(k «783 'ILL "BEASTIE CABLES" IMPROVE YOUR AUDIO? T // / / /^ EBRUARY 1991 TECHNOLOGY - VIDEO - STEREO - COMPUTERS - SERVIC TURI EN YOUR PC INTO A UNIVERSAL FREQUENCY COUNTER Build this plug-in card for your lab computer BUII ILD A NEGATIVE-ION GENERATOR Experiment with high-voltage electronics and the effects tiegative ions ILD A SWEEP/MARKER GENERATOR Test your audio amplifier and filter circuits HOT TROUBLESHOOTING TIPS How to use the horizontal output transistor pulse to diagnose TV troubles ELECTRONICS STANDARDS A refresher course looks at the basis of our measurements OEI-Couolcr ■ in ';<-m..i.iM. Stopped 1 »r(|(jrrny .' ■ MJ - J J 1 1 1 1 Mlt Qftiln I'.il'.r Wi-illli iti :; r i ' mi ii :,, ■ 5*»n 1 :{|iiij|fo 1 [ Step | - 1 i © 4 GEflNSBACK $2.95 U.S. S3.75 CAN xxxxxxxx CAR-RT SORT rx CRD3 ?5n456HRR5165MQ93 02 40 SEP 91 RE FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT PHILIPS Two displays. One great meter. Dual displays provide two accurate measurements. Combined with 16 different measurement capabilities. The Fluke 45 is making people take a second look. The Fluke 45 has the specs to get the job done right. 0.02% basic dc voltage accuracy and 100,000 count resolution on both displays. Basic dc current accuracy is 0,05%, making the 45 ideal for servicing 4-20 mA current loops. The Fluke 45 mea- sures true-rms voltage and current, including ac+dc. Closed-case calibration simplifies the calibration process and increases uptime. Twice as much information. The 5-digit, 100,000 count dual displays give you more information in less time— and with less effort. For example, measure the VDC output of a power supply while measur- ing the VAC ripple. Or check the amplitude and frequency of an AC signal. From a single test connection! More measurement combinations. With the Fluke 45 complex measurements become simple, with standard features like a 1 MHz frequency counter, Min Max, limits testing (Hi/Lo/Pass), Touch Hold® and Relative modes. There are 21 different ref- erence impedances for dB measurements; in the 2H to 16fi ranges, audio power can be automatically displayed in watts. The variety of electrical parameters, measurement functions and display combinations is incredible. Even an RS-232 interface is standard. Connecting the Fluke 45 to PCs, RS-232 printers and modems is as easy as attaching the cable. An IEEE-488.2 interface and internal, rechargeable lead-acid batteries are available as options. Get a great value. Contact your local distributor today for com- plete information on the new Fluke 45. Or call toll -free 1-800 -44 -FLUKE, ext 33. FLUKE 45 DUAL DISPLAY MULTIMETER seas- Dual Display True-mis voltage and cur- rent, includi ng ac+dc 0.02% basic dc voltage dB, Kith 21 reference impedances, a nd and i o power calcu lations Compare and Relative functions Min Max and Touch Hold* functions accuracy 0.05% basic dc cunen! Optional PC software for RS-232 applications accuracy 1 MHz frequency counter Optional IEEE-488.2 interface, battery pack RS-232 interface slandard One year warranty 'SllMBlHd U.S. List PTict John Fluke Mlg. Co., Inc. P.O. Box 9090 M/S 250C Everett. WA 98206 (J .5.: 206-356-5400 Canada: 416-690-7600 Other Countries: 206-356-5500 © Copyright 1989, 1990 John Fluke Mlg, Co.. Inc. All rights reserved. Ad no. 00015. 16 M PC is a registered trademark ol International Business Machines Corporation. FROM THE WORLD LEADER IN DIGITAL MULTIMETERS CIRCLE 121 ON FREE INFORMATION CARD February 1991 bea Bctrontcs 37 TURN YOUR PC INTO A UNIVERSAL FREQUENCY COUNTER Build a f requency-counter/ti me r board that works with Windows. Joe Grasty and Bill Schulz 43 AUDIO SWEEP/MARKER GENERATOR Determine the frequency response of your amplifier or filter design, John Wannamaker 55 NEGATIVE ION GENERATOR Experiment with high-voltage electronics and the effects of negative ions. Anthony J. Caristi 50 WILL "BEASTIE" SPEAKER CABLES IMPROVE YOUR AUDIO? Find out if expensive speaker cables are really worth the money. Richard A. Honeycutt 61 HOT TROUBLESHOOTING TIPS A look at the horizontal output transistor and how to use it to speed yourtroubleshooting. Brian Phelps 63 1 VOLT + = ? A refresher course on standard electric quantities. Dale Nassar ■ 'I^JM'H' Vol. 62 No. 2 6 VIDEO NEWS What's new in this fast- changing field. David Lachenbruch 20 EQUIPMENT REPORTS Data Controls Analyst 2. 71 HARDWARE HACKER Inexpensive visible lasers, and more. Don Lancaster 81 COMPUTER CONNECTIONS Windows pains (and pleasures). Jeff Holtzman AUDIO UPDATE The Boston sound: Part II. Larry Klein PAGE 43 =™~§ SscSfsS IsiSsIs PAGE 50 96 Advertising and Sales Offices 96 Advertising Index 12 Ask R-E 17 Letters 87 Market Center 31 New Lit 22 New Products 4 What's News m □a 33 C > to ID ^TTT77 PC's have become an essential part of any electronics test bench. Until recently, however, PC-based instrumentation was considered to be little more than toys with their limited use and features. That's not true any longer. Take, for example, our PC10 frequency counter. It's a card that fits in an expansion slot in your PC and operates in a Windows environment. It can perform direct counts over 200 MHz, it has a 10- digit display, and a 2.4-GHz range. Because it operates in a computer, additional features such as data log- ging are available. Turn to page 37 for details. en c> .r" o rt h- o in i UJ O n < u. 2 THE MARCH ISSUE GOES ON SALE FEBRUARY 1. BUILD R-E's VIDEO TELEPHONE Transmit and receive high-resolution images over standard phone lines! BUILD A REMOTE CONTROL ANALYZER Examine the output of your IR remote control with this handy device. MICROWAVES: PART 4 An in-depth look at solid-state microwave devices. SEMICONDUCTOR MEMORIES Take a look at the advantages and disadvantages of CMOS, TTL, and EEPROM's. As a service to readers, RADIO-ELECTRONICS publishes available plans or information relating to newsworthy products, techniques and scientific and technological developments. Because of possible variances in the quality and condition of materials and workmanship used by readers, RADIO -ELECTRONICS disclaims any responsibility for the safe and proper functioning of reader-built projects based upon or from plans or information published in this magazine. Since some of the equipment and circuitry described in RADIO-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) February 1991 Published monthly by Gems back Publications, Inc., 500-B Bi -County Boulevard, Famiingdale. NV 1 1735 Second-Class Postage paid at Parmingdale. NY and additional mailing offices- Second-Class mail registration No. 9242 authorized at Toronto, Canada. One*year subscription rate U.S.A. and possessions $17.97, Canada $23 .97, all other countries $26.97, AH subscription orders payable in U.SA funds only, via international postal money order or check drawn on a U.S.A. bank. Single copies S2. 95. c 1991 by Gernsback Publications, Inc. All rights reserved. Printed in U,S.A r POSTMASTER: Please send address changes to RADIO-ELECTRONICS, Subscription Dept., Box 55115, Boulder. CO 80321-5115. A stamped self -ad dressed envelope must accompany all submitted manuscripts andy'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. tllectnmics Hugo Gernsback 0884-1987) founder Larry Stockier, EHF. CFT, editor-in-chief and publisher EDITORIAL DEPARTMENT Brian C. Fen ton. editor Marc Splwak, associate editor Daniel Goodman, technical editor Kim Dunteavy, assistant technical editor Tori Scaduto, assistant editor Jeffrey K. Holtzman computer editor Robert Grossblatt, circuits editor Larry Klein, audio editor David Lachenbruch contributing editor Don Lancaster contributing editor Richard D. Fitch contributing editor Kathy Terenzi. 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. Tucker advertising production Marcella Amoroso producti on as sistant CIRCULATION DEPARTMENT Jacqueline P. Cheeseboro circulation director Wendy Alanko circulation analyst Theresa Lombard o 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 96. Radio-EEectronics Executive and Administrative Offices 1-516-293-3000. Subscriber Customer Service: 1-BO0 288 0652. Order Entry lor New Subscribers: 1 800-999-7139. ^ Trie Audit Bureau of Circulation 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 Silk-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 .$49.00 901 Parts Pkg 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 all 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, VISA MC N. Attleboro, Ma. 02761 m CD X c > ■< ID to CIRCLE 1M ON FREE INFORMATION CARD MJIiUWUm- A review of the latest happenings in electronics. Telephone-Booth Replacement? Advanced Cordless Technologies (Montville, NJ) began public testing of its CT-2 technology in New York City last fall. Based on two pieces of equipment — a pocket-sized portable phone and a "telepoint," low- powered radio transmitter — the tech- nology offers an alternative to public telephone booths. The cordless phones use very little power, getting 20 hours or more from the rechargeable or disposable bat- teries, and are more private and less expensive than cellular phones. The CT-2 phones must be used within 100 yards of a telepoint. Each telepoint, which is about the size of the Manhattan phone book, connects callers to the land-line tele- phone network. From there, calls are forwarded to any location worldwide, and are recorded for billing purposes. A SCALE MODEL SECTION of the super- conducting super collider (SSC), the world's largest and most powerful particle accelerator that is planned for operation in Texas in 1998, is examined by ex- ecutives from Westinghouse Electric Cor- poration. Westinghouse is competing for the contract to manufacture and test more than 8000 16.5-ton superconducting mag- nets that will guide thin beams of protons around the SSC's 54-mile underground tunnel at close to the speed of light. The corporation, a leader in producing super- conducting magnets, developed the niobium-titanium alloy wire that will be used in the magnets. Pictured from left to right are Bruce Boswell, general manager of the collider dipole magnet division; Chairman and Chief Executive Officer Paul Lego; and Dr. John Hulm, chief scien- tist emeritus and director of supercon- ductivity technology. An experimental license granted by the FCC provides two channels, one of them for transmitting calls from handsets and the other for paging the handsets, allowing two-way commu- nications. Approximately 150 test telepoints are planned for public areas in Man- hattan. Each telepoint is capable of handling up to eight calls simulta- neously, reducing the usual wait for public phones. In addition, 50 private branch exchanges will be placed in offices participating in the trial, where the CT-2 will function as a cordless extension phone. The private tele- points will be equipped with adapters that automatically transmit calls to each extension on the exchange, so that, with paging, workers will be able to be reached anywhere in the build- ing. Advanced Cordless Technologies hopes the CT-2 system eventually will change the way public phone calls are made, eliminating the need for coins, and reducing the long waits and inci- dence of damaged equipment that plague phone booths in urban areas. The trial was the first step in the com- pany's long-term plan to offer the CT-2 telepoint service on a national scale. Long-life power source A patented power-source tech- nology developed by the E.F. Johnson Company, a division of Di- versified Energies, Inc. (Minneapolis. MN), couples a unique light-emitting polymer with solar-type cells to gen- erate continuous, low- power elec- trical energy for more than 25 years. Because the power is not generated by a chemical process, it is not adver- sely affected by extremely cold tem- peratures. It has been successfully tested at temperatures ranging from -196°C Cthe temperature of liquid nitrogen) to +100 D C (the boiling point of water). Electricity is generated when a photovoltaic cell is optically coupled to a light-emitting polymer. The light, generated when a phosphor mole- FIG. 1— E.F. JOHNSON COMPANY'S long- life, low-power electrical-energy source is created by combining a light-emitting polymer material (1) and a photovoltaic cell (2, 3) that has a light-collecting sur- face and a pair of electrical contacts {4, 5). When the polymer and the photovoltaic cell are coupled, an open-circuit voltage is generated between the two electrical con- tacts. cule is closely coupled to a hydrogen isotope CH-3 or tritium) within the polymer. Tritium is a radioactive mate- rial that is currently used in a gaseous form as the basis of light sources in watches and exit lights in theaters, and that will require licensing by the Nuclear Regulatory Commission. In the new power source, the tritium is chemically bound into a solid plastic matrix. E.F Johnson has achieved power outputs in the microwatt range — enough to power a pocket calculator or watch, or to charge a capacitor that would supply periodic surge re- quirements and then recharge — and expects to significantly increase the power output. While no end products have been created, and commercial usage is several years away, potential future applications for the long-life, low-temperature power source could he in medical implants, space, com- puters, and superconductivity. R-E A Shocking Offer! Now for the first time in CIE's 56 year history you do not have to be enrolled at CIE to receive our introduc tory Electronic and Electricity Lesson Modules. Available for a limited time to non-students for the shockingly low price of only $99.50. With CIE's patented AUTO-PROGRAMMED method of learning you'll quickly learn and then master the basics of electronics and electricity and then move on to... DC/AC circuit theories, fundamentals of bi-polar junction transistors (BJT), field effect transistors (FET), wiring, diagram and sche- matic readings, component identification, soldering techniques... and much, -much, more. Your commitment to CIE ends with your payment, but CIE's commitment to your success just begins when you receive your 39 lessons, exams, binders and equipment. This special introductory price includes all the benefits and assistance CIE normally extends to its students and graduates. You'll be entitled to unlimited access to CIE's faculty and staff to assist you in your studies via a toll free 800 number six days a week, 24-hour turnaround on grading your submitted exams, CIE Bookstore privileges, a patented learning method, reference library, a student, faculty and alumni electronic bulletin board and a free issue of CIE's school newspaper The Electron. All this knowledge and support will put you on the road to understanding digital electronics, microprocessing principles, computer systems, telecom- munications, and much, much, more. • Free Issue of The Electron • Build your personal burglar alarm • Instructors available 6 days a week • 20 lesson books containing 39 theory and hands-on training lessons and exams. ' Bookstore Privileges • Patented Learning Method • Electronic Bulletin Board • 24-Hour Grading □ Yes, send me CIE's 39 Introductory Electronic and Electricity Lessons and Equipment. Name: Address: City: .Apt. #: State: . Age:_ .Zip: Phone ( .) BOOKSTORE 1776 Easi 1 .tii Street Clevrlomf, Ohio HI 14 (216)78I.«W Total Merchandise: Ohio Residents add 7% Sales Tax: California Residents add 6-1/2% Sales Tax: Total this order: $99.50 Method of Payment: Amount Enclosed . . . % 3 Personal Check or Money Order □ Master Card □ Visa □□□□□□□□□□□□□□CD Card Expiration Date: Signature CHARGE BY PHONE! 9 AM to 4:30 PM Eastern Time; from Ohio 1-800-523-9109 from all other states 1-800-321-2155 Tl m ra c > < VIDEO NEWS What's new in the fast-changing video industry. DAVID LACHENBRUCH • European HDTV setback. Europe's plan for an orderly transition to HDTV suffered a severe blow with the announcement that two British direct-satellite broadcasters planned to merge. Sky Channel has been broadcasting in standard PAL, while British Satellite Broadcasting was beaming a signal in the expanded- definition MAC (multiple analog com- ponent) system, which separates the chrominance and luminance signals to provide a better picture. Under the merger agreement, the combined satellite system will transmit in PAL only, after a transitional period. BSB*s MAC transmissions were part of a plan to create a new stan- dard for direct-satellite transmission, which would eventually lead to a "compatible" HDTV system — com- patible with MAC transmissions, that is. MAC and PAL are incompatible. MAC has already lost favor in Ger- many, where broadcasters are using Luxembourg's Astra satellite and transmitting in PAL. At this time, only France is still committed to MAC. Un- der the European Eureka project, the new all-European HDTV service, HD- MAC, was to be phased in about 1992. Now everything is up in the air, so to speak. • Japan's HDTV receivers. While the European HDTV system was to have some measure of com- patibility (even if only to MAC trans- missions), Japan's Hi-Vision HDTV is compatible with nothing, and will re- quire all-new TV sets, VCR's, vid- eodisc players, and so forth. Hi- Vision is being broadcast by NHK, the government-chartered broad- caster, by satellites. Japanese TV set makers have now introduced the first consumer model Hi-Vision receivers, priced generally in the $17,000-$35,000 range, promising prices could be cut in half in about a year. Newspaper and magazine reports bemoan how far "behind" the United States is as compared to Europe and Japan in instituting HDTV broadcast- ing, but they neglect to mention that the American project is far more am- bitious than the others. The U.S. plans to integrate HDTV broadcast- ing with conventional transmissions, broadcasting from terrestrial TV sta- tions rather than instituting a com- pletely new incompatible satellite- transmitted service. Official testing of proposed American HDTV sys- tems is scheduled to start in March. • Multimedia. That's one of to- day's magic words, and no one knows how it's going to affect the future of television, video, or comput- ing. At least three systems designed to combine video motion, audio, and interactivity are scheduled for major introductions this year. CDTV, which stands for "Commodore Dynamic Total Vision," is scheduled for intro- duction early this year, as an exten- sion of the Amiga computer system in an attachment for TV sets, with such programs as encyclopedias, cookbooks, atlases, and sophisti- cated video games. The hardware is scheduled to cost less than $1 ,000 to start, with CD-ROM programs at $25 to $100 each. CDTV has half- screen full-motion or full-screen half- motion (15 frames per second). The competing CD-I (Compact Disc Inter- active), backed by Philips and Sony, will debut in the second half of this year, probably without full motion, but a full-motion adapter will be added later. Meanwhile. Intel introduced a two- chip set to bring its Digital Video In- teractive (DVD system to personal computers at a premium of less than $1 .000 at the start. The DVI chips permit interaction with full-motion video, as well as storage of digital video on PC's. Thus it seems that the TV set moves closer to the computer, and the computer closer to the TV set. * Digital VHS sound. You can't buy it now, but perhaps in a few months there will be another feature for VHS video recorders. At the re- cent Japan Audio Fair, both JVC and Hitachi demonstrated VCR's with digital audio, and Matsushita (Pan- asonic) has a similar system. The new digital sound is for Super VHS re- corders, whose expanded video bandwidth provides enough addi- tional space for its 16-bit PCM sys- tem. The 8mm format already has PCM audio with an 8-bit system. The VHS group is reluctant to commer- cialize digital audio because of the dispute over digital-audio recorders and copyright protection, but there is anticipation that it will be offered starting this spring. The PCM audio system, standardized for S-VHS re- corders, uses a 48-kHz sampling fre- quency, and depth-multiplex record- ing to place the video and audio signals on different layers of the tape's magnetic coating. The two other soundtracks (linear and helical FM) of the VHS recording standard will be unchanged to maintain com- patibility. R-E COMMODORE'S CDTV Interactive graphics player Is expected to cost less than $1000. 6 PARTS HOTLINE Your nearby Radio Shack store has a huge selection of popular electronic components. Plus, we can special-order 10,000 items from our warehouse— ICs, tubes, semiconductors, phono car- tridges and styli, even SAMS 1 manuals. Service is fast and there's no minimum order or postage charge. BATTERY HOTLINE In addition to our large in-store stock, Radio Shack can now supply almost any currenlly manufactured consumer-lype battery — for cordless phones, computer memory, camcorders, transceivers, pagers and more. No postage charge! 1991 Semiconductor Reference Guide. A "must" for electronics build- ing and repair. This new edition gives you a 95,000-item semiconductor sub- stitution guide plus detailed data on Radio Shack ICs. SCRs. LEDs, diodes, transistors and optoelectronics, #276-4014 3.99 Bench /Portable LCD Digitat VOM, Our best multitester! Displays transis- tor gain directly and has diode -check, memory and continuity functions. Agtoranging or manual modes. Mea- sures to 1000VDC, 750VAC, 10 amps AC/DC and resistance. #22-195 99.95 4-in-1 Soldering Tool. Operates any- where on standard butane lighter fuel. Refills in seconds. #64-2161 29.95 ft) 1.0 mm Tip. #64-2163 9.95 (2) Blow Torch Tip, #64-2168, (3) Heat Blower, #64-2169, (4) Hot Knife, #64-2170 available on special order Each 9.95 h\ Bright Krypton Bayonet-Style Lamps for Flash- lights. Use in place of standard lamps for super brightness. For ex- ample, K4 re- places standard PR4. Each 790 Type volls mA Cat. No. K4 K2 233 2.4 34 480 600 830 272-1169 272-1156 272-1157 K3 K15 K12 K18 36 4.8 6.0 7.2 800 700 650 700 272-1158 272-1162 272-1163 272-1164 (1) <■ Replacement Rod Antennas. For cordless phones, radios, portable stereos, walkie-talkies and your own custom projects, 16 styles in stock! m 30 Vs". #270-1401 2.99 (2) 13". #270-1407 2.79 (3) 235/a". #270-1417 3.49 Battery Holders. Ideal for projects, for replacement or for building exter- nal power packs. Our store near you has 15 different styles in stock! (4) Holder for 8 "AA" Cells. 9V- lype snap connector. #270-407, 1.29 Replacement Fuses. For appliances and vehicles. Over 60 values in stock! (5) 10-Amp Fuse for Microwave Ov- ens, #276-1256 Pkg. of 2/1.29 10-Amp Plug-In DPDT Relays. With 12V0C Coll. #275-218, 5,99 With 125VAC Coil. #275-217, 5.99 Relay Socket. #275-220. 1.79 {1) Mini-Clip Test Leads. 48" long. Mini test clip atone end, banana plug at the other. Includes pin-type plug adapters. #278-1160 Pair/3.99 (2) Test Probes With Coiled 6-Ft. Leads. #278-750 Pair/4.99 (3) Deluxe Soft Carrying Case. Per- fect for multitesters. #22-149 . . . 7.95 Six-Outlet Power Strip With Spike Protector. Noise filter, breaker. Rated 15A. #61-2780 29.95 o Piezo Speaker. Only 1 31/32" -dia. by s/eV thin. This high-efficiency device can be driven by ICs. 500 Hz to 20 kHz. 1200 ohms. #273-091 . . . 2.49 (1) Dual Mike Cable. For balanced hookups. 30 ft. #278-1281 . 19.95 (2) Super-Flex Mike Cable. Extra- supple. 30 ft. #278-1282 14.95 (3) 4-Conductor Double-Shielded Cable. 30 feel. #278-777 7.95 (4) Magnet Wire Assortment. 22, 26. 30 gauge #278-1345 4.99 (1) Precision Thermistor. Range- -50 to +110°C. #271-110 . 1 99 (2) High-Speed 12VDC Motor. Up to 15,200 HPM at no load. About 2" long (with shaft). #273-255 . . . 2.99 (3) 12VDC Brushtess Micro Fan. Ideal for cooling mobile equipment and hum-sensitive Circuits 4 6 CFM 150 mA. #273-244 17,95 Mercury Bulb Switch. Just the thing for experiments and alarms. Con- tacts rated 5 amps at 125 VAC. Style may vary. #275-027 1.29 § §§ I 1 Surface-Mount Resistors. 200- piece assortment! Popular values rated 'to watt, 5%. #271-313. Set 4.99 fSTT5S] Electronic Counter Module. Pre- wired! Great for a traffic or event counter. Counts up to 99,999. Ad- vanced (or reset) by external switch closure or digital circuit. Accepts count rate up to 7 Hz. Has >&" liquid crystal display. Requires "AA" bat- tery. Low current drain— only 4 uA With data. #277-302 16.95 Since 1921 Radio Shack has been the place to obtain up-to-date electronic parts as well as quality tools, test equipment and accessories at low prices. Over 7000 locations to serve you — NOBODY COMPARES Prices apply at participating Radio Shack stares and dealers. Radio Snack is a division ol Tandy Corpoiaiion .Aarffo/hacfc AMERICA'S TECHNOLOGY m w C > < to CIRCLE 78 ON FREE INFORMATION CARD The country honors its technicians with the celebration of National Electronics Technicians Day. IN RECOGNITION OF ITS NEARLY 28,000 members, the Interna- tional Society of Certified Elec- tronics Technicians (ISCET) is lobbying for a joint resolution or Congress to designate March 5, 1991 as National Electronics Technicians Day. Congressmen Martin Frost and Pete Geren (Texas) have whole-heartedly agreed to serve as the original co- sponsors of this bill in the House. Senate approval is also required for this special legislation, and ISCET is seeking an original Sen- ate sponsor for this bill. ISCET's chairman, Leonard Bowdre, hopes that by officially declaring March 5, 1991 as Na- tional Electronics Technicians Day nationwide recognition will be focused on the high standards of performance and excellence maintained by professional tech- nicians. Most people underesti- mate our country's need for highly skilled and specially trained electronics technicians, who play a vital role in the elec- tronics manufacturing, testing, and servicing industry. What is ISCET? As the proud offspring of the National Electronic Association (NEA), ISCET was founded in 1970 by a committee of Certified Electronics Technicians, whose main purpose was to foster re- spect and admiration for their profession. By maintaining rigorous standards in its cer- tification program, ISCET is able to separate the highly skilled and knowledgeable technicians from those with less experience. IS- CET's main functions include di- rection and administration of the GET program, the national ap- prentice and training program, the technical information train- ing and upgrading programs, and the serviceability inspection programs. The GET program was de- signed to measure the degree of theoretical knowledge and tech- nical proficiency of practicing technicians. A technician with a GET certificate is thought of in the industry as one who pos- sesses the training and expertise necessary to perform their job with professional competence. Since its inception in 1965, the CET program has become more widely accepted by technicians, manufacturers, and consumers. Many organizations encourage, and sometimes require, their w o z o oc H o LLI w ISCET AWARDED MISSION SPECIALISTS George D. Nelson and James D. Van Hoften Q titles of Honorary Certified Electronics Technicians for servicing and repairing the Solar § Max satellite. Their 305-mile high 5-day service call cost S45 million, but saved the cost of cc replacing the 5,000 pound, $300 million satellite. technical employees to be cer- tified by ISCET, The CET exam To become certified by ISCET, one must pass both a 75-ques- tion Associate-level CET test, and a 75-question Journeyman-level test. Each multiple-choice exam must be passed with a grade of 75% or better. An electronics technician or student with less than four years of experience may apply for the Associate-level exam, covering the following subjects: • Basic Mathematics • DC Circuits • AC Circuits • Transistors and Semiconduc- tors • Electronic Components • Instruments • Test and Measurements • Troubleshooting and Network Analysis A fully certified technician must also pass one or more of the several Journeyman options available in specialized fields of electronics. A Journeyman cer- tified technician must also have four or more years of education or experience in electronics. The Journeyman options that are available are: • Consumer — Subjects covered include antennas and transmis- sion lines, digital and linear cir- cuits in consumer products, TV and VCR servicing problems and use of test equipment. • Industrial — Subjects include transducers, switches, power factor, differential amps, closed- loop feedback, basic logic cir- cuits and functions, elements of numeric control, thyratrons, and SCR controls. • Communications — This test covers two-way transceiver theo- ry and servicing, receivers, trans- mitters, basic communications theory deviation sensitivity, quieting, and troubleshooting. • FCC Legal — This is a 25-ques- tion optional exam covering FCC regulations. Applicants must take the Associate exam, the Communications option, and the FCC Legal exam to receive a general radio- telephone license. • Computer — This test covers operation of computer systems with basic emphasis on hard- ware. Subjects covered include basic arithmetic and logic opera- tions, computer organization, input and output equipment, and memory and storage. Some knowledge of software and pro- gramming is required, and the ability to explain troubleshooting procedures is required. • Audio — Products covered in this option include turntables, tape decks, compact discs, and radios. The exam consists of both digital and analog sections, amplifiers and sound quality, system set-up, speaker installa- tion, and troubleshooting audio systems. • Medical — The priorities of this option are electrical safety and accuracy of calibration for electromedical instruments. The technician must be familiar with basic vocabulary of medical in- strumentation, telemetry, mea- surements, differential and oper- ational amplifier applications. • Radar — A general knowledge of both pulse radar and continu- ous radar is necessary to take this Journeyman option. The test covers transmitters and re- ceivers. CRT display systems and their power supplies, antennas, transmission lines and their characteristics. • Video — The rapidly growing field of video is covered by this exam. The technician needs to know NTSC standards, video basics, test signals, and the oper- ations of both the electronics and mechanical systems in VCR's. Also covered are 8mm video, cam- corders, cameras and monitors, and the microprocessors used in video products. The fee for the CET exam is $25.00, which includes both the Associate exam and any one Journeyman option, if taken in one sitting. If the Journeyman option is taken separately from the Associate exam, each test is $25.00. Each additional Jour- neyman option is $25.00. If you fail any portion, the first retake is free, after a 60- day waiting period. The fee for any additional retake is $12.50. If you choose to take the FCC Legal exam after you have successfully completed the Communications option, an additional fee of $10.00 is also required. Certified Electronics Intuition Kugi*lc*1i** ^n,. ii ... ~.«J..~ *«c«v IWESP A t. ii hittfan eg r'n.Tt pit.Mia. ihjl ^UrttJKClUir rjluiij^k /^K^-aSff orJi-tf&L LARRY STECKLER, editor-in-chief and publisher of Radio-Electronics magazine, received this CET certificate back in 1975. Don't underestimate the diffi- culty of the CET exam. Every year over 6,000 exams are taken by hopeful technicians, but only 30% of those taken pass — it's not an easy test. The best way to pre- pare for this exam is to study dili- gently. Tab Books. Inc. publishes The CET Study Guide, by Sam Wilson, which will help you pre- pare for both tests. ISCET also has additional study guides available for a nominal fee. If you're interested in taking the CET exam, you can contact any one of ISCET's volunteer test administrators listed in this arti- cle for details. The exams are scheduled to be given the week of March 5, 1991. There are many more test administrators throughout the country than we have provided. Those listed in this article are just the ones who will be giving the exams during the week of March 5. For any ad- ditional information you may need, you can contact ISCET at 2708*West Berry St.. Forth Worth. TX 76109; phone (817) 921-9101. Now that we have all of the for- malities out of the way. let's take a look at how ISCET honored two technicians who have gone above and beyond their call of duty. The world's farthest service call ISCET not only acknowledges those who have successfully com- pleted their certification exam, but those who have exhibited outstanding technical achieve- ment. Such is the case of Mission Specialists George D. Nelson {Phd, Astronomy) and James D. Van Hoften (Phd, Hydraulic Engi- neering) who were awarded the titles of Honorary Certified Elec- tronics Technicians. Figure 1 shows these astronauts being honored by ISCET. The astronauts were recog- nized by the ISCET Board of Gov- ernors for their exemplary perfor- mance in space during the period of April 8-12, 1984, when the So- lar Max satellite was serviced, re- paired, and returned to Earth's orbit. They were cited for the ex- tremely difficult and delicate work required to repair the elec- tronics box for the coronagraph- polarimeter, an instrument that was not designed to be repaired in space. While working outside the space shuttle Challenger, where the 5,000 pound Solar Max was berthed, the astronauts used special power tools designed for weightless conditions to repair electronic instruments. The sat- ellite was restored to operational health for the first time in three years, and added years to its useful lifetime. R-E ISCET VCR Cross Reference, L VCR Model Number Cross Reference and VCR Paris Cross Reference UPDATED - Feb. 1990. 272- page reference guide. $35 pi us $3 shipping. DISC - IBM-compatible disc with expandable data base. $99 plus $1 shipping. COMBO OFFER: Book and disc for only $125 plus $3 ship- ping. MORE INFO? Contact ISCET, 2708 West Berry St. Fort Worth TX 76109 (817) 921-9101 A I tow** ^6 w e e"k T$ el >ve ™wb en usi nu ~e™ onaTcTTec* s"o r VISA ana MasterCard. Money orders end ceshiers checks processed immediately. Amoum VISA t: MasterCard r Adtirau _ City ma Memuer. H ISCET, ~l NESDA Texas resldems multiply dollar .a:je '■ 7 ,V, fr;r laxes Foreign shipments please add Internal I anal postage. Send 10: ISCETT. 270SW. Berry St., Ft. Worth TX 76109 m CD H C > 3J -< ISCET CERTIFIED ADMINISTRATORS FOR THE GET EXAM T. Van Iderstine. CET Art Scrensen. CET Paul K. Tan, CET Bob Belters, CET Joseph Carney III, CET F. Gilbert Smith, CET Southwest State Tech College 1416 N. Lincoln Ave. 915 Augusta St. Washtenaw Comm. College Radio Meier America 822 Creekridge Dr. 925 Dauphin Island Pkwy Loveland. CO 80538 Oak Park, IL 60302-1678 4800 E. Huron River Dr. 6365 Mills Creek Lane Dallas, TX 75218 Mobile, AL 36605 (303) 669-0883 (312)848-6327 Ann Arbor, Ml 48106 N. Ridgeville, OH 44039 (214) 348-7734 (205) 947-4441 John F. Stack house, CET Paul R. Towbridge (3131 973-3316 (216) 871-8900 Est. 241 Frank Sosolik Jr.. CET Jim Gorman ITT Inst, of New Cinema Artists Dr. Joel Goldberg, CET A.C. Falcione, CET T S.T.I. Servicing Depl. Eastern AZ College 2121 South Blackhawk 407 E. 25lh SI.. Slh Floor 6762 Red Cedar Lane Falcon Electronics, Inc. Box 4454 600 Church St. Aurora. CO 80014 Chicago. IL 60616 Union Lake, Ml 48085 3266 Kenl Rd. Waco, TX 76705 Thatcher, AZ 85552 (303) 695-1913 (312) 225-3400 (313) 360-2092 Stow, OH 44224 (817) 799-3611 (602) 428-1133 Anthony R Valdez, CET Frank Teskey, CET E. Eugene Ranla, CET (216) 688-2451 Frank Grabrec, GET 1919 Rolling Hills Rd. F. J. Teskey Enterprises Macomb Comm, College Andrew M. Flock, CET Thomas C. Underwood, CET Dyna-lronics Cortex, CO 81321 3094 Lafayette Rd. 14500 Twelve Mile Rd Hickok Tech. Inst Sony Service Company 1704 E, Claremonl (303) 565-8457 Indianapolis. IN 46222 Warren. Ml 48093 5100 Pearl Rd. 3201 Premier #100 Phoenix. A2 85016 (317) 926-2639 (313) 445-7455 Cleveland, OH 44129-1240 Dallas. TX 75063 (602) 279-4176 John E. DePalma. CET CT School of Electronics Leonard E. Bowdre. CET Walter E. Reilly III, CET (216) 351-4600 (214) 550-5270 H.J, Paine. CET 586 Ella Grasso Blvd. 125 SE Thornton Ave. Lansing Comm. College David J. Garwacki, CET Preslon Wallace. CET 4631 E. Slh SI. New Haven, CT 06519 De Moines, IA 50315 901 Cleveland St. 4846 Oak Glen Dr. 1757 Triple Crown Dr. Tucson, A2 85711 (203) 624-2121 (515) 964-6484 Lansing, Ml 48906-5431 Toledo. OH 43613-3048 Corpus Chrisli, TX 78417 (602) SSI -6784 Dennis P. Abell. CET Gerald P. Breilbaeh. CET (517) 485-g551 (419) 475-9221 (512) 852-8022 Silvino Alonso 3433 Royal Oak Or KDTH Radio Station Willard Rush. CET Robert D Jerig. CET CA Business Inst. Tilusville, FL 32780 8th S Blufl SI. Oakland College 697 Villa Ave Leonard M. Cowherd. CET 3550 Johnson Ave. (305) 269-4208 Dubuque. IA 52001 3361 Aspen-6304 Akron, OH 44310 Peidmonl Tech. Ed. Center El Monle. CA 91731 (319) 588-5694 Lake Orion. Ml 48359 (216) 762-5816 PO Box 999 (818) 444-7779 Edward Guary Jr., CET (313) 391-2152 Culpeper. VA 22701 Eddy's Radio & TV Service Michael L. Baughman. CET J.R. Manchester. CET (703) 825-0476 Howard Bardach. CET 1110 NE 4th Ave KS Cily Area Vo Tech John H. Spuriin. CET University ol Akron The Audio Specialist Ft. Lauderdale. FL 33304 2220 N. 59th St. Wayne County Comm. College i PO Box 61 Studio Cily, CA 91604 (818) 763-3009 (305) 463-2998 James D. Hile. CET Pinellas Vo-Tech Kansas City, KS 66104 (913) 334-1000 Stanley Creitz, CET 8551 Greenfield Akron. OH 44309 Jim Teeters, CET Delroil. Ml 48228 (313) 496-2691 (216) 745-0053 J.S. Glosemeyer, CET 2937 E. Maiden Ave. Norfolk, VA 23518 (804) 428-5772 C.S.E.A. 6100 154lh Ave. N NCK Area Vo Tech David Lewicki, CET East OK Cnty Vo Tech. Tambra Oberlander Clearwater. FL 34620 PO Box 507, West Campus Dr, 9B30-26th Ave. 4701 N. Choctaw Rd. Del Dressel, CET Oakland TV PO Box 110970 13666 S. Hawthorne #3 (813) 531-3531 Beloit, KS 67420 Plymouth. MN 55441 Choctaw. OK 73020 Hawthorne. CA 90250 (213) 679-9186 Karl A. Hunter, CET (913) 738-2279 (612) 627-2778 Exl. 5210 (405) 390-9S91 FL Comm. College Keith E. Knos. CET R.J. Chenoweth. CET Roy W. Yonce Tacoma, WA 98411-0970 John V. Craig, CET 2007 Callin Dr. Knos Electronics Chillicolhe Area Vo Tech Oklahoma Jr. College (206) 840-4975 Oxnard College Jacksonville. FL 32211 1206 Elm Blvd. 1200 Fair SI. PO Box 470992 4000 S. Rose Ave. (904) 744-8480 Liberal, KS 67901 Chillicolhe. MO 64601 Tulsa. OK 74147 Leonard Laabs. CET Oxnard. CA 93033 (316) 624-5908 (816) 646-3414 (918) 663-9500 (805) 986-5807 Perry "Jim" Parks. CETiCA Walla Walla College Nu-Pro Service Edward J. Kimmel. CET James D. Everett. CET Larry Broschart, CET 204 S. College Ave. Anlhony J. Haag 1055 Hwy 434 2061 Eastern Parkway Platte Cnty. Avt. School 14124 NEKnoltSL College Place, WA 99324 PO Box 27264 Winler Spnngs. FL 32708 Louisville. KY 40204 PO Box 1700 Portland. OR 97230 (509) 527-2712 Concord. CA 94527-0264 (305) 699-8811 (502) 451-3457 Plalte City, MO 54079 (503) 255-6713 (415) 6B2-9010 Noel Shevack Test Day Feb. 24th (816) 329-4646 Gene Hedgepelh, CET/CA Cecil C. Poe, CET David Marson. CET Mew England Inst of Tech. Lamarr W. Ritchie. CET James Blanger, CET RD 4-639 E. Alberdeen Rd. 1012 McClain Dr. Golden State School 1126 53rd CI. Hazard State Vo-Tech School Beltronics. Inc. Mountaintop. PA 18707 Sunnyville. WA 98944-1270 3916 S. Chaster Palm Beach, FL 33407 101 Vo-Tech 19 Proctor Hill Rd.. Box 330 (717) 868-6566 (509) 839-3995 Bakersfield, CA 93307 (305) 842-8324 Hazard. KY 41702 Kollis, NH 03049 (805) 833-0123 Daniel B. Mundy. CET (606) 436-3101 (603) 465-2422 L.A. Leibensperger. CET Lincoln Tech. Inst. James C. Shambow, CET Fred Poller. CET Norman's Electronics W.H. Hartzfeldl. CET Carl Meyer. CET 5151 Tilghrnan St. Allentown. PA 18104 ITT Tech. Inst. Ameritech College 3653 Clairmonnt Rd. NE Delta- Ouachita Vo Tech. 11 Hemlock Dr. 12720 Tech. Insl. 6843 Lennox Ave. Allanla, GA 30341 509 Vocational Pkwy, West Seneca, NY 14224 (215)398-5300 12720 Gateway Dr. Suile 100 Van Nuys, CA 91405-4043 (404) 451-5057 W Monroe. LA 71291 (716) 674-7113 Seattle. WA 93168 (8181 901-7311 James Peek, CET (318) 396-7431 Gregory J. Reiber. CET Thomas Plant, CET 29 Dean SI. (206) 244-3300 Kevin J. Price, CET Panasonic Sleven B. Lumpkin. CET Bryanl & Stratlon Pawtucket. Rl 02861 N.E.C. 4245 E. International Blvd. 164 Acadian Dr. 5775 South Bay Rd. (401) 723-3500 Exl. 333 Michael Szymkewicz. CET 825 E. Hospitality In Norcross, GA 30093 Lafayette, LA 70503 Clay, NY 13041 Ofymic College San Bernardino. CA 92408 (404) 717-6858 (318) 233-8942 (315) 452-1105 Donald Haag, CET 16th & Chester !714t 885-3B96 RR 3 Box 92 Bremer Ion, WA 98310 Joe T. Reese. CET Larry Steckler. EHF'CET Walertown, SO 57201 (206) 478-4802 Lynn Reynolds Reese Elect. Inc. Box 499 M.S. McCannJr.. CET Radio Electronics Magazine (605) 886-8932 Woodrulf Region Occup. 129 South Green SI, McCann Electronics 500 B Bi-Counly Blvd Cnlr. 302 W. Weber SwainsborO, GA 30401 100 Division St Farmingdale. NY 11735 William S. Warren, CETVCSM Richard K. Evans. CET Stockton. CA 95203 (912) 237-7010 Metairie. LA 70001 (516) 293-3000 2540 Sutherland Ave. PO Box 217 (209) 944-4612 (504) 837-7272 Knoxville. TN 37919 Wilkenson. W VA 2S6S3 W.R. Rooks. CET Huberl West. CET (615) 546-1121 (304) 752-7267 Frederick J. Smith. CET Shiloh Rd. Rl 6 James R. Sorrels. CET'CSM Adirondack, Comm, College Ed. Dept/CA Mens Colony Box 181 110 Oakridge Dr. Bay Road Joseph H, Hudson Jr., CET PO Box 8101 Amencus, GA 31709 Shreveporl. LA 71106-7113 Glens Falls, NY 12801 1500 Yarborough Dr. David E. Nida San Luis Obispo, CA 93409 (912) 928-0283 (318) 686-4637 (518) 793-4491 Exl S26 Sherman, TX 750g0-5545 National Education Center (8051 772-2009 (214) 892-9356 5514 Big Tylor Rd. James P. Van Sant. CET Gordon L. Burgess, CET Linda Dickinson Cross Lanes. W. VA 25313 Jon Ft. Sturlz, CET Pickens Tech, Great Northern Paper Co. Craven Communily College Rodger W. Minalra (304) 778-6290 Exl. 24 10840 Alandale Way 240 Burnt Ml Rd. E. Millinocket, ME 04430 PO Box 952 Collin County Comm, College Rancho Cordova, CA 95670 Jasper. GA 30143 (207) 769-9912 Ext. 1300 Havelock. NC 28532 2200 W, University (916) 635-6000 (404) 692-3411 (919) 447-5559 McKinney, TX 75070 (214) 548-6830 Duane Busby, CET 2027 Sherman Ave. Donald Surelle. CET William J. Neilsen Earl Tickler, CET Ralph V. Pollmiller. CET Madison. Wl 53704 2728 Panay CI. 404 S. Main Rets Tech. Tram Center Ralphs Electronics J.W. (Dub) Newson, CET (608) 244-0339 Carmichael, CA 95608 Moscow, ID 83843 1520 S. Calon Ave. PO Box 633 1310 19lh St. W3 (916) 487-6959 (208) 882-2123 Baltimore, MD 21227 Jacksonville, NC 28540 Lubbock, TX 79401 o (301) 644-6400 (919) 455-2828 (806) 763-8246 Larry Geissler, CET Indianhead Tech. College Charles Fetters, CET Douglas E. Minler. CET O Mesa State College Amer. College ol Tech, Robert A. Ciulelti Wayne Smith. CET Arthur J. Rupperl, CET 600 N. 21st SI. DC PO Box 2647 102 N Center 444 Fairmont St. 224 St. John SI 30217 St. Andrews Supenor. Wl 54880 tz Grand Junclion, CO 81502 tlj (303) 242-9307 Bloomington, IL 61701 Fitchburg. MA 01420 Arden, NC 28704 Georgetown. TX 78628 (715) 394-6677 Ext. 275 (309) 828-51 61 (508) 674-1000 Ext. 250 (704) 255-7671 (512) 495-1679 uJ Rick Page FA. Schwarzkopl, CET'CA Frank Serra, CET Melvin E. Talbert, CET Charles R Schlieper. CET Jacob Klein. CET O Technical Trades Ins!. Triton College Rm T-201 Serra's TV Video Heifig Meyer Service Co. Temple Jr. College Northcentral Tech College q 2315 E. Pikes Peak Ave 2000 Fiflh Ave. 1686 Mass. Ave. PO Box 64189-2858. Owen Dr. 2600 South First 1000 Campus Ave. < Colorado Springs. CO 80909 River Grove, IL 60171 Cambridge. MA 02138 Fayetteville, NC 28306-0189 Temple, TX 76504 Wausau, Wl 54401 tx (719) 632-7626 (312) 767-4126 (617) 492-2661 (919) 483-0801 (817) 773-9961 Exl. 255 (715) 675-3331 Exl 263 10 SELECT 5 BOOKS for only $ 4^ (values to $127.70) and get a FREE Gift! I93& $64,00 Counts 35 3 3M7P StB.9'5 2£2£P S16.9S 3278 S36 35 Counti II 2 3031 P Si 7.35 1001 B04P 521,95 Count! a* 2 2860P SU.9S For over 25 years, your most complete source for electronics books. 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. • Sonus Books. Starting immediately, you will be eligible for our Bonus Book Plan, with savings of up to 80% off publishers' prices. • Club News Bulletins. 1 5 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 1 2 months and may resign at any time thereafter. * Ironclad No-Risk Guarantee. If not satisfied with your books, return them within 10 days without obligation! * Exceptional Quality. All books are quality publishers' editions especially selected by our Editorial Board. (posters' Prices shrwn) ELBCTROMC tcoRCurrs WITH 1367P S74.SE 2920 529.95 Counts SI 2 3138 $60.00 Counts as 3 337a I2B.9S Counts as 2 FREE when you join 15 Easy Electronic Projects From Delton T. Horn Projects you can build— some unique, some old favorites— from the author's vast treasury of electronics know-how. AIl-Time FJNgrik Electronic Projects 2925P 39.95 3355 (26.95 Counts » 2 3205 S24.9S 3241P 316.95 1M Electrons BqqkCljb sm Xl5' / Blue Hid $ e Summit, PA 17294-0B10 Please accept my membership in the Electronics Book Club and send the 5 volumes listed below, plus my FREE copy of Dstton T. Horn's Atl-Time Favorite Etecttonic Projects |3105P), billing me S4.95 If not satisfied. I may return the books within ten days without obligation and have my membership cancelled. I agree to purchase al feast 3 books at reguEar Club prices during the next 12 months and may resign any time thereafter, A shipping/handling charge and saies lax will bo added to all orders. Name Address City State _ Zip 331? «3,95 !GiaP (17.95 All books are hardcover unless number is followed by a "P" lor paperback. [ Signalure | ValkJ for new members only Foreign applicanls will receive special ordering injunctions Canada must remit . in U.S. Currency. This order subjecl to accEplance by Ihe Electronics Book dub RPIE291 l_ . — — ^ — — — _-____-_ „ _ _ ANTENNA ifl 3270 537-95 Connie as 2 2735-P $16.95 HOWE ELECTRONICS FIX !T BOOK I 2790 P SI 4.95 28B3P 317.95 (Publishers' Prices Shown) 81991 ELECTRONICS BOOK CLUB m C > < 11 ASK RE Write to Ask R-E, Radio-Electronics, 500-B Bi-County Blvd., Farmingdale, NY 11735 'Si O O _ Q Q < APPLE DISK I have an Apple lie and was recently given a hard-disk sys- tem to use with it. I was told that the disk had already been formatted but I haven't been able to get it to work in my computer. Even though I have the interface card plugged into one of the slots. I can't seem to get the hard disk to respond. The manufacturer of the drive is the First Class Company. Can you help me with this problem? — B. Fischer, Indi- anapolis. IN The company you're looking for is called First Class Peripherals and. the last time I dealt with them, they were located in Carson City, Nevada and their phone number was 800 538-1307. It's been a while since I had anything to do with them but, as I remember, they were always ex- tremely helpful. Your best bet is to get in touch with them and get the software and man- uals that were supposed to accom- pany the drive. If you can't do that, check with a local Apple user's group and see if anyone can help you there. The Sider (the name for their drives), was one of the first hard disks avail- able for the Apple II series of comput- ers and I have no doubt that they sold a lot of them. There are a few things you can try to make sure the drive is still working. You said that you had the card plugged into the computer, but there's a good chance you're not is- suing the proper commands to ac- cess it. When the Apple is first turned on, it checks the slots to try and find a disk controller card. Each slot has 256 bytes of memory in the main Ap- ple memory map, and each card is designed to work in a slot that has a particular signature that indicates its function. By examining these sig- nature bytes, the Apple is able to identify the cards connected to it. At powerup, the Apple wants to find a disk controller card and it scans through the slots looking for one. The scan starts at slot #7 (the one near- est the video connector), and winds up at slot #1 (the one nearest the power supply). As soon as the Apple finds a disk controller card, it turns control over to the firmware located on the card. What's important to real- ize is that the computer will recognize the first controller card it finds. If you have one in slot #6. it won't pay any attention Cat bootup) to any others in lower numbered slots. If you want to boot off the Sider. you have to put its controller card in a higher numbered slot than the one used for the regular disk drives. Since the disk controller is usually located in slot #6, the Sider's controller card should be in slot #7. As an alter- native, you can access the Sider by typing PR#X' at the Apple prompt (the "X" is the number of the slot in which you've put the Sider's control- ler card). Whichever method you choose, accessing the Sider should turn on its activity light and whatever boot pro- gram is on the disk should show up on your screen. Both DOS and Pro- DOS (the two main operating sys- tems for the Apple series of computers) have to be patched to work with the Sider and the only way to do that is by using the software that was originally supplied with the drive. VIDEO SYNC I'm building a video circuit and want to get the sync sig- nals from a standard com- posite wideo input. My ultimate goal is to be able to mix video signals together and, even though I have a good design for the mixer and sync gener- ator, I have to be able to identi- fy the sync on the incoming video. Any ideas? — C. Bald- win, Bangcock, Thailand Fortunately for you, what you're trying to do is fairly common. While it's possible to design your own sync separator, it would be a lot of un- necessary work because there are chips around that can do the job for you. Remember that stripping sync is something that's done in every TV set on the market and, as a result, semi- conductor manufacturers have jumped into the market with single- chip solutions to the problem. Sev- eral companies make them, but the one I usually use is the LM1881 made by National Semiconductor. I've found it very easy to put in a circuit and fairly tolerant of variations in sync levels and signal voltages. The pinouts of the chip are shown in Fig. 1 and I've also drawn in the components needed to make it work. As you can see, all it takes is two capacitors and one resistor. Nothing could be simpler but you still should write to National Semiconductor to get a data sheet for the IC (National Semiconductor Corporation. 2900 Semiconductor Drive. Santa Clara, CA 95052-8090). When you contact them, you should ask where you can get the part since I don't know what the avail- ability is like in your part of the world. You might find it easier to deal with a supplier in the United States but, no matter what you do, it's not a com- mon IC so you're going to have to do some investigating if you want to buy only one or two of them. Minimum orders can be murder. -..'.". ' ■ COMPOSITE. 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MI 49022 LT CL-807 E :f/^£s /a *5£& (4 /Z /S .0//uT /3 /6 "^S-Tz CA £ MX ALPHA [ftmtftem I 242-RE West Avenue, Darien, CT 06820 to Call (203) 656-1 806 or Fax 203 656 0756 CIRCLE 180 ON FREE INFORMATION CARD 17 JAN CRYSTALS CO 9 z o tr < your reliable source hr a world of crystal clear communication i i • Commercial Two-Way • Microprocessors • Amateur/ Experimental • Scanners/ Monitors/Pagers • Satellite-Telemetry • Plus custom applications EXPEDITED ORDER SERVICE! FOR FREE CATALOG, CALL OR WRITE: JAN CRYSTALS P.O. Box 06017 Ft. Myers, FL 33906 (813) 936-2397 TOLL FREE 1-800-526-9825 FAX ORDERS: 1-813-936-3750 VISA CIRCLE 104 ON FREE INFORMATION CARD EARN YOUR B.S.E.E. DEGREE THROUGH HOME STUDY Our New and Highly Effective Advanced- Place- men & Program tor experienced Electronic Tech- nicians grants credit for previous Schooling and Professional Experience, and can greatly re- duce the lime required to complete Program and reach graduation. No residence schooling re- quired for qualified Electronic Technicians. Through this Special Program you can pull all of the loose ends of your electronics background together and earn your B.5.E.E. Degree. Up- grade your status and pay to the Engineering Level. Advance Rapidly f Many finish in 12 months or less. Students and graduates in all 50 States and throughout the World. Established Over 40 Years! Write for free Descriptive Lit- erature. COOK'S INSTITUTE OF ELECTRONICS ENGINEERING ^SJ-w-E 4251 CYPRESS DRIVE *»■*■« JACKSON, MISSISSIPPI 39212 a hurdle, not an impasse. VLSI cir- cuits will soon permit multiple digital- and analog-signal-processing and de- cryption equipment all within the same receiver and/or the television itself. But all of this technical informa- tion is just the tip of the icebergl The article stated, "Since the same pool of feature films should be available to all the PPV hopefuls, and the majors promise to offer basic pro- gramming comparable to current basic cable ..." That's where the rest of the story begins. Most existing "cable" programming is controlled by very few MSO's or Multiple System Operators (giant cable companies), and/or by production companies that either own or are owned by MSO's. Those giants control programming and. more important, the major sources of programming. Since the networks want to be carried on cable in favorable channel spots C2-13), they are not a source of competitive programming. Without programming, the asser- tion "Satellite television received on small, flat antenna panels, promises to give cable TV a run for the money" ignores reality. Congress and many of us in the industry have wrestled with program-access problems for more than four years. Without program- ming, any technology that is not owned or at least controlled by cable interests will wither and die on the vine! ROBIN ADAIR Columbia, KY SPICE VARIETY I just finished reading T.J. Byers' article about SPICE in the November issue of Radio-Electronics, in which he mentioned PSpice and Is- Spice. I'd like to mention another product, called Micro-CAP II, which is a student version of the original Micro-CAP. It has all the capabilities of the original except that it is set up for only 25 nodes instead of 150 nodes. The student version has a vast built-in library for such compo- nents as op-amps, transformers, NPN and PNP transistors, MOS transistors, diodes, and more. It also includes a schematic editor, netlist, bode plots, time-domain plots, Fourier analysis, and more. The stu- dent version costs less than $50.00 and comes with a manual written for the non-professional. I found that to be much better than the sample ver- sions mailed out by PSpice or IsSp- ice. There is also a student version for digital circuits called Micro-Logic II. It also costs about $50. I just graduated from an electrical engineering program and I used both of those software packages exten- sively, with excellent results. Both book/software packages are avail- able from Addi son-Wesley Publishing Company (ISBN 0-201-50552-5: Micro-Logic II; ISBN 0-201-50542-8: Micro-CAP II). DONALD HAROOTUNIAN Webster, TX NTSC-TO-RGB CONVERTER Several incorrect statements ap- peared in Jim Harrigfeld's article "Build an NTSC-to-RGB Converter" (Radio-Electronics, October 1990). The subheading says, "Put a TV in your VGA monitor," and the text says that standard NTSC video rate requirements eliminate "most fixed-frequency (digital) monitors — i.e., most CGA and EGA types." Both statements are false. As a reference, I cite the Ask R-E column on page 12 of the same issue. To display a standard NTSC signal, a 15.75-kHz horizontal scanning rate is required. The table on page 12 shows that VGA does not use that rate, while CGA uses exactly that rate. In fact, CGA video was originally de- signed so that PC users could use their color TV sets as monitors. Please take care to make your arti- cles technically correct! I also agree with Mr. Burton ("Throwing Caution to the Wind," Letters, October 1990) that cautions about handling CMOS seem over- done. The first CMOS chips were indeed static sensitive, but manufac- turers quickly added input-protection diodes. EARL MORRIS Midland, Ml Both of the statements in which Mr. Morris finds fault appeared as a result of editing errors. The subhead, of course, should have read "Put a TV in your Multisync Monitor. " The text that Mr. Morris quotes is not as clear as it should be. The point we tried to make is that there are two requirements for a monitor: (I) that it accept analog inputs, and (2) that it be capable of scanning at 60 Hz ver- tical and 15. 75 kHz horizontal. Al- though a CGA monitor scans adequately, it generally has only dig- 18 CIRCLE 5fi ON FREE INFORMATION CARD ital inputs and thus will not work. An EGA not only scans at the wrong fre- quency but it also has digital inputs. And a VGA monitor, although it has analog inputs, will not scan at the correct rate. That's the reason for our recommendation for multi-frequency- type monitors.— JIM HARRIGFELD BRAIN POWER While I was not surprised that there were objections to Don Lancaster's claim of a four-billion-bit human brain capacity (Hardware Hacker, Radio- Electronics, January 1990), I was disappointed in the nature of the ob- jections (.Letters. May and November 1990), given the recent popularity of neural network research. While it is true that the brain compresses data, it is also true that the compression algorithms are part of the brain and (theoretically) could be mimicked by a computer. The real issue is that the "program" of the human brain is not totally contained in its four-billion neu- rons. It is the ten thousand (rough average) interconnections to each neuron that determine the "pro- gram." I'm not sure how much resolu- tion the analog connection strengths have, but I'll guess about 3-bits worth. Therefore, to mimic the brain, you would need and associative memory structure with a capacity of about (2 3 )(4x 10 9 )(1 x 10 4 ) = 3.2x10 14 bits. Keep in mind that many of the brain's functions have been efficiently "hard-wired" over a billion years of evolutions to avoid the waste of con- nections during trial-and-error pro- gramming. We are still a long way from constructing anything with the complexity and power of the human brain . GEORGE LEGTERS Melbourne Beach, FL CONSUMER ELECTRONICS FOR THE BLIND In response to David Plumlee's let- ter regarding electronic appliances for the blind (Radio-Electronics. November 1990), unless products with such features find widespread acceptance among the sighted, it's not very likely that they'll appear on the market. However, I would think that he could retrofit some appliances himself, or have it done for veiy little cost. "Dymo" label-making ma- chines include a model that produces Braille-character labels that can be placed over many touch controls. When used over a touch-control pan- el on a unit that has an audible signal when buttons are pressed, the beep and the Braille might be enough to provide reliable operation by the sightless. As for a clock radio, perhaps he could use a separate clock that chimes at the hour and each quarter hour. He could interface it with a radio to turn the radio on at the appropriate time. If that didn't work, maybe a talk- ing clock would be easier to use. Mark V Electronics (8019 E. Slauson Ave., Montebello, CA 90640) offers two such models. One other possible source of infor- mation is an organization called Christian Record Braille (RO. Box 6097, Lincoln, NE 68506). They make audio/visual products for the blind. Most of their products are Christian study and information ma- terials, but they might offer guidance in other areas as well, ROGER DOERING Camp Verde, CA 86322 R-E New B&K-PRECISION Parts resistors, transistors, diodes, There's no need to guess about components with ■ B&K-PRECISION's 815 Parts Tester. It accurately measures the most-used components and displays ■ their values H a large 0.8" LCD readout. Rugged ■ design and hit stand moke it well suited for field ■ or bench, ■ One look at this quality instrument will convince ■ you the B&K-PRECISION 815 is the best buy. For detailed specifications or immediate delivery, ■ contact your local distributor. ■ Tester checks capacitors, SCRs, LEDs and more. Tests capacitance from O.tpF to 20mF in capacitors, cables, switches,- other components. Tests resistance from 0.1 ohm to 20 megohms. Tests SCRs, diodes and LEDs. Tests transistor gain ond leakage. Tests batteries under true load conditions. 26 measurement ranges. 5 foot drop-resistont case. Tilt stond for bench use. Includes test leads M ^BKFH \M MAXTEC INTERNATIONAL CORP 1 Domestic and International Sales 6470 W. Cortland St., Chicago, I L 60635 312-889-1446 • FAX: 312-794-9740 Canadian Sales, Atlas Electronics, Ontario CIRCLE 77 ON FREE INFORMATION CARD m CD C > 3 19 Data Controls Analyst 2 Data Line Monitor 03 g z O cc i- o 6 < DC We've all had the experience of tiying to troubleshoot a PC's serial data line to es- tablish reliable communications be- tween a PC and external device such as a modem, printer, or serial-to-par- allel converter. It's usually a difficult job because you can't see what's go- ing on. Sure, you can use breakout boxes with LED indicators to try to get the lines matched up correctly but if the communications problem is caused by an incorrect transmission rate, glitches on signal lines, or an unreliable data-communications channel, simple tools just won't do the job. That's when you need a de- vice like the Analyst 2 data-line monitor and digital test set from Data Controls (2183 Buckingham Road, Suite 217, Richardson, TX 75081). The Analyst 2 is a handheld unit, but with a size of about 4'/s X8V4X 1 3 /4 inches, you'll proba- bly prefer to leave it on your benchtop. A wall transformer pro- vides power to the bottom of the unit through a detachable cable. The front panel features 8 function keys, a 2- line by 32-character backlit LCD readout, and eight tri-color LED's across the top of the unit. On power- up the Analyst 2 performs a self test, after which it's ready to test data lines. The main menu of the unit contains twelve choices for the appropriate mode of operation. Each mode is displayed one at a time, and the list is scrolled through using up or down cursor keys. Operating modes In the Data Monitor mode, the Analyst 2 can capture and display RS-232 serial data streams. Asynchronous, synchronous, or a user-defined bit-oriented protocol are supported, and the display can be in a character-oriented format or in hex- adecimal. To aid in troubleshooting, theAna/ysf2can be triggered to start recording when it sees a specific group of characters. Sub menus let you select the proper signal clocking, data format, how the data is stored in CIRCLE 10 ON FREE INFORMATION CARD Troubleshoot, test, and analyze data circuits quickly. the capture buffer, whether specific signal transitions are captured, and how the display should show the cap- tured data. The Review Data mode provides a way to examine and manipulate the data stored in the non-volatile capture buffer. As in the monitor mode, vari- ous sub menus are used to select data formats. The Distortion mode is used to de- tect the deviation of a signal's actual timing parameters from what it should theoretically be. Three types of distortion, gross, isochronous, and bias, can be measured. In the Time Delay mode, the Analyst 2 measures a device's re- sponse delay. It sends out control sig- nals, and waits for responses. For example, the length of time between a request-to-send CRTS) and the cor- responding clear-to-send CCTS) can be measured. The Analyst 2 can also act as a source of data in its Simulate mode, where it outputs data to verify that a data channel is working properly. It can also be used to test printers, modems, terminals, and the like. When requested the unit will output, in either ASCII or EBCDIC coding a QBF or quick-brown-fox message. which contains every letter of the al- phabet, the numbers through 9, a carriage return, and a line feed. As you might expect, data-framing and - format modes are selectable. To simulate a loopback device, the Analyst 2 can be run in its Echo mode. When running, the unit dig- itally loops back all data presented on pin 3 (receive data) onto pin 2 (trans- mit data). A bit-error rate test or BERT is pro- vided to determine the performance level of a data-communications line, and whether it can support communi- cations with an acceptable number of bit errors. Excessive line noise, crosstalk, and random burst errors on the line can be detected. A block- error rate test or BLERT is similar to a BERT, except that it specifically tests the capability of a data-communica- tions line to handle blocks of mes- sages of specific length. Another test mode — CERT or character-error rate test — is very similar to the BLERT mode, except that the block size is determined by the bits-per-character selection. A final rate-test mode — error seconds test — is used to deter- mine the performance of a data line over time. We found that putting the Analyst 2 to work was not too difficult — once we got the hang of it. Unfortunately, the operating manual supplied with the unit was difficult to decipher in many cases. For example, we were at first confused about the proper way to select the right choices from the menu. We did figure it out, but with- out help from the manual. All things considered, that's a minor complaint. We think that the $965. Analyst 2 data-line monitor is certainly worth a look from data-communications pro- fessionals. R-E 20 WILD THIS SSssg B£NCHJOP 3£B| FREQUENCY gam** COUNTER f & Ul lingual JTAk I .. .," ■ ■',' ,.,. ,i • v™ ■'■'. ■ Jfl-IB m L 74WrirmvtMiPi*i . . ' . ,.... .1 .1,1 Add /rtyquemry-mrasuremtnf capabilities to fiiur wwfrboFic/r ' ; .7 with this inexpensive counter. iMIW) III b**^T"i- W *j J» I i . ■' 'Lit 'L'n-iiJJ lut-r ll-i if in J |- L...I. .rmt.kBili i™l£-< id i.'i mi Hnmnr^ mmM UN ...... „ lfc' rrnM-nn ••uniff nJu lira; iJ« t ««rcrt» ) .n*-|nt'WW*H- r»&»' n < 4.(11, ■ri,!! i,*.rt ten MW \> T ■«# *v-m» Wf *#*** any o> ■ Wkllf Ihr .iilriuJ .. «1M u n ■ i i ^B.A.dilllibL, 4'/is INCHES In "Build This Benchtop Frequency Counter," (De- cember 1990) we were un- able to provide the PC-board foil patterns. They are re- produced here. We greatly exaggerated the capabilities of the coun- ter. Because of the compo- nents used, the counter cannot perform at frequen- cies above 25 MHz. We're sorry for any confusion our misstatements caused. ° ^ r ! rt ' | * li " t i >1>| * ll ' | * >1,f * t< " f * >M 't * 1 d . ^w^iii>iiitiftiihtit»f W ihtitif i . i[ ■4 ,s /w INCHES- Train at Home to be an Electronics Technician ! Professional training ant! equipment can help you qualify for a dynamic, high-paying career in your spare time. As the demand for computers and micro- processors in business and manufacturing continues lo grow, so does the need for qualified lechnicians. It's not unusual for ex- perienced technicians to cam from $35,000 to more than $40,000 a year.* Now there's a way you can Irain for this exciiing field without interrupting your job or homo life. Choose From These Programs of Study •Electronics & Microprocessor Technology •Industrial Electronics & Microprocessor Technology •Computer Servicing & Electronics Technology •Specialized Associate Degree In Electronics Technology You (Vet Professional Equipment For Professional Training Depending on the program you select, you'll perfect your skills using this advanced equip- ment, included in the price of tuition: r Sdmw U s Rurvau erf Li4vn 5tin^iu.-M • IBM-Compatible Personal Computer • Digital Multimeter • Digital Logic Probe • Elenco Oscilloscope Exclusive Extras That Enhance Your Training Peoples College introduces some training firsts to make your learning experience more complete: •Accelerated Learning System — a scien- tifically proven study system thai lets you learn faster and easier than ever before. •Optional One-Week Seminar — available with our advanced programs. Conducted on our campus near Orlando, Fla. Not required for graduation, but a valuable opporlunity to fine tune your skills with personal guidance. •Video Tutor Training Tapes — give you a permanent, visual record of informative lectures and close-up demonstrations. •Experience Labs — professionally designed experiments thai give you hands- on "bench" experience. •Industry Certification Training Guide — provided with three of our programs. Gives you first-hand insight into the examination you may lake for your professional license. For COLOR CATALOG Mail Coupon or Call TOLL FREE 1-800-765-7247 Pmgmm ojjemt only in United Stolen . Cwtadn. Pueno Rico mil Virgin Moods. No Ohligati,„i. \'„ sales prnum u-ill call. Our programs are accredited by the Accrediting Commission of the National Home Study Council 5< __ YES! I would like to know more about your training programs. Send a catalog to: Name Address City State 5 -Zip_ Peoples College OF INDEPENDENT STUDIES 233 Academy Drive • P.O. Box 421768 Kissimmee, FL 34742-1768 Mraitar, n.i.. !Vi>pk, t:mup Ft 0291 m DO C > 21 CIRCLE 192 ON FREE INFORMATION CARD EgEMME Use the Free Information Card for more details on these products. w o z o EC H -I 6 □ < PALM-SIZED CPU MOD- ULES. Measuring only 3.6 x 3.8 x 0.6 inches. Ampro's CoreModules are fully configured PC-com- patible CPU modules with memory, solid-state disk, serial and parallel I/O ports, real-time clock, and keyboard and speaker in- terfaces. The CoreMod- ule/XT (pictured) was intro- duced in late 1990; the CoreModule/286 and CoreModule/386 should be available in 1991. De- signed for embedded ap- plications, each module can be used alone as a component-like, PC-com- patible engine, or can be combined with Ampro's MiniModule expansion pe- ripherals to build complete systems. The CoreModule/XT is equipped with a CMOS- enhanced 8088-compati- ble microprocessor that operates at 9.82 MHz, and a full complement of PC- compatible DMA control- lers, interrupt controllers, and timers. It comes with two byte-wide sockets for EPROM, flash EPROM, static RAM, or NOVRAM memory that can be used as bootable, DOS-com- patible solid-state disk CSSD), eliminating the need for floppy drives. Op- CIRCLE16 ON FREE INFORMATION CARD tional utility programs auto- matically converts any disk-based PC software to SSD operation. The MiniModule expan- sion boards, which stack over or under the Cor- eModule. add configura- tion flexibility, allowing the addition of CGA, EGA. VGA, LCD, and elec- troluminescent flat-panel controllers; a 2400-bps modem; a LAN interface; and other capabilities. The MiniModule/FSS provides floppy drive, SCSI, and se- rial port controllers in one extremely compact pack- age. The CoreModule/XT ranges in price (to OEMs) from below $100 in quan- tities of 10,000 and up to $130 for quantities of 1000. A CoreModule/XT De- velopment Kit that includes the CoreModule/XT, MiniModule/FSS, Mini- Module/VGA, all cables, mounting hardware, man- uals, and DR DOS costs $100 in quantities of 100. The MiniModule/SSD costs $90 in 100's — Ampro Computers, Inc., 990 Almanor Avenue, Sunnyvale, CA 94086; Tel: 408-522-2100; Fax: 408-720-1305. OVERHEAD IONIZER. To neutralize static charges on the workbench without taking up bench space, Desco's model A60420 ionizer mounts overhead and plugs into a standard AC outlet. The ionizer of- fers an automatic shut- down feature that turns the unit off if proper ionizing conditions cannot be main- tained, A built-in alarm cir- cuit continuously monitors CIRCLE 17 ON FREE INFORMATION CARD ion production and ensures proper balance. A variable speed control adjusts three fans that move the ions to- ward the work surface. The A60420 overhead ionizer costs $630. — De- sco Industries, Inc., 761 Penarth Avenue, Walnut, CA 91789; Tel: 714-598-2753; Fax: 714-595-7028. HF SWR ANALYZER. Providing a complete pic- ture of an antenna SWR over an entire band— with- out a transmitter, SWR meter, or any other equip- ment—the MFJ-207 HF SWR analyzer makes it easy to set up and pre- cisely trim an antenna. It is used by plugging the an- tenna into the coax con- nector, setting the analyzer to the desired frequency, and reading the SWR. The battery-operated, hand- held unit can be brought to the antenna to directly measure its SWR without the distorting effects of the coax. SWR changes can be monitored while adjust- ments are being made, and the user can immediately CIRCLE 18 ON FREE INFORMATION CARD see the effects of shorten- ing or lengthening the di- pole. The user can instantly check multi-band dipoles and trap verticals to see if the low SWR points are po- sitioned correctly, and ad- just the antenna until they are right. The MFJ-207 helps locate the best place on a car to mount a mobile antenna. In addition, it can be used to observe the effects of rain or snow on the beam or dipole, tune up 22 Discover Your Career Potential In The Fast Growing Field Of High-Tech Electronics! CIE Gives You The Training You Need to Succeed... At Your Own Pace...& In Your Own Home! If you're anxious to get ahead ...and build a rea/ career... you owe it to yourself to find out about the Cleveland Institute of Electronics! CIE can help you discover your career potential in the fast growing field of high-tech electronics. A career that will challenge and excite you every day... reward you with a powerful feeling of personal accomplishment... and deliver a level of financial security you may have only dreamed of before! 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As you advance, CIE makes job opportunities available to you through the bimonthly school paper. The Electron. Consumer Electronics Military Electronics Personal Training From A Renowned Faculty. Unlike the impersonal approach of large class- room study, CIE offers you one-on-one instructional help 6 days a week, toll-free. Each CIE lesson is authored by an independent specialist, backed by CIE instructors who work directly with you to answer your questions and provide technical assis- „__ tance when you need it. Practical Training... At Your Own Pace. Through CIE, you can train for your new career while you keep your pres- ent job. Each course allows a gener- ous completion time, and there are no limitations on how fast you can study. Should you already have some electronics experience, CIE offers several courses which start at the intermediate level. "State-Of-The-Art" Facilities & Equipment In 1969, CIE pioneered the first elec- tronics laboratory course, and in 1984. the first Microprocessor Laboratory. Today, no other home study school can match CIE's state-of-the-art equipment. And all your laboratory equipment is included in your tuition cost. There is no extra charge— it's yours to use while you study at home and on the job after you complete your course! Earn Your Degree To Become A Professional In Electronics! Every CIE course you take earns you credit towards the completion of your Associate in Applied Science Degree, so you can work towards your degree in stages. And CIE is the only school that awards you for fast study, which can save you thousands of dollars in obtaining the same electronics education found in four-year Bachelor's Degree programs! Write for details today! Send For Your Catalog Today! CIE World Headquarters *%5f Cleveland Institute of Electronics, Inc. 1776 East 17th St., Cleveland. Ohio 44114 □ YES! Please send me your independent study catalog (For your convenience, CIE will have a representative contact you— there is no obligation.) Apt* Area Code; Phone No. Check box for G.I. Bill bulletin cm educational benefits: o veteran o Active Duty Mail This Coupon Today! AE03 sS&P 5, Phase Shift Circuit using built-in oscilloscope Easy to use, menu-driven, mouse controlled circuits come alive on your terminal! DC Series Circuits Ohms's Law ■ Kirchhoff's Voltage Law Temperature Effects Voltage sources • Resistances in series Voftage Dividers nternal source resistance Voltage regulation DC Parallel Circuits Networks • Current dividers DC Series-Parallel Circuits DC Circuit analysis by reduction DC Circuit Analysis Mesh circuit and branch current analysis Superposition Theory Circuit analysis using superposition Bridge Circuits Delta - Wye conversions Phasor Mathematics Phaser theory Series AC Circuits RC, RL and RLC circuits Power and power factors Resonance Tuned series circuits Parallel resonance Parallel Resonance Tank circuits Polyphase Systems Power in polyphase systems comP build a uter si ctron" cS mul^l^rcuits- nd test ac tua' New PROTOLAB™, a state of the art electronics lab for the hobbyist's, student's or engineer's pc. Now, you can build and experiment with actual circuits, choosing from an unlimited number of components, including resistors, capacitors, inductors, general impedance, AC voltage sources, batteries, AC/DC current sources. Then, analyze your circuits with built-in high tech instruments — voltmeter, ammeter, ohmmeter, oscilloscope, wattmeter, sweep generator, breadboard, temperature adjustment and frequency control. This complete electronics lab, simulates thousands of dollars worth of parts and instruments ... all built-in with easy to use, menu driven, mouse controlled PROTOWARE™ software. Plus, you get a unique experiment book, featuring over 75 experi- ments and circuits. Enjoy countless hours of fun, while learning. And, you won't blow up your "lab", because it's fool proof and safe on your pc. Here are some typical circuits you can build and test. Frequency Compensated Bridge using oscilloscope to measure AC sign a offset by DC voltage Order today... start building and testing circuits today... Complete, for IBM/compatibles*... ONLY $99*" For Macintosh with high resolution, enhanced graphics"... 'IBMfcompatibJes require 384K HAM. CGA [640x200] video display and mouse "Macintosh requires Macintosh 512E. MAC XL, MAC PLUS, MAC SE, MAC I Call toll-free for details GLOBAL Global Specialties. 70 Fulton Terrace. New Haven, CT 06512. 1Qf\f\ C70 "i HOQ CDC/**I AITICC Telephone: [203] 624-3103 Mnierplei Electronics. 1990. " OUU "O I C.~\ U<£0 drEvlALI ICO All Global Specialties breadboard! ng products made in USA. CIRCLE 186 ON FREE INFORMATION CARD o z o - \- o g < £ an antenna tuner without transmitting, or check the SWR of a linear amplifier's input. The SWR analyzer has a low-distortion RF gener- ator that covers 10-160 meters, an SWR bridge that gives forward and re- flected components, and it automatically computes and displays the SWR. A frequency-counter output allows a counter to be con- nected for precise digital readout. Operation is com- pletely automatic. The MFJ-207 HF SWR analyzer costs $99. — MFJ Enterprises, Inc., P.O. Box 494, Mississippi State, MS 39762; Tel: 601-323-5869; Fax: 601-323-6551. HANDHELD LOGIC ANALYZER. Targeted for use by design engineers and field service techni- cians, Trace-Tek's Logic Boy is a full-featured. 16- channel, 50-MHz logic ana- lyzer. The handheld diag- nostic and development CIRCLE 19 ON FREE INFORMATION CARD tool is easy to use, with ex- tensive menus for user prompting and system set- up. All state information, timing data, and menus are displayed on the LCD read- out. The Logic Boy weighs only 21 ounces with NiCd batteries installed, and is designed to be held and operated with one hand — a convenience when trou- bleshooting digital circuits at remote locations lacking AC power. It can be cou- pled with a battery-oper- ated printer to form a complete portable diag- nostic and troubleshooting system. The Logic Boy offers 50- MHz operation on all 16 channels, non-volatile sys- tem setups and reference memory, a built-in IBM- compatible printer port, and a BNC trigger output terminal that lets the logic analyzer be used as a four- level word recognizer when connected to the external trigger input of most os- cilloscopes. The Logic Boy is compatible with both TTL and CMOS logic levels, and features 1Kx16 cap- ture-and-reference memo- ry, synchronous or asyn- chronous clocking, a clock qualifier, and programma- ble trigger delay. The Logic Boy. complete with probes, AC wall adapt- er, IBM printer-cable adapt- er, NiCd batteries, and a one-year warranty, costs $1795.— Trace-Tek In- struments, 1301 North Denton Drive, Suite 204, Carrollton, TX 75006. GRAPHIC POWER MONITOR. To help elec- tronics technicians and hobbyists find and solve power problems, the PowerVisa power monitor detects all power distur- bances that can affect electronic equipment. By simply plugging it into an outlet, a complete power analysis can be made. When any type of power disturbance — including CIRCLE 20 ON FREE INFORMATION CARD sags, surges, impulses, failures, waveshape faults, frequency errors, high-fre- quency noise, wiring er- rors, and total harmonic distortion- — is detected, an LED lights. A disturbance graph can be printed imme- diately or, at the users' con- venience, a text report of the ten worst events of each disturbance type can be generated. The" PowerVisa also prints daily and weekly summaries. It monitors true RMS AC voltage. AC current, and temperature. An RS-232 port is included for remote operation. The instrument automatically selects ap- propriate thresholds de- pending on the voltage being monitored, or the user can choose to man- ually set the desired thresholds, "Help" messages that explain its operation can be printed, and a push of the Advice button generates a printout of the types of dis- turbances that have been recorded and the times they occurred. The PowerVisa power monitor has a suggested price of $3,295. — Basic Measuring Instru- ments, 355 Lakeside Drive, Foster City, CA 94404; Tel: 415-570-5355; Fax: 415-574-2176. BI-POLAR POWER SUP- PLIES. The POW series of single-output, bi-polar power supplies can "sink" — absorb current from external sources — or "source" — supply power to external loads — current. They can be used for ap- plications involving servo systems and precision drives, as variable output power supplies, or as power amplifiers with fre- quencycharacteristics ranging from ± 30 kHz. The power supplies are available with three dif- ferent operating ranges: + 35 to -35 VDC at 1A: + 35 to -35 VDC at 5 A; and +70 to -70 VDC at 2A. Without switching po- larity, both gain and positive/negative voltage can be varied continuously by adjusting panel- mounted. 10-turn potenti- ometers. Constant-current crossover overload protec- tion is provided. The power supplies are CIRCLE 21 ON FREE INFORMATION CARD available with either a top luggage strap for portability, or a built-in rack- mounting frame. The POW series of sin- gle-output, bi-polar power supplies are priced starting at $925— Kikusui In- ternational Corpora- tion, 19601 Mariner Ave- nue. Torrance, CA 90503; Tel: 800-KIK-8784. SURFACE-MOUNT SOL- DER KITS. Two SMT sol- der cream kits, for evalua- tion of component solder- ing using different types of flux systems, each contain 250-grams of stencil-grade solder cream packed in five CIRCLE 22 ON FREE INFORMATION CARD 50-gram "Flexpaks." The five different types of mildly activated fluxing systems included are standard, fine pitch, water washable, and two with no-clean residues. The latter leave clear, hard, 28 non-corrosive residues; one is off-fillet residue and the other is on-fillet resi- due. Kit 7 provides the flux systems with an Sn62 al- loy, while Kit 8 is supplied with an Sn63 alloy. Each kit comes with a "Vac- Tweezer" set that includes a vacuum pickup and five tips with various sizes of clear pads. Surface-mount solder Kit 7 and Kit 8 are priced at $89 each.— ESP Solder Plus, 14 Blackstone Valley Place, Lincoln, Rl 02865; Tel: 800-338-4353. DIGITAL CLAMP-ON METER. The model ACD-10 clamp-on meter di- rectly measures AC cur- rent, voltage, and resis- CIRCLE23 0NFREE INFORMATION CARD tance. The drop-proof in- strument weighs eight ounces and is 6% inches long. Its half-inch display provides over-range and low-battery indicators. The autoranging meter pro- vides circuit protection up to 550 volts. The ACD-W comes with a wrist strap and a removable belt clip. A 9-vo!t battery, safety test leads, a carrying case, and instructions are included. The model ACD-10 dig- ital volt/amp/ohm meter has a list price of $89.95 — Amprobe Instrument, 630 Merrick Road, P.O. Box 329. Lynbrook, NY 11563; Tel: 516-593-5600. HARD-DRIVE SECURI- TY SYSTEM. Providing password access security For IBM PC, XT, AT, 386, and compatible comput- ers, PC Access version 2. 1 consists of an easily-in- stalled plug-in card and a CIRCLE 24 ON FREE INFORMATION CARD diskette of programs. Ei- ther a valid password or, optionally, a user-ID and a password must be entered each time the computer is booted before DOS will be loaded or executed. One master password and as many as 15 user pass- words are allowed. The master password must be used to access the user password list and to select the security system's func- tions. Version 2.1 features menu-driven selections for establishing the pass- words and other security settings, DIP switch selec- tions of the security board's address, and a half- size card with a bracket for easy installation. PC Ac- cess does not modify COMMAND.COM or any system files, and does not interfere with the operation of any other software. PC Access version 2. 1 has a suggested list price of $79; distributor and quantity discounts are available . — Ren ton Products. P.O. Box 16271, Seattle, WA 98116; Tel: 206-682-7341. RADIO-FREQUENCY FINDER/COUNTER. The model 1500A RF finder/ counter from Startek runs CRAMOUN DeOxidize; IMPROVES CONDUCTIVITY DEOXIDIZES • CLEANS • PRESERVES • LUBRICATES hi All Metals, induing Gold I tRAMOLIN^ DeQxfdizer improves conductivity hy dis- solving oxides Ittot tarn on metal connector and con- tort surfaces, eliminating unwarned resistance that impedes electrical performance. CRAMOUN 3 is an active ingredient that does not rely on solvents for performance. Due to the excel- lent migration properties, CHaMOUN 3 coots the entire meiol surface ond protects it from future oxMotion. [RAMOLiN" continues to be the most effective ond economical product for improving and mointoining electrical component reliability. fOR MANUFACTURE, MAINTtNAHCE AND SERVICE OF: • Switches & Reloys • Coble Connectors I Adaptors • Edge Connectors • Terminal Strips * Plugs £ Sockets • Gold Fluted Connectors • Potentiometers • Battery Contorts USED BY THOSE WHO DEMAND THIBIST: • Bell £ Howell < Capitol Records • Dolby loborolories • Hewlett Packard • John Fluke Mfg. • Mcintosh tabs •MCI (Sony) • Motorola • NASA ■ Nokomicfii • RCA • Switr.hr.raft • ond Mony More, I LABORATORIES. INC. f n wanmentnlty Conscious - RO.BcwJ bcortjrjatt 920333679 (619)743-7143 Wtttl?) 743-2460 CIRCLE! 50 ON FREE INFORMATION CARD KENWOOD OSCILLOSCOPES AM UK OSCILLOSCOPES H/0 RLADOUT HOOEL CS-5135 40 NHi, Dual Channel , Delayed Sweep. REG. JR9C Cfi SALE $719. 95 MODEL CS-S1SS 50 HHl, 3 Channel , 6- T rate. Delayed Sweep. BEG. 1995. OC SALE $819.9$ MODEL CS-5165 61". M-!:. 3 Channel, 6-trace, Delayed Sweep. KEG. IMB.OO SALE 1899.95 NOOEL CS-2150 150 HHl, < Channel, 8-Traee, Delayed Sweep. REG. 12395.00 SALE 11495.95 WWLOS OSCILLOSCOPES wVftEADOUT/LUKiORS WOEL CS-5130 ■0 mi, Dual Channel, e-Trace, Delayed Sweep. REG. 11095.00 SALE KM. 95 MODEL CS-S170 100 mi. Dual Channel, *-Traee, Delayed Sweep. REG. 11694.00 SALE 11399.95 HOOEL CS-M10 100 KHz. a Channel . 10-lrece, DelayeG Sweep. REG, 11995. 00 SALE 11699.95 WOEL CS-WM 150 mi, ' Channel. lO-Trace, Delayed Sweep. REG J?3S?.0,i SALE 11999.95 SB Ha k >• |- ' " t> ci it HODEL CS-40HS ?n I1H2, Dual Channel Oscilloscope. AEG. 1195.(10 SALE $349.95 INT Products International 8931 Brookv i 1 1 ,- M. Silver Spring, W 20910 (80O}638-?O?O (301)587-78?4 FAX! 301-S8S-S402 EAST ORDER FAX LINE (B00)5*5-0058 800-638-2020 CIRCLE 182 ON FREE INFORMATION CARD CABLE - TV SIGNAL REA4CVERS ■FOB ELIMINATION OF SEVERE INTERFERENCE ■FOR -CENSORING" OF ADULT BROADCASTS /W ■■ ; SICIJAl ELIMINATOR ff> • ATTENUATION - 45 dB TYPICAL ■ BANDWIDTH - A MHl AT 5 fJB POINTS ■ INSERTION LOSS -2 6B MODEL RANGE FOB CHANNELS PASS BAUD PHCE shipping Z3K 50-66 MHz 2.3 |or6 mtitrhim) W-OOO MHi Mi HO SHIPPING or C.0,0. CK4.HGES 46 FM 66-1 OB MHr ■ 5 ■'■ ■' r.-r, ■''.' 60-300 MHz iao 1417 120-144 MHz •*m 15(B) 1«|C)17|D) 50-400 MHz sac 1822 m-17«MKl 18(E) 19|F) 20(G) 21(H)22(I) 50-400 MHz too 713 171-216 MH! 7.8-9.10.11. 12.13 F,:i 4CL1 Mh; $30 3 for $75 - 1 for $200 - mix or match CALITOLL FREE FOR C.O.D. OR SEND CHECK TO ORDER FASTDELIVERY 30 D A Y M ON E Y BACK G U AR ANT EE ( 3 F ILTE R L IM IT) Star Circuits P. O. Box 94917 Las Vegas, NV89193-4917 1-800-433-6319 Be an FCC LICENSED ELECTRONIC TECHNICIAN! No costly school. No commuting to class. The Original Home-Study course prepares you for the "FCC Commercial Radio- telephone License." This valuable license is your professional "ticket" to thousands of exciting jobs in Communications, Radio- TV, Microwave, Maritime, Radar, Avionics and more.., even start your own business! You don't need a college degree to qualify, but you do need an FCC License. co No Need to Quit Your Job or Go To School y This proven course is easy, fast and low g cost! GUARANTEED PASS— You get you o; FCC License or money refunded. Send to j- FREE facts now. MAIL COUPON TODAY uir -I I q! §■ en comrndMD productions FCC LICENSE TRAINING, Dept. 90 P.O. Box 2824, San Francisco, CA 94126 Please rush FREE details immediately t 30 1 I HAME ADDRESS . CITY . STATE _ Try the t#ecirf7fjff's> bulletin board system (RE-BBS) 516-293-2283 The more you use it the mare useful it becomes. We support 300 and 1200 baud operation. Parameters: 8N1 (8 data bits, no parity, 1 stop hit) or 7E1 (7 data bits, even parity, 1 stop bit). Add yourself to our user tiles to increase your access. Communicate with other R-E readers. Leave your comments on R-E with the SYSOP. RE-BBS 516-293-2283 on 110 VAC, 12 VDC, or rechargeable NiCd bat- teries, and is small enough to fit in a shirt pocket. It is housed in a rugged anodized-aluminum case and weighs less than 9 ounces with the batteries installed. The highly sen- sitive instrument can be used with its telescoping RF antenna to accurately and easily identify and measure transmit frequen- cies from handheld, mobile, or stationary radio transmitters. The 1500A has two over- lapping ranges — 1-500 MHz and 200-1500 MHz. Two "gate" or "sample" times are switch selecta- ble. A fast gate time of CIRCLE 25 ON FREE INFORMATION CARD 0.25-seconds yields a 1- kHz resolution, and a slow gate time of 2.5 seconds yields a 100-Hz resolution. A TXCO timebase provides accuracy of ± 1 ppm. The unit can be operated and charged simulta- neously with a 9 ± 12 VDC, AC adaptor. The in- put signal of the device is coupled via a BNC con- nector on the top, and vari- ous types of probes and antennas can be used to optimize performance for specific uses and frequen- cy ranges. The model 1500A radio- frequency finder/counter costs $99.95, the factory installed NiCd batteries cost $20.00, and an AC adapter/battery charger costs $9.00— Startek International, Inc., 398 NE 38th Street, Fort Lauderdale, FL 33334; Tel: 800-6 38-8050 or 305-561-2211 ; Fax: 305-561-9133, ANTENNA STATIC DIS- CHARGER. Precipitation static and corona dis- charge noise, which can raise the noise level 20 to 30 dB above ambient, are bled off by the model AS-? antenna static discharger, CIRCLE 26 ON FREE INFORMATION CARD which reduces the un- desired electrical noise that causes receiver de- sensitization. The AS-1 is the same type of device that's used on aircraft and in ground stations to mini- mize electrostatic inter- ference. It has been modi- fied for use on antennas to prevent any detuning, even if it is element mounted. The antenna static dis- charger mounts easily to any antenna, boom, or tow- er and weighs only one ounce. It offers increased range during noisy condi- tions, minimized receiver desensitization, and lower antenna noise on long wires, dipoles, yagis for HF through UHF, verticals, TV, and TVRO antennas. The AS-1 antenna static discharger costs $12.95. — Static Buster Inc., 3535 Shepherd sville Road, Elizabethtown, KY 42701; Tel: 502-769-2244. R-E NEW LIT Use The Free Information Card for fast response. PASSPORT TO WORLD BAND RADIO; from In- ternational Broadcast- ing Services, Ltd., Box 300, Penn's Park, PA 18943; $16.95. This magazine in book format could be described as the TV Guide for radio. National Geographic. Consumer Reports, and CIRCLE 27 ON FREE INFORMATION CARD Time rolled into one. Its 384 pages are filled with ar- ticles on topics ranging from music behind the Iron Curtain to how to write to radio stations for free goods, from international politics and current events to how to get started in world-band listening, from Alistair Cooke's long-run- ning Letter From America show to the Salt Lake City world-band station that broadcasted rock-n-roll used by American troops in Panama to drive Noriega nuts. In-depth consumer reports provide com- parative ratings of portable and table-top radios, as well as a review of a world - band receiver for cars. Comprehensive program guides are listed by time, country, and channel. New- comers to the hobby will appreciate tips on what features to look for in a world- band receiver, a glos- sary of terms, and informa- tional articles. Inter- spersed throughout the book are helpful hints, defi- nitions, and pointers, along with intriguing photographs from around the world and dozens of advertisements for radio stations and equipment. 1991 ELECTRONIC COMPONENTS/COM- PUTER PRODUCTS CATALOG; from Jam- eco, 1355 Shoreway Road, Belmont, CA 94002; Tel: 415-592-8097; Fax: 415-592-2503; free. Featuring just about ev- erything the electronics en- thusiast or computer buff CIRCLE 28 ON FREE INFORMATION CARD could need, the new Jam- eco catalog offers tools, test equipment, cables, connectors, IC's. mother- boards, computer kits, floppy- and hard-disk driv- es, computer accessories, and more. New to this edi- tion of the catalog are two 386 computer kits. 386 motherboards, a 2400- baud mini external modem, and a 9600-baud fax board. The Jameco catalog fea- tures full product descrip- tions, photographs, and pricing information. TONER CARTRIDGE RECHARGE: Kits-Sup- plies-Service; from Chenesko Products Inc., 62 North Coleman Road, Centereach, NY 11720; Tel: 800-221-3516 or 516-736-7977; Fax: 516-732-4650; free. CIRCLE 29 ON FREE INFORMATION CARD With the high price of new toner cartridges for laser printers, many people prefer to use cartridges that have been cleaned out. modified, and re- charged. This catalog of- fers toner-cartridge re- charge products and ser- vices, and explains how to recharge cartridges used with laser printers including the HP Laserjets. Apple LaserWriters, and many others. Six do-it-yourself kits include full instructions for recharging. For those who want to start a re- charge business, the cata- log offers a complete selection of products — in- cluding generic toner, graphic toner, fixing rods, sealing strips, plugs, bags, tools, and vacuums — at bulk prices. For those who aren't handy with toner car- tridge recharging, or are short on time, the catalog offers a mail-in recharging service. SOLDER CREAMS: A COMPLETE GUIDE TO THE SELECTION AND USE OF SOLDER CREAM; from Multicore Solders, Cantiague Rock Road, Westbury, NY 11590; Fax: 516-334-7098; free with request on company let- terhead. This comprehensive 24- page brochure explains and describes the formulation. application methods, and uses of solder creams. It covers the various alloys, fluxes, properties, and rhe- ology of solder creams for surface-mount applica- tions, as well as techniques for deposition, reflow sol- dering, and cleaning. A chart that illustrates good A compete guide to the selection and use of Soi der Cream CIRCLE 30 ON FREE INFORMATION CARD working practices is fol- lowed by explanations of how to apply solder creams m for various purposes. A § three-page glossary of > commonly used technical ^ terms is also included in ^ the booklet. 2 31 Electronics Engineers & Designers! Take any 3 books for only A 95 (Values to $119.40) SHARPEN YOUR SKILLS— With Quality, Affordable Professional Books COMPUTER SCIENCE ENGINEERING MATH 3059 $34,95 Master [he art of modeling, ren- dering, and animating on your IBM* PC. 524 pp. Counts as 2. 10015 $42.95 The most up-to-date introduction available on the many facets of ISDN. 320 pp. Counts as 2 Almrithms onuraphs 32, 9321 $49.50 This lime-saving, handbook pro- vides problem-solving calcula- tions for engineering design, production and research, 416 pp. Courtis as 2 3429 $29.95 Your source for well-developed, ready-to-use computer algorithm codes, 180 pp. 8225P $19.95 Tested programs for most mathematical computing needs. 233 pp. 5t ■ | K H Jetworking vith fovetl Netware \.LAN vlanager's latidbcok In in ii ii 1 «oi.i w*r | 1 1 T :TYT"tM l ttl A at TlTljDHI L'J Design *.' Handbook _'f : Principles of Computer Dtxigtt •UILE TOU3 OWN 80386 IBM C0MEMBLE AND SAVE A BUNDLE 3283 $28.95 Covers all aspects of LAN plan- ning installation, and operation, i nc I ud ing standard and non- .standard arrangements. 240 pp. 3237P $24.95 This handy guide demonstrates such advanced features as debugging applications and Virtus! 8086 Mode. 432 pp. 9813 $39.95 Covers logic design, register transfer design, architecture, programming and more. 578 pp. 3131 $26.95 Assemble your own powerful microcomputer system . . . it's easy and inexpensive. 224 pp. 3279 $36.95 Master the proven repair tech- niques of an expert electronic technician. 570 pp. Counts as 2 ELECTRONIC CIRCUITS & COMPONENTS &8£t8L igp* THE mCTCWPWOf ■ ELECTRONICj "CIRCUITS VOLUME ONE "1 3258 S27.95 Stcp-by-stcp instructions for troubleshooting and repairing the latest in electrical equipment. 3I0 pp. 1 938 $60.00 Over t ,300 useful and versatile electronic circuit designs. 768 pp. Counts us 2 3138 $60.00 More than 700 state-of-the-art electronic circuit designs for on- the-job use. 738 pp. Commas 2 9243P S12.95 This book will eliminate the guesswork in choosing the best circuit or tracking down mal- functions in a completed circuit. 282 pp. 2672 S49.50 Linear integrated circuits — specifications, prices & data. 614 pp. 32 STATE-OF-THE-ART 3203 An indispensible guide to tech- nology from composition to ap- plications and testing. 400 pp. Counts as 2 $44.50 "244P $18.95 $29.95 -W8 This revised and updated edition is both a comprehensive. industry-wide reference, and a valuable collection of project ideas. 512 pp. 3329 A practical introduction to the latest devices, techniques, and shielding methods. 239 pp. A comprehensive overview of CAD/CAM, CAE. and CIM concepts, capabilities and appli- cations. 438 pp. Counts as 2 9340 $44.95 High-performance design tech- niques for today's high-speed logic devices. 272 pp. Counts as 2 3151 $39.95 Provides detailed insight into every aspect of the engineering design process— from the pre-concept phase through the life-cycle costs and commercial applications. 334 pp. Counts as 2 3037 $24.95 Build your own neural network- ing breadboards— systems that can store and retrieve like the brain! 160 pp. 9290 $36.00 Provides many never-before- published troubleshooting techniques and case histories. 315 pp. Counts os 2 INDUSTRIAL TECHNICIANS $44.50 3321 $24,95 A valuable workbench compa- nion covering industrial hard- ware theory and application. 334 pp. SWUCttWODE POW>»SUPP1Y H4NDBOOKI&, 9305 $59.30 The solution-oriented handbook for practicing engineers at all levels. Contains hundreds of informative illustrations and diagrams demonstrating key principles. 600 pp. Counts as 3 How the Club Works: ! SEND NO MONEY NOW! YOUR BENEFITS: You gel 3 books for $4.95 plus shipping & hand- ling when you join. You keep on saving with discounts of up to 50% as a member. YOUR PROFESSIONAL BOOKSTORE BY MAIL: Every 3-4 weeks, you will receive Ihe EE&D Book Club News describing the Mam Selec- lion and Alternates, as well as 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 selection at all, simply indicate your choice on the reply form provid- ed. You will have at least 10 days to decide. As a member, you agree to purchase at least 3 books within ihe next 2 years and may resign at any time thereafter. BONUS BOOKS: Starting immediately you will be eligible for our Bomts Book Plan with savings of up to 80% off publishers' prices. IRONCLAD NO-RISK GUARANTEE: If not satisfied with your books, return them within 10 days without obligation! EXCEPTIONAL QUALITY': All books are quality publishers" editions especially selected by our Editorial Board, All books are hardcover unless number is followed by a "P" tor paperback. (Publishers' Prices Shown) ©1991 EE4D BC. Slue Ridge Summit, PA 17294-0860 INTRODUCTORY 10-DAY FREE EXAMINATION ELECTRONICS ENGINEERS & DESIGNERS BOOK CLUB SW Blue Ridge Summit, PA 17294-0860 DYES! Please accept my membership in the ELECTRONICS ENGINEERS & DESIGNERS BOOK CLUB and send my 3 volumes listed below billing me $4.95, If not satisfied, I may return the books within 10 days and have my membership cancelled. 1 agree to purchase 3 or more books at regular Club Prices during the next 2 years, and may resign any time thereafter, A ship- ping/handling charge and sales tax will be added to all orders. Name Address Cirv State Zip Phone Signature valid tar new members only. Foreign applicant will receive special ordering irislruclBOns. Canada must remil in U.S. currency. This order suojecl to acceptance by rrie Etactittnrcs engineers ft Designers Book Club. DRE291 m c > ID < 35 ELENCO & HITACHI PRODUCTS AT DISCOUNT PRICES # tffr RSOs (Real-Time & Storage Oscilloscopes) From HITACHI The RSO - its the new solution View, Acquire, Test, Transfer and Document Your Waveform Data % fc Compact Series Scopes 4-Chonnel, lOOMS/s Model Introductory Ptice lOOMS/s (25MS/S or * channels simultaneously), 100MHz, 4lu*x 1ch.. 2kw i2cri.. 1fcw x 4ch. VC-0145 S 4,695.00 Compact, Full Feature Models 40MS/S. 100MHz, 4kwx1ch., 2kwx2cti. VC-6045 S3. 049. 00 20MS/S. SOMHz, 2kw x 2ch. VC-602S $ 2,295.00 fO \ Low Cost/High Value Models 20MS/s h 50MHz, 2kw x 2ch. VC-6024 $ 2,045.00 20MS/S, 20MHz, 2kw x 2ch. VC-6023 $ 1 ,749.00 RSOs from Hitachi feature such functions as roll mode, aver aging, save memory, smoothing, interpolation, pretriggering, cursor measurements, plotter interface, and RS-232C interface. With the comfort of analog and the power of digital v - 212 Hitachi Portable Scopes $435 DC to 50MHz, 2-Chemnel, DC offset DC ioSomhi 'unction, Alternate magnifier function Dual Channel V-525 CRT Readout, Cursor Meas, $1 ,025 w V-523 Delayed Sweep S99S V-422 40MHz Dual Tract |735 V-522 Bask; Model SB95 Delayed Sweep Lightweight (1 3 lbs) ZmV Sans 3 ¥r Warranty Modal V-1 065 Shown This series provides many new functions such as CRT Readout, Cursor measurements (V-1 085/1065/665), Frequency Ctr [V-1 085), Sweeplime Autoranging and Trigger Lock using a 6 -inch CRT. You don't feel the compactness in terms of performance and operation. V-660 60MHz Dual Trace V-665 60MHz Dual Trace w/Cursor V-1 060 100MHz Dual Trace V-1 065 100MHz Dual Trace w/Cursor V-1 085 1 00MHz Quad Trace w/Cursor V-1100A 100MHz Quad Trace w/Cursor V-1 1 50 1 50MHz Quad Trace w/Cursor $1,195 $1,345 $1,425 $1,695 $2,045 $2,295 $2,775 20MHz Elenco Osc illoscope $375 MO- 1251 • Dual Trace • Component Teslet • 6* CRT • X-Y Operation • TV Sync • 2 p*1 Probes FREE DMM with purchase of ANY SCOPE SCOPE PROBES P-l 65MHz. tx, lOx S19.95 P-2 100MHz, Ix. lOx S23.95 Elenco 35 M Hz Dual Trace * . Q _ Good to 50MHz $495 MO- 1252 - High luminance 6" CRT • ImV Sensitivity • SKV Acceleration Voltage • 10ns Rise Time • X-Y Operation ■ ZAxis • Delayed Triggering Sweep • Includes 2 P-1 Probes ;*r-^/ ; j-* F | All scopes include probes, schematics, operators manual, and 3 year (2 yrs for Elenco scopes) world wide warranty on parts & labor. Many accessories available tor all Hitachi scopes. Call or write tor complete specifications on these and many other fine oscilloscopes. WE NOW CARRY COMPLETE LINE OF FLUKE MULTIMETERS Models 21F 83 23F 25F 27F 73 75 77F 85 87 8050A 8060A 8062A + More CALL FOR SPECIAL PRICING True RMS 4 1/2 Digit Multimeter M-7000 $135 .05% DC Accuracy .1% Resistance with Freq. Counter and deluxe case Function Generator Blox #9600 »?£.# $28.95 Provides sine, triangle, square wave from \Hz to 1MHz AM or FM capability nraoi 10 Function Multimeter CM-365 $65 AC t DC Voltage S Amps Resistance to 200nM£l Diode. Logic. A Trans lest Capacitance to 200uF Digital Capacitance Meter i mm- cm -1550 $58.95 9 Ranges .Tpl-20.000uld .5% basic accy Zero control with case Triple Power Supply XP-620 Assembled $65 Kit $45 21o 15V at 1A. -2to-15Vat1A (or 4 to 30V at 1 A| and SV at 3A Contains all the desired features for doing expetiments. Features short circuit protection, all supplies. iuV Digital LCR Meter LC-1801 $125 Measures; Coils 1uH-2t»H Caps .1pl-200ut Res .01-20M Wide Band Signal Generators „ SG-9000 $129 RF Freq 100K-450MHz AM Modulation ol 1KHz Variable RF output SG-9500 w Digital Display and 1 50MHz built-in Counter $249 < rx 36 AC Current Meter ST-1010 $69.95 1000 Amps Dalai Peak hold 6 Functions Deluxe Case *** Decode Blox f#9610 or #9620 $16.95 #961 Resistor Blox 47ohmto1M&100Kpot =9520 Capacitor Blox 47pl to 10MFD Quad Power Supply XP-580 $59.95 Fully regulated and short circuit protected xp-575 without meters {39.95 LEARN TO BUILD AND PROGRAM COMPUTERS WITH THIS KIT! INCLUDES: All Parti, Auwnbly and Louon Manual Model MM-800Q $129.00 Digital Triple Power Supply XP-765 $249 0-20V at 1A 0-20V at 1A 5V at 5A Fuly regulated. Short circuit protected with 2 limit control, 3 separate supplies XP-660 with Analog Meters $175 GF-fl0 16 Function Generator with Freq. Counter $249 Sine, Square, Triangta Pulse, Ramp, .2to2MHi Freq Counter .1 - 10MHz GF-8015 without Freq. Meter $179 Starting tram scratch you buifcl a complete system. Our Micro-Master trainer teaches ycu to write into FWMs , ROMs and run a 8085 m icrcprocos- sor, which uses similar machine language as IBM PC. You will write the initial' instructions to toll the 6085 processor to net started and store those instructions in permanent memory En a 2816 !i PROM. Teaches you all about input and output ports, computer timers. Build your own keyboard and learn how to scan keyboard and display. No previous computer knowledge required. Simple easy to understand instruction teaches you to write in machine language. ROBOTICS KIT FOR ABOVE (MM-ftOID) 571 .9S WE WILL NOT BE UNDERSOLD! Q £ C SALES INC 15 Day Mone V Back Guarantee UPS Shipping: 48 states 5%f— fe^g. 1245 Rosewood. Deerfield, 1L 6001*5 2 Year Warranty *<* ^ to ck** ($10 Max) IL Res., 7% Tax CfTjgjBJ (gnQ) 292-7711 (708) 541-0710 WRITE FOR FREE CATALOG CIHCLE 109 ON FHEE INFORMATION CARD TURN YOUR PC INTO A UNIVERSAL FREQUENCE COUNTER^ Build a frequency-counter boar that operates in a Windows environment in your personal computer. JOEY GRASTY and BILL SCHULZ FREQUENCY COUNTERS i IAVE I OMK A long way since Hewlett Packard introduced the 524A back in 1952, It was a huge instrument, containing more than 70 vac- uum tubes, but it could measure Frequencies up to 10 megahertz, and time intervals as small as 100 nanoseconds, in late 1988, a proj- ect began to reduce the major parts of a universal frequency counter into a single integrated circuit, which greatly increased the performance and measure- ment capability of frequency counters built with this new IC. The project culminated with the OE10, an IC thai could directly measure frequency up to 240 MHz and measure time intervals with resolution to 0.1 nanose- conds. The OE10 was then incor- porated into the PC10. a high- performance universal frequen- cy-counter board for IB M PC XT AT and compatibles — and now you can build it yourself. The combination of a PC and a frequency counter produces a powerful tool useful for a wide range of measurements. Not only does the PC10 contain most of the features of more expensive laboratory benchtop frequency counters at a fraction of the cost. ii also has many functions that no bench counter can match. The PC10 operates in Microsoft Windows, which allow the user to lake measurements while per- forming other tasks. The Win- dows environment also allows data to be shared Willi other pro- grams. Data logging and auto- matic software calibration of the timebase are also provided. Fi- nally, the PGlOcan directly tune a receiver to the measured fre- quency using the computer's se- rial port. However, before we discuss how the PC10 operates and how you can build one for yourself. lets first talk about how univer- sal frequency counters work. Frequency measurements A frequency measurement is defined as a number of cycles of an incoming signal occurring during a given time period. The unit of frequency is Hertz (Hz), or cycles per second (cpsl. A fre- quency measurement Is per- lormed by counting the number of cycles occurring within a spe- cific gate time, which typically ranges from 0.01-10 seconds, ni more. The OE 10 has lour built-in gates— 0.01. 0.1, J.O and 10 sec- onds — as well as programmable gate limes than can be set from less than a microsecond to more than 28 seconds. The gale time, along with the timebase os- cillator frequency ( 10.000 MHz), determines the resolution of the frequency measurement, or the number of significant digits thai can be displayed. A frequency measurement may also be presented — that is. before the signal to be measured enters the frequency counter, it is divid- ed by an Integer number. Prescal- illows signals to be measured that are higher in frequency than i tie counter is normally capable of measuring. The OE10 sup- ports three prescaler values: 4. 16. and 64. However, prescaling requires that the gate time must be multiplied by the prescale to ■n m cc II C > 37 TESTOUT -*(- TEST — MBwM .-!■-- ... ■* ilfa 28-BIT TERMINAL (GATE) COUNTER [BINARY) .DATA NTROLBLIS C_I:^_'_ : __^_-„ CRYSTAL OSCILLATOR WD CONVERTER CONTROL FOR BARGRAPH V' ' -v'l 2 LIQUID CRYSTAL DISPLAY INTERFACE gp ^ ©s fe 2fcfiS» -*- XTAL2 XTAL1 ADCS- ADCLK ADDATA . SDA SCL BATTLOW LCDTEST FIG. 1— BLOCK DIAGRAM of the OEtO gate array. The device is packaged in a 44-pin plastic leaded chip carrier. O z O 39 o in _i HI g < 40 FIG. 2— THE PC10 INTERFACE is an 8-bit industry standard architecture {ISA) bus used in IBM personal computers and compatibles. used for the measurement. Bit D1SPTEST controls the display test, which is not used in the mi- croprocessor mode. Bit TSOURCE determines whether built in or programmable gates are used. Bit EXTGATE is used only for manufacturing test. Register CLRCNT provides a simple way to clear both the main counter and the terminal coun- ter. A write of any value to this location clears both counters. Likewise, writing any value to lo- cation STARTM starts a mea- surement cycle. To perform a measurement, clear both counters by writing to location CLRCNT. Next, program CREG1 and CREG2 for the prop- er type of measurement, gate time, and input source. If pro- grammable gate times are re- quired, program the terminal counter to the required value. Fi- nally, start the measurement by writing to location STARTM. The end of the measurement cycle can be monitored by polling MCOMR the measurement com- plete pin. The OE10 has four signal in- puts: A, B, C, and D. A and B can be used for all types of measure- ments, with the exception that input A is the only input that can be used for prescaled frequency measurements; frequency and period measurements require only one input, and use inputs A and B only. Time-interval and ratio measurements require two inputs, A/B or C/D. Inputs C and D are used only for time-interval and ratio measurements. The OE10 has two counters, the main counter and the termi- nal (or gate) counter. The main counter, which is a 36-bit binary- coded decimal (BCD) counter, is used to collect the measurement data. It is driven by a 5-bit Johnson counter that divides the incoming signal by. 10. The ter- minal counter is a 28-bit binary counter that generates gate sig- nals for a frequency or ratio mea- surement, or provides an average count for period or time interval measurements. The PC 10 interface, shown in Fig. 2, is an 8-bit industry stan- dard architecture (ISA) bus used in IBM personal computers and compatibles (but not PS/2 com- puters). The PC 10 is controlled by the PC through 32 input/output (I/O) ports. Since the PC decodes only the bottom 10 bits of the I/O address, the base address of the board is set by the four DIP switches (SI). The PC 10 decode logic consists of a programmable array logic (PAL) device, IC4, a 74LS86 quad xor gate, IC22, four pull-up resistors R3— R6, and a 4-position DIP switch, SI. The 20L8 PAL decodes the I/O ad- dresses into signals that enable PC10 PARTS LIST All resistors are Vi-watt, 5%, un- less otherwise noted R1— 2200 ohms R2 — not used R3-R6. R21— 10,000 ohms, '/s watt R7, R10— 4990 ohms, 1% R8, R9— 10,000 ohms, 1% R11-R1 4— 20,000 ohms, 1% R15, R16, R21— 10,000 ohms, 'A watt R17. R30— 75,000 ohms, Va watt R18. R20— 1000 ohms, 'A watt R1 9— 33,000 ohms, Vfe watt R22, R23— 75 ohms, chip resistor R24 — 91 ohms, chip resistor R25-R28— 1000 ohms, chip resistor R29 — 47 ohms, chip resistor R31— 100,00Q-ohm potentiometer C1, C3, C4— 10 iaF, 25 volts, radial electrolytic C2— 22 n.F, 25 volts, radial elec- trolytic C5-C33 — 0.1 (j.F, 50 volts, monolithic C34, C36— 330 pF, NPO C35— 47 pF, NPO C37. C38—8.2 pF, NPO 039— 2-7 pF NPO trimmer C40-C53, C67— 0.001 ^F, 1206 chip capacitor C54-C56, C58-C64, 068—0,1 |xF, 1206 chip capacitor C57— 330 fj.F. 16 volts, radial elec- trolytic C65— not used Semiconductors 101— 74HCT245 octal tristate transceiver IC2, IC3— 74HCT244 octal tristate buffer IC4 — 20L8 programmable array logic (PAL) 1C5 — OE10 application-specific inte- grated circuit (ASIC) IC6, IC8, IC14, Ic15— not used XXX IC7— 74HCT125 tristate quad buffer IC9, 1010— 74HC374 tristate octal D- type flip-flop IC11— AD7528 dual 8-bit multiplying digital-to-analog converter (DAC) IC12— TL074 quad op-amp 1013— AD580 voltage reference IC16-IC18— 74AC11151 eight-to-one multiplexer IC19— 74HCT74 D-type flip-flop IC20— 74HC00 quad NAND gate 1021— 74HC157 quad two-input multiplexer different devices on the PC10 board. The address bus and vari- ous control signals from the PC are buffered by two 74LS244 buffers, IC2 and IC3. Data buffer- ing is performed by IC1, a 74LS245 octal transceiver. Although the OE10 contains a crystal oscillator, much better performance can be obtained by using a temperature-compen- sated crystal oscillator as the timebase clock. The 10-MHz crys- IC22— 74LS86 quad XOR gate IC23— 74ALS12 triple 3-input NAND gate IC24— LM339 quad voltage comparator IC25, SC26, IC29— MAR6 MMIC IC27— UPB582C high-performance divide-by-four prescaler 1C28—CA3199E general-purpose di- vide-by-four prescaler D1, D2— HSMP3800 surface-mount pin diode Q1-Q3— 2N2907 PNP transistor 04, 05— PN2369 NPN transistor Other components J1— BNC bulkhead (R141-306) J2— SMB right-angle PC board connector {R1 14-665) RY1-RY3— SPOT DIP reed relay, 5- volt coil, form 1C LI-L3— 100 m-H choke P2— female DB25 connector (ITT DBU-25S-AA) P3— SMB plug, cable (R114-082) S1 — 4-position DIP switch XTAL1— 10-MHz crystal Miscellaneous: seven 14-pin IC sockets, four 16-pin IC sockets, six 20-pin IC sockets, one 24-pin IC socket (0.3-inches), one PLCC 44- pin IC socket, one Q57 modified stamped PC bracket (Globe Mfg.), one lug (Zierick #334), 6-inch 50- ohm coaxial cable RG187 (0.1 -inch diameter), PC board, solder, etc. Note: The following items are available from Optoelectronics Inc., 5821 N.E. 14th Ave., Ft. Lauderdale, FL 33334 (800) 327-5912, in Florida (305) 771-2050, FAX (305) 771-2052: Complete Kit of all parts to build the PC10, including software, $299; OE10 ASIC, S49; PC10 PC board, $59; software, $5; pro- grammed PAL, $19; assembled and tested PC10, $339; complete kit of allparts to build the API OH, $179; AP10H PC board, S39; ma- chined and painted cabinet, $49; 6-foot 25-conductor straight- through cable, $20; assembled and tested AP10H, $229. Send SASE for priced out parts list. Include 5% shipping and 6% sales tax when shipped to Flori- da address. tal. XTAL1, controls the frequen- cy of oscillation; the frequency may be set precisely using trim- capacitor C39. That's all we have room for, so we'll have to finish up this story next month. We will then finish up the discussion on the PC 10 g) circuitry, we'll talk about the op- g tional external amplifier board, > the AP10H, and we'll show you < what is involved in building both ^ of them. 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FAX: 516-293-3315 A PICTURE IS WORTH A THOUSAND words — especially when you're trying to determine the frequen- cy response of an audio amplifier or filter design. Our sweep/mark- er generator lets you create an os- cilloscope display that shows the response of an of an audio sys- tem. It can be a useful tool for designing and analyzing ampli- fier and filter circuits. With the sweep/generator, the user programs a desired frequen- cy range that is swept into the input of the device under lest. The response curve of the fre- quency sensitive circuit is dis- played on the scope screen. When using a conventional storage scope, multiple response curves can be superim- posed for a helpful com parison of waveform characteristics. The sweep/gener- ator can be used to examine the tuning response of an am- plifier, check cir- cuit stability or even be used by acoustic engi- neers. Let's take a closer look into the operation of this ver- satile unit. Operating features The sweep/generator operates in two basic modes: read or run. In the read mode, the frequency sweep range can be programmed by adjusting the start and stop multi-turn potentiometers on the front panel. Three user ad- justable frequency ranges can be swept into the device under test— 3 Hz to 1000 Hz. 35 Hz to 20 kHz. and 3 kHz to 100 kHz. The user adjusts the exact beginning and end of the frequency range to be swept. While in the run mode, each of the frequency ranges may be swept in its entirety, or any portion of the range, as low as 0.4%, may be swept. The upper 100-kHz frequency range may have up to 12% error over the en- lire band, the amount of error is roughly reduced in proportion to the amount of the band being swept. There is also a sweep rate potentiometer, which can be ad- justed from 50 milliseconds to 30 seconds per ten graticule divi- sions in each of the three fre- quency ranges. The sweep output provides a sawtooth ramp for the X input to an oscilloscope. The frequency range that is being swept uses five markers, or brightened spots, equally spaced at 25% intervals along the hori- zontal graticules. The first and fifth markers are adjusted to the outer most graticule lines. The frequency at each graticule line can then be determined by tak- ing the difference between the AUDIO _ SWEEP/MARKER GENERATOR -*■ Ao • — ~t JOHN WANNAMAKER Build this sweep/marker generator and dis- cover the audio- range frequency response of your amplifier or filter design. start and stop frequencies and dividing by ten. All markers are indicated on the front panel LED's. Figure 1 shows a swept sine output of the sweep/gener- ator displaying such markers at 25% intervals along the horizon- tal graticule lines. When you are in the run mode, the markers should be turned off when sweeping. A momentary overshoot could occur that is not actually present ff the marker switch was on during sweeping. That effect is less likely to happen at higher frequencies. The amplitude level of the swept sine-wave output may be varied from 10 millivolts to 5 volts peak-to-peak by the sine level control. The output impedance is about 700 ohms, and the output level is maintained within 0.5 dB from 10 Hz to 100 kHz. Two on-board trimmer potentiometers al- low adjustment of the sine shape to as little as 0.5% total harmonic dis- tortion. The very act of sweeping gener- ates its own type of distortion, which can be minimized by using a long-duration sweep. Another feature of the read mode is its capability to move between the five markers and cursor with the skip button, and stay at a posi- tion with the hold button. When held at a particular position, the frequency of that marker or cur- sor can be read on the front panel display. The initial display is dim, when it brightens after a few sec- onds you'll have an accurate fre- quency reading. The cursor is an additional marker which can be adjusted to a particular point of interest while In the run mode. The user can move the cursor marker with the cursor potentiometer to any point on the swept frequency. The cursor is best used to deter- mine the frequency of a point be- fore going to the memory mode. The cursor frequency is read in the read mode the same way as the marker frequency is read. Input and output jacks are lo- cated on the front panel for con- nection to an audio amplifier or m m jj c > I 43 o z o a. LU g < tr FIG. 1— THE AUDIO OUTPUT SINE wave of the sweep/generator shows five equally spaced markers. filter device and an oscilloscope. A conventional, digital memory or storage scope may be used with the sweep/generator, how- ever the connections are dif- ferent. Figure 2 shows 'a basic connecting diagram that can be used with a conventional scope. The swept sine output connects to the audio input jack, the audio output jack connects to the peak- hold input jack of the sweep/gen- erator. The sweep output and peak-hold outputs of the sweep/ generator connect to channels X and Y of the scope, respectively. The scope must be used in the X- SWEEP SINE SWEEP/MARKER OUT GEN - IN PEAK HOLD OSCILLOSCOPE OX Or FIG. 2— A CONNECTING diagram shows how the sweep/generator can be used with a conventional scope. Y mode for a proper display. Conventional analog storage scopes are best suited for use with the sweep/generator. When that type of scope is used, the sweep output connects to the scope's external trigger. Some digital-memory scopes, unfor- tunately, do not have the memory capability when used in the X— Y mode, nor can they remember superimposed sweeps of dif- ferent shapes. To use the storage mode of a digital-memory scope, the sweep/generator must be synchronized with the scope's in- ternal sweep, and the sweep rates must be adjusted for similar times. When a digital-memory scope is used, the sync output of the sweep/generator connects to the external trigger of the scope. The dual-trace feature of a dig- ital-memory scope must be used in order to achieve a suitable dis- play. Those various connections are shown in the side bar under Operating Instructions. A peak-hold circuit is incorpo- rated in the sweep/generator to create a clear base line reference of the frequency response curve. The output signal from the prod- uct to be tested may be fed di- rectly into the scopes Y input, but there will be no well-defined base line because of the mirror- image of the audio response. The peak-hold circuit overcomes that problem by momentarily holding the peak value of each positive alternation of the signal, and then quickly reducing to zero. The output from the tested device is connected to the peak-hold in- put, the peak-hold output is then connected to the scopes Y input. The scope will display a contour line that follows the positive "en- velope" of the response curve. That rather nice feature has a nearly flat frequency response from 20 Hz to 20 kHz (within 0.25 dB) and can be used up to 50 kHz. The input to the peak-hold cir- cuit should not exceed 3.5 volts peak-to-peak. The circuit works adequately with an input as low SWEEP T1ME= 1 SECOND \ SWEEP TIME= 30 SECONDS NOTCH MISPLACED BY - 2Hl 62Hz RETRACED 80Hz NOTCH SHOWS 97Hz CIRCUIT 108Hz STABILITY 10HzT01010Hz EXPANDED VIEW 10Hz TO 210Hz FIG. 3— FILTER RESPONSES: (a) shows a 60-Hz notch filter, a smooth response Is displayed with a slow sweep of 30 sec- onds, a faster sweep of 1 second gives overshoots and misplaces the notch by almost 2 Hz; (b) shows a 180-Hz notch filter with selectable low-end gains, note the same notch is retraced, indicating cir- cuit stability; and (c) shows a low-end re- sponse of an amplifier with a 180 Hz notch filter, one trace covers a 10- to 1010-Hz range, the expanded view covers a 10- to 210-Hz range. CURSOR FIG. 4— PEAK-HOLD CIRCUIT not in use, note how the mirror image is displayed: (a) shows an L-C tuned circuit, the fre- quency sweep is 50 kHz at 5 kHz per divi- sion, with the cursou marker at the curve peak, 52.48 kHz; (b) shows an audio ampli- fier frequency response from 20 Hz to 120 Hz. as 35 millivolts peak-to-peak, but any value below 20 millivolts peak-to-peak will come out as a base-line value of about +5 milli- volts peak-to-peak. Now that we've introduced you to some of the operating features of the sweep/generator, let's ex- amine some of the scope displays it can produce. Sweep/generator uses An example of the sweep/gener- ator being used to determine the frequency response of a notch fil- ter is shown in Fig. 3-a. The ad- vantage of a slow sweep with its inherent little distortion of the sine wave is seen in the two su- perimposed sweeps. The smoothest response is at a sweep time of 30 seconds. The faster sweep of 1 second shows over- shoots and a displacement of the notch frequency that are not present at the slower sweep rate. Two interesting displays are shown in Figs. 3-5 and -c. Figure 3-b shows five superimposed re- sponse curves of a 180-Hz notch filter with variable low-end gains SWEEP SINE SWEEP/MARKER GEN. 0UT PEAK HOLD IN LINEAR AMP. 1 OUT INI IN OUT AUDIO AMP. Ji SPKR MIC FIG. 5— THE SWEEP/GENERATOR CAN BE USED as a tool in testing the acoustic re- sponse of a room. The amplified swept sine wave is projected into a room, and is picked up by a microphone, whose signals are then amplified with a linear amp and fed into the peak- ho Id circuit. selected at 62 Hz, 80-Hz, 97 Hz, 108 Hz and 135 Hz. The filter's stability is illustrated by retrac- ing the same notch at the various frequencies. Figure 3-c shows a low-end response of an amplifier with a 180-Hz notch filter. One trace ranges over a frequency of 10 Hz to 1010 Hz, the other trace is an expanded view with a fre- quency range of 10 Hz to 210 Hz. Figure 4-a shows the use of a cursor in an L-C circuit. The total T — — - ....... ■:j 1 ,. 'p , | r - J | : 1 r ^'-$' ■ f ■ ■: L - --_, ■ X : "hA_'i' .... WB9 ,, i ■jjH "" " ■ * B ' 1 HJ J 1 FIG. 6— SCOPE DISPLAYS show an acoustic response of a room: (a) shows a line-contour display where the top is swept over 1 kHz to 3 kHz, the bottom is swept over 45 Hz to 5045 Hz; (b) shows a filled-in display which is achieved by in- creasing the scope's intensity. frequency sweep is 50 kHz, at 5 kHz per CRT graticule division. The cursor marker, at 52.5 kHz, is at the peak of the curve. Figure 4-5 shows an audio am- plifiers frequency response from 20 to 120 Hz. The mirror image of the response curve is displayed in both Figs. 4-a and -b because the peak-hold circuit is not in use. An unusual application of the sweep/generator is in the field of acoustic engineering. The gener- ator can be used as an aid in acoustic design by amplifying a swept sine wave into a speaker, and projecting that sound into a room, or perhaps an auditorium. The acoustic response of the room is picked up by a micro- phone, whose signals are fed into a linear amplifier. The output of the linear amplifier is connected into the peak-hold circuit of the sweep/generator. A block di- agram showing the connections for an acoustic response arrange- ment is shown in Fig. 5. A high quality linear amplifier should be used to pick up microphone sig- nals. Also, the frequency re- sponse of the audio amplifier and speaker should be known to avoid misinterpretation of the amplifier response with that of the acoustic response of the room. Figure 6-a shows a line con- tour-display of an acoustic re- sponse of a room with the peak- hold circuit in use. The upper display is swept over a frequency range of 1 kHz to 3 kHz {200 Hz per graticule division), while the tower display varies over a 45 Hz to 5045 Hz range (500 Hz per m CD D c > DO < 45 All resistors are Vi-watt, 5%, un- less otherwise indicated. R1— 3900 ohms R2, R5, R15. R19. R24, R25, R26, R39, R41, R58. R59, R77, R99— 10,000 ohms R3, R47— 3300 ohms R4, R28, R31— 50,000-ohm potenti- ometer R6— 10,000-ohm multiturn potenti- ometer «R7— 2000-ohm 10-turn potentiome- ter R8— 2200 ohms R9 — 2000-ohm multiturn potentiom- eter R10— 6800 ohms R11— 10,000-ohm 10-turn potentiom- eter R12, R13— 1 megohm, 1% R14, R1 7^7,000 ohms, 1% R16— 5000-ohm multiturn potenti- ometer R18, R80, R90— 100,000 ohms R20, R79— 1000 ohms R21, R23— -10,000-ohm potentiome- ter R22— 12,000 ohms R27 — 500-ohm potentiometer R29, R32, R33, R36, R49, R54, R56, R67-R71. R92, R102, R1 03— 4700 ohms R30, R34, R38, R48, R50, R51. R53, R73, R76, R78, R81, R82— 47,000 ohms R35, R40— 68,000 ohms R37— 15,000 ohms R42 — 1 .5 megohms R43, R83, R87— 150 ohms R44, R46, R91, R100, R1 01— 1500 ohms R45 — 50,000-ohm potentiometer with SPST switch R52— 270,000 ohms R55 — 4.7 megohms R60-R66, R94, R95— 100 ohms R72— 68 ohms R74 — 1 megohm R75— 10 megohms PARTS LIST R85, R86— 10 ohms R84, R87-R89— unused R93, R97-^.7ohms R98— 330 ohms Capacitors C1, C2, C17. C26, C29, C32, C66, C68, C69— 10 jiF, 25 volts, elec- trolytic C3, C6, C7, C15, C30. C31, G36, C37, C65, C91, C94— 0.001 jiF, Mylar C5, C9, C11, C14, C23, C28, C33, C61— 0.01 ixF, Mylar C4, C13, CI 6, C25. C60, C73, C74. C75— 0.1 nF Mylar C8, C64— 22 pF, ceramic disc C10 — 470 pF, ceramic disc C12, C39-C59. C76-C89— unused C18— 100 p.F, electrolytic C19— .0068 |j.F, Mylar C20— 0.004 txF (four 0.001 |xF 1% capacitors in parallel), Mylar C21— 0.8 |j.F (0,33jxF and QA7\x.F wired in parallel), Mylar C22— 0.033 |4.F, Mylar C24, C27, C35— 0,005 |xF, Mylar C34, C38, C62, C67— 47 nF, 16 volts, electrolytic C63, C95— 100 pF, ceramic disc C70— 3300 |iF, 25 volts, electrolytic C71, C72— 1000 u.F, 25 volts, elec- trolytic C90— 10 fj.F nonpolar, electrolytic C92-^70 jjlF 16 volts, electrolytic C93— see text C95 — 47 pF, ceramic disc C96— 0.05 jaF, Mylar C97— 2200 m-F, electrolytic Semiconductors IC1, IC14, IC15— XRL555 timer IC2— CD4040, 12-stage binary ripple counter IC3— DAC1222LCN D/A converter IC4, IC6. IC7, IC8, IC9, IC23-IC25— CA3140E op-amp IC5— LM336Z 2.5-volt reference di- ode IC10, IC26— CA3130E op-amp IC11— CD4068 8-input nand gate IC12 — CD4538BCN/BCP or MM14538BCM dual-precision monostable multivibrator IC13— CD4017 decade counter/di- vider IC16— XR2206 monolithic function generator IC17, IC18— RDD104 timebase IC19— 74C926 counter IC20— 7812 12-volt positive regulator IC21— 7912 12-volt negative reg- ulator IC22— 7805, 5-volt positive regulator Q1-Q13— 2N4401 transistor Q14— 2N2219 transistor or VN0300M MOSFET (see text) D1-D7— 1N914 diode D8, D9, D10— 1N4001 diode DSP1— NSB3881 , 4-digit, 7-segment LED display LED1-7— LN28CAL(US) Panasonic high-efficiency light emitting di- odes Other components Si, S2 — momentary contact push- button switch, SPST S3— ON-OFF-ON toggle switch, SPDT S4 — SPST switch mounted on R45 S5— 3PDT toggle switch S6 — 3- pole, 4-position rotary switch S7— SPST toggle switch, 1.0 amp, 125 volts AC T1— 120 volts primary, 12.6 volts sec- ondary, 0.6 amps J1^J6 — RCA chassis mount phono jacks XTAL1— 5-MHz crystal F1 — 0.5-amp fuse Miscellaneous: Fuseholder, 3-con- ductor 18 AWG line cord, Jameco enclosure type H2507, DIP sock- ets and hardware. Note: A set of 2 PC boards is avail- able from John Wannamaker, Route 4, Box 550, Orangeburg, S.C. 29115: $43.00, postage paid, S.C. residents add 5% sales tax. graticule division). An alternate filled- in display is shown in Fig. 6-fc>. The area un- der the response curve is filled- in, rather than having only a base line and contour line. A filled-in display can be achieved cj by increasing the intensity level z on the scope. The main disad- cr vantage of that type of display is o its inability to display multiple j traces. o Q < EC Theory of operation Two PC boards are used in the sweep/generator: a main board, consisting of a function gener- ator, counter, and analog-to-dig- ital conversion circuitry, and a power supply board, which also includes the peak-hold circuit. A schematic of the main PC board is shown in Fig. 7. On this board, an XR2206 function generator chip, IC16, is used as a current- controlled oscillator. A low-to- high frequency sweep occurs when current flow from ground into pin 7 varies from near zero to about 3 milliamps. That current change takes place when a dig- itized ramp, or sweep voltage, is applied to the base of Ql. The ramp voltage is created by applying pulses from an astable multivibrator, IC1, into a 12- stage binary counter, IC2. The re- sulting binary-coded outputs are converted into an analog voltage by a 12-bit digital-to-analog con- verter, IC3. The output of the con- verter at pin 1 must feed into the virtual ground of op-amp IC4. The output of IC4 has an appar- ent straight-line voltage rise, but 46 _™n F Hhold Jf v - V + 12V «'3- R57 15K R44 B4S 1.5K 5DK MARK WIDTH IC7 CA3140E FIG. 7— THE MAIN BOARD SCHEMATIC; IC16 IS USED AS a current-controlled os- j, cillator— a frequency sweep is generated when current flow from ground to pin 7 varies "•* from to 3 milliamps. IC5 is a 2.5-volt precision voltage regulator used to minimize DISP1 TSB3881 R71 4.7K R62 100Q 'l>l l_l !_' I—' LJ M.M M R63 1G0O Q3 2N4401 rO to R67 7K +■ SHAFT ' -9 S6-b T0S6-a~l ,--"1 ° SINE l*" RANGE S6-C HIGH o ft 120VAC •1 T1 J> 12.6VAC L-ct o — -a\S> — -JIAMAj- 1 S7 F1 = .5A KTUW^n -VA- R86 1K1 R68 4.7K 2H4401 R69 - 11 ' 4.7K: ■VA-f R73 D5 «™ IN 9 M — M IC19 74C926 10 15 16 17 18 13 C61 .01 -K- LED7 LN28CAL & R76 47K 5 |6 R74 1MEG C60 .1 06 --1H914 ^ R78 4/K R79 179 .J 1K :• C62 47jiF 08 2N4401 09 2N4401 €v vL; C65 .001 c i, R80 3-100K IC18 RDD1D4 C66 10uF' IC17 RDD1D4 D10 1N4001 IC22 7805 C72 "p100Q{iE R85 ion C69 10(iF 7* C74^ .1 09 1N40B1 — K— C71 IOOOuFT X * W v R81 47K .1* R75 10MEG XTAL1=t: 5MHz ^ C64 J. 22pF D7 1N914 D8 1N4001 W R87 1S0Q C70 3300nF IC21 791 2 IC20 7812 A. CSS T 1 ^ + 12V _T -L C67 47mF -12V R83 1S0O -Wr- 01 2H4401 re R82 47K BRIGHTER o- FIG. 8— THE COUNTER AND POWER-SUPPLY BOARD SCHEMATIC; The lime-base for the counter originates from IC17 and IC18. A 5-MHz crystal oscillator is used by IC17 and is programmed via pins 1 and 2. The output of IC18 is a square wave which provides a 0.1 or 1 second sampling of the frequency to be measured by the shorting or non-shorting action of Q8. o z o F o hi o < DC in reality it is composed of 4,096 small steps. When the frequency of IC1 changes, the ramp's slope and duration change. Two inverting unity- gain op- amps, IC6 and 1C7, provide level- shifting controls for adjusting both ends of the ramp. That per- mits adjustable start and stop points as well as some limit-set- ting to protect IC16. Op-amp IC8 and transistor Ql act as a voltage- to-current con- verter for the most linear control over the frequency of the IC16. Frequency drift is a problem, es- pecially within the true audio range, which is at the low end of the middle range. When a device operates in the audio range, a 1- millivolt drift can cause a change of 18 Hz. To minimize frequency drift, a 2.5 volt precision voltage regulator, IC5, is used, and after one hour of warmup time, the 48 drift averages about 5 or 6 Hz per hour. An 8-input nand gate, IC11, provides a falling edge output at 25% increments as the ramp is taking shape. That falling voltage triggers IC12-a, a one-shot mono- stable multivibrator, which then applies a 10-millisecond input pulse to decade counter, IC13, which has one-of-ten decoded outputs. Each of the five counts light separate LED's to indicate which marker is in progress. The highlighted marker fre- quency is established by the technique described below. The pin 9 output of IC12-a triggers a one-shot monostable multi- vibrator, IC12-b. Its pulse width may be either fixed at 15 seconds or variable from 10 to 150 millise- conds depending on whether the unit is in the read or run mode. During the time that the voltage at pin 7 has dropped to zero, as ta- ble ICl's reset pin is held and cannot furnish pulses to the 12- stage counter. The counter holds whatever count exists at that time which ultimately translates into a steady control current at IC16, and a steady frequency out of it. The continuous frequency out of IC16 is the marker fre- quency. Each time the ramp stops, the sweep applied to the scope's X input holds a steady val- ue. That stops the trace in its tracks and the unmoving elec- tron beam creates a bright spot which is the marker. If there is a signal at the Y input, the marker becomes a brightened vertical line. The stop marker is generated on the count of 4,092. After its completion, four more counts re- turn the 12-stage counter to an all-zeros output condition, the ramp returns to its starting point, and a synchronized pulse is generated by transistor Q2. That same pulse resets IC13, the LED markers counter, and the voltage that had previously lit the stop LED falls to zero. That fall retriggers IC12-a and a new se- quence begins. The built-in counter that dis- plays the marker frequency can- not give a meaningful readout when it is in the run mode be- cause the frequency is con- tinually changing. A valid fre- quency readout can be displayed only in the read mode, where a IN 'M= + 12V1 .0R2N2219 (SEE TEXT) FIG. 9— A SCHEMATIC OF THE PEAK-HOLD CIRCUIT; IC23 AMPLIFIES the signal from the tested device, and reproduces only the positive alternation of the waveform. Tran- sistors Q13 and Q14 act as switches— when open, C93 charges to the peak value of the positive alternation, then holds the peak vatue. The top portion of that charge is one segment of the positive contour line. one-second sampling of an un- changing frequency can be taken, lb keep the user aware of that, the display is dimmed until the readout is valid. An accurate readout may not be available to the user until three seconds after stopping on a marker. A three- second delay is provided for all automatic stops before the dis- play is brightened. Integrated circuit IC14 is used as the one-shot, three-second de- lay for the automatic stops. A three-second delay is triggered every time the marker one-shot, IC12-b, is activated. The delayed falling edge out of IC14 at pin 3 triggers another one-shot, IC15, which produces a long duration "brighten" pulse to Q10 in the power supply. Once the brighten one-shot is triggered, it has the capacity to remain on for several minutes, but its time is cut short by IC12-b, which resets after 15 seconds. The hold pushbutton can extend this time if held pressed. The hold pushbutton also applies a positive voltage to the input of the 12-stage counter and prevents pulses from enter- ing. Timers IC14 and IC15 are type XRL555 made by Exar. Stan- dard 555 IC's do not work in this application. The cursor marker is gener- ated in a totally different manner from all other markers. A single op-amp, IC10, is used as a com- parator. A digitized ramp is ap- plied to the inverting input and an adjustable DC voltage from the cursor potentiometer is ap- plied to the non-inverting input. When the ramp rises to equal the DC voltage, the op-amps output falls to zero and actuates IC12-b to provide an added marker. The reason for the complexity of hav- ing two one shots to generate markers is that the cursor mark- er must be counted by all mark- ers, not just by IC13. The cursor marker must hold the astable IC1 reset for a period of time. The marker width control is a variable resistor with an at- tached switch, S4. When S4 is turned off, there are no markers, but the sweep will cover the same frequencies as if the markers were present. The frequency sweep for the middle range, or audio spectrum range, presents a problem for a four-digit counter display Reso- lution is poor at the low end if the readout is in kHz, and if the read- out is in Hz, the most significant digit would be missing on the high end. To overcome that prob- lem, the middle range occupies two positions on the sine range switch, and the user may select a readout in either hertz or kilo- hertz, m The counter and power-supply 5 circuit is shown in Fig. 8. The > timebase for the counter comes < from IC17 and IC18, both are - continued on page 70 5S 49 THE PURIST WILL TELL YOU THAT IF somethings worth doing at all, it's worth doing well- — and that's the case with the author of this story. The author always loved music, and was probably doomed to permanent audiophilia from day one. Even in 1960 at age 12, when he and his sister pooled re- sources to buy their first 45-RPM record (Pat Boone's "Love Letters in the Sand"), he recalls that, even on a monophonic, crystal- cartridge record player, there was an audible difference between the quality of a decent LP and the 45. Even though it should have sounded better than an LP the 45 was bassier, noisier, and some- what distorted, being pressed on what a broadcast engineer later poetically described as a blend of straw and chicken manure. Pre- dictably, he soon became dissat- isfied with the quality of the rec- ord player, and his junior-high and high-school years were marked by repeated attempts to upgrade the equipment without spending any money Along came the late '70's, and a new product was aimed at the pu- rists: beastie cables (the name has been changed to protect the author!), which are expensive heavy-gauge speaker cables. The old purism surged forward, re- membering the effects of cable re- sistance on damping factor and the effect of cable capacitance on high-frequency response — hut the ads also spoke of skin effect, 11 WW WILL DEASTIE SPEAKER CABLES IMPROVE YOUR AUDIO? which has to do with the fact that at high frequencies, alternating currents tend to travel mainly at the outside surface, or skin, of a conductor. Since the skin effect essentially removes current from the center of a conductor, effec- tively reducing it's cross-sec- tional area, it causes an increase in the impedance of a conductor at high frequencies. Actually, when frequency is high enough, a tube or pipe will have the same effective resis- tance as a wire of the same diam- eter. That fact can be used simplistically to account for the use of waveguides rather than wiring at microwave frequencies. But concerning high frequen- cies, how high is high? Supposedly, the skin effect be- comes important above about 30 MHz, but a recent ad for speaker cables claimed perceptible bene- fits from reducing skin effect at 20 kHz. Soon after, articles ap- w o z I IV _i UJ 6 S RICHARD A. HONEYCUTT 50 Are expensive speaker caile# really worth the money? This article tells how we foui peared in professional trade jour- nals mentioning the likes of Lu- casfilm using the enormous ca- bles, so some real research was in order. The goal was to find out whether beastie cables did in fact: • Reduce the amount of power lost in the cable enough to pro- vide a significant improvement in efficiency, or • Increase the damping factor of the speaker/amplifier system enough to provide audible im- provement, or • Provide any significant benefit in the frequency response of the system. No other benefits are claimed for these cables, so it is not neces- sary to look for undiscovered or presently unmeasurable effects. The problem was attacked both analytically and experimentally. The equivalent circuit of a real loudspeaker driven by a real am- plifier through real cables is shown in Fig. 1. Any effects pro- duced by the cables must show up in the cable resistance, capac- itance, or inductance. The effi- ciency and damping- fact or ques- tions depend almost exclusively upon the cable resistance, where- as the frequency-response ques- tion is mainly a function of the capacitance. Wire inductance is so small compared with the semi- inductive nature of speaker im- pedance at high frequencies that it can be ignored, as we will see. The cable resistance is made up of three components: the con- tact resistance, the ohmic resis- tance of the wire, and any contribution from skin effect. The ohmic resistance can easily be found from wire tables in most electronics reference books. Ta- ble 1 shows the resistance of a representative sampling of cop- per cables, listed according to gauge. For years, selection of ca- ble gauge has been made accord- ing to the criterion of 10% loss. In other words, for a given cable length, what resistance will give no more than 10% (0.46 dB) power loss at the speaker? Figure 2 shows the calculations involved in determining that value. For short cable runs, the resulting gauge is surprisingly small. About fifteen years ago when the author was an audio consul- tant, he would specify 18-gauge RESISTANCE, INDUCWICE. AND CAWCr TANCt Of CABLE FIG. 1— THIS CIRCUIT IS roughly equiv- alent to an amplifier, speaker, and length of cable. cable for amplifiers up to 100 watts feeding impedances of 8 ohms or more with runs of 25 feet or less. For each halving of im- pedance or doubling of amplifier power or distance, the wire size would increase by two gauges; 16 gauge for 100 watts into 8 ohms at 50 feet or 4 ohms at 25 feet, etc. That rule of thumb includes a safety factor so that the loss will always be less than 10%. The National Electrical Code specifies cable gauges based upon safety considerations: if a wire carries too much current over a long enough period of time, it can become dangerously hot and start a fire. Going back to the rule of thumb, a speaker with an average impedance of 8 ohms fed by a 100-watt amplifier will draw about 3.5 amperes at full power. However, even running at full tilt, it's unlikely that the aver- age power will be greater than one-third of your amplifier's max- imum, so the rule of thumb pro- vides a large safety margin from a fire-prevention standpoint. The damping factor can be de- fined as the ratio of a speaker's impedance to the total resistance TABLE 1 RES1STANC > Gauge Resistance (ohms/foot) 0.000098 2 0.000156 4 0.000249 6 0.000395 8 0.000628 10 0.000999 12 0.00159 14 0.00253 16 0.00402 18 0.00639 Note: The wire must make a com- plete round trip, so there's 20 feet of wire in a 1 0-toot speaker cable. in series with the speaker. Since the simple loss calculation in Fig. 2 depends upon the combined re- sistance of the speaker and the cable, the resistive power loss will be related to the damping factor. Thus we can find a relationship between damping factor and low- frequency loss. In the Audio Cyclopedia Howard Tremaine es- tablished that there is no value in trying for a damping factor great- er than 20 4 . That is based on the fact that the speaker's voice-coil resistance appears in the circuit, and its value — typically 6 to 7.5 ohms for an 8-ohm speaker — sets a practical limit on the bene- fits of reducing other resistances. The effective damping factor is equal to: TOTAL CABLE RESISTANCE J W» SPEAKER IMPEDANCE 1. CABLE RESISTANCE = 0.1 x SPEAKER RESISTANCE 2. RESISTANCE PER FOOT - TOTAL CABLE RESISTANC E TWICE THE AMPLIFIER-TO-SPEAKER DISTANCE 3. SELECT GAUGE FROM TABLE 1 FIG. 2— HERE'S THE TRADITIONAL meth- od normally used to determine speaker- cable gauge by loss. _ ^speaker "voice coil + **amp + ^cable A stated amplifier damping fac- tor of 20 would represent a total resistance of 8 ohms divided by 20. or 0.4 ohms in series with the amplifier. That would give an effective damping factor of: 8ft 6ft + 0.4ft = 1.25 assuming a 6-ohm voice-coil re- sistance. With most amplifiers having output impedances on the order of 0.1 ohm or less, this would mean that the cable resis- tance could be . 3 ohms . The loss in dB corresponding to an 8-ohm speaker fed through a 0.3-ohm cable is: = 201og, I gft \_ 10 \fiO+nW~ ^ 8ft + 0.3ft m .32dB 3 c > That means that for an op- -< timum effective damping factor, j£ the resistive cable loss should be ^ 51 less than 0.32 dB. Just for com- parison purposes, a 1-dB cable loss, which would result from a 0.9-ohm cable resistance, would result in an effective damping factor of 1.14, which is not much lower than 1.25. As mentioned earlier, skin effect increases the effective im- pedance of a wire, and can be best explained by looking at Fig. 3. The skin depth of a conductor is the distance into that conduc- tor, measured from the outside surface, at which current density is 1/e times that at the surface. (The symbol e stands for the base of natural logarithms, and equals approximately 2.72.) For a direct current, the current densi- ty (amperes per unit cross-sec- tional area) is the same through- out the wire. For AC, the current density is less at the center of the wire and greater at the surface. At low frequencies, the skin depth (which depends on charac- teristics of the bulk conductor material) is usually greater than the radius of the conductor, which means that for all practical purposes the current density is the same throughout the con- ductor. Larger- diameter conduc- tors can exhibit measurable skin effect at relatively low frequen- cies, including audio frequen- cies. The simplest indicator of skin effect is the ratio R AC /R DC , where R AC is the resistance per unit length of a wire to alternating current of a certain frequency and R DC is the ohmic resistance per unit length. As long as R AC / Rpc equals 1 , skin effect is negli- When Rac/Rdc rises sig- OUTSIDE SURFACE OF CONDUCTOR gible. O z 1 W 2 Q < SKIN DEPTH CURRENT DENSITY HERE IN AMPERES PER SQUARE METER IS 'ft.TS TIMES THE CURRENT DENSITY AT THE CONDUCTOR SURFACE. FIG. 3— THE SKIN EFFECT increases the effective resistance of a wire. The skin depth is the distance into the conductor at which the current density is approximate- ly V3 of that at the surface. TABLE 2— MEASURED CHARACTERISTICS OF CABLES , Cable Type C L R* (pF/ft) (uH/ft) (ohms/ft) 22-ga. cheap 10.7 0.29 0.0178 18-ga. zip 14.0 0.28 0.007 20-ga. twist 18.0 0.36 0.0107 4-ga. < ;able 50.8 0.29 0.0007 16-ga "drop cord" 22.4 0.38 0.006 shielded "guitar cord 105.8 0.30 0.048 16-ga. zip 12.5 0.23 0.0127 *One- */ay resistance, not loop resistance; that includes the contact resistance of the terminations. nificantly above 1, skin effect may begin to matter. We say may, be- cause it only matters if the total resulting increase in cable resis- tance causes a perceptible effect in the reproduction. For a fre- quency of 15 kHz, R ac /Rdc equals 1.1 when a 15-gauge solid wire is used. Larger wires will ex- hibit a greater proportional in- crease in resistance as frequency increases. Of course, since the re- sistance of large wires is lower to begin with, the actual change in measured resistance may or may not matter. Stranded wire is extremely dif- ficult to analyze. Naturally, each strand has a certain surface area, so that all the strands connected in parallel would have a very large surface area. In actuality, though, much of the surfaces of the individual wires are in con- tact with each other, making the actual effective surface area vir- tually impossible to determine — unless the individual strands are insulated from each other, as in litz wire. At any rate, we can use solid wire as a worst case to ana- lyze, knowing that we'll really be using stranded wire that has less skin effect. The actual resistance, capaci- tance, and inductance of a cable are distributed evenly along its length. Telephone engineers found out long ago that, for anal- ysis purposes, a cable's R, C, and L can be lumped into a single component if certain conditions are met. The conditions depend upon the attenuation constant and length of the cable. The at- tenuation constant (a) is given by: __^_ is the angular frequency, or 2nf. The author does not like to lie awake nights solving equations like that, and tables of attenua- tion constant versus frequency are not generally available for the kinds of cables used for speaker leads. However, tables for 19- gauge pulp-insulated telephone cable indicate that a 3-kilometer cable section can be analyzed using the lumped-constant +3 +2 5 P "- - S3 .1 -3 -4 a 50 LEGEND K-GA. CHEAP GUITAR CORD 500 IK FREQUENCY (Hi) 18-GA.ZP 16-GA. ZIP 5K 10K 2W 4-GA. CABLE FIG. 4— A COMPUTER SOLUTION, or prediction, of the model in Fig. 1 yielded these results. The worst-case loss is well under 1 dB at 20 kHz. 52 method at 1 kHz with a total at- tenuation under 1 dB and a phase accuracy within 5 degrees. Although it may not be imme- diately obvious to the casual ob- server, attenuation constant is proportional to the square root of frequency, so that would mean that the same accuracy could be expected at 20 kHz if the length we re reduced by V20 kHz/1 kHz that works out to about 2100 feet. Since we rarely extend speaker cables anywhere near that far, we can safely use the lumped-constant method with no qualms. That's what was as- sumed in Fig. 1. Table 2 shows the types of ca- bles chosen for the analysis, along with their measured resis- tance, capacitance, and induc- tance. The values were measured using a Hewlett-Packard 4261 A LCR meter and a test frequency of 1 kHz. Instead of a speaker, a re- sistance of 7.9 ohms and an in- ductance of 6.3 microhenries were used in the calculations. In- stead of "real" beastie cables, we used ones that were on hand, in- cluding a very large (4-gauge) stranded cable. If those cables showed no measurable detri- mental effects on efficiency, damping-factor, or frequency re- sponse, then the alleged beastie benefits would turn out to be so- lutions to a nonexistent problem ! A computer solution of the cir- cuit of Fig. 1 yielded the results plotted in Fig. 4. A 10-foot length was assumed for each cable, and it included the effects of cable ca- pacitance and inductance, but not the skin effect. Notice that the worst-case loss was well un- der 1 dB at 20 kHz. Computer solutions without experimental verification are not 2 x o o I— D- 14 12 10 8 6 A 2 20 50 100 200 500 IK 2K 5K 10K 20K FIG FREQUENCY (Hz) 6— THE MEASURED IMPEDANCE CHARACTERISTICS of the test speaker. 20 50 LEGEND S2-GA. CHEAP GUITAR CORD 500 IK FREQUENCY |tta) UK SOK JB-GA. ZIP 16-GA.ZIP J-GA. CABLE FIG. 7— SEE HOW THE ACTUAL MEASURED CABLE LOSSES compare to the predicted losses of Fig. 4. always trustworthy so the actual response of the cables was mea- sured on the setup shown in Fig. 5. The impedance characteristic of the test speaker is shown in Fig, 6, Although the amplifier was flat within ±0.2 dB from 20 Hz to 20 kHz, the amplifier's cal- ibration curve was nevertheless subtracted from the measured results in order to provide max- imum accuracy. The test results are shown in Fig. 7. Initial results seem to indicate that virtually anything can be used to connect a speaker to an amplifier and, if the distance is short, no serious detriment to efficiency will result. Damping factor is degraded slightly when cables 'lighter than 18-gauge are used, as shown by the loss ex- ceeding 0.32 dB. But what will happen if longer cables are used? From previous measurements, ordinary Romex house-wiring ca- ble is found to have about the highest capacitance per foot of any common wire. With the fac- tors mentioned earlier that con- trol skin effect, it is also clear that small wires will not experience SPECTRUM ANALYZER DUMMY LOAD OR TEST SPEAKER FIG. 5— THIS TEST SETUP was used to measure the effects on an audio signal caused by speaker cables. 20 50 100 200 500 IK FREQUENCY {Hz} +3 + ? + 1 _1 *"T" - ■» -3 -4 2K 5K 10K 20K m CD C > FIG. 8— SIGNAL LOSS OF 40 FEET of 12-gauge Romex cable. 53 Earn Your B.S. Degree in ELECTRONICS or COMPUTERS By Studying at Home Grantham College of Engineering, now in our 41st year, is highly ex- perienced in "distance education" — teaching hy correspondence — through printed materials, computer materials, fax, and phone. No commuting to class. Study at your own pace, while continuing on your present job. Learn from easy-to- understand but complete and thorough lesson materials, with additional help from our instructors. Our Computer B.S. Degree Pro- gram includes courses in the BASIC, PASCAL, and C languages — as well Assembly Language, MS DOS, CADD, and more. Our Electronics B.S. Degree Pro- gram includes courses in Solid-State Circuit Analysis and Design, Control Systems, Robotics, Analog/ Digital Com- munications, and more. An important part of being pre- pared to move up is holding the right college degree, and the absolutely neces- sary part is knowing your field. Grantham can help you both ways — to learn more and to earn your degree in the process. Write or phone for our free catalog. Toll free, 1-800-955-2527, or see mailing address below. o z o _i w 6 5 < EC Accredited by the Accrediting Commission of the National Home Study Council GRANTHAM College of Engineering Grantham College Road Slidell, LA 70460 + 3 + 2 + 1 m "- 1 en _1 E£ -2 K NN N -3 NX -4 20 500 IK 2K 5K 10K 20K 50K FREQUENCY (Hz) INCLUDING SKIN EFFECT Ft. L, AND C ONLY FIG. 9— SIGNAL LOSS OF 100 FEET of 12-Gauge Romex cable. significant skin effect, and large ones will, but even a large per- centage change in a large wire's small resistance is of little con- sequence. Trying the Rac/^oc values for various cable diame- ters in conjunction with the com- puter analysis, 12-gauge solid wire is found to have about the worst skin effect of any cable. Therefore, if any type of speak- er cable could cause frequency- response problems, the high ca- pacitance and the skin effect of 12-gauge Romex should make it the ideal bad example. Another run was made using a 40-foot length of Romex, both into a dummy load and into the test speaker. In the graph of Fig. 8. we see a hefty V-z-dB droop at 20 kHz, compared to the response at 20 Hz. The overall signal loss and damping-factor degradation are less than those of the smaller ca- bles that are shown in Figure 8. due to the lower resistance of 12- gauge cable.) Since that still wasn't signifi- cant, a computer simulation of 100 feet of 12-gauge Romex was performed, with response run clear out to 50 kHz. The results are shown in Fig. 9. Here, at last, is something the beastie people can sink their teeth into! Anyone who can hear 50 kHz will find a full 4.5-dB drop resulting from the use of 100 feet of 12-gauge Romex — providing, of course, they're using an amplifier and speaker that can reproduce it. Of course, the skin effect is still only about half a dB, and effective damping is not degraded, so maybe they'd better drop those points from their ads. The results of that rather in- volved bit of research clearly indi- cate that ordinary speaker ca- bles, including the ones that any knowledgeable audiophile would sneer at. do not significantly de- grade frequency response. They vindicate the rule-of-thumb ad- vice (18-gauge for 100 watts, 25 feet, into 8 ohms) except for a slight degradation in damping factor; 1.21 with a 25-foot cable run. For optimum damping fac- tor, that rule should be changed to 18-gauge for 100 watts, 20 feet, into 8 ohms. Also, only 20-gauge. 22-gauge, and guitar-cord cables are a serious detriment to damp- ing factor. R-E we .. seeker of sonic Ynit're feme to me right pliier! %Kf^ Build A Negative Ion Generator LAST MONTH WE STARTED building our negative-ion generator. Let's now finish up the project. We were dis- cussing the flyback trans- former and what the vari- ous connections are used for. Pin 7 is used as ground, since it presents the highest resistance between itself and the flyback transformer output lead, which 3x39. 4is often quite short to avoid high-voltage breakdown, so be careful how much insula- tion you remove. The bot- tom of the voltage-tripler PC board, with D6, D8. and D10, and the attachment points of the ground wire and both high-voltage leads was shown in Fig. 5 in last month's article. Figure 6-a shows the top of the main PC board mounted in the case and held down with RTV, while Fig. 6-i> shows a drawn ex- ploded rendition, giving the same components with greater clarity and defini- tion, but adding the top of the voltage-tripler PC board, connecting leads, and emit- ter needle. The wire shown balanced on top of the emitter needle in Fig. 6-fa is the rotor for an ion motor discussed later. The foil pattern for the main PC board in the prototype differs from the one shown in this article, primarily due toTl mentioned in the parts list, which differs from the one used in the prototype. In the prototype, the resis- tances between the lower-voltage taps and the flyback transformer output lead were measured, and the tap corresponding to the highest resistance (about 100 ohms) was taken as the ground terminal, since it was electrically furthest from the output lead. The low-voltage taps generally have numbers stamped on the metal bracket surrounding the ferrite core, numbered clockwise. Build this negative ion generator and put some charge in your life. ANTHONY J. CARISTI WARNING!! This article deafs with and involves subject matter and the use of materials and substances that may be hazardous to health and life. Do not at- tempt to implement or use the information contained herein, unless you are experi- enced and skilled with respect to such subject matter, materials, and sub- stances. Neither the publisher nor the au- thor make any representation as for the completeness or the accuracy of the infor- mation contained herein, and disclaim any liability for damages or injuries, whether caused by or arising from the lack of completeness, inaccuracies of the in- formation, misintepretations of the direc- tions, misapplication of the information, or otherwise. In the prototype, the tap used as ground happened to be pin 7. Although almost any flyback would work in this project, use one from a small-screen black-and- white TV. It'll usually be smaller and have a better turns ratio, but make sure it's wired for positive out- put, and has an open ferrite core for the new feedback and bifilar primary wind- ings. Note the manufacturer, model, and chassis number of the TV you salvage it from, in case you need more information about it later. Either that, or go to any TV service store and buy a new one, but know the specifics about it in advance, includ- ing the maximum safe flyback transformer output winding voltage, and the number of turns in the flyback transformer bifilar primary and output wind- ings. If your flyback trans- former has a high-voltage diode attached to its output lead, remove it before adding the new feedback and bifilar primary wind- ings. Then use an ohm- meter to find the trans- former taps coming off of the flyback transformer out- put winding. One tap is the high-voltage common, orig- inally going to the TV chas- sis; use the highest resistance tap as ground. In the version shown here, which was used in the prototype, pins 1-3 are hid- den by the ferrite core, while pins 4—7 are shown. Figure 7 is a magnified view of the feedback and bifilar primary windings, showing how they're added; use 20—24 gauge enamel wire, for ease of handling and ad- m equate breakdown voltage. Use S Mylar tape to insulate both new > feedback and bifilar primary 5 windings from the ferrite core. ^ Start wi th the feedback winding, S 55 'Si O z o cc I- o 1U _l o o < wrapping a thin layer of tape around a clear part of the core where the feedback winding will go. Use nine inches of magnet wire, five inches for the turns themselves and two inches for each lead, and wind five close turns around the core. At the end of the fifth turn, form a U-loop about 4 inches long as a center tap, and then wind an additional five turns in the same direction, as shown. Secure the feedback winding with tape, mark the start of the feedback winding with a "1," the U-loop with a "2, "and the end with a "3," using masking tape; remember the direction of the feedback winding. The bifilar primary winding is next. Although you can wind both halves adjacent to one an- other, as shown in Fig. 7, the per- formance should improve if you superpose them, actually wind- ing one half on top of the other for optimal coupling. Twist two pieces of magnet wire together, with five turns spread along the entire length as a twisted pair, for close proximity between the two wires during the winding pro- cess. At one end of the twisted pair, mark one wire with a "4," and the other with a "5." Obviously, for the center tap in the feedback winding, if you break the wire segment making the loop at the point where it bends, there's no electrical effect on the feedback winding, pro- vided you route both segments of the loop (now two separate leads) to the same pad on the PC board. Thus, if you prefer, you can break the loop at the point of the bend. However, in the case of the bi- filar primary winding, you really should make an effort to super- pose both halves, one on top of the other. However, if you do that, you have to wind both halves in the same direction, and in that case, if you bend the enamel wire into a loop, you'll have to spread both ends after completing the first half, in order to retrace it on the second half. Thus, it's proba- bly easier in that case to phys- ically break the wire, and wind the second half separately. Start with those ends, and al- lowing four inches of lead length, wind six turns of twisted pair through and around the core in the same direction as the feed- PARTS LIST All resistors are !4-watt, 5%, unless otherwise noted. Rl — 1000 ohms, PC-board mounted po- tentiometer R2— 220 ohms R3, R4 — 560 ohms (the former for the astable-flyback transformer combina- tion, the latter optional for the battery- operated version) R5-R6— 200- and 40-megohm series high-voltage focus divider, RCA SK3868/DJV-1, used for an optional high-voitage range extender for a con- ventiona! high-impedance (10- rnegohm) voltmeter (see text) R7 — 2.7 megohms Capacitors C1— 1000 u.F, 25 volts, electrolytic C2— 100 fi.F, 16 volts, electrolytic C3-C8— 0.001 nF, 10 kilovolts, ceramic disc C9-^0,001 |j.F. 500 volts, ceramic disc, optional for aluminum can/neon bulb experiment (see text) Semiconductors D1, D2 — 1N4004 sil- icon diode D3, D4— 1N4148 silicon diode D5-D10— RCA SK3067/502 high-voitage diode, 12 kilovolts P1V LED1— light-emitting diode for the bat- tery-operated version Q1, Q2— TIP31B NFN transistor IC1— LM317T adjustable voltage regulator Other components Ft— 0.5-amp slow-blow fuse with holder NE1 — 120- volt AC neon-bulb assembly with 47-100K built-in series resistor for the plug-in version (Radio Shack 272-712) NE2— neon bulb, type NE2 (not the part number), optional for experiment (see text) S1— SPST toggle switch S2— SPST toggle switch T1 — 18-volt center-tapped transformer (Radio Shack 273-1515) T2 — standard TV flyback transformer (see text) Miscellaneous: Plastic case (7.5 x 4.25 x 2.25-inches, Radio Shack 270-224), enamel magnet wire, three- wire line cord, emitter needle (made from either straight pin or sewing nee- dle), RTV silicon rubber, heat sinks, four alkaline "D" cells (optional for battery operation), 2-liter plastic soda bottle, and a sewing needle. Note: The following are available from Anthony J. Caristi, 69 White Pond Road, Waldwick, NJ 07463; Two etched and drilled PC boards (one each for the main and voltage-tripler sections) for $15.95, IC1 for $3.25, Q1 and Q2 for $2.75 each. Please add $2,00 for postage and handling with each order; NJ residents please add 7% sales tax. FIG. 6— THE TOP OF THE MAIN PC BOARD, held down with RTV (a), and an exploded view (b), with D2, D4, and D6 not visible. You can see the new feedback and bifilar primary windings, with Mylar tape insulating them from the ferrite core. The enamel leads are "1"-"6," as in Fig. 1; "2" and "5" are paired. 56 back winding. The directions of both new feedback and bifilar primary windings must be cor- rect to achieve oscillation. Place the closely wound turns directly over the feedback winding, and secure the bifilar primary wind- ing to the core with plastic tape. Scrape away %-inch of enamel at the four ends of the bifilar pri- mary winding, and locate the un- marked end connected to wire "4" with an ohmmeter. That's the center tap of the bifilar primary winding, and is marked with a "5," using a piece of masking tape. The duplication is deliber- ate, and it'll be connected to the other "5" wire later; mark the re- maining wire with a "6," You can also see the new feed- back and bifilar primary wind- ings, and the Mylar tape insulat- ing them from the ferrite core. The enamel wires are numbered "l"-"6," as in Fig. 1; remember that "2" and "5" are paired. Lead "2" is really a loop in the feedback winding, with the enamel scraped off the end where it's bent and folds back, while "5" is really two separate wires from the bifilar primary winding. In Fig. 6, on flyback transformer T2, you can clearly see the low-voltage taps. Their corresponding num- bers are stamped on the metal frame of the ferrite core, increas- ing clockwise when facing the taps, so that pin 7, the ground, is at the lower right. Mount the flyback transformer to the main PC board with suit- able hardware. Using Figs. 1. 2, and 7 as a guide, connect the feedback and bifilar primary windings after cutting the leads and scraping the enamel. Re- member, there are two leads marked "2" and two marked "5," so don't mix them up. When finished, position the leads to avoid a short, and be sure the ROTOR ALUMINUM BRACKET POWER LINE CORD (120 VAC) m XI c > 5 57 y z o (T (- O UJ _i LU g Q < TYPICAL BASE WAVEFORM FEEDBACK WINDING i (ONE WINDING 1 WITH C.T LOOP) BIFIUW PHIMAHV WINDING (TWO SEPARATE! WINDINGS) FIG. 7— THE NEW FEEDBACK and bifilar primary windings, wound on the ferrite core of the flyback transformer, using 20-24 gauge enamel wire and insulated from the ferrite core with Mylar tape. Do the feedback winding first, then the bifilar primary winding. Position all leads to avoid a short, and be sure the high-volt- age common is grounded (see text}. high-voltage common goes to ground. Preliminary checkout Check the power-supply before connecting the voltage tripler. Use a voltmeter to be sure the flyback transformer high-voltage output lead isn't shorted, or a shock hazard could occur; an os- cilloscope would be useful. Also, you need some way to measure high voltage; if you don't have a high-voltage meter, you can use a voltage divider with a normal meter, as shown in Fig. 8 with a 10O;l ratio. The RCA focus divider shown is a standard TV part, used to reduce the potential at the CRT anode for use on the focus elec- trode. It has a 200- and a 40- megohm resistor (R5 and R6) in series internally. To achieve 100:1 reduction, R6 goes in parallel with R7 (external) and a high-im- HVDC TV CRT FOCUS DIVIDER RCA PART* SK3868/DIV-1 FIG. 8— IF YOU HAVE NO HIGH-VOLTAGE voltmeter, this RCA focus divider extends the range of a voltmeter with at least a 10- megohm input impedance by 100:1, so it reads up to 20 kilovolts on a 200-volt scale. R5 and R6 are in series, and R6 goes in parallel with both R7 and the DC voltmeter. GND GrJD FIG. 9— NORMAL ASTABLE WAVEFORMS from the base (a) and collector (b) of either 01 or 02. With IC1 set to 3-4 voits DC, the fundamental is 23.26 kHz. Both are irregular, with sharp, narrow spikes, upward for the collector, downward for the base. The flyback transformer you use may create different waveforms, so expect variations. pedance DC voltmeter. The DC voltmeter used needs at least a 10-megohm input impedance to avoid loading. If the meter is set to 200 volts full-scale, it's full- scale range will now be 20 kilo- volts. TUrn the power off before con- necting to the final high-voltage output terminal at the anode of D10, and dissipate the remaining voltage to ground with an insu- lated clip lead. Set Rl midway, ap- ply power, and measure the voltage across C2. As you adjust Rl, you should see 1.25—5 volts DC or more. Set Rl for about 4 volts DC, and don't proceed until you do. Check the orientation of all semiconductors and elec- trolytics, disconnect the bifilar primary winding center tap [marked with a "5") to remove the oscillator load, and troubleshoot the power supply until you find 58 THE FOIL PATTERN OF THE main PC board in the negative ion generator. the fault. If you use batteries, be certain their terminal potential is at least 6 volts DC. With IC1 set to 3-4 volts DC, measure the as table fundamen- tal frequency with a scope, if pos- sible; it should be about 20-30 kHz. Figure 9-a shows a typical collector waveform of the pro- totype, for either Ql or Q2. Its amplitude is 2.4 volts p-p, double the DC voltage obtained from IC1; it goes 400 millivolts above ground, and 2 volts below. Fig. 9-b shows the base waveform; its am- plitude is 12. 8 volts p-p, going 8.4 volts above ground, and 4.4 volts below. Both of the waveforms are quite irregular, with sharp spikes, upward for the collector, downward for the base, gener- ated by the high inductance of the flyback transformer output winding. Since the inductance, resis- tance, and number of turns in whatever flyback transformer you use may differ considerably by comparison with the version used in the prototype, as well as the current gains and saturation voltages of both Ql and Q2, the waveforms shown here may also vary considerably, so expect vari- ations. The waveforms shown here are shown purely to illus- trate typical responses, not as ironclad guarantees of what you'll see. If you don't have a scope, touch a large screwdriver with a plastic handle to the flyback trans- former output. If the oscillator isn't running, there'll be no spark, so the phasing is wrong. Try reversing wires "1" and "3," and then check the orientation of Ql, Q2, D3, and D4, and the T2 connections. When you get the astable working, disconnect the power and let CI and C2 dis- charge. Final checkout Connect the voltage-tripler to the flyback transformer. For the connection from high-voltage winding to transformer and C3, use wire rated to at least 5 kilo- volts, preferably 18-gauge rub- ber-covered test lead. The com- mon of the high-voltage assembly can be made using ordinary hookup wire since it's at ground potential. Don't forget the trans- former and voltage tripler com- mon connections. With the circuit fully as- sembled and power off, connect the high-voltage voltmeter adapt- er or a high-voltage DC voltmeter to the -emitter needle and com- mon with suitable clip leads. Don't go near the high-voltage output, and position the clip leads to avoid arcing. Apply power, and note the meter, ad- justing Rl for -9 to -14 kilo- volts. Any more, and you'll generate ozone, an undesirable byproduct, which has a peculiar odor. Correct any arcing or coro- na bv insulating the connection with'RTV. FIG. 10— THE ROTOR FOR AN ION MOTOR; it's a 7-inch piece of 16 "gauge wire, with two V4 •inch pointed ends at right angles to the 6-inch center section, as shown in (a). The center is flattened, with an indentation made in the middle with a punch (b). m CD u c > < 59 w o z O DC H O NEGATIVE IONS INSULATING BASE C9 .ogi ; 500V rnn ^JBULB NE1 EARTH GROUND PROJECT FIG, 11— AN EXPERIMENT TO SHOW NEGATIVE ions charging a nearby insulated metal object to high voltage. Negative ions travel through the air, collecting on the empty can on a rubber mat, with an earth ground. As negative ions hit the can, charge builds; at 90-100 volts DC, NE2 fires. The flash rate increases as distance decreases, or when the emitter is aimed at the can. Don't arc the high voltage to ground with power on to observe a spark, or you'll damage the high voltage rectifiers. You should do so when power is off. when no shock hazard exists. Unplug the line cord and touch the ground prong to the emitter needle; otherwise you can use an insulated clip lead connected to ground on battery-operated ver- sions. Using the ion generator You can use the negative ion generator as an air purifier, to clear a room of smoke, dust, or pollen. As the negative ions are generated, they'll attach them- selves to any particles, and fail to the floor or a nearby grounded object. Other phenomena can also demonstrate that it really does emit negative ions. The "ion motor" is quite dramatic, and proves the existence of negative ions and that they can perform work. Ion propulsion is a viable means of space travel, since esca- ping ions at high velocity can pro- duce speeds approaching the speed of light in free space. The ion-motor experiment demon- strates the principles that are in- volved with Newtonian action and reaction. An ion motor can be built as shown in Fig. 10: it's just a 7-inch h - 3'/s INCHES - H □ cc THE FOIL PATTERN OF THE voltage-tripler PC board in the negative ton generator. piece of gauge 16 wire with both ends sharpened to fine points, and bent at right angles, as de- picted in Fig. 10-a. The bent ends are each 0.5 inch long, while the main body of the rotor is 6 inches long. The middle of the center section is slightly flattened in a vise, and an indentation is made on one side with a punch, in the exact center of the 6-inch seg- ment, as shown in Fig. 10-b. You have to find the exact balance point, in order to balance the ro- tor on the emitter needle at the indentation point of the I6gauge wire. However, Fig. 10-t» shows the rotor from below, with the right tip pointing upward, and the left pointing downward. Thus, the rotor shown rotates clockwise when viewed from below, and counterclockwise when viewed from above. When the indenta- tion is on the bottom (the right tip pointing downward and the left pointing upward), the reverse is true. In Fig. 10-a, the rotor shown rotates clockwise when viewed from above, since the tips are reversed in orientation to those of Fig. 10-b. You can ob- viously make the rotor turn in ei- ther direction as long as both rotor tips face in opposite direc- tions. The emitter needle won't work with its point covered. Instead, the ends of the rotor now become the emitters. Since negative ions are emitted in opposite direc- tions from each end, it spins like an aircraft propeller, reaching high angular speed in just a few seconds. Actually, the word "emitted" is a misnomer, since neither the needle nor the rotor actually ab- sorb or generate ions, per se. Rather, polarized air molecules collide with the surface of the pointed tips of either the needle or the rotor, absorbing electrons from the molecules, or releasing them to un-ionized atoms. The absorption process produces positive ions, the latter genera- tion process produces negative ions. Since the effective discharge surface area is doubled when using the rotor, as opposed to the needle, the negative ion density emitted from each rotor tip is about half of that emitted from continued on page 70 w OUBLESHOOTING , H1LP; The horizontal output transistor is a critical component in any TV set Let's examine some of the procedures involved in measuring its output BRIAN PHELPS FOR ANYONE WHO HAS EVER TRIED TO repair a television with defective signals throughout, or changed a horizontal output transistor only to have it fail once more, we have a technique that can save hours of work and needless replace- ment of parts. All you have to do is check the "HOT pulse," or the signal at the collector of the hori- zontal output transistor. Let's see why this waveform is so impor- tant, and some key procedures for measuring the signal. The HOT pulse is important because it performs many func- tions other than just sweeping the CRT beam horizontally. Some of the key functions of the hori- zontal output waveform are: • It generates 0.7 amps of hori- zontal deflection current every 63.5 microseconds. • It generates a 700-1.500 volts peak-to-peak retrace pulse every 63.5 microseconds. • It generates 15,000-30,000 volts DC for the picture tube. • It generates 3,000-8,000 volts DC for the focus circuit. • It deli vers "trace-derived" high- cur rent DC power from 16 to 30 volts to operate most circuits. • It delivers "retrace-derived" low-current DC power of 185 to 220 volts. • It provides 6.3 volts for the pulse current of CRT filaments. • It is a critical safety feature. • It provides accurate pulse volt- ages for the tuners frequency- synthesis power source. What to look for The horizontal output pulse supplies operating voltages for the entire TV. It is therefore the most important waveform to check on every TV before and after changing parts. Note: In order to make any of the follow- ing measurements, your scope must be capable of measuring, and have input protection up to 2 kilovolts or more. Also, a digital- readout oscilloscope, although not essential to troubleshooting, will make it easier to make the measurements. The first thing to check when analyzing the horizontal output pulse is the wave shape: it should look like the one shown in Fig. 1, and be symmetrical in shape dur- ing the retrace time. A wide peak at the top of the retrace, or deep saddle conditions, can be caused by an off frequency or glitch in the horizontal transistor base- drive signal. Such problems are often caused by a change in the value of the output-transistor timing capacitors, or by an exces- sive load on a B + supply. Any excessive ringing or noise is a clear indication of deflection- system problems, such as a cracked integrated high voltage m a x c > X CO to 61 MOO EL SCE1 RG. 1— THE WAVE SHAPE should be sym- metrical during the pulse retrace time. transformer (IHVT) core, or open or shorted IHVT windings. Fig- ure 2 shows an example of a faulty horizontal output. Make sure the waveform looks good be- fore you proceed. Check to see if there are any noise pulses during the trace time. Many of the noise pulses may not be detected when view- ing the low-level horizontal wave- forms, but they become very noticeable at the collector with in o z o a h- O LU o < CI FIG. 2— HERE'S AN EXAMPLE of a faulty horizontal output. Make sure the wave- form looks good before you check any- thing else. an amplitude reaching 1500 volts peak-to-peak. The noise could cause symptoms from drive lines in the video picture to faint noise throughout the TVs circuits. First measure the DC voltage level of the horizontal waveform. In Figs, 1 and 2 you can see that the digital display shows approx- imately 118 VDC, which is the regulated B + voltage. Next mea- sure the peak-to-peak voltage of the waveform. As you can see from Fig. 3, the display shows 905 volts peak-to-peak. The frequency of the waveform must also be measured. That's as simple as pushing a button on a digital scope. Figure 4 shows the FIG. 3— THE PEAK-TO-PEAK voltage of the waveform should be between 900 and 1500 volts peak-to-peak. It's shown here as 905 volts peak-to-peak. frequency to be 15.7343 kHz. If everything checks out so far, you know the condition of the regu- lated B+ supply, that the TV is not in the shut-down mode, and that the horizontal oscillator is locked to the composite video sync pulse. The duty cycle of the horizontal transistor output waveform is helpful in troubleshooting. The manufacturer specified that the retrace time should be from 11—14 microseconds, and the trace time should be 49—50 mi- croseconds. Those recom- mended duty cycles should be observed when troubleshooting. The time-duration measure- ment of the retrace pulse should be made between the 10% levels TTTT7 \ $t t n C«AW A CHAN I' o FIG. 4— THE FREQUENCY of the wave- form is important; here it is measured to be 15.7343 kHz. of the waveform. Some digital scopes are equipped to measure portions of a waveform with a de- lta-time feature. To make that measurement on a digital scope, ■ align the pulse so that the top of it is at the 100% graticule mark- ing and the bottom is at the 0% marking, using the volts/division and calibration knobs. (Make sure your scope will allow a ecu- continued on page 70 IS ^ r~4 C QF=l E= MODEL S,"C1 FIG. 5— THE TIME DURATION of the re- trace pulse should be between 11 and 14 microseconds; 12.83 microseconds in this case. 62 MOST PEOPLE INVOLVED IN ELEC- tronics, either as a hobby or a profession, start out by building simple electronic kits. Along the way, they become familiar with electrical terms like voltage, cur- rent, resistance, power, and ener- gy, developing a "common-sense" knowledge of them, without fully understanding their meaning. When asked, "What is a volt?", one might be tempted to respond by quoting Ohm's law: "If 1 amp flows through a 1-ohm resistor, a 1-volt potential is developed across it." That definition, how- ever, isn't much help in defining a volt because one electrical term is used to define another, which Here's a refresher course that will help you brush up on standard electric quantities. mass is the kilogram, kg, which is 1000 grams, the variable being either m or M. The difference in usage is that m, with or without subscript, normally denotes the mass of an object. While M can also be used this way, it generally refers to very large, celestial bodies, such as the earth, sun, and moon. Mass is a measure of quantity, not to be confused with weight. Weight is the force due to gravity, which varies slightly over the sur- face of the earth, due to the change in altitude relative to sea level. The standard kilogram is a platinum-iridium (Pt-Ir) alloy cyl- inder at the International Bureau leads to vicious-circle reasoning. A proper definition of electrical quantities demands examining length, time, mass, force. charge, and some simple atomic physics. Standard units In any scientific field, accurate and reproducible measurements must be possible. The results of a scientific experiment must be de- scribed in well-defined units. Since the metric system will eventually prevail worldwide, all derivations here will be metric, although British units will be mentioned occasionally, as a frame of reference. We'll now examine length, time, and mass, the basic units from which all other quantities are derived. In some cases, a given letter may have multiple uses as a variable and/or a unit, such as the letter C, which is used as both the variable of ca- pacitance, and the unit of charge. Italic lettering will be used when a label is used as a variable, to avoid confusion. Thus, C will denote the variable of capacitance, while C will indi- cate the coulomb. The standard variable for DALE NASSAR length is I, although other varia- bles are similarly used, especially d for distance, s for displace- ment, and x, y, and z, relative to a set of axes. The standard metric unit of length is the meter, abbre- viated m, equal to 39,37 inches. The meter is defined as 1,650,763.73 wavelengths of or- ange-red light emitted by Kryp- ton (Kr)-86 in electrical dis- charge, a phenomenon that can be remeasured with great preci- sion and comparative ease, given the right equipment. The standard variables for time are t and T, and the stan- dard unit is the second, s. Nor- mally, t with no subscript is considered to be time as a run- ning, independent variable. By contrast, t with a subscript, like t , t,, and so on, indicates either an initial or specific reference time. The variable T. with or without subscripts, is normally used in electronics to indicate ei- ther periods or specific times on waveforms. One second is de- fined as 9,192,631.770 cycles of radiation from Cesium (Ce)-133. Clocks using Ce-133 from Hewlett-Packard (HP) Corp. are typically accurate to 1 ps. The standard metric unit of of Standards (IBS), in Sevres, France. When an object exactly balances the I -kg standard on a balance, it's said to be a Tkg mass, weighing about 2.21 lbs on earth. The British equivalent of the kilogram is the slug, where 1 slug = 14.59 kg. The first derived quantity is force, F. The metric unit is the Newton, N, named after Sir Isaac Newton. Thus, 1 N is the force (a push or pull) needed to accelerate a 1-kg mass at 1 m/(s 2 ), written as 1 N=l kgxm/ts 2 ); this nomen- clature is explained below. Note how this definition uses length, mass, and time. For example, suppose you have a toy car with a mass of I kg, and you move it along the surface of a long smooth table. Neglecting fric- tion, no additional force is needed to keep the car moving at its present velocity, the variable for which is v. However, to accelerate or de- celerate an object means to change its velocity, whether in magnitude (speed) or direction. To do so always requires a force, even in space, in the absence of gravity. If the car uniformly accel- erates at 1 m/s per second, that means its speed increases by an — : m CO c > < m o O DC p o LU _l LU 6 a < L£ additional 1 m/s with each pass- ing second. The variable for ac- celeration is a. while deceleration is a negative acceleration. On or near the earth's surface, the ac- celeration due to gravity is pre- sumed constant for practical purposes, and is denoted by g = 9.8 m/(s 2 ) =32.2 ft/(s 2 ). Thus, 1 kg = 9.8 N on earth, and since 1 kg = 2.21 lbs, then 9.8 N = 2.21 lbs, or lN = 0.2251b. A concept that's very closely re- lated to force is momentum (p), also known as impulse and is the product of mass times velocity. Momentum is defined by p = mXv=Fxt. Momentum, like velocity, acceleration, and force, is a vector quantity, in that it has both a magnitude and a direc- tion, whereas energy (whether kinetic or potential) is a scaler, possessing only a magnitude. Throughout this article, we'll discuss several other derived units, all of which are listed in Table 1. The discovery of electric charge Electric charge was first re- corded in 550 B.C. by Thales of Miletus (Greece, c. 640-546 B.C.). He noted that if amber were rub- bed with fur, it attracted small objects, such as bits of cork. The Greek word for amber is "elek- ton," the origin of "electricity." He also found that other objects re- acted similarly if rubbed with a suitable material. Such objects, after rubbing in this fashion, possess a net electric charge, or become electrified. A glass rod will become electrified when rub- bed with silk, and a lucite or hard rubber rod will become electrified when rubbed with fur. Both rods contain different kinds of electric charge, shown by the simple experiment in Fig. 1. If the electrified glass rod is suspended at its center by a long thin thread so that it rotates easi- ly, it's repelled by a second sim- ilarly charged glass rod nearby, as shown in Fig. 1-a. If the charged lucite rod is brought near the charged glass rod, attraction oc- curs, as shown in Figure 1-b. That simple experiment illus- trates the basic principle where it can be observed that two sim- ilarly charged objects repel, while two oppositely charged objects attract. One very important property of TABLE 1— LIST OF PRINCIPAL Quantity Variable(s) and defining equations Unit (MKS unless otherwise noted) Dimensional Equivalents Length (dis- tance or dis- placement) 7,d,s,x,y,z meter (m) m Time t,T second (s) s Mass m,M kilogram (kg) kg Velocity (magnitude is speed) V m/s m/s Acceleration a (general) m/s 2 m/s 2 g (due to gravity) MKS: 9.8 m/s^ CGS: 32.2 ft/s 2 Force (a push or pull) F( = m x a) Newton (N) kgxm s 2 Momentum (impulse) p(=Fxt) ( = m x v) kgxm s kgxm s Energy (work) W joule (J) kgxm 2 s a Charge, or electric flux q. Q. *d coulomb (coul or C) for charge, or lines for electric flux 6.24x1 01 se Electric potential (EMF or voltage) V volt(V), orJ/C kgxm 2 Cxs2 Current \,\ ampere (A) C/s Power P watt (W), or J/s kgxm 2 s 3 Power density S W/m 2 kg/s 2 Electric field strength (or intensity) E V/m kgxm Cxsz Electric flux density D = <1> D /A 1C/m 2 = 1Axs/tn 2 "IC/mz Magnetic field strength (or intensity) H Am C , mxs charge is conservation. In any closed circuit involving capaci- tors, if a charge of - Q appears on one plate, an opposite charge of + Q must correspondingly ap- pear on the other plate. In a cir- cuit that's off, the total initial displaced charge must be zero. For charge to be conserved, that must also apply when the circuit is on. Thus, in any closed circuit, the net displaced charge must be zero, which is something that be- comes very important when dis- cussing capacitance. The atom lb thoroughly understand elec- 64 AND DERIVED QUANTITIES Quantity Variabte(s) and defining equations Unit (MKS unless otherwise noted) Dimensional Equivalents Magnetic flux <1> B = BxA CGS: maxwell gxcm 2 Cxs MKS: 1 Wb=1 Vxs 8 = 10 maxwell kgxm 2 Cxs Magnetic flux density B=(ixH CGS: 1 gauss (G) = 1 maxwell/cm 2 g C> s MKS: 1 tesia (T) = 1 Wb/m 2 = 1 Vxs/m 2 kg Cxs = 1 N/(A >' m) 4 = 10G Current density J = l/A, = ixE C m 2 xs C m 2 x s Resistance R = Vi\ = px/ A Jl, V/A kgxm 2 sxC 2 Conductance G=1/R siemen (S), A'V [formerly the mho am sxC 2 kgxm 2 Resistivity P = RxA / llxm kgxm 3 sxC 2 Conductivity ~ = 1/p S/m sxC 2 kgxm 3 Permitivity e F/m C 2 xs 2 kg x m 3 Permeability P- H/m kgxm C 2 Capacitance C = q/V, = t/R, = exA>/d farad (F), C/V or Sxs C 2 xs 2 kgxm 2 Inductance L = txR, = p.xN 2 xA / henry (H), Sixs kgxm 2 C 2 tricity requires understanding matter. All matter is composed of one or more elements that can't be chemically decomposed any further, like gold (Au). aluminum (Al), and silicon (Si). The smallest complete subdivision of an ele- ment is the atom, as shown in Fig. 2, with an extremely dense central nucleus, containing one or more positively charged pro- tons, and neutral particles called neutrons, and one or more nega- tively charged electrons, equal to the number of protons. The atom in Fig. 2 is lithium (Li), the third simplest atom. Nor- mally, Li has three electrons or- biting a nucleus with three protons and three neutrons. The electrons are much lighter than the protons and neutrons, and orbit the nucleus at very high speed. If electron orbits were drawn to scale relative to the nu- cleus, they'd go way off the page. All electric charge is quantized, or composed of packets of charge. The magnitude of charge depends on the number of elec- trons extra or absent. A single electron is the smallest unit of charge, usually denoted "e". and the magnitudes of all other charges are then integer multi- ples of e. The charge on an electron is defined as negative, while that on a proton is positive. However, the charges are identical in magni- tude. Normally, unionized atoms have as many electrons as they do protons. The opposite charges cancel, leaving no net charge. Electrons have particular orbits about a nucleus: the closer their orbit is to a nucleus, the tighter they're held. The outer electrons are easily removed by friction or light, leaving the atom with a net positive charge, since it would then contain more protons than electrons. An atom may also gain extra electrons, leaving it with a net negative charge; that's why rubbing an object produces net surface charge. When lucite is rubbed with fur, electrons are transferred from the fur to the rod since they're more loosely bound to the fur than the rod, leaving the rod with excess electrons and a net nega- tive charge (the fur becomes positively charged). When glass is rubbed with silk, electrons are transferred from the glass to the silk (they're more loosely bound to the glass than the silk), leaving the glass with a net positive charge. Electric field and Coulomb's law Electric energy, which acts in a space surrounding an electric charge or charged body is called "lines of force. " Figures 3-a and 3- b show the lines of force of iso- lated positive and negative charges, respectively. Figures 3-c and 3-d show the force field pro- duced by two like charges and two unlike charges, respectively. The arrows in the diagrams rep- m oj 35 > ■< 65 CO o z i 2 Q < -X FIG. 1— THIS EXPERIMENT illustrates the acquisition of electrostatic charge. The glass rods in (a) are both positively charged. If one is suspended at its center by a long thin thread so it rotates easily, it will be repelled by a second one brought nearby. If a negatively charged Incite rod is brought near the positive glass rod, at- traction occurs, as shown in (b). resent the direction of force on a positive charge, and the field lines emanate from the charge in all directions. The relative densi- ty of the field lines is proportional to the field strength. In 1785, Charles Augustin Coulomb {France, c. 1736-1806) used a torsion balance to perform delicate experiments to learn about electric forces between ORBITING ELECTRONS ^«r NUCLEUS (PROTONS AND NEUTRONS) FIG. 2— THE SMALLEST complete sub- division of an element is the atom, as shown here lor lithium (Li). The electrons are much lighter than the protons and neutrons, and orbit the nucleus at high speed. If electron orbits were drawn to scale relative to the nucleus, they'd go way off the page. FIG. 3— THESE ARE "LINES OF FORCE" DIAGRAMS, (a) and (b) are isolated positive and negative charges, (c> and (d) are two like charges and two unlike charges, respectively. pairs of charged objects; a basic version is shown in Fig. 4. The force between the charged balls is determined from the torsion (twist) in the quartz fiber. Coulomb found that the force, F, between charges Qj and Q 2 is directly proportional to their product, and inversely propor- tional to the square of their sepa- ration, R. That relationship is known as Coulombs law, and is expressed as F = k(Q! xQ 2 ]/(R 2 ), where k is the Coulomb propor- tionality constant, which de- pends on the medium. Cou- lomb's Law is only valid for R much greater than the radii of Q, and Q 2 . The units of F are in New- tons, N, while R is in meters, m. The signs of Q , and Q 2 depend on the type of net charge, whether + or - The unit of charge is the cou- lomb, C. In a vacuum, k = 9x 10 9 (Nxm 2 )/C 2 : the value in air is slightly higher. If Q,=Q 2 = 1 C, and R = I m, then F=9xl0 9 N. Thus, 1 C is the charge, that when in vacuum 1 m from a sim- ilar charge of identical or op- posite sign, yields either a repulsion or attraction, respec- tively, of 9 x KPN. The magnitude of the electron charge e was first measured in 1909 by Robert Andrews Millikan (USA, c. 1868-1953). Measuring the charges on charged droplets of oil suspended against gravity in an electric field, he found that all charges are integer multiples of 1.6 xlO" 19 C/electron, or 6.25 xlO 18 electrons/C. As stated above, a charged par- ticle in an electric field is subject to a force. If electrons aren't tight- ly bound, as in the outer orbits of metal atoms, they actually move; such materials are conductors. Materials where essentially no charges are free to move are non- conductors, or insulators. Dif- ferent types of materials have different degrees of conductivity. The unit of conductivity is the Siemen (ct), which is the re- ciprocal of resistance, which we will discuss shortly. Electric current and the ampere Since conductors contain rela- tively mobile electrons, many are always in motion even in the ab- sence of electric field due to ran- dom thermal vibration. Such 66 FIG. 4— IN 1785, CHARLES AUGUSTIN COULOMB used a torsion balance like this to measure electrostatic forces between pairs of charged objects by measuring the torque (twist) in the quartz fiber, to determine the proportionality constant. The force F between them is directly proportional to their product of their charges, and inversely proportional to the square of their separation R. motion is fairly rapid, with an in- stantaneous velocity of about 10 5 m/s. Electrons undergoing such motion in the absence of an elec- tric field follow an erratic zig-zag path, remaining in the same lo- calized region, as shown in Fig. 5-a. When an electric field is applied to a conductor, the erratically moving electrons drift due to the force generated by the field, caus- ing an electric current, as shown in Fig. 5-b. Drift velocity is much lower than instantaneous ve- locity; about lmm/s compared to 10 5 m/s for the instantaneous ve- locity when no electric field is present. The variable for current is ei- ther i or I, for AC and DC current, respectively. The unit of current is the ampere, abbreviated either amp or A, after Andre Marie Am- pere (France, c. 1775-1836). By definition 1 A=l C/s, indepen- dent of conductor area; the sym- bol A is used for the amp, as distinguished from A for area. If 1 A flows in a wire, then 6,25 x 10 LS electrons pass through a cross - section of it every second. Many people incorrectly as- sume that electric current flows at an extremely high speed, when it literally moves at a snails pace! It is the electric field that moves down the conductor at very high speeds. It can be mathematically shown that if several amps of cur- rent (either AC or DC) flows through standard household copper wire, the drift velocity of the electrons move only a fraction of a millimeter per second, but those slowly creeping electrons produce considerable heat due to friction, in the wire. A volt by any other name... The definition of potential, or electromotive force (EMF) in- volves the concepts of work and energy. Energy is the ability to do work. Work results in motion of an object, and is defined as the product of the force applied to an object and the distance through which it travels. The unit of work is therefore the Newton-meter (N- m). The unit of work, or one New- ton-meter, is called a joule, abbre- viated J, after James Prescott Joule (England, c. 1814-1889). For example, if a force of 5 New- tons is required to push an ob- ject, and that object moves a distance of 3 meters in the direc- tion of the applied force, then 15 joules of work is performed. Whatever pushed the object ob- viously had to have the initial en- ergy to do so. The concept of work and poten- tial difference can be illustrated by examining the basic operation of a battery. Two terminals of a battery consist of two unlike charges ( + and - ) that maintain a constant potential difference by chemical means. Because of the difference in charge, an electric field must exist between them. That electric field has the ability to do work on an electric charge. For instance, if you wanted to move a positive charge from the negative battery terminal to the positive, you would have to work against the electric field between the terminals. A greater potential difference between battery termi- nals creates a higher electric field, and therefore, it stands to reason that greater work must be done in order to move a charge against it. We have now come to the unit of potential difference, which is defined as the number of joules per coulomb (J/C), or work per charge. This unit is called, as you might have guessed, the volt (V), and was named after Alessandro Guiseppe Antonio Anastasio Volta (Italy, c. 1745-1827). For ex- ample, in a 12-volt battery, 12 J of energy are needed to move 1 C from one terminal to the other; and 24 J would be needed to move 2 C, since 24 J/2 C = 12 volts. The terms voltage, poten- tial difference, and EMF are equivalent, and are very often used interchangeably. Resistance and Ohm's law When current flows in a con- FIG. 5— A DEPICTION OF random thermal motion in (a), versus a nonzero drift ve- locity in (b). to (5 67 ductor due to an electric field, electrons gain energy because of their motion, called kinetic ener- gy. As they move, they collide with atoms of the conductor, dissipat- ing kinetic energy as heat. The conductor can be said to have a degree of resistance to the flow of electric current. Georg Simon Ohm (Germany, c. 1787-1854), for whom the unit of resistance, the ohm (fl) is named, showed that current flowing in a conductor is directly proportional to the voltage across it. That concept maybe apparent to you since we know that a high- er voltage produces a stronger electric field, and therefore exerts a greater electric force on the charges of the conductor. That relationship is known as Ohms law, and can be written as V = IR, where V is the voltage across the conductor, I is the current in am- peres through the conductor, and R is the proportionality con- stant, which is a direct measure of the electrical resistance of the conductor. If the equation is solved for R, we get R = V/I. The unit R, therefore, is in volt/amps and is called an ohm (CI). Ohm's law states that if a current of one ampere flows through a conduc- tor when a potential of one volt is placed across it, the conductor is said to have a resistance of one ohm. Capacitors and capacitance A capacitor is basically two conducting surfaces separated by a dielectric, or insulator, as shown in Fig. 6. The capacitance of an element is its ability to store electric charge on its plates. The larger the capacitance (C), the more charge (Q) will be stored on its plates for the same voltage (V) w o z o ■X H O LU _l u- 6 5 < r£ CHARGED PLATES 101 C(FARADS)=Q/V C DIELECTRIC ELECTRIC FIELD 1E1 FIG. 6— A CAPACITOR consists of two conducting plates separated by a di- electric, or insulating material. When the plates are charged, an electric tield is es- tablished between them. Capacitance (F) = Q/v. across its plates. Capacitance is defined as C = Q/V where capacitance is in units of farads (F). named after Michael Faraday (Great Britain, c, 1791-1867). [f a capacitor is rated at 1 F. then 1 C of charge can be main- tained on the plates when there's 1 volt between them. One farad, of course, is an extremely large capacitance; most practical ca- pacitors have values on the order of microfarads (u.F) or picofarads (pF). Ideally, assuming there is no leakage current between the plates through the dielectric, the charge on the plates can remain intact indefinitely, although such leakage always occurs in actual practice. The factors that affect the ca- pacitance of a capacitor can be seen in the equation c=€ xt r xA'd where e is the permittivity of air (8.85 x 10- 12 F/m), e r is the rela- tive permittivity, A is the area of each plate in square meters and d is the distance between the plates in meters. The preceding equation reveals that capacitance will increase with a larger plate area, or when the distance between the plates decreases. The permittivity fac- tor e is a measure of how well a given dielectric allows electric field lines to be established be- tween the plates. When an in- sulator is used between the plates, the capacitance will in- crease by a factor of e r . The e r factor equals e/e , which is better known as the dielectric constant, k. As a point ofinterest, the rela- tive permittivity € r of air is 1.0006, rubber is 3.0 and that of water is 80.0. You're probably aware that ca- pacitances in parallel add. To show this, consider CI and C2 in parallel across battery Bl of volt- age V, as shown in Fig. 7-a. The total capacitance C T . as shown in Fig, 7-b, can be found by the fol- lowing analysis. If Qj and Q, 2 are the charges on CI and C2, then Qt~9i + Q2- Since the voltage across both CI and C2 is V, then 9, = ClxV, Q 2 = C2xV. There- fore, Q T =(ClxV) + (C2xV) = (CI + C2) x V. Dividing by V gives us Qt/V = CI + C2, but C T = Q T /V, so C T =C1 + C2. The same rea- C1 C2 + t) 3 -Ha C3 1H 0^11+%+ q 3 , -li-tlr-ta^T II C,=C1+C2+C3 V FIG. 7— PARALLEL CAPACITANCES com- bine like series resistors (a). The total ca- pacitance C T =C1 + C2 + C3 (b), (See text for the derivation.) soning is easily extended to any number of parallel capacitors. To combine capacitances in se- ries, consider CI and C2 in series across battery Bl of voltage V, as shown in Fig. 8-a, To find Cj. , as shown in Fig, 8-0, you can see that V = V! + V 2 , and since the total charge around the circuit is zero, Qi = Q 2 = Q- Therefore, Q7 C T =(Q 1 /C1) + (Q 2 /C2) = (Q/ CD + 1Q/C2). Canceling g gives l/C T = (l/Cl) + (l/C2). Inductors and inductance The inductor consists of a length of wire wound into a sole- noidal or toroidal shape, with or without a center core as shown in Fig. 9. When current passes through the coil, magnetic flux lines are established, as shown in Fig. 10. Inductance (L) of a coil is its ability to store energy in the 1/C,=1/C1+ 1/C2+1/C3 +v- b FIG. 8— SERIES CAPACITANCES combine like parallel resistors (a). The reciprocal of the total capacitance 1/C T = 1/C1 + 1/C2 + V C3 [b). (See text for the derivation.) 68 K(TUHNS) U.tCORE) FIG, 9— TWO TYPICAL COIL con- structions are the solenoid (a) and the toroid (to). Inductance in henrys (L) is de- fined as L = N 2 x \lAIL form of a magnetic field. The unit of inductance is the henry. One henry is the amount of induc- tance necessary to produce 1 volt across a coil with a current that changes at a rate of 1 ampere per second, and is expressed mathe- matically as L=E/(dl/dt) where E is the induced voltage and dl/dt is the rate of current change in amperes per second. For most applications. 1 henry is a very large unit of inductance. Inductance is usually specified in units of millihenrys (mH), micro- henrys (u.H) ornanohenrys (nH). Inductance can also be ex- pressed by the equation L = N2X|iA'/ where N is the number of turns of wire, A is the core area in square meters, / is the core length in meters, and parameter u. is the permeability of the material. The permeability of a material is a measure of its magnetic proper- ties, and is determined by the equation where u- is the permeability of air (4xix 10" 7 H/m) and \x T is the relative permeability of the mate- rial compared to air. As the mag- netic properties of a material increase, so does its relative per- meability. Some materials, such as steel and iron, have per- meabilities that are hundreds or thousands of times higher than air, oru, r >100. A coil with no core has a permeability factor of u, r = 1. The inductance can be in- creased by placing a core with a high permeability, such as a fer- romagnetic material, within the coil. Our discussion now leads us to series and parallel inductors. The total inductance for induc- tors in series can be determined the same way as series resistors; L T = L 1 +L 2 + L 3 +...-l-L n . For in- ductors in parallel, the total in- ductance can be found the same way as for parallel resistors; l/L T =l/L 1 + l/L 2 + l/L 3 + ... + l/L N . Power and the watt Power is a measure of the time rate of either expenditure or stor- age of energy, whether electrical, thermal, or any other form. Power, therefore has units of work per time, and is measured in J/s. called a watt (W), named after James Watt (Scotland, c. 1736-1819). To derive the defini- tion of a watt, we must think in terms of the rate at which work is being done on electrical charges. Since 1 A= 1 C/s, and 1 W= 1 J/s, then the proportionality con- stant must have units of J/C, or voltage. Therefore, P = ExI, and since Ohm's Law gives E = I x R, thenP = I 2 xR=(E 5 )/R. Power is directly related to elec- tric and magnetic field quantities mentioned earlier. If you take the product of electric and magnetic field strengths E and H, then ( V7 m) x (Atai) = (V x A)/(m 2 ) = W/(m 2 ). This is power per unit area, also known as power density, and is generally denoted by S. In electromagnetic waves, the electric field strength E and mag- netic field strength H vectors are perpendicular to one another. You can't simply take the arith- metic product of the magnitudes of the vectors at a given point to obtain the power density. For example, the solar con- stant, or the mean power density reaching the earth outside its at- mosphere, at normal incidence, and at a mean orbital radius from the sun, is about 0.14 W/cm 2 . Of MAGNETIC FLUX LINES INDUCTANCE I 1 I I \ ■ l :■ i \ FIG. 10— AN INDUCTOR CONSISTS of a coil of wire wound around a core of air or ferromagnetic material. When current goes through a coil, magnetic flux lines are established. course, since the atmosphere ab- sorbs a considerable amount of this energy, you never actually feel all that power. Similarly, a 100-W light bulb literally radiates 100 J/s, but becomes dimmer the further you get from it because the power is dissipated over a wider area. Some additional points Many interesting and impor- tant derivations can be made from the concepts discussed in this article. We'll take a look at a few examples of some commonly used electrical terms. All timers use time constants, whether capacitive (RC) or in- ductive (RL). For an RC time con- stant, the units are t=RxC= Q-F = ( V/A) x (C/V) = C/A = C/(C/ s) = s. Therefore, the units of an RC time constant are in seconds. A couple of additional, more practical units for both charge and energy are the amp-hour (Ah) and the kilowatt-hour (kWh). A 1-Ah rating is found on many batteries. If a battery is rated at 4 Ah, it can supply 4 A for one hour, or 1 A for 4 hours, or 0.5 A for 8 hours, and so on. Since 1 A=l C/s, and 1 hr = 3.6 xlO 3 s, then 1 Ah = 3.6xl0 3 C. The exact charge obtainable from a battery depends on the current drain, usually decreas- ing as current drain increases, due to heating. Electric utilities rn determine bills from the kWh a your house consumes every > month. Since 1 kW= 10 3 W, lhr= 5 3.6 x 10 3 s, and 1W=1 J/s, then 1 g kWh = 3.6xl0 6 J. B-E 3 NEGATIVE ION CENERATOR continued from page 60 the needle directly. When power is removed, the rotor spins until the capacitors completely dis- charge. Before removing the ro- tor, turn the power off, and discharge any remaining voltage across the capacitors. A simple experiment can show how negative ions travel to a nearby insulated object, charg- ing it to high voltage. With the power on, the negative ions travel through the air, and in doing so, collect on any metal surface. You can show how that works with an empty can as a collector, as shown in Fig. 11. Rest the can on an insulated surface, such as a rubber mat, so the charge won't leak off. Use an earth ground for discharging, such as an AC outlet ground screw or a water pipe. As the negative ions hit the can. charge builds until the can is charged to 90-100 volts DC, NE2 fires, and the process repeats as long as the negative ion generator runs. Start with the can 1-2 feet away; you will notice how the flash rate of NE2 increases as the distance between the negative ion gener- ator and the collector decreases, or if the emitter needle points to- ward the can. Both experiments can run si- multaneously: as the ion motor rotates, dissipating charge into the air, the can collects the nega- tive ions and flashes the neon bulb. Another experiment uses a 40-watt fluorescent tube in a very- dark room; be very careful while handling the glass tube in darkness — they're very fragile and you could hurt yourself if one implodes. Connect a ground wire to a ter- minal at one end. Hold the tube near the grounded end without touching metal. Bring the other end toward the negative ion gen- erator without touching it. The tube should flash or glow, indi- cating the presence of negative ions. As you move the tube away, g both the flash rate and glow tr should decrease. When you're o finished with the negative ion _i generator, turn it off, discharge 5 it, and be sure to cover the emit- □ ter needle with the cork or other S type of insulator. R-E m HOT TROUBLESHOOTING continued Jrom page 62 rate digital readings when it is unsealed.) Select the dual-channel mode, couple channel B to ground, and align the trace so it lies on the 10% graticule marking. Select the time-measurement mode, and set the "begin" and "end" knobs so that the intensified trace section is as shown in Fig. 5, The digital display should show between 11 and 14 microse- conds. (The display in Fig. 5 shows 12.83 microseconds.) If you measure, say, 9 microse- conds, instead of 11-14 microse- conds, even though the peak-to- peak value, the DC voltage, the wave shape, and the frequency are correct, the TV will work for awhile, but will more than likely fail at some point. That's because the horizontal output system sees a 35.7% reduction in retrace time — meaning that retrace is faster and generates higher volt- age. Therefore, the horizontal output transistor is on longer at full-scan conduction, producing increased heat, increased scan- derived power supply levels, and higher voltages throughout the set. All the circuits are now stressed working at the higher voltages. That, in time, will cause components to fail. Your scope can also be used to watch for an instantaneous start-up pulse. Simply connect the scope and preset it to view the HOT pulse. Then, watch the CRT as you apply power to the TV's circuitry. If you see a pulse appear and then disappear, your start- up circuitry is operating and the set is in the shut-down mode. If that happens, service the chassis in a "powered-down" condition by either halving the normal B + level separately, or re- ducing the AC input power to 60-90 VAC. Then monitor the collector of the horizontal output transistor with your scope. Many underlying performance problems can be uncovered by ex- amining specific characteristics of the "HOT pulse." The wave- form shape, symmetry, and duty cycle of horizontal output tran- sistor is critical in diagnosing and troubleshooting electrical malfunctions in your TV set. R-E SWEEP/MARKER continued/rom page 49 RDD104 IC's made by LSI Com- puter Systems, Inc. A 5-MHz crystal oscillator used by ICI7 is programmed via pins 1 and 2 to divide by 1000. Its output at pin 7 is fed to the input of IC18 which divides by either 1,000 or 10,000. depending on the position of the sine range switch. The output is a square wave and provides ei- ther 0.1 second or 1.0 second sampling of the frequency to be measured by the shorting or non- shorting action of transistor Q8. The same precision square wave is differentiated by C61 and R73 to originate a positive updating spike at pin 5 of the counter chip, IC19. The same square wave is integrated by C60 and R74 to pro- vide a reset voltage a few millise- conds after the update. The RDD104 IC needs about 12 volts to oscillate at 5 MHz, and since the counter IC requires 5 volts, dual-voltage supplies are really necessary. The schematic of the peak-hold circuit is shown in Fig. 9. In that circuit, op-amp IC23 amplifies the signal from the device under test about four times. The positive alternation of the waveform is squared and inver- ted by op-amp IC26. That near- square wave is applied to the bases of transistors Q13 and Q14, both of which act as switch- es and behave as either open cir- cuits or shorts to ground. If Q14 is a 2N2219 transistor, it shorts to within 5 millivolts with refer- ence to ground. If a VNO300M power MOSFET is used, it shorts to within 1 millivolt to ground. When QI3 and Q14 act as open circuits, C93 charges to the peak value of the positive alternation, following the rising edge of the alternation and then holding the peak value because there is no discharge path. The flat-top portion of that charge is one seg- ment of the positive contour line. Transistor Q13 discharges C93, and the next time it acts as a short circuit. This varying be- tween charge-time and short-cir- cuit time continues for each cycle. We're going to have to stop at this point. Next month we'll build and test otit the unit. R-E TO imiEZHlIIE^ This month we'll talk about cheap visible lasers, electric motor resources, induction motor controls, new wavelet math theory, and a dual digital potentiometer. DON LANCASTER Let's start off this month's col- umn with a very hackable circuit opportunity that has not quite seen the light of day. At least not yet... Induction motor speed controls Why should it be cheap, easy, and trivial to regulate the speed of your electric drill, yet super expensive and next to impossible to control the speed of a compressor or blower motor on an air conditioner? After all, a motor is a motor, isn't it? Sadly, the answer is no. Those AC induction motors simply were never designed to have their speed changed, and they throw all sorts of really ugly hassles at you when you try to do so. Let's see why that's so. Just about all electric motors are based on two fundamental electrical principles. The first of those is that like magnetic poles repel and op- posite ones attract. The second is known as Fleming's Rule, which states that "a current carrying con- ductor at right angles to a magnetic field will produce a force and attempt to move in a direction at right angles to both the magnetic field and the current." When using conventional current, that produces the familiar right-hand generator rule, wherein your thumb points in the direction of the motion, your index finger towards the south pole of the magnetic field, and your middle finger in the direction of the conventional current. For a motor, the same rule applies to your left hand. The only theoretical difference between a motor and a generator is that you input motion to get an output current with the gener- ator, while you input current to get a force and hopefully a motion with a motor. In reality all motors do some generating, and vice versa. So, your only trick to building a motor is to constantly rearrange your magnetic fields and their strengths so they are either attracting one another or shoving each other away, or use some ongoing combination of attraction and repulsion together. A motor usually consists of a sta- tionary part called a stator and a mov- ing part known as a rotor, or armature. If it's necessary to phys- ically transfer current to your rotor, either brushes and a commutator, or else slip rings are used. Slip rings apply continuous power to your rotor, while fixed brushes and a com- mutator selectively switch in and out chosen windings that happen to be aligned with the brush axis at any particular point in time. You'll find quite a few different pos- sible motor designs. But by far the two most economically important are the series DC motor with brushes, which is sometimes called a universal motor, and the AC induction motor. Let's take a look at each one. Figure 1 shows a universal motor and its torque versus speed curve. You'll recognize this one in your elec- tric drill, hot tub blower, vacuum cleaner, blender, sewing machine, or older car starter. There's a pair of wound stator coils that, when run on DC, will produce a constant stationary magnetic field. In series with the stator coil is a pair of brushes with a commutator, which selectively switch rotor windings in and out so that one or more windings is constantly getting attracted to the fixed stator field. As the armature ro- tates, new windings get switched in by the commutator, so that a more or less continuous attraction, and thus a rotary motion gets produced. The same universal motor works NEED HELP? Phone or write your Hardware Hacker questions directly to: Don Lancaster Synergetics Box 809 Thatcher, A2 85552 (602) 428-4073 almost as well with AC, except some- times you have strong fields and sometimes weak ones as the current alternates. Usually, the mechanical inertia of your load will more or less average all those variations into con- tinuous rotary power. Even with AC, you still always have opposite poles attracting one an- other. They just happen to change their polarity 120 times a second. But they always change together. Note that you can reverse your universal motor by placing a DPDT switch be- tween the commutator and the stator coils. But that can cause excessive wear if the motor brushes were not designed for two-way use. As your universal motor slows down, its torque will increase, which tends to add to the motor stability. As you slow down, the available "twist" increases to speed you back up, and vice versa. Since you have lots of torque at zero speed, your motor self-starts. It may overheat if you stall it perma- nently, but given half a chance, a uni- versal motor easily gets itself up to speed. Any motor is simultaneously a gen- erator, and vice versa, A universal motor that is lightly loaded and run- ning at a high speed produces an out- put voltage and resultant current in series with your input current. The voltage that is generated is known as a back emf, which opposes the input current. When lightly loaded, very lit- tle current is drawn from the supply, since the back emf and its resultant current nearly cancels out the input current, which is real handy from a conservation of energy standpoint. If you're doing no useful work, and if your motor isn't getting particularly hot, then you shouldn't need too much input energy just to spin things. As you add mechanical load, your ^ series machine will become less of a § generator and more of a motor. The g back emf and its canceling current 5 drops, and the input current goes up. — Your new energy needed is mostly § 71 STATOR STATOR ROTOR TORQUE — ■ : ROTOH \ • STATOR TORQUE SPEED SPEED FIG. 1— A UNIVERSAL SERIES motor with brushes used on an electric drill, along with its speed-torque characteristics. The speed of the motors can be easily electronically controlled by using simple circuits. FIG. 2— A SYNCHRONOUS AC MOTOR used on a clock, along with its speed-torque characteristics. The speed is determined by the line frequency. The input current determines how strong a load can be driven. o o LU o Q < transferred to your mechanical load. Again by conservation of energy, you're putting more energy in so you can get more energy out. Neglecting nonlinearities such as air resistance, the speed of a univer- sal motor for a given load is deter- mined only by the input current. You raise your current to go faster; reduce it to slow down. That means you can just throw any old high power resistor in series with your universal, motor to control its speed, just like sewing ma- chine motors used to use, Betteryet, you can use a far more efficient triac style light dimmer for control. Best of all, you can sense the back emf or otherwise measure the actual motor speed and use electronic feed- back with a triac or SCR circuit which is only slightly more complex than a plain old dimmer. That gives you a tightly regulated speed control plus the ability to run real slow with lots of torque. The bottom line is that it's trivial these days to electronically regulate the speed of a universal motor. We've seen several circuits in past issues and in those Hardware Hacker II re- prints. LSI Systems is a good source for fancy universal motor controller chips, while lots of detailed applica- tion notes appear in the usual triac data books from Motorola, SGS, Texas Instruments, and several others. So what's wrong with universal motors? If they are so universal, why aren't they used everywhere? The biggest problem lies in their brushes. Brushes wear out. They are ineffi- cient. They are both acoustically and electrically noisy. They spark and can start fires or explosions. And those problems really get out of hand when you need more horsepower. Look around, and you'll see that virtually all universal motors in your home only run on an intermittent basis. Mostly because the brushes cannot run continuously without grinding themselves into oblivion, or driving you up the wall with noise. Ideally, we would like to conjure up some scheme to get power onto the rotor without any brushes or other physical contact. And that's where the induction motor comes in. Figure 2 shows a brushless beastie known as an AC synchronous motor. It has a wound stator and a perma- nent magnet rotor. Assume that we are plugged into the 60-Hz AC line and that the rotor just happens to already be spinning at 3600 RPM. On a positive line peak, the north magnet pole will get attracted to the upper stator coil. By the time your magnet is pointing straight up, the current will be going through zero and there will be no mutual attraction or repulsion. Soon afterward, the line current swings negative, and that op- posite polarity starts repelling the magnet, continuing it on its merry way. The exact opposite happens to the other pole, and the motor will con- tinue to spin. The synchronous speed is set only by the number of poles and the line frequency, and is totally Independent of your input current. The two pole synchronous motor runs at 3600 RPM off the 60-Hz line; a four pole job spins at 1800 RPM, and so on. We can see that a synchronous motor is real handy for maintaining a constant speed. Important uses are in electric clocks, phonograph motors, timers, chart drives, and other lower power uses where an ab- solutely constant speed, indepen- dent of the load or input current, is essential. What happens when we apply too much of a load? If your magnet gets 90 mechanical degrees out of phase, there will be no attraction or repul- sion, and zero power routed to the load. If it gets further out of phase, it actually tries to stall itself. Therefore, the slower the speed, the less the torque. You really have a two-speed device here: 3600 RPM and RPM. One consequence here is that any true single-phase synchronous motor will not start by itself. You will have to help it along with a switchable starting winding, a pole shading, an iron hys- teresis cup, or a second or third wind- ing driven from a two-phase or three- phase source. A second consequence is that the speed of a synchronous motor with varying load or current can end up unstable. If it ever breaks out of sync, you almost surely will stall. That hap- pens because a slowdown produces less torque, which in turn produces less speed. Just the same as an auto in too high a gear for the grade. The load current does decide how large of a load it can drive at syn- chronous speed. The more input cur- rent, the more power you can deliver to the load without having to break your synchronization. Figure 3 shows a variation on a synchronous machine known as the AC induction motor. It is by far the most common motor in use today. You will find AC induction motors in your air conditioners, heater blowers, 72 ANALOG POTENTIOMETER OUTPUTS STATOR ROTOR STATOR \—WA— I poo :• TORQUE SPEED FIG. 3— AN AC INDUCTION MOTOR used on a washing machine, along with its speed-torque characteristics. The current controls the speed over a very narrow range between the optimum slip speed and the synchronous speed. To control the speed of this type of motor over a wider range, you must use a complex cycloconverter circuit that can change both the input frequency and current. SERIAL DATA CLOCK SERIAL DATA IN DATA LATCH FIG. 4— A DUAL DIGITAL POTENTIOMETER using the Dallas Semiconductor DS1 267. A 17-bit serial word determines which of the 256 steps for each potentiometer gets selected. Unlike EEPOT chips, the settings are easily read but forgotten on power- down. A serial 'output lets you daisy chain your digital com- mands. washers, most table saws, dish- washers, dryers, drill presses, water pumps, and many circulation fans. Motors used in those types of products are also the ones you would most like to be able to inexpensively control the speed of. You would es- pecially like to raise the efficiency of heating and cooling systems. The concept of the AC induction motor was positively brilliant. Tesla strikes again. Somehow you have to get currents onto the rotor, but we definitely want to avoid any brushes or other mechanical contacts. Question: What do you get when you have coils and iron driven from AC current? Answer (A) a motor, or (B) a transformer (!), Instead of brushes or slip rings, you transformer couple the rotor cur- rent in an induction motor. That's usu- ally done by creating a special low- impedance transformer secondary known as a squirrel cage. The pur- pose of the squirrel cage is to serve both as the transformer secondary and as rotor coils to simulate the rotor magnet of Fig. 3. But not so fast. Literally. If you're running at synchronous speed, no lines of flux will be cut, and there will be no current induced into the squir- rel cage. Which gives you syn- chronous speed, but zero power. Now, let your speed slip just a little bit. There's now a very low-Frequency AC current induced in the squirrel cage. That creates a changing mag- netic field, and you now have more torque than you do at synchronous speed . If you lower the speed slightly, you create even more torque. But if you slow it down too far, your torque starts dropping radically Thus, an AC induction motor has optimum torque at a speed which is only modestly less than syn- chronous. That's why your "quarter horse" motor is usually rated at 3450 RPM for a two-pole motor and 1734 RPM for a four-pole one. As you can see, we have a well- behaved torque-speed curve be- tween the synchronous speed and the optimum, but only a slightly slow- er peak torque speed. Below the peak speed, you'll have the same in- stability and dropout problems that you'd have with a pure synchronous machine. Like a synchronous motor, a single- phase induction motor will not start itself. Usually there will be a second starting winding that gets kicked in only when getting the motor up to speed. Other starting variations can include a pole shading or multiple phase windings. In theory, you could reverse your induction motor by reversing the di- rection the starting method shoves the rotor. Details vary with the motor type. In some cases, the only way to reverse the motor is to remove the rotor and put it back in pointing the other way. Another problem with induction motors is that the optimum motor speed is usually far too fast for useful real-world work. You almost always have to use pulleys and belts or some other speed-reduction scheme. Or go to lots and lots of poles, as is done in those fancy ceiling fans. Thus, any attempt to control the speed of an induction motor with a series resistance or a simple phase control is doomed to failure. 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MO 63017 (314) 532-3505 CIRCLE 30S ON FREE INFORMATION CARD Northern PO Box 1499 Burnsville, MN 55337 (800) 533-5545 CIRCLE 318 ON FREE INFORMATION CARD CO O Grainger 2738 Fulton Street Chicago, IL 60612 (312) 638-0536 CIRCLE 309 ON FREE INFORMATION CARD PCIM 2472 Eastman Avenue, Bid. 33-34 Ventura, CA 93003 (805) 650-7070 CIRCLE 319 ON FREE INFORMATION CARD SAE 400 Commonwealth Drive Warrendale, PA 15096 (412) 776-4970 CIRCLE 320 ON FREE INFORMATION CARD z o cr F u 111 _l LU 6 < Herbach & Radernan 401 East Erie Avenue Philadelphia, PA 19134 (215) 426-1700 CIRCLE 310 ON FREE INFORMATION CARD that will never work and probably will burn up your motor as well. It's like plowing with a pig. Now, you can use current control to alter the speed of your motor be- tween its synchronous speed and its slightly slower optimum speed. But that range is usually far too narrow to be useful, unless you're willing to vary the frequency applied to your motor. But since the impedance of a motor varies with frequency, you'll also want to vary the voltage or the input cur- rent as you change frequency. Keep- ing the magnetic flux at a constant strength seems like a good starting point, so raising the voltage with the line frequency seems like a good idea. You'll also have to quite accu- rately sense your motor speed at all times, and feed back all of that infor- mation into your controller. In addition, you do have to guaran- tee that the starting windings do not kick in at slower speeds. Most start- ing windings are for very intermittent duty only and will rapidly burn up if run continuously. Circuits which sense motor speed and vary both the frequency and the current are often known as cycloconverters. Yes. you can get them. One major supplier is Asea Brown Bovari, a Swiss firm with a wide range of induction motor speed controls. But they're not cheap. And cycloconverter-controlled induction motors tend to whine a lot, owing to nonlinear magnetic harmonics in the audio range, unacceptably so for many uses. But a $19.95 wide range and quiet quarter horse induction motor speed control is not likely to show up in your hardware store in the next few months. Even though we do have lots of better magnetics and new intel- ligent-power integrated circuits avail- able that should make the task far easier than it once was. What you're more likely to see are modifications of traditional induction motors which can make them more amenable to electronic speed con- trol. You'll come across such things as dual stators, variable-frequency rotors, and internal speed sensors. What's the bottom line? A lot ot thought and time and effort has gone into induction-motor speed controls for several decades now, and nothing really useful has yet seen the light of day Despite an incredibly big bag of nickels waiting for the winner. 74 I strongly urge you to try and hack this one. But don't expect any prompt or easy results. Needless to say, we here at Radio-Electronics edi- torial will be very interested in the first hackable, wide-range, and sanely priced quarter-horse induction-motor speed-control construction project. Electric-motor resources To get you started, I've put to- gether some electric-motor re- sources for you in the resource sidebar this month. Here's a quick rundown... One very good starting point is the $5.00 Small Motor and Gearmotor handbook from Bodine. W.W. Grainger, of course, is by far the lead- ing wholesale distributor of just about any type of small motor. And your best source for electric motor hack- ing books remains Lindsay Publica- tions. Good surplus motor sources in- clude C & H Sales, Northern, JerryCo, Herbach and Rademan, and Fair Radio Sales. Two higher-volume suppliers of smaller motors are Molon and Fasco. As we've just seen, one interna- tional source for AC-induction motor- speed controls is Asea Brown Bovari. Important trade journals involving motors include Motion, PCIM, Machine Design, Appliance, Appliance Manufacturer, and Design News. Some of the more scholarly stuff comes down in either of the IEEE Transactions on Energy Conversion or their IEEE Transactions on Indus- trial Applications. For automotive motor uses, try the publications in the SAE library. Uh, even though this is one of our longer resource listings, I've got a hollow feeling I'm missing several ma- jor and obvious motor hacking re- sources here. Something that you electrical types out there might be able to help us on. So, for the first of this month's con- tests, let me know what I've left off the sidebar in the way of motor re- sources. They'll be all the usual Incredible Secret Money Machine book prizes, along with an all ex- pense paid CFOB Thatcher. AZ), tinaja quest for two going to the best entry of all. Or, as a second contest, just add to our ongoing induction motor speed control dialogue in some useful way. As usual, be sure to send all your written entries directly to me at Synergetics, rather than over to Ra- dio-Electronics editorial. Dual digital potentiometer A ways back (Hardware Hacker, January 1989), we looked at a Xicor X9W3 digitally controlled 100-step potentiometer. This dude was a sin- gle-channel device, had a permanent memory that remembered even when it was unpowered, and let you incre- ment or decrement the potentiome- ter setting with a simple interface. But it had no way to sense the pres- ent setting, nor any way to jump to any setting without moving through all of the intermediate ones. Dallas Semiconductor has just in- troduced a new DS1267 dual digital potentiometer chip that has strengths where the X9103 was weak, and vice versa. As Fig. 4 shows us. this one gives you two 256-step potentiometers in a single package in your choice of 10K, 50K, or 100K total resistance. Those are not memory devices. They return you to a 50% "mid- wiper" position on power up and must get rewritten each time. As is becoming common on many new chips these days, there is a three- wire serial control provided, intended to interface with three computer port lines. To set up your potentiometers, clock in seventeen data bits by using the clk and dq lines, while keeping the rst line high. Eight of those bits are for the first potentiometer, eight for the second, with the final bit being used to optionally cascade the poten- tiometer pair into a single potentiom- eter with 512 steps of resolution. Drop the rst line to enter the new settings for the potentiometer pair. There's also a serial out that lets you read out the present settings or else cascade chips for such things as multi-band equalizers. As long as rst remains high, your old setting gets saved. Thus, you can do 17 clocks to read out your existing settings, and 17 more to enter the new ones, without getting any noise or glitches. The digital end of the chip works off your usual and +5 volts. The ana- log end can be anywhere from to + 5 volts with a grounded VB sub- strate pin , or can be used over a - 5 to +5 volt range with -5 volts on Made in the U.S.A. Building the best DMM for the money is no accident The new RMS225 was carefully designed to give you what you wanted at a price you could afford Visit your local distributor today and you'll agree the choice is obvious. Fluke ModelTT Beckman Industrial RMS225 3-Vj Digits 4 Digits 3,200 Counts 10,000 Counts 0.3% Accuracy 0.25^ Accuracy Touch Hold® Probe Hold™ 31 Segment Analog Bar Graph 41 Segment Analog Bar Graph 2,000 Hour Battery Life 1,000 Hour Battery Life 10A Range (Fused) ioa Range ifukid Protective Holster Protective Holster 3 Yr. Warranty 3 Yr. Warranty - True RMS - Auto Mln Max™ - Relative Mode S159' SM9 • Touch Hold is a registered trademark of the John Fluke Mfg. Co., Inc. "1990 Fluke and Philips Catalog Beckman industrial" An Affiliate of Emerson Electric Co, tnstrurnmlatictn Products Division 38S3 Ruffin Road, San Dtega CA 92I23-IS9S (6(9) 49S-320O • FAX (619) 26MI172 - TUt 249031 Otilsttfc California 1-800-8>4.270S Within California 1-SD0-227-97BI © 1990 Beckman Industrial Corporation Speciflcatkirks subject lc, change without notice, flute ls a registered trademark of John Flute Mf£ Cti. 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CIRCLE 178 ON FREE INFORMATION CARD Burr-Brown 6730 South Tucson Blvd. Tucson, AZ 85706 (602) 746-1111 CIRCLE 321 ON FREE INFORMATION CARD Circuit Specialists PO Box 3047 Scottsdale, AZ 85271 (800) 528-1417 CIRCLE 322 ON FREE INFORMATION CARD Dallas Semiconductor 4350 Beltwood Pkwy South Dallas. TX 75244 (214) 450-0400 CIRCLE 323 ON FREE INFORMATION CARD GEnfe 401 North Washington Street Rockville, MD 20850 (800) 638-9636 CIRCLE 324 ON FREE INFORMATION CARD Haltek Electronics 1062 Linda Vista Avenue Mountain View, CA 94043 (408) 744-1333 CIRCLE 325 ON FREE INFORMATION CARD H&R Enterprises 21521 Blythe Street CanogaPark, CA 91304 (816) 703-8892 CIRCLE 326 ON FREE INFORMATION CARD Integrated Device Technology 2972 Stender Way Santa Clara, CA 95054 (408) 727-6116 CIRCLE 327 ON FREE INFORMATION CARD International Micro Electronics PO Box 170415 Arlington, TX 76003 (817) 561-2244 CIRCLE 328 ON FREE INFORMATION CARD your substrate pin. Thus, you can easily handle bipolar analog signals that go above and below ground. Your maximum clock frequency is 10 MHz, which means you can up- grade your potentiometer settings as often as 580 kHz or so. Their series wiper resistance is typically 400 ohms, and you're allowed a maximum potentiometer or wiper current of one milliampere. Be sure to see the data sheet for additional specs and timing details. LSI 1235 Walt Whitman Road Melville, NY 11747 (516) 271-0400 CIRCLE 329 ON FREE INFORMATION CARD Midnight Engineering 111 East Drake Road, Ste 7041 Fort Collins, CO 80525 (303) 491-9092 CIRCLE 330 ON FREE INFORMATION CARD Motorola 5005 East McDowell Road Phoenix, AZ 85008 (800) 521-6274 CIRCLE 331 ON FREE INFORMATION CARD National Semiconductor 475 Ellis Street Mountain View, CA 94043 (800) 632-3531 CIRCLE 332 ON FREE INFORMATION CARD SGS-Thompson 1000 East Bell Road Phoenix, AZ 85022 (602) 867-6259 CIRCLE 333 ON FREE INFORMATION CARD Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 CIRCLE 334 ON FREE INFORMATION CARD Texas Instruments PO Box 809066 Dallas, TX 75380 (800) 232-3200 CIRCLE 335 ON FREE INFORMATION CARD Xicor 851 Buckeye Court Milpitas, CA 95035 (408) 432-8888 CIRCLE 336 ON FREE INFORMATION CARD For our third contest this month, just tell me what you would do with one or more cascaded dual digitally controlled potentiometers. Making wavelets There's a brand-new math revolu- tion taking off that appears certain to profoundly change much of what electronics is and what it will be able to do. All the noise is over wavelet theory, an incredibly powerful new technique that promises to blow the A New wave in applied mathematics 8. Cipra, Science 24 Aug 1990, pp 858-859. New wave number crunching C. Brown E.E. Times, 5 Nov 1990, pp 31-34 Video compression using 3D wavelet transforms. A. Lewis, Electronic Letters, vol 26 no 6 pp 396-8, Non-orthogonal wavelet representations in relaxation networks. J. Daugman, New Developments in Neural Computing, pp 233-50. A theory for multiresolution signal decomposition. S. Mai la t. IEEE Transactions on Machine Intelligence, v11 -7 pp 674-93. Wavelet transformation in signal detection. F. Tuteur, 8th IFAC/IEORS Symposium, vol 2 pp 1061-5. Entropy reduction and decorrelation in visual coding. J. Daugman, IEEE Trans. Biomedical Engineering, vol 36 no 1 pp 107-14. Wavelet transformation in signal detection. F. Tuteur. ICASSP Speech Conference 38, vol 3 pp 1435-8. Complete discrete 2-D Gabor transforms, J. Daugman, IEEE Trans Acoustics S Speech, vol 36 no 7 pp 1 1 69-79. Dispersive noise removal in t-x space. Beresford-Smitii, Geophysics USA, vol 53 no 3 pp 346-58. Adaptive deconvolution by lattice filters. S. Persoglia, Bulletin ol Geophysics Theory, vol 27 no 107 pp 169-83, A critique of seismic deconvolution methods. A. Jurkevics. Geophysics, vol 49 no 12 pp 2109-16. Statistical pulse compression. E. Robinson. IEEE Proceedings, vol 72 no 1 pp 1 276-89. FIG. 5 — SOME KEY PAPERS on the new wavelet math theory which is now revolutionizing just about everything in electronics. 200-year-old Fourier analysis, syn- thesis, and transforms completely out of the water. Why worry about some obtuse new math theory? Well, first of all, because it's there. Second, because it's a sure fire winning topic for a school paper. And third, there's a lot of electronic doors about to suddenly get slammed in your face if you do not quickly pick up on exactly what wave- let theory is and what it can do for you. Fourier analysis is, er— better make that was, a method of giving you a second way of looking at and dealing with electronic signals. Be- sides the intuitive or "real-world'' time domain. Fourier techniques let you create a separate frequency do- main. Things not at all obvious in the time domain become quite clear when they are in the frequency do- main, and vice versa. For instance, a square wave in the time domain is just a signal that keeps bouncing up and down be- tween two levels. In the Frequency domain, that same square wave can be shown to consist of an infinite string of sine waves. Specifically, you can build up a square wave from its fundamental sine wave, one third its third harmonic, one fifth the fifth har- monic, and so on up the line. A few of the zillions of places that the frequency domain can become important include spectrum analysis, holograms, video-image compres- sion, music synthesis, side-looking radar, picture deblurring, etc. But the big problem with Fourier analysis is that everything was con- nected to everything else. Make even the slightest change, and you had to go back to square one and recom- pute everything. And while Fourier series is a great way to handle most of a square wave, it sure has troubles with the suddenly changing leading and trailing edges. What wavelet theory does is let you selectively mix and match wavelets that can both deal locally with sudden changes and globally with averages and backgrounds. You can thus selectively apply all your math power precisely where it will do you the most good, and do so with speeds and efficiencies that were to- tally unheard of with traditional Fourier analysis. What wavelet theory does is let you selectively mix and match wavelets that can both deal locally with sudden changes and globally with averages and backgrounds. You can thus selectively apply all your math power precisely where it will do you the most good, and do so with speeds and efficiencies that were to- tally unheard of with traditional Fourier analysis. Figure 5 shows a few of the newer key papers involving wavelet theory. Start out with the Science and E.E. Times overview summary stories be- fore you get into the heavy stuff. Let me know if you want to get into this any deeper. New tech literature The prices of bright-red visible laser diodes are starting to drop bunches, with a $45.00-in-singles unit now being offered by Haltek Elec- tronics. They are the newer, high-vis- ibility 630-nano meter wavelength, which is same as helium neon. Plan on $5.00 visible lasers within two years or so. New data books for this month in- clude that Special Purpose Linear Devices entry from National. Be sure to check out their LMC835 digitally- controlled graphics equalizer you'll find on page 1-227. Three other new data books are the Logic Databook from the Integrated Device Technology folks, a new Optoelectronics and Image Sensors from Texas Instruments, and an Integrated Circuits Data Book #33B Supplement from Burr-Brown. Static memory RAM specs cleverly disguised as baseball trading cards are being offered by SGS in an unusual promotion. Those are the same folks that previously gave you soup cans full of assorted free inte- grated circuits and soap boxes full of EPROM's. Three interesting new surplus cata- logs showed up in today's mail. They include Circuit Specialists , International Micro Electronics, and H&R Enterprises publications. Turning to my own products, for the fundamentals of digital integrated cir- cuits, be sure to check into my clas- sic TTLand CMOS Cookbooks. And. as you can tell from my nearby Synergetics ad, we've now got Hardware Hacker III and Ask the Guru III reprints available, as well as some new PostScript books. Also, a reminder that I do have this great new PostScript PSRT roundta- ble and library up on GEnie. You'll also find lots of Hardware Hacker and all of the Midnight Engineering re- 3 prints and other resources here. § Finally, I do have a new and free > mailer for you which includes dozens :< of insider hardware hacking secret re- ^ sources. Write or call for info. R-E 2 77 imj>|.)!l!H*JETTE Windows pains (and pleasures) JEFF HDLTZMAN Last month, we discussed how and why Windows is going to irrevocably change the PC in- dustry. Now let's look at how to put Windows to use today. You probably know that Windows can run in three different modes: Real, Standard, and Enhanced, Real mode should have been called Unreal mode, because it is so slow that it's unrealistic to expect anyone to use it. Real mode was created for marketing reasons, not technical ones. Win- dows will run on an 8088, and older applications will run under it. But you'd have to be crazy to want to. Even on a relatively fast (16- MHz) 386. real mode is much slower than the other two modes. Technically, Enhanced mode is the most sophisticated. It allows you to run regular DOS applications on- screen in graphics mode, in simu- lated text-mode windows, simulta- neously with regular Windows ap- plications. For example, before I got a real Windows communication pro- gram (Crosstalk for Windows, dis- co o o 9 80 ns SIMM 25GKx3 100 ns 1Mbit m>i 60 ns 1 Mbit imxi 30 ns 141256 ;:■:,■>;>:■ 30 ns 141256 2S3KH 100 ns 141256 2SGKxi 120 ns 14464 64Krt 100 ns 41264* WKx* 100fis EPROM I27C1000 i28K»a 200 ns 27C512 («.» 120 ns 27256 32K*a 150 ns 27128 16KjS 250 ns STATIC RAM I 62256P-10 32Kxe 100 ns I6264P-12 sk*8 120 ns 4*T Ml OH FED-EX ORDERS RECEIVED 6r SHIP VIA FED-EX ON SAT. MHterCanj VIS* "," UPS CASH COO MICROPROCESSORS UNLIMITED. INC t^o'^r (918)267-4961 Utj mimmUTl SrqfcMV Pain f^i» ir«i ivbKC -» i*v>gg S^CTiid riiil , i ■«ni'4BK>ii'nii|> , ii CIRCLE 61 ON FREE INFORMATION CARD amount of unbailable time I have wasted on soft font problems, I could have bought a PostScript printer. Windows has a mechanism for install- ing soft fonts, but soft-font installa- tion programs have a habit of really messing up WIN. INI. Several times the file has gotten so badly screwed up that I had to re-install Windows and some apps from scratch. And don 'l forget about dedicating 1 or 20 megabytes of space just to store the common sizes of half dozen fonts. That said, I've found Bitstream fonts to be the most reliable and of the highest visual quality. They are. however, expensive compared with the fonts sold by some vendors, and they're also limited as to special effects. The best package I've found for generating wild headline fonts and the like is MoreFonts, from Micro- Logic Corp. Flash: a copy of Adobe's ATM (Adobe Type Manager) just arrived. It is the equivalent of putting a PostScript font engine inside Win- dows itself, and because fonts are scaled as they are needed, disk stor- age is minimal — about a megabyte for 35 fonts, each of which can be scaled as needed to any reasonable size. Of course what you gain in stor- age space, you lose in processing speed: file printing and screen up- dates fake longer because fonts must be built as they are needed. To alleviate that problem. ATM re- serves a user-selected amount of memory for a font cache; figure at least 100K: 500K works, and for doc- uments with lots of font changes, a megabyte is better. The basic ATM includes Times, Helvetica, Courier, and Symbol fonts: at about $100 list. it's a steal. Note: ATM does its tricks with PostScript printers. LaserJets, and most common dot-matrix de- vices (Proprinter, Epson, etc.), but only with text; it can't print PostScript graphics. The Plus Pack adds 22 ad- ditional fonts, rounding out the typical PostScript complement. Windows applications I'd like to be able to operate ex- clusively in Windows, but cannot do so yet. There are extremely powerful programs in some areas, and a com- plete dearth in others. What I miss most is a decent file manager — -Win- dows' own file manager is awkward and limited. It doesn't even show the amount of free and used space on a disk drive. What's needed is a Win- dows version of Magellan, probably the best DOS file manager on the market. Even so, the basic Windows pack- age is surprisingly powerful. Several of the major applications — Write, Paint, Terminal— are as powerful as decent stand-alone packages of just a few years back. In a way, the Win- dows apps really are more powerful than the old stand-bys, because they work together, smoothly and effi- ciently. You can use Terminal to trans- fer files in the background while working elsewhere. You can create attractive drawings using Paint and paste them directly into write. Both Paint and Write will use whatever fonts you have installed on your sys- tem. I can see Windows 3.0 being used by anyone who doesn't need the utmost in power. The following are my picks for best Windows products. Word processing: Word for Win- dows. Allows multifile editing, multi- ple views into the same file via (what else) panes; a macro language as powerful as some versions of BASIC; efficient style sheets; the ability to load and save files directly in Word- Star, WordPerfect, and other for- mats; outlining; graphics import and printing. Could substitute for desktop publishing in many circumstances, but it is indisputably large and slow. Telecomm: Crosstalk for Win- dows. Extremely powerful script lan- guage for automated telecomm sessions. Runs beautifully in the background; minimize it to an icon, rn and it displays percent of transfer § complete, beeps when done. > Utilities: hDC's FirstApps. Pro- < vides real-time memory-usage dis- 3 play, ability to save complete - 79 ASK RE continued from page 16 ITEMS DISCUSSED trailer is hard enough even when you have all the documentation for the computer. To try doing the same thing with a completely unknown machine that has no supporting paperwork and Cso you say) no I/O ports strikes me as an exercise in futility. How you expect to control lights using a machine with no I/O ports is beyond me. And adding them to a machine for which you have no paper- work, and built by a company you can't get in touch with is a job only Sisyphus would want. If you've got the urge to build a home controller, you'll be much, much better off spending five hun- dred bucks or so for a PC clone and using that as the basis for the project. You'll have a known machine with real ports and languages available to write the software, I don't like to discourage anybody from doing whatever project they set their minds to, but yours is only slightly less difficult than striking a match on a bar of soap R-E CO o 2: o cc \3 LU D < 80 Get A Complete Course In ELECTRONIC ENGINEERING 8 volumes, over 2000 pages, including all necessary math and physics. 29 examinations to help you gauge your personal pro- gress. A truly great learning experience. Prepare now to take advan- tage of the growing demand for people able to work at the engin- eering level. Ask for our brochure giving complete details of content. Use your free information card num- ber, or write us directly. $99.95, Postage Included. Satisfaction guaranteed or money refunded. rVA/U 1/ Banner Technical Books, Inc. 1203 Grant Ave. Rockford, IL 61103 CIRCLE 67 ON FREE INFORMATION CARD • Adobe Type Manager ($99), Plus Pack ($198), Adobe Systems Incor- porated, 1585 Charleston Road, P.O. Box 7900, Mountain View, CA 94039-7900. (800) 83-FONTS. CIRCLE 41 ON FREE INFORMATION CARD • MoreFonts ($149.94), Micrologic Software, 6400 Mollis Street, Suite 9, Emeryville, CA 94608. (415) 652-5464. CIRCLE 42 ON FREE iNFORMATION CARD • ToolBook 1.0 ($395), Asymetrix Corp., 110 110th Avenue NE, Suite 717, Bellevue, WA 98004. (800) 624-8999, (206) 462-0501. CIRCLE 43 ON FREE INFORMATION CARD • Windows3.0 ($149), Word for Win- dows 1.1 ($495). Entertainment Pack ($39.95), Microsoft Corp., 17011 NE 36th Way, Box 97017, Redmond, WA 98073-9717. (206) 882-8080. CIRCLE 44 ON FREE INFORMATION CARD • Windows 3 Companion, Lori L. Lorenz and R. Michael O'Mara ($27.95), ToolBook Companion, Joseph R. Pierce, ($27.95), The Cobb Group/Microsoft Press, One Microsoft Way, Redmond, WA 98052-6399. CIRCLE 45 ON FREE INFORMATION CARD Windows environment and reload later. Good alarm clock too. Updates will provide file manager and Lap-Link type communications. Desktop Publisher: Ventura Pub- lisher 3.0 is pretty much a straight port from the GEM version; it pro- vides excellent table and equation editing, automatic counters, table of contents, indexing. PageMaker 3.01 merely adapts 3.0 for VVin3; PM 4 is due out around the time you read this, and is eagerly awaited. Illustration: Corel Draw has a mini- malist user interface that continues to amaze me with its power. I wish it did a better job with small font sizes, displayed a visible grid, did arrays, and allowed symbols. Screen Capture: My unabashed favorite screen-capture and print pro- gram is Pizazz Plus. The current ver- sion only partially supports Windows: full Windows support should be out by the time you read this. Development Environment: ToolBook, For user-interface pro- totyping, there's nothing like it. Ex- tremely powerful and fun. Games: I'm not much of a gamester, • FirstApps ($99.95), hDC Comput- er Corporation, 6742 185th Avenue NE, Redmond, WA 98052. (206) 885-5550. CIRCLE 46 ON FREE INFORMATION CARD • Crosstalk for Windows ($195), DC A, 1000 Alderman Drive, Alpha- retta, GA 30202-4199. (404) 442-4000. CIRCLE 47 ON FREE INFORMATION CARD • Ventura Publisher Windows Edi- tion ($895), Ventura Software, Inc., 15175 Innovation Drive, San Diego, CA 9212. (800)822-8221. CIRCLE 4B ON FREE INFORMATION CARD • Corel Draw ($XXX), Corel Sys- tems Corporation, 1600 Carling Ave- nue, Ottawa, Ontario, Canada K1Z 8R7. (613) 728-8200. CIRCLE 34 ON FREE INFORMATION CARD • Pizazz Plus ($149), Application Techniques, Inc., 10 Lomar Park Drive, Pepperell, MA 01463. (508) 433-5201. CIRCLE 35 ON FREE INFORMATION CARD but I've seen a few Windows games that are attractive. Microsoft has re- leased an Entertainment Pack with a version of Tetris. several card games, a screen blanker, and more. Also, I've collected a few shareware games (Chess, Checkers, a Tetris clone) that CJI post on the R-E BBS. Books: Microsoft's Windows User's Guide is infinitely better than previous versions, but is really a refer- ence guide. The Windows 3 Compan- ion provides a view from the user's perspective. For ToolBook program- ming, the ToolBook Companion in the same series is quite useful. Conclusion If I complained about Windows, it's only because it's worth complaining about — I see plenty of bad software that isn't worth the magnetic ink it's printed on. In spite of my complaints, I really like Windows. The program is not perfect, but it got a whole lot better with version 3.0. This version is more than just a passing fad be- cause it represents not just a new way of doing things, but a better way. Try it — you really will like it. R-E lln'll'lll^y.) The Boston Sound: Part II LARRY KLEIN Last month we traced the inter- twined history of some of the important New England-based loudspeaker manufacturers. Without exaggeration, it can be said that those companies established new technical standards for home loud- speakers. In general, their products were smoother, had wider range, and had far less coloration than either previous designs or those of most of their competitors on the West Coast. Although I covered only the most prominent New England companies and designers, I'm sure that there are others who made contributions that also advanced the state of the speak- er art. As discussed in last month's col- umn, one of today's leading manufac- turers of high-quality speaker sys- tems is Boston Acoustics. Last fall I had the pleasure of visiting BA's new, highly automated plant and spending the day with the president of the com- pany, Andy Petite. In the course of our conversations, we touched on a number of issues and matters that are of concern to anyone interested in how loudspeakers are designed and manufactured — and particularly what makes them sound good. What follows is a random selection of Andy's views, somewhat condensed and paraphrased. • As you know, the crossover net- works found in today's speakers range from the incredibly complex to the surprisingly simple. We try to de- sign the simplest possible crossover that will do the job in a particular sys- tem. Many of the components that you see in complex crossovers are in there to compensate for the deficien- cies of the system's drivers. For ex- ample, if you design a woofer with a smooth response at the crossover- frequency area and above — which is the right thing to do with respect to overall performance — you can con- siderably si mplify your crossover net- work. Not only does that save money, but it also minimizes power losses and provides a smoother impedance curve for the amplifier to drive. • In production, our assembled crossovers are checked against a ref- erence network to a tolerance of ±0.5 dB. Aside from helping ensure the frequency performance of the system as a whole, that procedure eliminates the crossover assembly as the cause if system response is not up to spec in the final checkout. That's important because, while it's easy to replace drivers if necessary, it's a real pain to get to and fix a crossover once it's finally installed in an enclosure. • We usually prefer to use acoustic- suspension woofers rather than bass-reflex or vented designs for two reasons: The woofer in a vented sys- tem is inherently uncontrolled below its low-frequency cutoff. The very low frequencies generated by turntable rumble and tone-arm resonances can cause excessive cone excursions in the infrasonic area and, therefore, in- termodulation distortion at audible frequencies. Of course, as LP's fade from the marketplace, the sonic prob- lems produced by the equipment that is used to play them will also disap- pear. Another difficulty has to do with the FIG. t — BOSTON ACOUSTICS' SW10 powered sub woofer features a 100- watt in- ternal amplifier with electronic crossover. way a woofer ages. Its suspension becomes more compliant over time, which can mistune a critically tuned vented system. In contrast, an acous- tic suspension design is relatively im- mune to bass-response changes through woofer aging. Both of those problems are a lot less severe these days, although we question how well small and/or inexpensive vented sys- tems react to the strong low bass found on many CD's, • When it's technically and econom- ically feasible to do so, there's a defi- nite advantage in directly powering a woofer or subwoofer. By elec- tronically controlling the charac- teristics of the signal fed to the woofer you can easily achieve very low frequency crossovers, response curves, and very steep rolloffs that would be quite impractical with pas- sive inductive/capacitive networks. That allowed us to use a vented sys- tem for our powered subwoofer — which has the advantage of reduced excursion at low frequencies com- pared to an acoustic suspension — without running into the infrasonic problems I just mentioned. You can also avoid many types of acoustic problems with non-powered vented designs by designing them for a good low-bass response. If the cut- off frequency is made low enough, the speaker will be controlled prop- erly down to the lowest musical fre- quencies. • There's a common assumption that the larger the woofer in a system, the better the bass. But for a large woofer to be effective it must be in- stalled in a large enough enclosure. For example, if you put a 12-inch woofer in a t.5-cubic-foot enclosure, the small volume of the enclosed air raises the system resonance, and the bass response decreases. To restore m the bass you have to add more mass S to the cone, and then use a heavier > magnet to maintain efficiency. That is < not a very cost-effective process. £ The only advantage of a large cone 2 81 LEARN VCR CLEANING/MAINTENANCE/REPAIR EARN UP TO $1000 A WEEK.WORKING PART TIME FROM YOUR OWN HOME! THE MONEY MAKING OPPORTUNITY OF THE 1990'$ IF you are able to work with common small hand tools, and are familiar with basic electronics (i.e. able to use voltmeter, understand DC electronics). . . . IF you possess average mechanical ability, and have a VCR on which to practice and learn. . . .then we can teach YOU VCR maintenance and repair! FACT: up to 90% of ALL VCR malfunctions are due to simple MECHANICAL or ELECTRO-MECHANICAL breakdowns! FACT: over 77 million VCRs in use today nationwide! Average VCR needs service or repair every 12 to 18 months! ViejO 5 40D PAGE TRAINING MANUAL (over 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 into you'll need regarding the BUSINESS-SIDE of running a successful service op- eration! FREE | NFr j R MATI0N CALL TOLL-FREE 1-800-537-0589 Or write to: Viejo Publications Inc. 5329 Fountain Ave. Los Angeles, CA 9C029 Dept. RE CIRCLE 189 ON FREE INFORMATION CARD ~\ "\t)fc!£& ►«£g& 82 pSl& w BE* FIG. 2— BOSTON ACOUSTICS' 380 is the smallest 8-inch, two-way, flush-mount speaker system available. woofer is a somewhat higher max- imum output level — assuming that it's installed properly in an adequately sized box. If you can get the loudness levels you want with smaller cones, you are better off using them — in pairs if necessary. Using small cones in pairs has definite advantages. • Some of the basic enclosure ground rules change when you're dealing with car-stereo speakers or speakers meant to be flush mounted in a wall. In both cases, we design the woofers with a fairly stiff-suspen- sion — which makes them more rug- ged — because their free-air reso- nance is not shifted upward to any degree by the mounting. In general, there is not a significant variation in the rear loading seen by woofers in most car installations. We get a very good correlation between tests in a car door or rear package shelf and tests done with the woofer mounted on a simulated infinite plane baffle — in other words, a large sheet of plywood. • Over the years I've observed that there is a real dichotomy between the views of the empirical and the the- oretical speaker designers. For ex- ample, for years the academic theorists would give loudspeaker-de- sign papers at various Audio Engi- neering Society conventions. Those were frequently greeted by snickers from the designers in the room, be- cause it was clear that the theoreti- cians had not tried out their ideas by designing and building systems. A fa- vorite example: One particular pro- fessor of acoustics had for years been giving papers on phase-correct crossover networks. At one point he and a grad student decided to build a speaker system based on the pro- fessor's theories. It turned out that the system didn't work very well be- cause real-world drivers have a com- plex impedance, quite unlike the resistors on which the design calcula- tions had been based. The next year his paper was based on his work with real world drivers. • Except when dealing with au- diophiles. speaker designers have al- ways had a tough job satisfying interior decorators, architects, and others who would prefer that speak- ers be heard but not seen. Electronic woofer control has made possible substantial reductions in cabinet size while still realizing adequate bass. However, the laws of physics put a limit on how loudly a very small woofer can play and how low it can go even with everything optimized. Built- in wall speakers and subwoofer/sat- ellite systems are two variable solu- tions to make speakers invisible, or at least unobtrusive in the home or workplace. A final word: Andy Petite 's views on speaker design should be par- ticularly interesting to anyone who likes to know the technical thinking and design process behind commer- cial audio products. As the proof of the pudding is in the eating, so too the test of any design approach is the performance of the product. To my ears. Andy's thinking — and design approach — make an exceptional amount of sense. R-E CIRCLE 108 ON FREE INFORMATION CARD How to build a high-paying career, even a business of your own, in computer programming. baud internal modem, 640K RAM, disk drive, monitor, and invaluable programming software — BASIC, Pas- cal, C, and COBOL — all yours to keep. You get the experience and the know-how, the computer and the software to get to the heart of every programming problem, design imagi- native solutions, then use your choice of four key computer languages to build original, working programs. 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Then, rounding out your training, you use your modem to "talk" to your instructor, meet other NRI students, even download pro- grams through NRI's exclusive pro- grammers network, PRO NET. Your career in computer programming begins with your FREE catalog from NRI. For all the details about NRI's at-home training in Computer Programming, send the coupon today. Soon you'll receive NRI's fascinating, information- packed, full-color catalog. Open it up and you'll find vivid descriptions of every aspect of your NRI training. You'll see the computer system included in your course up close in a special, poster- sized foldout section. And, best of all, you'll find out how your NRI training will make it easy for you to build that high-paying career— even a business of your own— in computer programming. You master today's hottest computer languages, gaining the skills you need to build programs for a wide variety of real- world applications. With your personal NRI instructor on call and ready to help, you use your computer and software to actually design, code, run, debug, and document programs in BASIC, Pascal, Send for your NRI catalog today. If s yours, free. If the coupon is missing, write to us at the NRI School of Computer Program- ming, McGraw-Hill Continuing Educa- tion Center, 4401 Connecticut Avenue, NW, Washington, DC 20008. IBM is a Registered Trademark of the IBM Corporation School of Computer Programming McGraw-Hill Continuing Education Center 4401 Connecticut Avenue, NW Washington, DC 20008 YES! Please rush me my FREE catalog describing NRI's at-home training in Computer Programming. m NAME (please print) AGE ADDRESS Crry/STATE/ZIP Accreted Member National Home Sludy Council 5413-031 m oo J} c > ID -< tO CO 85 R-E Engineering Admart Surface Mount Chip Component — ^ Prototyping Kits- Only CC-1 Capacitor Kit contains 365 pieces, 5 &a. of every 10* value from 1pl 10 -33^1 OR-1 Resistor Kil co mams 1 540 pieces ; 1 ea. ol every 5% value Irom 10ft to 1 meo,n Sizes are 0305 and 1206 Each kit is ONLY S4995 and available for Immediate One Day Delivery! Order by toll-free phone, FAX, or mail. We accept VISA, MC, AM EX. COD, or Pre-paid orders. Company RO/s accepted with approved credit. Call for free detailed brochure. f COMMUNICATIONS SPECIALISTS, INC. ' tit. West Taft Ave ■ Orange. CA 926654295 ' Local (714| 998-3021 • FAX (714) 974-3420 Entire USA 1-800-854-0547 Rales: Ads are 2Wx2%". One insertion $995 each. Six insertions $950 each. Twelve insertions $925 each. Closing date same as regular rate card. Send order with remittance to Engineering Admart, Radio-Electronics Magazine, 500-B Bi-County Blvd., Farmingdale, NY 11735. Direct telephone inquiries to Ariine Fishman, area code-1-516-293-3000, FAX 1-516-293-3115. Only 100% Engineering ads are accepted for this Admart. FCC LICENSE PREPARATION The FCC has revised and updated the commercial license exam. The NEW EXAM covers updated marine and aviation rules and regulations, transistor and digital circuitry. THE GENERAL RADIOTELEPHONE OPERATOR LICENSE - STUDY GUIDE contains vital information, VIDEO SEMINAR KITS ARE NOW AVAILABLE. WPT PUBLICATIONS 979 Young Street, Suite E Woodburn, Oregon 97071 Phone (503) 981-5159 Dept. 50 MIDI PROJECTS > i BP182— MIDI interfacing enables any so equipped instruments, regardless of the manufacturer, to be easily connected to- gether and used as a system with easy com- puter control of these music systems. Combine a computer and some MIDI instru- ments and you can have what is virtually a programmable orchestra. To get your copy send $6.95 plus $1.25 for shipping in the U.S. to Electronic Technology Today Inc., P.O. Box 240, Massapegua Park, NY 11762-0240. CIRCLE 187 ON FREE INFORMATION CARD CIRCLE 190 ON FREE INFORMATION CARD 00 O z O c r- o _! -I 6 STAYING WITH DOS: GETTING THE MOST FROM YOUR COMPUT- ER WITHOUT CHANG- ING YOUR OPERATING SYSTEM; by Dan Gookin. Ventana Press, P.O. Box 2468, Chapel Hill, NC 27515; Tel: 919-942-0220; Fax: 919-942-1140; $22.95. Even though today's so- phisticated computers and applications software are increasingly demanding, there's a good chance that CIRCLE 31 ON FREE INFORMATION CARD you can get by with DOS, and not have to upgrade to an expensive new operat- ing system. This book can help you decide whether you should stay with DOS as it is, use other products to enhance it, or move on to a new operating system. It emphasizes that DOS can remain a viable alter- native to OS/2 or Unix, and explains how users can get more memory, more speed, better graphics ca- pabilities, and even do multi-tasking and network- ing with their old operating system. A chapter on Win- dows 3.0 and other graph- ical user interfaces pro- vides a detailed overview of how to use those to make DOS perform like the new- er, more powerful operat- ing systems, without hav- ing to invest money and time in buying and learning to use a new operating sys- tem. Convenient check- lists help readers evaluate their needs, and appen- dices provide detailed buy- ing information on new products that help boost the speed and power of DOS. ECG Audio and Video •*■• CIRCLE 32 ON FREE INFORMATION CARD ECG AUDIO AND VID- EO: Replacement Parts & Service Aids; from Philips ECG; 1025 West- minster Drive, Williams- port, PA 17701; Tel: 800- 526-9354. Philips ECG's expanding audio and video product line — including a larger se- lection of VCR mechanical replacement parts and re- placement RF modu- lators — is described in the second edition of this cata- log and cross-reference guide. Several previous ECG publications have been consolidated in this one book, which presents more than 270 products. The catalog contains pic- torial selector guides, specifications, cross-refer- ence sections, and related replacement information on a variety of VCR modu- lators, opto-sensing de- vices, pinch rollers, idler wheels, assemblies and tires, individual belts and belt kits, and VHS/Beta re- placement heads. Also fea- tured are service aids for making fine adjustments to tape equipment, such as audio/video test cas- settes, lubricants, and cleaning materials. The cat- alog cross references 31 popular VCR brands and more than 2400 industry model/part numbers. R-E 86 MARKET CENTER FOR SALE DESCRAMBLERS. All brands. Special: Combo Jerrold 400 and SB3 $165.00. Complete cable de- scrambler kit $33.00. Complete satellite de- scrambler kit $45,00. Free catalog. MJM INDUSTRY, Box 531. Bronx. NY 10461 -02O8. ENGINEERING software, PC/MS DOS. 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, BSOFT SOFTWARE, 444 Colton Rd., Columbus, OH 43207. RESTRICTED technical information: Electronic sur- veillance, schematics, locksmithing, covert sci- ences, hacking, etc. Huge selection. Free brochures. MENTQR-Z, Drawer 1549, Asbury Park, NJ 07713 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 52. CBC INTERNATIONAL P.O. BOX 31500RE, PHOENIX, AZ 85016 CABLE TV converters: Jerrold, Oak, Scientific At- lantic, Zenith S many others. "New MTS" stereo add-on: mute & volume. Ideal for 400 and 450 owners! 1 (800) 826-7623, Amex, Visa. fvVC accept- ed. B & B INC., 4030 Beau-D-flue Drive. Eagan, MN 55122 TUBES, new, up to 90% off, SASE, KIRBY, 298 West Carmel Drive, Carmel, IN 46032. PROGRAMMABLE stepper motor drive & control for under $100, IBM PC/XT compatible. Com- modore 64, or other with 25 pin parallel port. PCB, interface & software. Send for detailed literature to: MASE, R.D. #2 Box 166, Mohrsvilie, PA 19541. CABLE TV converters and descramblers. We sell only the 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) 234-0726. PRINTED circuit boards etched & drilled. Free deliv- ery. K& F ELECTRONICS, INC., 33041 Groesbeck, Fraser, Ml 48026. [313] 294-8720. Quality Microwave TV Antennas WIRELESS CABLE - IFTS - MMDS AnuHur TV Ultra High Gain SIMtiH ■ IiimiMe 1.9 tt Z.7 Gin. • 36-Criarmel System Complete SI 49.95 • ■ 2 Cruraicl System Complete S1 14.95 • Call 01 writ! (SASE) (w "FREE" Catalog PHILLIPS-TECH ELECTH0NICS P.O. Bm 8533 . Scottsdale, AZ B525Z ■ (602) 947-7700 IJ3.M Credit ill prime order!) WARRANTY MsslirCard • Vlu ■ COD'i ■ Qurrnrr Pricing FREE catalog: Save hundreds on sought after elec- tronic, electro mechanical, and computer related hardware and components — including hard-to-find items. Call toll free: 1 (800) 776-3700. AMERICAN DESIGN COMPONENTS/Dept. 119-021. 815 Fair- view Avenue, Fairview, NJ 07O22. ARTWORK created for use in printed circuit board production from your engineering schematics. Pro- fessional quality hardcopy, Gerberfile, or Photoplot- ter outputs. Reasonable rates. Send lor details to: JTD ENGINEERING, 10628 Grandview Place, Alta Loma.CA 91701. TUBES: "oldest," "latest." Parts, schematics SASE for lists. STEINMETZ, 7519 Maplewood Ave., RE Hammond, IN 46324. CABLE TV converters & descramblers for Jer- rold and Scientific Atlanta. Low prices, one year warranty. We Ship COD. BAY STATE ELEC- TRONICS, PO Box 103, Boston, MA 021 88.1 (800) 359-9806. SURVEILLANCE telephone, monitor room con- versation, S175.00. Monitor room and telephone conversations, $275.00. Dialer, calls you whenever telephone is used, $305.00. Catalog, $3.00 to: LIS- TEN ELECTRONICS, 603 Elgin. Muskogee, OK 74401. 1 (800) 633-8277. FREE CATALOG FAMOUS "FIRESTIK" BRAND CB ANTENNAS AND ACCESSORIES. QUALITY PRODUCTS FOR THE SERIOUS CB'er. SINCE 1962 FIRESTIK ANTENNA COMPANY 2614 EAST ADAMS PHOENIX, ARIZONA 85034 CABLE descramblers (Jerrold) from S4O.O0. Toconn VIP test chip Fully activates unit. Also Zenith lest board. Fully activates Z-Tacs. $50.00. Call (213) 867-0081. T.V. notch filters, surveillance equipment, brochure $1.00. D.K. VIDEO, Box 63/6025. Margate, FL 33063. (305) 752-9202 WIRELESS CABLE RECEIVERS 1.9 TO 2.7 GHz JO LH KAKAuu'LlL U I bri aYIiltM 5lfj 90 30 CH ROD ANTENNA SYSTEM 5193.90 30 CH CRYSTAL CONTROLLED SYSTEM S?9* 95 SUN MICROWAVE INTL. INC. SEND $1.00 FOR P B OX • 31 522 CATALOG ON THESE PHOENIX. AZ. JSM! AND OTHER FINE ISO?) 210-0610 VIDEO PHODDCTS QUANTITY DISCOUNTS RADIO tubes, parts Extensive listings. $1.00 (re- fundable). DIERS, 4276-E6 North 50th Street, Mil- waukee, Wl 53216-1313 u CABLE TV brokers and distributors high volume of descramblers Jerrold SB-3 refurbished or as is, con- verters Jerrold models DRX-400, JRX and hand remote control (no Canada sales for descramblers). Affitech. ask DANIEL PERREAULT (514) 656-9150. KITS, MC68701 programmer S135.00, Morse code keyboard $75.00. ten meter FM conversion S25.Q0. SINGLE CHIP SOLUTIONS, Box 680, New Hartford. CT 06057-0680. COMMUNICATIONS SECURITY ASSOCIATION — Electronic Surveillance, countersurveillance, communications security topics — membership in- formation — POB 7069, Gaithersburg, MD 20898. (301) 309-3731. NEW devices: proximity switch, static snooper, per- sonal defender, laser supplies, bug snooper, PC interfaces and more. Catalogue $2.00. BAUER, 35 Soucy. Oelson, Quebec, J0L 1G0. H0CM 7S . . . * 79 7S...'119 ss...'Z29 77...M49 87. ..'269 A NEm Modal AS ... *579 ▼ ■■g/CELVW EM™* 5_!7 Fuitchild Ay. amm Pliinvtsw, NY 11 B0 3 (516) 349-7620 1(800) 645-9212 PROTOQUICKZ6, single board computer with pro- totype area. $69.00. SOFTWARE SCIENCE, 3750 Roundbottom Road, Cincinnati, OH 45244. (513) 561-2060. CABLE TV DESCRAMBLERS! BARGAIN HEADQUARTERS! •JERROLD 1 " •TOCOM -HAMLIN •OAK 'ZENITH •SCIENTIFIC ATLANTA 6 month warranty! We ship C.O.D.! Lowest retail/wholesale prices! FREE CATALOG: Global Cable Network 1032 Irving St. Suite 109 S.F., CA 94122 NO CALIFORNIA SALES!!! ORDER TODAY! 800-327-8544 FREE catalogue. Computers. Electronic parts and kits. Filters, amplifiers, power supplies. Radio Shack Dealer. MCDOWELL ELECTRONICS, Box 1206. Brewton. AL 36427. (205) 867-8805. ROBOTICS software, PC.'MSDOS. Explore com- puter vision, sonar sensing. Free brochure. ROBOTS ETC, Box 122. Tempe, AZ 85280. TEST equipment pre-owned now at affordable prices. Signal generators from $50.00, os- cilloscopes from $50.00, other equipment, 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. Vi WATT resistor kit 161 values 5 each in its own labeled envelope. All in a neat file box. 5 more each of popular values. 990 resistors. S19.95 shipped. DELTA DISTRIBUTORS, Box 87, E. Derry. NH 03041 . 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 C.O.D. telephone orders accepted (800) 648-3030 SO Day Guarantee (Quantity Discounts) 8 A.M, to 5 P.M. C.S.T. CLOSED WEEK- ENDS. Send self -ad dressed Stamped enve- lope (60c postage) (or Catalog. imiDLUEST P.O. Ben 5000 No lllfnois Orders Accepted Carpenlersville. IL 60110 m 03 3 C > 3 87 MOVIE VIEW SALES Cable T.V. Converters Descramblers / Low Prices PO Box 26 ■ Wood Dale, IL 60191 (708) 766-5222/Fax (708) 766-5269 Call CST Mon.-Fri. - 9-5 / Sat.-10-2 JERROLD - SCIENTIFIC ATLANTA OAK ■ ZENITH ■ HAMLIN • PIONEER Converter Only • Hand Helds Ch. 3 Filters • 3 Ft Jumper Cabte [J] VISA/Mastercard ED COD. til Friendly Knowledgeable Service Si 10 Yrs, Experience S] 6 Mos. Warranty (NO ILLINOIS SALES) CB DX 1990'S, get more out ot your radio. CBR, Box 212. Rochelle Park, NJ 07662. Catalog. GREAT buys, Surplus prices, DC motors. PS-13VDC-20A, light chasers, liber optics, transfor- mers, scope probes, vacuum pumps, LSASE, FER- TIK'S, 5400 Ella, Phila.. PA 19120. REMOTE CQNTFlpL KEYCHAIN1 :/:■'.: Complflte w/mini-tronsmttlflf and +S vdc RF receiver Fully ssiemUed including plans : . : :|1o build your.own auto alarm . Quantity discounts available. CO/I r\c Cbeck.Viaa or fvl/C:; ^^r.yO Add S 3 shipping VESiTECT IMC, BOX 5442, SO.SAN FH AM CA; 94GGG (415) 872^128 .., Fax .{41 S) 872-2635 Cable TV Descramblers If you find a better deal, we'll better our deal. 'Jerrold 'Tocom "Hamlin 'Oak 'Scientific Atlanta 'Zenith Ask about our extended warranty program. COD, Vlso, M/C welcome. Free Call - Free Catalog. Video Tech 800-562-6884 3702 S. Virginia St., Ste. 160-304 Reno.NV 89602. TOCOM VIP converters w/remote from $279.00. Tocom super chips turn on everything. $69.00 each. Phone (219) 935-4128. PHOTO FACT folders under #1400 $4.00. Olhers $6.00. Postpaid. LOEB, 414 Chestnut Lane. East Meadow, NY 11554. FM 2 -way. C 6. 'amateur, scanners, radar detec- tors, auto alarms, catalog S1.00, RAYS, PO Box 14862, Fort Worth, TX 76117. VIDEO game circuil boards, some working, all good (or parts. (Processors, eproms. ETC.) $3.00 and up. Call (301) 233-2600. Ask (or BARRY or CHUCK. TV troubleshooting solutions. 450 solutions by area and components. Symptom remedy make model Sams rel. Save time, you'll love il. Send $24.50 to PHASE CONTROL ENG., Box 222. Chanhassen, MN 55317. TOCOM VIP lurn on chip that does il all, $40/1, S35/50 comes With instructions (419} 475-9453. PLANS AND KITS MINIATURE FM transmitters! Tracking transmitters! Voice disguisers! Bug delectors! Phone Devices! More I Available in kils or assembled! Catalog $2.00: XANDI ELECTHONICS, Box 25647, Dept. 60N, Tempe, AZ 85285-5647. C ATA LO G : h obby/broadcast i ng/ H A M/CB : Cafcf e TV, transmitters, amplifiers, surveillance devices, computers, more! PANAXIS, Box 130-F2, Para- dise, CA 95967. CB Tricks II book. Power amplifier design and theo- ry, UHF CB tune ups. Send $1 9.95 MEDICINE MAN CB, PO Box 37, Clarksville, AR 72830. DESIGN your own custom circuits with our user friendly electronic engineering software. IBM and compatibles. Commodore 64, and 128. Free infor- mation. Write or call today! WEASELGRAPHICS, PO Box 51697, Riverside, CA 92517-2697. Phone 1 (800) 356-8113 Visa/Mastercard. O o LU _l UJ O Q < CABLE TV TB-3 (Tri-Bi) or SA-3 Quantity Prices 10 20 $48. $43 Each 50 Each 100 $*59a S|)g3 Each Each Hours open 10:00 am to 4:00 pm Eastern time Minimum order 5 units 55.00 ea. Dealers wanted. We ship COD. King Wholesale 1-800-729-0036 Fax number 6173400053 'Wo one beats the King's prices!" DESCRAMBLERS Try the KzhiiXitifiirs bulletin board system (RE-BBS) 516-293-2283 The more you use il the more useful il becomes. We support 300 and 12D0 baud operation. Parameters: 8N1 (8 data bits, no partly, 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 en H-E with the SYS0P. RE-BBS 516-293-2283 PCfTV interface - RGB to TV/Video /VCR. Switcha- ble between PC and composite video inputs. Chan- nels 3 or 4, RF output. Complete PC card kits $59.95 PC board only $19.95. INNOVONICS CORP., 9 Bartlet St., Dept. 36, Andover, MA 01810. POWERFUL single-chip FM room Iransmitter. size of a postage stamp transmils to any FM radio up to one mile away. Complete kit $19.95 postpaid. HERTZ MICRODEVICES, Box 41771, LA, CA 90041-41771. SURVEILLANCE — Audio/video/infra-red/laser equipment. Industrial or private. 500 item catalog $7.00. SECURITY SYSTEMS, 3017G Hudson. New Orleans, LA 70131. TRANSMIT VCR to any set in house. Inexpensive. No construction. Complete instructions. $4,00. VENTURA, Box 377. Beverly, MA 01915. BUILD from easy-to-follow schematics: audio mix- ers/equalizers (stage, studio, business, home. basic to sophisticated), feedback controllers, active filters, guitar super-tuzz box, loudspeaker en- closures (including car/van), power supplies, more. vSSE reliability. Send $5,00 (or descriptions. Rea- sonable prices VON SPRECKEN SOUND ENGI- NEERING, Dept. B, Box 1315, Clinton, MS 39060. CABLE DESCRAMBLERS OAK M35B COMBO S33.9S Jerrold, Zenith, Hamlin, Set Atlanta, Pioneer & MORE! OUR PRICES ARE BELOW WHOLESALE! CABLEH-PLU8 14417 Chase St. #481-A Panorama Cily, CA 91402 1-800-822-9955 • Other Into. 1-818-785-4500 MO CALIF. SALES - DEALERS WANTED DESCRAMBLING, new secret manual. Build your own descramblers (or cable and subscription TV, Instructions, schematics lor SSAVI, gated sync, sinewave, (HBO, Cinemax, Showtime, UHF, adult) $12.95. $2.00 postage. CABLETRONICS, Box 30502 R, Bethesda, MD 20824. AMAZING device disables any remote keychain car alarm via radio! Cheap one evening project. Sell to car "Repo" companies for hundreds $ profit! Or just fool friends and neighbors. Complete theory and plans $12.95. HUMAN MOVEMENT SYSTEMS, 131-30 234 St., Rosedale, NY 11422. BUILD a remote controlled video switch. Send $1 00 for schemau'e. D. SCHWEIGART, PO Box 1352, Wellsville, NY 14895. MIDI and music accessories, plans, kits, and as- sembled, catalog $1.00, M-SEQ, Box 231233, San Diego, CA 92194. REMOVE copy protection distortion while viewing rental movies. Complete plans using $5-10 in parts. Send $9.95 and SASE to AUTOSOLVE, PO Box 3997, Oak Park, IL 60301. AUDIO! Plans/products - inexpensive, profession- al, amps, mixers, more! Literature/cassette -$3.00 1 DAViSOUND, Box 521, Newberry, SC 29108. INVESTIGATORS, experimenters — Quality new plans. Micro and restricted devices. Free catalog. Sell addressed stamped envelope required KEL- LEY SECURITY INC., Suite 90, 2531 Sawtelle Blvd.. Los Angeles, CA 90064. FREE CATALOG! 1-800-648-7938 For all information 1-702-362-9026 JERROLD HAMLIN OAK ETC. CABLE TV DESCRAMBLERS • Compare our low Low Retail Prices! ' Guaranteed Prices & Warranties! • Orders Shipped Immediately! REPUBLIC CABLE PRODUCTS INC. 4030 Paradise Rd. fflS Depl. RE-90 Las Vegas, NV 89109 — - KITS — alarms, games, and test equipment. Send $1.00 lor catalog. RAKJAB, PO Box 1875, Apopka. FL 32704. LASER lighting entertainment systems and ac- cessories. Create 3-dimensional laser light shows with these professional secrels! Electronic and me- chanical designs for all budgets! $20,00. MILLEN- NIUM, 229 McAfee. Thousand Oaks, CA 91360, (P&OTIVU 1/idtopkont in a Chip STILL FRAME TV PICTURE TELEPHONE TRANCEIVER KIT Sands Slow Scan TV plcturanovtr The phont Hnti In Twtlvo Soconda Capiiirss any TV Camera. i VCR, NTSC VldQO output and hold AlJtQ an d Mods bTIowji hand rocolvo. Display* v fraa sand on any TV ic CMlp R • plac«f 1 SO SS| Dips | ^n I AVAlQ tm] devh b cotnnt ho -rfw hDT*W KISV TO GCtkLMSAIE. hl>S of Grey Scale htmcmmw ««"«>«* ^ArvBi: i)e> ri«o bets ahi rftftjMD for TV FAX t ;i l Lin* Us* VCH Mod 2QQ x &I&S 1 High Bet. liasjiu M,0M Pi SOl* "**** ' OIH TO MXBOCAajtrTE «QW«Q Vld»ophon» Chip and Schema He AD. DRAM, D-R»g. PC Boird (BARE) 50 R*l. Cap, Diotfi Cablnat (uncut) Pow*r Pack KIT PRICE; ASSEMBLED 5 Box 1 1 1 48 I Del Rey. CA 90292 METAL project boxes - 50% Off! Huge selection. Plus storage capacitors, amplifier kits, electronic parts. Free catalog. SCC, Box 551 RE, Dublin. OH 43017. PCB and schematic CAD software. Easy mullilayer rubberband zoom pan and more. CGA EGA IBM compatibles. $195.00 NUMBER ONE SYSTEMS, 10S65 Bluebird Street, Coon Rapids. MN 55433. Demo Disc. (612) 757-8584. CABLE TV "BOXES" Converters — Descrambters Remote Controls— Accessories * Guaranteed Best Prices * * 1 Year Warranty - C.O.D.'s * * Immediate Shipping * * FREE CATALOG * Call or Write TRANS-WORLD CABLE CO. 1 2062 Southwest 1 1 7th Court, Suite 1 26 Miami, Florida 33186 1 800442-9333 CIRCLE 30 OH FREE INFORMATION CARD PRO 400 95 69 AC,' DC VOLTAGE AC.'DC CURRENT DIOOE TEST Stock Na LOGIC TEST 990092 LEE TEST GOOD BAD 5 FREO RANGES 5 CAPACITANCE RANGES LOW BATTER V Warning CONTINUITY TEST.'BUZZEI TRANSISTOR CHECKER 20 mhzFREQ COUNTER 3 KELVI N Elmiroraes 30 DAY MONEY- HACK GUARANTEE 1 □ □ ■■ US j 7 Fa^cfuld Ave.. Plainview. NY tiaoa (516)349-7620 1(809)645-9212 FAX (516) 349-7830 SURVEILLANCE transmitter kits! Four models of each; leie phone, room, combination telephone/ room transmitters tune from 65 to 305 MHz. Catalog with Popular Communications and Popular Electronics book reviews ol "Electronic Eaves- dropping Equipment Design," $1 00. SHEFFIELD ELECTRONICS. 7223 Stony island Ave.. Chicago, IL 60649-2806 DAZER II personal protection device! Plans $8.00. Lasers! Transmitters! Detectors! More! Kits or as- sembled! Catalog $2.00. QUANTUM RESEARCH, 16645-113 Avenue, Edmonton, Alberta T5M 2X2. SATELLITE TV 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. Volume 4 - Repair $99.95 Volume 7 - 032/Hackjng $54.95. Cable Hacker's Bible - $34.95. Clone Hacker's Bible - $34.95. Catalog - $3.00. COD'S (602) 782-2316. TELECODE, PO Box 6426-RE, Yuma, AZ 85366-6426. £ffi Parts 15" SUBWOOFER Internal lonal me. 2-1/2" SANYO TWEETER Paper cone with gold tone dusi cap. 8 oz, magnet 8 ohm. 1/2 - ferro fluid voice coil. Power handling: SOW RMS. 70W max. Frequency re- sponse: 3K-20KHZ. #RC-271-020 $1' 5 $1 7S 95c P0-59, ^rj0-jp| SUPER HORN TWEETER Original piezo tweeter made by Motorola. SPL=94dB2.83W1M Response: 4KHz- 27KHZ, Handles ap- proximately 50 waits. #RC-270-010 $5 M $4 M $3 ,s [E-9| 41Q-T91 ,e0,:p| Dual voice coil. 40 oz. magnet. 6 ohm imp. 100W RMS, 140W max. Response: 20-1.2KHi. Resonani frequency: 21 Hz. SPL«93dB 1W1M. #RC-290-190 $54 M n-3h S49» SUBWOOFER XOVER 2" DOME MIDRANGE Textile dome mid range made by Philips. 8 ohm. SPL=90dB1VW1M. 30W RMS, « W max. Response: SSQSKHz #RC-280-210 200W RMS crossover designed specifically for use with dual voice coil sub woofers 1 2 dB per octave roll-oft at 150 Hz. #RC-260-220 $28 M $24' 10" POLY WOOFER Medium duty. 60W RMS, BOW max. 14 oz. magnet. Response: 25-2.5KHz. fs«=28Hz. #RC-290-096 $18 M $16" TITANIUM COMPOSITE TWEETER , The advantages ol both hard and soft dome technologies. 8 ohm. Ferro fluid cooled voice coil. SPL=90dB 1W71M SOW RMS. 70W max. 4 H round- Pol ydax #DTW100T125. 12" CAST FRAME WOOFER / 12" woofer made in ihe USA by Eminence. Paper cone and dust cap with treated cloth sunound. 80 oz. magnet. 2-1/2" vented voice coil. Sohm. 170W RMS, 235W max. 40-4. 5KHz response. #RC-290-147 #RC-270-047 $27 M $24 M LI -HI ITQ-uph SPEAKER BUILDING bUUK Revised edition or David Weerns' be$1 selling book Learn to build low cost speakers that rival the high priced models. if #Rt>500-021 $ie« 340 E First St. , Da yim , Ohio i 5402 Locri:l-6l3-222-Q173 FAX: 513-222 4644 ■ 1 5 day money back guarantee - S 1 5.00 minimum order • We accept Masiereard, Visa. Discover, and C.O.D. orders. » 24 hour shipping. • Shipping change * UPS chart rale * $1 .0O(t3-,OO minimum charge) * Hours B.3-D am- 7:00 pm EST, Monday - Friday - Mail order custom- ers, please call lor shipping estimate on orders exceeding 5 lbs. Foreign customers please send $5-00 U.S. Fund's lor catalog postage. 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Bex 29237, Weitmount Postal Outlet 78 S Wonderland Road South London, Ontario, CANADA NoK 1M6 ZENITHS & TOCOMS SUPER Zenith (Z-TAC) converters (flashing)... $169.00. Zenith "turn-on" module... $49.00. Tocom 5503(A) & 5504 converters... $139,00. Toeoin (add-on J descrambters... $79.00. Tocom (5503-V1P & 55071 "turn-on" chips... $49. 00, CSN- EPLEX VIDEO GROUP. 1 (800) 726-4627. COMPUTER BOOKS DISCOUNT computer books! Thousands of titles available. Including recent releases. Please call or write (or our latest free catalog. BOOKWARE, 344 Watertown Road, Thomaslon, CT 06787. 1 [800] 288-5662. (203) 283-6973. CABLE TV DESCRAMBLER LIQUIDATION! FREE CATALOG! Hamlin Combos $44, Oak M35B $60 Imln. 5). ate. WEST COAST ELECTRONICS For Informatron: 818-709-1758 Catalogs & Orders; 800-628-9656 ALARM SYSTEMS ALARMING! Over 22 features are packed into Our security board! Protect your house, car. or boat. Just add switches, any speaker, and a battery! Special $59.95, including S&HI Check or M.O. 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No returns accepted. New Reduced Price PHOTOFLASH CAP. Rubicon CE 210 Mfd 330 Volt photo hash 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 terminals. CAT»PPC-210 $1 .25 each 10 tor $11. 00 ■ 100 for $100.00 Large quantities available. Call for pricing SWITCHES THUMBWHEEL SWITCH polo 10 position lecimal encoded .witches which iterlocktorTiake ap desired nurdber or digits. Terminates 1 1 pc pins (1 common and 10 poles], iach section measures .31" wide X ,20" ltgh X .78" deep. End plates can be add- Kt to form a ,94" high bezel. CAT#SWTH-S SI. 25 each 10forS10.00 2 END PLATES CAT*SW-S£C SI.OO'Soi MINIATURE TOGGLE Rated: 3 amps 120 Vac S.P.D.T. (ON-ON) PC, mount ;AT#MTS^PC $1.00 each 10 lor 19.00- ICOtor J80.0Q S.P.D.T. (ON-ON) solder luos ;AT#MTS-* SI. 35 each I0for$12.50- IOOIorJ.110.00 D.P.D.T. (ON-ON) solder lugs 3ATHMTS-S $1.75 each 10 tor J15.00 D.P.D.T, (ON-ON) P.C. mount ;AT#MTS-BPC $2.00eacti 10 for $17.50 1 m POWER SUPPLIES 5Vdc 3 AMP ACDC Electronics *5N3-1 Mew. prepped power supply with wires and connectors soldered to the Inputs and outputs. Open Irame style, Hegulat- ed. 4.94- X 4.03- X 2*. UL and CSA listed. CAT* PS -5 3 S 10.00 each 12 Vdc 5 AMP ACDC Electronics I 1 2N5 or equiv. Input: 1 00-240 Vac (wired for 1 15 Vac) Output: 1 2 Vdc @ 5 amps. Open frame style. T X 4 3/4 - X 3" high. Regulated. CAT* PS- 125 $37.50 each 24 Vdc 2.4 AMP Power-One Inc. IHC-24-2.4 Input: 1 15/;'30 Vac (wired (or 1 1 5 Vac) Output: 24 Vdc @ 2.4 arrp;.. Opne frame style. 5.62" X 4.87" X 2.50 - CSA listed. CAT* PS-2424 $30.00 each RECHARGEABLE BATTERIES 6 Volt t Amp/Hour Japan Storage Battery Co. Portalao PE6V1 w rf l $ Volt 1 Ah §EC2 rechargeable sealed lead -acid (gall cell). 2" X 1.635" X 2" high. Batteries are prepped with 5* black and red leads terminat- ed with 2 pin connector. CAT#GC-61 $4.75 each 1 for $42.50 Nlcke AAA SIZE $1.50 each 1 .2 volls 1 80 mAti CAT* HCB-AAA AASIZE $2.00 each 1 .25 volls 500 mAh CAT* MCB-AA AASIZE $2.20 each WITH SOLDER TABS CAT* NCB-SAA C SIZE $4.25 each 1.2 volts 1200 mAh CAT* NCB-C D SIZE $4.50 each 1.2 volts 1200 mAh CAT* KCB-D HEAVY DUTY "C" YUASA 1B00C Nickel-cad heavy duty "C" cell '•J t.2 volt. IBOOmah Price reduced on 10 or more. CAT* HO NCB-C 10 lor $42.50/100 for S375.0O INSTRUMENT ENCLOSURES High quality molded ABS Instrument enclosures. Integrated PC board stand oils and two sals of vertical mounting slots for front and rear sub panels. All enclosures are S" wide X 6 1/4" deep. Choice ol three his. Includes non-skid rubber leel and hardware. Available In beige. Ivory, black, and blue. Pin* ht CAT* ?I-V CiT»HB-A [7»uch tOkxKSOO 2SV CiUHB-B (7.75 ugh 10 tof (67.50 3- CAT* MM (SOOMOh 10 lot 170.00 Pk>a» specify color. RG-11/U VIDEO CABLE 100(1. or 200 It. rolls ol RG 1 1AJ 75 ohm cable terminated to heavy duty F connectors. Includes 75 ohm terminator and F-61 splicer on one end. New cables manu- factured for IBM PC networks. IBM P/H 1 501908 COM(SCOPE. CAT* RG -11-1 1001t. roB J15-00 CAT* HG-H-2 200 It, roll $27.50 L.E.D/S Standard JUMBO Did used T 1-3<4 size (5 mm) RED CAT* LED-t 10 tor $1.50 • 100tor$13.00 GREEN CAT* LED-: 10for»2.00- 100lor*l7.CO YELLOW CAT* LED-3 10 lor $2.00 ■ 100 lor $17.00 FLASHING LED W built in Hashing circuit 5 volt operation. T 1-3/4 (5mm) =rf»i RED $1.00 each CAT*LED-4 10 for $9.50 GREEN $1.00 each CAT*LED-.G10for$9.50 YELLOW $1.00 each CAT*LED-4Y10for$9.50 LED HOLDER Two piece holder. *■* ® CAT*HLED 10 lor 65* L.E.D. FLASHER KIT Two L.E.D.'b flash in unison when a 9 vott 3 battery Is attached. ~ This kji includes a ») ,. . i .Lt jus i iA OWE MINUTE TIMER OPTO SENSORS This evtiiio box with a b -tj button will drive you crazy. Box measures 3 1/4" square X T high, When the button Is pressed 4 LEDs light and a beeper pulses. Evan/ 1 5 Seconds one led goes out and the speed of the Deeping increases. At the end Of 60 sec- onds the unit gives ofl a long beep followed by a low squelch, all LEDs shut oft and the unil stops. Unit requires a S volt lran$Atoir baity ry (not incJucJed} to operate, CAT*TMR-1 $2.25 each * 10 tor $2000 Experirnentors Delight ATARI 5200 Vtdio Game Atari video game controllers returned to the dealer because ol various defects. None ol ihem work properly, but I hey nave lots of great parts. A RF video nrodulajor.wghi 16K dynamic RAM* in sockets, microprocessors and D-A converters in sockets, two voltage regulators on a heavy -duly heatsink and lots of 01 her ICs< capacrtors, ressstorsH connectors and of her conponent. Does nol inciude the power iransformer or controls (joysticks). CAT# A-5200 $7,50 each - 2 for $13.50 SOLD AS-IS For P#rt9 Onty. "WrQk Honeywell * HO A 0866- N 55 U-shaped opto sensor. 1/8' gap.4 pc ieads. CAT#OSU-S 75c each TAW#OPB-S18 U-shaped opto switch. 0.2 - gap between sensor and emitter. CAT* OSU-S 75* each TRW* OPB 822SD Reflective scanner module. U-shaped device with 4 leads each side (B total) 0.09" gap. 0.75" mounting centers. CAT#OSU-io 75* each TRW* OPS -708 Wedge-shaped reflective oplo ^i_ sensor. " CAT* OSF1 -b 75* each 7 p.c. board, all the parts and instructions to make a simple flash- er circuit. A quick and easy project lor anyone with basic soldering; skills. CATtLEDKIT $1.75 per kit LE.D. CHASER KIT Build this variable speed led chaser, 10 leds (fash sequentially at whatever speed you set them for. Easy to bukd kit includes pc board, pans and Instructions. Ideal for special lighting elects, costumes, etc. Oper- ates on 3 to 9 volts. PC board is 5" X 2.25". A great one hour project CAIN AEC 16.50 each STEPPING MOTOR CONTROLLER KIT Learn about stepping motors while building this simple circuit. Includes CircuH board. Stepping motor and all pans except 12 Vdc power supply, CATNSMKJT Sl8.00each METRONOME KIT This sirrpie device earn be set to dick from 20 to 1.000 beats per minute. Easy to build. Indudes circuit board, all components and instructions. Oper- ates on a 9 vort battery (nol included). OATH METRO 13.75 each PHOTO RESISTOR 1 ,000 ohms briohl light. 5^> 16K ohms dark. I ' 0.1 ar dta. X .Ortilgh, 0.1 8- long lead*. CAT* PRE-? 2 for $1.00 100 tor W5.00 - 1000 for wonoo ORDER TOLL FREE 1-800-826-5432 FAX (818) 781-2653 • INFORMATION (818) 904-0524 Call Or Write For Our Free 60 Page Catalog Outside the U.S.A. send $2.00 postage for a catalog. Minimum Order $10.00 'All Orders Can Be Charged To Visa, Mastercard Or Discover card • California, Add Sales Tax • Shipping And Handling $3.50 For the 48 Continental United States - AH Others including Alaska, Hawaii, PR. And Canada Must Pay Full Shipping • Quantities Limited • No C.O.D. • Prices Subject to change without notice. MAIL ORDERS TO: ALL ELECTRONICS CORP - P.O. BOX 567 - WW NUYS, CA 91408 CIRCLE 107 ON FREE INFORMATION CARD Tl m CD 33 C > 3D < 93 Freedom of Choice ^]*S2Sfe ,ioW e GoldStar 20MHz Oscilloscope Global Specialties Protoboard® Design Station Features: ■ 6" rectangular CRT display, internal gratitude & scale • Phase difference measurements between two forms under two methods x-y scope and Dual Trace - Two different scale probes: xt and x1Q • Bandwidth from DC to 20MHz • Includes: Two 40MHz probes, two fuses, power cord, operation manual, schematics and block and wiring diagram • High sensitivity: 1mV/div ■ Two-year manufacturer's warranty GS7020 $499,95 PB503 $299.9! Features: ■ Ideal for analog, digital and microprocessor circuits ■ Triple DC regulated power supplies, +5V, +15V. -15V • 8 logic probe circuits ■ Digital pulser ■ Function generator with sine, square, and triangle waveforms • Includes power supply, instrumentation and breadboarding Jameco Logic Pulser - Compare win TTL. DTL, RTL, HTL, HNIL MOS and CMOS ICs. - 1MSZ Syne input impedance ' Pu se: mode output current 10mA - Square wave current output: SmA - Audible tone LP540 $16.95 Jameco Logic Probe PROTOTYPING PRODUCTS Jameco Solderless Breadboards Mo. fir Comae! Binding Points Posls Price JE21 JE23 JE24 JE25 JE26 JE2T 3.251(2.125 6 5 > 2 '25 65.3 125 6.5 » 4 25 5.875x5.75 7.25 ■ 7.5 B3C 1.360 t.660 2,390 3.220 54.95 55.95 2 512,95 3 517.95 i 522.95 i 532.95 J AMECO 24 Hour Order Hotline (415)592-8097 ■ Max Frequency 80MHz ■ Minimum detectable Dulse: 10ns • I20KI1 input impedance ■ Max. supply voltage: :2SV ■ TTL threshold: (La).D.8V =0.tv (HI) .2.3v =0.2V ■ CMOS threshold: (Lo) 30% VCC MO% (Mt| 70%VCC --W% MS104 $24.95 Metex Digital Multimeters I General Specs; ■ Handheld, high accuracy * AC'DC voltage. AC/DC cufreni. resistance, diodes, cantinuily . transistor hF'E ■ Manual ranging w/ overload prelection M3550 & M4650cnly: • Afso measure frequency and capacitance M4650 only; * Datahotd switch - 4.5 digil M3610 3 S Oigrt MuUimeter $5995 M3650 3.5 Digit Mu*iimeter ^frequency & Capacitance $74.95 M465C 4 S Dsgn w/Requtticy. Capaaiance and Data HoW Swiich S99.95 A.R.T. EPROM Programmer * Programs all current EPROMs in the 271 6 to £7512 range plus the X2964 EEPROM ■RS232 port ■ Soflware included UVP EPROM Eraser r J ■ Erases all EPROM's ■ Erases 1 chip in 15 minutes and 8 chips in 21 min •UV intensity: 6800 LIW/CM 2 EPP $199.95 DE4 $79.95 EPROMs - for your programming needs P art No- Price FAX: (415) 592-2503 (41 5) 595-2664 Handheld Multimeter - 3.5 digit LCD with automatic polarity indication - AC/DC voltage measurement up to 500 volts ■ AC/DC current measurement up to 20CmA - Resistance measurement up tD 20MU - Con- tinuity checker with audible tone • Djode and logic tester ■ Auio'manual range and data hold tuncuons * All range protection and tunclion in. dications TMS2516 TMS2532 TMS2532-35 TMS2532A TMS2564 TMS2716 1702A 2708 2716 2716-1 27C16 2732 2732A-20 2732A-25 2732A-45 27C32 $4.95 6.95 7.49 7.95 5.95 5.95 4.89 6.95 3.49 3.95 4.25 4,95 3.95 3.75 3.49 3.95 Part No. Price Part No. Price 2764-20 2764-25 2764-45 2764A-20 2764A-25 27C64-15 27C64-25 271280TP 27128-20 27128-25 27128A-15 27128A-20 2712SA-25 27C128-15 27C1 28-25 272560TP $4.95 4.75 4.49 4.25 3.95 4.49 3.49 4.95 6.95 6.25 6.95 5.95 4.95 5.95 5.75 4.95 27256-15 27256-20 27256-25 27C256-15 27C256-20 27C256-25 2751 20TP 27512-20 27512-25 27C512-15 27C512-20 27C512-25 27C010-15 27C010-20 68764 68766-35 $5.9! 5.71 5.2! 6.9! 4.9! 4.4! 5.9! 7.9! 6,9! 8.9! 6.9! 6.4! 14.9! 13.9! 14.9! 12.9! Soldering and Desoldering Stations 60 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 B4Z°F ■ Sell contained high rotary vacuum pump DMM905 $49.95 XY999. .$299.95 94 Partial Listing • Over 4000 Electronic and Computer Components in Stock! CIRCLE 114 ON FREE INFORMATION CARD 24 Hours a Day. co«^!l **£#>_ oev* s Assemble Your own Computer Kit! Jameco 16MHz 80386SX Desktop Computer Kit ■ Building your own computer provides you with a better understanding of components and Iheir (unctions 1 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 16MHzB0386SX Desktop Computer Kit Includes: • 80386SX Motherboard with 2MB RAM (expandable to 8MB) • 101 -key enhanced keyboard • Multj I/O Card - Toshiba 1 .44MB, 3.5" DSHD floppy disk drive • Baby sized desktop case - 200 Watt power supply ■ DR DOS 5.0 by Digital Research and Diagsoft's QAPIus diagnostic software $11?|- 95 JE381 6 1 >'*'l Conner {16-bit IDE) CP3044 40MB 3.5' Low PraMe $469.95 CP3184 80MB 3.5'HH $899.95 CP31 04 ■0CMB 3.5'HH $799.95 ADP20 Host Adapter. $29.95 Relisys14"VGA Color Monitor J AMECO 24 Hour Order Hotline (415)592-8097 FAX: (415) 592-2503 (415)595-2664 1 355 Shoreway Road Belmont, CA 94002 Look to Jameco. WA ■ Max resolution: 720 x 480 ■ Bandwidth :30MHz •Input: DB1 5-pin (analog) RE9513 $449.95 Jameco 16-bit VGA Card ■ Supports VGA. EGA, CGA. MOA and Hercules modes « Comes wilh 256KB video RAM upgradable to 512KB (eight 414S4-S0) • Capable of B40 x 480 with £56 colors, 800 X 600 with 16 colors VG2000.. $149.95 Integrated Circuits Part No. 74LSO0 74LS02 74LS03 74LS04 74LS0S 74LS06 74LS07 74LS08 74LS10 74LS11 74LS13 74LS14 74LS20 74LS21 74LS27 74LS30 74LS32 74LB38 74LS42 74LS47 74LS48 74LS112 74LS1 22 74LS1 23 74 LSI 25 1-9 10+ $.25 $.15 .25 .15 .25 .15 .25 .15 .28 .18 .59 .49 .59 .49 .28 .18 .25 .15 .29 .19 .35 .25 .49 .39 .28 .19 .29 .19 .35 .25 .28 .18 .28 .18 .35 .25 .49 .39 .85 .75 .85 .75 .39 .29 .55 .45 .49 .39 .49 .39 Part No. _Li lfl± 74LS154 74LS155 74LS156 74LS1S7 74LS158 74LS166 74LS169 74LS173 74LS175 74LS181 74LS189 74LS190 74LS191 74LS193 74LS194 74LS221 74LS240 74LS241 74LS323 74LS541 74LS590 74LS670 74LS688 81 LS95 81 LS97 $1.29 .49 .49 .45 .39 .79 .99 .49 .39 1.39 3.95 .59 .59 .69 .69 .69 .59 .59 2.49 1.09 5.95 .89 2.19 .99 .99 $1.19 .39 .39 .35 .29 .69 .89 .39 .29 1.29 3.85 .49 .49 .59 .59 .59 .49 .49 2.25 .99 5.75 .79 1.95 .89 .89 Miscellaneous Components Potentiometers Values available (insert ohms into space marked "XX"): 500a 1K, 5K, 10K, 20K, 50K, 100K, 1MEG 43PXX 3 /4Walti5Turn $.99 63PXX 'ft Watt, 1 Turn.: $.89 transistors And Diodes PN2222 PN2907 $.12 12 10 25 1 N4735 2N3904.... $.25 12 2N4401 1N4148,,, 2M3055... 1N270..... $.15 07 1N4004 1N751 15 69 2N2222A.. C106B1 „ 49 25 Switches JMT123 SPDT. On-On (Toggle) $1.25 206-8 SPST, 1 6-pin (DIP) $1 .09 MPC121 SPDT,OnOtf-Ori(Tco3te) $1.19 M S1 02 SPST, Momentary (Push-Buttcn) $.39 D-Sub Connectors and Hoods D825P Male. 25-pin $.65 1 DB25H Hood $.39 DB25S Female, 25-pm... $.75 : LEDs XC209R Ti . (Red) $.141 XC556R Tl 3 /4. (Red) ... $.12 XC556G T 1 3 a (Green) ,. . 1 6 XC556 Y T1 3 /i, (Ye llow). ..16 IC Sockets Wire Wrap (Gold) Level #2 8WW $.49 14WW 65 16WW 69 24WW 1.05 28WW 1.29 40WW 1.79 Low Profile 8LP $.11 14LP 12 16LP 13 24LP 19 28LP 22 40LP 28 Solderlail Standard & Header Plug Sockets Also Available • Wide selection of integrated circuits and components • Quality prototype and test equipment • Computer kits and accessories Additional items thai 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 Of write for trie latest Jameco catalog! $50.00 Minimum Order Data Sheets - 50c each For a FHEE 9Q.Page catalog send 52.00 10 cover first Class Postage and Handling ® 1991 Jameco Electronics 3/91 CA Residents Add 5.25%, 6.75% or 7.25% Sales Tax Shipping - Add 5% plus $1 .50 Insurance (May vary according lo weight anrE snipping method! Terms: Prices subject to change without notice. Items subject to availability and prior sate. Gomplele list of lera»i*«arranlle5 is available upwi taqja^K IGM 13 a ragiMarod Iradrunark oi fcilsmswiull &usinfl« Mnetwiw MMC ■ecr- <£5~v> Please refer to Mail Key 2 when ordering • Customer Service -Technical Assistance • Credit Department • All Other Inquiries • (415) 592-8097 • 7AM -4PM P.S.T. CIRCLE 114 ON FREE INFORMATION CARD m 03 33 C > -< 95 LASERS AND SCIENTIFIC DEVICES VRLSK 3mw Vis Red Laser Diode Syslem Kit $159.50 LLIS1K Laser Beam "Bounce' Listener Hit ,..,....$189.60 LHCJK Visible Simulated 3 Color Laser Kit $44.50 LC7 40 Watl Suming Culling Laser Plans S2O-Q0 I'Uii-i HI Powered Pulsed Drilling Laser Plans $20 co LGU40 1 In 2mw HeNe Vis Red Laser Gun Assembled 5199.00 LLS1 Laser Lit! Show - 3 Methods Plans $20.(10 SD5X Sal in Ihe Dart Kit $299.50 EML1K Electromagnetic Coil Gun Kit $69.50 MO-! Hi Velocity Coil Gun Plans $15.00 LEVI Levitating Device Plans , $10.00 EH1 Electronic Hypnotism Techniques Plans $10.00 HIGH VOLTAGE AND PLASMA DISPLAY DEVICES IIVM7K 75.000 Volt DC Variable Onlp'.il Lab Source Kit $149.50 IDG3K lonflayEjunKll.proJectenergywItrioulwlres $69.50 NIG9K 12V.-1 15 VAC Hi Qui Neg Inn Generator Kit $34.50 EMA1K TeleKineltc Enhancer/Electric Man Assembled... $99.50 LGSK Lightning Display Glohe Kit $54.50 BTC1K Worlds Smallest Tesla Coil Kit $49.50 BTC3K 250KV Table Too Tesla Coil Kit $249.50 BTC5 1.5 Million Veils Tesla Coil Plans $20.00 JL3 Jacobs Ladder - 3 Models Plans ..$15 00 GF.A1 Arali Gravity Generator Plans 510,00 PFS20 Plasma Fire Saber Assembled $69.50 □ PL2Q Dancing Plasma tn Music and Sounds Assembled $79.50 SECURITY AND PROTECTION DEVICES I i r.1 ; ii 100,000 Voll Inlimidalor up to 29' Assembled SI29.50 IPG7D Invisible Pain Field Blast Wave Gen Assembled $74.50 PSP4K Phaser Sonic Blast Wave Pistol Kit $59.50 list i) tnlinity Xrnii Listen in Via Phone Assembled S199.50 TAT30 Automatic Tel Recording Device Assembled $24.50 VWM7K3Wi, FM Aulo Tel Transmitter KI1 $49.50 FMV1K 3 Ml. FM Voice Transmitter Kit $39.50 HOC1K Homino/Ttacking Beeper Transmitter Kit $49.50 EASY ORDERING PROCEDURE Ttjll FREE 1-300 -221-1705 i' 24 II 4 ON I S03-S73 ■■. .■'.■(■ or FAX IT TO 1 603 -672-5416 VISA. MC. CHECK. WD IN US FUNDS. INCLUDE 10% SHIPPING. ORDERS 5100.00 S UP DNLV ADO StO.OO. CATALOG $1.00 OR FREE WITH ORDER. INFORMATION UNLIMITED P.O. BOX 716, DEPT. R3, AMHERST, NH 03031 THE ELECTRONIC GOLPMINE co o •z o tx i LJJ -J LJJ 6 < fX 96 •—^ I— J " TIib Elcdrenle Csldmlci has we rj the greatest se-J lections ol uninje etectuonc ' kits av^ulabte in ate vAdtf ' We hove over 130 b'tsandner1.4rx] unique, bargain priced, ccmtnnenls our catalog! OVER MIS T ,FFETtEt)T I copttooms MINI GEIGER COUNTER KIT Ce^Xs ALL Tftra of F^dcaJion Uses Sensitive ALpta Window Tuts Cperals from SN M&f {ixA Incl,) Comes with PC Boari. Pans, lube and Instructions SiaedPCBowt 3" x l.gr C6430 $59.95 4KU TRIGGER COIL Use hriba^tfolK ! lute trial needs a N170Q- $1.25 EA 100 kx SBO.OO "^ INVERTER c ^ TRANSFORMER J^ Small 4 letf uanSiatw tor is «iih 565 C to corral 12VDC Id 2XV lor strata ftuoHcsni lutes with sd*rax N1703 $2.00 EA 1,000 iw Sl h 5W CDS CELL ASSORT*JE G/eai roi lujndndsoi prajbcls art experiments, Tftest tiiangB ihefcr resistance *juf litft 5 different types \\ G7G4 5 for $2.00 GIAKT HORSESHOE XENON STROBE TUBE, Urges HarasfiOE Tuts vwi hM ever seen! Make a behemciuin strDbe Id Irigrten evcyone on Hal- Kwen, or use il ir a wrcfoi- cf a disco flirte! Size: 2' ls> x 1-ljfltr vide, glass Eubing dia. ytf Operal/a hi 30DVDC and can te used wlft our 4KV trigger Irais- J :-™ (iiKt/ ttiTOO to lelfr G762 $7,00 each RARE EARTH MAI Many sima stronger nan rthef L^r.: 5 . meje arc in; ^" g the wrttfs strar^tsl cdntnacedly Mil- sbie rnagrneti for wis sis. Small sta Nity aboil 1.63 ■ tJSFX if yet on iffl up la 10 kg. Try to renvtrt Irus irarjttt Iron a sal p-as. ara yDuillindiraun^sifwsiialjoucanTBBliiDll! Grea it: LtwiEaids o- eq^rinients and a^piica- bens. Horre >■ trcse sell lev o«i £60 each, tut inese are smplus aid love a lew cKp^does net cded periormaiia). G7&5 59.00 M1NII,1UM OHDER: $1000 ptus 53 00 shipping and tiandlmg Wa aKefJt MC, Visa and Money Ortiers- SEND ORDERS TO: The Electronic Goldmine P.O. Box 5408 Sconsogfe, KL 8S261 PHOUB ORDERS: (602] 451-7454 CIRCLE 1BB 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 HIS AMC Sales H2 75 Ace Products 42 107 All Electronics 93 180 Alpha Products 17 — Amazing Concepts % 77 B&K Precision 19 67 Banner Technical Books 80 98 Beckman 75 109 C&S Sales 36 70 CEI 91 — CIE 5,25 50 Caig Laboratories 29 179 Chenesko Products 42 — Command Productions 30 187 Communications Specialists 86 183 CompuServe CV4 55 Contact East 42 58 Cook's Institute 18 184 D&D Electronics 3 127 Deco Industries 42 188 Electronic Goldmine 96 — Electronics Book Club 1 1 ,32 121 Fluke Manufacturing CV2 185 General Technics 42 186 Global Specialties 27,26 — Grantham College 54 86 Heathkit 16 — ISCET 9 1 14 Jameco 93,94 104 Jan Crystals 18 — King Wholesale 88 53 MD Electronics 90 93 Mark V. Electronics 91 61 Microprocessors Unlld 79 — NRI Schools 15.85 181 Optoelectronics CV3 56 Parts Express 89 193 People's College 21 182 Print Products International 29 78 Radio Shack 7 177 SCO Electronics 76 — Star Circuits 30 194 Unicorn 92 178 U.S. Cable 76 189 Viejo Publications 82 190 WPT Publications 86 191 Xandi Electronics 42 ADVERTISING SALES OFFICE Gernsback Publications, Inc. 500-B Bi County Blvd. Farmingdale, NY 11735 1(516) 293-3000 President: Larry Stickler Vice President: Cathy Steckler For Advertising ONLY 516293-3000 Fax 1-516-293-3115 Larry Steckler publisher Arline Fishman advertising director Dentse Haven advertising assistant Christina Estrada advertising associate Kelly McQuade credit manager Subscriber Customer Service 1-800-2B8-0652 Order Entry for New Subscribers 1-800-999-7139 7:00 AM - 6:00 PM M-F MST SALES OFFICES EAST/SOUTHEAST Stanley Levitan, Eastern Sales Manager Radio- Electronics 2E9-23 57 th Avenue Little Neck, NY 11362 1 -71 8-428-6037, 1-516-293-3000 Fax 1-718-225-8594 MIDWEST/Texas/Arkansas/Okla, Ralph Bergen, Midwest Sales Manager Radio-Electronics 540 Frontage Road— Suite 339 Northfield, IL 50093 t -708 -446- 1444 Fax 1-708-446-8451 PACIFIC COAST/ Mountain States Marvin Green, Pacific Sales Manager Radio-Electronics 5430 Van Nuys Blvd. Suite 316 VanNuys, CA91401 1-B1 8-986-2001 Fax 1-818-986-2003 *jjqii; fwWBiM H 1 1 Vl'fj 3000 ^Top of the Line Universal Handi-Counter™ . rri^. $375. 2600 Super Sensitive RF Frequency Finder. $325. 2210A Full Range Pocket Size LED. $239. T 8030 Bench Portable (Fits in an attache case) with ALL the Handi-Counter™ Features plus More. $579. Model Range Low High Display B Digit LSD Display JO Digit LCD Signal Strength 6 a [graph Universal Counter TCXO Option 9030 10Hz 2.4GHI • • • i lppm add SI 25. 30O0 10HI 2.4GHz • • ■ i .2ppm add S 80. 260Q 1MHz 2.4GHz • • • ± 2ppm add $ 80. 221 DA 10HZ 2.4GHz • + 5ppm odd S 75. 13QDH/A 1MHz 1 3GHz • ± .5ppm add S 75 Sensitivity: <1 ro <10mV typical NICads & AC Charger/ Adapter included. Carry Case. Antennas ana Probes extra One year parts & labor warranty on all products OFF THEBENCH AND RUNNING When OPTOELECTRONICS took fre- quency counters off the bench we created a whole new dimension - Frequency Finding . Our HandhCounters™ make Frequency Finding a reality by allowing you to pick-up radio transmitters at the maximum possible distance. Monitoring Enthusiast, Security Specialists, Broadcast and Design Engineers, Two Way and Amateur Radio Operators and Service Techni- cians have all made the move. Shouldn't you? 1300H/A Low Cost Ultra Sensitive (HF, UHF,VHF). $179. ™™lectiiqnic Toll Free Order Line: 1-800-327-5912 In Florida call (305)771-2050 FAX (305)771-2052 5821 N£ 14th Avenue • Ft, Lauderdale, FL 33334 Visa, MC, COD, Cash, M.O. accepted. Personal Check allow 3 weeks. 5% Shipping. Handling, (Maximum 310) U.S. & Canada. 15% outside continental U.S.A. CIRCLE 181 ON FREE INFORMATION CARD fjh- TThere| nothing newabout having everything ^ ""5 you need inoneplace. "~ WithCornpuServe, it's all at your fingertips. When you become a member of CompuServe, you join a vital, active community of over 500,000 friends and neighbors from all over the world. Small-town friendly We keep in touch with electronic mail and faxes, and by posting messages on our bulletin boards. 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