formats— VHS-C and 8mm. However, in 1990, for the first time, the American public chose minis, with 51.3% buying the smaller formats, according to the Electronic Industries Association. Although the EIA doesn't break down its figures between 8mm and VHS-C, U.S. gov- ernment import data indicate that some 70% of those compact video- cassette recorders are in the 8mm format. Two more important brand names have jumped aboard the 8mm band- wagon. Following RCA, Zenith, and Hitachi, the latest brands to offer 8mm camcorders in the United States are GEand Fuji. The GE brand, fielded by Thomson, also offers VHS and VHS-C formats. Fuji is offering camcorders on the U.S. market for the first time, and its products are exclusively in the 8mm format. More converts are expected, and virtually all brands could soon offer 8mm vid- eo equipment in addition to full-size VHS. • New 8mm sound. When the 8mm format was introduced, it was equipped with two separate sound systems — stereo AFM and an 8-bit digital mono system. The digital sys- tem has since evolved into stereo. In the meantime, the VHS group has announced the development of a 16- bit stereo audio system as an option for Super VHS, Now the 8mm group, not to be outdone, has developed a 16-bit soundtrack for HiS. the high- band equivalent of Super VHS. Like the S-VHS optional audio track, the HiS version uses sampling frequen- cies of 48 and 32 kHz, the latter de- signed to record from direct broad- casts of Japan's TV satellites with digital sound. Neither system is ca- pable of direct recording from the compact disc's 44.1-kHz sampling frequency, presumably because of Japanese reluctance to antagonize recording companies, which fear copyright violation. Although it was announced more than a year ago, the S-VHS sound system wasn't avail- able in any recorders at our press time. And the eleven 8mm manufac- turers announcing the new HiS audio didn't set any specific time schedule for its availability, either So far, the battle is between high-decibel digital press releases. • One-pound projection TV. We haven't seen Fuji Photo's proj- ection TV set. but the description from Japan sounds as if it could dou- ble as a pretty good flashlight. It weighs just one pound, and its dimen- sions are about the equivalent of two VHS cassettes stacked together. It operates on a rechargeable battery and can project a picture up to 40 inches diagonally. However, it has one thing that a flashlight doesn't— ster- eo speakers. R-E SELECT 5 BOOKS 3376P SI 4. 95 Membership Benefits * Big Savings. In 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, describ- ing 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 automatically. If you prefer another selection, or no book at all, simply indicate your choice on the reply form provided. You will have at least 10 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 1 days without obligation! * Exceptional Quality. All books are qual- ity publishers' editions especially selected by our Editorial Board. 3103 S27.95 Counts as 2 3414 $33.95 Counts M 2 3734P sie.95 IHR HAHSICOK ctomcw A OHIltiiriWrMi jccmiTSlJ Wf«5 A w Tift ! 3101P $19.4S 3205 S24.A& 1991 ELECTRONICS BOOKCLUB Blue Ridfl* Summit. PA 172944810 i|H Electronics Bdqk Cljb s ji# Blue Ridge Summit. PA 17294-0810 Please accept my membership in the Electronics 6o°k Club and send the 5 volumes listed below, billing me $4,95. If no! satislied. I may return the books wilhin ten days without Obli- gation and have my membership cancelled, I agree lo purchase at least 3 books at regular Club prices during the next 12 months and may resign any time thereafter, A shippingShand- ling charge and sales ia* will be added to all orders. City Slate Signature Valid 'or new members only. Foreign applicants will receive special ordering inglrutfJonj. Canada Jnu9l rn.Tiil in U S. currency Thts order subjecl lo acceptance by The Eteclronlcs Bock Out- RPIE691 Zip Phone 3241P S1S.95 3170 132 9S |T1 All books are hardcover unless number I is iollowed by a "P" lor paperback. ASK R-E Write to Ask R-E, Radio-Electronics, 500-B Bi-County Blvd., Farmingdale, NY 11735 SAFE CHARGING 1 am using 12-volt 4-amp/hour rechargeable batteries for my camcorder and need a good charger for them. I've been using a transformer but I can never tell if I'm overcharging them. Do you have a circuit that can safely charge the batteries? — L. Shedler, Folsom, CA When you consider all the brain damage you have to deal with if you want to use Ni-Cd's, it's amazing that anyone still uses them. That probably says more about the state of re- chargeable-battery technology than anything else. Despite internal short- ing and recharging hassles, they're more popular now than they ever were. The key to success with Ni-Cd's is knowing how to recharge them with- out damaging the cells and there have been zillions of words published in this magazine and others (our words, of course, are much better) about how to take care of Ni-Cd batteries. A quick trip to your library will result in your finding out more than you ever wanted to know about the use and abuse of Ni-Cd's. The rate of charge that can be used on a particular Ni-Cd cell depends on how it's constructed and its capacity. Most cells can't be rapidly charged without circuitry that monitors either their internal temperature or pres- sure, or both. That's because a Ni-Cd generates oxygen as it charges and, if the rate of charge is too high, the gas will be produced faster than it can be absorbed in the cell. As you can guess, the result of the overcharging is usually a rupture of the cell seals — and if that happens, the battery is history. The safest charge rate for any cell is the so-called C10 rate. That refers to the time it would take a battery with a voltage of one volt per cell to reach full charge in ten hours. In more practical terms, the number is one tenth the rated amp hours of the bat- tery. In the case of the cells you're using, that translates to a charging rate of 400 mA. You can use any circuit you want to charge the battery as long as you calculate the correct resistor value to keep the charging current at 400 mA. Even the voltage you apply to charge the batteries isn't as important as keeping the charging current from ex- ceeding the CIO limit. FIG. 1— WHEN CHARGING Ni-CD's. this circuit will monitor the battery voltage and provide you with a signal when a certain, presettable voltage has been reached. The circuit shown in Fig. 1 will monitor the battery voltage and pro- vide you with a signal when a certain, presettable voltage has been reached. The signal can be used to sound an alarm, trigger a relay, or whatever else you might need. The relay could drop the charging rate by adding another resistor in series with the current limiter or even disconnect the charger completely. When you first apply the charger to a drained battery, the voltage in the system will drop to the battery volt- age and, as the battery continues to charge, the system voltage will rise. When it reaches a level determined by the setting of R3, 01 will turn on and you'll get current flow through its collector-emitter junction. As shown it will turn on an LED but, as I men- tioned, you can replace that with a relay or whatever you want. There's absolutely nothing critical about building the circuit and its ac- curacy is totally dependent on how well you can tune R3, That's why it's listed as a multiturn potentiometer. All you have to do to calibrate it is to apply 12 volts and slowly adjust R3 until the LED (or, of course, the relay) turns on. LACK OF TACH I have a digital tachometer that I used successfully for years on an older car where it was connected to the ignition system's dis- tributor points. I now own a 1985 Chevy with an electronic ignition system that I know nothing about. How can I pick up a suitable sig- nal to use the tach. and do I have to modify the digital input? — T. Ulijasz, Brookfield, Wl A friend of mine had a similar prob- lem a few years ago when he traded in his old car and got a new one. I had built a digital tach for him and he'd been using it on his old car for years. When we went to put it on his new car I opened the hood and discovered that he'd bought a diesel. And you think you have a problem! I can't speak with authority on every car there is — I'll take them as they come. Since your car, unlike my friend's, has a "real" ignition system, there's always someplace to pick up an input for the tach. Although you haven't mentioned it in your letter, I'm assuming that the electronic ignition in your Chevy is factory- in stalled. If that's the case, there are loads of books (like the Chilton manuals) that tell you every- thing you could want to know about the inner workings of your car. You might even be able to get information about the system from GM. What you really need is the schematic for the car's electrical system. If it turns out to be absolutely im- possible for you to find out how things are wired up in your car, you can always take the signal from the most obvious place of ail: right off the spark plugs. Since you didn't tell me exactly how the tach was working in your old car, I'll have to do a bit of" guessing. The input conditioning you have should be good no matter where you pick up the signal in your car. You may have to change the value of the cur- rent-limiting resistor depending on the voltages you find in the car but that's about it. 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It can be done inductively by wrapping a few turns of wire around the ignition cable or by run- ning a lead into the cap of the spark plug. Try an inductive pickup first be- cause it's the safest way to go. You may have to experiment with the number of turns but. since such a huge spike is generated when the plug fires, you shouldn't have any trouble getting a pulse that can be fed to your tachometer. If, for some reason, inductive coup- ling is impossible, you can get the pulse from the cap of the plug but you have to be careful when you do this. Don't, under any circumstances, cut into the ignition wire leading to the plug. The cables are designed to properly isolate the high voltages and messing with the insulation can *Save on cable rental fees !» CABLE TV DESCRAMBLERS WE'LL BEAT ANY PRICE I CALL TOLL- FREE 1-800 284-8432 JERROLD-TOCONI-ZENITH HAMLIN-0AK-PI0NEER SCIENTIFIC ATLANTIC • 2.4 HOUR SHIPMENTS ! 'MONEY BACK GUARANTEE ! 'FREE CATALOG & INFO I 'QUANTITY DISCOUNTS I MASTER CARD / AMEX / VISA / C.O.D. Have make and model number of equipment used in your area ready 1-800-284-8432 CABLE WAREHOUSE 4700 N, HIATUS ROAD .SUN RISE.F1A33351 L | _ WO FLORIDA SALES J CIRCLE 190 ON FREE INFORMATION CARD cause problems from moisture or arc- ing and lead to misfiring or a substan- tial decrease in engine efficiency. And be sure to use cable that can safely handle the high voltage at the plugs. If you have problems with arcing, get yourself a good supply of RTV putty to insulate the cable. You may also have to make some changes to the logic in your tach be- cause the number of sparks per sec- ond at the plug may be different than the number you were getting from the distributor. Remember that you're getting one spark for each two revolu- tions of the engine. MULTILAYER WOES The keyboard connector on my AT motherboard broke so I un- soldered it from the board and re- placed it with a new one. The problem I have now is that the board is a multilayer one and I think one of the traces in a middle layer has broken. Do you know of any way to repair a trace on an inner layer of a multilayer board?— V. Deeoh, New York, NY You've got a big problem. I've been faced with shorts on inner layers and the only way I've been able to repair the board was to lift all the legs that sat on the trace and connect them to a totem -pole wire that I ran above the board. If, as you suggested, you've broken a trace on one of the middle layers of the board, the only way I know to repair it is to make the con- nections with new wire on top of the board. I've never found a way to do anything to the copper buried inside the board. That technique may not sound too difficult but it presupposes that you know which trace is broken, and which pins on which components are supposed to be connected to- gether — You need the schematic. If you don't have the schematic, I don't know if a repair is even possi- ble. The internal copper is buried in the board and you can't usually hold to board up to the light and follow the traces, I'm sorry to tell you that I think your chances of making a repair to a buried trace on an undocumented mother board are only slightly better than your chances of getting a quick an- swer from a government official. It's theoretically possible but 1 wouldn't count on it. R-E 48 HOUR SHIPPING ELENCO & HITACHI PRODUCTS AT DISCOUNT PRICES 48 HOUR SHIPPING Hitachi RSO Series (Portable Real-time Digital Storage Oscilloscopes) VC-6023 - 20MHz, 20MS/S $99/mo* $120/mo' .$13o7mo* S125rmo - $200Mo" VC-6024 - 50MHz, 20MS/S _ VC-6025 - SOMHz, 20MS/S _ VC-604S • 100MHz, iOMS.'s LEASING AVAILABLE For all Hitachi Scopes - Call for details ' Based on 24 months except V-1150. VC-6045. VC- 61.15 (36 months) VC-G145 - 100MHz, 100MS/S RSO'S trom Hitachi leature roll moda, averaging, save memory, smoothing, interpolation, pratriggering, cursor measurements. These scopes enable more accurate, simplier observation ot complex waveforms, in addition to such functions as hardcopy via a plotter interface and waveform transfer via the RS-232C interface. Enjoy the comfort of analog and the power fo digital. 20MHz Elenco Oscilloscope $375 MO-1251 • Dual Trace Component Tester . 6" CRT • X-Y Operation - TV Sync ■ 2 P-l Prabes Hitachi Portable Scopes DC to 50MHz, 2-Channel, DC Offset func- tion, Alternate magnifier function V-525 - CRT Readout. Cursor Maas. S1 ,025 V-523 - Delayed Sweep $995 V-522 - Basic Model JB95 V-422 - 40MHz $795 V-223 - 20Mhz delayed sweep $695 V-212 - 20MHz $425 HITACHI COMPACT SERIES SCOPES This series provides many new functions such as CRT Readout, Cursor measure ma nts fV-1 085/1 055/665), Fre- quency Ctr (V-1085). 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Features shon circuit protection, all supplies AM/FM Transistor Radio Kit with Training Course Model Att'FM 108 $26.95 14 Transistors ♦ 5 Diodes Makes a great school project True RMS 4 1/2 Digit Multimeter M-7QO0 $135 .05% DC Accuracy .1% Resislance with Fraq. Counter and Deluxe Case GF-80T6 Function Generator with Freq. Counter $249 Sine, Square, Triangle Pulse, Ramp. .2 lo 2MH2 Freq Counter .1 - 10MHi GF-SQ1 5 without Freq. Meter $179 Function Generator Blox #9600 $28.95 *tl* Provides sine, triangle, square wave Ircm 1Hzto 1MHz AM or FM capability Learn to Build and Program Computers with this Kit Includes: All Peris, Assembly and Lesson Manual Model HM-8000 $129.00 Wide Band Signal Generators Starling from scratch you build a complete system. Our Fvf on-Master trainer teaches you to write into RAMs n ROMs and run a 8085 microprocessor, which uses similar machine language as IBM PC. Robotics Kit for above (MM80TO) 71.95 WE WILL NOT BE UNDERSOLD! UPS Shipping: 48 States 5% (S3 Min 510 Matt) Shipping IL Res.. 7% Tax FAX: 708-520-0085 SG-9O00 S129 RF Fraq 10QK-450MHZ AM Modula- tion ol IKHz Variable RF output SG-9S0Q w/ Digital Display & 1 SOMHz built-in Counter $249 MOVIT EDUCATIONAL ELECTRONIC ROBOT KITS The MOVIT line is a series ot com- puterized (and logic controlled) battery robot kits that can teach the basic prin- ciples of robotic sensing and locomo- tion. Each ol the kits lealures pre-as- sembled PC boards, hardware and mechanical-drive systems that can be handled by almost anyone from ages 1 and up. Only basic hand tools are required for assembly. These lancinat- ing robots allow you lo experience and team any one of the following lealures: sou nd se nsor, remote control , i nfra-red sensor, wired control and / or program- mable memory. The MOVIT line has provided the lulure with an innovative electronic educational kit. They are af- fordable robots that can entertain as wall as educate. Now meelthe family I MV-912 Avoider Inlra-red S4E.95 MV-915 Piper mouse Sound Sansor $45.95 MV-916 Pappy Sou rrd Touch $25.95 MV-931 Mr. Bootsman Wire Control $35.95 MV-932 Calral Remote Control $45.95 MV-936 S-Cargo Sound Sensor $45.95 MV-939 Medusa Sound Sensor $29.95 MV-963 Line Tracker Infra-red S45.9S MV-966 MajitaSound/Toucri $29.95 Y-01 Bobotic Arm Robotic Control $45.95 BT-802 Grand Piano Electronic Piano $29.95 BT-B05 Roulette Digital Wheel $35.95 C & S SALES INC. 1245 Rosewood. Deerfietd. II. dill) 1 5 iXOOi 2'>2-77ll [7081 541-1)71(1 H f hqi i**-c a*ii 15 Day Money Back Guarantee 2 Year Warranty p "«* &ubl«t to awngu WRITE FOR FREE CATALOG CIRCLE 109 ON FREE INFORMATION CARD to 13 LETTERS Write to Letters, Radio-Electronics, 500-B Bi-County Blvd., Farmingdale, NY 11735 PARTS DILEMMA I hope that my letter is just one of many that you receive saying that Radio-Electronics has let its read- ers down by featuring a construction project for which no parts kits are available. I refer to the "Sweep-Mark- er Generator" article, by John Wan- namaker, that appeared in the February and March 1991 issues. Ac- cumulating the necessary parts — some of which area bit exotic — might not be difficult for engineers, but it is no easy task for hobbyists. While such articles are of academic inter- est, without a parts kit the ultimate interest is little more than academic. SIMON L SCHEINER Cherry Hill, NJ Your frustration about not having a parts kit available is understandable. My frustration at not being able to afford to make such a kit available is even greater. As you might have noticed, I do supply the one item that cannot be purchased elsewhere: the printed-circuit board. Along with the boards, I provide a list of parts sup- pliers with addresses and telephone numbers. Unfortunately I neglected to mention in the article that I also offer (at my cost, $2.00) an informa- tion sheet that contains additional in- formation that did not appear in the article that readers might want as they build the generator. I order components just as any hobbyist would, and occasionally pay a penalty for not meeting minimum- order requirements. There are a great many people who order the PC boards and do everything necessary for the satisfaction they get from building from scratch. In the case of the sweep generator, the satisfaction seems to be not so much in the con- struction as in having such a unique device at their disposal — so that the g gathering of components and the ac- 2 tual construction seem to be worth § the inconvenience. q Should the article not have been 3 published? Let me indicate the enthu- ^ siasm I've heard thus far from some 5 of the orders for boards: c "...this new generator looks fabu- lous and I can 't wait to get started. " "I've been looking for a long time for such a generator..." "Your project is perfect for my needs. " "...anxiously awaiting the next is- sue of Radio-Electronics so that I can get the artwork to make the boards. Thanks. " In addition to the above, as a school teacher I believe that academ- ic interest alone makes the publica- tion of many such articles worthwhile. JOHN WANNAMAKER STANDING UP FOR MACINTOSH I was slightly amused by Jeff Holtzman's rebuttal to Raymond Cheng's letter in the April 1991 issue of Radio-Electronics, but when he brought up Apple Computer's Macintosh. I had to write this letter. He mentioned that "Windows has done more for promoting advanced computing environments than every- thing done by all the Amigas (and all the Macintoshes)...". Give me a break! Windows on MS-DOS ma- chines are nothing more than feeble attempts to turn them into a Macin- tosh. However, you encounter fewer problems on a Mac than you do with any version of Windows. The Mac is far more consistent, easier to use, and overall better to use than a cheap IBM clone using Windows. Mr. Holtzman also stated that "Ap- ple continues its steady decline in the marketplace," Wrong again. There may be more dime-a-dozen MS-DOS clones than there are Macs, but the facts are: Macs are out there. In fact, Apple has lowered its prices on them, introduced new ones, and just about sold more Mac Classics than they can make. Apple computers still dominate the educational market, ever since the introduction of the Ap- ple He. The new Macintosh LC will bridge the gap between Apple lie computer labs and Mac labs. People should consider it a blessing that there are other computers available, without having to resort to the MS- DOS world. Radio-Electronics should be more courteous to people who use computers other than your favorite. As long as there is a choice in se- lecting a computer other than an MS- DOS clone, there will definitely be "advanced computing environments" in the near future. WESLEY FITZPATRICK Tuscaloosa, AL APRIL FOOLS I just received by April 1991 issue of Radio-Electronics and couldn't believe the article "Poor Man's Laser Printer." Has anyone really tried to do this? I have to be honest — I read the article fully expecting it to be a gag. The author, Paul Renton, made it sound so simple. I've been in the cop- ier business for over ten years and I can tell you flat out. it's not that easy. First off, the copier is designed with a focal length based on the "original" being flat on the glass. A monitor is curved, and because of the case, it will be an inch or more off the glass. Second, the author says you need to remove the exposure lamp. That's right, you would — except for the fact that any copier I've worked on will give you an error message when the lamp circuit is open. The copier won't ever run with the lamp out. Third. what do you do with a copier that has a moving top? The drive system won't handle the weight of a monitor sliding back and forth. Fourth, why does the author nof have a laser printer? He has an $8000 copier in the photo. I'd like to think he could afford a $900 laser printer. You folks have some fine articles in your magazine but. come on guys, get real! (By the way, the "C" clamps were a nice touch.) JEFFREY J. WILLARD New CumbeHand, PA AN ELEGANT SOLUTION I enjoyed your article. "Poor Man's Laser Printer" (April 1991). but I think that the "C" clamps and Bungee cords are an inelegant solution some- what below Radio-Electronics usual above-average standards. Here is my suggestion: 14 Cable TV Descrambler Article Parts We stock the exact Parts for several articles published in Radio-Electronics magazine on building your own Cable TV Descrambler. February 1984 SB-3 Type 701 Parts Pkg $19.00 Includes all original parts. 702 PC Board. ...... .7.95 Original 3X4 etched, drilled and Si Ik- Screen pc board. 704 AC Adaptor 7.95 12 to 18 Volt DC @ 200ma. 701, 702 & 704 29.00 All three for special saving. February 1987 Tri-Mode 301 Parts Pkg. 29.00 Includes all original parts. 302 PC Board 7.95 Original 5X8 etched, drilled and Silk-Screen pc board. 304 AC Adaptor 7.95 12 to 18 Volt DC @ 200ma. 301, 302 & 304 39.00 All three for special savings. Tri-Mode Tutorial. .7. 95 26 pages of in-depth info. May 1990 Universal 901 Parts Pkg $49.00 Includes all 902 PC Board 9.95 Improved 4X7 etched, drilled and Silk-Screened pc board. 904 AC Adaptor 8.95 12 to 18 Volts AC @ 350ma. 901, 902 & 904 59.00 All three for special savings. Snooper Stopper.. .$39. 00 Prevent Descrambler detection with snooper stopper/data blocker and protect your privacy. Includes free article on Cable Snooping. Macrovision Kit.. .$29. 00 Macrovision now you see it, now you don't with our macro-scrubber kit. Originally Published in Radio-Electronics . Signal Eliminator (tunable notch filters)... .$29.95 Model number & channel; #713 (channel 7 to 13) #23 (channel 2 & 3) #1417 (channel 14 to 17) #46FM (channel 4 to 6 & FM) #1822 (channel 18 to 22) 1 remote replaces 3... The MAC 20 wireless remotes replaces any three combinations; TV, VCR, Cable Converter, Stereo, CD or other entertainment system. MAC 20 $59.95 A VCR in every room.. with the first FCC approved wireless home broadcast system. 120 ft. range. VC2000 ....$99.95 70 Channel Cable TV Converter $89.95 * 6 Function Infra-Red remote. * Compatible with alt External Descramblers. * Fine Tuning. * Channel 3 or 4 switchable output. * Memory & Recall. * STD, HRC & IRC compatible. CALL TOLL FREE 1-800-332-3557 Outside USA Call 1-508-699-6935 Visa, MasterCard and COD. Add $4.00 S&H, $6.50 Outside USA. D & D Electronics, Inc. PO Box 3310, N. 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Satisfaction guaranteed or money refunded, > rvAAy V Banner Technical Books, Inc. 1203 Grant Ave. Rockford, IL 61103 Build a sturdy, reinforced wooden mold around the entire project, ex- cluding access areas for the copier's paper tray, output bin. and controls. After covering any openings on the monitor and copier cases with mask- ing tape, carefully align the monitor on the copier glass, and fill the mold with ready-mix concrete Cone or two cubic yards should be enough). Be- fore the concrete sets, embed part of a length of heavy chain in it. Allow the concrete to cure for a couple of days. I believe you will find that this im- provement will hold the monitor and copier very securely together. It has other advantages, too. The printer's serviceability will be improved, by re- ducing the number of "Field Re- placeable Units" CFRU's) to just one. After retirement from original service, the FRU's can be reused as off-shore moorings for yachts. In this time of concern about overloaded landfills, it is good design practice to provide for reuse of FRU's. ROBERT BARNHILL Boca Raton, FL CAN'T BE FOOLED AGAIN! You're right, I was able to save a bundle with the "Poor Man's Laser Printer" (April 1991 J. Since I have a copier that has a plater that moves, I found it difficult to keep the monitor in place. The C-clamps were too expen- sive, so I opted for a 2-by-3 and some threaded rod to bolt the monitor to the plater. (I got those for nothing; I'm in the home-remodeling business.) The lamp on the copier was already burned out, I think. Well, let's put it this way: When I opened the case and pulled out some wires, the lamp stopped working. Who said you need an electronics degree! Copies came out great, after a little adjustment on the monitor's con- trast. The only thing I haven't figured out is how to use the monitor while it's still bolted down. PS. I wrote to you on my type- writer — you know, the old Smith Cor- ona Portable. The plans you printed in last year's April issue on how to add a monitor to that typewriter were won- derful. The typewriter and the car bat- tery make this better than any portable on the market today. It's true QWERTY, too, and has non-volatile memory (me!). I can't wait for next year's April issue! LANCE HAVILLARD Gaithersburg, MD PC REALITIES I am a 70-year-old retired missile engineer with not enough time in the day for my hobbies and life's neces- sities. Two of my hobbies, amateur radio (K6SAR) and computer hack- ing, drew me to Radio-Elec- tronics. Your magazine's composi- tion just about fulfills my needs. The elementary electronics articles are good fundamental reviews that re- fresh — and in some cases, instruct — my dwindling memory regarding basics. Information on projects and advanced equipment is food for thought and personal planning. I chuckled and nodded my head as I scanned Raymond Cheng's letter "Amiga Amigo" in the April issue. I, too, feel that my favorite computer is being short-changed by the media. In my situation, my computer chro- nology took the following steps: a Commodore 64; an Atari 1040ST (30MB hard disk, etc.); and an IBM clone (386SX) package including CD ROM, sold by DAK Corp. I use the computers according to their spe- cialties — the Commodore for packet radio, the Atari for graphics and DTP, and the IBM clone for the rest of my needs. I love them all, and wouldn't part with any of them. I decided to buy the IBM clone because I could see the handwriting on the wall. Popular inter- est in, and factory support for, the other two machines that I have are dropping off. Programmers are leav- ing those computers in droves. Even technical magazines that once sup- ported them are disappearing from the newsstands. One other indication of that trend is that the local Commodore and Atari clubs no longer exist, whereas the IBM-user club is bursting at the seam with members. Of course, another problem is the lack of standardized operating systems for those ma- chines, I agree with Mr. Cheng that the Atari is far superior to the IBM clone but, unfortunately, it is a dying breed. Once again, the consumer has been led down the primrose path, only to be left — expensively — high and dry. While, in essence, I agree with Jeff Holtzman's reply, I take him to task for using sarcasm and getting into mud- slinging. That should be a no-no for Radio- Electronics editors. ED GLEMBOTSKl San Luis Obispo, CA R-E 16 CIRCLE 67 ON FREE INFORMATION CARD Electronics DTftDLrDD 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 V4 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 607, Bedford Hills, NY 10507. (914) 232-3878. CIRCLE 127 ON FREE INFORMATION CARD gfSSS^l-^^VSSStk COMPUTER KITS, BOARDS & COMPO- NENT PARTS. Designed to the highest de- gree of quality and reliability available today. They're fun, easy to build, educational, IBM compatible, very powerful, and at great prices All items are pre-tested. include a full year warranty, step by step assembly manual, and free tech support. Assembly available at no extra charge. For free catalog contact: GENERAL TECHNICS, P.O. BOX 2676, LAKE RONKONKOMA, NY 11779, or call (S16) 981-9473. VISA, MasterCharge, Ameri- can Express, COD. CIRCLE 189 ON FREE INFORMATION CARD contact east ES/UfElMK I SfflfflSG FREE CATALOG OF TEST INSTRUMENTS & TOOLS is packed with thousands of prod- ucts for testing, repairing, and assembling electronic equipment. Featured are brand name instruments such as Fluke, Tektronix, Leader, Weller, 3M plus many more. Also in- cluded are DMM's. hand tools, power sup- plies, tool kits, test equipment, static supplies plus many other new products. Orders placed by 4 PM are shipped before we go home! CONTACT EAST, 335 Willow St., No. An- dover. MA 01845, (508) 682-2000, Fax: (508) 668-7829. CIRCLE 5S 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 XST500 SUPER-MINIATURE FM transmitter uses Surface Mount Technology (SMT)! Own the smallest high performance FM transmitter available. Transmits whispers to any FM receiver up to a mile away. Uses 9V battery. Complete, easy to assemble kit, with SMT components already assembled to cir- cuit board. $39.95 Cash, VISA, MC. COD add $5. XANDI ELECTRONICS, 201 E. South- ern Ave., Suite 114, Tempe, AZ 85282. 1-602-829-8152, (1-800-336-7389 orders only). CIRCLE 180 ON FREE INFORMATION CARD CABLE TV CONVERTERS AND DE- SCRAMBLERS SB-3 $79.00 TRI-B! S95.00 MLD-$79.00 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 GET YOUR RECHARGE CATALOG FREE... EARN BIG SS IN YOUR SPARE TIME— All supplies and Do-It- Yourself kits with complete instructions available. Sup- plies cost from $9.95 in qty and you can sell recharged toner cartridges for $40.00 to $55.00 each. Printers include HP LaserJet and Series II, Apple LaserWriter, QMS, etc. Canon PC-25 Copier also. CHENESKO PRODUCTS, 62 N Coleman Rd., Cen- tereach. NY 11720, 516-736-7977, 800-221-3516, Fax:516-732-4650 CIRCLE 182 ON FREE INFORMATION CARD SIMPLYSNAPTHEWAT-50MINIATUREFM 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 C m J 17 The two most comprehensive electronics Take any 3 books for only $ 9 as your introduction to the new ELECTRONICS ENGINEERS' BOOK CLUB 95 CO o z O £E H O Hi < EC BLBCTROMC iCORCurrs WITH APPLICATIONS I 2920 $29.95 A wealth of electronic circuits and information on building working devices. 336 pp. PRINTED CIRCUITS DE5lA.B JACKSON. MiSSISSIPPI 39212 CIRCLE 5S ON FREE INFORMATION CARD CABLE - TV SIC NAL REA4CVERS •FOR ELIMINATION OF SEVERE INTERFERENCE ■FOR "CENSORING- OF ADULT BROADCASTS * ■ ATTENUATION ■ 4S dS TYPICAL ■ BANDWIDTH - * MHz AT 5 dB POINTS ■ INSERTION LOSS - 2 dB MODEL TuNIHG RUMC CHANNELS PAS 9 EA HO PfiiCC SHIPPING !3H 50-SE MHz 2.3 for S m*14r ham) 50-300 MHz 130 SHIPPING Of C.O.D. CHARGES 48 FM '.: ■:■: '.'■■. 4 56 formiFMl $0-300 MHz S30 1417 12CM44 MHz 14(A) 1519] 15 [CI 17(0) $0-400 MHz !?? 1B22 144-174 MHz iE:Ei"3 : :;: r, ■-. ■ ;r 50-400 MHz 130 713 174-J16MHZ 719.1011 12.13 SO .400 MHz S30 3 for $75 - 1 for $200 - mix or match CALL TOLL FREE FOR COD OR5ENDCHECKTOORDER FAST DELIVERY 30 DAYMONEY SACK GUAR ANTE E (3 FILTER LIMIT} Star Circuits P. O. Box 94917 Las Vegas, NV 89193-4917 1-800-433-6319 c z m to to 27 NEW LIT to y z e g UJ O Q < GORDON McCOMB'S GADGETEER'S GOLD- MINE! 55 SPACE AGE PROJECTS; by Gordon McComb. Published by TAB Books Inc., Blue Ridge Summit, PA 17294-0850; Phone: 1-800-233-1128; $18.95. Although some of the projects in this book are CIRCLE 13 ON FREE INFORMATION CARD decades old and others are brand new, they all share a common thread: They are intended to spark the build- er's spirit of invention. The classic designs serve to give the reader a solid foothold in the techniques of "gadgeteering," while some of the unique new ideas serve as a jumping point from which readers can create their own de- signs. The projects range in complexity from a simple Jacob's Ladder to a com- plete laser light show, and include a plasma sphere generator, a Tesla coil, a Kirlian camera, a supercon- ductor disc, a radiation de- tector, a fiber-optic com- munication disc, a laser alarm system, a computer control interface, a holo- graphy darkroom, and a seismograph. The book is divided into 26 chapters, each of which presents one or more hands-on projects that readers can duplicate in their home workshops. Several chapters also in- clude information vital to the understanding of one or more of the projects. The book explores the sci- ence of lasers, how fiber optics work, the nature and dangers of high-voltage de- vices, what radioactivity is and how it is measured, the history of holography, light- wave communications, and piezoelectricity. The proj- ects are fully illustrated, and a list of parts sources appears in the appendix. ELECTRONIC TEST AC- CESSORIES; from ITT Pomona Electronics, 1500 East Ninth Street, P.O. Box 2767, Pomona, CA 91769; Phone: 714-623-3463; Fax: 714-629-3317; free. Highlighted in this 140- page catalog are a new 32- Etearonic Test Accessories Pomona A Hauiy ["^TimeLf lnm^Mrtii CIRCLE 14 ON FREE INFORMATION CARD pin PLCC C0.05 pin spac- ing) clip for popular EEPROM devices, and 100- and 132-pin SMT test clips for Motorola 68020/68030 and Intel 80386SX micro- processors. Additional ac- cessories included in the brochure are intended to make testing SMT devices easier and more reliable. The catalog also features new IC clip kits, coaxial/ BNC universal adapter kits, digital-multimeter test-lead kits, cable and patch accessories, and jumper kits. Ten major product categories, which are presented in an easy- to-use index, include a se- lection of jumpers and ca- bles, boxes, plugs and jacks, connectors, adapt- ors, single-point test clips, and static-control devices. OPTOELECTRONIC DE- VICES (Catalog 86-1, Is- sue IV); from Lumex Opto/Components Inc., 292 East Helen Road, Palatine, !L 60067; Phone:708-359-2790; Fax: 708-359-8904; free. This 52-page catalog contains detailed descrip- tions, dimensions, and specifications for hundreds of state-of-the-art op- toelectronic components. Included are emitters, de- tectors, laser detectors, photo-transistors, photo- diodes, optoisolators, pho- CIRCLE 15 ON FREE INFORMATION CARD to-reflectors, emitter-de- tector assemblies, chop- pers, photo interrupters, custom assemblies with IC controllers, chips, and re- mote-control receiver mod- ules. Those items have practical applications in a wide variety of consumer, industrial, and business products and systems, in- cluding audio and visual equipment, computer driv- es, copy machines, word processors, phones, fax machines, controllers, spectrum analyzers, medi- cal equipment, alarms, and meters. The catalog also contains a chart that cross references part numbers for 15 manufacturers such as Sharp, Honeywell, NEC, and Siemens; a two-page applications chart; and sections on charac- teristics, circuitry, package outlines, and specific se- lection guides, THE CAPACITOR HAND- BOOK; by Cletus J. Kai- ser. Published by CJ Publishing, 2851 West 127th Street, Olathe, KS 66061. Although capacitors are in common use, they are frequently misused due to misunderstanding their characteristics. This book aims to clear up the con- fusion by providing prac- tical guidance in under- standing the construction and application of capaci- tors. It combines theory with circuit application ad- vice to help readers under- stand what goes on in each component and in the final design. An opening chap- ter covering the fundamen- tals of capacitors as a general category is fol- lowed by chapters on spe- 2B THE CAPACITOR HANDBOOK CIRCLE 16 ON FREE INFORMATION CARD cific types of capacitors, including ceramic, plastic- film, aluminum-electrolytic, tantalum, glass, and mica. SELECTION AND USE OF PANDUIT ADHESIVE MOUNTS (Technical/ Ap- plication Data Sheet TADS-WA-14B); from Panduit Corporation, At- tention: Product Man- ager, Wiring Accesso- ries, 17301 Ridgeiand Avenue, Tiniey Park, IL 60477-0981; Phone: 1-800-777-3300, ext. 7346; free. Designed to explain how to choose and use adhe- sive mounts for wire and cable, this eight-page bul- letin provides information on types of adhesive that EJBwmurf CIRCLE 17 ON FREE INFORMATION CARD are available, guidelines for surface preparation, and short listings of applica- tions and markets. A table includes dimensions, tem- perature ranges, adhesive type, maximum loads, and cable ties. V \ltX VI It CLEANING/MAINTENANCE/REPAIR EARN UP TO 51000 A WEEK,WORKING PART TIME FROM YOUR OWN HOME! THE M0HEY MAKING OPPORTUNITY OF THE 1990S IF you are able to work with common small hand to ols , an d are fami I ia r with bas i c electronics ( i .e . able to use voltmeter, understand DC electronics). . . . IFyou possess average mechanical ability, and have a VCR on which to practice and leam. . . .then we can teach YOU VCR maintenance and repair! FACT; u p to 90% of A LL VCR nta if u n ctio n s are due to simple MECHANICAL or ELECTRO-MECHANICAL breakdowns I FACT; over 77 million VCRs in use today nationwide! Average VCR needs service or repair every 12 to 18 months! viejo's 40fl PAGE TRAINING MANUAL (ever 500 pho- tos and illustrations) and AWARD-WINNING VIDEO TRAINING TAPE reveals the SECRETS of VCR mainte- nance and repair— "real world" information that is NOT available elsewhere! Also includes all the info you'll need regarding the BUSINESS-SIDE of running a successful service op- eration! pHEE | HFrjRMflTmN CALL TOLL-FREE 1-800-537-0589 Or write to: Viejo Publications Inc. 5329 Fountain Ave. Los Angeles. CA 90029 Dept. RE CIRCLE 193 ON FREE INFORMATION CARD Try the g—jnatlin MziEctrDnics bulletin board system (RE-BBS) 516-293-2283 The more you use it the more useful it becomes. We 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 to increase your access. Communicate with other R-E readers. Leave your comments on R-E with the SYSOP. RE-BBS 516-293-2283 Pomona's Universal Adapter Kit lets you make your own connections on the spot. You get two each of industry's most popular styles; BNC, TNC, SMA, plus ^ "N" males and |B females. Plus, a special Double^ Banana Plug and Double Binding Post. And, four intermediate couplers to make i your way. A Case For Reliable Connections. There's quality in every piece, with gold plated center pins and silver plated bodies. And everything's in a hinged, plastic case for years of dependable use. You'll find the best selection of coaxial adapters in the pages of the new Pomona Catalog. See your near- est Authorized Pomona Distributor. POMONA ELECTRONICS, 1500 E. Ninth St, P.O. Box 2767, Pomona, CA 91769 (714)623-3463 FAX (714) 629-3317 . .^ FREE 1991 POMONA CATALOG! 140-pages of/teusst products and thousands qftestsohttions, ITT Pomona AN ITT EMC WORLDWIDE COMPANY Discover our strengths. CIRCLE 101 ON FREE INFORMATION CARD 29 PARTS SPECIAL-ORDER HOTLINE. Your local Radio Shack offers a huge selection of electronic components. Plus, we can special-order over 10,000 Hems from our warehouse— ICs, tubes, semiconductors, crystals, phono car- tridges and styli, even SAMS* manuals. Delivery time for most items is one week. And Ihere are no postage charges or minimum order requirements. (1) High-Speed 12VDC Motor. Up to 15,200 HPM. About 2" long (with shaft), #273-255 2.99 (2) Hobby Motor. For robotics and projects. Vh to 3VDC. About 1"*" long. #273-223 99* Heavy -Duty Plug- In DPDT Re- lays. Contacts rated 10 amps at 12SVAC. Sizer1=/Bx1x^4'; 12VDC Coil. #275-218 5.99 125VAC Coll. #275-217 5.99 Relay Socket. #275-220 ... 1.79 BATTERY SPECIAL-ORDER HOTLINE. In addition to our large in- store stock, Radio Shack can now supply almost any currently manufactured consumer- type battery— quality replacements (or cordless telephones, computer mem- ory, camcorders, transceivers, pagers and more. Discover the Radio Shack "hotline" advantage— fast service with no postage or handling charges. (1) Mini Piezo Speaker. Only is'fea" diameter. #273-091 . . 2.49 (2) "Ding-Dong" Chime. Re- quires 6 to 18VDC. #273-071 . , B.99 (3) Mini Buzzer. Loud, yet only 7 mA at 12VDC. #273-074 . . . 2.99 DPDT Knife Switch. Just the thing for low-power switching in science projects, model railroads and more. Rated 0.5 amp at 200VDC. Screw terminals. Mounting holes on base. #275-1537 1.29 Lamp Holders. For indicators and projects. Figs. 1 and 2 accept E-10 threaded-base bulbs, available at Radio Shack. (1) Round Style. Screw terminals. #272-357 . . . 790 (2) Compact. Solder lugs. #272-356 . . 996 (3) Bayonet Base. #272-355.. 67990 XLH Connectors (1) Three-Pin Plug. #274-010 ... 2.99 (2) Inline Socket. #274-011 .-. .. 2.99 (3) Panel Socket. #274-013 . . . . 3.69 (4) Adapter Trans- former. Connects XLR-lype mike lo equipment with V*" phone jack input. #274-018 . 11.99 (5) Adapter Trans- former. Connects mike with th" plug to XLR jack input. #274-017 ...11.99 (4) (5) CO o z o rr F- o UJ _1 "r 1 Since 1921 Radio Shack has been the place to obtain up-to-date O electronic parts as well as quality tools, test equipment and accessories Q at low prices. Over 7000 locations to serve you— NOBODY COMPARES £r Prices apply al participating Radio Shask stores and dealers. Radio Shack is a division of Tandy Corporation LCD DVM With Capacitance and Transistor Gain Ranges, Extra-feature digital multitester with easy-to- read 0.5" display and 10 megohm input. 30 ranges — measures AC IDC voltage and cur- rent, resistance, capacitance and transistor gain. #22-194 . . 79.95 (1) Precision Ther- mistor. Resistance changes in propor- tion to temperature. Has measurement range from -50 to + 110" C. #271-110 ... 1.99 (2) Surface- Mount Resistors. Big 200- plece assortment! Popular values, rated '/a watt, 51* . #271-313, Set 4.99 J 3) Ohm's Law iulde, Fasl an- swers to Ohm's law and parallel resist- ance problems. #271-1211 .... 59c (1) Telescoping Antenna. Ex- tends to 24': (16 styles in stock.) #270-1413, 3,99 (2) "N" Battery Holder. (14 other styles in stock.) #270-405 . . 59C (3) Mini-Hook Adapters. Slip on test probe lips. #270-334, Pr.f2.59 (4) Micro-Hook Test Clips. #270-355 ..2.69 (1) Prewired Tem- perature Module. Just add one "AA" battery lor use as a thermometer. You can also connect simple circuits to control external indi- cators and devices al temperatures you set. (Data included.} Has W liquid crys- tal display and selectable Fahren- heit or Centigrade modes. Module is easily panel- mounted. #277-123 . . . 19.95 j <2> , V ! I" € oft v e> e> J?5.i?S i1) ^ • Portable Short- wave Antenna, Dramatically im- proves reception on worldband portables! Con- nector clips to tel- escoping rod an- tenna. Antenna wire extends up to 23 feet — and winds up on pocket-size reel for convenient storage, travel. #278-1374, B.95 (2) Sat of 100 Ce- ramic Disc Capaci- tors. A variely of popular styles and values al a bargain price. Ratings up to 1000 WVDC. Slock up 1 #272-601. Set 1,98 (3) Assortment of 20 Electrolytic Ca- pacitors. Miniature a n d submi n i types in a variety of values witn ratings to 50 WVDC. #272-802. Set (Jl 2011.98 -Radio /hack AMERICA'S TECHNOLOGY CIRCLE 78 ON FREE INFORMATION CARD 30 GERARD ROBIDOUX AND ROBERT DMITROCA* A LOGIC ANALYZER IS AN INVALUABLE tool for debugging complex dig- ital circuits. Not only can it sam- ple and store the state of a large number of digital signals, it can perform complex analysis on the signals to determine their timing and state relationships. The ac- quired data can be displayed on either a waveform screen or a state screen. With four different pull-down menus available, all the controls are right at your fin- gertips! The essence of all digital logic circuits is the simultaneous op- eration of many signal paths. As an example, consider a typical desktop personal computer, such as the IBM PC. In order for the micro- processor to write to a single byte of memory, it must as- sert 20 address lines. 8 data lines, and over a half-doz- en control lines. In total, over 34 signal paths must operate correctly and simul- taneously for the computer to func- tion properly. When a digital cir- cuit fails, it becomes very difficult to de- bug. Traditional di- agnostic tools, such as the oscilloscope, can usually monitor 4 channels at the most. Other tools, such as logic probes, can only display the current state of a signal, and cannot be used to with time. Those problems led to the de- velopment of the logic analyzer. At its most primitive level, the logic analyzer may be considered to be an oscilloscope with a large number of channels, except that only the high-low state of a signal may be seen, rather than a con- tinuous analog waveform. Com- mercial logic analyzers typically have 16 to 300 channels. "Gerard Robidoux and Robert Dmitroca are partners in Convention Systems, a software Troubleshooting digital circuits is a cinch with this 16-channet f 50MHz logic analyzer. COMVENTION SYSTEMS BEBBgHBEIW BM I 1fWW!rn M RflnVWg1fffl* | AOCU ~^ - | DDIREH _Ij74*CTeej llC29-^ JLJ74HCT02. 32 nals and determine their logic level. All logic families have a de- fined high and low level. For ex- ample, the TTL logic family de- fines a low as a voltage between and 0. 8 volts, and a high between 2.4 and 5.0 volts. Some logic ana- lyzers have a variable voltage- threshold, which allows you to define the high and low voltage levels depending on your par- ticular application. The logic analyzer that we pres- ent here recognizes only TTL and 5-volt CMOS levels. Since the vast majority of digital logic is de- signed with those two families, that's not a serious limitation, and it also eliminates the need for expensive high-speed voltage comparators. After voltage comparison, the signals entering the logic ana- lyzer are sampled by the input latches. Digital storage scopes (DSO's) use the same sampling technique. The sampling rate is determined by an internal time- base, or from an external clock input. The sampling rate is usu- ally adjustable in a 1-2-5 se- quence from a very high frequen- cy to a very low frequency (a few hundred MHz to less than 100 Hz). With a very fast clock, you can see the operation of the circuit in great detail for a very short period of time. With a slow clock you can see the operation of a circuit for a longer time, but with less ac- curacy. If you were debugging a high speed digital circuit, such as a microprocessor, you would use a very fast clock. A slower clock would be used to trou- bleshoot a very slow circuit, such as a 1200-baud serial interface. The external clock input is used when you want the sam- pling rate to be controlled by an external circuit. A good example of that is when you attach a logic analyzer to the data and address CHJHflTION OOLINrEH P-QD-1 BDf_.7l lines of a microprocessor to trace program execution. The logic analyzers external clock line is connected to a memory strobe line, such as as* (68000 family) or ale 7 (8088 family). The logic analyzer would then capture the status of the processor at each bus cycle. After being captured by the in- put latches, the input signal data flows to two places; the high speed RAM and the trigger logic. Let's take a close look at the trig- ger logic first. In most digital designs, we're interested in the operation of the circuit at a very specific point. The action of the trigger logic al- lows us to obtain only that range of data in which we are inter- ested. For each of the signals being monitored, we can specify a trigger pattern of high, low, or "don't care" (either high or low). When the logic analyzer is en- abled, it will continuously sam- ple the input data lines until the trigger pattern is recognized. At that point, sampling will either stop, or continue for a preset number of samples. That feature lets us see the state of the signals occurring before, or, perhaps, both after the trigger point. The high speed static RAM stores the values of the input channels being monitored. That RAM is often known as the ac- quisition data buffer, since it provides a storage space for the data being acquired from the input data lines. Notice that a logic ana- lyzer, unlike an os- cilloscope, is not a "real- time" device. An os- cilloscope can immediately and continuously shows the voltage at the probe. The logic analyzer, on the other hand, stores the sig- nal data until a trigger pat- tern is recognized. The FIG. 2— INPUT BUFFERS AND TRIGGER LOGIC. The input pod contains 16 data-channel Inputs, an external clock input and a ground connection. The input data enters resistor arrays RA1 and RA2, and into latches IC1 and IC11. The acquired data is routed into the trigger logic and to the high-speed RAM. CO CO 33 AD (0..15) IC5 CY7C128A w o z o cc G w _i w O Q < < LOAD c CLR !C27 74ACTK3 A QA B QS C QC D QD ENP RCO ENT CLK < LOAD < CLR AO 1/01 A1 MK A2 1/03 A3 \m A4 I--D5 A5 1/06 A6 t/07 A7 1/08 AS A9 A10 CE OE wt ffflS CY7C1 AO 1/01 A1 1/02 A2 1/03 A3 1/04 A4 uos AS 1/06 A6 1/07 A7 1/08 AS A9 AJO CE OE WE AO(0..15) ADO AOI AD2 AP3 / js±y ADS / AD6 AD7 AD8 / 10 AD9 / 11 AD13v 13 AD11 / 14 AOI?/ 15 AD13/ 16 AD14/ 17 APIS/ bo)o,7) y ADO API ADZ ADS \ AD4 ADS AD6 s AD7 \ /PCS4 > - AFJ8 AM AO10 AD13 AD14 AD15 | /pcrs a A1 A2 A3 A4 A5 A$ A7 AS G DIR BOO BD1 BE>2 BD3 BD5 BDB BD7 IC16 74HCT245 19, A1 A2 A3 A4 AS AS A7 AS •4 G DIR BDO 17 BDI , 16 BD2 , 15 BD3 , 14 BD4 , 13 BDf] , 12 BD6 , 11 B07 , IC28-a V; T4ACT74 D CLK PR OVER > AOCLK IC79-d '•< 74ACTO IC22 74ACT183 <£ - ^ /STCLK A OA 4K C D ENP ENT CLK ■cJLOAD <■ CLR QC QD RCO IC31-S V< 74F32 IC23 74ACT163 IC2S-& 10 1 '/I 74ACT74 C D ENP ENT CLK 4 LOAD CLR 14 13 iF uu-^ RCO I TRIGGER \-^- CLK — CL PR D Q 15 /STCLK ^ IC24 74ACT1B3 A B C D ENP ENT CLK LOAD CLR QA QB QC QD RCO AQRESET t — | strig y AQSTART TRGTVPEO TRGTYPE1 STEP Ml I 'W.*,. END 9 1029-b l/i 74ACT02 — < ^ STCLK ] IC29-C Vl 74ACT02 <3 X S1EP | <^= X CCLR | FIG. 3— THE ACQUISITION SECTION, consisting of high-speed RAM storage and control logic, is the heart of the logic analyzer. 34 signal data is shown only after that has occurred. The last section of the logic analyzer is the user interface, which consists of a keyboard and display that are built right into the unit. Circuit description Now that we've looked at the block diagram of the logic ana- lyzer, we'll turn our attention to how the unit operates. The sche- matic in Fig. 2 shows the input pod and trigger logic. The input pod connector, Jl, contains 16 data-channel inputs, the exter- nal clock input and the ground lead connection. It also carries other signals that can be used by external pods. The data to be sampled goes into Jl, through resistor arrays RA1 and RA2, and into latches IC1 and IC11. The level of each channel is latched using the Ag— clk signal (the sampling clock). Pull-up resistors RA1 and RA2 drive the inputs of the latches high if nothing is connected to the input. The acquired data (AD[0.. 15]) is routed to the trigger logic and to the high speed RAM storage [Fig. 3). The trigger condition of the in- put data may be set to high, low, or "don't care." The "don't care" circuits for the first eight inputs are formed from IC2, IC3, and IC7, and the last eight inputs from IC12, 1013, and IC17. If an input is set to a "don't care" con- dition, the input of the corre- sponding nand gate is set low. That forces the output to be high regardless of the input from the data latch. If the nand input is set low, the data is simply inverted. The outputs from the nand gates are presented to the eight- bit comparators, IC4 and IC14. The output of those IC's (pin 19) goes low whenever the p and q inputs match. Masking of IC8 and IC18 latches is performed by the fol- lowing technique. If the trigger bit to either IC is low, a high is written to the latch. Similarly, if the trigger bit is high, a low is written. For "don't care" condi- tions, a high value must be writ- ten, since we have forced the p input to high (by disabling the nand gate). The upper and lower trigger outputs of IC29-a forms an active-high trigger output. PARTS LIST All resistors are ft-watt, 5%, unless otherwise indicated. R1-RS-10,000 Ohms R9 — 470 ohms R10 — ohms, or jumper wire RA1, RA2— 1 megohm, 10-pin bussed SIP resistor array Capacitors C1-C11, C13-C20, C23, C25, C27-C38. C40-C49, C58-C60— 0.1 (tF, ceramic axial C12. C24— 3.3 (jlF, 10-voit tantalum C21. C22— 10 pF, ceramic disc C26— 100 h-F, 25-volt tantalum C39 — 50 pF, ceramic disc C50-C57— 22 nF electrolytic Semiconductors IC1, IC11— 74ACT574 8-bit latch IC2, IC3, IC12, IC13— 74ACT00 quad 2- input nand gate IC4, IC14— 74ACT521 8-bit comparator IC5. IC1 5— C Y7C128A 2K x 8 1 5-ns static RAM (SRAM) IC6, SC16— 74HCT245 octal transceivers 1C7-IC9. IC17. IC18, IC39— 74HCT5748- bit latch IC10— 74F85 4-bit comparator IC19, IC22-IC27— 74ACT163 4-bit coun- ter IC20— 74HCT138 3-to-8 demultiplexer IC21— TL7705A voltage supervisor and reset control IC28— 74ACT74 dual D-type flip-flop IC29— 74ACT02 quad 2-input NOR gate IC30— V25 high-integration micro- processor 1C31— 74F32 quad 2-input OR gate IC32— 74ACT86 quad 2-input xor gate IC33— 74F160 4-bit counter IC34— 74ACT153 dual 4-to-1 mulitplexer IC35-IC37— 74LS390 dual bi-quinary counter IC38— 74ACT151 8-to-1 mutiplexer IC40— Dallas Semiconductor DS1213C "Smart Socket" and 32Kx8 100-ns SRAM or Dallas Semiconductor The minimum trigger-dura- tion circuit is made from ICQ, IC19, and IC10. That circuit en- sures that the trigger is present for a minimum amount of time before the trigger pattern is actu- ally recognized, which prevents glitches from causing a false trig- gering to occur. The desired trigger-duration count is contained in the latch of IC9. Whenever the trigger pat- tern occurs, 4-bit counter IC19 is enabled. That counter runs at 50 MHz (20 ns per count). When the desired duration count and the counter value match, the trigger output (pin 6 of IC10) will go high, indicating that a valid trig- DS1235 integrated battery backed RAM IC41, IC42— MAX232 RS-232 tranceiver and charge pump IC43— 7805 5-volt regulator IC44— GAL16V8-15LP PLD IC45— GAL16V8-10LP PLD IC46— 128K x 8 250-ns EPROM LCD panel— Sharp part no. LM24014W Other components XTAL1— 16-MHz HC-49 crystal XTAL2— 20-MHz 14-pin DIP package os- cillator XTAL3— 50-MHz 14-pin DIP package os- cillator Case— Pactec CM69-120 Key switches (12)— 75120-OQ2'0000 AC adapter — 9 VDC at 1 amp secondary output Connectors J 1— Right- angle DB37 connector P2-P4 — 3-pin socket strip J3 — Right-angle DBS connector J4 — 20- pin socket strip (2x10) PI — 7-pin socket strip (1 x 7) J2 — Power connector (2 .3- mm barret) Keyboard— 7 x 1 row- header Acquisition clip — DB37 connector with 18 wires and micro-clips. P1 — 2 x 10 row-header connector for LCD panel Sockets 20-pin machined sockets tor IC1 and IC1 1 32-pin socket (or IC46 14-pin machined socket for IC32 84-pin PLCC socket for IC30 Hardware 4 %-inch standoffs with 4-40 internal thread 4 %-inch standoffs with 4-40 internal thread 18 4-40 screws with pan head, Vi-ineh length 2 4-40 nuts 1 TO-3 heatsink and heatsink grease ger pattern has been recognized. If the trigger disappears before the desired duration count has been reached, the counter is cleared. It will start over when the trigger becomes valid again. The circuit shown in Fig. 3 contains the heart of the logic analyzer: the high speed RAM storage and the control logic. Data for the lower eight channels is stored in IC5, while IC15 stores the data for the upper eight chan- nels. Both IC5 and IC15 are 2Kx8 15-nsSRAMS. An 11-bit binary counter is formed from IC25, IC26 and IC27. That counter drives the ad- dress inputs of the RAM IC's. The c Z m io to 3J address is incremented by 1 for each cycle of the aq— clock {acquisition clock) signal. The trig function lets you specify the position of the trigger position within the acquisition data buffer. When pre is selected, the trigger is set at the start of the buffer. When the trigger con- dition is met, data is sampled un- til the entire acquisition buffer is filled. In the mid trigger mode, the trigger point is set at the middle of the data buffer. The first half of the buffer may or may not con- tain data that was sampled be- fore the trigger point. In the post trigger mode, storage of data will stop immediately after the trigger condition is recognized. An 11-bit binary counter is formed from IC22, IC23, and IC24. That counter holds the cur- rent position within the acquisi- tion data buffer. The position counter is reset whenever the trigger condition is recognized, after which it is incremented by 1 for each cycle of the acj — clock signal. The acquisition section control is formed by IC45, IC29, and portions of IC28 and IC31. The trigger output from IC10 to a constant high level (strig) is con- verted by IC28-D. A finite state machine, IC45, coordinates the signals coming in from the mi- croprocessor, trigger logic, and position counters, and generates the appropriate outputs to con- trol the acquisition cycle. trgtypeo and trgtypei are used to inform the state machine where the trigger should be posi- tioned in the acquisition buffer (for example, they set the pre, mid, or post modes), aqstart tells the logic analyzer to begin look- ing for the trigger condition, and to start storing data into the ac- quisition buffer. The midway and end signals from the position counters tell the state machine how much bLiffer has been filled since the trigger. When a trigger has been recog- nized and the acquisition buffer filled up, the state machine will assert the into line, informing the microprocessor that acquisi- tion data is now available. The step, cclr, and ddir— en CO o z o tr F o LU _l W 6 D < DC CTAL3 50MHz OSC GND OUT ^ * V !U 7 s ■i XTAL2 20MHz OSC GND OUT u A D C D ENP ENT CLK LOAD IC33 74F160 QA On QC QD RCO CLR POD CLK > IC32-b V* 74ACTB6 TO^ 10 12 13 ICO 1C1 1C2 1C3 2C0 2C1 2C2 2C3 1G 2G IC34 74ACT153 14 SEL5 ^ BD(Q.J) \BD0_ V.BQ1 vJj02_ vBD3_ BD4 ^BD5 1BD68 \BUT_ /PCS6 > 11 JM 01 02 03 D4 D5 D6 D7 D8 >CLK OC IC39 74HCT574 Q7 Oft 19 SEL0 16 SEH 15 SEL2 14 SEL3 13 SEW 12 SEL5 \ ■-0 CKA -ic CK3 !C35-a Va 74LS390 CLR QA OH 0C QD ["J 12* 14 CKA CKB IC35-b Vi 74tS390 CLR QD QA QB QC 5 CKA CKB QA QB QC IC36-a '/2 74LS390 CLR QCf 12 14 CKA CKB IC36-b V: 74LS39D CLR QD QA QB ,QC Ej CKA CKB IC37-3 Vj74LS39B CLR QD QA QB ,QC 5 12. 14 CKA CKB IC37-b 0 — l— C37 0.1 045 •0.1 C42 '0.1 Ct 0.1 C2 0.1 G3 0.1 C4 0.1 55 _L .. 1.1 T" 0.1 032 C6 0.1 07 0.1 044 0.1 019 0.1 018 ' 0.1 -L 017 *T* 0.1 C16 ' 0.1 C15 0. _L C14 C13 _L 060 _l_ i.1 T* 0.1 "T o.i "T C13 0.1 060 0.1 C41 0.1 020 0.1 09 0.1 __ 051 I 1 01 0.1 028 0.1 030 0.1 G31 0.1 ^ o.i *f o.i *r C29 1 C34 J.C40 0.1 T 0.1 _LC33 __C23 __C58 -L C35 J. C36 _L 010 __C59 J. C27 ,, C8 T" o.i "-o.-t '"o.i To.1 T* o.i T o.i '"tn T o.i T 0.1 DECOUPLING CAPACITORS FIG. 6— POWER CIRCUIT AND DECOUPLING CAPACITORS. Each IC is decoupled by a 0.1 ,i.f capacitor. A divider chain, which pro- duces the 22 clock frequencies, is formed by IC33, 1C34, IC35, IC36, andlC37. Multiplexer IC34 selects the 50-MHz or 20-MHz os- cillators, the 25-MHz or 5-MHz signals from IC33, or the external k line. A bi-quinary divider chain is formed by IC33, IC35, IC36, and IC37. IC33, a 74ACT160, is similar in function to IC35-IC37, which are 74LS390 dual-decade counters. It is used at the begin- ning of the chain because the 74LS390 can handle a maximum frequency of only 20 MHz. The various clock sources are multiplexed into IC38, an 8-to-l multiplexer. The stclk (state clock) signal is produced by IC38, That signal is used to drive the acquisition state machine and to sample the input data lines. Eight-bit latch, IC39, is used to select the source and/or frequen- cy of the stclk signal. The external clock enters pin 4 of IC32-b, an xor gate. By setting pin 5 to a high level, the clock signal can be inverted before being presented to the multiplex- ers. To sample on the rising edge of the external clock, pin 5 is set to 0. To sample on the falling edge, pin 5 is set to 1, The microprocessor, keyboard interface, LCD panel interface, serial interface, RAM and ROM is shown in Fig. 5. The micro- processor used is the V25 (IC30) from NEC electronics, which is 100% code compatible with the Intel 8088 microprocessor (used in the IBM XT class of comput- ers). The V25 includes two serial channels, a DMA controller, and parallel I/O ports. Using this part allowed us to implement the en- tire microprocessor section using only seven IC's! There is one ROM site, IC46, and one RAM site. IC40. The ROM site is a 32-pin JEDEC socket which will accept 1-, 2-, or 4-Mbit EPROMS. The logic ana- lyzer software currently fits in a 1 Mbit part (128Kx8). The RAM site accepts either 32K or 128K static RAM IC's. In order to per- manently store the configuration of the logic analyzer, the RAM site uses a Dallas semiconductor component called a SmartSocket. That device con- sists of a standard socket, along with a 3-voft lithium battery, and continued on page 87 This solid-state electronic compass uses Hall-effect sensors to keep you heading in the right direction. ANTHONY J. CARISTI MOST OF US HAVE AT ONE TIME OR another used a common magnet- ic compass, which often consists of a light-weight balanced mag- net suspended on a pivot. The magnet, free to rotate, is affected by Earths magnetic field, and as- sumes a position in which its north-seeking pole points to Ear- th's magnetic north pole. The geographical north pole of Earth is offset from the magnetic north pole by about 10 or 15 degrees in most areas of the United States. Many low- cost compasses leave something to be desired in their performance, which can be af- fected by any tilt of the case or friction in the pivot. However, with the development of solid- state magnetic detecting devices, called Hall-effect generators, it is possible to construct a low-cost, reliable magnetic compass which has no moving parts and elimi- nates the disadvantages of inex- pensive mechanical types. Be- cause the project contains no moving or mechanically sensitive parts, it is an extremely rugged device that can tolerate all poten- tial stresses encountered when hiking or traveling through rough terrain. Taking a reading on the compass is quick, easy, and very reliable. This solid-state compass uses a unique detection system that produces two sharply defined points centered on the direction of magnetic north, as indicated by an LED. That permits a quick, accurate reading. The project, housed in a plastic enclosure, is small and lightweight, and is powered by a common 9-volt bat- tery. Since the compass circuit is energized only when it is used to take a reading, the battery's useful life approaches that of its shelf life. AN ELECTRONIC COMPASS About the circuit Development of a magnetically sensitive solid-state compass is made possible through a phe- nomenon called Hall effect, which was discovered in 1879 by Edwin Hall: he observed that a small voltage was developed at the edges of a cur rent- carrying gold foil when the foil was ex- posed to a magnetic field. Solid- state technology now provides small, low-cost Hall-effect de- vices, which are very sensitive and able to detect Earth's ex- tremely weak magnetic field. The basic Hall-effect sensor, shown in Fig. Lisa small sheet of semiconductor material in which a bias current flows. The Hall- effect output of the sensor takes the form of a voltage measured across the width of the con- ducting material, and will be neg- ligible in the absence of a magnetic field. If the biased Hall sensor is placed in a magnetic field with the flux at right angles to the flow of current, a voltage output directly proportional to the intensity of the magnetic field is produced. Additionally, the voltage will be a function of the angle between the lines of force and the plane of the sensor. Max- imum Hall-effect output voltage occurs when the face of the sen- sor is at right angles to the lines of force, and zero voltage is pro- duced when the lines of force are parallel to the face of the sensor. The Hall-effect sensor is fur- ther enhanced by using inte- grated-circuit technology to add a stable high-quality DC ampli- fier to the device. It then provides a usable linear output voltage which is sensitive enough to re- act to Earth's magnetic field (about Vi Gauss). Referring to the schematic in Fig. 2, The Hall-effect generators (IC3 and IC4) are three-terminal linear devices which are driven by a regulated 5-volt supply pro- vided by fixed-voltage regulator IC1. The output of each of the sensors is a DC voltage that var- ies linearly from a quiescent val- ue of 2.5 volts as their position with respect to the lines of force of the magnetic field changes. A typical sensor has an output- voltage sensitivity of about 1.3 millivolts per Gauss. Two Hall-effect generators are used in the circuit to provide CO o o en ■<- o LU O Q < DC BIAS CURREN1 SEMICONDUCTOR MATERIAL / VOLTMETER U-X] PMAGNETIC J LINES OF FORCE FiG. 1— THE BASIC HALL-EFFECT sensor is a small sheet of semiconductor material in which a bias current flows. The output voltage, measured across the width of the conducting material, is negligible in the absence of a magnetic field. If placed in a magnetic field, the output is directly pro- portional to the intensity of the magnetic field. R6 475K --VirV-+ FIG, 2— TWO HALL-EFFECT GENERATORS provide twice the sensitivity of a single sensor. The two devices are physically oriented in opposite directions so that the change in output voltage of one sensor will be positive while that of the other will be negative as the compass is rotated. twice the sensitivity of a single sensor. The two devices are ori- ented in opposite directions so that the change in output voltage of one sensor will be positive while the change in the other will be negative as the compass is ro- tated. The voltage differential be- tween the two output terminals of the sensors is a representation of the magnetic field intensity and direction. The voltage dif- ferential produced by the Hall generators is fed to a differential amplifier, IC2-a. As a result, the output of IC2-a (pin 1) will be a minimum (null) when the com- pass is facing the magnetic north pole, and a maximum when it faces the south pole. The change in output voltage of IC2-a is too small to allow a simple method of determining the null voltage as the compass is rotated. Therefore, IC2-b is used as an inverting amplifier with a gain of 100 to further increase the change in voltage. A DC off- set, provided by sensitivity-ad- just potentiometer R9 and volt- age follower IC2-C, permits the DC output voltage of IC2-b to be set to a usable level to drive the next stage. Op-amp IC2-d is used as a volt- age comparator with a fixed refer- ence of about 3.4 volts fed to its negative input. Thus, when the output of IC2-b fed to the positive input of the comparator exceeds the 3.4-volt reference level, the output of IC2-d (pin 14) goes high, applying forward bias to Ql. That in turn illuminates LED1 to indicate that a voltage exceeding the reference exists at IC2-b pin 7. The use of a voltage comparator to detect the change in output voltage of IC2-b (pin 7) produces two sharply defined points and allows a more accu- rate determination of the mag- netic north pole. As shown in Fig. 3, the LED will be illuminated over a small arc as the compass is rotated full circle, and will remain off over the rest of the 360-degree span. The sensitivity control (R9) al- lows adjustment of the width of NORTH POLE SWITCHOVER POINT | SWITCHOVER POINT FIG. 3— THE LED WILL BE ILLUMINATED over a small arc as the compass is rotated full circle. True magnetic north is the posi- tion at the center of the arc. 40 the arc. Once the two LED switching points are determined, true magnetic north is then die position at the center of the arc. Power is provided by a common 9-volt battery. The circuit draws about 25 mA and, since it's usu- ally powered for only a few sec- onds at a time, battery life is extremely long; several hours of continuous compass operation is also possible. Circuit stability with a falling battery voltage is ensured by the 5-volt regulator, IC5. When the battery is ex- hausted and cannot deliver suffi- cient current to operate the circuit, the LED will appear dim or will not illuminate at all. Construction The circuit, when built on the printed circuit board (for which we have provided the foil pat- tern), is very compact; the pro- totype is housed in a 2 I /2-inch square by 1-inch high plastic en- closure, that has sufficient room to accommodate both the board and the 9-volt battery. A metal en- closure must not be used for this project — it can attenuate or dis- tort Earth's weak magnetic field. The power switch and sensitivity control are mounted on the side of the enclosure to allow easy op- eration of the compass. Figure 4 shows the parts layout. The position of all polar- ized components (especially the Hall sensors) must be followed exacdy as shown. The operation of the project depends upon the Hall generators being placed in opposite directions and exactly parallel as indicated in Fig. 4. Note that the orientation of the sensors is determined by the marked face of the device, with pin 1 being on the left side when looking at the markings. The sensors must be positioned so that they are aligned square with the rectangular shape of the printed circuit board. That way the compass direction will be accurate when the project is as- sembled into the enclosure. (Use the "north" indication of Fig. 4 to determine the relationship be- tween the PC board and compass scale when final assembly is done.) Many of the resistors specified in the parts list are metal-film types. The use of such compo- nents ensures maximum sta- FIG. 4— PARTS PLACEMENT DIAGRAM. The Hall generators must be placed in opposite directions and exactly parallel as shown. Pin 1 of the Hall sensors is on the left side when looking at the markings on the face of the device. PARTS LIST All resistors are Vo-watt, 5%, un- less otherwise noted. R1, R2-^750 ohms, 1% metal film R3, R4, R1 2— 100,000 ohms, 1% metal film R5, R7, R1 1—47,500 ohms, 1% metal film R6-^75,000 ohms, 1% metal film R8, R10— 249,000 ohms, 1% metal film R9— 5Q,00Q-ohm, potentiometer R13— 47,000 ohms R14— 560 ohms Capacitors C1-C3— 0.1 ^F, 50 volts, ceramic disc C4 — 0.01 fjtF, 50 volts, ceramic disc Semiconductors IC1— AN78L05 5-voit regulator IC2, IC3— Sprague UGN3503U Half generator IC4— LM324N quad op-amp LED1 — red light-emitting diode Qf— 2N3904 NPN transistor Other components B1 — 9-volt alkaline battery S1 — SPST pushbutton switch, nor- mally open Miscellaneous: Plastic enclosure, battery clip control knob, IC sock- et, wire, solder, etc. Note: The following items are available from A. Caristi, 69 White Pond Road, Waldwick, NJ 07463: An etched and drilled PC board, $9.95; set of two Hall sen- sors, $9.75; IC1, $2.00; IC2, $2.00; set of 11 metal-film re- sistors, $4.95. Please add $2.50 postage/handling. bility of the circuit with varying ambient temperature changes, and reduces the need to periodically adjust the sensitivity control. Ordinary carbon re- sistors are not temperature-sta- ble and should not be used in place of metal-film types. Also, it's a good idea to use a socket for IC2. It is recommended that you use a miniature momentary push- button switch for SI. That will ensure that battery power will never be inadvertently left on when the project is not in use. The sensitivity control, R9, may be placed on the side of the en- closure to allow circuit adjust- ment when necessary. You should use a battery clip for Bl. If desired, a suitable clip can be ob- tained from a discarded 9-volt battery (just peel away the metal case and rip the top off). Be very careful to wire the battery clip with the correct polarity. When the circuit board is com- pleted, examine it very carefully for shorts, opens, and cold solder joints. It is much easier to correct problems at this stage rather than later on if you discover that your project does not operate. A photo of the finished board is shown in Fig. 5. Use a photocopy of the artwork in Fig. 6 for the top of the com- pass: you can simply glue it in place. Indicator LED1 is placed at the north indication of the com- pass by drilling a suitable size hole in the plastic top where the letter N would be. Be very careful when drilling; some plastics will shatter if subjected to excessive stress. Be sure to properly orient the top of the enclosure in accor- dance with the final position of the PC board. c Checkout } When you are satisfied that all j wiring is complete and correct, t m g z o cc I- b LU _J LU 6 O < (2 the checkout procedure must be performed, and be sure to use a fresh 9-volt battery. Checkout re- quires a DC voltmeter connected to ground and the output termi- nal of IC1. Apply power to the cir- cuit check for +4.75 to +5.25 volts. Measure the resistance be- tween the 5-volt bus and ground; a normal reading is about 600 ohms. Measure the terminal volt- age of the battery to be sure that it is delivering at least 7 volts un- der load to IC1. Replace a weak battery if necessary. Next, measure the output volt- age of IC2 pin 1, and verify the voltage range of potentiometer R9. (Compass orientation is not important at this time.) The volt- age should be about 2 to 3 volts DC. Measure and record the DC voltage that you observe at IC2-a pin 1, Measure the voltage change at IC2-c pin 8 as the sensitivity con- trol is rotated over its entire range. The difference between the highest and lowest readings should be about 0.45 volts. Ide- ally the center of the measured voltage range should be close to the voltage recorded earlier at IC2 pin 1. If necessary, change the value of R8 and/or RIO so that the volt- age range obtained at IC2-C pin 8 is somewhat centered about the voltage reading at IC2-a pin 1. This ensures proper adjustment range of the sensitivity control for the particular pair of Hall gen- erators that are used in your compass project. Once the sensitivity range is correct, rotate R9 over its range while observing the LED. At one end of the setting, the LED should be extinguished, and at the other end it should be illumi- nated; if not, check the polarity of LED1 and the orientation of Ql. Check pin 14 of IC2-d to be cer- tain it swings from about zero to battery voltage as R9 is rotated over its range. Check pin 13 of IC2-d for a voltage of about 3.4 volts as set by Rll and R12. Prob- lems in this area may warrant re- placing IC2 if everything else checks out alright — check your soldering before changing the IC. When the LED operates as de- scribed, the project is ready to be tested under actual operating conditions. Before you start, make sure that there are no mag- F1G. 5— EXAMINE THE COMPLETED board for shorts, opens, and cold solder joints before installing it in a plastic case. FIG, 6— USE A PHOTOCOPY of this art- work for the top of the compass, and glue it in place on top of the case. 11 l_ J_L FOIL PATTERN for the electronic com- pass, shown actual size. netic fields nearby, and the proj- ect is not shielded by a large mass of iron or steel. While holding the unit hori- zontally in any direction, apply power and carefully adjust R9 so that the LED is at the switch-over point between on and off; allow at least 10 seconds for the circuit to stabilize. Flicker of the LED is normal as the circuit switches back and forth. Once R9 is set, rotate die compass over a 360- degree arc (full circle) and note that the LED will be on over part of the arc, and off over the rest. If necessary, readjust potentiome- ter R9 very slightly to obtain this result. The optimum setting for R9 will be at the point where the arc of illumination is as small as possible. As the compass is rotated over the illuminated arc, note the two on/off points. When the compass is positioned halfway between those points, it is facing the mag- netic north pole, and the scale indications on its face indicate all other directions. Using the compass Always be sure that the battery is reasonably fresh, and take along an extra one before start- ing out on an excursion with the compass. (A weak battery will be indicated by a dim or totally unlit LED.) Avoid taking a compass reading in any area where there may be a magnetic field from a nearby device, or where Earth's magnetic field is shielded by a large mass of metal. Hold the compass in a horizon- tal position and rotate it full cir- cle while observing the LED. Adjustment of the sensitivity control is indicated if the LED is totally on or totally off as the com- pass is rotated. Always allow at least 10 seconds operating time for the circuit to stabilize. Once the sensitivity control is ad- justed, it should not require read- justment unless the project is subjected to an extreme change in temperature. Don't forget that the electronic- compass circuit can be used for things other than a simple direc- tion finder. It provides an elec- tronic means of rinding north, so it should be easy to interface the compass to other devices that may need to know where north is — a robot, for example. R-E 42 NEW WORLD I i JOSEF BERNARD WHAT MICROPROCESSORS WERE IN the 1980's, digital signal process- ing (DSP) will be in the '90s. It is already being used 'in consumer audio, video, and communica- tions equipment, and will show, up in many more products within , the next few years. With the ability to design and manufacture fast and accurate analog-to-digital (A/D) and digital-to-analog (D/A) converters, and to process and manipulate digital information at blinding speed, todays tech- nology has made it as cost-effec- tive to manipulate signals in the digital realm as it is to do so in the analog, and the results are better, and- more spectacular. . / *. CO g z o a: t- o Before we can appreciate some of the devices in which DSP is being, and will be used, we should have an understanding of what it is, and how it works. Analog signal processing Signal processing can take many forms. Sometimes it in- volves changes in signal levels such as the type used in an audio graphic equalizer. In that type of device, the audio -frequency spec- trum is divided into frequency bands by a series of analog filter networks. The gain of each filter circuit can be adjusted upward or downward around a center point to emphasize or de-empha- size the audio frequencies for which it is responsible, and therefore tailor the sound of an audio system to fit the require- ments of a room or the ear of a listener. We'll return to the exam- ple of an audio equalizer later to show some of the effects that can be accomplished with DSP. Analog filters — either in the form of L-C networks (Fig. 1-a) or simple op-amp circuits (Fig. 1- b) — -are used in other numerous signal processing applications. They can, for example, be used to "peak up" audio or RF signals at certain frequencies or, in the form of high-pass, low-pass, and bandpass or notch filters, to al- low the passage of signals of cer- tain frequencies while blocking those of others. Signal processing can also be used to modify the phase rela- tionships in a complex signal, as is the case in the tint control found on NTSC TV receivers— al- though that's not being done dig- itally, at least not yet. In audio, on a gross scale, phase shifting shows up in the form of "phlang- ing," a technique used in record- ing studios to add a rather weird- sounding effect to material. (The technique got its name from the fact that, initially, it was pro- duced by playing two identical tapes and varying their speeds ever so slightly by applying pres- sure to the flanges of the tape reels. Now, of course, it's done digitally.) And, since the ear is ex- tremely sensitive to the phase re- lationships of the sounds reach- ing it and uses them to help establish the location of sound sources, changing those rela- tionships in recorded material fTPSTP-, r^WT\ r J HW\ FIG. 1— TWO FILTERS; a passive L-C (a) and an active op-amp (£>}. Neither of these types can be as flexible or reliable as one using DSP. 1001 r^£r4> FIG. 2— A HYPOTHETICAL DSP VOLUME CONTROL would divide each signal sample by the same number to reduce it in strength. can greatly affect the way the sound is perceived (see All About Surround Sound, June 1990 Ra- dio Electronics), Signals can also be summed, or subtracted from one other, to achieve particular results. Both summing and subtractive tech- niques are used, for instance, in various audio and video noise-re- duction schemes. Until recently, all the signal processing schemes described above, and a number of others not mentioned here, were carried out in the analog domain. De- pending on the degree of preci- sion required, the circuits could get very complex and very expen- sive. Also, a particular circuit could generally serve only a single purpose; if you wanted both fre- quency-selective processing, for example, and noise reduction, you had to design and build two completely different processing stages. Also adding to its incon- venience was analog signal-pro- cessing's dependence on analog components. As analog compo- nents heated and cooled, and as they aged, their values drifted and the characteristics of the cir- cuits in which they were used changed. Precision in the analog world can be extremely difficult and costly to come by. Digital sig- nal processing, however, is en- tirely different. Digital signal processing Once you have converted an analog signal to digital form — to a string of binary numbers repre- senting the voltage levels of the signal as it varies over time — you can very easily perform all sorts of operations on those numbers that will affect the signal they represent when they're recon- verted to analog form. Let's take a very simple exam- ple. Suppose you wanted a digital volume control, which might, under certain primitive circum- stances, be construed as a kind of DSP. To cut the volume of a signal in one third, all you would have to do would be to divide every binary number in its digital representation by three (Fig. 2). The voltages represented by the resulting numbers would be one third their original value, and the amplitude of the reconstructed analog signal would be one third that of what you started with. By changing the divisor, you could vary the amplitude accordingly in either direction. Taking the process a step fur- ther, if you were to multiply all the 44 28-BIT DIGITAL OUTPUT FIG. 3— A CD PLAYER'S DIGITAL FILTER is an example of a dedicated DSP IC. Within it, each sample is multiplied by a fixed coefficient; this is the basis for oversampling. numbers by one (the equivalent of a unity-gain amplifier) except for those representing frequen- cies between X and Y, which it would divide by, say, 8, you would have a notch filter. That par- ticular filter would, admittedly, have extremely steep sides, but its slope could be modified by using an expression of some complexity to determine the di- visor at each point. As another example of digital signal processing, consider a sig- nal that's stored briefly in RAM as it passes through a system. By reading out that signal a couple of milliseconds after it's been read in, or by shifting it slowly through the RAM's addresses, and then adding it back at a lower level (smaller numbers) than the original as it was read out, you'd develop a reverbera- tion effect. Note, by the way, that in that application there are two DSP processes going on at once: time delay and level control. Digital signal processing of the sort we've just described has been with us for a few years, at least in simple form. For exam- ple, digital delay lines have long been used in recording studios. Perhaps the most sophisticated "non-DSP" DSP circuitry is that found in the oversampling digital filters used in CD players (Fig. 3), where every binary number pass- ing through is multiplied by a fixed coefficient. The problem with such DSP devices to date — both single-chip ones and the ones requiring an entire boxful of components — is that they have been dedicated to a single-pur- pose. They've not been very flexi- ble, which has limited their usefulness. Speed, too, has fre- quently been a limiting factor. The DSP processes used to en- hance satellite photographs, for example, do not take place in real time; it is sometimes weeks be- fore the results are available. (Al- though much of that delay is no doubt due to the bureaucratic process and long periods of "standing on line.") Even so, as you've read this de- scription of the principles of DSP you may have said to yourself, "Hey, I'll bet I could teach my computer to do that ! Then I could do anything I wanted!" And you could, but there would be a hitch. Even today's '386 and '486 desk- top systems operating at 30 MHz or more are not fast enough to keep up with the heavy computa- tional overhead demanded by good DSP DSP as the term is gen- erally used today, requires that information appear at the output at the same rate it is supplied to the input. Today's small comput- ers would need a lot of help to meet that criterion. 50 megaflops Fortunately, that sort of help is available. Just as numeric coprocessors, such as the 80387, have lifted a lot of the number- M1PS, MOPS, FLOPS Clock speed is not necessarily an accu- rate indicator of how rapidly or efficiently a device performs. One processor running at, say, 20 MHz, may not have the throughput of another operating at only 12 MHz. The difference is largely that of the device's internal architecture, instruction set, and other built-in programming. For that reason, performance is often more accurately measured in terms of the number of instructions or math operations of which a device is capable in a given period of time. The term "MIPS" stands for million in- structions per second, and refers to the number of commands that can be ex- ecuted in that time. A 27- MHz Motorola DSPS6001 runs at the rate of about 13.5 MIPS, a 33.3-MHz DSP96002 at 16.65 MIPS. "MOPS," which stands for million oper- ations per second, is a more accurate measure of a processor's abilities, since a single instruction can be responsible for the simultaneous execution of several (six in the case of the 56001, up to ten for the 96002) operations at once. Such opera- tions can include those for math (add, multiply, subtract), for moving data inter- nally and to and from memory, for carrying out program instructions, and so forth. The 56001 can perform at the rate of 81 MOPS and the 96002, 165 MOPS, Finally, "megaFLOPS," or MFLOPS, stands for millions-of-FLOPS. or millions of floating-point math operations per sec- ond. Floating-point math, which uses ex- ponential notation, is used extensively in the complex calculations required by such applications as 3-D graphics and image processing. Fixed-point math, which is like the "integer math" used in early Apple computers, is much simpler, and cheaper, than floating point to implement and per- form and is what the 56001 uses. It is well suited, though, to audio processing where the calculations are not as involved as they can be for graphics. crunching burden from their as- sociated microprocessors (and speeded things up enormously in the process) there are now special number-crunching processors for DSP Those processors make DSP a real-time process — the modified signal comes out as quickly as it goes in. The dif- ference between the "old" DSP and the new is rather like that between taking your pictures down to the drugstore to be de- veloped and picking them up a week later, and owning a Polaroid 60 -second camera. What makes real-time DSP pos- sible is a new class of ICs from c companies such as Intel, m Motorola, and Texas Instru- st ments, not to mention a number 2 45 If) o z | i- o LJ _J LU 6 Q < of offshore manufacturers. Just as the architecture and instruc- tion sets of math coprocessors are created with a specific pur- pose in mind, these special pur- pose devices are tailored to the high-speed processing of the dig- ital equivalents of audible and visible information. While each manufacturer has his own idea of what a DSP device should do, and how it should do it, the gen- eral principles are the same — real-time manipulation of digital data representing analog phe- nomena. We'll look at two DSP IC's from Motorola representing the group. Motorola's DSP56001 is a "gen- eral purpose" fixed-point-math DSP IC that's found applications in a number of different types of devices. For example, it is an inte- gral part of Steve Jobs' NeXT computer, that literal "black box," serving to provide onboard data communications {modem and fax) and sound synthesis for such purposes as voice mail, voice-interactive programs, and high-fidelity, CD-quality audio. The 56001 is also incorporated in Cincinnati Microwaves" Escort radar detector where it differenti- ates between radar signals and other, unwanted, types of noise. At a price of $56. even in single- unit evaluation quantities, and maybe less by the time you read this, the DSP56001 is affordable enough to show up in a number of mass-produced general-mar- ket devices. Speed is essential to real-time signal processing, and the DSP56001's specifications dem- onstrate how it performs in that area. For instance, the processor runs at a speed of 27 MHz, with an instruction-cycle time of 74.1 nanoseconds (0.0000000741 seconds). In the time it takes to execute one of those cycles, a beam of light would travel about 73 feet! Other 56001 specs include • Word length of 24 bits, provid- ing a 144-dB dynamic range. • Capability to execute at 94.5 million instructions per second (MIPS). • Three complete and indepen- dent execution units capable of operating simultaneously and in parallel. • Triple-bus Harvard architec- ture. (Harvard architecture, used MOTOROLA'S DSP56001 digital signal processor contains three separate execu- tion units and uses a triple-bus architec- ture to facilitate data handling. THE DSP56001 at the heart of Cincinnati Microwave 's Escort radar detector in- creases its sensitivity by differentiating between radar signals and other types of microwave "noise." in some RISC processors, in- volves two separate buses; the 65001 has three.) • The ability to perform six sepa- rate operations simultaneously. The physical and electrical specifications of this Motorola DSP device are impressive, both in terms of large and small num- bers as well. The DSP56001 • Comes in an 88-pin package. • Operates from a single 5 -volt supply. • Has five 5-volt and seven ground pins to ensure even power distribution and glitch- free operation. • Consumes less than half a watt of power. An even more powerful, al- though somewhat more spe- cialized, DSP device is Motorola's DSP96002 "Media Engine." This 32-bit device, whose internal ac- cumulators can store numbers 96 bits long, comes in a 223-pin PGA (pin grid array) package 1.845 inches square, and uses a one-micron architecture to ac- commodate some 850,000 tran- sistors. It operates at a clock speed of 33.3 MHz, although a "slow" 27-MHz version is also available. The processor can per- form at the rate of 50 megaFLOP's (see box copy), and even has ta- bles of sine and cosine values built into it, which can be used in areas such as graphics genera- tion and manipulation. The 96002 processor is capable of ad- dressing an incredible 12 gi- gabytes (12 trillion bytes) of memory. The DSP96002 is expected to find use in the new generation of entertainment and information- processing systems to provide high-resolution graphics and synthesized stereo sound. It has the capability to do both at the same time (hence the reference to it as a "multi media" product), switching back and forth be- tween the two tasks so quickly that no interruption is apparent. In medical, and other, imaging technologies DSP will prove itself invaluable in enhancing and ma- nipulating visual data. The Motorola IC is also expected to find application in color laser printers where it will convert page-description-language com- mands into the fonts and graph- ics that appear as output, and as controllers in huge high-end computer disk drives that re- quire constant compensation for the effects of thermal expansion and vibration. The science of robotics, too, will benefit from the ability of a processor such as the 96002 to perform powerful floating-point calculations in real time. For large and complex tasks, several 96002 s can easily be configured to operate in tan- dem and divide the work into more manageable slices, appor- tioning it among them. Motorola has plans to intro- duce an entire family of DSP products. One of the first is the 56ADC single-chip analog-to- digital converter. It can process signals at the rate of 6,4 million samples per second (Ms/s) (CD's, in comparison, use a sampling rate of 44.1 thousand samples per second), eliminating the need for complex sample-and- hold circuitry Also in the works is a "sawed off* 16-bit DSP device, as well as a 40-MHz version of the 32-bit 96002. Some real DSP products A very good example of some of the ways DSP will be showing up 46 in consumer electronics equip- ment is Sony's STR-D2010 stereo receiver. In it, many analog func- tions have been replaced by their digital equivalents, and in imple- menting those Sony has added an extra degree of flexibility to the features available to the user. A proprietary DSP IC, coupled with 16-bit A/D and 18-bit D/A cir- cuitry and an 8x oversampling digital filter (which, as we've pointed out, in itself provides a form of DSP) is firmware-pro- grammed for a number of useful operations. The receiver has no treble or bass controls. Instead, it con- tains a parametric equalizer to tailor frequency response. Pa- rametric equalizers used to be pretty tricky to design and use. They differ from "ordinary" graphic-style equalizers in that the frequency bands on which they operate, and their response curves within those bands, are adjustable to suit the needs of the user. The device's parameters of operation can be changed by the user. With its DSP IC (and 256K of on-chip RAM) the STR-D2010 allows you to define three sepa- rate frequency bands (a vacuum- fluorescent display allows you see the response curves, and also functions as a spectrum -monitor display), each with its own de- gree of boost or cut, and with one of several slopes. There's no "loudness" control either. In- stead, a digital signal-compres- sion technique is used to compensate for the way the ear perceives sound at low volume levels. The Sony unit also has sur- round-sound capabilities, and FIG. 4— A DIGITAL MICROPHONE, known as the DM-N from Ariel Corporation uses two Motorola A/D converters to provide two channels of digital Input to the NeXT computer system. It operates at the rate of 6.5 Ms s. eliminating the need tor sample- and-hold and anti-aliasing-filter func- tions. IN'jINI wmm L ACTIVE ONE'" OSP FIG. 5— USING DSP NOISE-CANCELLATION, this "stealth" muffler not only quiets engine noise, but improves performance up to fifteen percent by doing away with conventional baffle systems. uses DSP techniques to provide the various signal delays used to manufacture ambience through artificial echo and reverberation. There's Dolby Surround process- ing too, using digital techniques to extract the matrixed surround information from the left and right-channel audio signals. An autosound receiver from Eclipse includes DSP technology to provide ambience and other effects. Video, too, can benefit from DSP, although the term is generally not yet applied to the processes being used. Video noise reduction, for example, can be accomplished by digitizing the video and comparing suc- cessive pixels or adjacent lines. By pixel or line averaging, or even replacing a "bad" pixel with a "good" one, picture quality can be improved. It is even possible to average two or more successive fields of video to smooth things out. Amateur radio is getting into the DSP act, too. Kenwood's top- of-the-line amateur transceiver, the TS-950SD, uses DSP in a number of ways to enhance in- coming and outgoing signals. The receiver section, for in- stance, includes such DSP fea- tures as a digital AF filter with user-variable characteristics. The transmitter uses digital techniques for speech compres- sion that increase average output power while keeping peak power output the same. It is also possi- ble for the waveshape of the sig- nal to be manipulated using DSP techniques to increase intel- ligibility. IC SOURCES The Motorola DSP96002 digital signal processing IC currently sells for about $750 in single- unit evaluation quantities, $650 for the "slow" 27-MHz version. More information on this and the company's other DSP products is available from: Motorola Microprocessor Products Group DSP Marketing 6501 William Cannon Drive West Austin, TX 78735-8598 One supplier of complete sets of pre- programmed DSP iC's is: The DSP Group, Inc. 1900 Powell Street, Suite 1120 Emeryville, CA 94608 The manufacturer of the DM-N digital microphone and MM-96 multimedia board for MS-DOS computers, can be reached at: Ariel Corporation 433 River Road Highland Park, NJ 08904 Finally, the company that has de- veloped the DSP "stealth" muffler is: Active Noise & Vibration Technology 3811 E. Wier Avenue Phoenix, AZ 85040 On the cutting edge Besides the applications we've already mentioned, DSP is now being used commercially in such devices as cellular telephones for compansion; in phone-answer- ing and cordless-phone equip- ment for speech digitization, synthesis, and storage; in tran- scription and dictation units for { variable-speed playback; and in f facsimile machines and other de- ; continued on page 53 ( . en O 1 _l tu O D < We are in the process of building an automated component inspection system (CIS). Last time we built a PC- based capacitance meter. Now we will combine the capacitance meter with a volt/ohmmeter on a single PC board. The result will be an accurate, low cost, comput- er-assisted test instrument that interfaces through a standard PC parallel port. Our CIS meter measures three basic quantities: resistance, volt- age, and capacitance. Resistance may vary from to 20 megohms. Voltage may vary from to 2 volts DC, but simple peripheral cir- cuitry can be added to increase range. Capacitance may vary from 20 pF to 20 \iF. Multimeter basics The preferred instrument for measuring resistance and volt- age is a digital multimeter, or DMM. All DMM's are based on a simple, single-range voltmeter. The nice thing is that converting a humble DMM into a measure- ment powerhouse requires only a handful of resistors and some switches. Intersil's 7106 is the basic building block of many meters. The 7106 contains an analog-to- digital converter (ADC) and it provides a three-digit output ca- pable of driving an LCD directly. A basic 7106 voltmeter that re- quires only three resistors and five capacitors is shown in Fig. 1. To calibrate the circuit, you must set the reference voltage at the wiper of R2 to 1.000 volt. That setting results in an overall range of 0.0 to 2.000 volts. Increasing range What if we want to measure a voltage greater than 2.000? To do so, we use a simple voltage divid- er, as shown in Fig. 2. With that simple addition, the incoming voltage is divided by the ratio of the two resistors to produce a voltage with a corresponding val- ue. In this case, the resistance ratio is 10:1, so the maximum voltage increases by a factor of ten, giving a total range of 0—20 volts. Measuring resistance The 7106 compares the incom- ing voltage to the reference volt- age between pins 35 and 36. By altering the circuit slightly, we can create an ohmmeter. as shown in Fig. 3. That circuit gives us another voltage divider. If the unknown resistance (R 1N ) equals Rrep the same voltage will appear across both the refer- ence and the measurement in- puts, resulting in a reading of 1.000. As the value of R m varies, the reading will vary accordingly. As for range, if the value of Rrep were IK, the range would be to 2K. For a range of 200K, R REF should have a value of 100K. Computer interfacing By now you're probably think- ing, "That's all well and good, but how do you hook up a 7106 to a PC? The output lines only drive an LCD!" Actually, what may at first seem like an odd approach is both simple and practical. Tb see why, let's look at a standard LCD readout. As shown in Fig. 4-a, the LCD consists of three seven-segment digits and a single leading "1," making a total of 22 segments. Figure 4-fo shows which seg- ments are used to display each integer from zero to nine; Fig. 4-c shows the same values, but with- out the use of segments c and d. The 4-cversions aren't pretty, but each one is unique, so a comput- er could read the 7106 segment outputs and translate the values into a more comprehensible form. By ignoring two segments from each digit, sixteen lines are required: five for each digit plus one for the leading digit. Reduc- ing the number of lines in that way is significant because it al- lows us to use a simple scheme to read each display segment into the computer and then deter- mine what the composite reading was. A pair of 4051 analog multi- plexers does the trick. The 4051 connects one of eight inputs to a single output according to the binary value at three control In- puts (A, B, and C). Using two 4051's with common control lines, we can monitor the status of sixteen inputs using only three output and two input lines from the computer. As shown in Table 1, when A, B, and C are all low, input is connected to the out- put; when A, B, and C are all high, input 7 is connected to the output. In our circuit, we connect the sixteen signal inputs of the two 4051s to the segment-drive out- puts of the 7106, and use the computer to control the A, B, and C control inputs. We also use the computer to monitor the pin-3 outputs of the 405 l's. The circuit The complete circuit is shown in Fig. 5. The circuit is slightly different from the basic circuit in that the reference and voltage in- puts are routed to a three-pole, double-throw switch (SI), which selects ohms or volts. In the "volts" position, the calibrate potentiometer (R10) is connected to the reference inputs of the 7106. In the "ohms" position, the reference inputs are connected to one of several reference resistors, as selected by analog-switch IC7. A 4030 exclusive-or gate (IC2) converts the segment-drive sig- nals to DC levels. The 7106 pro- vides segment drive and bp (backplane) signals, both of which are square waves. When a segment is to be illuminated, the phase of the segment output is shifted 180 degrees with respect to bp. By sending the bp and seg- ment signals through an exclusive-or gate, a steady low is obtained when a segment is off, and a high when it is on. That steady-state level can then be read by the PC through the pe and slct inputs. A normally-open pushbutton switch (S2) allows a diode or 48 EXPERIMENTING WITH PC- BASED TEST EQUIPMENT eDDOODDDQDOODCtCiCCOODODOOOOOOOODOOOdQOOOaDaOOD QQGOQOQ0QeOOGQ09Q0OQOOOOOOOCiDOQ3QQ PcIC I I/O Board! mm W d? 9 H ▼ Ifr j OOOD&OO 2000000000 i*4 ; oflcctf Of e> »a«ft*s9oaoc ooooe«DCM>oopoooo — iOOOOOC >OOOOOOOw lllfllli iMtr i f ri - i ni- rwTFiti ■ transistor junction to be for- ward-biased, thereby allowing measurement of the voltage drop across the junction. We incorpo- rated the capacitance meter (dis- cussed in the May 1991 issue of Radio-Electronics) in IC4 and IC6. In the schematic, note that there are two ground circuits. The reason is that the 7106 re- quires a supply greater than 6.5 volts, but the PC needs standard TTL levels. In addition, the meter inputs are referenced to the 7106s inlo input, which differs from the digital ground. We use a 9-voIt DC wall transformer to power the 7106 and associated ICs, and Zener diode Dl to gener- ate the required TTL levels for the PC interface. Construction We recommend PC-board con- struction for this project. Foil patterns are provided if you wish to make your own board. Begin construction by install- ing the 12 jumpers, as shown in Fig. 6. Next, install sockets for all seven ICs. Except for IC4, all ICs are static-sensitive — especially This time we build a low-cost PC-based voltage, resistance, and capacitance meter. JAMES J. BARBARELLO IC1 — so use standard precau- tions when handling those de- vices. Install the remaining components. There are 13 connections to PI , two connections for power, and 11 other connections. Prepare 24 lengths of wire, stripping Va" of insulation from both ends of each wire. Connect the desig- nated wires to PI and SI. If there is a plug on the lead from the power cube, remove it and strip Vs" of insulation from the two leads. Using a voltmeter, determine which is positive and which is negative, and attach each to the appropriate pad on the PC board. Don't mix them up! You can use whatever you like for input terminals. The author found it convenient to use a sol- derless breadboard strip with four rows of connection points. He ran leads from the ± resis- tance/voltage inputs to one pair of rows, and from the ± capaci- tor inputs to the other. That scheme allows quick insertion and removal of test components. A separate set of terminals pro- vides a quick connection for di- ode/transistor testing. Check your work carefully, making sure all semiconductors and the power leads were in- stalled correctly, and that there are no solder bridges or opens on the PC board. If you have an os- cilloscope handy, apply power and check for a square wave be- tween pins 38 and 40 of IC1; the frequency should be between 40 c m 49 V) o z O CL P u LLI o < + vj 1 3 4 5 •1 7 TO LCD<, -^ 12 4of 37_ CI 36 35 IC1 710B Rl + Vi R2 CALIBRATE TABLE 1—4051 DECODING 3-1 33 >C3 C3: — o + 0-2VDC INPUT 29 28 C5;*; 27 26 <;R3 25 \ 24 *1t. ^- > TO LCD 22 21 FIG. 1— A BASIC DMM can be built around Intersil's versatile 7106 and a few resistors and capacitors. 1C1 7106 3! 30 Rl 9.1MEG R2 909K -Oh 0-20VDC INPUT FIG. 2— INCREASE INPUT-VOLTAGE range by adding a voltage divider. In this circuit, range increases by a factor of ten. FIG. 3— MEASURE RESISTANCE with the 7106 as shown here. and 50 kHz. That measurement is not strictly necessary, but mak- ing it confirms that the circuit is operating. Software The software consists of sev- eral independent QuickBASIC programs for calibrating the de- vice and making different mea- surements. Unfortunately, there is not enough space to publish all of the programs. However, the software is available from the RE- BBS (file: PCTEST2.ZIP, 516-293-2283, 1200/2400, 8N1} A B c "0" T "2" "3" ■■4" "5" ,. g .. "7" X 1 X 1 X 1 1 X 1 X 1 1 X 1 1 X 1 1 1 X a f e b 9 d 1 =LdL 4 J= 6 =L==LJLJL " =J =" U "= !l = " W "=" ' ' II II ~~ I! II II II I II 1 I II « I . i =L 4 =L 6 7 8 9 I n ~n i_ii o_ n_ ii j = i ii^j ii i \C~ \\~ \~ ii FIG, A — THE 7106 DRIVES A 3 1 A- DIGIT LCD DISPLAY (a). Each integer from 0-9 is formed from a unique combination of segments (b): by ignoring segments c and d, each digit remains unique, but fewer lines allow a cleaner PC interface. PARTS LIST All resistors are '.t-watt. 5%, un- less otherwise noted. Rl, R4, R7— 100.000 ohms R2-^t70,000 ohms R3, R9— 10 megohms R5, R11, R12— 1000 ohms R6— 1 megohm R8— 10,000 ohms R1 0—100,000 ohms Capacitors C1— 100 pF, 5% C2, C3--0.1 u.F, 10% C4— 0,047 u.F, 10% C5— 0.47 u.F, 10% Semiconductors IC1— 7106CPL 3 1 /*-digit LCD A/D converter IC2— CD4030 quad xor gate IC3, IC5--CD4051 8-channei multiplexer IC4— 555 timer IC6, IC7— CD4066 quad bilateral switch D1— 1N4734 5.6-volt Zener diode Other components P1 — DB25 male connector S1 — 3-pole, double-throw slide switch S2— normally-open SPST pushbut- ton switch Miscellaneous: 9-volt DC, ! -b-amp wail transformer; case; solderless breadboard strip; PC board. Note: A compiled version of the software that also contains data- logging capability is available on 5%" double-density PC dis- kette for $12.00 from J J Barba- rello, RD#3, Box 241 H, Tennent Road, Manalapan. NJ 07726. The author will be happy to answer any questions. Please include a self-addressed stamped enve- lope for reply. 50 P1 TO PC PARALLEL PORT AUTOFD ACK«- 00 •- D1 »- D2*- D3»- D4»- D5»- D6»- D7»- PE« SLCT*- GND»- M ? 10 3 + 9V £ + 9V4 R3 omi:g +9Vn IC4 555 JO 14 T B4 100K IC6 4Q6C J^APAcrroRT^l^lU 4 ! 5 ! 6 ! input - 4, 8 7 5 13 7 6 S 12 7 IC7 4066 + 9V 14_J IT +9V R8 10K 8 -W* -VA- R7 1100K R11 1K 10 1MEG R9 10MEG 12 13 19 TO 9VDC WALL TRANSFORMER<- 01 j 1N4734 5.6V + 9V — O 12 IE 10 X1 xo X3 IC5 4DS1 A - c I/O K 15 P 10 "a INH A B G I/O IC3 4Q51 14 4 13 5 1^6 15 X6- XO XI 12 13 14 14 16 12 17 15 1B 4 19 Ltl A1 F1 G1 El B2 A2 F2 E2 IC1 7108 REFHI REFLO ?l 13 22 ?2 Z5 B3 F3 E3 AB4 tip G3 A3 HG2 NOTE; "#■ = DIGITAL GROUND fthj^ CIRCUIT GROUND + 9V DIODE R5 1K njft TEST DIODE INPUT R12 1K -*t+r-6 6-i OHMS MODE VOLTS 36 IN HI IN LO « m ci TOOK 10 opF 35 34 33 32 31 304 ~3_C2 JT\1 .C3 .1 79 ;;?. C5 ;k .47^ R2 470K ^Mh4 27 C4.„ .047" 26 mn *+9V R10 100K R/V INPUT CAUBRAifc FIG. 5 — COMPLETE SCHEMATIC. Data lines D0-D3 select one of eight segment- out put lines through the 4051 's (IC5, IC6). Range selection is accomplished by data lines D3-D6, which select one of four resistors through analog-switch IC7, The selected resistor, if any, is paralleled with R9, thereby decreasing effective resistance. FIG. 6 — MOUNT ALL COMPONENTS as shown here, installing the twelve jumpers first. and from the author, as men- tioned in the parts list. Listing 1 shows the resistance-measure- ment program. Calibration and use Both the hardware and the software must be calibrated. Be- gin hardware calibration by con- necting a DMM across the wiper and the lower end of RIO, and set SI to the "volts" position. Apply power and adjust RIO until the DMM reads 1.000 volt. Begin software calibration by executing the OHMFAX program. The screen will initially show null calibration factors for the five re- sistance ranges, R1-R5. The pro- gram asks whether you want to revise those values; press Y and enter the following initial values: Rl. 10000; R2, lOOO; R3. 100; R4. 10; R5, 1, The Revise question will appear again; press N this time. Then the program asks whether to save the values you just entered; press Y. Now the LISTING 1 to o z o readingold THEN readingold REH REM**** STEAD* STATE READING - DISPLAY REM LOCATE 9, 5 IF imsk - 1 THEN PRINT USING " M.M Mohms" ; reading 1000000: measuredvalue - reading * r(imsk) / 1000000 10 + ones reading: GOTO begin reading * IF imsk - 2 THEN PRINT USING " J»M Kohms 1000: measuredvaluo - reading * r(imsk) / 1O0O IF imsk - 3 THEN PRIHT USING "#M.* Kohgna "; reading 1000: measure dv a it: a - reading * r(ibsk) / 1000 IF imsk - 4 THEN PRIHT USING " It.t Kohms 1D0O: maaeuredvalue *• reading * r(iask) / IF imsk - 5 THEN PRINT USING » Li , 2H*+2e Oxygen, air, or hydrogen perox- ide (a source of oxygen) is fed to the cathode, where it is reduced, whereby the O a oxygen molecule splits apart. Ionic conduction completes the circuit through the electrolyte. Hydrogen and oxygen react to form water, as this chemical equation shows: 2 H 2 + O a -*2H a O, or Hydrogen + Oxygen -• water If hydrazine is oxidized, addi- tional nitrogen is formed which is a normal constituent of air, and also safe: c m s 61 g z s UJ _i hi Q D < It N^+Oz^HsO + Na, or Hydrazine + Oxygen— Water + Nitrogen You may be tempted to say that if hydrogen is such a "clean" fuel, we can just burn hydrogen in air and get pure water as the com- bustion product plus power. Burning hydrogen would indeed be a considerable improvement over burning coal, oil, or gas- oline. However, when air is burned, a large amount of nitro- gen is drawn into the combus- tion chamber and heated to roughly 1000°C. At that tempera- ture, it partially reacts with oxy- gen and forms oxides of nitrogen. So, even though the reaction product of the main reaction is pure drinking water, the side re- action spoils it all by making the resulting water unsuitable to drink. If hydrogen and oxygen re- act in a fuel cell at room tempera- ture, that problem is eliminated. Space-age power The desirable characteristics of fuel cells led to the develop- ment of various systems ranging in size from 5-watt portable units, to the kilowatt (kW^ power level for military applications, on up to large stationary plants de- livering megawatts of power. The lower-power fuel cells were de- signed primarily for the space program and front-line military use where ease of operation, low maintenance, and low noise are important. Fuel cells are used solely for power generation of space crafts because of one chief advantage: when power is required for more than a few hours, the battery weight per kilowatt-hour as a function of its operational life is far superior to that of conven- tional battery cells. A relatively light-weight fuel ceD can have a lifespan of five to ten times that of a primary battery. FUel cells built between 1960 and 1970 for the Gemini and Ap- ollo space missions and in 1980 for the Space Shuttle Orb iter are among the most successful fuel cells to date. They were needed because of their chief advantages over batteries- — weight and life- span. Those fuel cells used cryogenic reactants of hydrogen and oxygen. Some space-craft power gener- ation systems use solid polymer FIG. 1— THE AUTHOR'S FUEL CELL uses two adjoining chambers separated by a semi- permeable membrane. The chambers are filled with an electrolyte. Hydrogen is directed to one electrode, oxygen to the other. FIG. 2 — IONS TRAVEL ALONG a gel-on bridge in a glass tube placed in the electrolyte solution. FIG. 3— THE CONTAINER used for the fuel cell consists of square-based 250-ml poly- ethylene bottles with holes cut in their sides. A round piece of fine glass was cemented in with sealing wax and an additional layer of beeswax. electrolyte (SPE) technology in the construction of their fuel cells. That type of fuel-cell assem- bly consists of an ion-exchange membrane-electrode system with gas distribution, current collec- tion, heat removal, and water management. Many of those as- semblies are bolted together be- tween end plates to form an SPE stack assembly The Gemini system used three 1-kW SPE fuel-cell stacks. The Apollo system used a larger 1.5- kW fuel-cell stack based on a con- centrated 45% potassium-hydro- xide electrolyte. The Apollo power plant was designed to operate for over 400 hours. The fuel cell in Apollo 8 lasted for 440 hours, the system produced 292 kWh of power, and 100 liters of water. 62 The Space Shuttle system was more advanced in design than ei- ther the Gemini or Apollo fuel cells. The Space Shuttle fuel cells are 20 kilograms lighter and de- liver six to eight times as much power. Each fuel cell power plant consists of a power section where the chemical reaction occurs, and a compact accessory section connected to the power section, which controls and monitors the power sections performance. The three fuel-cell power plants are coupled to the hydrogen and oxygen reactant subsystem and the power distribution sub- system. The fuel cells generate heat and water as by-products of electrical power generation. The excess heat is directed to Freon coolant loops, and the water to a potable water storage subsystem. Some power specifications of each fuel -cell power plant are: • 2 kilowatts at 32.5 VDC. • 12 kilowatts at 27.5 VDC. • 7 kilowatts continuous power. • 12 kilowatts peak. • All three fuel cell power plants are capable of supplying a max- imum continuous output of 21,000 watts with 15 minute peaks of 36,000 watts. Some experimental fuel cells have been considered for use with vehicles. The major pro- hibiting factor in their use is the difficulty in reliably containing hydrogen gas, and the possibility of an explosion. Also, special fuels such as hydrogen, meth- anol, and hydrazine are more ex- pensive than hydrocarbon fuels. Many advanced fuel-cell de- signs have been developed for power utility applications, but because of the typical problems of fuel storage and cost effec- tiveness, they have not been widely used. An experimental fuel cell The author was able to build a successful experimental fuel cell by the technique described be- low. We must, however, issue this word of caution: This product should NOT be built or experi- mented with in any way except under the direct supervision of someone who is highly qualified in the fields of chemistry or chemical engineering. Some chemicals and gaseous by-prod- ucts in a fuel cell could be toxic and/or explosive! All dangerous CHEMICALS USED IN FUEL CELLS • Hydrogen — A colorless and odorless gas which is sold com- pressed in steel bottles. Small lab- size bottles are available together with simple low-priced reducing valves. Hydrogen is not poi- sonous, but extremely flammable and forms explosive mixtures with air, • Oxygen— Also is sold in com- pressed form in lab-sized bottles. it is not toxic but must be kept from fire or flame since it will sup- port combustion and can make a four alarm fire out of a glowing match. • Hydrazine — Anyone not used to working with dangerous chemi- cals should not handle this com- pound, it is carcinogenic and should be dispensed in a hood only. Hydrazine should be handled with rubber gloves. • Hydrogen peroxide 30% — Most everyone knows this chemical as a 3% solution for bleaching or wound treatment. The 30% con- centration will bleach the skin and is dangerous when swallowed. Handle with rubber gloves. • Sulfuric acid— It is poisonous when swallowed. It can blind you if splashed in the eye. It will bum holes in your clothes. A solution in water should be prepared by slow- ly pouring small amounts into plenty of cold water while stirring with a glass rod. Handle with rub- ber gloves. • Potassium hydroxide solution 30% — Potassium hydroxide is a strong base and is poisonous. 300 grams are dissolved in 900 milli- liters of cold water. Let It stand and cool off. Store in a plastic bottle with cap. Handle with gloves, it can damage the skin. • Palladium dichloride — Dark brown crystals soluble in water. Moderately poisonous when swal- lowed. Dissolve 2 grams in 100 mil- liliters of water. chemicals are listed in the side- bar. You must be familiar with proper handling and disposal of any chemicals used. The author's experimental fuel cell uses two adjoining chambers separated by a membrane, as shown in Fig. 1. An electrode with catalytic properties is placed into each chamber. Both cham- bers are filled with a liquid elec- trolyte. One electrode is then purged with hydrogen gas, the other with oxygen or air, and a voltmeter is connected across the electrodes. In order to be able to build a fuel cell you should be familiar with semipermeable membranes and catalysts. Semipermeable means that only some ions can pass through it but other matter is retained. In actual applica- tions, separation of ions is not perfect, and some leakage usu- ally occurs, and is permissible. Total blockage on the other hand would inhibit a reaction. The fol- lowing materials could be used as semipermeable membranes: • Unglazed discs of baked clay (an old clay flower pot). • Fine glass frits (the partly fused mixture of sand and fluxes which glass is made of). • Cellophane. • Wet plaster. • Moist, or hardened cement. • Zinc oxide or zinc chloride cement. • Certain types of plastic foam. • Silicic acid gel, prepared by slowly acidifying sodium silicate solution. • Gelatin saturated with salt. Clay, cement or plaster discs should be as thin as possible. The gels should be used to build ion bridges according to Fig. 2. Glass frits can be bought at lab supply houses and are best for this use. If glass frits are used, the gases move upward, and stay in the proper place. Any fair sepa- ration will do. The author used two square polyethylene bottles and a large fine glass frit which was glued into holes cut in the sides of the bottles (Fig. 3). In order to get hydrogen and oxygen to react at room tempera- ture they must be coaxed a little. Without the proper catalyst, nothing at all happens. A catalyst is a compound that hastens reactions without actu- ally taking part in the reaction. If you set up a H 2 /O a fuel cell with sulfuric acid and carbon elec- trodes for instance, there will be no electrical energy generated. If platinum- or palladium-coated carbon electrodes are used, the reaction gets going. Union Car- bide has used this method and supply such electrodes. The method the author used to plate carbon was to wrap plati- num wire and a platinum net around the carbon rods, which works very well. An easy and low- priced way of producing a large £ surface of palladium is to coat ^ nickel netting with palladium. - That can be done by immersing a 2 6 nickel net in a 2% solution of pal- drogen to disperse. Rotameters nents that react at room tempera- ladium dichloride over night. were used to check gas flow. They ture are shown in Table 1. The The coating looks black. Pal- can be replaced by bubble indica- fuel cell can also be used as a one- ladium coated nickel acts like tors if you prefer. Gas flow was shot unit for liquid fuel, namely pure palladium. The author had 10-20 liters per hour (l/h) but can hydrazine, and 30% hydrogen a supply of platinum on hand or be varied. Oxygen flow should be peroxide. Both compounds are he would have used the approach about % that of hydrogen flow. rocket fuels but can be controller: just mentioned. The reaction is sluggish at the very well. They are, however. The amount of palladium di- beginning as hydrogen has to highly toxic and poisonous. Be- chlorides you need costs about saturate the platinum metal sur- cause hydrazine is known to be a S20.00, Platinum, palladium, sil- face. carcinogen, one should not work ver, nickel (especially Raney nick- An indication of about 10 mV with it unless you are familiar el) have been used as catalysts in may occur for several minutes, with handling very poisonous different fuel cells. Platinum- which will then rise. There may substances. Hydrogen peroxide group metals work so well be- be steps in this rise, therefore it at 30% concentration will bleach cause they have an affinity to hy- may be necessary to put a little your hands and should also be drogen and will pick up consid- drain on the system by using a handled very carefully. TABLE 1 FUEL-CELL COMPONENTS THAT REACT AT ROOM TEMPERATURE Fuel Oxidant Electrode Material Electrolyte Catalyst Recorded Voltage (mV) hydrogen 20 l/h oxygen 10 l/h carbon 5% sulfuric acid none No reaction hydrogen 20 l/h oxygen 10 l/h carbon/platinum 5% sulfuric acid platinum 533 hydrogen 20 l/h air 40 l/h carbon/platinum 5% sulfuric acid platinum 469 hydrogen 20 l/h oxygen 1 l/h platinum 30% potassium hydroxide platinum 988 hydrogen 20 l/h oxygen 10 l/h palladium on nickel 30% potassium hydroxide palladium * 2 ml 24% hydrazine hydrate 10 drops 30% hydrogen peroxide palladium on nickel 30% potassium hydroxide palladium * This reaction was not tried by the author, but works according to literature on the subject. ■I) u z o LU o Q < DC erable amounts of it for storage in their crystal lattices. A plati- num electrode saturated with hy- drogen, therefore, is practically an electrode of solidified hydro- gen. The pure metal is too expen- sive, so palladinized nickel, platinized carbon or Raney nick- el on a carrier matrix are the first choice. Impinger-type glass tubes wi th frits or aquarium-type disper- sion tubes are used as gas inlet tubes. The electrodes are wound around the tube in a coil. Copper wire leads are connected. The electrolyte is a 30% potassium hydroxide solution. Oxygen and hydrogen can be bought in small laboratory bottles with reason- ably priced lab-reduction valves. Hydrogen can also be produced from zinc and diluted hydro- chloric acid. That leaves you with a solution of zinc chloride which is hazardous to the environment and must be disposed of in a manner prescribed by law. The entire experiment was conducted in the open air in order to allow the flammable hy- 100-ohm resistor connected across the 2 chambers. It can be removed again after a few min- utes. That helps overcome polar- ization effects. The author mea- sured 998 mV after about 10 minutes. To compensate for the slow start, the cell will generate a voltage for some time after the hydrogen is turned off. After you finish, the potassium hydroxide solution should be poured into a well-capped plastic bottle. It can be used over again, but it will accumulate carbonate which makes it less effective. Some prefer diluted sulfuric acid for the same purpose because it keeps longer. Air can, in most cases, be substituted for oxygen. The amount must be raised, however, since only l /s of air is oxygen. Hydrogen peroxide can be used in place of oxygen but it dilutes the electrolyte. Hydrogen can be replaced with hydrogen-containing gases such as "city gas" produced from coal, containing hydrogen, methane, and carbon monoxide. Several variations of fuel cell compo- Fuel cells have been run with "steam reformed" methyl alcohol. At 200°C, methyl alcohol reacts with water to form hydrogen and carbon dioxide as shown in the following equation: CH 3 OH + H z O-3H 2 + C0 2l or methyl alcohol + water-* hydrogen + carbon dioxide At temperatures higher than room temperature many other re- actions are possible. Some of them allow a separation and col- lection of the water formed. You're probably wondering why fuel cells are not more widely used. The first big drawback is cost, which is always a primary consideration in power genera- tion. Hydrogen is an expensive fuel compared to other types of fuels, and the storage of hydro- gen is still a problem. Perhaps in the future, we'll use solar energy on a large scale to decompose water into hydrogen and oxygen, which can then be stored. When energy is needed, the two gases can be recombined to water in a fuel cell. R-E 64 Let's look at electronic tuning diodes, some unusual newsletters, parametric amplification, association book resources, and preventing modem dropouts. DON LANCASTER We might start off with the reminder that we do have our technical helpline avail- able for your use per the box below. That's where you can go for tech help, referral to highly qualified consul- tants, for book and software pur- chases, and for general ofF-the-wall networking. Your best calling times are week- days 8-5. Mountain Standard time. Before you call, please re-read the entire column and especially the Names and Numbers and Resource boxes. Hardware Hackers calling without a pencil or pen handy will get chopped up and fed to the cows. You could also reach me via my personal BBS, otherwise known as GEnie PSRT. Call (800) 638-9636 for voice connect info. But, please do note that I am an independent developer and author sitting here on my sand dune in the middle of the Upper Sonoran desert, I have very little input to any Radio- Electronics editorial policy and know next to nothing about projects by other authors. To leave comments for the editors, you may want to use the RE-BBS at (516) 293-2283. Yeah, I sometimes do welcome any visitors that call in advance. But do note that Gurus are supposed to be hard to reach, because (A) it adds to the mystique, and (B) the Guru's and Swami's Union Local #415 rules de- mand it. At any rate, there is a seven- hour drive involved in reaching the nearest airport from here, I won't even mention the deadly Gifa Mon- sters or hostile Indians. Every once in a while I'll get a call that sounds reasonable at the time, but after thinking things over... For instance, one Hardware Hacker wanted to crystal control that low- cost BA1404 FM stereo broadcaster weve looked at in past issues. He wanted to do this so that several ac- tors in a play could be on the same frequency. Uh, whoops. You can't get there from here. Sure, you can crystal con- trol your BA1404. And you certainly can put as many of them as you want on the same frequency. But one of the key properties of FM reception is that you will receive only your strongest station, with virtually zero pickup of any of those others. That normally desirable action is known as the FM capture effect and is caused by the hard limiting present in virtually all FM receivers. As little as a fraction of a decibel can cause any one signal to utterly and totally dominate. Sorry about that. We return you to our col- umn already in progress... Electronic tuning The traditional method of tuning a resonant circuit to your desired fre- quency is to use some adjustable or variable capacitor. While obvious and cheap, those capacitors are often large and sometimes expensive, could be sensitive to fields and vibra- tion, and usually require human inter- vention for their use. These days, it is much better to go to one or more eiectnonic tuning methods. The simplest method of electronic tuning is to never do it. As much as possible, you purposely design out any need for a variable capacitor or a direct replacement. For instance, you use digitally synthesized frequencies instead of a local oscillator or BFO. You use switched-capacitor filters or active filters that are tunable by an input frequency or voltage. Or you use ceramic or SAW filters that are so precise and so repeatable that no NEED HELP? Phone or write your Hardware Hacker questions directly to; Don Lancaster Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 adjustment is needed. You also tend to use a few higher-quality filters, rather than lots of individually tuned and cascaded LC circuits. But after all of that, there remain times and places where you'll still need a few electronically variable ca- pacitors. Selecting a station on a ra- dio or TV are obvious examples. One very popular, well performing, and ultra-low-cost electronic tuning method is called a varactor diode, sometimes known by the trade- marked name Varicap. Varactor di- odes are diodes that have been optimized to look and behave like a high-quality electrically variable ca- pacitor. Most any diode conducts current in the forward direction and blocks it in the reverse direction. Specifically, when you reverse bias a diode, you create a depletion region containing neither electrons nor holes. As you increase your reverse bias, the deple- tion region gets thicker, and vice ver- sa. Thus, any diode will behave as an electrically variable capacitance as you vary its reverse bias voltage. For most diodes, this unavoidable depletion region capacitance is a flaw that restricts your maximum speed of operation. But in a varactor diode, the depletion-region capacitance is pur- posely made rather large, quite high quality, and very controllable. Figure 1 shows you a typical circuit. From the electrical control side, you simply reverse bias your diode by way of a large series resistance or some other method that has a very high RF impedance. When you change the value of the voltage, you electrically change the capacitance of the varac- tor's depletion region, and thus tune your circuit. Typically, you change your tuning voltage over a 3- to 30- volt reverse-bias range. On the resonant circuit side, you do have to provide a DC return path £= to ground for the tuning voltage bias, z You also have to provide a series ^ blocking capacitor to keep any other 2 65 DC path from shorting out your di- ode. Normally the series capacitor is very much larger than the varactor's capacitance, so it does not signifi- cantly alter any of your resonance cal- culations. Sadly, the varactor's capacitance changes nonlinearly with the reverse voltage. Depending on the varactor, you might have 60 pF at 1 volt reverse bias, 45 pF at 2 volts, and 18pFat20 volts. Thus, your first couple of votts of reverse bias will by far give you the most variation. The plot of capaci- tance versus reverse voltage is roughly linear when plotted on semi- log paper. Varactor capacitances can go from a fraction of a picofarad with exotic microwave devices on up to several hundred or more picofarads for use in audio filters or AM tuning. You can sometimes use giant silicon power diodes for lower frequency varactor experiments. But the wi H often be low when you try that, and the tuning range will be limited. The capacitance range of a varac- tor is usually defined as the ratio be- tween your 3- and 30-volt bias settings. An ordinary varactor will often have a capacitance range of g z o \3 O Q < EC NEW FROM DON LANCASTER HARDWARE HACKER STUFF Hardware Hacker Reprints II or III 24.50 Midnight Engineering Reprints 16.50 Incredible Secret Money Machine 12.50 CMOS Cookbook 24.50 TTL Cookbook 19.50 Active Filter Cookbook 19.50 Micro Cookbook vol I or II 19.50 Lancaster Classics Library 109.50 Enhancing your Apple I or II 17.50 Apple Writer Cookbook 19.50 Absolute Reset He & lie 19.50 Enhance I or II Companion Disk 19.50 AppleWrlter CB or Assy CB Disk 24.50 POSTSCRIPT STUFF Ask The Guru Reprints I, 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 (Adobe) 22.50 PostScript Program Design (Adobe) 22.50 Type I Font Format (Adobe) 15.50 La serWr Iter Ref ere nee { App le) 19.50 Real World Postscript (Roth) 22.50 PostScript Visual Approach (Smith) 22.50 Thinking in PostScript (Reid) 22.50 The Whole Works {all PostScript) 299.50 FREE VOICE HELPLINE VISA/MC SYNERGETICS Box 809-RE Thatcher, AZ 85552 (602) 428-4073 WW- t3 to +30 VDC TUNING VOLTAGE VARACTOR DIODE FIG. 1— ELECTRONIC TUNING using a varactor diode. The diode depletion -layer capacitance varies with the applied re- verse bias. The large series capacitor serves as a DC block to prevent shorting out the tuning voltage. 3:1. But note that a frequency change varies with the square root of your capacitance change in any resonant circuit. So. this type of 3:1 varactor can shift a resonant frequency only by 1.73 or so. One way to increase the range of a Varactor is to cheat and use a lower bias voltage. Your capacitance will in- crease dramatically for very low val- ues of reverse bias. But at that point the diode will start to conduct and very much reduce the available or selectivity for your tuned circuit. Lin- earity will also be awful. For wider tuning ranges, special varactors are obtainable which have different doping profiles. Varactors with a medium tuning range have an abrupt doping profile, while those with very high tuning ranges use a hyperabrupt profile. The tradeoffs for a wider tuning range are more noniinearity, some- what higher cost, lower circuit Q, and harder tuning. It will also become vastly more sensitive to noise and the precision of your tuning voltage. The AM broadcast frequencies of 550 to 1650 kilohertz have a 3:1 range. Thus, you should use a hyper- abrupt varactor having at least a 9:1 and preferably a 10:1 tuning range here. The hyperabrupt Motorola MVAM108 is one good choice here, having an extreme 15:1 range. Those television frequencies are spread out over a very wide range. To prevent having to tune them all at once, three varactor tuners are sepa- rately used in several individually se- lected circuits. One for the lower VHF channels 2-6, a second for the high VHF channels 7-13, and a third for the remaining UHF channels. And sometimes a fourth for special cable channels. Note that there is a rather large frequency gap between channel 6 and channel 7 that holds both the FM broadcast band and emergency services. Should you instead want to restrict the tuning range of a varactor, you can either put a fixed capacitor in parallel with it or else use a narrower voltage control range. The fixed paral- lel capacitor is often the better choice. Varactors work best with tuned signals in the microvolt range. Should your signals being tuned get above several millivolts, the signals them- selves can add to or subtract from the tuning voltage. Thus, your positive signal excursions will increase the resonant frequency and vice versa — which can introduce moderate to se- vere second- harmonic distortion. You might resolve that possible distortion problem by using a pair of varactor diodes as shown in Fig. 2. The two varactors are in parallel as far as the DC tuning voltage goes, but are in series with any signals being tuned. Thus, on a positive peak, the capacitance of one Varicap will in- crease as the other decreases, and largely cancel each other out. Dual varactors in a single package are rather popular. The Motorola MVW4 is one example. Note that two capacitors in series give you one half the total capacitance. Be sure to allow for that in your designs. It is extremely important to have a very stable reference for your tuning voltage, since any drift at all could detune your circuit. If possible, you will also want to use some sort of feedback to keep your tuning locked on channel. Various types of auto- matic frequency control (AFC) can sometimes do that for you. Sadly, varactors drift over temper- ature. Their values will increase with increasing temperature. One typical value is in the 200-parts-per-million range. On the other hand, a regular diode that is forward biased will have 1 VARACTOR DIODF #2 | — w*\ < +3 10 +30 VDC TUNING VOLTAGE I VARACTOR DIODE #1 FIG. 2— A PAIR OF BACK-TO-BACK varac- tor diodes can be used to prevent larger signals from detuning themselves. A positive signal swing raises the capacity of one varactor and lowers that of the other. The changes largely cancel out. Ftl ■ cost 680093 500 ! 4. !s 680097 B40 ! 5. 95 680098 2 1380 s 11. 75 680(00 4 2390 s 22. ss WIRE JUMPER KIT Pre-cut. Pre-S, ripped 140 Piece Set „...' 4. 7S 350 Piece Set s 7. 75 COMPONENTS StOCk Mo. 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Almost everyone agrees that dis- tortion is not a good thing. But beyond that basic point, arguments start. Exactly what's the problem? Simply this: Electronic audio distor- tion, while easy to measure in its vari- ous manifestations, is devilishly difficult to correlate with the percep- tions of the human ear/brain appara- tus. The situation is further compli- cated by some manufacturers of expensive audio equipment, ac- cessories, and connecting wires, who are pleased to invent wonder- fully esoteric distortion problems (with accompanying voodoo solu- tions) to satisfy the needs of the de- vout tweaks and techno-crazies. Terminological confusion My Illustrated Encyclopedia of Electronics tells me that "Distortion is any change in a signal that alters its basic waveform or the relationship between its various frequency com- ponents." Some of the misunder- standing about standard distortions and their audibility arises from ambi- guities in terminology For example, sometimes the technical name for a distortion describes the way the af- flicted waveform looks on a scope (e.g., clipping distortion when the tops and/or bottoms of a waveform are decapitated); other times the name refers to the electronic flaw in the amplifier that produces the prob- lem (e.g., crossover distortion). The terms harmonic distortion (HD) and intermodulation distortion (IMD) in effect describe kinds of test procedures rather than specific flaws in the equipment under test. If an am- plifier has a problem, the same con- g dition should show up on both HD z and IMD distortion tests— and pro- § vide entirely different measurement £5 numbers. Keep in mind that the num- [j bers provided by distortion-testing in- ji> struments are somewhat arbitrary; 5 they depend as much on the type of cc test and the specifics of the test sig- nal used as on the magnitude of the flaw in the amplifier. And for perhaps the same reason, none of the distor- tion-measurement numbers correlate directly with audible unpleasant- ness—or with each other. In other words, 2% distortion does not nec- essarily sound twice as bad as 1 %, or even necessarily worse than 0.5%. Harmonic distortion In any discussion of harmonic dis- tortion, keep in mind the distinction between the natural harmonics that are a part of all tones produced by musical instruments and the un- desired spurious harmonics that re- sult from flawed amplification. It is the natural harmonic content that causes the same musical note played on a clarinet, a piano, and a flute to sound different — and to look different on an oscilloscope. Any complex waveform can be "discussed" by a mathemati- cal process known as a Fourier analy- sis and shown to be composed of a large number of odd and even har- monics. Figure 1 shows a violin note and its second, third, fourth, fifth, six- th, and eighth harmonic components. With the proper instrumentation, it is possible to detect harmonics as high as the twentieth. HD comes about nor through dis- tortion of the harmonics of a signal, FIG. 1— FOURIER ANALYSIS of a violin note showing the relative strengths of the strongest natural harmonics. nor does it result from spurious har- monic frequencies generated by an oscillating amplifier. What happens is that the amplifier, because of some technical inadequacy, changes (dis- torts) the original shape of the signal waveform. That change can be quan- tified by analyzing it in terms of the spurious harmonics added to the fun- damental test signal — which is, in general, the way the ear hears it. When testing an amplifier's HD performance, you feed in as distor- tionless a sine wave as can be gener- ated. The HD analyzer, which is connected across the amplifier's out- put test load, operates by nulling out the input test signal and reading (as a percentage of it) whatever harmonics and noise are introduced by the am- plifier, if, say, a 3-kHz test signal was used, amplifier nonlinearity might produce spurious harmonics at 6 kHz, 9 kHz, and so forth. The term THD indicates that the lumped total of all the harmonic components is included in the measurement. A more sophisticated instrument, called a spectrum analyzer, is capable of indi- cating the relative strengths of each of the spurious harmonics. It is rec- ommended by the EIA Amplifier stan- dard (RS-490) and is used by many test labs. To illustrate the mechanisms in- volved, an exaggerated example of distortion is shown in Fig. 2, Let us say that a malfunction of the amplifier causes third-harmonic distortion of waveform (a), a 1000-Hz sine-wave input signal. The distorted output sig- nal (c) would look as though a 3000- Hz tone (fa) were combined with the 1000-Hz tone. Keep in mind that a distorting amplifier does not actually generate spurious harmonic wave- forms and mix them with the original wave; what it does is distort the origi- nal waveform in such a way that the output waveform looks as it would if specific spurious harmonics were added. Of course, in real life we would have not only third-harmonic distortion but also an assortment of various odd and even harmonics of various strengths. 72 FIG. 2— SIMPLIFIED ILLUSTRATIONS of how a spurious third harmonic (b) combined with the Input signal (a) produces a distorted signal (c). There's some evidence that the specific HD content of a distorted signal (meaning the relative strengths of the distortion components extend- ing up to the tenth harmonic or high- er) is more audibly significant than the absolute THD figure. In other words, depending upon the ways that two amplifiers are distorting a piece of music, a measured 3% THD from one might sound a lot worse than 3% from the other. Intermodulation distortion The same amplifier nonlinearities that produce THD also produce inter- modulation distortion CIMD), but through a somewhat different mecha- nism. When two (or more) signals are fed through a nonlinear amplifier, the signals tend to intermodulate, mean- ing that they interact in a specific and undesirable way. ff, for example, a low-frequency signal of 40 Hz was traveling through a nonlinear amplifier along with a higher frequency of, say, 2 kHz, spurious sum and difference frequencies that are known as IM products would be produced at 1920, 1960, 2040. 2080 Hz, and so on and so forth. There are two different IMD test techniques in current use, both em- ploying a pair of test tones applied simultaneously. The older SMPTE (Society of Motion Picture and Televi- sion Engineers) IMD test uses a com- posite 60- and 7000-Hz test signal in a 4:1 ratio, while the tHF-IM test uses two equal-amplitude high-frequency tones. The description of the IHF test incorporated in the current EIA Stan- dard (formerly IHF-A-201 1966) reads as follows: "The percentage of IHF intermodulation distortion (IHF-IM) of a composite signal composed pri- marily of two relatively high-frequen- cy sinusoidal signals, one having a frequency of r", and the other having a frequency of f 2 , of equal amplitude, is numerically equal to 100 times the square root of the sum of the squares of the second- through fifth-order dis- tortion components divided by the square root of the sums of the squares of the amplitudes of the sums of the components at frequen- cies f, and f 2 ." All of which, I think, helps explain the relative popularity of the SMPTE method over the IHF-IM method. Unlike THD, IMD distortion com- ponents do not have a harmonic reia- tionship with the music and, therefore, can't be heard as part of the music. For that reason, IMD is generally thought of as more audibly unpleasant. However. I would say that, given the very low distortion fig- ures of ail of today's better standard- brand audio amplifiers, neither THD nor IMD are likely to be audible, assuming that the amplifier is working properly and is never driven into over- load. And, even under overload clip- ping conditions, with complex pro- gram material such as a loud symphonic work, it is well docu- mented that distortion (of any flavor) has to reach approximately 6% be- fore it becomes audible. That is true because the spurious distortion fre- quencies are overwhelmed (tech- nically, "psychoacoustically mask- ed ") by music occurring at the same frequencies. However, when the test signal is a pure tone, distortion as low as 0.15% can be heard. Probably for all of the above reasons, it seems that few professional testers will bother with IM measurements. In next month's wrap up on our distortion discussion, we will look at some of the popular "new" distor- tions and try to place the entire topic in a real-world context. B-E &?&)&& m ^tSSafi ma «f: • «?®»3;.i*5Hfe- B 5 >* ">& 5*. «% *&-' CIRCLE 108 ON FREE INFORMATION CARD Be an FCC ■WsUWdl ELECTRONIC TECHNICIAN! fal Earn up to $30 an hour and more! T 5 Learn at home in spare time. 1 No previous experience needed! No costly school. No commuting to class. The Original Home-Study course prepares you for the "FCC Commercial Radio- telephone Licen se," Thi s va luable li cense i s your professional "ticket" to thousands of exciting jobs in Communications. Radio- TV, Microwave. Maritime, Radar, Avionics and more. . .even start your own businessl You don't need a college degree to qualify, but you do need an FCC License. No Need to Quit Your Job or Go To School This proven course is easy, fast and low cost! GUARANTEED PASS— You get your FCC License or money refunded. Send for FREE facts now. 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Plus you learn to use your QuickTech diagnostic software to test the system RAM and such SEND TODAY FOR FREE CATALOG McGraw-Hill Continuing Education Center 4401 Connecticut Avenue, NW SChOOlS Washington, DC 20008 [»fCHECK ONE FREE CATALOG ONLY H Microcomputer Servicing □ Computer Programming C Automotive Servicing □ Locksmith] ng P PC Systems Analysis D Paraglegal U Industrial Electronics & Robotics L Electrician i: I □ PC Software Engineering Using C □ Telecommunications G Small Engine Repair G Word Processing Home Business □ Electronic Music Technology Q Fiction/Nonfiction Writing For career courses approved under GI Bill, check for details. □ Building Construction □ Desktop Publishing & Design □ Security Electronics D TV/Video/Atidio Servicing B Bookkeeping & Accounting O Basic Electronics □ □ Air Conditioning, Heating, & Refrigeration Name I (please print) Age Address I City/State/Zip Accredited Member, National Home Study Council 3 061 ZH!iEiEniEE5ME Windows watch JEFF HDLTZMAN CO o 2 O CC F o UJ _J LLJ 6 Q < DC Windows is really taking the PC world by storm. By the time you read this, it will have been a year since Windows 3.0 was released. What's happened in the interim? Where are things going? Virtually all interesting software de- velopment is now focused on the Windows environment. The major computer magazines have spon- sored speciai sections on Windows products, and the technical columns formerly associated with OS/2 now grudgingly include Windows informa- tion as well. Hardly a day passes when a new, upgraded, or converted product does not appear for the Windows environ- ment. In some cases, these new products are spectacular; in pthers, disastrous. The latter remind me of the early 80s, when the industry made the transition from CP/M to MS-DOS. The first applications were straight ports that worked worse un- der DOS than they did under CP/M. But gradually, the old applications im- proved, and new ones were intro- duced. In some cases, the old apps (e.g., WordStar, dBASE) remained mired in the bog of the past and. though they're still hanging on, have yet to capitalize on the unique strengths of the new environment. Of course new apps (e.g., 1-2-3) learned to stretch that environment to the lim- it — and beyond. For example, Lotus was a driving force behind Hercules graphics adapters and the EMS specification. Now the industry is going through another tectonic shift. Highly influen- tial companies [Borland, Lotus. Word Perfect, Software Publishing) that heretofore have ignored Windows are now scrambling to get something to market as soon as possible. And some companies (WordStar, Lotus again) are trying to buy their way in. Meanwhile, with control of the oper- ating system (DOS) and the operat- ing environment (Windows), serious applications (Word, Excel, Power- Point, Project) in all major categories except database and telecom- munications, and a LAN operating system (LAN Manager) worthy of being taken seriously, Microsoft's dominance of the industry continues to increase. Windows and OS/2 Why has Windows usurped the po- sition many people once expected OS/2 to occupy? There's no good reason on technical grounds. Win- dows requires just as much in the way of system resources (CPU, RAM, hard disk) as OS/2. And with that same set of resources , Windows pro- vides a less-stable, less-powerful en- vironment for running programs than OS/2. There's lots of grumbling in the de- veloper community about Microsoft's seeming desertion of OS/2. People working in that environment have in- vested lots of time and effort learning the OS/2 API (Application Program- ming Interface). And now they're find- ing that the expected market for their products seems to have disap- peared. Further, due to the large dif- ferences in API's, converting their OS/2 work to Windows is difficult. For a while last fall, Microsoft was touting a so-called binary-com- patibility layer (BCD that would allow Windows programs to run un- modified under OS/2 2.0, the still- unreleased 386-specific version of the operating system. In practical terms, that amounts to adding a layer of software to translate Windows calls to OS/2 format. However, there were lots of questions about whether that type of kludge was even possi- ble. In addition, given the lackluster performance of both environments on anything less than a 25-MHz 386, it's hard to believe that users would accept that type of performance-de- grading solution. Recently emphasis has shifted to OS/2 3.0. a "portable" operating system that will run on multiple hard- ware platforms, and will allow mixing and matching multiple API's (DOS, Windows, OS/2, POSIX), file sys- tems (DOS. HPFS, POSIX), and graphical user interfaces (Windows, OS/2 PM. X Windows). However, OS/2 3.0 probably won't be seen be- fore 1992. And when it does appear, it just might go by another name — -Win- dows-32, perhaps. But will the indus- try become mired in the present API by then? According to some rumors, OS/2 3.0 will be able to run Win- dows, OS/2, and POSIX applications on screen in separate windows simul- taneously. But what sort of system resources will be required to do so? Will we have 50-MHz CPU's and 16Mb D RAM's by then? If so, maybe performance won't matter, but if not... Windows 3.1 A more immediate topic of spec- ulation has been Windows 3.1, originally due around mid-year, but now third or fourth quarter. Expected features include smaller size and bet- ter speed, a built-in type-scaling/font- management system called True- Type, multimedia extensions, an im- proved File Manager, support for stylus- based input, and a Windows- specific version of BASIC. To get a taste for the latter, check out Word- BASIC, the amazingly powerful "macro" language in Word for Win- dows. Borland should release a ver- sion of Turbo Pascal for Windows sometime this year as well. Windows now When Windows 3.0 first came out, I found it interesting and enjoyable — but somewhat impractical. However, gradually throughout the past year, I have migrated more and more of my activity there, so that now I spend 90% of my computer time running Windows, The other 10% is used al- most entirely for two things; system backup (to an Irwin tape drive) and file management (with Lotus' Magellan). 80 R-E Computer Admart Rates: Ads are WxPtf. One insertion $995 each. Six insertions $950 each. TWelve insertions $925 each. Closing date same as regular rate card. Send order with remittance to Computer Admart, Radio-Electronics Magazine, 500-B Bi-County Blvd., Farmingdale, NV 11735. Direct telephone inquiries to Arline Fishman, area code-1-516-293-30Q0. FAX 1-516-293-3115. Only 100% Computer ads are accepted tor this Admart. GETTING THE MOST FROM YOUR PRINTER G»t ting The Most Front Your Printer BP181— It is probable that 80% of dot-ma- trix printer users only ever use 20% of the features offered by their pf inters. This book will help you unlock the special features and capabilities that you probably don't even know exist. To order your copy send $6.95 plus $1.50 for shipping in the U.S. to Elec- tronic Technology Today Inc.. P.O. Box 240, Massapequa Park, NY 11762-0240. In the past I've mentioned my big three Windows applications: Word for Windows, Corel Draw, and CrossTalk for Windows. Now I'd like to discuss some of the other applica- tions and utilities, large and small, that have allowed me to make this migration. Best spreadsheet: Excel 3.0 was built specifically for Win3, hence is better integrated than the current versions of Word For Windows and Project. Excel 3,0 has several irre- sistible new features including spreadsheet outlining, powerful drawing tools (something I expect to see in the next version of WinWord), much-improved charting (including 3D graphs), an autosum function that intelligently figures out the correct horizontal or vertical sum function, and full support for different type faces, styles, and sizes. The program includes several add-on packages, in- cluding a goal-seeking function that works backward from results to modi- fy an equation that generates said results, and a database query tool that allows you to query a local or networked database. Most useful utility: I've men- tioned it before, but Adobe's ATM (Adobe Type Manager) neatly and cleanly solves one of Windows' big- gest problems: font management. ATM brings the ideal of WYSIWYG (what you see is what you get) closer to reality by an order of magnitude. With ATM, you can print text in any SECRETS OF THE COMMODORE 64 Scrtta Of tlU COMHODOBt (.4 BP13S — A beginners guide to the Commodore 64 pre- sents masses of useful data and programming tips, as well as describing how to get the best from the powerful sound and graph- ics facilities. We look at how the memory is organized, random numbers and ways of generating them, graphics-color-and sim- ple animation, and even a chapter on ma- chine code. Get your copy today. Send $5.00 plus $1.25 for shipping in the U.S. to Electronic Techology Today Inc., P.O. Box 240, Massapequa Park, NY 11762-0240. UT GLL Q*i FEU-EX QflD€H£ received ay. m t-t iLuik ft *■ i''* 1 * CM AVAILABLE M»StBrC«rd VISA nr UPS CASH COO MICROPROCESSORS UNLIMITED IMC SS&ftSSr (918)267-4961 CIRCLE 61 ON FREE INFORMATION CARD PostScript font on any dot-matrix, ink-jet, or laser printer and, re- gardless of the printer, see an accu- rate representation on-screen. You can develop your document in your office with a PostScript laser printer, take the document on the road and print it on a portable ink-jet, work on it at home with a dot-matrix, and produce final copy on a Linotronic typesetting machine. In all cases, vou can simply switch drivers and not worry about font availability on the target printer. And regardless of the output device, the document will print identically, within the physical limits of the device. For example, if you call for a 30-point headline in Helvetica. XGA UPDATE Last time I made some off-the-cuff remarks about IBM's XGA video adapter. It turns out that IBM really is serious about making XGA a new standard. Last month the company made two important announcements on this subject. (1) In addition to the Micro Channel (PS/2) bus version, there will be an AT-bus version of the XGA adapter. (2) IBM will sell XGA chip sets to OEM's who can then build it on their own boards and sell it. These are significant changes in IBM's marketing direction, and will ensure that XGA assumes VGA's cur- rent role as standard bearer. Look for XGA boards to appear in late 1991 or early 1992. R-E whether you print it on a 9-pin Epson or a 2540 dpi Linotronic, you'll get 30- point Helvetica. Microsoft's own TrueType, developed in conjunction with Apple, will incorporate ATM -like features directly in Windows. ATM lists for $99 and is available through mail-order distributors for about $60. Highest recommendation. Best file manager: Becker- Tools 2,0 is the best I've found. It's crammed with useful utilities (copy, delete, move, format, edit, etc.) and customization options (see Fig. 1). BT2 works better than Windows' own File manager, and it does so in a man- ner familiar to users of MS-DOS file managers. The program does not al- ways follow Windows' user- interface guidelines, and is simply awkward in others. It has a "pack" function for compressing files, but does not use a standard format; the program should allow optional use of an external pro- gram (PKZIP or your favorite), and better control over compressed files. $129.95 from Abacus, 5370 52nd Street SE, Grand Rapids. Ml 49502-8107. C800) 451-4319; C616) 698-0330. Tutorial/games: Microsoft has released a Productivity Pack for Win- dows that contains a tutorial on using Windows. Novices to whom I've rec- ommended it say that it's a big help. Microsoft has also released an Enter- tainment Pack that contains several games and one of the better screen blankers on the market. c 2 <$ S 81 i n FCC NO-CODE AMATEUR RADIO LICENSE The FCC recently passed Docket 90- 55 which for the first time allows a new codeless entry ham radio license of technician grade. Privileges 30 MHz and above — All modes! (See R.E. ar- ticle in April 1991 issue). Get all the no-code license details, study & testing information plus a one- year subscription to one of ham radio's longest running specialty mode publi- cations that will teach you all about the new modes you will be able to operate! FSTV SSTV FAX RTTY PACKET AMTOR OSCA R FM REPEA TERS MICROWAVE AND LOTS MORE! SEND $25 CHECK OR MONEY ORDER / Sl'l-'( '-'('. I <•< OUR 24TH YEAR SINCE 1967! I The SPEC-COM Journal P.O. Box 1002, Dubuque, IA 52004 (319)557-8791 MC/VISA (5% addBtJ) B ts — % \ I mmmmmmimi^mmmm Your Ticket To | SUCCESS J Over 28,000 technicians have gained admit- I tance worldwide as certified professionals. I Let your ticket start opening doors for you. I ISCET offers Journeyman certification in ■ Consumer Electronics, Industrial, Medical, I Communications, Radar, Computer and | Video, For more information, contact the ■ International Society of Certified Electro- I nics Technicians, 2708 West Berry Street, | Fort Worth, TX 76109; 1817) 921-9101. y I Name Add ress City , __ State . Zip to O Z o Ii > (-qr— | icm ^ll^ I -H +■;■ 4 |CEZ3 Lo flHRS L : ^z-: i I — I |CUlNB|[inr<>1 jEi^[5HSl [a^a |b?llS,||BH B«B E3 C r=] nn ife. nt ii II \ ii ■■ ATMF0NTS t COREL PM PSF0NTS TIFFANY TOOLBOOK WINDOWS <0IR> WINHISC WINWORD FREC0UER BAK 50S88 FRECOUER DAT 50688 FREC0UER IDX 29 + Q«SbE3 ;i. ....... id r»~ rs- Ii &. ir\ II • ARCS t BPT DOS EZTflPE LANTASTI LANTASTI NET LOTUS mea, HFT NORTON PC INDEX PCPLUS PRO PROG SIDEKICK SLEUTH + Files: 0/3 Dirs: 0/9 Files: 20 Dirs: 19 Entries: 39 FIG. 1 — EteekerTools 2.0 is the beat file manager I've found. It's crammed with useful utilities and customization options. It works better than Windows' own File manager, and it does so in a manner familiar to users of MS-DOS file managers. Public domain and share- ware utilities: Pickings here are pretty slim at present (another paral- lel to 1 981 ). However, I have located a few gems that I now load automat- ically via the LOAD = lineinWIN.INI. CHIPS AHOY! Mention 386 and people think Intel. However, that may change and soon. AMD has demonstrated a 386 clone that may take some of the wind out of Intel's sales {pun intended), and thereby provide better prices and per- formance for end users. The AM386 is 100% compatible, but is built en- tirety from CMOS, so power con- sumption runs 33-66% less than an Intel 386. In addition, a "steep" mode allows the clock to stop, dropping power consumption to about 1 mA. The AM386 will be released in 25- and 40-MHz versions: there are claims that the 40-MHz version runs as fast as a 33-MHz 486. If AMD can find the legal wherewithal to market its clone, it will bust the laptop/porta- ble market wide open. Real systems should be released this spring. In retaliation, Intel will release sev- eral "crippled," lower-cost versions of the 486, one without the math coprocessor, one without the cache. In addition to fighting the doners, this gives Intel a chance to sell 486s that don't pass final inspection. RE They'll be posted on the RE-BBS C516-293-2283. 1200/2400, 8N1). • WinExit: Exit quickly from Windows simply by double-clicking on an icon. • Digital: Formatted display of time, date, available memory, disk space. • WinClock: Time/date display, in- cludes alarms, count-down timers. • IconLib: 200 icons for various pro- grams, stored in a single EXE file. • Click: Adds keyboard click. • ZM: ZIP File Manager. Functions as a shell for PKZIP, PKUNZIP, and several other compression schemes. Buggy and doesn't use the Windows interface effectively, but saves shell- ing to DOS. If you'd like to keep track of share- ware/PD offerings but don't relish the thought of scanning BBS's and on-line services, check out the Public Software Library. The company main- tains a well-organized collection of software for DOS, Windows, and OS/2 (and the Macintosh), which it distributes for$5/disk. Every program in the library has been reviewed; descriptions are avail- able in printed and electronic format. PSL publishes a monthly newsletter, the PSL News, describing new and updated programs. Subscriptions are $24/year. For more information, con- tact PSL at P.O. Box 35705, Houston. TX 77235-5705, (800) 2424-PSL. (713) 524-6394. R-E MARKET CENTER FOR SALE TUBES: "oldest," "latest." Parts, and schematics. SASE for lists. STEINMETZ, 7519 Maplewood Ave., RE. Hammond. IN 46324. RESTRICTED technical information: Electronic sur- veillance, schematics, locksmithing. covert sci- ences, hacking, etc. Huge selection. Free brochures. MENTOR-Z, Drawer 1549. Asbury Park, NJ 07712. CLASSIFIED AD ORDER FORM To run your own classified ad, put one word on each of the tines below and send this form 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 S25.00. ( ) Plans/Kits ( ) Business Opportunities ( ) For Sale ( ) 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) 23 ($86.80) 4 9 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 WITH OUT THIS INFORMATION WILL NOT BE ACCEPTED. CLASSIFIED COMMERCIAL RATE: (for firms or individuals offering commercial products or services) S3. 10 per word prepaid (no charge tor zip code) -MINIMUM 15 WORDS. 5% discount for same ad in 6 issues; 10% discount for same ao 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) 55e per word additional. Entire ad in boldface, S3. 70 per word. TINT SCREEN BEHIND ENTIRE AD: S3. 85 per word. TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD: S4.50 per word. EXPANDED TYPE AD: S4.70 per word prepaid. Entire ad in boldface, $5.60 per word. TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD: S5.90 per word TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD PLUS ALL BOLD FACE AD: S6.80 per word. DISPLAY ADS: 1" x 2V<"— $410.00; 2" X 2W— S820.00; 3" x 2 '.■'■■.'— S 1230. 00. General Information: Frequency rates and prepayment discounts are available. ALL COPY SUBJECT TO PUBLISHERS APPROVAL. 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 5th of the third month preceding the date 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. CABLE TV converters: Jerrold, Oak, Scientific At- lantic. Zenith & many others. "New MTS" stereo add-on: mute & volume. Ideal lor 400 and 450 owners! 1 (BOO) 826-7623, Amex, Visa, M/C accept- ed, B & B INC., 4030 Beau-D-Rue Drive, Eagan. MN 55122. TUBES, new, up to 90% off, SASE, KIR BY, 298 West Carmel Drive. Carmei, IN 46032. CABLE TV converters and descramblers. We sell only (he best. Low prices. SB-3 $79.00. We ship C.O.D. Free catalog. ACE PRODUCTS, P0 Box 582, Dept. E, Saco, ME 04072. 1 (800) 234-072S. 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. TV. notch filters, phone recording equipment, bro- chure S1 .00. MICRO THinc, Box 63/6025, Mar- gate. FL 33063. (305) 752-9202. TOCOM VIP converters w/remotes from S299.00. TOCOM PREMIUM SUPER CHIPS from $49.00 turn on everything, guaranteed. Phone (219) 935-4128 Evenings 6-1 2PM EST. __ LMR's, CB/amateur, scanners, radar detectors, auto alarms, rotors, catalog S2.00. RAYS, Box 14B62, Fort Worth, TX 76117-0662. TEST equipment pre-owned now at affordable prices. Signal generators from $50.00, os- cilloscopes from $50.00, otherequipment.including manuals available. Send $2.00 U.S. for catalog. refunded on 1st Order. J.B. ELECTRONICS, 3446 Dempster. Skokie, IL 60076. (708) 982-1973. CALL DOCTOR DESCRAMBLER ...for symptoms relating to scrambled cable T.V. signals. We have • JERROLD • TOCOM • ZENITH • HAMLIN «0AK • SCIENTIFIC ATLANTA. Six month warranty! We ship C.O.D. Lowest retail/ wholesale prices. FREE CATALOG: VISA, M.C., AM.EX. Global Cable Network 1032 Irving St. Suite 109 S.F., CA 94122 NO CALIFORNIA SALES"! OPEN SATURDAYS 1-80M356730 83 Quality Microwave TV Antennas • I WIRELESS M8LE - IFTS - MMDS - Amateur TV J UIM High Gain MdlJl+l • TuneiUe 1.9 lo 2.7 Ghi. [ J . 36-Chanral Syslem Compltle S 1 4S.S5 • 12-Channel Syslim Complale (114.95 . Call or write (SASEl for 'TREE" Catalog M PHILLIPS-TECH ELECTRONICS |^K«f P.O. Bos 8533 . Scottsdale, AI 85252 lifetime (60S) 947-7700 [M.OO Credit all pftone orteri) WARRANTY MunrCwd • Wn • COD'i «• DISCOUNT computer books: Thousands of titles available. Including recent releases. Please call or write for your free catalog BOOK WARE, 344 Wa- tertown Road, Thomaston, CT 06787 1 (800) 283-5662. (303) 283-6973. KNOW the phone number of the person calling you before answering, S79.95, brochure S1.00, surveillance catalog, S5.00, EDE, POB 337, Buf- falo, NY 1422S. CB RADIO OWNERS! 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. CEC INTERNATIONAL P.O. BOX 31500RE, PHOENIX, AZ 85046 ENGINEERING software, PC/MSD0S. Hob- byists — students — engineers. Circuit de- sign and drawing, PCB layout, Logic simulation, FFT analysis, Mathematics, Cir- cuit analysis. Call or write for free catalog. 1 (800) 728-3805, BS0FT SOFTWARE, 444 Colton Rd., Columbus, OH 43207. DESCRAMBLERS, Oak R.T.C-56 $140.00, Tocom 5503A $199.00, Oak X-12 $49.00, Z-Tac $225.00, Hamlin CRX-6600 $125.00, Super Tri-Bi — SA-3B $79.00, Sylvania 4040 replaces Jerrold 400-DIC $89.00. All others in stock. MOUNT HOOD ELECTRONICS (503) 253-0459. CABLE descramblers, Oak X-12, Tocom 5503A, Oak RTC-56, Zenith Z-Tac, Syl- vania 4040, Hamlin 6600 — MLD 1200, SA-3B — Super Tri-Bi top quality, best prices, volume discounts, best warranty, C.O.D. orders OK. S.A.C., 1 (800) 622-3799. WIRELESS CABLE RECEIVERS 1,9 TO 2.7 GHz □ JO CH PARABOLIC DISH SYSTEM $173 90 30 CH ROD ANTENNA SYSTEM (193.90 3D CH CRYSTAL CONTROLLED S1T5TEM SS. Include cabbage, broccoli,. brussels sprouts, kohlrabi and cauliflower, 4, De moderate in consump- tion of salt-cured, smoked, and nitritC'Cured foods. 5« Cut down on total fat in- take from animal sources and fats and oils. 6. Avoid obesity. 7» Be moderate in consump- tion of alcoholic beverages No one faces cancer alone . P AMERICAN GAHCBt SOCJeTY ***** STARRING ***** JERROLD, HAMLIN, OAK AND QTHt?R FAMOUS WtAlSfUFACTUHERS • FINEST WARRANTY PROGRAM AVAILABLE ■ LOWEST RETAIL I WHOLESALE PRICES IN U.S. • ORDERS SHIPPED FROM STOCK WrTHrW 24 HRS • ALL MAJOR CREDIT CARDS ACCEPTED FOR FREE CATALOG ONLY V8O0-3 4-5-89 2 7 FOR ALL INFORMATION I-B18>709-99'37j PACIFIC CABLE CO.. INC. 7325V! Reseda Blud., Dept. 2103 Reseda, CA 91335 CONVERTERS all major brands info I orders 1 (800) 782-0552 FREEWAY INC. (s.m.p), PO 5036. Burnsville, MN 55337, No MN Sales, BETTER TV reception, bargain prices!!! Do It your- self, send LSASE for price list of many home TV anfenna and MATV products, DAI, Box 335, High- way 925N. Waldorf, MD 20601. FREE catalog. Connectors: Centronics, serial, au- dio, rf. Cables: shielded, coax, ribbon. Plus more. PO Box 121575B, Fort Worth, TX, 76121. 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. ADULT video tapes 90 min. VHS Current color vid- eos assorted titles 1 — $10.00 3 — $25.00. Free shipping. STRINGSOFT, Box 91S-R. Old Bridge. NJ 08857. TECHNICIANS. The ultimate test lead, jumper ca- bleswith switch $14.95 each. MHA, PO Box 152797, San Diego, CA 92195, INVENTORS INVENTORS! Can you patent and profit from your idea? Call AMERICAN INVENTORS CORPORA- TION for free information. Over a decade of service 1 (800) 338-5656. In Canada call (413) 568-3753. HARD TO FIND HARD to find discontinued electronic parts. We Specialize commercial & miliary. WESTERN COM- PONENTS, [805) 245-2727. (805) 245-2208. 84 DISTINCTIVE RING SWITCH Add additional phone numbers to a single linewith the new Distinctive Hinging service from the phone company. Ring Director detects ring patterns and routes calls to phones, answe ringmachines, FAX'S or mod ems. 2- port $89. 4-port $149. S/H $5. 1 -800-677-7969 FAX 51 6-676-9225 EXCELLENT TECHNOLOGY 69 smith street, Clen Head, NY1154S SATELLITE TV PLANS AND KITS DAZER personal protectors! Lasers! AM FU In- 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, New Orleans, LA 70131 . DESCRAMBLING, new secret manual. Build your own descramblers for cable and subscription TV. Instructions, schematics for SSAVI, gated sync, sinewave, (HBO, Cinemax, Showtime, UHF, adult) $12.95, $2.00 postage. CABLETRONICS, Box 30502R, Belhesda, MD 20824. REMOTE CONTROL KEYCHAIN Complete wJirU n(-tf«n»ra titer ;,::.: ; end +S vdc R F receiver Fully assembled including plan* to build your own auto alarm Qua n U ty cti sco unts & vai I a b\ e Ani n c Check.Vlsa or M'C ;J>Z4.yC>;: AddSSshipfrfna V1SITECT INC.80X S4«, SO, SAN FRAN , C A, 04080 (415)531-8425 Fax (415) 531-8442 SMD How to use surface mount technology. Build ultra miniature projects. Plans included free, inlra 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! Four models of each; telephone, room, combination telephone/ room transmitters tune from 65 to 305 MHz. Catalog with Popular Communications and Popular Electronics book reviews of "Electronic Eaves- dropping Equipment Design," $2.00. SHEFFIELD ELECTRONICS. 7223 Stony Island Ave., Chicago, IL 60649-2806. 4.ASER& New Laser Diodes $15 Helium- Neon Laser Tubes from *2S COMPLETE HELIUM-NEON LASERS FROM S590O FREE CATALOG Call or Write Today ! MEREDITH INSTRUMENTS P0 ShiWGHMm UMJiiwaHMSF ROBOTICS! Engines! Inventions! Muscle wires contract wilh surprising strength when powered. Send business SASE for latest flyer. MONDO-TRO- NICS c/o RE, 2476 Verna Ct.. San Leandro, CA 94577. FREE cable and satellite descrambler plans. Send self addressed stamped envelope. MJM tNDUS- TRY, Box 531, Bronx, NY 10461-0208. KITS, games, sounds light effects. Send $1.00 JM ELECTRONICS, PO Box 150454, Altomonte Springs, FL 32715-0454. LASER, construct the ND-337 mega watt nitrogen and visible dye laser system. Nitrogen laser pumps dye laser. Very simple construction. Uses no mir- rors. Plans $15.00, INFO TECH, 537 Aero, Shreveport. LA 71107. BUY BONDS FREE catalog — Lowest prices worldwide, save 40 — 60%. Systems, upgrades, parts, all major brands factory fresh and warranted. SKYVISION, 2009 Collegeway, Fergus Falls, MN 56537. 1 (800) 334-6455. I'LL HAVE MINE DESCRAMBLED '<$£> If you find a better deal, We'll beat It! JERR0LD • TOCOM • HAMLIN • OAK • SCIENTIFIC ATLANTA • ZENTTH • ask about our warranty program C.O.D. Visa, M/C, AM.Ex. welcome. 'FREE CATALOG • FREE CALL •OPETT SATURDAYS 1 800 562-6884 VIDEO TECH 3702 S. Virginia St. Ste. 160-304 Reno, KV 89502 CABLE TV Secrets — the outlaw publication the cable companies tried to ban. HBO, Movie Channel, Showtime, descramblers, converters, etc. Sup- pliers list included. S9. 95. CABLE FACTS, Box 711- R, Pataskala, OH 43062. ROM THE FOLLOWING PACKAGES: PKG.'I... 10 PANASONIC 1453G CONVERTERS $65" PKG. "2... 8 SCIENTIFIC ATLANTA $17C 8536+ COMBINATIONS v If vl PKG. '3... 5 SCIENTIFIC ATLANTA $0H E* 8580 COMBINATIONS L Id PKG. '4... 10 MIX AND MATCH ADD-ONS $45' ALL EQUIPMENT IS BRAND NEW, FACTORY FRESH III ( s^' 1006 M UW Cable Descramblers New Auto Tri-lti guaranteed no flashing $165-1 ZENITH SUreR SAAV1 1199,00 TOCOM 1315.00 EAGLE, - J119.00 COPY GUARD SS9.95 STARGATE 2000.,, 588,00 SB-3_ $99.00 TR1MODE S 109.00 HAMLIN... 599.00 SCIENTIFIC. ATLANTA 5119.00 OAK M35B 599.00 ZENITH 5175.00 M.I). Electronics will match or beat an; advertised wholesale or retail price. Your hest buys and warranties for cable converters and desc ram biers start with a FREE catalog from Ml) For Information Call 402-554-0417 To order or request a free catalog 1-800-624-1150 EXCELLERATOR CABLE CONVERTERS WHEN QUALITY COUNTS New Dynatrack™ Tint tuning provides unmatched picture quality 550 Mhz tuner provides 83 channel capacity Sleep timer for automatic shut off within 15-90 minutes 2/3 swllchable HRC i IRC / Standard Switchablc 2 Year Warranty] Last channel recall s Favorite channel select, Scan Double vented high efficiency transformer Tor cool performance Stargate-2001 $99.00 $targate-550XL $1 19.00 With Volume Control Don't settle for anything less, SB c.o.d. 873 SO. 72nd 5t OfTMih*, NE 6STV* IT OHDDUNC C A1LE TV 'BQLTFMINT HUH U fl SUCTSOSKS TTni PL"KJl«EJt AGUES TO COMPLY WITH ALL STAfi AND (■"£ GEKAL LAWS RECAKCC4G PEJVaTE| OWN-OSIHP C* CA1! £ TV BQUTPMET EF ¥OU AJK& UKSURfi OP THESt EXWS C WITH YOUR ICCM OFFICIALS CIRCLE 53 ON FREE INFORMATION CARD 85 FREE CATALOG! 1-800-648-7938 JERROLD HAMLIN OAK ETC CABLE TV Special Dealer Prices! Compare our Low Retail Prices! Guaranteed Prices & Warranties! * Orders Shipped Immediately! REPUBLIC CABLE PRODUCTS, INC. 3 4080 Paradise Rd. #15, DeptRE691 ri 3 Us Vegas, nv 89109 t^J For all other information (702) 362-9026 CABLE TV DESCRAMBLER LIQUIDATION! FREE CATALOGI Hamlin Combos 144, Oak M35B $60 (min. 51, etc. WEST COAST ELECTRONICS For Information: 818-709-1758 Catalogs & Orders: 800-628-9656 VIDEOCYPHER II descrambling manual. Sche- matics, video and audio. Explains DES, Eprom, Clonemaster, 3Musketeer, Pay-per-view (HBO, Cin- emax, Showtime, adult, etc.) $16.95, $2.00 postage. Schematics for Videocypher Plus, $20.00. Sche- matics for Videocypher 032, $15.00. Collection of software to copy and alter Eprom codes, $25.00. CABLETRONICS, Box 30502R, Bethesda, MD 20824 VIDEOCIPHER II manuals. Volume 1 — Hardware, Volume 2 — Software — either $34.95. Volume 3 — Projects/Software, Volume 5 — Documentation or Volume 6 — Experimentation $44.95 each. Vol- ume 7 — 032/Hacking $54.95. Volume 4 — Repair $99.95 VC Primer — $9.95 Scanner Hacker's Bible — $34.95 Cable Hacker's Bible — $34.95. Satellite Hacker's Bible — $54.95. Catalog — $3.00. CODs (602) 782-2316. TELECODE, PO Box 6426-RE. Yuma. AZ 85366-6426. 3 It Ku satellite system. Legally receive free TV programs and pictures of current events. Systems as law as $599.00. Call or write MOONBEAM SAT- ELLITE, PO Box 429, Mastic Beach, NY 11951. (516) 281-2669. ELECTRONIC ASSEMBLY BUSINESS Stan home, spare time. Investmenl knowledge or experience unnecessary. BIG DEMAND assem- bling electronic devices. Sales dandled by profes- sionals. Unusual business opportunity. FREE: Coraplele illustrated literature BARTARE0OBUX248 Walnul Creek Caiil. 94597 BUSINESS OPPORTUNITIES MAKE $50/hr working evenings or weekends in your own electronics business. Send for free facts. MJME INDUSTRY, Box 531, Bronx, NY 10461-0208. YOUR own radio station! AM, FM, TV, cable. Li- censed/unlicensed. BROADCASTING, Box 130- F6, Paradise, CA 95967. LET the government finance your small business. Grants 'loans to $500,000. Free recorded message: (707) 449-8600. (KS1). PERFECT CABLE CONNECTION !! Perfect Cable Connection is lotally committed to customer satisfaction Our primary concern Is to provide you with the highest quality converters and descramblers at (he lowest cost. We employ Full time technicians to ensure hassle Iree service and troubleshoot any siluation. Call us today and let us prove to you why we are Ihe Perfect Cable Connection. ■ 6 months 100% parts & labor ■ 24 months warranty available ■ Full technical support - On-line computer system ■ 3D days money back guarantee ■ Most orders shipped within 24 hours ■ Visa, M'C, AMEX - 5% • Dealers welcome ■ C.O.D. Jertoid SA 6Ste WR flegai RC S3 Wfl " *W" i-. *i « 11 i ■ . 400DRX3 DIC Wfl i B9 ■ 99 Ch capatwly 1 i'. 1 119 10 69 ■ Wireless remote '. t-i S 89 20 65 - Automalic line lurwig 1Q Jj) to ?g 50 60 ■ Parental lode 20 69 1M 55 ■ Mada in Japan 50 65 ■ Slcvvtoi 100 CALL ■ Favonle memory tJwineK CHX MUD JM w n JcMDlrJ CA 450 DHZ 3 p*C Wfi 1 129 199 Zenith ZTACS i ris <> CA i.A 5 99 ID 89 20 79 ."0 154 CAlL All irton^i Call lor prices to GO CM 50 CALL 100 S0 CAll 10O CALX 100 CALL a tl J SA-3B FTB-3 DRX 3105 WR i P4 1 75 JSO IJH/ i W H 1 99 1 S5 90 jg. 10 4a i ij| 10 79 S 49 .fi S.\ 20 « hi '.;. 20 55 10 « • I H SO 39 .11 f. 50 CALL £0 40 too 35 100 CALL o z i r- b UJ 6 i 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 ^^inadki MZlEEtfUniCS 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 step bit). Add yourself to our user files to increase your access. Communicate with other R-E leaders. Leave your comments on R-E with the SY50P. RE-BBS 516-293-2283 MAKE 575,000 to $250,000 yearly or more fixing IBM color monitors [and most brands). No invest- ment. Start doing it from your home. (A telephone required.) Information, USA, Canada 51,00 cash. US funds, other countries $8.00 RANDALL DIS- PLAY, Box 2168-R, Van Nuys, CA 91404 USA EASY work! Excellent pay! Assemble products at home. Call for information (504) 641-8003 Ext. 5192, MAKE SSS! Become an American electronics deal- er! Profit opportunities since 1965. Call SCOTT PRUETT, 1 (800) B72-1373. FREE CATALOG! 1-800-348-7659 ELECTRONIC COMPONENTS, AUDIO, VIDEO, TELEPHONE, ANTENNA £ ACCESSORIES, Ptjtylwi Cewe . Zfl Cwrjhit Rg . PO B0* 1Q33. EMt Blurry***. MJ flBftJC Video Transceiver Digital Video Stabilizer En« rrw mcrM nj £S? "<^ 'IK «F*fl,tO^l0 IBMVWtltl / ELECTECH / CABLE T.V. DESCRAMBLERS • All quality brand names • • All fully guaranteed • All the time ■ Knowledgeable Sales Service Department FOR FREE CATALOG 800-253-0099 BEST BY MAIL Rates: Write National, Box 5, Sarasota. FL 34230 OF INTEREST TO ALL CITIZEN BAND RADIO DXing. Get more out oi your radio. Catalog S1.00. C6R, Box 212, Roche lie Park, NJ 07662. BUSINESS OPPORTUNITIES $2,750 WEEKLYl CALL 1-900-988-5162, Ext. #130. S3.00 per minute. EDUCATION & INSTRUCTION F.C.C. Commercial General Radiotelephone li- cense. Electronics home study. Fast, inexpensive! "Free" details. COMMAND, D-176, Box 2824, San Francisco. CA 94126. MAGIC! Four illustrated lessons plus inside infor- mation shows you how. We provide almost 50 tricks including equipment for lour professional effects. You gel a binder to keep the materials in, and aone- Kear membership in the International Performing tegictans with a plastic membership card that has your name gold-embossed. You get a one-year sub- scription to our quarterly newsletter "IT'S MAGIC!" O rde r now ! $29 . 95 (or each cou rse + $3.50 postag e and handling. (New York residents add applicable state and local sales tax). THE MAGIC COURSE, 500-B BiCounty Boulevard, Farmingdale, NY 11735. LEARN IBM PC assembly language. SO pro- grams. Disk $5.00. Book S18.00. ZIPFAST, Box 12238, Lexington, KY 40581-2238. BUILD VCR extender quickly. Construction guide shows new, inexpensive method to transmit reliable VCR pictures in home over existing telephone wires. Easy, fun, practical. No complicated transmitters, receivers. Complete, with technical description. VCR Extender, $19.95, JZO RESEARCH, Box 28131, Minneapolis, MN 55428. 86 LOGIC ANALYZER continued from page 38 a controller chip. Coupled with a standard low-power SRAM, the SmartSocket provides all of the benefits of standard non-volatile memory. The logic analyzer cur- rently uses a 32K x 8-RAM. The TTL levels of the V25 are converted to RS-232 levels by IC41, a Maxim MAX232 RS-232 transceiver. The part requires only a + 5-volt supply and has in- tegral charge-pttmps to create the necessary - 10-volt and + 10 volt RS-232 levels. The negative contrast-voltage for the LCD panel is generated by IC42, also a MAX232 chip. The V25 address and control lines are decoded by IC44 and IC20 to pro- duce device selects for the memo- ry, LCD, and control registers. A programmable logic device (PLD) from Lattice Semiconductor, IC44, (a GAL16V8) produces the control signals required by the LCD panel. It also generates the RAM and ROM chip selects. The chip selects for the registers which control the logic analyzer section are produced by IC20. The LCD is a 240x64 pixel graphics display with built in RAM. controller, and micro- processor interface. That display allows the logic analyzer to run a true windowed graphics inter- face under the control of the V25. The TL7705 is a reset and power-supply monitor circuit. It produces a glitch-free reset sig- nal on power up. It will also reset if the drops below 4.75 volts. Each IC on the circuit board is de-coupled using a 0.1 ^F capaci- tor. That is shown in the large capacitor array in Fig. 6. The power supply uses a standard three- terminal voltage regulator. IC43, Because the logic analyzer draws approximately 600 mA, a TO-3 type case and heat sink are used. The analyzer is powered from a plug-in wall transformer which supplies an unregulated 9 volts DC. Note that the logic analyzer can also run off batteries. Six D- cell alkaline batteries will run the analyzer for over eight hours. Next month when we continue, we'll show you how to build the logic analyzer, and how to use it to troubleshoot circuits. R-E JDOsonn tohelpAmeric . prepare for future. Support America's colleges. Because college is more than a place where young people are preparing for their future. k 7 s where America — and American business — is preparing for its future. Give to the college of your choice. w.,,*^ m, OF % 12" Subwoofer Box 12" Pioneer Subwoofer 800 Hz Horn 18" Eminence Woofer The perfect high volume cabinet for dual voice coil subwoofers. Box comes with pre-cut woofer and port holes. Cabinet volume: 2 cu it. with dual ports. Charcoal carpet Dimensions: 1 3" (H) k 13" |D) x 30" (W). Net weight: 29 Ids. #RH-260-495 $59 90 Each 12" Pyle Woofer pyLE 12", 70 oz magnet woofer- 2-1/2" voice coil. 10Swafts RMS, 155watts max power handling capability. CO PIONEER' 12" super duty, dual voice coil subwoofer. 30 oz. magnet, 2" voice coil. 100 watts RMS, 145 watts max power handling capability, 6 ohm impedance (4 and 6 ohm compafcbSe)- Sensitivity: B9dB1W/1M. Response: 25 700 Hz. QTS^ ,31 r VAS= 10 3cuH. Mel wecghl: 6 lbs. Pioneer #A30GU30-55D #RH-290-145 $39 K $36 80 (1-3) (4-up) 5-1/2" Cone Midrange Original Sanyo high end system midrange. Large 5" paper cone with gold look dust cap. Heavy 1 2 oz. magnet, 1"ferro fluid cooled voice coil. 50 watts RMS, 75 watts max. Sanyo pan #S12H 10. Mel weight; 1-1'2 lbs. £j» Pieio midrange^tweeter driver unit. Response: 900-20 KHz. Power handling capability: 20-30 volts {approximately 50 watts RMS) Sensitivity: 93 dB, 2.83W1M. 4" round. Motorola #KSN10BS. #RH-270-085 $25 30 $23 (1-3) (4-up) 95 Professional driver lor use in auditorium and studio sound systems. Giant 100 oz. magnet. 250 watts RMS, 350 watts max power handling capability. fs= 30 Hz, QMS= 3.17, QES= .373, QTS= .33. VAS= 10.5 cu ft SPL. 95dB1W/1M. Net weight; 29 lbs. EMINENCE #RH-290-200 $99 S0 $93 40 [1-3) (*-up) #RH-292-050 S62- 10 (1-5) $59 80 (6-up) #RH-281-100 SASYO $5- $3 95 (1-9) <10-up) Subwoofer Crossover Network Super duty, 200 watt RMS power handling capability. Designed specially for dual voice coil subwoofer systems. 12dG per octave fol't-olf al S*^, 150 Hz into 3 ohms. Crossover also Features a set of outputs for use wilh your existing speaker system. Network is totally passive, requiring no power source of its own. #RH-260-220 $28 80 $24 95 (1-5) (6-up) Br Parts '/express % ■15 day money back guarantee • SI 5.00 minimum ofdet • We accept Mastercard, Visa, Discover, and C.O.D. orders. - 24 hour shipping • Shipping charge -UPS chart rale + S1 .00 (S3.0O minimum charge) • Hours B30 am - 7:00 pm EST. 340 E. First St.. Dayton, Ohio 45402 Monday - Friday ■ 9:00 am ■ 2:00 pm Saturday. Mail order Local: 1-513-222-0173 FAX: 513-222-4644 CALL TOLL FREE customers, please call lor shipping estimate on orders exceeding 5 lbs. | ■OUU'OJO"UDO I Foreign customers ptease send $5.00 U.S. funds lor catalog postage. FREE CATALOG CIRCLE 56 ON FREE INFORMATION CARD CABLE TV EQUIPMENT Converters, Remote Controls, Descrsmblers, CD Players. JERROLD-OAK-SCIENTIFIC ATI-ANT A-1IAMLIN ZENITH MANY MORE CALL TODAY! V Only quality products sold V Easy to use V Satisfaction guaranteed V Knowledgeable sales staff V Most orders shipped within 24 hours CALL FOR YOUR FREE CATALOG 1-800-228-7404 MAKE THE CONNECTION WITH NU-TEK ELECTRONICS || 5114 Balcones Wood Dr.#307 Dept.298 Austin, TX. 78759 ZENITH & TOCOM SPECIALS SUPER Zenith (Z-TAC) converters (flashing)... $179.00. Zenith "turn-on" module... $49.00. Tocom 5503(A) converters... $559.00. Tocom (add-on) descramblers . . S79.00. Tocom (5503- VIP 4 5507) "turn-on" chips... $49. 00. Tocom 5507 se- curity screw removal bits...S22.00. C1NEPLEX VID- EO GROUP. 1 (800) 726-4627. WHY RENT ! Compare and Save ■ Lowest Prices 30 DAY MONEY BACK GUARANTEE - ONE YEAR WARRANTY Fjree Tech Support Service - Extended Warranty Program Voted #A in Customer Satisfaction iERMlD SRKM 6 8 7 Baseband Panasonic - Zenith ■ Oak ■ Hamlin Scientific Atlanta - Tocom • Etc. Dealers Wanted - Quantity Discounts COD's - VISA - MC - Discover - American Express All Orders and Free Catalogs Cable Specialists, Inc. East Coast - Canada West Coast (800) 334-94941(800) 666-9494 1T53C E. PiMse EM., St; 431 3133 Sheridan st:«t. Ste, 112 Frtndile, C» 33SS) Heaivwood, Ft 33021 ANTIQUE RADIO CLASSIFIED Free Sample! Antique Radio's Largest Circulation Monthly. Articles, Ads & Classifieds. 6-Month Trial: $13. 1-Yr: $24 ($36-1 st Class). A.R.C., P.O. BOX 802-L6, Carlisle, MA 01741 WANTED INVENTIONS/ new products/ideas wanted: call TLCI for tree information 1 (800) 468-7200 24 hours? day- USA/Canada. INVENTORS: We submit ideas to industry. Find out what we can do for you. 1 (800) 288-1DEA. NEED help with your electronic project, PCB as- sembly.'arfwork? Write to T.S., PO Box 5275, Flint, Ml 46505. INVENTORS! Your first step is importanl. For free advice, call ADVANCED PATENT SERVICES. Washington. DC, 1 (800) 458-0352. TRAVEL! High income! Radio officers wanted for shipboard employment. Must have FCC second telegraph license. Rae Echols, AMERICAN RADIO ASSOCIATION, 5700 Hammonds Ferry, Linthieum, MD 21090. [Great money in VCR repair f] Home study. Learn high-protit repairs B without investing in high-tech instruments. j*-^o3j>\ . | FREE BOOKLET-. B0O-223-4542. I ArlriiMit f . V I I City State Zip The School of VCR Repair, 2245 Perimete ■ Park. Dept.vG342, Atlanta, Georgia 3034 CABLE DESCRAMBLERS OAK M35B COMBO S39.S5 Jerrold. Zenith, Hamlin. Sci. Atlanta, Pioneer 8 MORE! OUR PRICES ARE BELOW WHOLESALE! CABLE+PLUB 14417 Chase St. #481-A Panorama City, CA 91402 1-800-822-9955 • Other Info. 1-818-785-4500 NO CALIF SALES - DEALERS WANTED PAY TV AND SATELLITE OESCFtAMBUNG AIL HEW 1991 EDITION Our best yet The very latest in descramDiung drcufts, Bypasses. [urn-ons lgr abH. wireless and ateirrte. Only $1 *.%. onw pay TV editions. Vol . 1 (Baste at All Srtl*r s i $1 a .95 m* EtJiTJon 3 1 4.9S. Build sau-ute systems under S60Q £12.95 Wirefess Cable HandaooV S9.95 toy 3iS29.!p5 ar 5rSM.» Scnmhlirnj News Monthly rms ill into on me new -ftim Vjmlli" descramblers which em- ulate B-Wac. VCII Plus and Orion. $19.&iyr. All ntvi cajalog $1. Scrambling News, 1552 Hertel Ave.. Bui laic. NY. 14216 CODS ARE OK. (716) B74-20a.lt CO O z o rr h- o Lit _l til 6 < 88 UMCORN - YOUR LC. SOURCE & MUCH, MUCH MORE! Laser Diode * Output 3 mW (max,} Laser Diode • Output- 5 mW ima*.] Laser Diode ■ Qutpur * mW (ma* f Laser Diode ' Output 5 mW (max.) Laser Diode ■ Output 3mW [max.) (.vis rble-red) • Cu rreni : as- 1 do hi a (visible red) * Current: 65-10C mA (vj si ble red ) * Current- 20 m A { visible red ) * Currant 6TJ mA [Infra-red) • Current: S5-1D0 mA ~ *Op VcJt.: 2.3-3 ,0V ^ ■ Op. VoJL: 1.75-2.2V fit ~X\ ■ Wavehenglh:7aONM i £~ : * Lens Rcaur/eftf A£» • Qp. Volt : 2..V3 0V -«a ' Op Volt 2.3-3 0« •Op. Volt, 23-3 0V fti 8V _ » waveienaiiv 67QNM ^ ^\ \*^. * Waveleflgth^ 670NM ^J— * — * Wavdleriglh 670NM / • Wa vecngth 320NM \ 1 t i"~ " '- eri9 RBqUIHHJ ii L—~ ■ Lens Ketjuirea -*Lf= ' Lens Required J k. t • Lens Requited vGmJrf ■ Data Sheet & ^ -flf ■ Data Sh«t & yLmm^ff * Data Sheei & VsG ©^ ■ Data Sheet A • Data ShMI rnc Application notes inc Application notes mc Application notes «nc Application noles mc. STOCK # PRICE STOCK 8 PRICE STOC K # PR IC E STOC K # PRICE STOCK f. PHICE LS9200 $49.99 LS022 $19.99 SB3200 S89.99 LS9211 $69,99 SB1053 S9.99 Collimator Pen Laser Pointer Power Supply {Infrg-red) -. • Output: £.5 mW ■imajt. ifS. ' Current.: 9Q-15Q mA ^^JN* ■ Op Volt.: 2 2-2.SV * Output: 35 mW / • WavrHer.gth: 670NM ^ * Power Supply: 2XAW jfr Sallenes jinctLhCni!d|i ^^fc • input: 115/Z3QV Lrmjms . STOCKS »-24 25-99 100+ STOCK* 1-24 25-99 1004 1702 4.59 4.3S 3.92 2764A 349 3 32 299 ^^^^ ■ Wavelength %wnm jfr • Beam: Appro*. 3" fffl 1QQ ■ Size: 7™ L X SW" W 270S 6.49 6.17 5.55 TMS2564 5.79 5.50 4 95 ^■v&h ■ Data Sftnel ir»e JF yards x 2»" H 2716 3.29 3.13 262 27C64 3.29 3.13 3 28 ^F" . Ouanlaty Discounts 271 6-1 3.79 3.60 324 27128-20 4.99 4 74 4.27 Available TMS2716 5.79 5.50 4.95 27128 4.79 4,55 4.09 STOCK # PRICE STOCK # PRICE STOCK # PRICE 27C16 2732 3.99 4 19 3.79 3.98 3.41 3.58 27 128* 27C126 4 79 4.79 4,55 4 55 4.09 409 LB1052 $39.99 LSPOINT $199.99 19.99 2732A-! 3.79 3.60 3 24 27258-20 5.29 503 4.S3 2732A 3.69 3.51 3 16 27256 4.79 4.55 4 09 Disc Drive & Computer Disc Drive Head- Anti-Static 273SA-4 3.19 3.03 2.73 27C2S6 4.29 4 08 367 Cleaning Kit Cleaning Kit Screen Wipes TMS2532 TMS2532P 579 1.99 550 1.39 495 1,70 27512-26 27S12 649 699 617 5.69 555 5.12 ■Slot ju&t a drive cleaner- mm^mmymr* Includes cleaning "Kit S6.99 SB1100 SVTKit $6.99 STOCK # PF SB1105 W Drive Kit S1 SB1106 5'.V r Drive Kit $1 wrapped Canon 2764A-20 399 3.79 341 66766 DYNAMIC RAM 1299 1234 11.11 STOCK # PRICE ,CE SB1104 Dispenser pack .99 ol 25 wipes .99 SB1106 Dispenser pack ot 100 wipes 1 STOCK" 1-24 25-99 loot STOCK i 1-24 25-99 100- MK4027 4116-120 4116-150 59 1.39 99 56 1-32 94 .50 1.18 85 4464-100 4464-120 4464-150 299 2.79 2 29 284 265 213 2 56 239 4ffMtfc 1 96 W54* ■ZT^lTS^t-ll: 4116-200 09 .85 .77 41256-60 2.99 284 2.56 SKI P_^ 10010CanogaAk'e..UnitB-8 • Ch atsworth , C A SI 31 1 Vim OUTSIDE CALIFORNIA: (S00) 824-3432 (Orders Only) wm 7 IN CALIFORNIA: (B18) 341-8833 4116-250 4164-100 .59 56 180 50 1.63 41256-60 4 1256-100 2 79 199 265 L89 239 1.70 * 1 BS ,'1 UNICORN ■ *J 11 t c i ■ o n it s B 4164-120 4164-150 4164-200 1 1 1 by 59 ■■:, 1.61: LSI 1.32 1.55 1.36 1.19 41256-120 41266-150 511000-70 1.89 1 79 649 180 170 6.17 1 63 1 63 5.55 ORDER BY FAX: (818) 998-7975 4416-120 1 99 1.89 1.70 511000-80 5.99 5 69 S.12 Minimum Order S15.0D * 24-haur ordering available 4416-150 1 79 1.70 1.53 5110O0-100 5.49 5 22 4 70 CIRCLE 183 ON FREE INFORMATION CARD : .. a J KWSJ SLOMA | rnrf„ cz: S cs @iii E^ CODE SCANNER Compact uni copies Morse, HTTY, ASCII codes from your radio on 32 character LCD display. Ten day money back. Model CSCAN $189.00 + SS S&H MICROCRAFT P.O. Box 513R Thiensville, Wl 53092 Telephone (414) 241-8144 CABLE T.V, CONVERTERS WHY PAY A HIGH MONTHLY FEE? All Jerrold, Oak, Hamlin, Zenith, Scientific Atlanta, Magnavox and all specialized cable equipment available for shipment within 24 hours. For fast service MC/ VISA or CO. D. telephone orders accepted (800) 648-3030 60 Day Guarantee (Quantity Discounts) 8 A.M. to 5 P.M. C.S.T, CLOSED WEEK- ENDS. Send self-addressed Stamped enve- lope (60s postage) for Catalog. , L„„eW RfctaBOM Till BPKtCOtrllNHjTItl At A WVOLK SEnVKE When someone in your family gets cancer, everyone in your family needs help. Nobody- knows better than wc do how much help and understandings needed. Tlut's why our service and rctnbiliacion p a $ r a i ri ■■ emphasize (he whole family ixfl jusc ihe canter pintni. Among our regular services v.-c provider information and giikianrtctopaiLcnwind families, iranspori patients 10 and from l rcitment. supply hqme care items and isiisi patients in thetr return to everyday life. Life is w hj.i concerns us. 5u you Can See we are even. more than the research organi- zation we are so well known 10 he. No one faces cance r alone. V AMERICAN CANCEfl SOCIETY WARNING! CABLE BOX DEALERS Consider the facts before you buy after-market cable equipment An industry standard defines 25% of all after-market cable boxes do not work when first tested... All wholesalers advertise low prices. ..but low prices are not enough. Any price is too high if you're without technical support or quality control. Now consider that your success as a dealer depends on the satisfaction of your customers. Wholesale Cable Supply offers services that are near a defined science. And we guarantee 100% satisfaction. Monthly Special • Guaranteed Low Prices " • State-of-the-Art technical support • Top Quality Tested Products • Dealer Market Support WHOLESALE CABLE SUPPLY Low Price is only the beginning 1-800-926-6836 723 CAMINO PLAZA, STE. 108, SAN BRUNO, CA 94066 TB-3 or SA-3B 10 lot 48 20 lot -43 50 lot -39 100 lot -39 Z-TAC 10 lot - 149 MARK V €l€CTRONICS, INC. Competitive Pricing * Fast Shipping Since 1985 ORDER IN CALIFORNIA 800-521 -MARK ORDER OUTSIDE CA 800-423-FIVE FREE CATALOG & INFORMATION (213) 888-8988 FAX (213) 888-6868 indicates the level of difficulty in the assembling of our Products Amplifier A Beginner A A Intermediate AAA Advanced * Metal Cabinet + Transformer Kit Set Assmb. Set TA-3600 LG-1925 #007 $1 55.61 $179.36 TA-477 LG-1925 #003 $125.21 $141.36 TA-802 LG-1924 #001 $100.45 $113.54 TA-1000A LG-1924 #001 $113.52 $133.36 Due to mis special offer 1 lew price, we can only exchange or repair any ol Ihese units (TA-3600. TA-477, TA-802 & TA -1 0QQA) wllttin 1 5 days of your receiol. The above pnees arc lor she complete sets For separale unit price, please see below Transformer Fully Assembled *"- TA-1QQ0A VUWfef $1 30.00 5150,00 AMPLIFIERS KIT ASSEMB, MISCELLANEOUS KIT ASSEMB. MODEL TA-2BMK2 TA-S0AIB TA-S0C TA-120MK2 TA-300 SM-302 IA-323A TA-377A TA-4O0 tA-477 TA-MMMK! TA-802 lA-IMuA TA-I500 TA-2200 TA-24SJOA I A :•:,>:-. "■'-.'!■ TA-30O0 TA-3600 SM-52? SM-328 SM-333 SM-E66 SM8M DESCRIPTION Digital Voire Memo u _.„ , . Multi- Purpose Melodv General or A Mow- Pur pose Melody [Happy BiMhflay. Wedding March, Etc.) Generator 35W Class 'A 1 Main Power Mono Amp. ii .. _t _ 30WMulli-Puipose Single Channel Amp A . -- , - » SOW • 60W Sleree Power Amplifier (with MIC. inmli AA , 30WX 2SEereoPreniarn Amp a Stale 01 the An fully Complementer,' Symmetrical FET Pre Amp AAA 40W Solid Slate Mono Amp A 120W Moslet Power Mono Amp AA . . 120W . 120W low Tim Pit-Mam Slereo Power Amp. AA _ _ _ Mrw . SOW Pare DC Stereo Main Power Amp AA . S3C0C . 12 84 A 13.65 31 SO 20.00 57 00 31 SO 59.95 28 00 68 GO 63 92 45 94 100W Dynamic Class 'A' Mam Power Mono Amp. AA 100W K 2 Class 'A' DC Stereo Pre-Main Amp AAA DC Fel Super Class 'A - DC Pre-Amp AAA .... Electronic Echo £ sieve) Deration Amp. - 73 70 . 4770 |'D Pre-Amp wi'10 band g i a,i 'in equalLrer * STFn ID Pre-Amp w*3 way lone control AA . Slereo Stmulilor iFcr Mooe TV or Any Mono Source! A A . HOW HD HiTi Power Mono Amp AAA } Band HI-FI Graphic Egualmr AAA 4 Channel Professional Dolor f ig.hl Controller* AudierVldCO Sui round Sound Processor AAA* Dynamic Maise Reduction A Urmergl AudnaVKieo KARAOKF Mixe? Pre-Amp * 43 90 .27 00 85 00 2690 KE 26.00 17.20 18.71 4380 29 00 78.00 4280 75.00 34.93 85.00 53 72 ■BOSS 0581 53 24 96 00 68 SO 63 57 38 50 11000 3880 145.00 75 00 34.00 225 CO MODEL 1Y-238 TY-25 IY-3S TV- 36 TK-38 TY-41MKV TY-,2 TY-43 TYJ5 TT-47 lO.OOOairt DESCRIPTION 3 Channel Cotot Light Controller * . Stereo Loudspeaker Prosector A FM Wireless Microphone A AC/DC Quarti Digital Clock A Sound I Touch Control Switch A . Inlrared Remote Control Linn (wrCasel AAA BjrrQoUewt Meter aa 3'.,- Digital Panel Meier A 2s) Steps Bar i Dot Audio Level Display a a .. Superior Electronic Rpolelle AA , 80 V Capacitor {Suggested lor TA-JEDO. TA-477. TA-IOO0A £ TA-802) 14.85 , 11.25 19.00 12.00 2200 .24.15 29 00 . 33 45 . 19.16 $65.00 20.95 26 20 35.00 3381 3800 46.14 27.24 23 00 REGULATORS KIT ASSEMB. "Sl-3tS* TS-355B TR503 0-15V 5A Regulaled DC Power Supply mo case £ * former! A 0-3OV 3A Regulaled DC Power Supply '. no case £ t rprmert A 0-5OV 3A Regulaled DC Power Supply |no case £ * former! A A .$15.65 S2175 15,65 21 76 . 16 75 23.65 METAL CABINETS WITH ALUMINUM PANEL MODEL LG-1273 LG-1684 LG-1924 LG-1925 LG-1983 iflO' MATCHING 12" r TA-2SQO.TA-377ATA-2200 ir r TA-323A.TA.3T7A TA-2J00 1ST 11 "i TA-802. TA-t500,TA!2OMK 2 TA-100MK2 TA-100OA 19' II') TA-477.TA-SO0.MK2. TA-1500, TA-IOOOA TA-3600 ... ■19' 8- TA-377A,.TA-28O0,TA-22D0,1A-l20MK2 PRICE S 22.85 27 50 3280 35 BO 29 2S POWER TRANSFORMERS DIGITAL METERS AND COUNTER KIT ASSEMB SM'43 SM-4S SM4SA 5M-49 SM 100 FC-1000A 3 j Multifunctional L ed D P.M (w/AIJS plaslic asel A A 4^ Hi-Precision DP M AAA 4U Hi-Piecision D PM iu.'AUS PDSIlccaselAAA 3'".- Mull i- Functional LCD D M P [w'Hold Fnncl.oniA A 150MC Oujitat Frcduency Counter AAA 1 GKj Frepueney Coimler * ^ . S 34.50 . 38.00 . 41 20 38 00 7900 S4300 4S.00 52.00 44.50 90.00 S7900 MODEL .?-' 002 003 004 005 006 007 DESCRIPTION 2SV>26A1o30Vi26A 36V 1 2 3A 40V>2 6A 24V 1 2 EA 26VK2 3A 1SVI2 5A 53VI2SA WATCHING PRICE TA.800MK2 TA.302. iA-S20A. TA-IOO0A TA-15O0 S 27.00 TR-503.TA-323ATA-400.TA-300 TA-3J7A .22.00 TA-477... 28 00 TA-120MK2 .. 2? CO TR.355B ... -. .._ .. 18.00 IR-355A ISM TA-3600 . ..43 00 C to CD 89 >tmjHi MARK V ELECTRONICS, INC. - 8019 E. Slauson Ave, Mootebello, CA 90640 -=-E3IISi CIHCLE 93 ON FREE INFORMATION CARD tn o z o DC H Q :u _i LU 6 < We Have QUALITY PARTS • We Have DISCOUNT PRICES * We SHIP FAST mimimmmm 24 Vac MINIATURE GEAR MOTOR Maxon DC motor # 2130 910 61.1 12 060 Raling wilh no load: 24 Vde©5ma-1B8RPM 12 Vdc @ 5 ma -84 HPM Precision gear motor. Designed for 24 Vdc Operates on 1 2-24 Vdc. 30:1 gear reduction head- 2.07 long X 1.10' square mounting brack - el has mounting holes on 0.97" centers. Motor has good torque when used at 24 Vdc. CAT* MOTG-15 112.00 each I.E.C. POWER CORD 12 Vdc POWER PACK FLOURESCENT FIXTUR* 6 foot BLACK, SPH-3B6 jack to 3 prong molded A.C. plug. Fits most computers, computer terminals and test equipment. CATKLCAC-C6 $3 00 each 12 Vdc 1 Amp. power pack. 8 ft, 2 conductor pwoer cord on input. 22" cord with stripped and tinned pigtail leads on output. 3.2* X 2.3* X 1 .9". CAT#DCTX-121 $5.75 each Fixture lor single mini bi-pin 6*. 4 watt lluores cent lamp. Starter switch, sockets and ballas are mounted on. 7 1/4" X 3 1/4" metal pi ale. Includes 8 toot power cord with strain relief. Use with standard iluoreecent lamp lor displa lighting or with ultraviolet lamp for special el- leas or EPROM erasure. U,L listed. CAT#FLX-1 $3.00 each SWITCHES Dip P.C. Push button ITT Schadow Digitasl Series SE S.P.D.T. momentary pushbutton. Mounts in 14 pin DIP configuration. Designed for how current switching appli- cations. Grey keycap is 0.63" X 0.67V CAT#PB-28 It. 00 each 10 tor 19.50 ■ 100 tor $85.00 Mercury Tilt Switch 0.2" diameter — X 0.65" long mercury II rt switch, S.P.S.T .Closes circuit when switch is tilted approx. 5 degrees. CAT»MS-3 St .CO each 10 for $9.50 - 1 00 (or $85.00 Rotary BCD Switch rrz^ BCD 10 position V 2 ^ rotary switch, DIP configuration fits in standard 8 pin I.C. socket. Bight angle style. Screwdriver actuation. 0.42* cube. CAT*RDIP-2 $1 .75 each 10 lor *1 6.00 - 100 for* 146.00 Miniature Toggle* Bated: 3 amps @ 120 Vac S.P.D.T. (QN-ON) P.C. mount CAT*MTS-*PC SI. 00 each 3 10 for $8.00 - 100 for $80.00 jf S.P.D.T. (ON-ON) solder lugs jfe cat#mts-« S 1.35 each Op 10 lor $12.50- 100 lor ill 0.00 ^f D.P.D.T. (ON-ON) solder lugs CAT*MTS-8 SI.75oa. 101or$15.00 D.P.D.T. (ON-ON) P.C. mount CAT*MTS-8PC $2,00 ea. 10 for $17.50 TELEPHONE KEYPAD 12 button telephone keypad. Ivory finish. 2.83- X 2.2" X 0.58" thick. Matrix encoded. Ideal lor telephone or security keypad. CAT*KPT-I$1,00each 10 for $9.00 OPTO-SENSOR TRW/Optron * OPB5447-2 IR emitter/sensor pair In Reel ang ular package with 23" color coded leads. CAT*OSFM 2 lor $1,00 'ff^yna PH0T0FLASH CAPACITOR Rubicon CE e~E "3 210 Mfd 330 Volt f===3 phototlash capacitor. *■— ' 0.79" dia. X 1.1" high. These are new capacitors that have been prepped with 1.4" black and red wire leads soldered to the termlnaJs. CAT*PPC-210 $1.25 each- 10 tor $11.00 100 for $100.00 Large quantities available. Call tor pricing. RECHARGEABLE BATTERIES 6 Volt 1 Amp/Hour Japan Storage Bafiery Co. Ponalac jsm***^ *PE8V1 ^££"25 6 Vol 1 Ah Pn I rechargeable J sealed lead-acid ~— -^ (gellcell). 2" X 1 .635" X 2" ht. Batteries are prepped with 5" black and red leads termlrta- ed with 2 pin connector, CAT#GC«1 $4.75 each 10 tor $42.50 Nickel-Cad AAA SIZE $1.50 each 1.2 volts 180 mAh CAT* NC8-AAA AA SIZE $2.00 each 1.25 volts 500 mAh CAT* NCB-AA AA SIZE $2.20 each WITH SOLDER TABS CAT* NCB-SAA CSIZE $4.25 each 1.2volls 1200 mAh CAT* NCB-C DSIZE $4.50 each t.2 votts 1200 mAh CAT* NCB-D HALL EFFECT SENSOR P.C. RELAYS Microswitch *5S41 Tiny, solid stale switch reacts Instantly lo proximity of magnetic field. Operates at extremely high speeds, up to 100 khz. Case size; 0.12" X 0.17" X 0.06" thick. 4.5 Vdc to 24 Vdc suppfy voltage. 10 ma. sink type digital output. Operating gauss - 15 to 40. P.C. leads. CAT* HESW-3 $1.00 each ■ 1 for $9.00 100 lor $85.00 • 1000 for $750.00 INSTRUMENT ENCLOSURES ^ ^ High Quality molded ABS instrument enclosures, integrated PC board siandotfs and two sets ol vertical mounting slots, lor front and fsar sub panels, AH enclosures are 6" wide X 6 1/4" deep. Choice of three his, Irvdudes non-skid rubber leei and hardware. Available in beige. Ivory, black, and blue. Pini ht CAT* 21«" CATffMB-A S7 50f*ch 10twM50Q 2 &S- CAT* M 9- 8 $7.75 Bit*. 1 tar (67 50 3" CAT* HB-C iS CO *.rtch 1 tar $70.00 Please speedy color. RG-11/U VIDEO CABLE 100 tt. or 200 ft. rolls of RG 11/1175 ohm cable terminated to heavy duty F connectors. Includes 75ohmtefminatorand • • IMlXl F-61 splicer on one end. New cables manufactured for IBM PC networks. IBM P/N 150 1908 COM/SCOPE. CAT*RG-1t-1 100ft.roll$15.00 C AT* RG-t t -2 200 ft. roll $27.50 FLASH ASSEMBLY New compact flash assemby from a U.S. manufacturer of cameras. Operates on 3 Vdc and measures QTZ 2 1/2" x 1 1/4". Idea] for use as a strobe. warning lighi or attention getter. Includes hook-up diagram. CAT*FSH-1 $3.75 each 101or $35.00- 100 for $325.00 The following relays ail have p.c. pins lor both Input and output as well as quick-connect terminals on the output, 1.5" X 1.05" X1.0B". UL&CS A listed. 12 Vdc. SPDT Potter & B rumf laid * T91R5D22- 12-02 12 Vdc, 155 ohm coil. Normally open contacts rat- ed 20 amps. Normally closed contacts rated 1 amps. CAT* RLY-31 $2.50 each 10 for $22.50 12 Vdc. SPST rt O. Potter & Brumfield* T91R5022- 12-01 12Vdc.155ohmcoil. S.P.S.T. normally open con- tacts rated 30 amps. CAT* RLY-32 $2.00 each 10 lor $18.00 L.E.D.S Standard JUMBO [ Diffused T 1 -3/4 size (5 mm) RED CAT*LED-1 10lor$1,50- 100 for $13.00 GREEN CATtfLED-2 10for$2.00- 100 tor $17.00 YELLOW CAT* LED-3 10 for $2.00 ■ 100 for $17.00 FLASHING LED W built in flashing circuit 5 TO* operation. T 1-3M (5 mm) r ^^^^ FED $1.00 each CAT* LED 4 10 for $9.50 GREEN $1.00 each CAT* LED-4G1010/ $9,50 YELLOW $1.00 each CAT*LED-4Y10tor$9.50 LED HOLDER Two piece holder. « e CAT*HLED 10for65« LED. FLASHER KIT Two L .E. D.'s f Irah In v m /^ tU/ u nison when a 9 volt '3~ m battery is attached. This kit Includes a p.c. board, all the pans and instructions to make a simple Hash er circuit, A quick and easy project lor anyone with basic soldering skills. C AT* LED KIT $1 .75 per kit LE.D. CHASER KIT Build this variable speed led chaser. 10 leds flash sequentialy at whatever speed you set them for. Easy to build kit includes pc board, parts and instructions. Ideal lor special lighting effects, costumes, etc. Oper- ates on 3 to 9 volts. PC board is 5' X 2.25". A great one hour project. CAT*AEC $6.50 each STEPPING MOTOR CONTROLLER KIT Learn about stepping motors while building this sinpie circuit. Includes circuit board, stepping motor and all parts except 12 Vdc power supply. CAT* SMKIT $1 8.00 each METRONOME KIT This simple device can be set to clck ■mm 20 to 1 .000 beals per minute. Easy lo build, includes circus board, al components and instructions. Oper- ates on a 9 voh battery (not included]. CAT* METRO S3 J5 each PHOTO RESISTOR 1 ,000 ohms bright Eight. 5^ 16K ohms da*. IT 0.182- dia. X .08"hlgh. 0.18' long lead: CAT* PHE-7 2 lor $1.00 100!or$45,00'10001or$400.00 ORDER TOLL FREE 1-800-826-5432 FAX (818) 781-2653 Call Or Write For Our Free 60 Page Catalog INFORMATION (818) 904-0524 Outside the U.S.A. send $2.00 postage for a catalog. Minimum Order $10.00 »M Orders Can Be Charged To Visa, Mastercard Or Discovercard • Checks and Money Orders Accepted By Mail • 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 90 CIRCLE 107 ON FREE INFORMATION CARD ORDER DIRECT 1-415-770-2345 FAX DIRECT 1-415-770-2346 CCH TRIPP LITE - PRECISION REGULATED DC POWER SUPPLIES Complete Line of DC Power Supplies to Convert 120vAC to 1 3.8vDC ±0.5vDC. Standard Features Include: •Solid state integrated circuit provides excellent regulation. •Output voltage maintained up to 95% of no load value. •High quality filtering for low noise operation. ■Heavy duty power transformer for complete line isolation. •On/Off indicator light and rugged on/oil switch on faceplate. •3 conductor grounded cord on 10 amp and larger models. ■Current limiting electronic foldback for auto overcurrent protection. Tripp Lite DC Power Supplies Are Designed For Reliability and Superior Performance. PR25 Order « Price PR45 PR7 PR10 PR1S 32.95 44.95 64.95 89.95 ics- (amps) PR25 126.95 4.5 7 10 15 25 Continuous Duty (amps! 3 5 7.5 12 20 Fus ino internal Chassis Mount Chassis Mount Chassis Mount Chassis Mount Ripple Voltnge HxWxDtlnches) 0.1 volt max. 0.15volt max. 0,15volt max. 0.15 volt max. 3.125x4.75x8.25 3.75x6.5x7.5 4.5 x 6.525 x 7.625 4.75 X 7.5 X 8.25 Weight 0.15 volt max. 5.125x12.5x10.5 5 lbs. 7 lbs. 10 lbs. 13 lbs. 20 lbs. •Intermittent Communications Duty (50% Duty Cycle) SOLDERLESS PROTOTYPING BOARDS SE400 FEATURES "Color coordinates for easy recognition 'Insertion wire: 20-29 AWG (0.3 - 0.8 mm) 'Over 10,000 insertion cycles "Accepts all standard components nn SB830 SB 1060 SB3220 Price Price Dimensions (In.) Dist Order # 1-9 10+ LxWxH Strip SB200 2.99 2.49 6.5x0.37x0.4 2 SB400 4.S9 4.39 3.3 X 2.2 X 0,4 2 SB630 5.49 4.99 6.5 xt. 4x0. 4 SBB30 6.49 5.99 6.5 x 2.2 x 0.4 2 SB1360 12.49 11.99 8.5x3.9x1.2 1 SB1660 17.49 16.99 8.5x5.1 x 1.2 4 SB2390 22.49 21.99 9,1x6.9x1.2 5 SB 3220 31.49 30.99 9.5x3.3x1.2 7 Dist, Points 100x2 100 200 100 400 500 700 Terminal Strips DATABOOKS Motorola RF Device Data - Vol. 1 & 2 This two volume set contains over 2200 pages of data on RF Power TMOS 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 ail packages. Weight: 4.25 Ibs. Order#DL110 14.95 Terminal Points 300 630 630 1.260 1,260 1,890 2,520 Binding Posts Motorola Memory Data Over 500 pages on Dynamic RAMS, General and Fast Static RAMS. MOS EEPROM, MECL Memories, etc. Weight: 1 .25 lbs. Order * DL1 13 8.95 Motorola MPU/MCU/Peripheral Data - Vol. 1 & 2 Over 2800 pages on Motorola's Microcontroller and Microprocessor families such as Ihe MC6800, MC6802. MC6821, MC6845, MC146818, MC68701. MC68705, etc. Weight: 4.0 lbs. Order #DL139 16.95 National General Purpose Devices Linear Data book Over 1600 pages on voltage regulators, operational amplifiers, buffers, voltage comparators and instrumentation amplifiers. Weight: 3 lbs. Order #400026 19.9S National Programmable Logic Devices Databook Over 400 pages including data sheets, designing with PLDs, methodology and developmental tools. Also included is an introductory tutorial section. Weight: 1 .0 lb. Order #400081 12.95 Extensive range of parts & components in stock. ORDER DIRECT 1 -41 5-770-2345 FAX DIRECT 1-415-770-2346 ACTIVE COMPONENTS MICROS DRAMS Order # Price Order # Price Desc. 6821 1.75 MK4027N2 ..... .75 4x1 6845 2.49 4116-20 85 16x1 B080A 2.95 4416-12 2.95 16x4 8085A 2.95 4164-10 1.95 64x1 6066 4.45 4164-15 1.75 64x1 8088 4.75 4164-20 1.25 64x1 8237 A5 4.25 41464-12. 2.75 64x4 8250 5.7S 41256-80 2.75 256x1 8251A 2.25 41256-12 2.15 256x1 8253-5 2.75 514256-10 7,95 256x4 8255A5 2.95 511000-80 8.75 1Mx1 8275 1S.95 511000-10 8.25 1Mx1 STATIC RAMS Ord er # .Price 2101 .1.65 2114L25 1.39 2147-3 3.75 6116LP3 2.95 6116-3 ,....2.45 6264LP10 5.25 6264LP15 3.95 6264-10 4.75 6264-15 3.75 62256LP10....7.95 622S6LP15 . 6.95 E PROMS Order #_ Price 2708 4.95 2716 3.45 2732 3.95 2732A25 3.45 2732B45 4.25 2764-25 3.75 2764 A25 3.25 27128A25 3.95 27256-25 4.75 27256-30 3.45 27C512-15 6.95 Prog. 25V 25V 25V 21V 12.5V 21V 12.5V 12.5V 12.5V 12,5V 12.5V MEMORY MODULES-SIMMS Order* Price 256x9-80 1x9-80 19.95 69.95 Organization Speed 262,144x9 1 .048,576x9 SOns 80ns MISCELLANEOUS ICs Order # Price Description AM 29 843 DC 2.95 D7220D 12.95 D7261AD 19.95 FD1793PL02 8.95 LM345K5.0 6.95 NS16450N 6.25 N80L286-8 14.95 WD1 943 4.95 Z0800110PSD 19.50 Z0803008PSD 9.50 9-Bit Buf, Latch - Non Inv, Graphics Display Cont, Hard Disk Cont, (12Mhz) Disk Drive Controller 5V Meg. Voll Reg. 3 Amp Asynch. Comm. Element 16-Bit CPU (8Mhz)PLCC Dual Baud Rate Gen. Segmented CPU (10Mhz) Serial Comm. Cont. (8Mhz) 2917 Bayview Drive Fremont, CA 94538 Order Direct: 1-415-770-2345 Fax Direct: 1-415-770-2346 Monday-Friday, 7am - 5pm (PSTyi0am-8pm (EST) [T| VISA \T\ MasterCard R1 COD-No personal checks, US funds ($5.00 Charge) [Tj USPS \J\ UPS \J\ Airborne Express Add 5% of total for shipping charges ($3.00 min.) Call or write today to reserve your free copy of our 1991 catalog due in July 1991. "California residents, add appropriate sales tax. *12 month warranty on all EasyTech producls, '30 day money back guarantee. "We reserve the right to substitute manufacturers. "Prices subject to change without notice. CIRCLE 177 ON FREE INFORMATION CARD C Z m to 91 Perfectly Tuned for Test/Measurement and Prototype Equipment 51-Piece Electronic Tool Kit Global Specialties Protoboard® Design Station Tools Included in Kit: 10' measuring tape 535' needle nose pliers Electric tape Utility components box 6 piece precision screwdriver sel 6" long tweezers 8 piece hex key wrench set 7" brush and scraper Digital Multimeter Brush 7" line point probe Round needle lile 10 piece screwdriver set: 6 Slotted & 4 Phillips 7" slotted probe Flat needle file 4.5* diagonal cutting pliers MS305 6" adjustable wrench 30 Watl soldering iron 5.5" Stainless steel scissors Soldering sland Rosin core solder 5.25* Flat nose pliers Utility knife wilh extra blade Desoldering pump 5,25" Bent needle nose pliers Carrying case: 17.63"Wx12.5 - Dxl5-H $119.95 Jameco Logic Pulser Jameco Logic Probe • Compatible with TTL. DTL. RTL. HTL, HNIL, MOS and CMOS ICs • 1M(J Sync Input impedance • Pulser mode output current: 10mA + Square wave current output: 5mA ■ Audible tone LP540 $16.95 PROTOTYPING PHODUCTS Jameco Solder! ess Breadboards Contact B In ding Points Pes it. Price JE21 3.25*2.125 400 $4. 95 JE23 6.5 x 2.125 930 $6.95 JEZ4 6.5 x 3.125 1.360 2 St 2.95 JE25 6.5 x 4.25 1.560 3 $17.95 JE26 6.875x5.75 2.390 4 $22.95 JE27 7.25 k 7.5 3.220 4 $32.95 * Max Frequency BQMHz ■ Minimum delectable pulse: 1Qn& * 120K£i inpul impedance * Max. supply vDFtage: *25V * TTL threshold: (Lo)+0.3V iO.1V (Hi) *2.3V ±0,2V ■ CMOS threshold: (Lo) 30% VCC .-10% (Hi) 70%VCC ±10% MS104 $24.95 Metex Digital Multimeters General Specs: - Handheld, high accuracy ■ AC/DC voltage. AC'DC current, resistance. diodes, continuity, transistor hFE • Manual ranging w overload protection M3650&M4650only: ■ Also measure frequency and capacitance M4&5G only; • Data hold switch * 4 5 digit. M3610 3.5 Digit Mirtilmeler S59.95 M36S0 '3.5 Digit MuJlimetw w- Frequency S Capacitance » ..*..* 374,95 M4650 4.5 Digit ^'Frequency. Capacitance and Data Hold Switch .«.«.. $99.95 Handheld Multimeter J AMECO 24 Hour Order Hotline (415)592-8097 FAX: (415) 592-2503 (415)595-2664 • Partial sS Features: ■ Ideal for analog, digital and microprocessor circuits ■ Triple DC regulated power supplies, +5V, + 15V, -15V ■ 8 logic indicators • Function generator with sine, square, triangle and TTL waveforms PB503 • Two debounced push-button switches • Two SPOT slide switches, all leads available and uncommited ■ A total of 2520 uncommited tie-points ■ Potentiometers: one 1KQ and one 1 0Kil • Includes power supply, instrumentation and breadboarding $299.95 A.R.T. EPROM Programmer • Programs all current EPROMs in the 2716 to 27512 range plus the X2B64 EEPROM •RS232 port • Software included EPP $199.95 UVP EPROM Eraser r* r ■ Erases all EPROMs ■ Erases 1 chip In 15 minutes and 8 chips in 21 min •UV intensity: 6800 UW/CM 2 DE4 .$89.95 EPROMs - for your programming needs Part Ho. Price Part No. Price 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 6.95 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 27C1 28-15 27C1 28-25 $3.95 3.75 3.49 3.95 3.25 3.95 3.25 2.95 6,95 4.95 5.95 4.49 4.25 5,95 6.49 Part No. Price 272560TP $3.75 27256-15 5.95 27256-20 5.25 27256-25 4.75 27C256-15 5,95 1 27C256-20 4.95 27C256-25 4.49 2751 20TP 4.95 27512-20 6.95 27512-25 5.95 27C512-15 6.95 27C512-20 6.49 27C512-25 5.95 1 27C010-15 11.95 68766-35 9.95 ■ 3.5 dig.il LCD wilh automatic polarity indication ■ AC'DC voltage measurement up to 500 volls . AC;DC current measurement up ID 200mA ■ Resistance measurement up to 20MH . Con- tinuity checker with audible tone » Diode and logic tester ■ Aulo/manual range and data hold functions ■ All range protection and lunction in- dications Soldering and Desoldering Stations SO Watt Analog Display Soldering Station - Electronic temperature control from 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 DMM905 $39.95 XY999 $299.95 Listing ■ Over 4000 Electronic and Computer Components in Stock! CIRCLE 114 ON FREE INFORMATION CARD Top Performance. Computer Products and Electronic Components J AMECO 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 functions ■ In-depth assembly instructions included ■ Have your new computer assembled and running in an evening, using common tools • Software included ■ Purchase computer kits configured by Jameco or design your own 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.S" DSHD floppy disk drive • Baby sized desktop case • 200 Watt power supply ■ DR DOS 5.0 by Digital Research and Diagson's QAPIus diagnostic software ^H? mor* " ■aba*" e Hard Drives Conner (1 6-bit IDE) CP3044 40MB 3.5" Low Profile .$469.95 CP31 84 BOMB 3.5-HH... $649.95 CP3104 100MB 35"HH ,$699.95 AD P20 Most Adapter $29 .95 Relisys 1 4" VGA Color Monitor ■ Max resolution: 720 x 480 • Bandwidth: 30MHz ■Input: DB 15-pin (analog) RE9513 $449.95 Jameco 1 6-bit VGA Card ■ Supports VGA, EGA, CGA, MDA and Hercules modes ■ Comes with 256KB video RAM upgradable to 512KB (eighl 41464-80) • Capable of 640 x 480 with 256 colors, 800 x 600 with 16 colors VG2000 $149.95 Integrated Circuits Part No. 1-9 iQt Part No. 1-9 10+ 7400 $.29 $.19 7472 $.59 $.49 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 7408 .35 .25 7486 .45 .35 7410 .29 .19 7489 2.95 2.75 7411 .35 35 7490 .49 .39 7414 .35 35 7493 .45 .35 7417 .35 .25 74116 1.19 1.09 7420 .29 .19 74121 .39 .29 7427 .35 35 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 .69 .79 74193 .79 .69 7447 .89 .79 74194 .79 .69 Miscellaneous Components Potentiometers Values available (insert ohms into space marked "XX"): 500Q, 1K, 5K. 10K, 20K, 50 K, 100K, 1 MEG 43PXX 3 rt Watt.15Tum $.99 63PXX VaWatt, i Turn ,. .$.89 PN2222 PN2907 1N4004 Tra . $.12 12 10 nsisfors And Diode 1N4735 .$.25 2N3904 12 1N751 ....15 C106B1 59 1 2N4401 .„ 1N4146 2N3055 , 1N270 ..$.15 07 . 69 2N2222A,, 25 25 Switches JMT123 SPDT.OnOn (Toggle) $ 1 .25 206-8 SPST. 15-pin (DIP) $1.09 MPC121 SPOT, OjOrf-Oi (Toggle) $1.19 MSI 02 SPST, Momentary (Push-Sutton) $.39 D-Sub Connectors and Hoods DB25P Maie.25-pin $.65|DB25H Hood $.39 DB25S Female, 25-pin. ..$.75 1 LCDs XC209R 11 , (Red) S.14 XC556R T1 3 M, (Red) ...$.1 2 XC556G H 3 /<. (Green) „ .16 ! XC556Y T1 3 rt, (Yellow) ■■ .16 4164-100 4164-120 4164-150 41256-60 41256-80 Dynamic RAMs 100ns. WKxl $1.95 120ns,64Kn1 1.89 ISOns.WKxi 1.75 sons, 256K 1 1 3.25 tons, 256K « 1 2.75 41256-100 1Mns,256Kj1 41256-120 120ns, ZKKsl 41256-150 1Mns,2MKx1 511000P-80 8Cns MB i ' SHOOOP-IOiMns.iMBii $2,29 2.19 1.99 8.95 8.49 ■ Call for a complete listing ot IC'S Low Profile 8LP $.11 14LP .....12 16LP 13 24LP 19 28LP .22 40LP... ....26 IC Sockets Wire Wrap (Gold) Level #2 8WW $.49 14WW 69 16WW .79 24WW 1.15 28WW 1.39 40WW..... 1.89 Soldertail Standard A Header Plug Sockets Also Available 24 Hour Order Hotline (415)592-8097 FAX: (415) 592-2503 (415)595-2664 1355 Shoreway Road Belmont, CA 94002 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 tor the latest Jameco catalog! $50.00 Minimum Order Data Sheets - 50$ each For a FREE 90-Page catalog send S2.QD to cover first Class Postage and Handling ■S 1 951 Jameco Electronics fi/91 CA Reside nis Add 6.00%. 6.50% or 7.00% Sales Tax Shipping, handling and insurance are additional. iCosis may vary according to weight and shipping method) Terms: Prices subjecl to change without notice. Items subject to availability and prior sale. Compile im of (ernisAvafianiM is available upon raqutsi. IBM n ■ r«gi!«r#d 1r*dt«iinrfc ol Inumjbanai BuiinHi UjefrfvK f^iessi Plsase reler to Mail Key 2 when ordering G U \jsS~*ix • Customer Service •Technical Assistance • Credit Department • Ail Other Inquiries • (415)592-8097 CIRCLE 114 ON FREE INFORMATION CARD 7AM-4PMP.S.T. AMAZING SCIENTIFIC & ELECTRONIC PRODUCTS LASERS AND SCIENTIFIC DEVICES VRL2K 3mw Vis FtEd Laser Diode SjSlem Kit S159.5D LLIS1K Laser Beam "Bounerr LiilflnarKrl $131. M LHC2K Visible Simulated 3 Color Laser Kit S I ■: W LC7 40 Wall BlirniflO Culling Laser flam SZD.OO RUB« Hi Powered Pulsed Drilling Laser Plans SJrj.orJ LGU10 1 lo 2mw HaNe Vis Red Laser Gun Assembled 5199.00 LLS1 Laser Lite Show - 3 Methods Plans S2D.00 SDSK See in the Dart Mil SZ99.50 EMI IK Electro magnetic Coil Gun Kit {09.50 MCP1 Hi tfelocitr Coll Gun Plan Si5.uo LEV1 Lesllaling Device Plana S1D.00 EH1 Election Ic Hyp.noli.im Tathniques Plan tn.ua HIGH VOLTAGE AND PLASMA DISPLAY DEVICES HVM7K 75.000 Volt DC Variable Output Lab Source Kit $149.50 IOE3K Ian Ray Gun KH. projecl energy without wires .....SO9.50 NIG9K 1ZV/115 VAC Hi Dul Meg Ion Generator Kit SS4.50 EMA1K Teiekinetic Enhancer/Elecltic Man Assembled.. ....S99.50 LG5K Lightning Display Globe Kit 554.50 ESTC1K Worlds Smallest Tell a Coll Kit S49.50 BTC3K Z50KVTableTopTBJla Coll Kit SZ49.50 BTC5 1.5 Million VnllsTesIa Coil Plans $20.00 JL3 Jacobs Ladder- 3 Models Plans $15, DO. GHA1 Anti Gravity Generator Plans $10. OS PFSZD Plasma Fire Saber Assembled $69.50 OPLZO Dancing Plasma In Music and Sounds Assembled. .....$79.50 SECURITY AND PROTECTION DEVICES ITM10 100,000 Uoilhlimidatorop to 20' Assembled S1Z9.5D IPG70 Invisible Pain Field Blast Wave Gen Assembled $74.50 P5P4K Phisor Sonic Blast Wave Pistol Kit $59.50 LIST10 Inlinily Xmtr, Listen in Via Phrnie Assembled $199.50 TAT3D Automatic Tel Recording Device Assembled $24.50 VWPM7K 3 Ml. FMAulo Tel Transmitter Kit 549.50 FMVIK 3 Ml. FM Voice Transmitter Kit $39.50 HOD1 K Homing/Tracking Deeper Transmitter Kit $49.50 EAST nnoERIHG PROCEDURE TOIL FREE 1.1011-221 ITS! er 24 HRS ON 1 603 073-4730 or FAX IT TD 1 -eo3 D7T 5401 VISA. MC, CHECK MO IN US FUNDS. INCLLtQE 1G : , SKIPPITtG ORDERS S100.00 S UP ONLY ADD S10.QO. CATALOG Sim OR FREE WITH OBOEH INFORMATION UNLIMITED P.O. BOX 716, DEPT. R3, AMHERST, NH 03031 CO O z o rr H o Q < LT 94 THE ELECTRONIC GOLDMINE has ore d he l„__ kits cjasiatie in lhc»orlo> ■ftvEft^* 00 I Wte to* Mr 130 1 DIFFERED \ unittue. tafoain l«OJWffi G pitas), anporafe ItSSflff'tOUIt in our ciaiotf l^iqpffl_ e. ULTRAVIOLET SENSOR SUN EXPOSURE METER Smsl Eleargnlc osfix tEsts \fif Energy Iran Die sun and s&jrtis a sicfef vtvt $*M fed tmugri txjx&mt HlH 2 dials fef si&i type iantf stm sow raing (SPF). LJsa C ciiajMry and SfSffial UV umy ASSSTltfed and nadv lo ust irij new suipiui iieni is no* nMAi s a traction of inc atftjjira! est PKiirJTS 9J baflEry. not induded.) G934 $6.95 ■JKV TFUGCEH COIL Ihe win any stock Tube c-ia needs a ■ ug ft\ '.;■/■:■ ^ N1700 $1.Z5 £A. 1O0 fa- $ffi.00 INVERTER TRANSFORMER Smafl 4 ted iTcsrisfoi™ kc* use irtJi H5 C tii carrart l,M)ClD2aCeVtvA3bc/ lloonsaert lutes wth sdieratic. N1703 $2.00 EA 1.000 Ja 11,500 SMA1X BOARD ASSOfOMIJiT Various stroll ertuTLttfids. win nicslvs, capaciiois, Cj tit food assortment ri 4 dWereri 'as is* (Bans. GS83 SZ.OG MOUSE HEADS iMs 5s ihe read tfapncsiffi mcuss wfii a 2 l-pktk. Ccrtiiis trree s**nt-3.2 orxof t-codffs, an C, e^cG&Sfs, lEctora. a Ujtjj mdai ball and omer miscdcneoix pans. Thee « new bu( t94 teen cU off Irom Ov cortrot ta and arc rear* far expefifn*na:cri Said 'as a". 5*is Treat G89i $2,00 BF&032 UTUHJM BATTERY Lonoj \h WiP\ bafcff rrode by Pjftiwnic tedures 10 jeaf sfisff Pit and mouftno as PertecHor re* ccrrsiriiion or rtpSacemcit. G901 49CEA 20 fcf $7^0 minimum order: si 00 (*s *3» srappng ard runoanrj Wei accept MC. Visa and Money Ordera SEND ORDERS TO: The Eledmnic GtHEImino P O B» 5408 SoUBBaW, KZ 85261 PHONE ORDERS (602) 451-7454 FAX ORDERS (602] 151-9195 CIRCLE 178 ON FREE INFORMATION CARD ADVERTISING INDEX RADIO-ELECTRONICS does not assume any responsibility for errors that may appear In the index below. Free Information Number Page 108 AMC Sales 73 75 Ace Products 17 107 All Electronics 90 — Amazing Concepts 94 67 Banner Technical Books 16 109 C&SSales 13 — C1E 11,23 — Cable Ready Company 85 190 Cable Warehouse 12 SO Caig Laboratories 25 182 Chenesko Products 17 — Command Productions 73 176 Communications Specialists 75 55 Contact East 17 58 Cook's Institute 27 191 D&D Electronics 15 127 Deco Industries 17 177 EasyTech 91 178 Electronic Goldmine 94 — Electronics Book Club 18, 7 — Electronics Engineers B.C 18 121 Fluke Manufacturing CV2 189 General Technics 17 — Global Cable Network 83 184 Global Specialties 3 — Grantham College 69 86 Heathkit 67 — 1SCET 82 114 Jameco 92,93 104 Jan Crystals 16 192 Kelvin 71 — King Wholesale 84 53 MD Electronics 85 93 Mark V, Electronics 89 61 Microprocessors Unltd SI — NR1 Schools 76 71 NTE Electronics CV3 185 Optoelectronics 5 56 Parts Express 87 — Perfect Cable 86 101 Pomona Electronics 29 181 Probemaster 25 78 Radio Shack 30 186 SCO Electronics 12 188 Sencore CV4 — Star Circuits 27 — TECI 75 — The SPEC -COM Journal 82 183 Unicorn , 88 187 U.S. Cable.. 12 193 Viejo Publications 29 179 WPT Publications 75 — Wholesale Cable 89 180 Xandi Electronics 17 ADVERTISING SALES OFFICE Gemsback Publications, Inc. 500-B Bi-County Blvd. Farm in gd a Is, NY 11735 1(516) 293-3000 Larry Sleekier, President Christina Estrada assistant to the President For Advertising ONLY 516-293-3000 Fax 1-516-293-3115 Larry Stack ler publisher Af line Fishman advertising director Denise Haven advertising assistant Kelly McQuade credit manager Subscriber Customer Service 1-800-288-0652 Order Entry for New Subscribers 1-800-999-7139 7:00 AM - 6:00 PM M-F MST SALES OFFICES EAST/SOUTHEAST Stanley Lev its n. Eastern Sales Manager Radio- Electro n ics 259-23 57th Avenue Little Neck, MY 11362 1-718-428-6037, 1-516-293-3000 Fax 1-716-225-8594 MIDWEST/Texas/Arkansas/Okla. Ralph Bergen, Midwest Sales Manager Radio-Electronics 540 Frontage Road — Suite 204 Northfield, IL 60093 1-708-446-1444 Fax 1-708-446-8451 PACIFIC CO AST/Mountain States Marvin Green, Pacific Sates Manager Rad io-Electronics 5430 Van Nuys Blvd. Suite 316 VanNuys. CA91401 1-818-986-2001 Fax 1-618-986-2009 RE Shopper Joe Shore, National Representative P.O. Box 169 Idyllwild, CA 92349 1-714-659-9743 Fax 1-714-659-2469 NTE specializes in "replacetivityr the science of getting things up and running again-fast! After all, downtime is costly, so no one can wait weeks on end for an OEM part to come in. With NTE, no one has to! One call gives you access to 3,550 top of the line universal replacement semiconductors that are cross-referenced to more than 240,000 original devices! Included in the NTE line are: bipolar transistors, integrated circuits, rectifiers, diodes, thyristors, optoelectronic devices, varistors, resistors, capacitors, and much, much more All are backed by NTE's exclusive two-year warranty. For your copy of the NTE Technical Guide contact your local NTE distributor, or simply fill in the coupon below and send it to us today with a check or money order for $3.25 each. Please rush me . . copies of the NTE Technical Guide and Cross Reference I manual at $3.25 each. 1 have enclosed my check or money order for a total of $ Name . Company . Address _ City. State Zip Mail to; NTE, 44 T Farond St., Bloomfield, NJ D7Q03 For the name of your nearest NTE distributor, call NTE: Toll Free: 1-800-631-1250 (incl. Canada) Tel: (201) 748-5089 ■ FAX: (201) 748-6224 CIRCLE 71 ON FREE INFORMATION CARD Isolate These And Other Major Components MllTVsAndVCRs- Guaranteed Or Your Money Back VA62A Universal Video Analyzer Plus, Cut Your Video Troubleshooting Time By 54%* With The Patented VA62A Universal Video Analyzer! Identify tuner problems with the only integrated all- channel, VHF, UHF, and cable RF generator. Standard TV, standard cable (2-99), and exclusive programmable cable channels eliminate the question "Is it the TV or is it the cable?" Pinpoint IF troubles with modulated troubleshooting signals and exclusive programmable IF generator. How do you pres- ently identify if the suspected defect is in the AGC, IF/Detector IC, or caused by the tuner? Wouldn't you like to know exactly where the defect is before you order the part or pull the tuner. With the VA62A yon will! Exclusive video patterns completely performance test TVs, VCRs, and monitors — without removing the cover. Is there a picture, is it locked in, is the bandwidth correct, is the brightness and contrast correct, and is the color tint and saturation correct? You'll know in less than 60 seconds using the VA62A's exclusive video patterns. Find defective stages, without disconnecting parts, with exclusive phase-locked drive signals. "Swamp out" the suspect signal and replace it with a known-good signal. You'll isolate the problem to a bad stage in minutes, guaranteed. Test yokes and flybacks with the patented "Ringer". Most shops are forced to substitute yokes and flybacks instead of analyzing circuits. "The VA62A's patented "Ringer" and exclusive flyback drive tests allow you to completely analyze all yokes, flybacks, and IHVTs before you order a new one. Measure signal levels with a fully autoranged FPV and DCV digital meter. The VA62A's built-in meter shows when you are driving into a shorted circuit and prevents you from overdriving criti- cal stages. Plus, measure bias voltages and signal levels throughout the entire TV and VCR. It's obsolete proof: update for new technology with exclusive phase- locked accessories. We'll provide new companion units as the manu- facturers announce new formats, test patterns, etc. This makes your VA62A a protected investment. * Based on a nationwide survey of users who reported an average lime savings of 54% compared to their previous test equipment. For More Details Call 1-8G0-SENCORE ext. 612 (736-2673) CIRCLE 188 ON FREE INFORMATION CARD