(J; 48783 JULY 1991 Radio ■ ^^ aaaBW JULT 1991 EEtronics TECHNOLOGY - VIDEO - STEREO BUILD YOUR OWN EKG Keep tabs on your heart with R-E's electrocardiograph! BUILD A COLOR-BAR TEST GENERATOR Test and troubleshoot your video equipment. D/A and A/D CONVERTE A look at the chips that bring the digital and analog worlds together: BUILD A LOGIC ANALYZER A 16-channel, 50-MHz digital troubleshooting tool TEST IC's WITH YOUR P And learn about computer- based test equipment. $2.95 U.S. $3.75 CAN I GERHSBACK 11. ;-,| :■•■■ < IN am ^^.aa aw ,a ■•««• a ■ ■• ■ ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■ «aanaauaan-_- ■•■■■• ■ 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 ZQ, to 160 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- onal Display True-rms vollage and cur- rent, including ac+dc 0.02% basic dc voltage dB, W'i'i 21 reference impedances, and audio pgwer calculations Compare and Relative functions Min Max and Touch Hold* functions accuracy 0.05% basic dc current Optional PC sottware for RS-232 applications accuracy Optional IEEE-488.2 interface, t MHz frequency counter battery pack RS-232 interface standard One year warranty •SiijjislKtU.S.UslPrla John Fluke Mfg. Co., Inc. P.O. Box 9090 M/S 250C Everett WA 98206 U.S.: 206 -356 -540(1 Canada: 41B-B9O-760O Other Countries: 206-356-5500 © Copyright 1989. 1990 Jotiri Fluke Mfg. Co.. Inc. All rights reserved. Ad no. 00015. IBM PC is a registered trademark of International Business Machines Corporation. FROM THE WORLD LEADER IN DIGITAL MULTIMETERS CIRCLE 121 ON FREE INFORMATION CARD July 1991 MZlBEtrtJMJiES 31 BUILD AN ELECTROCARDIOGRAPH Learn about medical electronics while monitoring your heart. H. Edwards Roberts, M.D. 41 COLOR BAR GENERATOR Test and troubleshoot your video equipment. Thomas Gould 47 LOGIC ANALYZER Check digital circuits with our 16-chanrtel, 50-MHz logic analyzer. Gerard Robidoux and Robert Dmitroea 53 EXPERIMENTING WITH PC-BASED TEST EQUIPMENT Build a PC-based IC tester for less than $1 00! James J. Barbarello 58 DIGITAL-TO-ANALOG AND ANALOG-TO-DIGITAL CONVERTERS An in-depth look at the chips that bridge the digital and analog worlds. Stephen J. Bigelow ■'NJ:i:^N^ 6 VIDEO NEWS What's new in this fast- changing field. David Lachenbruch 20 EQUIPMENT REPORTS Fluke Model 79 DMM. 65 HARDWARE HACKER Understanding transformers, and more. Don Lancaster 72 AUDIO UPDATE A distortion primer: Part 2. Larry Klein 80 COMPUTER CONNECTIONS A new beginning for this column. Jeff Holtzman Vol. 62 No. 7 PAGE 47 ffSflfr PAGE 41 94 Advertising and Sales Offices 94 Advertising Index 8 Ask RE 10 Letters 84 Market Center 29 New Lit 22 New Products 4 What's News c 5 g z o (X H CJ> LU Q < If you've been having heart pal- pitations, see a doctor. But if you've simply been curious about medical electronics and like to keep tabs on includes t. CLEVELAND INSTITUTE OF ELECTRONICS, INC. 1 77S Easn 7W strew * Cleveland. Ohio 4* 1 M * (2 16) 78 ? -9400 *««i B«* 'J Since 1934- AE17 il.H.lM^Vi-- What's new in the fast-changing video industry. DAVID LACHENBRUCH • Multimedia hits the market. The first interactive multimedia sys- tem for consumers is now on the mar- ket. Starting in California in April, and now gradually scheduled to spread out across the rest of the United States, Europe, and Japan, is CDTV (which stands for Commodore Dy- namic Total Video), a CD-ROM- based system derived from Com- modores versatile Amiga computer. Although CDTV doesn't yet provide full motion, it came to market at a $999 suggested list price with a li- brary of some 50 titles available, mainly between $30 and $80. CDTV plugs into the RF, video, or S-video input of the TV set, and a wireless remote control manipulates an on- screen cursor for viewer input. Among the available programs are an atlas, an encyclopedia, and a diction- ary, plus games, children's stories, interactive mysteries, and "coloring books." Later this year, CDTV is expected to have company in the form of Com- pact Disc-Interactive, or CD-I, de- veloped largely by Philips but endorsed by Panasonic, Sony, and other Japanese manufacturers. Nei- ther CD-I nor CDTV has full motion on-screen, and the two systems are mutually incompatible. However, Phi- lips said that it will make available simple, plug-in full-motion adapters after standards are finalized, or sometime in 1992, and Commodore said that it will adopt full-motion video as well. Whether interactive multi- media is the next major consumer- electronics trend or if it turns out to be just another gadget looking for a use is still up to the market to deter- mine. • Compressed cable. Digital compression is the hot topic in the cable TV business these days, with a number of systems due to be tested on the consumer market soon. Cable TV Laboratories, supported by cable operators, has formed a digital-com- pression consortium with General In- strument and Scientific-Atlanta to speed the introduction of com- pressed-signal systems. These sys- tems will use compression to squeeze a number of programs onto a single channel, first for satellite de- livery and later for delivery to private homes. Meanwhile, a "non-compressed" 150-channel system is now being in- stalled in Queens, NY, by Time Warn- er in the upgrading of a 75-channel system. The system will use fiber op- tics as a trunk carrier, and newly de- veloped equipment to feed the 150 channels into standard coaxial cables that are already going into the area. Time Warner officials said the system will make it possible eventually to beam special programs to specific neighborhoods and even to individual homes. With the use of digital compres- sion, the same system will be able to carry 600 to 1200 channels, accord- ing to Time Warner. With such a sys- tem on the way, according to cable industry officials, the problem is no longer a technical one but a market- ing issue — determining what kind of programs should be carried on the wealth of channels that will become available. • Still plus motion. Although sev- eral manufacturers have introduced digital electronic snapshot cameras, they haven't gained widespread pop- ularity, presumably because of high price and somewhat limited utility. Perhaps the answer to the problem is, as Hitachi believes, to combine the electronic still camera with the cam- corder. As demonstrated at a recent technology exhibition in Tokyo, the Hitachi camera can make a standard analog 8mm videotape. However, it also has a "snapshot" button, which, when pressed, can record a still, high- definition, digital picture on the 8mm tape's audio track. The still snapshot may be made at the same time a videotape is being shot, at the rate of one snapshot every 12 seconds. In the prototype, six one-megabit DRAM's are used for digital still re- cording. While the conventional Hi8 analog tape recording has a band- width of 500 kHz, the still picture re- cording made with the same camera has a bandwidth of 2 MHz. The still picture has resolution of 768 lines vertically and 512 horizontally, Hitachi says. The prototype camcorder used two 410.000-pixel CCD's. Hitachi says the digital still feature will add about $150 to $220 to the cost of a Hi8 camcorder, but it will eliminate the need for a separate still camera. A simpler still-motion camcorder system is already on the market in Europe, where a Philips Super VHS camcorder is designed to make a full- frame analog still recording or a stan- dard S-VHS moving tape at the op- tion of the operator. You'll have to choose one format at a time: the two can't be made at the same time. • Old names for new. Hey, you TV-nostalgia buffs — Admiral is back, and so is Crosley. but Majestic died again, The famous-name revival con- tinues in TV brands. Although the Majestic brand was revived for a short time, that old devil recession did it in; products with that brand name have been suspended. How- ever, Montgomery Ward paid some money to an appliance manufacturer and revived the brand name of Admi- ral, a pioneer once known for its cheap TV sets. "Monkey Ward" also plans to field a line of TV's under the Bell & Howell label — a name that sounds like it once was a high-end TV but never really was (it was applied to slide and movie projectors and audio tape recorders). Another old-timer, Crosley, is doing quite well as a pri- vate brand for smaller dealers. And, of course, there's Emerson, which in the last 10 years has made an im- pressive comeback, although it's not related to the original Emerson Ra- dio, which pioneered table model ra- dios and smaller TV's. In fact, none of these brands are related to their origi- nal ancestor. But then. RCA and GE, as well as Magnavox, Sylvania, and Philco, are now made by new owners, although they do happen to have some direct lineage from TV's pi- oneering days. R-E SELECT 5 BOOKS for only $ 4 a5 (values to $102.75) 9M0 SJCQC 0,UN |S H 2 METERS 1 " SCOPES "-fill* ml>Kiun*i4 3321 P 516.95 3632 $18.95 Your most complete source for electronics books for over 25 years. simp ii6.es 3279 S36.95 Counts SS 2 31A7P 513.95 2M5F Si 1.65 3130 560.00 Counts « 3 3M1P J1 7.95 Srtms X Milirs SSSOP 919,35 < 111 lime i ii m s: '.r •■ 3267P 515.95 8 3343 S25.9S Counts as 2 Membership Benefits * Big Savings. In addition to this introductory offer, you keep saving substantially with members' prices of up to 50% off the publishers' prices. * Bonus Books. Starting immediately, you will be eligible for our Bonus Book Plan, with savings of up to 80% off publishers' prices, * Club News Bulletins. 15 times per year you will receive the Book Club News, describ- ing all the current selections — mains, alternates, extras — plus bonus offers and special sales, with scores of titles to choose from. * Automatic Order. If you want the Main Selection, do nothing and it will be sent to you automatically. If you prefer another selection, or no book at all, simply indicate your choice on the reply form provided. You will have at least 10 days to decide. As a member, you agree to purchase at least 3 books within the next 12 months and may resign at any time thereafter. • Ironclad No- Risk Guarantee. If not satisfied with your books, return them within 10 days without obligation! • Exceptional Quality. All books are qual- ity publishers' editions especially selected by our Editorial Board. 3329 529.95 !1671 > $ 1a 5; Counts u 2 2937P £16.95 2925P 39.95 337JP (16.55 27Q7P 917.95 1 ■«. Basic Electronics Course _r.r^- 2B0OP St6.95 261 3 P Sir. 95 All books are hardcover unless number is followed by a "P" for paperback. ELECTAQNCSBaDKCLUB Blue Ridge Summit, PA 17294-0810 Please accept my membership in the Electronics Bock Ciub and send the 5 volumes listed below, billing me $4,95. If not satisfied, I may return the books within len days without obliga- tion and have my membership cancelled- 1 agree to purchase at least 3 books at regular Club prices during the next 12 months and may resign any time thereafter, A shipping/handling charge and sales tax will be added to all orders. Name . Address City _ State _ Zip Phone Valid 1or new members only. Foreign applicants will recewt- apacial wrJoring instructions. Canada must remit ■n U.S. currency. Thii ordsr subje-cl lo acceptance by the E.&clronjcs Bock Ciub. RPIE791 2995 525.65 3*45 S 2 1.35 Cciii-! 3 ftt Z Troubleshooting ft Repairing ± VCRs I 3777 S32.9S Counts as 2 n 1G07« 539.95 Counts H 2 32?S 122*5 3370 S32.9S Cauinti H 2 292G S25.95 Counts u 2 BtuDYmkcnw 7FP 3343 S29-9S Ceun! j at 2 3475 S27.9S Counts as 2 (Publishers' Prices Shown} ©1991 ELECTRONICS BOOK CLUB AUDIOPHILE ATTITUDES My thanks to Radio-Elec- tronics, and especially to Larry Klein, for his excellent series of arti- cles about audiophile attitudes and equipment. His well-reasoned and fully documented data are long over- due. The level of foolishness in the con- sumer-audio and audiophile markets should be an embarrassment to all professionals in the electronics field. Beliefs in things ranging from absurd speaker cables to "greening" of CD's are no more legitimate than Creation Science, and the audio faithful who are willing to part with $10,000 or more for an antiquated tube amplifier must surely qualify as the all-time champions of gullibility. Thanks again. PAUL J. CARLSON Pittsburgh, PA MAGNETIC FIELD METER QUERIES I really enjoyed Reinhard Metz's ar- ticle, "Build this Magnetic Field Meter' 1 (Radio-Electronics, April 1991). I thought the issues of possible health risks, magnetic field theory, and the pictures of sources of mag- netic-field exposure were presented very well. For the last year I have been in- volved in evaluating problems con- cerning ELF magnetic fields and remedial solutions. Part of my work was directed to evaluating Gauss meters and magnetic-field measure- ment systems. t have three questions about the meter. First, I wonder if the un- shielded coil on the PC board might be sensitive to the electric as well as the magnetic fields, and because of the differing vectors, give ambiguous readings? Second, the article stated that the meter is usable in a frequen- cy range from 50 Hz to 20 kHz. Is the meter reasonably flat with frequency over its entire dynamic range? I know that this can be a serious problem and can lead to substantial errors in measurement. Third, I worry that the relative insensitivity (0.1 |xF) of this meter, along with its high (20 mT) range, might cause people to expose themselves to those 10—20 mT fields while making measurements. Per- haps a note cautioning against that would have been wise. If the meter range had been 0.001-20 fiT, over- ranging would tend to prevent possi- bly hazardous exposure. I hope I'm not being overcritical of the meter. Again, I'd like to thank Mr. Metz and Radio-Electronics for presenting this important information to the public, JOHN MILLS Ben Lomond, CA Thank you for your kind comments about my article. In response to your questions: First, while the magnetic field pickup coil might be considered an antenna for the electric fields, its small size would make it efficient as such only at relatively high frequen- cies, where the op-amps are ineffec- tive. At lower frequencies, the electric field pickup appears primarily as common-mode voltage, and should not get amplified. Tests of the unit have been successfully con- ducted in RF fields up to 20 volts/ meter. Second, in regard to frequency range and flatness of response, while it was stated that the response was from 50 Hz to 20 kHz, it was in fact optimized for power-line frequencies and their third harmonics. If your are interested in optimal flatness to 20 kHz, I would suggest changing the following component values: R3 be- comes 16K and R12 becomes 80 ohms (or C7 becomes 800 pFX Finally, I'm not sure how the 20-mT range of the meter would "cause" a person to expose themselves to CORRECTIONS There was a slight error in the cir- cuit that was sent in to us from Johnny Bruyns of Port Shepstone, South Af- rica (Letters, January 1991), There should be a 4.7K resistor between the + V supply line and pin 7 of IC2. The direct connection that was shown should be replaced by the 4.7K resistor. fields in that range, unless they delib- erately set out to create them for the sake of a meter deflection. That cer- tainly would not be advised. However, to the extent that they may exist in some places and are detected by the meter, I agree that people should use that information to avoid further po- tentially hazardous exposure. REINHARD METZ ELECTRONICS BEHIND BARS I'd like to thank Radio-Elec- tronics for keeping alive my interest in electronics for the last eleven years. Without your magazine, I would not have been able to keep abreast of the massive changes in the industry. You see, I am a prisoner serving 15 years for committing a crime of passion. Since I entered pris- on in 1980, I have relied on your mag- azine to keep me informed of the changes. Had I not received a monthly issue, I would find myself upon release to be totally out of touch. All this time, without so much as seeing a soldering iron, your maga- zine has helped me to keep the faith. In two years, I will be returning to a new life. Before leaving here. I hope to impart an enthusiasm for elec- tronics to other prisoners. For five years, I have struggled to establish an electronics hobby club. Last week I was given permission. Most of the people I met in prison have not had the advantages I've had in my life. I know in my heart that fostering an interest in electronics and giving some of the other prisoners the basics of electronics will lead to a confidence in their abilities that will aid in reformation. I'm asking for help from any of your readers who might have old copies of Radio-Electronics. Popular Electronics, Hands-on Elec- tronics, or other electronic publica- tions to send them to me. We'd also appreciate any plans or projects that they'd like to share, as well as old books, specification sheets, or help- ful hints. Perhaps the most important thing I hope your readers can send is support — support in the form of let- ters to club members. If anyone can write a letter a month to answer some basic electronics questions from pris- oners, please contact me. Thank you. ED MOORE c/o Chapel Kingston Penitentiary Kingston. Ontario Canada, K7L 4V7 IN FAVOR OF AMIGA Congratulations. Mr. Holtzman, You really had me going there, with your reply to Mr. Cheng in the April issue of Radio-Electronics. "Why doesn't Commodore build a low-cost MS-DOS multimedia machine." Don't be ridiculous! Perhaps if I'd re- ceived my issue on April 1 , instead of in mid-March, I would have caught on sooner. Unfortunately, I believe that some of Mr. Holtzman s other statements and observations are sincere. He claims that the Amiga has had little influence on the personal-computer industry. How does he define "influ- ence?" By counting sheer numbers, or by cloning to the point of becoming a commodity? I hope not; that is a very uninteresting way of looking at things. If he hasn't already noticed, personal computers (PC's and Macs alike) are becoming more "Amiga- like" (multitasking, GUI's, coprocessors, a multitude of colors, etc.). That sure looks like influence to me! Perhaps his view of the personal computer industry is just narrow and biased. I admit, the Amiga has broken no ground in the big three of applica- tions: word processing, spreadsheets, and databases. How- ever, if you consider the growing mar- ket for personal-computer graphics. the Amiga is a technological leader. I can't begin to list all the paint pro- grams, 3-D modelling, rendering, and animation applications that exist for the Amiga. The simple fact is that what is considered "state of the art" in MS-DOS graphics software is rather crude by Amiga standards. I believe that Mr, Holtzman is "not anti-Amiga," Unfortunately, he is far worse — he is indifferent. Radio- Electronics and the majority of other "general interest" magazines continue to ignore the Amiga and help perpetuate the myth that it is not a "serious computer." Finally, I do have to agree with Mr. Holtzman concerning things like data interchange standards. We in the Amiga community are blessed with the IFF data standards; I wish it was just as easy to work across other platforms, I, like millions of others, prefer being on the leading edge of person- al-computer technology. In your zeal for standards, please don't expect everyone to descend to the level of IBM/ MS-DOS. There is more than one way to process bits! TOM HUTCHINSON Pilot Rock, OR APRIL SPIRIT I loved your "Poor Man's Laser Printer" article (Radio-Elec- tronics. April 1991). Let me tell you, the idea was great! I have attached a Panasonic 1991 Multisynch color monitor to a Pan- asonic FP-C1XE Digital Color Copier using your method. The results in Super VGA were, to say the least. incredible! Two things are troubling me though. One is the dither moire I am getting, and the other is the cost: $20,000 is a lot for color printing. JESS KIDDING Tonguen Cheek, NJ Be an FCC LICENSED ELECTRONIC TECHNICIAN! 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Visit your local distributor today and you'll agree the choice is obvious Fluke Model 77 Beckman Industrial HMS2Z5 3-V2 Digits 4 Dipt 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 IDA Range (Fused 1DA Range ifuku Protective Holster Protective Holster 3 Yr. Warranty 3 Yr. Warranty - True RMS - Auto Mln Man™ - Relative Mode S165- $149 s Touch Hold is a registered trademark ot the John Fluke Mtg, Co., Inc. •199 1 Flu ke and Philips U.S. Price List. J N 1 90-0 1 -07 9 1 Beckman Industrial' An Atfmate of Bmerson Efecwc Co Instrumentation Products Division 38S3 Ruffin Road. San Diego. CA 9ZW3-i898 (619) 49^3200 ■ FAX (619) 2J&0172 ■ TLX 249031 Outside California I-S0O-SS4-27GS Wimin California 1-S0O-227-9781 © 1990 rkekmsin industrial Corporation. Spedflcatlnni subject 10 change wsth«ui notice. Hubs. 1 is a irpshjrei) irjsk'mark of john Fluk Mfe Cn. Inc CIRCLE 98 ON FREE INFORMATION CARD C 5 to Your Ticket To SUCCESS Over 28,000 technicians have gained admit- tance worldwide as certified professionals. Let your ticket start opening doors for you. ISCET offers Journeyman certification in Consumer Electronics, Industrial, Medical, Communications, Radar, Computer and Video. For more information, contact the International Society of Certified Electro- nics Technicians, 2708 West Berry Street. Fort Worth, TX 76109; (817) 921-9101. Name Address_ City State _Zip_ _Send material about ISCET and becoming certified. _Send one "Study Guide for the Associate Level CETTest." En- closed is $10 (inc. postagel. FCC NO-CODE AMATEUR RADIO LICENSE The FCC recently passed Docket 90- 55 which for the first time allows a new codeless entry ham radio license of technician grade. Privileges 30 MHz and above — All modes! (See R.E. ar- ticle in April 1991 issue). Get all the no-code license details, study & testing information plus a one- year subscription to one of ham radio's longest running specialty mode publi- cations that will teach you all about the new modes you will be able to operate! FSTV SSTV FAX RTTY PACKET AMTOR OSCAR FM REPEATERS MICROWAVE AND LOTS MORE! w a II o % UJ g < n 10 SEND $25 CHECK OR MONEY ORDER f~. / OUR Z4TH YEAR SINCE 1967! ►5i ■2^^ The SPEC-COM Journal P.O. Box 1002, Dubuque, IA 52004 (319)557-8791 MCAflSA (5% added) COMPUTER CLASHES CONTINUED I really do think that Mr. Cheng's comments in the April "Letters" col- umn went a bit far — and so did Mr. Holtzman's reply. The entire ex- change brings to mind the old tale about the blind man and the elephant; it really is tough to discern the big picture through all the fog. As one who has programmed extensively for 80X86 PCs, Amigas, and other com- puters, I have more comments than I can fit in a reasonably sized letter. A few will have to do. First, on standardization: As Mr. Holtzman pointed out, the desirable part about standardization is that it facilitates communication. There are two flip sides. One is that many soft- ware (as well as hardware) suppliers don't want communication. Suppliers of programs for CAD and music scor- ing are especially notorious — they want you locked in tight. The second is that standards are often ages out of date — witness the KlTSC televi- sion standard — to the point of stifling innovation. The niche machines are a paradox. They owe their existence to the fact that in one important sense they are more standardized than PC's. No two PC's are alike, even in such funda- mentals as memory organization, vid- eo graphics layout, and interrupt organization. As we all know, that causes no end of problems. Within the CPU itself, the instruction set is an unstandardized chaos, having on the order of a thousand individual quirks. Even the largest, best-cap- italized organizations have been able to cope with that, so that compiled code tends to be a wretchedly sub- optimal joke. The lessons of the old mainframes have yet to be learned. The upshot is that things that aren't done often enough to support multi- billion-dollar software companies are often best done on niche machines, especially if speed, large memory, or a GUI is desired, or interrupts are needed. Sure, a Lotus or a Microsoft can handle the problems caused by dozens of graphics drivers, dozens of extended memory drivers, more than 500 printer drivers, dozens of slightly different serial and parallel ports, hun- dreds of quirky BIOS variants, and hundreds or maybe thousands of hard-disk variants. The person who writes a specialized program for filter analysis and sells a few hundred cop- ies probably can't make it multi-com- patible, except by resorting to lowest-common-denominator user interfaces and sticking by a 640K memory model. Even then, it's never really certain that the program that runs on my PC will run on the PC next door — and getting it to print properly on the system next door is well nigh out of the question. So, what will become of those 60 million PC's, plus the Macs, Amigas, Ataris, and so on? It's sad, but hu- manity has been down this road be- fore, and we find that horse carts, though they were once as abundant proportionally simply aren't permit- ted on the freeway. Those computers aren't going to make it either, though some, notably the DOS PC. may well hang on for a long while as windows in some POSlX-OS/2-Windows-DOS- Sparc-Mac-PC-Amiga machine of the future. CAfter all, if it were worth the trouble, it wouldn't be all that hard to simulate an Apple or Commodore 64 of seven years ago on a 486 PC, high-end Mac, or high-end Amiga — faster than real time!) And that raises what should be the hottest issue of all. something far more important than ranting and rav- ing over doomed PC's versus doomed Macs versus doomed Amigas. The issue is our own data, which we must somehow get out of that DOS window and onto that ma- chine of the future — to say nothing of moving it from one application to an- other or to a supercomputer. We have allowed much of our data, en- tered laboriously and at tremendous expense, to become embodied in files that are formatted in obtuse, se- cret, and unstandardized ways. It is high time that the software manufacturers who practice this are forced to change. They are in effect thieves who have stolen from us what is rightfully our property. It is time to insist that all software that we buy have the capability to disgorge our data in full, including such things as the coordinates of graphical objects, in an open, published-data-inter- change format. As a symbolic dis- couragement to theft and extortion by software manufacturers, and to al- low third parties to assist in retrieving the stolen property without fear of litigation, it is time to amend the copyright law to explicitly permit re- verse engineering in any program that stores output but won 't provide it in an open format, irrespective of any and all language to the contrary in the licensing "agreement." We have been down this road be- fore. Compiler suppliers once swore that royalty-free function libraries would end the world. Much the same was said of ANSI-standard C, and of spreadsheet DIF files, and so on. Od- dly enough, the world is still here. So to any manufacturer who feels this proposal is unreasonable, I say this: Maybe your problem is that your are making money by holding your cus- tomers up for ransom, rather than by providing a good product. If so. the sooner you are out of business, the better — preferably on terms that are as punitive as possible to you, your investors, and your bankers. You are not indispensable, regardless of who you think you are or how big you are. There are hungry hordes waiting in the wings, ready willing, and eager to replace you in a twinkling. PAUL SCHICK Madison. Wl Regarding Ms. Abbot's letter and Larry Klein's response in the October issue, as an audio/video repair tech- nician who has attended mandatory factory-service seminars and who subscribes to several electronic mag- azines, 1 must agree with Ms. Abbot. Although service centers in my area charge a lower price for cleaning, they use head-cleaning tapes at that low price. For a more thorough, prop- er cleaning, they charge more. A Radio-Electronics article en- titled "Keep Your VCR Healthy" (March 1989) also supports Ms. Ab- bot's view and states, "We definitely do not recommend the use of any type of video-head cleaning cassette. It has been found that some of the cassette-type cleaners are actually "Plant a tree today for all the world to share" You can make life better for your children and for the future. Join me and plant a tree today for all the world to share. For your free brochure, write: Trees for America, The National Arbor Day Foundation, Nebraska City, NE 68410. John Denver for a The National Arbor Day Foundation abrasive to the video heads." While attending service seminars sponsored by Panasonic. RCA, and Samsung, the instructors stated that those companies void any warranties if head-cleaning cassettes have been used. The representative from Sam- sung mentioned the ability to use a high-grade tape with its built-in "chemical" cleaning (but not neces- sarily the recording part, just play it through), I, too, have found the older me- chanical VCR's to be more durable. The user can "punch" the keys and the machines can handle it. where the plastic inlays of the newer ones would snap apart and break. The newer electronic units also appear to be more susceptible to lightning strikes, power surges, and static discharge while just turning them on. Mr. Klein has presented a lot of good ideas and covered some inter- esting subjects in his column, and I won't stop reading him because of his reply to Ms. Abbot. Thanks for the opportunity to express my opinion and experiences. DAVE LEE Anoka, MN Call (800) 992-9943 Over 35,000 Electronic Components Call Today for Your FREE SUBSCRIPTION If You Order Today 3 :■:■:■ ■ ■-:-:-:-■ ■ -: Stocking Locations Across America, The "Great Deal" Catalog! a scott] By (siEmefson 286 AT COMPATIBLE COMPUTER WITH 40MB HARD DRIVE AND 14" VGA COLOR MONITOR Emerson, one of the biggest names in the business is closing out these Scott 286 AT Computers so our buyer was able to purchase the remaining quantities for an unbelievably low liquidation price! • €0286 microprocessor running at 12/6MHZ. (swrtchable). ■ 40MB IDE hard drive. • One MB RAM on motherboard. •One 3.5" 1.44MB floppy driva. • One 5-1/4* 1.2MB (loppy drive. •IBM compatible. • Slot for 80287 math co-processor. • 5-16 oit full tenglh expansion slots. • Two serial ports, one parallel port. • VGA multi-port video controller. •14" VGA, non-glare monftor, .41 dol pitch. • Resolution: 640 X 480. • 101 -key keyboard. • Software includes: MS DOS 3.31 In ROM. Ti > Pascal 5.0, Menu Program Manager, l_.iand Qualtro spreadsheet S PFS Professional Write word processing, • Model #: 2000SCI2F, ■ One Year Limited Mfr, Warranty! • Factory Newl Mfr. Sugg. Retail: $2,998.00 DAMARK$QQQ99 999 Item No. B-2634-16B631 SH $49.00 FOR FASTEST SERVICE, CALL TOLL FREE 1-800-729-9000 DAMAHK INTERNATIONAL, INC. 7101 Winnetka Ave. N., Minneapolis, MN 55-128- 1619 Please rush me: __ Scolt 286 AT Computers) @ S999.99 each, plus S49.00 s/h each. Item Mo. &-2634-168631 MN res. add 6^ sales tax. Name Address City. Stale, Zv □ ChocfcMO Can) No □ VISA □ MasterCard □ Dacovar Ex. Call? Ph»( 1 Signature CopyrigM 1931 DAMARK Iniemalkmai. Inc. AH i>ghEi DELIVERY TO 48 U.S. STATES ONLY CIRCLE 117 ON FREE INFORMATION CARD 11 No other training— anywhere— shows you service computers Now includes AT-compatible, 20 meg hard drive, and exciting new diagnostic package! Only NRI walks you through the step-by-step assembly of a powerful AT-compatible computer system you keep — giving you the hands-on experience you need to work with, troubleshoot, and service all of today's most widely used computer systems. With NRI at-home training, you get everything you need to start a money-making career, even a computer service business of your own. No doubt about it. The best way to learn to service computers is to actually build a state-of-the-art computer from the keyboard on up. And that's just what you do when you train with NRI. As you perform key tests and demonstrations at each stage of assembly, you see for yourself how each part of your computer works, what can go wrong, and how you can fix it. Only NRI, the leader in career- building electronics training for more than 75 years, gives you such practical, real-world computer servicing experience. Indeed, no other training — in school, on the job, anyiohere — shows you how to troubleshoot and service computers like NRI. You get in-demand computer skills as you train with a powerful AT-compatible computer system — now with 1 meg RAM and 20 meg hard drive With NRI's exclusive hands-on training, you actually build and keep the powerful new AT-compat- ible West Coast 1010ES computer, complete with 1 meg RAM and 20 meg hard disk drive. You start by assembling and testing the "intelligent" keyboard, move on to test the circuitry on the main logic board, install the power supply and 5- 1 /*" high-density floppy drive, then interface your high- resolution monitor. But that's not all. Your NRI hands-on training continues as you install a powerful 20 megabyte hard disk drive— today's most- wanted computer periphe ral — included in your course to dra- matically increase your computer's data storage capacity while giving you lightning-quick data access. DIGITAL MULTIMETER Professional test instrument for quick and cisj' circuit measurements. % II) HARD DISK DRIVE The 20 megabyte hard disk drive you install internally gives you greater data storage capacity and access speed. AT-C0MPATI8LE COMPUTER 80286 CPU [12 MHZ clock, wait stales), I racg RAM (expandable to 4 meg), 1.2 meg high-density floppy disk drive. ^rV«S LESSONS Clcarcut, illustrated tests build your understanding of computers step by step. SOFTWARE If am to use MS-DOS, GW-BASIC, and the popular new Microsoft 1 Works integrated software package, New! Training now includes Ultra-X diagnostic hardware and software for quick, accurate troubleshooting! Now NRI takes your hands-on computer servicing experience an important step further: Now you train with and keep the remarkable R.A.C.E.R. plug-in diagnostic card and QuickTech diagnostic software from Ultra-X — professional diagnos- tic tools that make computer troubleshooting fast and accurate. Using these state-of-the-art tools, you learn to quickly identify and service virtually any computer in school, on the job, how to troubleshoot and like NRI MONITOR High-resolution, nonglarc. 12* TIL monochrome monitor with till and swivel DISC. TECHNICAL MANUALS You gel "inside" your AT-compatiblc computer sysicm with exclusive NRI Training Kit Manuals plus technical specs direct from the manufacturer. DISCOVERY LAB Complete bread boarding system to let you design and modify circuits, diagnose and repair faults. DIGITAL LOGIC PROBE Using your logic probe, you get firsthand experience analyzing digital circuit operation. problem on XT, AT 80286/80386, and compatible machines. You discover how to use the R.A.C.E.R. card to identify individual defective RAM chips, locate interfacing problems, and pinpoint defective support chips. Plus you learn to use your QuickTech diagnostic soft- ware to test the system RAM and such peripheral adapters as parallel printer ports, serial communica- tions ports, video display memory, and floppy and hard disk drives. Only NRI gives you such confi- dence-building, real-world experi- ence. Only NRI gives you both the knowledge and the professional tools to succeed as today's in- demand computer service technician. No experience needed... NRI builds it in You need no previous experience in comput- ers or electronics to succeed with NRI. You start with the basics, following easy- to-read instructions and diagrams, moving step by step from the fundamentals of electronics to sophisti- cated computer servicing techniques. With NRI's unique Discovery learning Method, you're sure to get the kind of practical, hands-on experience that will make you fully pre- pared to take advan- tage of every opportu- nity in today's top- growth computer service field. You learn at your own conve- nience, in your own home. No classroom pressures, no night school, no need to quit your present job until you're ready to make your move. And all throughout your training you've got the full support of your personal NRI instructor and the entire NRI technical staff, always ready to answer your questions and help you achieve your training goals. Your FREE NRI catalog tells more Send today for your free, full-color catalog describing every aspect of NRI's innovative computer training, as well as hands-on training in video/ audio servicing, telecommunications, industrial electronics, and otiier growing, high-tech career fields. If the coupon is missing, write to NRI School of Electronics, McGraw-Hill Continuing Education Center, 4401 Connecticut Avenue, NW, Washington, DC 20008. AT is a registered trademark of International Business Machines Corporation. R.A-CE.R. and QuickTech arc registered trademarks of Ultra-X, Inc SEND TODAY FOR FREE CATALOG Schools McGraw-Hill Continuing Education Center 4401 Connecticut Avenue, NW, Washington, DC 20008 m CHECK ONE FREE rU For career courses ] approved under GI Bill. check for details. CATALOG ONLY PI Microcomputer Servicing Q TV/Yidco/Audio Servicing G Telecommunications Indus [rial [ilea runic;. ■& Robotic;. G Security Electronics □ Electronic Music Technology O Basic Electronics □ Computer Programming □ PC Systems Analysis D PC Software Engineering Using C L\ Desktop Publishing & Design U2 Word Processing Home Business □ Paralegal □ Fiction/Non fiction Writing □ Automotive Servicing D Building Construction D Air Conditioning, Healing, & Refrigeration D Electrician G Small Engine Repair □ Locksmithing D Bookkeeping & Accounting Name (please print) Age Address City/State/Zip Accredited Member. National Home Study Council 3-071 DIGITAL VIDEO STABILIZER ELIMINATES ALL VIDEO COPY PROTECTIONS While watching rental movfK, you Will nollce an- noying periodic color dark*nlntj, color shifl. un- wanted lines, flashing Of jagged edges. This is caused by tht copy projec- tion jamming signals em- bedded in the vtdeo tape, such as Macroviston copy protection Digital Video Stabilizer; RXII completely eliminates all copy protec- tions and jamming signals and brings you cryslal clear pictures. FEATURES: • Easy to use and a snap to install • State-of-the-art irv teg rated circuit technol- I100%« 10O% automatic - no need for any troublesome adjust- ments # Compatible to all types of VCRs and TVs •The best and most excit- ing Video Stabilizer in the market • Light weight (3 ounces) and Compact f 1 k3„5k5 ) • Beautiful deluxe gift box • Uses a standard 9 Voll battery which will last 1- 2 years. WARNING : SCO Electronics and RXII dealers do not encourage people to use the Digital Video Stabilizer to duplicate rental movies or copyrighted video tapes. RXII is in- tended to stabi- lize and restore crystal clear picture quality for private home use only. ( Dealers Welcome ) ToOrder: $49,95 M + $4 lor fast ups shipping 1-800-445-9285 or 516-568-9850 Visa, M/C, COD M-R 9-6 (battery not Included) SCO ELECTRONICS INC. DaptCRE7 581 W. Merrick Rd. Valley Stream NY 11580 Unconditional 30 days Money Back Guarantee CIRCLE IBS ON FREE INFORMATION CARD 16 CABU DESCRAMBLER How You Can Save Money: 1 lion Cable Rental Fe« USCable will Beat Anyone's Price Advertised in Ihls Magazine! 1 Unit 5 + Jerrol J S B w/Tri-Ri $99 J70 SuperTri-Bi (TBM) J109....S75 Jerrold 450 combo tl8»...S139 Scienti Tic Atlanta.., S109....S75 SA 85% S2£Q.,..$m Pioneer. ..—*,„„.„„„ j 109, . . ,S79 OakKN12(w/VS) J109...J6S Hamlin MI.D 1200.... S89. S59 Tocora $169....S129 Stargale converter...-.,.. 189. S69 Panasonic TZPC145 $99. S79 30 Days Money Back Guarantee Free lfi page Catalog Visa, M/C, COD or send money order to: US Cable TV Inc. D ep t kre? 41 00 N.Powerline Rd., Bldg F-4 Pom pa no Beach, FL 33073 1-800-445-9285 For Our Record 1, ibe undersigned, do hereby declare under penalty of per- jury that all products purchased, now and in the future, will onry be used on Cable TV systems with proper authorization From local officials or cable company officials in accordance with all applicable federal and state laws. FEDERAL AND VARIOUS STATE LAWS PROVIDE FOR SUBSTANTIAL CRIMINAL AND CIVIL PFNALTIES FOR UNAUTHORIZED USE. Date: Signed: No Florida Sales! FOILED BY COILS The project entitled "Build This Magnetic Field Meter" (Radio- Electronics. April 1991) brought to mind a difficulty I have always had with the archaic "art" of coil winding. Factory-made coils are constructed using highly specialized jigs and fix- tures, so that their specified values are usually reliable. Since the average hobbyist is equipped with a maximum of two hands, it is not illogical to pre- sume that a fairly complex home-built device is required to lay down mag- netic wire on a coil form with accept- able results. (Acceptable, to me, means rigidly anchored, evenly spaced windings that conform to 95% of a comparable factory stan- dard. In other words, why stuff a cir- cuit board with high-quality silicon if the interfacing discrete components are not approximately equal in quality reliability?) The one-meter-long coil shown in Fig. 6 of the article raises my coil- winding hackles to a fever pitch! The extremely wide variations in toler- ance that would surely result from fabricating that elephantine coil makes me wonder about using that EARN YOUR B.S.E.E. THROUGH HOME STUDY Our Mew and Highly Effective Advanced-Place- ment Program for experienced Electronic Tech- nicians grants credit for previous Schooling and Professional Experience, and can greatly re- duce Itie time required to complete Program and reach graduation. No residence schooling re- quired (or qualified Electronic Technicians. Through this Special Program you can pull all of Ihe loose ends of your electronics background together and earn your B.S.E.E. Degree. Up- grade your status and pay to the Engineering Level. Advance Rapidly! Many finish in 12 monlhs or less. Students and graduates in all 50 States and throughout the Wortd. Established Over 40 Years! Write for free Descriptive Lit- erature. COOK'S INSTITUTE OF ELECTRONICS ENGINEERING J*Ens Rise Time » X-Y Operation • Z Axis • Delayed Triggering Sweep • Includes 2 P-1 Probes All scopes include probes, schematics, operators manual and 3 year (2 yrs for EEenco scopes) world wide warranty on parts & labor. Many accessories available for all Hitachi scapes. Call or write lor complete specifications on these and many other fine oscilloscopes. FREE DMM with purchase of ANY SCOPE SCOPE PROBES P-T 65MHz, Ix, I Ox $19.95 P-2 100MHz, Ix, lOx $23.95 B + K TEST EQUIPMENT All Models Available Call for special price Digital Capacitance Meter HftfB CM-1550B $58.95 9 Ranges .1pf-20,OOOuld .5% basic accy. Zero control ai Case Big V Display Digital LCR Meter LC-1801 $125 Measures: Coils 1uH-200H Caps .1pf-2D0jl Res .Q1-2DM Multimeter with Capacitance a Transistor Tester $55 CM-1500B Reads Veils, Ohms C i. •■ .:■ 1 1 . Capacitors, Transistors and Diodes ' with case Big 1" Display FLUKE MULTIMETERS All Models Available Call for special price Quad Power Supply XP-580 2-2Q V @ 2A 12V @1A 5V@3A -5V@,5A Fully regulated and shod circuit protected Triple Power Supply XP-620 Assembled $65 Kit $« 2 to 15V @ 1A, -210 -1SV@ 1A (or 4 to 30V @1 A) and 5V @ 3A All the dssired leatures for doing experiment. Features short circuit prelection, all supplies AM/FM Transistor Radio Kit with Training Course Model AM/FM 1 0B $26.95 1 4 Transistors + 5 Diodes Makes a great school pro|ecl True RMS 4 1/2 Digit Multimeter M-7000 $135 .05% DC Accuracy .1% Resistance with Froq. Counter and Deluxe Case GF-8016 Function Generator with Freq. Counter $249 Sino, Sq : uaro, Triangle Fulss. Ramp, ,2lo2MHz Freq Counter .1 - 10MHz GF-8015 without Freq. Meter $179 *Ti* Function Generator BIox #9600 $28.95 Provides sine, triangle, square wave Irom 1Hz 10 1MM7 AM orFM capability Learn to Build and Program Computers with this Kit Includes: All Parts, Assembly and Lesson Manual Model MM-8000 Wide Band Signal Generators $129.00 Starting from scratch you build a corn pfcate system. Our Micro-Master trainer teaches you to write into RAMs. RQMe and run a 0085 mienspfocassor, which uses simitar machine language as IBM PC. Robotics Kit for above (MMBOIO) 71 .95 WE WILL NOT BE UNDERSOLD! UPS Shipping: 48 States 5% ($3 Min $10 Max) Shipping IL Res., 7% Tax FAX: 70B-520-008S SG-9000 $129 RF Freq 100K-450MHZ AM Modula- lion ol 1KHz Variable RF oulpul SG-9500 ml Digital Display & 150MH2 built-in Counter S249 XK-500 DIGITAL / ANALOG TRAINER A ccrnpioio mint-Fob tor building, testing, prototyping analog and digital circuit) EKtnca's Pigflal / Analog Trainer ts specially dssSgdod far school pro|6clS, with 5 built-in power vrppltes. Indvdat a Function oonoratoj with canllngualp variable, sine. triangutai, square wavO lorms. Alt power 5uppli« are cogwUtlQC end protoctDd HQOinzt shorts. POWER SUPPLIES ♦ VariatfoPowflrSwppty **l35i0£tWDC3 3Amp (-1 25 ti 15VOC © 1 Amp] . -1.25 10 -20V DC # .5 ATC il-l.-ZS to -15VDC4S> 1 AiTflf. * k12VDC# i .*T,n • -12V0C6? I Amp • -*5VOC® lAmp *30WAC C**ir*r I4PPKI # iSVAC dtMnp ANALOG - SECTION ■ Fwtdion Gictraior Sine Tiiangulir, Soxura wivalormi * Frsouunsy aajLiblary* In lrv» fanoei mm 1 Id 10DKHZ • Fir* tnqjtncf idj-Jti ■ Arr^Jrl jtjq ytuil ■ ModulalkmFM-AM DIGITAL- SECTION ■ mpn iiwi bwmiIw ■ Two no bounce >og« wmcOoi ■ Eighc LED rtadouis TTL ELfllflrad ' OaA i ■c'^ja 'i^-r 1 lo i Z »i i * CtocV arnqWui* WPP aquir« wave El HEADBOARDS > 3 As rj;:.*-*: jr-:!i 9i(t\ :;■: -Urn: H0ba>pDHf'lKiM1^K|] C & S SALES INC. 1245 Rosewood. Deerfietd. II. fif)IH5 I8lllli:'>a-77ll 1 70S i 541-1171(1 CIRCLE 109 ON FREE INFORMATION CARD 5 17 COMMUNICATIONS AOR Scanners. Great Performance. Great Service. Great Value. Free Freight 25-Day Money-Back Guarantee Toll-Free Service and Support No Credit Card Surcharge One Year Warranty AR950 $239 AR1000 $399 CO O z O cc t3 UJ _J UJ 6 Q < K. 18 1000 Channels. 8-600MHz, 805-1300MHz Standard Features: ■ Extremely compact size. ■ Continuous coverage (except UHF TV 600-805) ■ Antenna attenuator switch, lOdb. • Manual tuning knob. • Earphone jack, 3.5mm. ■ AM, FM and wide band FM tuning modes. ■ Backlighted LCD display. ■ 10 Scan Banks, 10 Search Banks. ■ Selectable Priority Channel. • Delay, Hold Features. • Selectable Search Increments, 5-955KHz. • Permanent memory backup, • 4 AA Ni Cad batteries included. • AC adaptor/charger. • Carry Case. ■ Cigarette Lighter Charger. • Belt Clip. ■ Earphone. Options: External Speaker. Mobile Mount. Extended Warranty. 2/3 yrs Specifications: Coverage: Sensitivity: Speed: IF: Increments: Audio: Power: Antenna: Display: Dimensions: MS190 $19.50 $45/$55 8-600, 805,1300MHz .35uV NFM, l.OuV WFM, LOAM 20 ch/sec. scan. 40 ch/sec. search 561.225, 58.075, 455KHz or 10.7MHz 5 to 955KHz selectable/ 5 or 12,5 steps. ,4 Watts Input 9 - 13.8 V. DC BNC LCD 6 7/8H x 1 3/4D x 2 1/2W. 12oz wt. 100 Channels. Low, Air, High, UHF & 800MHz. Standard Features: - Extremely compact size. ■ Unrestricted 800MHz coverage. ■ 100 channels permanent memory. ■ Earphone Jack & Attenuator. ■ Delay, Hold features. ■ Channel 1 Priority. • 5 Scan Banks, 5 Search Banks. • Telescopic and Rexible Antennas w/ BNC connector, - AC & DC Power cords w/ mtng hardware. ■ One Year Limited Warranty. Options: Base type antenna 25 to 1000MHz w 50' coax. AS300 $59.95 Mag Mnt Mobile Antenna. 15' coax. MAI 00 $25.00 Cigarette Lighter power adaptor. CP100 $4.00 External Speaker with mobile mount, MS100 $19.50 Extended Warranty. 2/3 yrs $40/$55 Specifications: Coverage: Sensitivity: Scan Speed: IF: Increments: Audio: Power: Antenna: Display: 27-54, 108-174, 406-512, 830-950MH.Z .4uV Lo,Hi. .8uV Air. ,5uV UHF. l.OuV 800 15 ch/sec. 21.4MHz, 455KHz 10,12.5,25,30 1W 12.8VDC, 200MA BNC LCD w/backlight Dimensions: 2 1/4H x 5 5/8W x 6 1/2D. 14oz wt. We offer lOO's of communications products. CIRCLE 181 ON FREE INFORMATION CARD COMMUNICATIONS AR2500 $499 2016 Channels. 1 MHz to 1500 MHz Standard Features • Continuous coverage • AM, FM, wide band FM, & BFO for SSB, CW. • 64 Scan Banks. • 16 Search Banks. • RS232 port built in. • Includes AC/DC pwr crd. Antenna, Mntng Brckt. •One Year Limited Warranty. Options: Earphone. EP2O0 $2.00 External Speaker. Mobile Mount. MSI 90 $19.50 Extended Warranty. 2/3 yrs. $65/75 Mobile Mounting Bracket. MM! $14.90 RS232 Control Package SCS2 $295.00 (software & cable) offers spectrum display and database. Specifications: Coverage: 1 MHz - 1500MHz Sensitivity: .35uV NFM, l.OuV WFM, 1.0AM/SSB/CW Speed: 38 ch/sec. scan. 38 ch/sec. search IF: " 750.00, 45.0275, 5.5MHz 455KHz Increments: 5,12,5,25 KHz Audio: 1.2 Watts at 4 ohms Power: Input 13.8 V. DC 300mA Antenna: BNC Display: LCD, backlighted. Dimensions: 2 1 /4H x 5 5/8W x 6 1 /2D Wt. 1 lb. AR3000 $995 400 Channels. lOOKHz to 2036MHz. Standard Features: • Extremely compact size. • Continuous coverage • Attenuation Programmable by Channel. • Manual tuning knob. •Tuning increments down to 50Hz. • AM, FM, wide band FM, LSB, USB, CW modes. • Backlighted LCD display. •4 Scan and Search Banks, Lockout in Search. • 4 Priority Channels. • RS232 control through DB25 connector. • Delay, Hold Features. • 15 band pass filters, GaAsFET RF amp. • Sleep and Alarm Features. •AC adaptor /charger. DC power cord. •Telescopic Antenna. Options; Earphone. EP200 $2.00 External Speaker. Mobile Mount. MSI 90 $19.50 Extended Warranty. 2/3 yrs. $65/75 Mobile Mounting Bracket. MM1 $14.90 RS232 Control Package SCS3 $295.00 (software & cable) offers spectrum display and database. Specifications: Coverage: lOOKHz- 2036MHz Sensitivity: .35uV NFM, l.OuV WFM, 1.0AM/SSB/CW Speed: 20 ch/sec. scan. 20ch/sec. search IF: 736.23, (352.23) (198.63) 45.0275, 455KHz Increments: 50Hz and greater Selectivity: 2.4Khz/-6db (SSB) 12KHz/-6db (NFM/AM) Audio: 1.2 Watts at 4 ohms Power: Input 13.8 V. DC 500mA Antenna: BNC Display: LCD Dimensions: 3 1 /7H x 5 2/5W x 7 7/8D Wt. 21b lOoz. To Order Call 1 • 800 • 445 • 7717 In All 50 States and Canada. 24 Hours a Day. Fax Orders: 1-800-448-1084, 24 Hours a Day. ACE Communications Monitor Division 10707 E. 106th Street, Fishers, IN 46038 Inf 1 Voice* 317-842-7115. IntT Fax# 317-849-8794. Service and Support Lines: Mon-Fri 9a.m. to 9p.m., Saturday 10-4. EST MasterCard, Visa, American Express, Checks, Approved P.O.'s. & C.O.D. (add 5.00) Prices ana specifications subject to change. CIRCLE 181 ON FREE INFORMATION CARD 1S EQUIPMENT REPORTS Fluke Model 79 DMM CO o z o fit p o o Q < 20 As technology advances, it's easy to become accustomed to (read: spoiled by) the new features and capabilities that become possible in test equipment. Take, for example, the digital multimeter. We've become so used to having our 4-digit DMM stuffed in our hip pocket that we don't always appreciate how much things have changed in the last 15 years or so. Back then, DMM's were still con- sidered somewhat exotic. If you were lucky enough to have access to one, it was on a test bench somewhere. The handheld multimeter didn't make an appearance until Fluke (John Fluke Manufacturing Company, Inc. P.O. Box 9090, Everett, WA 98206-9090; 206-347-6100) intro- duced their model in 1976. Although we're sure that some of our younger readers never knew a world without DMM's, most of us can remember the excitement with each new intro- duction and improvement. Of course, we also remember the analog vs. dig- ital battles that are, in some quarters, still going on between the respective proponents. In 1983, Fluke introduced their 70 Series handheld DMM's. Since then, they've sold some 2 million units. (According to the manufacturer, Fluke sells a 70-Series meter "every minute of every day.") What do you do when you have a family of DMM's that are obviously well liked, but that are almost ten years old? If you're Fluke, you introduce a "new-and -improved" 70 Series, and call it the 70 Series II. The new series consists of enhanced versions of five models in the original 70 Series, and three new models. The meters retain the well-known styling of the origi- nals, especially the single off-center rotary selector that makes one-hand- ed operation comfortable. The model 79 We examined one of the all-new meters, the model 79. As the high- end meter in the series, the 79 also has the highest price: $185. (The lowest priced meter in the series, CIRCLE 10 ON FREE INFORMATION CARD Updating a classic line of digital multimeters which is also the lowest-priced meter Fiuke has ever sold, is the model 70, for $69.) The model 79 features a 4-digit, 4000-count display, and a 63-seg- ment analog bargraph. DC voltage is measured over six ranges (40 mV-4000 V), with a basic accuracy of 0.3%. As with all other modes, the ranges can be manually or automat- ically selected. AC voltage is mea- sured over five ranges (400 mV-4000 V), with a basic accuracy of 1.0%. AC and DC current are measured over four ranges up to a high limit of 10 amperes. Basic accuracy is 0.5% DC, and 1.5% AC. Resistance is measured over seven ranges (400 ohms-40 megohms) with a basic ac- curacy of 0.4%. The model 79 also offers a fre- quency-counter mode that is capable of measuring from 1 Hz to more than 20 kH2 with an accuracy of 0.01%. Interestingly, the meter offers a 9999- count display in the frequency mode. Even more interesting is that the bar- graph portion of the display will show the AC voltage whose frequency is being measured while the digital dis- play shows the frequency. Capacitance measurements are also possible, from 10 pF to 999.9 p,F with an accuracy of 1.9%, and from 999.9 (jlF to 9999 jlF with an ac- curacy of 1 0% . A diode-test feature, audible con- tinuity beeper, and automatic sleep mode are standard on all meters in the 70 Series II, as is Touch Hold. Fluke's method of capturing stable signals and holding the display so that you can keep your eyes on your test points instead of on the meter. Each new reading automatically re- sets the Touch Hold "memory" so that you don't have to take your hands off your probes, either. Another feature featured on the model 79 is "Smoothing," which dis- plays a running average of eight read- ings so that even unstable signals can produce stable displays. (The bar- graph , however, will show that the sig- nals are unstable.) The model 79 also offers a low- ohms range, which provides 0.01- ohm resolution. Zero calibration is also available. The meter has an elegant design. Aside from the eight-position func- tion selector, there is only one other control: a push button in the center of the rotary switch. The push button takes on different functions depend- ing on how long it's held down. Tap it lightly, and you put the meter in the manual-ranging mode. Tap it again quickly, and you change the meter's range. If you hold the button down for one second, you put the meter back in the autorange mode. If you're in the con- tinuity position, holding the button for one second puts the meter in the low- ohms mode. If you hold the center button for two seconds, the meter is put in the Touch- Hold mode, or, if you're in the continuity mode, you put the meter in the diode-test mode. Alternatively, in the resistance mode, the meter en- ters the capacitance mode. On paper, that might sound con- fusing. In use, however, it's quite sim- ple. And. even if you forget how it works, a well-designed front-panel makes it obvious. Overall, were quite impressed with the 70 Series II multimeters. Judging from these new-and-im- proved models, we can hardly wait for Fluke's 80 Series to get a little older! RE Electronics \KMMpIM^. THE MODEL WTT-20 IS ONLY THE SIZE OF A DIME, yet transmits both sides of a tele- phone conversation to any FM radio with crystal clarity. Telephone line powered - never needs a battery! Up to Vi mile range. Adjusta- ble from 70-130 MHZ. Complete kit $29.95 + $1.50 S + H. Free Shipping on 2 or more! COD add $4. Cati or send VISA. MC, MO. DECO INDUSTRIES, Box 607, Bedford Hills, NY 10507. (914) 232-3878. CIRCLE 127 ON FREE INFORMATION CARD 3«S£5r^ COMPUTER KITS, BOARDS & COMPO- NENT PARTS. Designed to the highest de- gree of quality and reliability available today. They're fun, easy to build, educational. IBM compatible, very powerful, and at great prices. All items are pre-tested, include a full year warranty, step by step assembly manual, and free tech support. Assembly available at no extra charge. For free catalog contact: GENERAL TECHNICS, P.O. BOX 2676, LAKE RONKONKOMA, NY 11779, or call (516) 981-9473. VISA, MasterCharge. Ameri- can Express. COD- CIRCLE 183 ON FREE INFORMATION CARD FREE CATALOG! ELECTRONIC TOOLS & TEST EQUIPMENT. Jensen's new Master Catalog, available free, presents major brand name electronics tools, tool kits, and test in- struments, plus unique, hard-to-find products for assembly and repair and custom field ser- vice kits available only from Jensen. All fully described and illustrated. Enjoy free technical support and rapid, post-paid delivery any- where in the Continental USA. JENSEN TOOLS INC., 7815 S. 46th St., Phoenix, AZ 85044. Phone; 602-968-6231; FAX: 1 -800-366-9662. CIRCLE 115 ON FREE INFORMATION CARD ELEVEN-PIECE RACHET TOOL KIT Includes reversible ratchet handle, extension bar, six bits, two precision screwdrivers, and a cutter. Comes in fitted case. Get one for your shop, another for your car, another for your tool kit. To order send $11.75 USA shipping only. ELECTRONIC TECHNOLOGY TODAY INC., PO Box 240, Massapequa Park, NY 11762-0240. CABLE TV CONVERTERS AND DE- SCRAMBLERS SB-3 $79.00 TRI-BI $95.00 MLD-S79.00 M35B $69.00 DRZ-DIC $149.00. Special combos available. We ship COD. Quantity discounts. Call for pricing on other products. Dealers wanted. FREE CATA- LOG. We stand behind our products where others fail. One year warranty. ACE PROD- UCTS. P.O. Box 582, Saco, ME 04072 1 (800) 234-0726. CIRCLE 75 ON FREE INFORMATION CARD CALL NOW AND RESERVE YOUR SPACE • 6 x rate $940.00 per each insertion. • Fast reader service cycle. • Short lead time for the placement of ads. • We typeset and layout the ad at no additional charge. Call 516-293-3000 to reserve space. Ask for Arline Fishman. Limited number of pages available. Mail materials to: mini-ADS. RADIO-ELECTRONICS, 500- B Bi-County Blvd., Farmingdale, NY 11735. FAX: 516-293-3315 APPLIANCE REPAIR HANDBOOKS— 13 volumes by service experts: easy-to- understand diagrams, illustrations. For major appliances (air conditioners, refrigerators, washers, dryers, microwaves, etc.), elec. housewares, personal-care appliances Basics of solid state, setting up shop, test instruments, $2.65 to $7.90 each. Free brochure. APPLIANCE SERVICE, P.O. Box 789, Lombard, IL 60148. (708) 932-9550. CIRCLE 84 ON FREE INFORMATION CARD SIMPLY SNAP THE WAT-50 MINIATURE FM TRANSMITTER on top of a 9v battery and hear every sound in an entire house up to 1 mile away! Adjustable from 70-130 MHZ. Use with any FM radio. Complete kit $29.95 + $1.50 S + H. Free shipping on 2 or more! COD add $4. Call or send VISA, MC, MO. DECO INDUSTRIES, Box 607, Bedford Hills, NY 10507. (914) 232-3878. CIRCLE 127 ON FREE INFORMATION CARD C 21 2SZ3E Use the Free Information Card for more details on these products. o z o CC F- O LU El Q D < FUNCTION GENER- ATOR. For engineers who occasionally need to create their own waveforms, the Philips PM 5139 function generator from John Fluke offers both an arbitrary waveform -prog ramming fa- cility via IEEE-488 bus and general-purpose functions in a single instrument. The instrument allows the engi- neer to create servo drive waveforms, acoustic and sonar bursts, mechanical waveforms for bump test- ing and simulation, and brain and heart waves, among others. Its arbitrary waveform facility allows the PM 5139 to play back a custom-design waveform when and where it is needed and, if required, subject it to any of the modulation modes: AM, FM. gating, bursts, phase shift keying, and linear or logarithmic frequency sweeps. Six different arbi- trary waves can be loaded into memory and individu- ally selected: within about 70 ms. the new arbitrary wave is available at the gen- CIRCLE 16 ON FREE INFORMATION CARD erator output. Instead of the standard rotary switches, knobs, and pushbuttons found in classic benchtop function generators, the PM 5139 offers a logical array of pa- rameter-selection and con- trol keys along with one rotary knob. To make a nu- merical setting, the user touches the relevant key and actuates the rotary knob to dial in the correct readings. All manual set- tings can also be achieved by remote control across the IEEE-488 bus. All pa- rameters — frequency, waveform, amplitude, off- set, and modulation — are shown on a single, large, backlit LCD readout. The PM 5139 features a very flat amplitude re- sponse and an accuracy to within ±2 ppm over the complete 0.1 -MHz to 20- MHz frequency range. In the low-frequency range, five of the ten standard waveforms can be varied in duty cycle from 1 % to 99% with a 1% resolution and ±0.1% accuracy. The PM 5139 has a base U.S. list price of $4190, or $4690 with a GPIB.— John Fluke Mfg. Co., Inc., P.O. Box 9090, Ever- ett, WA 98206; 800-44- FLUKE. 386 SINGLE-BOARD COMPUTER. Rapid Sys- tems' PX1260 is a high- speed, high-performance, 33-MHz, 386-based CPU module for the PCXI "PC Extended forlndusty" EISA "Extended Industry Stan- dard Architecture" passive backplane. Intended for ap- plications in EISA worksta- tions, production tests, modular rugged PC's, fac- tory automation, and net- works, the PCXI is a modular, industrial PC based on a 13-slot passive backplane. The plug-in CIRCLE 17 ON FREE INFORMATION CARD CPU module features a 3'/2-inch floppy drive; an optional integrated 40- megabyte hard-disk drive is available. The PX1260 is based on a single-board computer and is com- pletely enclosed in a metal chassis to shield EMI/RFI emissions. Two serial com- munication ports, one par- allel port, and the 3'/2-inch floppy drive, along with the keyboard connector and reset button, are located on the front of the module for easy access. The PX1260 costs $5995 —Rapid Sys- tems, Inc.. 433 North 34th Street. Seattle. WA 98103; Phone: 206-547-8311; Fax: 206-548-0322. INDICATING FUSE. An in- novation in fuse technology used in the 2 AG indicating Slo- Bio fuse from UttleFuse, Inc. provides in- stant identification of an open (blown) fuse. Under normal operating condi- tions, the ruse's glass body is transparent; when the fuse blows, the body dra- matically darkens to a yellow/brown color, taking the guesswork out of blown-fuse identification and eliminating time-con- suming circuit testing. The 2AG Indicating Sio-Blow CIRCLE 18 ON FREE INFORMATION CARD can also be used to aid in design testing by showing a slight discoloration of the glass body if the current rating of the selected fuse is too low. The fuse pro- vides the same quality and performance charac- teristics as the standard 2AG fuse. It is available with axial leads or in the cartridge style. A complete assortment of mounting accessories, including fuse blocks, panel-mount, or in- 22 Learn to Use Your Computer's Full Potential, New Career * Course from * CIE! TfTl If you've been hesitating about upgrading your computer skills because you couldn't find the time or locate the right program to teach you everything you need to know to be successful in today's world of computers, you'll be happy to hear that CIE's new career course can provide you with the computer technology curriculum you seek in an independent study program you can afford to invest your time in. CIE's COMPUTER OPERATION and PROGRAMMING course was designed and devel- oped by CIE to provide a complete overall under- standing of the unlimited potential today's computers offer, once you learn and discover their full capabili- ties, in today's high tech environment. CIE's new computer course quickly provides you with the electronics fundamentals essential to fully understand and master the computer's technological potentials for your personal and professional advancement. Upon mastering the fundamentals you will move into high level language programming such as BASIC and C-Language and then use that programming in order to relate the interfacing of electronic hardware circuitry to programming software. As a gradu- ate of the Computer Operation and Programming course, you will be able to successfully understand, analyze, install, troubleshoot, program and maintain the various types of electronic equipment used in business, manufac- turing, and service industries. Since 1934, CIE has been the world leader in home study electronics by providing our 1 50,000- plus graduates with the curriculum and hands-on training they've needed to become successful in today's highly competitive and computer oriented society. As a CIE student you'll receive a first rate education from a faculty and staff with only one desire. Your future success! We encourage you to look, but you won't find a more comprehensive computer course anywhere! And it's a course designed to fit around your lifestyle and commit- ments today, so you can be assured of professional successes and financial gains tomorrow. Please, do yourself a favor and send the attached card or fill out and mail the coupon below for more information about CIE's Computer Operation and Programming course. Do It Today! Computer not included with course d YES! I want to get started. Send me my CIE school catalog including details about the Associate Degree program (for your convenience, CIE will have a representative contact you - there is no obligation). :Na r rint Name . Address City Apt. State. .Zip Age. Area Code/Phone Nc Check box for G.I. Bulletin on Educational Benefits □ Veteran CLEVELAND INSTITUTE OF ELECTRONICS l776Easl ITlhSlrctM Cleveland, Ohio 44I 14 {216)7E!-9400 O Active Duty A school of thousands. A class of one. Since 1 934. AE18 c 5 to 25 w o z o DC F o o < ir line fuse holders and sur- face-mount clips are also available. The 2AG Indicating Slo- Blo fuse costs 380 in 5- piece quantities for car- tridge types, 540 in 100- piece quantities for the ax- ial lead style. — Lit- teffuse, Inc.. 800 East Northwest Highway, Des Plaines. IL 60016; Phone: 708-824-1188. VIDEO FRAME GRAB- BER. Two video digitizing systems for IBM-compati- ble computers are available from IDEC inc. The Supervision/8 is a '/fee-sec- ond image-capture system that lets users acquire a black-and-white image in 256 gray- scale levels using simple software controls. It consists of a half-size card that plugs into any slot and CIRCLE 19 ON FREE INFORMATION CARD menu-driven software. The image is captured with a resolution of 256 pixels by 244 lines, and can be dis- played on any HGC, CGA, EGA, and VGA monitors. The Supervision/8 is com- patible with IBM-compati- ble PC/XT/AT or 386 systems. The Supervision/ '16 (pic- tured), compatible with AT- compatible computers, has picture resolution of 512 pixels by 488 lines, with 256 shades of gray, and captures images in /30 second. With a super-VGA display, the picture rivals black-and-white TV-broad- cast quality. The choice of display has no effect on the print quality, since the printed image is printed di- rectly from the disk file im- age, not from the screen. Its high resolution makes the Supervision/16 suit- able for scientific and engi- neering applications such as machine vision, inspec- tion, medical imaging, and security. Both video-frame grab- bers provide automatic cal- ibration of brightness and contrast, adjustable by the user. Images can be saved and recalled, printed out, or incorporated into docu- ments using Pagemaker, Ventura Publisher, or any other compatible Gray Scale Graphics Program. Both packages contain the interface card, software on disk, owner's manual, and a one-year warranty. The Supervision/8 is available in kit form for $169.95 (plus shipping and handling) and $269.95 fully assembled: the Supervision/16 costs $369.95. (Shipping and handling, and 6% sales tax in Pennsylvania, are addi- tional.)— IDEC, Inc., 1195 Doylestown Pike. Quaker- town, PA 18951; Phone: 215-538-2600: Fax: 215-538-2665. BENCHTOP DC POWER SUPPLIES. Understand- ing that not all engineers require high-end instru- ments on their benches, Hewlett-Packard has intro- duced two affordable, gen- eral-purpose benchtop DC CIRCLt 20 ON FREE INFORMATION CARD power supplies. Models E3610A (pictured) and E361 1A both feature a high- performance linear design with ripple and noise less than 200 mV rms. The 30- watt power supplies fea- ture dual-range outputs and CV/CC operation: CV mode for devices requiring a constant voltage and CC for those requiring a con- stant current. Mode crossover occurs automat- ically On the HP E36I0A, range 1 is 8V/3Aand range 2 is 15V/2A. The HP E361 1A's range 1 is 20V/1.5A and range 2 is 35V/0.85A. For ease of use, the power supplies have sepa- rate digital displays for volt- age and current readout, a CC-set button for setting the current level of the sup- ply without having to short the output, and mode-in- dicator LED's to show whether the supply is in CV or CC mode. The HP E3610A and HP 3611 A each cost $300 — Hewlett-Packard Company, 150 Green Pond Road, Rockaway, NJ 07866: Phone: 1-800-538-8787. THERMAL-PRINTER CONTROLLER. De- signed for anyone who needs a small-printing for- mat, Computer Advice has introduced a 5- volt, 2Vi- inch-format high-speed thermal-printer controller. The device interfaces with the Seiko STP 211-192 Thermal Printhead and op- erates on five volts at less than one amp with serial in- terface active. The control- ler prints bi-directionally and includes either vertical or horizontal formats. The co ntrol ler can be customized for each indi- vidual's use. In certain ap- plications, it is capable oF 250 words per minute. The complete package consists of an 80C31 pro- cessor board, the printer controller board, a DB-25 serial-interface connector, and one package of ther- mal fanfold paper The ther- mal printer is sold uncased for more versatility, and can be purchased with options such as a wall-mounted power supply and the Seiko Thermal Printhead. The thermal printer con- troller costs $145. — Com- puter Advice, 515 Calle San Pablo, Camarillo, CA 93012. PIEZO SOUNDER. A high-output piezo sounder From International Compo- nents Corporation is in- tended for use in auto- motive, marine, and other applications where there might be exposure to high temperatures. The model BRP-4629P9-CS has an operating range of —40° to CIRCLE 21 ON FREE INFORMATION CARD CIRCLE 22 ON FREE INFORMATION CARD + 120°C. It provides a con- tinuous tone with trigger and its sound output rate at one meter is 2.8-kHzat 105 dB, for a clear warning sound, Its resonant fre- quency is 2500 ±500 Hz, and its rated voltage is 9VDC. The model BRP-4629P9- CS is priced starting at $3.60 in production quan- tities. — International Components Corpo- ration. 105 Maxess Road, Melville. NY 11747; Phone: 516-293-1500. 26 12-FUNCTION DIGITAL MULTIMETERS. The combination of large LCD readout, annunciators for all available ranges, and the number of available ranges make the DM25XL and DM27XL digital multi- meters easy to use for most jobs, eliminating the need to carry around a case full of test instru- ments for different jobs. The two meters, from Beckman Industrial Corpo- ration, provide 12 functions in one unit, and the annun- ciators lessen the chance of using the wrong range. Both units are S'/a-digit, CIRCLE 23 ON FREE INFORMATION CARD 0.8% -accuracy DMM's that feature 37 ranges, an audible continuity beeper, diode test, logic functions, and transistor hFE mea- surements. To conserve battery life, auto-off is also standard. The DM27XL adds to those functions a go/no-go test on LED's and includes the ability to measure frequency to 20 MHz, which is needed for servicing both telecom- munications and computer equipment. Both models include a built-in TTL logic probe that detects 20-ns pulses (2.4 volts high and 0.7 volts low). The two DMM's each have seven resistance ranges to 2000 megohms, five capacitance ranges to 20 (jlF. AC and DC current measurement to 10 amps, five VAC and five VDC ranges, and the ability to test diodes and measure transistor gain. The input impedance is 10 megohms. The DM25XL and the DM27XL digital multi- meters have suggested re- tail prices of $109 and $129, respectively. — Beckman Industrial Corporation. 3883 Ruffin Road, San Diego. CA 92123-1898: Phone: 619-495-3200. PROTOTYPING SYS- TEM. Providing a complete system for the develop- ment of embedded control applications, the R-535 prototyping board with R- Ware from Rigel Corpora- tion features efficient soft- ware and on- board pro- totyping components in a single integrated unit that's designed to communicate with a PC acting as host. The R-535 uses the 80535 microcontroller, an en- hanced version of the pop- ular Intel 8032 controller, and can be used to develop programs for the entire 8031 family of micro- controllers. The on-board ROM- circle 24 ON FREE INFORMATION CARD based software includes an operating system, a monitor system, EPROM burner software, and user- accessible system-calls for control and communication support. The host-based software is a menu-driven integrated environment with an editor, assembler, debugger, and PC-to- board communications. The hardware consists of pushbuttons, dip switch- HANDS-ON TECHNICAL SEMINARS FOR PROFESSIONALS "Servicing the Video Laser Disc Player" - El A I CEG "Hot-Air Soldering Techniques" - Thomson Consumer Electronics "Advanced Digital Circuitry - Digital TV" - Toshiba America, Inc. "Troubleshooting Tough VCR Mechanical and Electronic Problems" - Tentel Corp. and Sen core, Inc. "Microprocessor Controls - Troubleshooting Techniques Using the Mitsubishi Wide-Screen Simulator" - Mitsubishi Electronics America Courses FREE when registered at the National Professional Electronics Convention August 5-11, 1991; Nugget Resort, Reno NV. Full $230 Registration (at door) includes: • Alt Technical Training Seminars (limited seating) • Alt Management and Business Seminars • Continuing Education units for all seminars attended • Two Day Trade Show • Head-to-head Meetings with Manufacturers' National Service Managers *AII Sponsored Meals and Functions • NESDA I ISCET Association Meetings • Price discounts available for pre-registration Sponsored by the National Electronic Sales & Service Dealers Association and the international Society of Certified Electronics Technicians For more information, contact NPEC '91 2708 W. Berry St., Fort Worth, TX 76109-2356 (817) 921-9061; fax (817) 921-3741 c 5. CD CD 27 CABLE ■ TV SIGNAL REMOVERS -FOR ELIMINATION OF SEVERE INTERFERENCE •FOR "CENSORING' OF ADULT BROADCASTS ■ ATTENUATION - 45 dB TYPICAL ■ BANDWIDTH - 4 MHl AT 5 dB POINTS ■ INSERTION LOSS - 2 dB MODEL TUNING RANGE CHANNELS PAUBAND PH»CE SHIPPING 23K S0-6E MHz 2.3 [o* 6 matir him] 50-300 MHz 130 NO SHIPPING or CO.D. CHARGES Jct',1 S$-loa MHz 4,5.6 tor iniFMl 50-300 MHl 130 1417 120-144 MHl 1414)15(8) 16 [CI 17(0] 50-400 MH i 130 1S22 144-174 MHz U(E) 19(F) 20(G) 21 (H ,2Z(I| 50400 Mm $30 713 174116 MHl 7.8.9.1011 13.13 5C u; Mil; S30 3 for $75 - 1 for $200 - mix or match CALL TOLL FREE FOR COD. OR SEND CHECK TOORDER FASTDELIVERY 30 DAY MONEYBACK GUARANTEE (3 FILTE RLIM(T) Star Circuits P. 0. Box 94917 Las Vegas, NV 89193-4917 1-800-433-6319 AtfiC! o z o rr r- o LU o Q < 28 An ETCHED circuit board from a Printed PAGE in just 3 flours The ER-4 PHOTO ETCH KIT gives you the tools, materials and chemicals to make your own printed circuit boards. The patented Pos-Neg"" process copies artwork from magazines like this one without damaging trie page Use the circuit patterns, tapes and drafting film to make your own 1X artwork. Or try the Direct Etch" system (also included), to make single circuit boards without artwork. The ER-4 is stocked by many electronic parts distributors, or order direct, postpaid, ER-4 PHOTO ETCH K1T(NJ and CA residents add sales tax) . . .538.00 DATAK S COMPLETE CATALOG lists hundreds of printed circuit products and art patterns Also contains dry transfer lettersheetsand electronic title sets for professional looking control panels WRITE FOR IT NOW! DATAK Corporation • 55 Freeport Blvd, Unit 23 • Sparks, NV 89431 CIRCLE 176 ON FREE INFORMATION CARD es. LED's. numerical dis- plays, and potentiometers for emulating control-ap- plication inputs and out- puts. There are two sol- derless breadboard termi- nal strips, one connected to the prototyping compo- nents and the other to the microcontroller ports and control lines — plus a large solderless breadboard. That setup provides flex- ibility for connecting pro- totyping components to the microcontroller lines and for developing and de- bugging user-designed analog and digital applica- tion circuits. The R-535/R-Ware package — including a 100- plus-page users guide with schematics, board layout, and control experiments with software examples — is available as a kit for $395 or assembled and tested for $495.— Rigel Corpo- ration. P.O. Box 90040, Gainesville. FL 32607. DIGITAL STORAGE OS- CILLOSCOPE. Featured functions in the Protek Model P2840 DSO are 20- megasample per second CMs/s) sampling and "Vu- Write" cursor CRT read- outs. In addition, the 40- MHz real-time DSO deliv- ^^P \m •J r v * * --■, ■ :.« «- ».! 1. .-■] 1 HP ^^B 1 B^H ■ CIRCLE 25 ON FREE INFORMATION CARD ers a vertical resolution of 256 dots, a horizontal reso- lution of 1024 dots, indicat- ing memory of 2048 words, reference memory with storage of up to four sig- nals, and an 8-MHz effec- tive storage frequency. Pre/post trigger is at 25% and 75%. and there are a variety of rear panel inter- connects for extended use. Key analog functions include dual time base, push-button switch selec- tion with vertical and hori- zontal mode "select" for fast setup and readout, and an easy- to-read front-panel layout. In addition, the P2840 offers a memory function and cursor read- outs to indicate time, am- plitude, frequency, duty cycle, and phase shift. The P2840 digital stor- age oscilloscope costs $1630.— Protek. P.O. Box 59, Norwood, NJ 07648; Phone: 201-767-7242: Fax: 201-767-7343. PORTABLE AUDIO GENERATOR. Designed for the audio professional, Forward Innovations' CIRCLE 26 ON FREE INFORMATION CARD PAG-I hand-held portable audio generator provides a versatile means for check- ing sound systems. The generator has a variable output up to 1 volt and is DC decoupled so that it can be used to measure im- pedance. It can also be used to check capacitance and inductance. The PAG-I boasts a THD of less than 0.03% and it sweeps from 18 Hz to 22.5 kHz in three continuous overlapping ranges. The dial is marked in Vb-octave segments for easy check out. It runs on a 9-voit battery and is pro- tected to 50 volts DC or 30 volts AC. The PAG-1 portable au- dio generator is $139. — Forward Innovations, P.O. Box 9429. Santa Rosa, CA 95405 R-E NEW LIT Use The Free Information Card for fast response. RF DEVICE DATA: VOL- UMES I and II; from Motorola, Inc., Literature distribution Center, P.O. Box 20924, Phoenix, AZ 85063; Phone: 602-994-6561. This two-volume set rep- resents the latest and most CIRCLE 40 ON FREE INFORMATION CARD complete listing of stan- dard products offered by the RF Products Division of Motorola Semiconductor. The set lists complete data for all RF products in Motorola's portfolio, in- cluding power FET's. power bipolar, small-signal, and modules. Data sheets on 84 new products are in- cluded, as well as addi- tional items in the applica- tions section. HOME WORKS BY HEATHKIT; from Heath Company, Department 350-055, Benton Harbor, Ml 49022; Phone: 1-800-44-HEATH; free. The cover story of Heath kit's Spring 1991 cat- alog is an 8-bit micro- processor trainer in kit form. The practical learning tool, used to perform ex- periments for Heath courses, is specially de- signed to improve under- standing of 8-bit micro- processor operation, pro- gramming, and applica- tions. The trainer can be used with many of the CIRCLE 39 ON FREE INFORMATION CARD latest 8- bi t m icro- processors simply by switching plug-in modules. An RS-232 interface lets the trainer be used with a terminal, and a built-in sonic logic probe lets the user check high, low, or pulse signals both visually and audibly. The 40-page catalog also introduces four new home-study video courses on component recognition, soldering, digital tech- niques, and micro- processors. The video courses are condensed, home-study versions of VHS tapes formerly used in university classrooms. Also featured are courses in basic and advanced elec- tronics, laser technology, electro -optics, surface mount technology, and am- ateur radio; and a variety of innovative educational kits for both beginning and ex- perienced kit builders. THERE ARE NO ELEC- TRONS: ELECTRONICS FOR EARTHLINGS; by Kenn Amdahl. Clear- water Publishing Com- pany, Inc., Scenic Heights Professional Building, P.O. Box 1153, Arvada, CO 80001-1153; Phone: 303-42206725; $12.95. We'll assume, since you're reading Radio- Electronics, that you un- derstand electricity. (But then, we thought we did, too, until we began reading this bookJ A bizarre cross between Grimms's Fairy Tale s and Richard Brautigan's Trout Fishing in America, with a hefty dose of 1960s imagery and slang thrown in, the book takes a totally irreverent look at some pretty serious stuff. If your career revolves around the understanding of electricity, and you have years of higher education in that field, you might have little patience for this book. But if you believe that one prerequisite to a happy, healthy life is the ability to laugh at yourself, read it. And if any of you have ever tried to explain electricity to spouses, children, friends, or parents, only to see their eyes glaze over after a minute or two. this book could do the trick. CIRCLE 38 ON FREE INFORMATION CARD Although the author claims to base his work on the dual premises that "No one really understands electricity" and "No one wants to admit it." he does a commendable job of fur- thering the general under- standing of electricity in a unique style. And, although he warns that analogies ("electricity is like water flowing through a pipe") are imperfect models that can be dangerous when taken as representations of reality, he has created some of the most unusual analogies we've ever come across. Not only is there no chance of these models being taken as reality, there's also little chance that anyone who reads them will ever forget them. Somehow, between the laughs, a real understand- ing of electricity unob- trusively takes hold. CASE CATALOG; from Jensen Tools, Inc., 7815 South 46th Street, Phoe- nix, AZ 85044; Phone: 602-968-6231; free. CIRCLE 37 ON FREE INFORMATION CARD The 32 illustrated pages in this catalog describe transport products for electronic engineers and field-service technicians. Included are hard- and soft- sided, rugged-duty, and at- tache-style cases in all sizes for carrying tools. PC boards, test instruments, and other electronic ser- vice equipment. The color catalog also features airline shipping containers, and describes Jensen's custom-case and custom- tool-kit design services. c CO to 29 CD O •z. o DC F o LU _J LU 6 < EC 30' (1) Talking Multimeter. Timesaving speech output! Press a button on the probe and this meter calls out the reading in clear English while displaying it. Features Include full autoranging. liquid crystal display with low-battery and over-range indicators, continuity beeper, diode-check mode. #22-164 99.95 (2) NEW! Building Power Supplies. Easy-to- understand, 96-page bock explains linear and switching supplies. Includes complete plans for building five useful supplies with Radio Shack parts. #276-5025, 4.95 (3) Mini Audio Amplifier. Great for computer voice/music synthesis, signal tracing and more. Has a built-in speaker, Vn" headphone jack, Vs" input jack and volume control. #277-1008 11.95 (4) Digital Logic Probe. LEDs and tone outputs reveal logic states instantly. It's the fast way to check operation and pinpoint problems in all types of digital circuits. #22-303 16.95 I ■ U\ Jll - j '- i ^ '• t 11 Parts Special-Order Hotline. Your local Radio Shack store stocks over 1000 popular electronic compo- nents. Plus, we can special-order over 10,000 items from our ware- house — linear and digital ICs, tran- sistors and diodes, vacuum tubes. Crystals, phono cartridges and styli. even SAMS 1 service manuals. Your order is sent directly to your Radio Shack store and we notify you when it arrives. Delivery time for most items is one week and there are no postage charges or minimum order requirements. (1) Shielded RS-232 Jumper Box. Top-quality inline D-sub 25 adapter. Wire the included jumper wires and board to suit your need. #276-1403 9.95 (2) RS-232 Tester. Dual-color LEDs monitor seven dataJcontrol lines to help you spot problems quickly. D-sub 25. Connects inline, #276-1401 14.95 (3) Grounded -Tip Soldering Iron. 15W. #64-2051 7.4S (4) Vacuum-Type Desoldering Tool. #64-2120 6.95 (5) Locking Forceps. 6" long. Stainless. #64-1866 4. 95 (6) Rosin Soldering Paste Flux. #64-021 1.79 (7) Lead- Free Solder. 0.25 oz. #64-025 1.99 Over 100 soldering items and tools for electronics work are in stock at Radio Shack! (8) IDA Microwave Oven Fuses. #270-1256 Pkg. of 2/1.29 (9) 2-Amp Fast-Acting Fuses. #270-1275 Pkg. of 3/79C (10) 5-Amp "Blade" Car Fuses. #270-1205 Pkg. of 2/89C Big selection of fuses, holders and accessories in stock! Computer/Business Machine AC Power Cords. 6 feet long. (11) Extension. #278-1259 4.99 (12) With Space-Saving 90° CEE Connector. #278-1260 5.99 (13> With Straight CEE Connec- tor. #278-1257 3,99 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 stores and dealers. Radio Shack is a division o1 Tandy Corporation CIRCLE 78 ON FREE INFORMATION CARD 15) DO M DEI (1) Voltage Regulator ICs. Fea- ture built-in overload protection and thermal shutdown. Maximum input: 3SVDC. 7805. 5V, #276-1770 1.19 7812. 12V. #276-1771 1.19 (2) Low-Voltage Motor. Just the thing for science projects, robotics and solar power demos. Operates Vfe to 3VDC. About Vh" long. #273-223 99S (3) Htgh-Speed 12VDC Motor. Up to 15,200 RPM, no load. About 2" long #273-255 2.99 (4) "Ding. Dong" Chime, This IC and mini-speaker combo is ideal for a customer- en try alert or doorbell. Produces 80 dB sound pressure at 12 VDC. Operates 6 to 18 VDC. #273-071 8.99 (5) Surface-Mount Resistors. 200-piece assortment of 15 popular values. Rated Vs watt. 5%. #271-313 Set 4.99 Radio Shack Has 20 different project enclosures in stock! (6) Metal Project Cabinet. An at- tractive, easy-to-drill housing at a low price. 3x 5V* x 5 7 /b" #270-253 6.79 (7) Project Labels. Four sheets of rub-on letters, numerals and cali- brations. #270-201 2.99 (8) Power Supply Case. Vented 2Va x 4* x 3'/«" molded case. #270-287 3.99 (9) to 15 DC Voltmeter. Panel- mount. #270-1754 7.95 (10) Box/Board Combo. Molded enclosure plus predrilled 2x3Ve" board, labels and more. #270-291 4.99 (11) Eight-Position Phono Jack Board, #274-370 1.39 (12) 1:1 Audio Transformer. Z; 600-9000. #273-1374 3.59 (13) Three-Pin XLR Mike Plug. Metal body. #274-010 2.99 (14) Three- Pin XLR Mike Inline Socket. #274-011 2.99 (15) Three-Pin XLR Mike Panel Socket. #274-013 3.69 .Radie/haek America's technology store IF YOU'RE INTERESTED IN MEDICAL ELECTRONICS. OR just concerned about your family's health, then you should build the Radio-Electronics electrocar- diograph. The electrocardiograms (ECG s or EKG's) it will produce can be analyzed by yourself or your doctor. We are not suggesting that you practice medi- cine using this device, but you should find it interest- ing and educational in monitoring your health. You will see some of the unique techniques used in medical electronics and you may be surprised to see how similar medical electronic equipment is to most other types of electronic equipment. The electrocardiograph that we will build pro- duces ECG's that are essentially identical to those produced by commercial machines costing $10,000 dollars or more. In order to keep our cost to a minimum we use a standard PC as an operator interface and output device. That way you can print out a hard copy of your ECG or just display it on your monitor. Biological theory In order to understand the electronic operation of an electrocardiograph, we need to understand some basic biological principles. As shown in Fig. 1, the heart consists of four chambers which are organized as two pumps — the so-called right and left heart. The right heart collects the blood return- ing from the body and pumps it to the lungs, while the left heart collects blood from the lungs and pumps it to the body. Each pump has two parts: the upper chamber known as the atrium and the lower chamber known as the ventricle. The atrium collects blood between cycles and at the appropriate time con- tracts, filling the lower ventricles. The ventricles then contract and pump blood to the lungs or body. The heart is controlled by a pulse generator, known as the pacemaker, located in the right atrium, which initiates cardiac action. Il Is analo- gous to the clock in a digital system. The pulse it generates is first sent to both atrium which causes them to contract, filling the ventricles. After a delay of approximately 150 milliseconds, the ventricles are then triggered by the same pulse, which causes them to contract. As in a digital system, the timing relationships are quite important and much of the disease associated with the heart is related to tim- ing defects. Figure 2 shows a typical signal as seen on an ECG. The first pulse, called the "P" wave, is gener- ated by the pacemaker. The next pulse, called the "QRS complex," represents the electrical signal generated by the ventricles contracting. The "T wave" which follows the QRS complex is generated as the muscles of the ventricles relax, or repolarize. A standard ECG consist of 12 channels: each channel "looks" at the heart from a different elec- trical axis. The different "views" allow us to inter- pret the activity of different parts of the heart. The timing relationships between different compo- nents of the heart will identify defects in the con- duction pathways. How ECG's are used In patients with high blood pressure, the left ventricle will become quite large due to its in- ELECTROCARDIOGRAPH Dala&Joeto. Inc. -AJL-Oat W3± r -frt \Keep an eye on your health and learn about medical electronics with the Radio-Electronics electrocardiograph. m WARNING!! This article deals with and involves subject matter and the use of materials and substances that may be hazardous to health and life. Do not attempt to implement or use the information contained herein un- less you are experienced and skilled with respect to such subject matter, materials and substances. Furthermore, the information contained in this article is being provided solely to readers for educational pur- poses. Nothing contained herein suggests that the monitoring system described herein can be or should be used by the assembler or anyone else in place of or as an adjunct to professional medical treatment or advice. Neither the publisher nor the author make any represen- tations as for the completeness or the accuracy of the information contained herein and disclaim any liability for damages or injuries, whether caused by or arising from the lack of completeness, inaccuracies of the infor- mation, misinterpretations of the directions, misapplica- tion of the information or otherwise. 31 BODY « o z c cr F o hi _i UJ 6 Q < DC LUNGS PACEMAKER BODY FIG. 1— THE HEART CONSISTS OF FOUR CHAMBERS which are organized as two pumps, known as the right and left heart. The right heart collects the blood returning from the body and pumps it to the lungs, while the left heart collects blood from the lungs and pumps it to the body. TABLE 1—1/0 PORT ADDRESS FUNCTIONS Port Address Control Pulse Function 52 53 54 55 Generates Clock for Multiplexer Sequencer Generates Clear for Multiplexer Sequencer Latches ECG Control Signal Byte in IC1 6 Latches Lead Offset Data in IC17 creased work load. That is seen as a significant increase in the amplitude of the QRS complex. Treatment of the high blood pres- sure will allow the left ventricle to return to normal size, which sig- nificantly decreases the chance of a heart attack. Since the amplitude of the elec- trical signals in the heart are a function of chemicals in the body, it is possible to predict ab- normalities. For example, an ele- vated potassium level will pro- duce a tall peaked T wave. If a portion of the ventricle is damaged, a so-called "Q wave" is formed which is simply a nega- tive-going QRS complex. The lo- cation of the damage can be determined by noting which leads contain the Q wave. That's how a doctor can tell where you have had a heart attack. Most normal individuals pro- duce an extra, or irregular heart beat every now and then, which may occur in the top or bottom of the heart. It is a condition known as arrythymias. The irregular beats can be quite dangerous if they occur frequently or if they occur during certain intervals in the normal cardiac cycle. Many researchers believe that the most common cause of death in males is due to irregular beats occur- ring at a time such that they "scramble" the normal electrical timing in the heart — the situa- tion is known as fibrillation. Special ECG systems, known as Holier monitors, can detect these irregular beats. They are simply ECG's with one or more channels that store each of the 80,000 or so beats in one day. The data from the Holter is then fed into a computer which analyzes it for arrythymias. Similar P-R SEGMENT : S-T SEGMENT p.. V. !.'/.". r PR INTERVAL!- QRS COMPLEX | Q-T INTERVAL H FIG. 2— A TYPICAL SIGNAL as seen on an ECG. The first pulse, called the "P" wave, is generated by the pacemaker. The next pulse, called the "QRS complex," repre- sents the electrical signal generated by the ventricles contracting. The "T wave" which follows the QRS complex is gener- ated as the muscles of the ventricles relax, or repolarize. FIG. 3— TEN LEADS ARE CONNECTED to the patient in a 12-channel system: they are right arm, left arm, left leg, and 6 chest leads called the V leads. The right leg is used as a ground and as an input to re- duce system noise. monitoring equipment is used in ambulances and intensive care units for instantaneous analysis of irregular beats. Often this analysis is performed automat- ically by arrythymia detectors. Another area of particular in- terest in ECG's is the "ST seg- ment." That is the area between the QRS and the T wave. It is very predictive of obstructed arteries before any damage occurs to the heart. Obstruction of an artery will result in a depressed ST seg- ment of the ECG— it will fall be- low the base line in the affected leads. The exercise cardiogram, or stress test, looks primarily at the ST portion of the ECG to pre- dict if any of the hearts arteries are becoming clogged. It is possible to become quite 32 9 INPUT LEADS > INPUT BUFFERS 9 INPUT LEADS MULTIPLEXER TO RIGHT FOOT BATTERIES AND BATTERY CONTROL WILSON ELECTRODE BATTERY ON WILSON ELECTRODE REFERENCE DIFFERENTIAL AMPLIFIER OPTICAL INTERFACE AND AMPLIFIER INTERFACE ELECTRONICS OPTICALLY ISOLATED NOT ISOLATED I FILTER FILTERED ECG DATA ANALOG TO DIGITAL CONVERTER J> DATA AND CONTROL CONTROLLER <=> MEMORY PERSONAL COMPUTER RS-232 PRINTER FIG. 4— BLOCK DIAGRAM OF THE COMPLETE ECG SYSTEM. The system logically divides into the front-end electronics and the controller. Data communication between the analog and digital portion of the ECG is accomplished through optical isolators, which helps keep the patient isolated. All resistors are Vi-watt, 5%, unless otherwise noted. R1— 10 ohms R2. R7-R1 0—10,000 ohms R3-R6, R15, R16— 1000 ohms R11— 7500 Ohms R12— 24,000 ohms R13— 30,000 ohms R14— 10,000 ohms x 8, SIP Capacitors C1-C22, C25, C26, C28. C29. C33, C34, C42— 0.47 ^.F. ceramic disk C23, C24 — 22 pF, ceramic disk C27. C30— 0.001 nF, metal film C31— 220 pF. ceramic disk C32— 10 p.F, 10 volts, electrolytic C35, C38, C39,— 10 jaF, 10 volts, tantalum C36. C37. C40, C41— 1 jj.F, 10 volts, tantalum Semiconductors IC1— Z80 CPU 1C2-IC5, IC12— 74HC245 bus transceiver IC6, IC8— Altera EP320 PAL IC7— Altera EP600 PAL IC9— 27C256 EPROM IC10, IC1 1—55257 static RAM IC13— 74HC688 equality comparator PARTS LIST— CONTROLLER IC14— 74HC138 1-of-8 decoder IC15 — 82C52 UART IC16, IC17— 74HC573 octal latch IC18— 74HC74 dual D flip-flop IC19— MC145406 RS232 transceiver IC20— AD0829 AD converter IC21. IC22— DAC0830 D/A converter IC23. IC24— NE5532A op-amp IC25— 74HC14 hex Schmitt inverter IC26— 74HC00 quad NAND gate IC27— PS2501A-2 optoisolator IC28. IC31— not used IC29— ICL7660 DC-DC converter IC30 — 78L06AC voltage regulator IC32— 7805 voltage regulator D1-D4— 1N914 diode D5 — 5.1 -volt Zener diode D6 — 6-volt Zener diode Q1— IRFZ10 N-channel MOSFET Other components XTAL1— 2.4576 MHz crystal XTAL2— 8.00 MHz oscillator S1— SPDT momentary contact switch S01— DB25 connector Note: The following items are available from DataBlocks, Inc., Glenwood, GA 30428, (912)568-7101. • Design package including sche- matics, assembly instructions, and checkout- and plot-software design specifications (ECG-DP): $27.00. • Front-end PC board, controller PC board, and design package from above (ECG-PC): S74.00. • Complete kit of parts, including both PC boards, IC's, sockets, pas- sive components, design package, ECG software, and checkout soft- ware (ECG-KIT): $289.00. • Lead kit consisting of 50 feet of 29-gauge shielded cable, 10 alligator clips, heat-shrink tubing, and in- structions (ECG-LD); $53.00. • EPROM containing ECG soft- ware, ECG resident portion of check- out software (ECG-PROG); $45.00. • Set of four programmed PAL's (ECG-PAL): S67.00. • Case as shown with mounting hardware (ECG-CASE): $29.00 * Package of 100 self-adhesive elec- trodes (ECG-EL): $20.00. Please include $5.00 shipping and handling for design package and electrodes, $10.00 shipping and han- dling for all other products. Georgia residents must add sales tax. c 5 33 FPOJ* ATOrfT- Aft* ,c n r[ — TT ^f> ra&* left *»" ■O FTOh tEFT lID -o .■SF.. M^-ir ■o "™0 1 """T,.™ • iH*]- ■o- Wl3 O 1 „~i "a F Vs^" T T * 1*^ ■o — Sr-i — pi MMD *H Bat .j. 6/4 LH34* tOK ^ MEJoFT Ql7 ■■■■■. ,Slh •Kit* L TO HI9HT LCQ 0"™ _ — ^ — i — r~i — B*lt1 BEF NC HC *4C HE ^ 4- *IrJFiJ 1- rBthlM J- ATI Ml -I :>■:■■■ §- w -I**UT ■ _ I *Fh •#*!« KM ■ ! HULL "TO MJU. ' ■ TO MU.L ■ ■AIM DP ,-*si r* : B30 iP3* PHI lOBft jVJ/4 LM 1/4 LH3*I ,"%; J S3 4-7K , . .Hi'' r^^w Hftc * - xa 1 ■**- X3 ) n«en T i*T -ft' :0 HO Ji XI K| 1 ■ 'ill* Eeasi_»4 6 FIG. 5— THE FRONT-END ELECTRONICS lakes in the signals from the 9 input leads 2 located on the patient. The small signal from each of the leads is fed into the quad op £ amps IC1, IC2, and IC3-a. 34 |c3N [CJg _[eSfl JC37 Jfli JcSB Jf4 ^f ~[0 .47 ~T5 47 *T7> *7 "To 47 "Tfl . -47 "To . 47 Ha 1 — PH — f — 1 — 1 — 1 |C*i Jc+a _|c+a Jj:4* _JC4H Jt4H _|c*t "To . 47 "To . -47 "To 47 "To . 47 "Tfl . 47 "TS 47 Ho . 47 J 1 II 1 J I c 1 35 w o z o rr \- o LU 6 < EC PARTS LIST— FRONT-END All resistors are Vi-watt, 5%, unless otherwise noted. R1-R9, R1 3— 20,000 ohms R10, R24. R60, R63— 30,000 ohms R1 1—1800 ohms R12, R25, R44— 10,000 ohms, potentiometer R14, R18, R26— 4700 ohms R15. R1 7— 19,200 ohms R16— 39.2 ohms, 1% R1 9— 200,000 Ohms R20-R22. R41— 100,000 ohms R23— 1500 ohms R27— 910 ohms R28, R39, R40, R55, R59, R62, R67— 10.000 ohms R29. R46. R48— 15,000 ohms R30— 200,000 ohms, potentiometer R31, R36— 680.000 ohms, 1% R32— 500,000 ohms R33— 68 ohms R34— 15.000 ohms, potentiometer R35— 100 ohms R37, R38, R43, R61— 170 ohms R42. R64— 1000 ohms R45. R51— 680.000 ohms R47— 5000 ohms, potentiometer R49— 330.000 ohms R50, R58— 2200 ohms R52, R56— 1.5 megohm R53— 150 ohms R54— 150,000 ohms R57— 12,200 Ohms R65— 3300 ohms R66— 1000 ohms, potentiometer Capacitors C1-C10— 220 pR 1000 volts, ceramic disk C11, C19, C20— 10 tiF, tantalum C12, C13— not used C14, C23, C24 — 1 (j,R ceramic C15 — 0,001 |j.F, metal film C16 — 39 pF, ceramic disk C17— 120 pF, ceramic disk C18 — 0.01 |iF, metal film C21, C22, C31-C47— 0.47 ^F, ceramic disk C25-C30— 1 |xF T tantalum C48, C49— 47 jiF. 16 volts, electrolytic Semiconductors IC1-IC3, IC9, IC10— LM348 op-amp IC4 — AD625 instrumentation amplifier IC5— TL431C precision voltage reference 1C6 — 4051 analog switch IC7— 4052 analog switch IC8— Altera EP320 PAL IC14, IC15— OP18012 optoisolator IC16, IC17— PS2501A optoisolator IC18, IC20— 78L06AC voltage regulator IC19— 78L05AC voltage regulator D1-D20— 1N914 diode Q1, Q2— IRFD123 N-channel HEXFET Other components B1-B3— 9-volt battery skilled at reading the ECG with- out being a medical expert, and there are a number of texts on the subject that you will find interest- ing. In particular, try Duben's Rapid Interpretation of EKG's — with it, you can become fairly knowledgeable of ECG s in a mat- ter of a few hours. A more soph is- CLK CLEAR CO nnnnnnnnnnnn — — 1 1— | r 1 1 1 1 1 t — 1 C1 1 C2 C3 CTLA 1 1 1 | CTLB 1 1 1 FIG. 6— PAL IC8 SEQUENCES THE MULTIPLEXER ADDRESS LINES so that each input signal is sequentially passed to the multiplexer output for processing. This timing diagram shows the relationships between the PAL's input, output, and control signals. ticated text written by Marriott is entitled Practical Electrocar- diography, Sources for these texts are listed in the Sources Box of this article. Biological interface The patient is connected to the electrocardiogram via 3—12 leads in a typical system. The 3-lead systems are used when only the cardiac rhythm is to be studied — in an ambulance, monitoring an athlete, in an intensive care unit, etc. If a detailed analysis of the heart is required, a 12-channel system is normally used. The sys- tem that we will build will gener- ate a full 12-channel read out. Ten leads are connected to the patient in a 12-channel system: they are right arm, left arm, left leg, and 6 chest leads called the V leads (see Fig. 3). The right leg is used as a ground and as an input to reduce system noise. Youmightwellaskhowwegeta 12-channel system only using 9 active leads. That is accom- plished by combining different leads together. For example, lead "aVR" is equal to the voltage at the right arm minus the sum of the voltages at the left leg and left arm. Table 1 shows how the sig- nals are combined. Our system will collect the data in each lead, digitize them, and then digitally combine the signals within the host computer. More on this later. A typical QRS will have a peak amplitude of 1 to 2 millivolts. That may mix with noise (60-Hz hum, for example) with much higher amplitudes. The problem. then, is to distinguish the car- diac signal from the unwanted signal. That is accomplished in biological instrumentation in much the same way as industrial instrumentation; by the use of differential amplifiers. These cir- cuits can attenuate the un- wanted signal by 100 dB or more. The electrode that connects the ECG to the patient must make a low-impedance connection be- tween the system and the pa- tient's skin. That is typically accomplished by the use of dis- posable silver electrodes, which we will use in our system. The electrodes are made of a silver- chloride gel that provides low im- pedance and a minimum amount of electrical noise with the skin. One of the fundamental princi- ples that medicine is based on is from the Hypocrites Oath, "do no harm," That means under no cir- cumstances should there ever be a possibility of doing any harm using medical instrumentation. In the case of an ECG , the main concern would be the shock po- tential through the electrodes. In our system we optically isolate the patient from the rest of the electronics. Therefore, even if all the safeguards in the computer's power supply were to fail, the pa- tient would still be protected from shock. One other concern is to prevent the patient from doing harm to our equipment. In our ECG we provide a resistor-diode network on each lead which prevents a high voltage from entering the 36 ADDRESS FROM PAL CONTROL FROM PAL MULTIPLEXER STATE IC6 IN -OUT IC7 IN - OUT C3 C2 Cl CO CTLB CTLA XO -X XO - X YO - Y 1 XI -X XO - X YO - Y 1 X2 -X XO -X YO -Y 1 1 X3 -X XO -X YO -Y 1 X4 -X XO -X YO-Y 1 1 X5-X XO -. X YO - Y 1 1 X6 -X XO ■* X YO - Y 1 1 1 X7 -X XO -X YO ■ • Y 1 1 z X1 -. X Y1 - Y 1 1 1 z X2 - X Y2 ■* Y 1 1 1 1 z X3 - X Y3 - Y NOTE: Z = OUTPUT IN HIGH IMPEDANCE STATE FIG. 7— MULTIPLEXER TRUTH TABLE shows how the signals from the PAL are used to control the sequencing of the input signals to the input of the instrumentation amplifier. front-end amplifiers. An example where this might be significant would be in the case where a pa- tient is "shocked," or defibril- lated. after a cardiac arrest. In that case up to 400 volts could appear across the electrodes coming from the patient. Now that we have a basic un- derstanding of the underlying bi- ological principles associated with the E.CG , let's look at some of the technical details of the ma- chine which we will construct. Then let's build one! System Theory of Operation A block diagram of the com- plete ECG system is shown in Fig. 4. The system can be divided into the front-end electronics and the controller. The analog portion attaches to the patient with 10 lead wires: 9 input leads, and 1 output, or reference lead. The analog portion of the ECG is powered by two 9-volt batteries to isolate the patient from any po- tentially dangerous power cir- cuitry. In addition, data com- munication between the analog and digital portion of the ECG is accomplished through optical isolators, which also helps keep the patient isolated. The controller section of the system contains a Z-80 based computer with 32K of RAM and 32K of EPROM. The controller section of the ECG also contains the analog-to-digital (A/D) con- version circuitry to convert the patient's analog ECG signals to the digital data required for com- puter processing. In addition, this section generates control signals to sequence the A/D con- version, compensate for input channel offset, and control the input-lead multiplexer. Notice that we have included a personal computer and printer in the diagram. Although not a part of this construction article, they are an integral part of the system since they provide the display for the ECG traces. Front-end electronics As previously discussed, the 12-trace ECG is derived from 9 input leads located on the pa- tient. The small [approximately 1 millivolt) signal from each of the leads is fed into the quad op- amps IC1. IC2, and IC3-a. as shown in the schematic of Fig. 5. The op-amps are configured as non-inverting, unity-gain ampli- fiers. They provide a very high in- put impedance that prevents the signals from the body electrodes from being loaded down. Notice also that the input to each ampli- fier circuit is shunted to ground by a 220-pF capacitor (C1-C10) and two diodes (Dl— D20) in par- allel. Those components are used to protect the input of the ampli- fier from the high voltages pres- ent during cardiac defibrillation, and to provide patient protection in the unlikely event that high voltage should feed back through the amplifier. The output of the three limb leads from ICl-a. ICl-b and ICl-c are summed into op-amp 1C3-D, inverted, and fed back to the pa- tient through the 10th lead which is attached to the patient's right leg. The composite signal from the three limb leads is called the Wilson Electrode. The Wilson Electrode signal significanUy re- duces the common-mode noise in the system, since unwanted signals common to the three limb leads are fed back to the patient 180 degrees out of phase with the original noise. The signal from the Wilson Electrode is again in- verted in op-amp IC3-c and routed to the multiplexer to even- tually form the reference against which the nine input signals are compared. The multiplexer is made up of two integrated circuits, IC6 and IC7. in conjunction with the mul- tiplexer-controller IC8. Analog- switch IC6 has 8 inputs (X0-X7). One of the eight inputs is con- nected through a very-low-im- pedance path to the output (X) according to the 3-bit address ap- pearing on the control inputs CO— C2. For example. XO is con- nected to X when the control ad- dress is 000. XI is connected to the output when the control ad- dress is 001. and so on. The addi- tional control address C3, is an inhibit which, when high, causes the output X to be a high impedance, effectively turning off the eight input signals to the multiplexer chip. The output of IC6 is routed to one of the inputs to IC7. Another analog switch, IC7, has 2 outputs and 4 X-Y input pairs (X0-X3 and Y0-Y3). The XO input is the output from IC6. The corresponding input YO comes from the Wilson Electrode, IC3-C. The signal from IC3-a (input 9) is the input to XI. The Wilson Elec- trode signal is also paired with input 9 on YI. In addition to the the nine signal inputs from the patient, a 1-mV test signal and a ground input are routed to the X2 and X3 inputs respectively. Ground is the Y2 input for the corresponding 1-mV signal pair as well as for the X3 ground input onY3. Two address lines, CTLA and CTLB control which input pair is switched to the outputs. That is, when the control address is 0, in- puts XO and YO are switched to outputs X and Y respectively. These control lines as well as the control signals for ICO are derived from the outputs of IC8. IC8 is a programmable array logic (PAL) IC which sequences the multiplexer address lines so that each input signal is sequen- tially passed to the multiplexer output for processing. The PAL is programmed to advance the ad- dress on control lines CO through c 5 37 4 I ICY iri. w DC 6 a 6 < I £: m ™» "l&SL t ■ T ■ si Hi -w-$ d TJ'4T^4'TT747TT*TT7J-TT7*TT7*TT7-fTT-*rT7ATT'' TT^TT" JTT74 JT74TT - * 7174717*777 JTTT-iTTTdTTr^TT - . *7T" FIG. 8— THE CONTROLLER CONTAINS A Z80-BASED COMPUTER and a digital control section which combine to provide all the sequencing, timing, and control signals for the ECG. 38 M& c 39 C3 one count each time a pulse is received on the clock input. Addi- Uonally, a decode function is pro- grammed in the PAL to control the state of the control lines CTLA and CTLB and, hence, which signal pairs from the mul- tiplexer are fed to the differential inputs of the instrumentation amplifier. The PAL timing di- agram in Fig. 6 shows the timing relationships of the input, out- put, and control signals from the PAL. The multiplexer truth table in Fig. 7 shows how the signals from the PAL are used to control the sequencing of the input sig- nals to the input of the instru- mentation amplifier. The instrumentation amplifier [IC4 and IC9-b back in Fig. 5) is one of the key signal-processing elements in the ECG design. It is a differential amplifier so its out- put is equal to the difference be- tween its two inputs multiplied by a gain. In this application, the gain is approximately 1000. The amplifier also has an input offset adjustment, R12, to com- pensate for minute differences in the input voltages, as well as an output offset capability at pin 7. In this design, the output offset at pin 7 is biased by IC5. a preci- sion voltage reference, to a con- stant voltage near 2.5 volts. When the difference between the inputs of the instrumentation amplifier is zero, the output will be 2.5 volts. As the differential input voltage changes from zero, the output of the amplifier will change from 2.5 volts by an amount equal to the input dif- ference times the gain. The final stage in the analog signal path is the isolation cir- cuitry to the A/D converter. It con- sists of lC9-a, IC16-C and IClO-d. As the voltage into IC9-a changes, the current through the LED portion of optoisolator IC16-C changes, which modu- lates the base of the light-sen- sitive transistor in the op- toisolator. That causes the collec- tor current to change, developing a voltage change across the emit- ter resistor. That voltage follows the original voltage signal at the input of IC9-a with a 180-degree phase difference. To correct the phase reversal and to compen- sate for bias and gain errors, the signal is fed through amplifier IClO-d prior to going to the con- TABLE 2— CONTROL SIGNAL DEFINITION Signal IC1 6 Output Q8 Q7 Q6 Q5 Q4 Q3 Q2 Q1 Batteries On 1 1 X X X X X X IC21WR X X X X X X X IC21CS X X X X X X X IC22WR X X X X X X X IC22CS X X X X X X X IC20CS X X X X X X X IC20RD X X X X X X X trailer board for A/D conversion. In addition to its gain function, ICl-d is also an active low-pass filter, with a cutoff frequency of about 100 Hz. A high pass filter is also imple- mented in the final stage by feed- ing the ECG signal from the emitter of IC16-C through an ac- tive low-pass filter consisting of IClO-a and its associated compo- nents. The cutoff frequency for the low-pass filter is about 0. 1 Hz, and the output is fed back through lC16-d to the positive in- put of IC9-a where it it is used to cancel frequency components of the original signal below 0.1 Hz, As a result, the frequency compo- nents of the ECG signal are lim- ited to a band between 0. 1 Hz and 100 Hz. Controller operation The controller contains a Z80- based computer and a digital control section which combine to provide all the sequencing, tim- ing, and control signals for the ECG (see Fig. 8). The Z80 micro- processor (IC1) is clocked by an 8- MHz oscillator, XTAL2. Octal bus transceivers IC2-IC5 buffer the microprocessor control, address, and data buses, and, in the case of IC5, provide bi-directional ca- pability on the data bus. Pro- grammable logic devices (PLD's) IC6. IC7, and IC8 generate vari- ous bus-control and chip-select signals to select the appropriate memory and I/O chips. The 32K x 8 EPROM (IC9) stores the CPU operating system and the ECG control program. Two 32K x 8 static RAM's, IC10 and IC11. pro- vide the CPU with 64K of RAM. Communication with the outside world is provided through a uni- versal asynchronous receiver/ transmitter (UART), IC15, and its associated line transceiver IC19. Power for most of the circuitry on the controller board is pro- vided by a 9-voIt battery (Bl) lo- cated on the front-end board. To extend battery life, the system is powered only during the time re- quired for a single ECG, with each ECG sequence initiated by depressing the reset switch. That is accomplished by powering the start-up circuitry from the RS-232 port on the PC. V^c for the power-on latch, IC26. is pro- vided by the 5-volt Zener-diode regulator, D5. When the reset switch is de- pressed, the power-on latch changes state, turning Ql on and completing the return path for" Bl. Power for the controller board is provided by the 5-volt reg- ulator, IC32. A + 6-voIt supply for the analog circuits on the con- troller board is provided by IC30, The - 6-volt supply for the analog circuitry is provided by IC29, a DC-DC converter. The two 6-volt supplies are also used to power portions of the front-end that don't require patient isolation. The remaining ICs on the con- troller board are used to generate the control signals and to digitize the ECG data from the nine pa- tient leads. Components IC13 and IC14 decode I/O instructions from the controller to produce control pulses that sequence the acquisition of the ECG data. Ta- ble 1 lists the control pulse gener- ated by each I/O port address. Each time I/O port 52 is ad- dressed, the resulting pulse clocks IC18-a, a D-type flip-flop wired to divide by two. Two out- puts to the I/O port produce a sin- gle pulse at the output of lC18-a. The pulse is passed to the clock input of ICS on the front-end board through IC14, an op- toisolator also on the front-end board. In a similar manner, a clear pulse is developed at the clear input to ICS on the front- end board when the controller continued on page 46 40 Build this inexpensive color-bar test generator and brush up on your video skills. IF YOU'RE INVOLVED IN TV SERVICING and repair, orjust enjoy tinkering around with video or amateur television, you'll be interested in this color-bar test generator. This convenient device produces an NTSC color-bar pattern that can be used for video performance testing and monitor adjust- ments. For added flexibility, just the encoder section can be used to generate composite video from your computer's RGB and sync outputs. With a dedicated color- bar generator, you can eliminate the need for a test tape or your camera — all for under $70! Before we delve into the theory behind the color-bar generator. THOMAS GOULD WB6P let's briefly discuss the various components that make up the composite NTSC video signal: synchronization, luminance, and chrominance information. The NTSC signal A typical NTSC composite color video signal is shown in Fig. 1-a. [NTSC is the National Television Systems Committee, who has set the standards for color encoding and decoding systems in the U.S. since 1953.) The picture on a color TV is formed by three elec- tron beams of varying ampli- tudes and phases: red. blue, and green. Each of those beams are scanned horizontally and ver- tically over the screen. As the beams scan, their currents and amplitudes change to create the light and dark areas on the pic- ture-tube face and form the im- age that you see displayed on the screen. The composite video signal is made up of three basic compo- nents: the scan control informa- tion called the synchronizing pulses (Fig. 1-b), the luminance signal, which is the brightness information and is often referred to as the Y signal (Fig. 1-c). and the color information called the chrominance signal (Fig. 1-d). Let's briefly discuss each type of video information. 41 WHITE - 63.5m s- a - HORIZONTAL SYNC u SYNCHRONIZING COMPONENTS -LUMINANCE SIGNAL BLACK-AND-WHITE INFORMATION COLOR INFORMATION -COLORBURST FIG. 1— A COMPOSITE VIDEO SIGNAL (a) includes sync pulses (b), black-and-white information (e), and the colorburst signal (d). Synchronizing components In order for a picture to be re- produced properly, the TV re- ceiver must scan its screen exactly in step with the camera in the studio. To make sure the camera and the receiver are syn- chronized, a series of pulses are sent to the camera telling it when to start at the top of the screen and when to begin a new line at the left of the screen. Those same pulses are sent to the receiver along with the video informa- tion. The signals that tell the camera and receiver when to w o z o tz h- o HI -J 111 6 c < COMPOSITE SYNC TP1 SYNC GENERATOR CLOCK >TP2 :> COMPOSITE,, TO . BLANKING f 1 ^ 3 "K. (J2B) RED fJ2C) GREEN [ (J2D1 BLUE COLOR I -V encoder;. TP12 COMPOSITE VIDEO OUTPUT i> RGB GENERATOR FIG. 2 — A BLOCK DIAGRAM of the color-bar generator shows the main components of the circuit: RCA's CD22402E sync generator and Motorola's MC1377P color encoder. start at (he top are called vertical sync pulses, while those that start scanning each line at the left are known as horizontal sync pulses. In the NTSC system, each frame, of complete video image, contains 525 lines. That is ac- complished by horizontally scan- ning at approximately 15.750 lines per second, and vertically scanning at 30 frames per sec- ond. (The vertical scan rate is ac- tually 60 Hz, but it takes two trips, or fields, down the screen to complete one frame.) The pro- cess of returning to start a new scan is called retrace or flyback. Luminance Black and white information is contained in the Y or luminance signal, which determines the in- stantaneous brightness of the electron beams as they scan over the screen. In fact, it is all that is used for the single electron beam in a black-and-white TV set. A negative-going video detector de- tects a luminance signal in which the negative signal ex- tremes correspond to bright areas of the picture. The wave- form shown in Fig. 1-c would, therefore, produce vertical bars of decreasing brightness from left to right. Note that the output is black during retrace so the electron beams will not be seen. In the NTSC color system, the Y signal is made from the red, green, and blue cameras by an additive technique: 30% of the red signal, 59% of the green sig- nal, and 11% of the blue signal are added together to form the Y signal. The luminance signal can also be expressed as E Y =.30E H + .59E G + .11E B where E K , E G , and E B are the volt- ages of the red. blue, and green signals, respectively. The combination of different amplitudes of color signals is what determines the various shades of gray in a monochrome receiver — white having a lumi- nance of one, black a luminance of zero. The ability of a receiver to determine a corresponding level of gray from color levels is an im- portant feature in the com- patibility of color and mono- chrome TVs because the black- and-white signals can be ob- tained from the three primary color signals. 42 FIG. 3— SCHEMATIC OF THE COLOR-8 AR GENERATOR. Sync generator IC5 provides the composite-sync timing signals, color encoder SC6 takes the separate red, green, and blue video signals and composite sync to generate the composite video signal. All resistors are v.;- watt, 5%, unless Motorola otherwise indicated. Other components R1.R14, R15— 4700 ohms L1— 400-ns delay line (TK1001) R2— 56,000 ohms L2— 30 u-H, 2.52-MHz transformer R3 — 6800 ohms (TK1603) R4, R5— 1200 ohms XTAL1— 3.58-MHz colorburst crystal R6— 220 ohms XTAL2 — 503-kHz ceramic resonator R7 — 75 ohms Miscellaneous: enclosure, stand- R8-R10— 5000-ohm potentiometer offs for mounting circuit board, 4- R16 — 1 megohm pin friction-lock connector for J1, Capacitors straight-header connector for J2, C1-C4, C10, C20, C24, C25— 0.1 jj.F, bi- 2-pin friction- lock connector for J3, polar electrolytic four shorting jumpers, wire, solder. C5, C8— 1000 pF, mica etc. C6. C7— 0.01 (j.F, bi-polar electrolytic C9, C18, C19— 100 pF. mica Note: The following items are C11 — 47 pF. mica available from Geko Labs, 13019 C12— 2-12 pF variable ceramic capacitor 250th Place SE., Issaquah. WA C26 — 10 pF, mica 98027-6730, (206) 392-0638: C13, C14— 220 pF, mica etched, drilled and plated- C15-C17— 15 jiF, electrolytic th rough PC board $30.00; a com- Semiconductors plete kit including all parts, PC IC1- — 74LS163 counter Board, and assembly instruc- 1C2— 74L02 quad nor gate tions S80.00; a complete as- IC3— 74LS74 flip-Hop sembled and tested unit 5125. IC4— not used Add $5.00 S & H with any order. IC5— CD22402 sync generator, RCA Washington residents add 8.1% IC6— -MC1377 color encoder, sales tax. Chrominance The color information, or chro- minance, [which is ignored in a black-and-white TV) is made up of red, blue, and green signals re- quired to drive the picture tube, minus the luminance signal. Those "color-difference" signals are designated as R— Y {red minus Y), and B - Y (blue minus Y). Color-difference signals are used solely for color reproduc- tion. A special matrix circuit in the receiver can extract a G-Y (green minus Y) signal from the B-Y and R-Y signals. The ad- vantage of changing the color sig- nals into color-difference signals is the reduction of three color sig- nals into two. The R-Y B-Y, and G-Y sig- nals are decoded at the receiver by adding the Y signal back to each of the difference signals. A 3. 5 8-MHz subcarrier is sent by the transmitter and used in the receiver to restore the original color information. The frequency and phase angle of the 3.58-MHz subcarrier in the receiver must be the same as that c 5° to 43 CLK TP20OTP5 1.0 - Og y z o or P o LU _l Lil g Q < J2C GRLEN V 1.0+- J2B RED l—i- t Vp 1.0 p I J2D BLUE I ^ t FIG. 4— OUTPUT SIGNALS of the color- bar generator. The TTL signals are re- duced to 1 V p-p by B8. R9, and R10. in the transmitter for proper color reproduction. Syn- chronization is performed by transmitting a small sample of the 3.58-MHz subearrier during the horizontal snyc pulse. That color sync interval is also known as the colorburst. The colorburst signal is used as a reference to synchronize the phase and am- plitude of the color subearrier. The colorburst also determines the tint and saturation of the color that is displayed. Theory of operation Figure 2 shows a block di- agram, and Fig. 3 a schematic of our video generator. Sync gener- ator IC5 is used to provide the composite-sync timing signals. The outputs are composite sync, composite blanking, and a buff- ered output of the sync oscillator. The sync generator uses a 503- kHz ceramic resonator (XTAL2) as a base oscillator. The 503-kHz frequency is divided by 32 for the horizontal sync, and is further divided to derive the vertical sync-timing signals. Those sig- nals are all combined into the composite-sync signal which is sent to the MC131377 color en- coder (IC6). The color encoder takes the separate red, green, and blue video signals and com- posite sync to generate the com- posite-video signal. XTAL2 £19 4Qh CT8 r r — «" IC5 2EIOC0MP SYNC TP1 ID 0f RIO L1 C25 R-i C17 f ' R14 TP4 TP8 BLANK it; ft C16 4- C15 ibT>:: ■ R4C 16 [D U I ] ■ K-6 rU[]] t J_ ! -R73- C7 dss9 w XTAL1 '' C2 C9/V . TP6 TP12 -^OV SYNC TP7 FIG. 5— PARTS PLACEMENT DIAGRAM of the color-bar generator. The 3.58-MHz colorburst crys- tal, XTAL1, is the reference os- cillator for the chroma informa- tion. Capacitor C12 allows fine tuning of the reference oscillator to be exactly 3.579545 MHz. The combination of R2 and C5 set the timing for the insertion of the colorburst signal on the back porch of the composite video sig- nal. The values used for R2 and C5 set the burst timing to ap- proximately 0.4 u,s after sync, and a burst width of 0.6 u.s. The network of L2, C9, R6, C8, Cll, and R3 provide bandpass filter- ing for the chroma component. A delay for the luminance channel (-Y) is provided by R4, LI. and R5 to compensate for the internal delay of the chroma signal. RGB generators IC1. IC2, and 1C3 make up the red, green, and blue video signals that drive the video encoder section to make the color bars. One half of IC 1 is used as a divide-by-2 counter, which generates the 252-kHz clock for the four-bit counter tCl. The non-inverted blue, red, and green signals are the divide-by-4, -8, and -16 outputs of IC1, respec- tively. The blue, red, and green signals are inverted, and blank- ing is added by 1C2. The TTL level is reduced to 1 volt p-p by R8, R9, and RIO, as shown in Fig. 4. Construction The video generator uses a double-sided PC board that is available from the source men- tioned in the parts list. We recom- mend that you use a PC board for this project because the frequen- cies involved require a large ground plane. Both the compo- nent and the solder side of the PC board are shown in the article if you wish to make it yourself. Construction is fairly straight- forward. Install all components according to the parts placement diagram shown in Fig. 5. Make sure C15-C17 are inserted into the board with correct polarities. Install all ICs last, observing cor- rect orientation. Since the ICs are static sensitive, make sure you follow the manufacturer's recommendations for proper handling. Checkout The measurements listed in this section will help to make sure the video generator is work- ing properly. The power on tests should be made with the + 12- and + 5-V power sources on. Set R8, R9, and RIO to mid range. If you are the impatient type you can go right to the video output test point TP12 and see what you get. If you're lucky you'll have a video signal that probably needs some adjustments. If that's the case you can proceed directly to the video adjustments section. If not. proceed slowly through the following steps to isolate the problem and verify each of the listed voltages, frequencies and waveforms. Keep in mind that you will need an oscilloscope for the video level adjustments. • Pin 2 of Jl and +5 V— > 2000 ohms (power off) • Pin 4 of Jl and + 12 V— > 1 megohm [power off) Power-on Tests • + 12-V supply— 57 mA • + 5-V supply— 29 mA • IC1 pin 16— + 5 V • IC2pin 14— + 5 V • IC3pinl4— +5 V 44 FOIL PATTERN OF THE COMPONENT side of the double-sided PC board. 81-0101-1 • • • •- • — *J 2zJ* lfej*V • • FOIL PATTERN OF THE SOLDER SIDE of the PC board. -6'ftlNCHES- • IC5pln 19— + 5 V • IC5 pin 6 (TP2)— 2.504-kHz, 5- V p-p (TTL level) square wave • IC5 pin 5 (TP1)— TTL-level composite-sync signal • IC5 pin 13 (TP4)— TTL-level blanking signal • IC3 pin 5 (TP5)— 252-kHz signal • IC1 pins 11-13 (TP6. 7, 8)— Di- vided down signals Sync Generator • IC5pin 19— + 5 V • IC5 pin 5 (TP1)— TTL-level composite- sync signal • IC5 pin 6 (TP2J— 504-kHz. 5-V p-p TTL-level square wave • IC5 pin 13 (TP4)— TTL-level blanking signal RGB Generator • IC1 pin 16— + 5 V • IC2pin 14— + 5 V • IC3pinl4— + 5 V • IC3 pin 5 (TP5)— 252-kHz signal • IC1 pins 11-13 {TP6, 7 and Si- Divided down signals as shown in Fig. 4 Color Encoder • IC6pinl4— +12V • IC6 pin 2— TTL-level com- posite-sync signal (Fig. 1-b) Amateur Television Quarterly This article originally appeared in ATVQ magazine. ATVQ is a quarterly publication featuring technical articles on subjects re- lated to ham radio, including VHF, UHF, amateur TV (ATV), computer programs, and repeater projects, ATVQ is enjoyed by hams of all levels, from beginner to Extra class. A subscription to this magazine is available for $15 per year, $4.00 for a sam- ple copy (Visa and Mastercard are accept- ed). For more information contact Amateur Television Quarterly 1545 Lee St. #73 Des Plaines, lL 60018 (708) 298-2269 • IC6 pins 3-5—1 V p-p signal • IC6 pins 17 and 18— 3.58-MHz oscillator signal • IC6pin 16— 8.2 VDC • IC6 pin 1 — Ramp signal • IC6 pins 10 and 13— Chroma signal (Fig. 1-d) • IC6 pins 6 and 8 — Luminance signal (Fig. 1-c) • IC6 pin 9—2 V p-p (Fig. La signal) Video Level Adjustments • IC6 pin 4 (J2C)— Adjust R8 to 1 Vp-p • IC6 pin 3 (J2B(— Adjust RIO to IV p-p • IC6 pin 5 (J2D)— Adjust R9 to 1 Vp-p • J3 pin 1 — Terminate into a 75- ohm connector • Video Output (TP12)— Com- posite 1-V p-p signal. 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Also includes all the info you'll need regarding the BUSINESS-SIDE of running a successful service op- eration! fREE | NF p HMAT | nN CALL TOLL-FREE 1 -800-53 7- 05 89 Or write to: Viejo Publications Inc. 5329 Fountain Ave. Los Angeles. CA 90029 Dept. RE CIRCLE 187 ON FREE INFORMATION CARD •^SS5i^S»* «&*&**# *»*» ?w ,(rt?> $$> ,»* WS" CIRCLE 108 ON FREE INFORMATION CARD ECG continued (row page 40 addresses I/O port 53. These two pulses control the operation of the ECG signal multiplexer. The other two pulses produced at IC14 when the controller ad- dresses I/O ports 54 and 55 are used to latch data into octal latches IC16 and IC17. Data latch IC17 stores data for the D/A converters IC21 and IC22. Latch IC16 is used to derive additional control signals. Table 2 shows that to turn both batteries on and to place the other control signals in an inac- tive state, all output bits of IC16 must be a 1. To achieve that, the CPU must output 255 to I/O port 54. To subsequently activate, or lower, any of the control bits without disturbing the other bits or turning off the battery power, all bits must be high except for the one corresponding to the ac- tivated control signal. After the appropriate bits in IC24 have been activated, the CPU must re- turn them to their inactive state by sending 255 to I/O port 54. The same logic applies to the other signals in Table 2. To see how this all works to- gether in the circuit, lets assume we need to turn on both the positive and negative battery- powered supplies on the front- end board, and write a 127 to IC21 on the controller board. First, the CPU outputs a 255 to I/O port 54. That places a "1" at all outputs of IC16. The "1" at Q8 of IC16 produces a current flow in the LED of optoisolator IC16-a, causing current to flow through its associated transistor. The en- suing voltage drop across R60 turns FET Ql on, completing the battery input circuit to the -6- volt regulator, IC11. The negative supply is now on. The positive supplies are turned on by the "1" onQ7ofIC16. Now the CPU must place our arbitrarily chosen value. 127, into the octal latch, IC17. on the controller board. As shown in Ta- ble 1, that is accomplished by writing 127 to I/O port 55. Once the correct number is in the latch, the CPU must write it to the D/A converter. Notice that the outputs of the octal latch, IC17, continued on page 88 GERARD ROBIDOUX AND ROBERT DMITROCA* LAST MONTH WE INTRODUCED THE 16- channel, 50-MHz logic analyzer. We discussed ail the capabilities of this digital-test instrument, and the theory behind its opera- tion. This month we'll show you how to build it. Construction The logic analyzer consists of two PC boards, a case, and an overlay. Due to the extremely high-speed logic used in this de- sign, it is critical that PCB's be used. Wire-wrap and point-to- point construction techniques will not work! A photo of the inside of an as- sembled unit is shown in Fig. 7. The main logic board has four cir- cuit layers: two sig- nal layers, one power, and one ground plane. The PC board can only be fabricated bv fhh fairly sophistica board vendor. Be- cause of that, foil patterns have not been provided in this article. A finished board and all the required parts, however, are available from the source mentioned in the Parts List. Figure 8 shows an internal photo of the unit with the LCD panel re- moved. Figure 9 shows the parts-place- ment diagram. Make sure you ob- serve the correct component orientation and capacitor polar- ities when soldering the compo- nents. Assemble the keyboard first, because it is the simplest circuit. Note how the keys are placed on the component side of the circuit board, as shown in Fig. 9. The keyboard connector. PI, must be placed on the solder side, in the position that is shown. When soldering the keys, SI— SI 2. pay particular attention "Gerard Robidoux and Robert Dmitroca are I m I 1 1 1 '.-. Bsl I ItMlt'i-klfl TiBKto ( : f 1 1 k-m: V. ti I ivj consulting company specializing in the de- sign of low-cost test instrumentation. Troubleshooting digital circuits is a cinch with this 16-channel, 50-MHz logic analyzer. CONVENTION SYSTEMS ATSTtU WAVE SETUP STATE I I to their alignment. They must be straight with respect to the edge of the board and to each .other, otherwise the cutouts in (he case ' will not fit over them. When you've finished solderiR, in the components, all flux must be removed from the clrcui boards. We recommend that sol der with a water-soluble ilux b used, rather than (he standard rosin core. Rosin-core flux must be removed with a freon based solvent, which is quite expen- sive. Water-soluble (lux. however, can be cleaned off with warm tap water and a small brush (a tooth- brush is remarkably effective). Kester solder with type 331 flux is a good one to use. Assembling the main circuit board is also straightforward. In- stall all mechanical components as shown in Fig. 10. Most of the components on the main board are CMOS, therefore they're quite positive to static electricity, lake sure you follow adequate recautions when handling lose ICs. When assembling the main board, it is critical that you use a properly grounded three- wire soldering iron, and that your workbench is covered with an anti-static mat to avoid damage to the CMOS ICs. Solder in all of the ICs and sockets first. Notice that IC1. IC2. IC30, IC32, IC40, 1C44. IC45. and IC46 are socketed. The sock- et for IC30 has pin 1 facing to the left. The socket for 1C40 is a Dallas Semiconductor Smart Socket. It does not use all of the 240x64-PIXEL LCD 16-CKANNEL PROBE ASSEMBLY g z c £ o D < VOLTAGE REGULATOR IC43 KEYSS1-S12 FIG. 7 — INTERNAL PHOTO OF the logic analyzer. The main PC board has four layers: two signal layers, one power, and one ground plane. Wire wrap and point-to-point soldering techniques cannot be used because of extremely high-speed logic. holes provided for IC40. Align that part in the lower part of the socket. The capacitors and resistors should then be added, followed by connectors J 1^J4, PI, and the header blocks P2-P4. Attach the heats ink to the voltage regulator, IC43, using a thin layer of con- ductive heat -sink cream. Secure that assembly to the board using Vb-inch 4-40 screws, washers, and nuts. The circuit board must be jum- pered to work properly with the size of SRAM and ROM being used. To accomplish that place shorting blocks between P2 (pins 1-2), P3 (pins 2-3). and P4 (pins 2-3). That completes the assembly of the main logic board. After clean- ing the board of flux, carefully in- spect it for good solder connec- tions and make sure there are no solder bridges present. Touch Lip any cold or questionable solder joints. Carefully inspect the align- ment of all of the components. Insert the V25 microprocessor (IC30) into its socket. Make sure that pin I is aligned correctly. It's very difficult to remove a PLCC device from the socket once it's been inserted. Insert compo- nents IC1, IC11. IC44. IC45, and IC46. IC44 and IC45 are pro- grammable logic devices (PLD's). Acquisition connector The acquisition clip assembly consists of a DB-37 connector shell containing eighteen wires terminating in small micro-clips. It is supplied in a pre-assembled format. There are three separate parts to each micro-clip assembly; the wire, the body, and the plunger. Each part can have a different color. The color coding is used to separate the function of the in- put lines; all data input channels have a white wire, the clock wire is green, the ground wire is black. The plunger and body are used to distinguish the input channel numbers. Channel has a black plunger and a black body, chan- nel 1 has a brown plunger and a black body, channel 2 has a red plunger and a black body, and so on. Table 1 lists the cap, plunger, and wire color coding of the probe assembly. FIG. 8— INTERNAL PHOTO OF the logic analyzer with the LCD panel removed. Final assembly We're now ready for final as- sembly. To connect the LCD panel to the main logic board, con- nector P4 must be soldered onto the display. Connect P4 to the bottom side of the LCD panel (away from the LCD panel itself). To complete the mechanical as- sembly, attach four Vs-inch and four %-inch standoffs to the cir- cuit board as shown in Fig. 10. The shorter standoffs are used for the keyboard. Align the key- board connector and attach it to the main circuit board. Do the same for the LCD panel. Checkout At this point we're ready to test the logic analyzer. Measure the resistance between pin 20 and pin 10 of IC1 (the power pins). The resistance should be above 20 ohms. If it's below that value, there's a short somewhere on the board. Do not power the unit up until you find it! Plug the AC adapter into the wall outlet then plug it into J2. The LCD panel should display a brief title-page before running the software. {You can become fa- miliar with the software running on the logic analyzer by reviewing the introductory sections in the manual provided with the kit or with the ROM). If you don't see the title page, then there's a prob- lem with the microprocessor sec- tion (IC30, IC40, IC42, IC44, and IC46). The LCD contrast voltage at RIO should be around - 10 volts. The voltage at IC1 pin 20 ( + 5-volt power supply) should be between 4.75 and 5.1 volts. We will now test the internal clock generator circuits. For that test, you'll need a 100-MHz coun- ter. Connect the counter to pin 5 of IC38. Go to the system screen and select an internal clock. Then select each clock speed in turn. For each clock speed, make sure the counter shows the same speed on the display (for exam- ple, if a 10-MHz clock has been selected, the counter should show 10 MHz). You can check the external clock signal input by selecting the external clock function. Using a function generator, place a TTL-level signal of a known fre- quency into the clk pod. The counter should show the func- tion generator's frequency. 48 R11 *. IC31 ~^7 tC32 -C42- -C43- -C44- -C45- -C46- -C47- IC33 IC34 IC35 w ^ er- icas ■ IC36 fC37 1C39 IG40 ' I ■ ■■ IC46 -4 III'— ■ .. * i!l+ l J : 5§J IC41 C55 C56 C57 h IC4g J^ FIG. 10— THE ASSEMBLY DRAWING SHOWS how the case is secured together. 49 .:~JQOOCKV- ( LbCkft*«7CS432l £• # PARTS LIST o z O (T (- O 111 6 D < THE SETUP SCREEN is shown in the lop display. The bottom screen shows a large block indicating the size and position of data and its location relative to the entire acquisition data. Go to the search field on the setup screen. Select it using the sel key, and change it to the input item. Make sure the acquisition clip assembly is connected to the logic analyzer. Briefly touch each input channel clip to the ground clip. That grounds the channel. Verify the display shows a low symbol, when the clip is touch- ing the ground clip, and a high symbol, when the clip is not touching. That verification tests the input buffers, acquisition RAM, and microprocessor inter- face. All we have left to test is the trigger logic. First set the trigger word to all "l's" (for example, TRIGGER ="11 1111 11 11 111 111"). Press the run key. Two messages should flash briefly on the screen, and the logic analyzer should return to you imme- diately. Now set the trigger to "111111111111110" (trigger when channel 1 is low and all others are high). Press run. The "WAIT- ING FOR TRIGGER CONDITION" message should remain on the screen until the channel ciip is touched to the ground clip. Re- peat that procedure for all sixteen channels. All of the circuits have now been tested. Now it's time to put the circuit boards into a case, which comes in four pieces; the top, bottom, and side panels. The top and bot- tom halves of the case contain grooves on the front and back. It "s important that the boards be placed with the keyboard closest to the side with the raised groove of the bottom piece. The main cir- cuit board will fit tightly over four plastic standoffs which have been molded into the bottom of the case. It may be necessary to press firmly on the circuit board to force the holes over the stand- All resistors are 14- watt, 5%, unless otherwise indicated. R1-R8-10.000 ohms R9-^t70 ohms R10 — ohms, or jumper wire RA1. RA2— 1 megohm, 1 0-pin bussed SIP resistor array Capacitors C1-C11. C13-C20, C23. C25, C27-C38, C40-C49. C58-C60— 0.1 nF ceramic axial C12, C24— 3.3 \if, 10-volt tantalum C21 , C22— 10 pF, ceramic disc C26 — 100 nR 25-volt tantalum C39 — 50 pF, ceramic disc C50-C57— 22 (j.F, electrolytic Semiconductors IC1, IC11— 74ACT574 8-bit latch IC2, IC3, IC12. IC13— 74ACT00 quad 2- input nand gate IC4, IC14— 74ACT521 8-bit comparator IC5, IC15— CY7C128A 2K x 8 15-ns static RAM (SRAM) IC6, IC16 — 74HCT245 octal transceivers IC7-IC9, IC17. IC18, IC39— 74HCT5748- bit latch IC10— 74F85 4-bit comparator IC19, IC22-IC27— 74ACT163 4-bit coun- ter 1C20— 74HCT138 3-to-8 demultiplexer tC21 — TL7705A voltage supervisor and reset control IC28— 74ACT74 dual D-type flip-flop IC29— 74ACT02 quad 2-input NOR gate IC30— V25 high-integration micro- processor IC31 — 74F32 quad 2-input or gate IC32— 74ACT86 quad 2-input xor gate IC33— 74F160 4-bit counter IC34 — 74ACT153 dual 4-to-1 multiplexer IC35-IC37— 74LS390 dual bi-quinary counter IC38— 74ACT151 8-to-1 mutiplexer IC40— Dallas Semiconductor DS1213C "Smart Socket" and 32Kx8 100-ns SRAM or Dallas Semiconductor DS1235 integrated battery backed RAM offs. The two side pieces can then be slipped over the connectors on the appropriate ends. After that's been done, the top piece is slipped over the keyboard and at- tached to the bottom piece using four self-tapping screws. At this point, make sure the keyboard and display are straight with respect to the edges of their cutouts. The overlay must now be applied to the top piece. The wax paper sheet on the back of the overlay must be re- moved to reveal the pressure-sen- sitive backing. A word of caution regarding the glue used: once it's been IC41, IC42— MAX232 RS-232 tranceiver and charge pump IC43— 7805 5-volt regulator IC44— GAL16V8-15LP PLD IC45— GAL16V8-10LP PLD IC46— 128K x 8 250-ns EPROM LCD panel— Sharp part no, LM24014W Other components XTAL1— 16-MHz HC-49 crystal XTAL2— 20-MHz 14-pin DIP package os- cillator XTAL3— 50-MHz 14-pin DIP package os- cillator Case—Pactec CM69-120 Key switches (12)— 75120-002.0000 AC adapter— 9 VDC at 1 amp secondary output Connectors J1— Right-angle DB37 connector P2-P4— 3-pin socket strip J3 — Right-angle DB9 connector J4— 20-pin socket strip (2 x 10) P1 — 7-pin socket strip (1 x 7) J 2 — Power connector (2.3-mm barrel) Keyboard — 7 x 1 row- header Acquisition clip— DB37 connector with 18 wires and micro-clips. P1 — 2 x 10 row-header connector for LCD panel Sockets 20-pin machined sockets for IC1 andlCIl 32-ptn socket for IC46 14-pin machined socket for IC32 84-pin PLCC socket for IC30 Hardware 4 H-inch standoffs with 4-40 internal thread 4 %-inch standoffs with 4-40 internal thread 18 4-40 screws with pan head, '/4-inch length 2 4-40 nuts 1 TO-3 heatsink and heatsink grease pressed down on the case the overlay, it cannot be moved with- out destroying the overlay and the case. This glue has no respect for mistakes! Peel the entire wax paper sheet off. Use great care in positioning the overlay over the keys of the keyboard. Make cer- tain that the overlay is true to the edge of the case. Gently press the overlay down. At this point it's still possible to move the overlay, but once pressure is applied, however, the overlay cannot be moved. Working from the center of the overlay out, smooth the overlay down, being careful not to catch air bubbles. 50 TABLE 1— PROBE ASSEMBLY ORDERING INFORMATION Connector Pin No. Cap Color Plunger Color Wire Color 1 (GND) Black Black Black 4 (AQ14) Brown Yellow White 5 (AQ13) Brown Orange White 7 (AQ10) Brown Black White 8 (AQ09) Black White White 10 (AQ06) Black Blue White 11 (AQ05) Black Green White 13 (AQ02) Black Red White 14 (AQ01) Black Brown White 21 (CLK) Green Green Green 22{AQ15) Brown Green White 24 (AQ12) Brown Red White 25{AQ11) Brown Brown White 27 (AQ08) Black Grey White 28 (AQ07) Black Purple White 30 (AQ04) Black Yellow White 31 (AQ03) Black Orange White 33 (AQO) Black Black White *Pins not listed are unused. Software The software which controls the logic analyzer is quite sophis- ticated and very complex. Since a thorough examination of it is beyond the scope of this article we'll only present the highlights of the software interface. The software listing is. however, available on the RE-BBS (516-293-2283, modem settings: 1200/2400, 8N1. file name: LAI 50. ARC). More information on the operation of the analyzer can be found in the user's guide. That document is provided with every kit or assembled unit, as well as with the separate ROM's, from the source in the Parts List. Here are some of the special features that the software offers: • User Interface — The logic ana- lyzer has a friendly, consistent user interface. Pull-down and pop-up menus, form menus, and selection boxes enable you to easily configure the analyzer. Four distinct screens allow you to interact with the logic analyzer. Each portion of the screen is as- sociated with one of the system, setup, wave and state keys. • System Screen — Most system- wide parameters are set up using this screen. The configuration name, clock type, clock speed, trigger position, and threshold level are always displayed. A pull- down menu is provided which al- lows you to change communica- tion and printer parameters. • Setup Screen — The trigger word, search word, and acquisi- tion line groups are defined in this screen. An input-line monitor allows you to view the current state of the input lines without having to start the ac- quisition cycle again. • Waveform Screen — Displays the contents of the acquisition data buffer in graphical format. Two cursors are provided which let you determine the time rela- tionships between signals. A pull-down menu is provided which allows you to jump to a particular location within the data, search for a pattern, or print out a continuous range of data. • State Screen — Displays the contents of the acquisition data buffer in tabular format. Two cur- sors are provided which let you quickly determine the time rela- tionships between signals. A pull-down menu, identical to that of the waveform screen, is also provided. • On-Line Help — The logic ana- lyzer contains a true context-sen- sitive on-line help system. Help is always available at the touch of Note: The following items are available from Convention Sys- tems, 1214-315 Southampton Dr. SW, Calgary AB, Canada T2W 2T6, (403) 253-4427. Send check or money order. Shipping is by ground delivery. Contact Conven- tion Systems for additional charges if overnight del i very is de- si red. All items are postpaid, ex- cept as noted. • Etched, drilled and plated main and keyboard PC boards — $99.00. • Preprogrammed EPROM, GAL16V8-15LP, and GAL16V8- 10LP (IC44-IC46)— $99.00 • Milled-out case with plastic overlay — $79.00. • Probe assembly— $99.00 • AC adapter— $15.00 • LCD panel— $150.00 • IC30 V25 microprocessor — $29.00 • Manual— $32.00 • Complete kit, including probe assembly and AC adapter — $695.00 plus $20.00 S & H. • A complete assembled unit, in- cluding probe assembly and AC adapter— $695.00 plus $20.00 shipping and handling. the help key. Help is always given about the item that is currently highlighted. • RS-232 Interface— The logic analyzer contains a serial RS-232 interface for connecting with ex- ternal devices. The baud rate, data bits, stop bits, parity, and protocol can all be configured using this interface. • Printer Support — A serial printer can be connected directly to the analyzer. All or part of the acquisition data may be printed out in waveform or state format. All formatting of the output is handied by the logic analyzer. • Slave-Mode Operation— The logic analyzer can be controlled by a host or remote computer, therefore, it can be used in an automated test environment. Ac- quisition data and configuration settings can be downloaded to the host computer for storage and further manipulation. A li- brary of IBM-PC based interface routines is provided with the log- ic analyzer. The next time you find a prob- lem with one of your digital de- signs, use the logic analyzer to quickly and effectively find the problem. You'll wonder how you ever did without it! R-e 5 51 o z o £ F o o Q < In previous installments we built computer-assisted test instruments to measure voltage. resistance, and capacitance. In this final installment, we'll round out our component inspection system (CIS) with a PC-based IC tester. Our tester can test all 14- and 16-pin CMOS and TTL ICs. It can also be modified to test any IC that requires digital inputs and provides digital outputs. Testing methods There are two common ways of testing digital circuits and ICs: transition and state testing. In transition testing, you provide a series of signals to the circuit and note the output transitions. Transition testing is beneficial when you are interested in the AC characteristics (slew rate, propa- gation time, etc.) of a circuit. Transition testing is, however, expensive and time-consuming. With state testing, you change one input at a time and note any changes in the outputs. State testing can't check the high- speed response of an IC, but it does allow you to exercise an IC and determine whether it's good or bad. Our tester uses the tech- nique of state-testing. Specifications An IC may be fully specified by a connection diagram, a block (or function) diagram, and a truth table. The connection diagram shows the physical layout and name of each pin. The block di- agram shows the internal func- tions of the IC. The truth table lists outputs provided by various input combinations. For example. Fig. 1 shows a connection diagram (a), function diagram (b), and truth table (c) for a 4011 CMOS quad two-input nand gate. The connection di- agram shows that the 4011 is a 14-pin IC with ground (V ss ) at pin 7 and +V (V DD ) at pin 14. The other pins are labelled as well, but to And out what the la- bels mean, we must refer to the functional diagram (Fig. 1-b). Here we see four nand gates, each with two inputs (A and B) and one output (Y). To find out how each gate works, we must exam- ine the truth table (Fig. 1-c). For each gate, the output is high un- less both inputs are high, in which case, the output is low. Testing steps Using the connection and functional diagrams, as well as the truth table, we must follow four steps to test an IC. 1. Determine its pinout, its logic functions, and its truth table. 2. Specify a series of inputs to exercise all of the functions. 3. Determine the proper outputs for each input combination. 4. Perform physical testing. You get pinout, functional, and truth-table information from data books, which can be pur- chased from IC distributors. (They are also available at larger local libraries). Using that infor- mation, you then plan a series of inputs. Using the truth table as a guide, step through each of the possible inputs (or as many as necessary to determine proper function) and determine the proper outputs, A programming form (like that shown in Fig, 2) can be helpful in setting up a test program. After setting up a test program, it's time to perform a physical test. Physical testing includes these four steps: 1. Initialize the IC to a predeter- mined state. 2. Apply inputs. 3. Monitor outputs. 4. Compare to what should oc- cur; determine pass or fail. For example. Fig, 2 shows a test program for the 4011. That pro- gram first initializes all inputs high. Actually, any initialization is fine (all inputs low, for exam- ple) as long as testing begins in a known, repeatable state. The ac- tual test begins at step 9. One input on each gate is brought low, changing that gate's output from low to high. Then the input is returned low, making the output also return low. The tester For maximum flexibility, we designed a simple interface card, shown in Fig. 3. The heart of our card is a standard 8255 (IC2); the only other active component is a 74LS138 decoder (IC1) that al- lows you to choose an I/O port for communicating with the card. To avoid conflicts with other hard- ware devices, DIP switch SI al- lows you to choose one of several different ports, ranging from 512 through 736 decimal. The 8255 can function in sev- PcIC Test Fixture eral modes; we use Mode 0, in which each eight-bit register (PA, PB, and PC) can be programmed for input or output. A separate control register specifies how the data registers work. If we program PA and PC as outputs and PB as input, we have eight inputs and 14 outputs. Conversely, programming PA and PC as inputs and PB as outputs gives us eight outputs and 14 in- puts. With these two pos- sibilities, we can test any 14- or 16-pin IC with any combination of inputs and outputs. A standard 25-pin cable con- nects J2 on the I/O board in the PC to the test fixture, shown in Fig. 4, which consists of Jl, two solderless breadboards, and SOI, a 16-pin zero-insertion-force (ZIF) socket. That arrangement allows any of the 24 lines from Jl to be connected to any of the 16 pins on SOI with jumper wires. Software All our test and control pro- grams are written in BASIC. Un- fortunately there is not enough space to present complete list- ings, but we will provide enough sample code so that you can un- derstand the principles involved. In addition, we'll post compiled programs on the RE-BBS (516-293-2283, 1200/2400, 8N1; look for file PCTEST3.ZIP); soft- ware is also available on disk di- rectly from the author, as discussed in the parts list. 52 EXPERIMENTING WITH PC- BASED TEST EQUIPMENT DQea0fl00'9C0U4O000OCCCiC"000iQ0C^Cii>0QQOCUOOa0D00000O0OO POeOCB6BiiettWt;VOOOSOOOOOOO'lJytj(iOCt.'t^*,HH)(JOsJ'iJgiJiiViOOOOOOOqOtJO Dg«B99eooflQOOuooco(>ocouot,\'vvvuao^guocaoaooooi>ioooooocooo ts *-.,-. ^. rt <-ij-. rt rt i-, qq r; t »c- c co"' 1 o oo o o o o PcIC I/O Board! Itllllli auOOODOOuCCiODOODODODOOOC/ ■ ■»- t .M-t.M t - t . t - M. M . M -M .i The software needs to know the port address of the tester. If we define A as the address of PA (the decimal address selected by SI). thenB = A + l. C = B + l.and D = C + 1, where B is PB, C is PC. and D is the control register. For example, if SI is set for address 640. then: 10 A = 640: B = 641: C = 642: D = 643 Now, to set up the 8255 PPI. we must send an appropriate value to the control register. For PA = output, PB = input, and PC = output, that value is 130. For PA = input, PB = output, PC = input, the value is 153. For example, to set PA and PC as out- puts, and PB as input, then: 20 OUT D, 130 After setting up the 8255, we can send and receive information to and from the registers. For ex- ample, to bring PA lines PA0 and PA2 high, and then sense those lines to make sure everything is working correctly: 30 OUT A, 5 40 IF INP(A) 5 THEN PRINT "There's A Problem With PA'VEND 50 IF INP(A) = 5 THEN PRINT "Peripheral Register A is OK":END 'iiiiiiiMimir To sense the status of the input register, PB, use the same ap- proach as in lines 40 and 50. For example, to sense the status of PB5{J2-14): 60 X= INP(B): X = X AND 8 : PRINT "PB5 isT; 70 IF X = THEN PRINT "Low" 80 IF X = 8 THEN PRINT "High" The value 8 is the decimal number associated with PBS. ANDing the result of the input (INP) isolates its value from the other PB bits. The value 8 is called a "mask." Mask values for bits through 7, respectively, are 1, 2. 4. 8, 16, 32. 64, 128. Combining ideas, we can create a small test program to tell us whether the tester is working at the selected address. Refer to Listing 1. It's important to remember that outputs remain constant until you change them — in other words, outputs are latched. In- puts, on the other hand, are not latched. The value returned is what exists at the instant you Build this low-cost (under $100) PC-based IC tester! JAMES J. BARBARELLO sense it. If a signal changes a short time before you sense it, you would not see the change. If you want to check for a change in input, you can create a loop that continually senses until a change occurs, or until the program has gone through the loop a specified number of times. For example, the fragment in Listing 2 checks input status on PBS until it finds a high or has looped 500 times. 53 g z O IT H O o D < 1A V„D- 1B AB ■ 1Y CD4Q11 :.>■■ 4Y ■ 2B 3Y ■ 2A 3B- v ss 3A - 2A 20 ■)A •IB 2Y 4V INPUTS OUTPUT A e Y l ! l 1 t 1 1 RG. 1— IC SPECIFICATIONS. It takes a pi- nout (a), functional diagram (b), and a truth table (c) to fully specify an IC. Components C1— 0.1 nF, Mylar IC1— 6255 PPI IC2— 74LS138 3'8 decoder J1— DB-25 female D connector, chassis mount J2— DB-25 female D connector, right-an- gle PC mount S1 — 8-position DIP switch S01— 16-pin ZIF socket Miscellaneous: 16-pin and 40-pin low- profile IC sockets, solderless bread- board, case, DB-25 male/male 10-foot cable, PC proto card, wire, solder, etc. Note: The following items are available from JJ Barbarello, RD3, Box 241H, Tennent Road, Manalapan, NJ 07726; Double Sided I/O PC Board (PCtO), $20.00; Complete kit with all parts (no programs or libraries), $85.00; Programs on SW or 3'A" PC disk, $10.00; Program and libraries on 5W or 3V4" PC disk, $35.00; Com- plete Kit with all parts, programs, and libraries, $99.95. Programs in- clude both BASIC and compiled ver- sions of CHNGADR, ICSETUP, IC, and ICAUTO. Libraries include both .DEF and .DAT files for the most common TTL (74xx series) and CMOS (4xxx series) IC's. NJ resi- dents must add 7% sales tax. PC IC PROGRAMMING SHEET IC TYPE: CD 4011 CMOS Quail 2- In NASD Gate Sheet _J of 1 REMARKS: Inputs=1 . 2 .5.6.8 . 9, 1 2. 1 3, 0utputs=3.4. 10. 1 1 , INTERCONNECTS (From ICSETUP Program): IC: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 J1: 1 2 9 10 3 4 23 H/A N/A 5 6 11 12 7 6 25 STEP No. 10 11 12 13 14 15 16 IC PINS Ki Lo Lo Lo Lc Lo Lo Lo Lo H l !.o Lo Lo Lo Lo Lo 10 Lo Lo Lo Lo Hi Lo Lo 15 Lo Lo Lo Lo Lo Lo Hi Lo Lo 1 12 13 14 15 16 NOTES Init. X= Don't Care End Init Test Hi.Lo are outputs FIG. 2— PROGRAMMING SHEET. Create a test program using a form like this for each IC you wish to test. Tester programs Four programs control the test- er: CHNGADR, ICSETUP IC, and ICAUTO. Starting with the sim- plest, CHNGADR is a short pro- gram that reads the file HWAD- DRES.DAT. displays it on the screen, and then asks you for a new hardware address. It stores your answer in a four-character data file ( three characters for the value of the address, and a trail- ing "D" to indicate that the ad- dress is in decimal). ICSETUP allows you to identify the number of pins on the IC un- der test, specify each pin as an input, output, ground, or +V. and label each pin. Then ICS- ETUP counts the number of in- puts and outputs to determine the 8255's mode (PA = ln, PB = Out, PC = In; or PA = Out. PB = In, PC = Out). Then ICS- ETUP assigns the available input and output lines to appropriate pins on the ZIF in the test fixture, and displays an interconnect list, like that shown in Table 1, which specifies which connections from the solderless breadboard go to which ZIF pins. The program then writes your definitions and the 8255 setup information to a definition file. For example, if you specify file "4011," ICSETUP creates a file named 4011. DEF You have to run ICSETUP only once for each type of IC; a library of definitions for common IC's is available from the author. The program called IC uses the definition-file information to al- low you to perform manual test- ing. You use the manual pro- cedure to create a test file that ICAUTO can use to do all testing 54 FIG. 3— THE I/O BOARD CONTAINS only two active components, an 8255 and a 74LS13B. A bypass capacitor and a DIP switch round out the circuitry. automatically. IC asks you tor the name of the file, retrieves the defi- nition information, displays an interconnect list, and then dis- plays a graphical view of the IC under test. Using the interconnect list, you make the connections and then insert the IC to be tested into the ZIF socket. Next you en- ter a pin number and a value (0 or 1). {For IC's that require a clock signal, you can specify a pulse by typing P instead of or 1. A pulse reverses the state of a signal mo- mentarily and then returns it to the original value. Only the IC's response at the end of the pulse will be stored as relevant.) The program outputs the specified value to the specified pin, reads the IC's outputs, saves the re- sults, and displays the states of all pins on the screen. Actually, the IC program has two phases. Initialize and Test. During Initialize, all outputs are stored as "256," which indicates that the results are not to be con- sidered in determining whether an IC is good or bad. When you finish initialization, you select the Test phase. Now both inputs and outputs are stored as they occur. When you finish the Test phase, you select End, at which point you can save the complete test procedure, along with the ac- ceptable results, to a data file if you so desire. Examples of the data structure for the DEF and DAT files are shown in Tables 2 and 3, respectively. The final program, ICAUTO, uses the DEF and DAT files to test an IC automatically. If a response is not what is specified in the DAT file, the program stops, indicates a failure, and identifies the pin where the failure occurred. Oth- erwise, after completing all the sequences in the DAT file, ICA- UTO indicates Pass and requests the next IC. Construction The tester hardware consists of two major components: the PC- based I/O board and the test fix- ture. The two communicate via a standard ribbon cable with 25- pin male D connectors at both ends. We'll begin with the I/O Board, which can be built with a pro- totyping PC "half-card," such as Jameco's JE417. This type of card contains an array of plated- through holes on a 0.1" grid, a mounting area for a DB-25 con- nector, and an edge-contact area suitable for an 8-bit PC expan- sion slot. Before beginning as- sembly, place the card in front of you with the DB-25 mounting area to your left, and the edge- contact area down. Note the 31 gold-plated edge contacts: the c 5 m to 55 w O z o I .— o o n < LT FIG. 4 — THE TEST FIXTURE includes two solderless breadboards. One has permanent connections from J1 ; the ZIF socket is inserted into the other. The software specifies how the two must be interconnected, depending on the type of 1C to be tested. LISTING 1 1 REM** I/OTEST.BAS 10 CLS : PRINT : PRINT : PRINT : DEF SEG = 64 20 INPUT "Address You've Selected (ex: 640)"; A 15 B = A+l: C = B+l: D = C+l 30 OUT D, 130 : REM** PA=0utput, PB= Input, PC=0utput 255 : XI = INP(A) : X2 = INP(A) 40 OUT A, 50 OUT A, 60 IF (XI <> 255) OR (X2 <> 0) THEN PRINT "Problem With PA" 70 OUT C, 255 : XI = INP 255) OR (X2 <> 0) THEN PRINT "Problem With PC" 100 OUT D, 153 : REM** PA=Input, PB=0utput, PC=Input 110 OUT B, 255 : XI = INP(B) 120 OUT B, : X2 = INP{B) 130 IF (XI <> 255) OR (X2 <> 0) THEN PRINT "Problem With PB" 135 GOTO 150 140 PRINT : PRINT TAB(25); "I/O BOARD TESTS OK AT ADDRESS"; A 150 PRINT : PRINT : PRINT : END LISTING 2 200 REM** This code checks for a high input on PBS (J2-14) 210 REM** It assumes you've set up the 8255 by creating 215 REM** variables A,B,C f D and have performed an 220 REM** OUT D, 130 to set PB as an input register. 230 REM 240 IF (INP(B) AND 8)<> 8 THEN X=X+1 : GOTO 260 250 PRINT "High Sensed On PB5." : END 260 IF X < 500 THEN GOTO 240 : REM** Try 500 times. 270 PRINT "PB5 Remained Low During 500 Sensings." : END left-most one is BI. Find contacts B5 through B10. and, using a hobby knife, remove them. Doing so is a safety measure to ensure that the + 12, -12, and -5-voIt supplies from the PC do not get into our + 5-volt-only circuitry. Next, flip the card over so that the DB-25 area is to your right. Install a low-profile 40-pin socket vertically about an inch from the DB-25 mounting area, as shown in the opening photos of this arti- cle, and solder it in place. Locate a 16-pin low-profile socket hori- zontally about an inch above the edge contacts; the left end of the socket should be above edge-con- tact A31. Solder the socket to the board. Then mount SI horizon- tally above the 16-pin socket and solder in place. Using 22-gauge wire or smaller, make all interconnections, as shown in Fig. 2. Check for shorts, opens, and solder bridges. Then mount the DB-25 connector. Now insert IC1 and IC2 into their sockets, and check the board once more. Set one (and oniy one!) element of SI on, according to the addresses shown in Table 4. If you're not sure which address to use, try ad- dress 544 for a standard PC, or 640 for an AT or 386). Next, power down your computer, in- sert the card in a free slot, and power back up. Never fiddle with the board while the PC is on. Enter and run I/OTEST.BAS (shown in Listing 1) using GWBASIC or BASICA. Be sure to enter the correct address when the program prompts you, Ifyou get the message "I/O BOARD TESTS OK AT ADDRESS XXX" (where "XXX" is the address you specified with SI), you're ready to proceed. Otherwise, power down the PC, set SI to another address, and try again. The test fixture consists of a plastic box (any size or type will do), a DB-25 female connector, two chunks of a solderless bread- board, and a 16-pin ZIF socket for test ICs. See the opening photos of this article. The solderless breadboard should have at least 42 rows of contacts and no power buses. Starting from one end, count down 26 rows and carefully cut the breadboard with a fine-tooth hack saw. File the end of the piece you just cut so that you end up 56 with a piece with 25 clean rows of contacts. Typical breadboards have two unconnected columns of con- tacts separated by a "valley. " Cut along the valley to create a piece with just a single column of 25 rows of five contacts. This is the block into which the 24 wires from Jl will be inserted. From the remaining piece (with the valley), cut a section that contains 22 rows. Do not cut down the valley, because this piece will accept the ZIF socket. File the ends smooth. Now machine the box to accept Jl and the breadboards, and drill some holes on top to pass the Jl wires. Solder 6" lengths of #22 solid wire to Jl pins 1 through 23, and pin 25. Mount Jl in the box. Locate the Jl connecting block (the one without the valley) on the box and secure It with glue or double-sided tape. Beginning with pin 1, feed each wire up through the hole and insert in row 1. Continue through pin 23. Last, feed the wire from Jl. pin 25 and insert it in row 25. Note: Nothing is connected to row 24. Check continuity between J 1 and the block to ensure you've con- nected all the leads correctly. Lo- cate the other block (with the valley) perpendicular to the Jl block and secure it to the box. Insert the ZIF into the block. Mark the block to indicate which row is pin 1. which is pin 2, etc. Cut sixteen 6" lengths of #22 sol- id wire and strip %" of insulation from each end of each wire. These will serve to connect the Jl block to the ZIF block. Use At this point you should have a board [with verified address) and a HWADDRES.DAT file indicat- ing that address. You should also have a correctly-wired test fix- ture, and a cable to connect it to the board. To create a data file for an IC, run ICSETUP. Identify the IC as either 14 or 16 pins. Then define each pin as an output or an in- put, and give each pin a name (six-character maximum length). Don't define the power pins yet. When finished, enter "99." Now you'll be asked to identify the GND and +V pins. When you're done, you'll be asked if you want to save this definition to a file. TABLE 1 SAMPLE INTERCONNECT LIST S01 /ZIF Socket J 1 /Breadboard 1 1 2 2 3 9 4 10 5 3 6 4 7 23 8 9 10 5 11 6 12 11 13 12 14 7 15 8 16 25 TABLE 3—4011 DAT FILE TABLE 2—4011 DEF FILE Rec. Decoded No. Data Mask 1 CD 401 1 , Quad 2 2-ln NAND Gale, 3 CMOS 4 Decoded 5 Mask 6 130 7 OUT1 IN-A A" 1 8 OUT2 IN-A A" 2 9 OUT3 IN-A B** 1 10 OUT4 OUT-A 8" 2 11 OUTS OUT-B A" 4 12 OUT6 IN-B A" 8 13 N/A7 IN-B ** 14 ft* 15 ** 16 OUT 8IN-C A** 16 17 OUT 9IN-C A** 32 18 OUT10OUT-C B" 4 19 OUT110UT-D B" 8 20 OUT12IN-D A" 64 21 OUT13IN-D A" 128 22 N/A14V + ft* ** Note: Encoded mask value Answer yes and enter a descrip- tive name (the number of the IC, maximum eight characters), and don't include an extension. Now get a clean programming sheet and create a test program for that IC. With the program- ming sheet in hand, run IC, Iden- tify the previously specified file name. Connect the Jl and ZIF test blocks according to the inter- connect list that appears on the screen. Insert a known good IC and press a key. Execute the Initialize and Test procedures as outlined above. Rec. No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 'ortA PortB PortC 1 256 3 256 7 256 15 256 31 256 63 256 127 256 255 256 254 1 250 3 234 7 170 15 171 14 175 12 191 8 255 253 1 245 3 213 7 85 15 87 14 95 12 127 8 255 TABLE 4—i/O ADDRESS Switch Pos. Address S1-a 512 S1-b 544 Sl-c 576 Sl-d 608 S1-e 640 Sl-f 672 S1-g 704 S1-h 736 When done, select End, and in response to the Save question, specify Yes. You now have the files necessary to test IC's of this type. To test an IC, run ICAUTO. Specify a file name, connect the test blocks, insert the IC to be tested, and press a key. As the IC is tested, you will hear a short tone as each step is per- formed. The bottom of the screen will report the relevant informa- tion, and the graphical represen- tation of the IC on the screen will show how the inputs and out- puts are changing. If the IC fails, the test will stop and the pin where failure occurred will be highlighted. Otherwise, the test will end and "Pass" will be indi- cated. Insert the next IC to be tested and press any key to con- tinue. After testing all IC's of that type press Esc to end. R-E c 57 /■v/%-^ mJooUri 1 00001 1 1 1 0001 01 001 01 1 1 0001 01 0( 01111000011101011010001110101 0001111 0001011 01 000011101 c 01 01 1 "tfQPtf WW Wf Q1 W 1 c 01 oii|ci(lipifiii o|oi>\il}i 001010111010001 01101 0110010C 001 1 01 01 01 001 1 001 01 000001 1 c 01 01 0001 1 1 0001 C1 01 C0001 110101 1 00001 1 1 U0WUW001 01 1 1 0001 01 0( 01111000011101011010001110101 01 1 0001 1 1 1 0001 01 1 01 00001 1 1 01 c ig 001011 00101 1 «|i|i|T8C|r|roj|i ci oi oli^roloTiJGloTOef^fed 1 001 010111 01 0001 01 1 01 01 1 001 oc 1 1 001 1 01 01 01 001 1 001 01 000001 1 c 01010001110001010100001110101 CONVERTERS Discover the basics of some of the most widely used D/A and A/D conversion techniques. V) o z o cc I- o IJJ _l 111 o q < WE UVE IN A WORLD OF CONTINUALLY varying analog dimensions, whether we're dealing with sight, sound, temperature, voltage, or current. Most physical and elec- trical parameters that we per- ceive change in a continuous manner, taking on an infinite number of values. Although our real-world consists mostly of ana- log signals, they can be difficult to manipulate. Digital signals, on the other hand, can be controlled by simple logic circuits, or by mi- croprocessors. Complex opera- tions can be more easily per- formed by digital rather than analog circuits. When digital cir- cuits need inputs from the ana- log world or must output data to it, digital-to-analog (D/A) and an a log- to -digital (A/D) converters become an essential interface. We will explain some basic techniques of D/A and A/D con- STEPHEN J. BIGELOW version, as well as the important characteristics of certain types of approaches. We'll also show you some simple circuits with inex- pensive, off-the-shelf parts you can easily build yourself. Digital-to-analog converters Digital-to-analog converters (DAC's) translate binary words from computers or other discrete circuitry into proportional ana- log-voltage levels. D/A converters can be used to drive analog de- vices such as meters, motor con- trollers, or audio circuitry. Per- haps the most dramatic example of D/A conversion is in a compact disk (CD) player. A DAC is used to convert the digital data recorded on the CD into the high-fidelity audio signal that you hear. Let's look at important D/A concepts. The resolution of a D/A con- verter is the number of individu- al analog voltage levels that the output is capable of generating. That is directly related to the number of input bits that forms the binary word. A 4-bit DAC has 4 input bits with a resolution of 4. The number of distinct and different analog output levels the IC is capable of generating will be 2" (2 4 ) or 16 levels. That means the analog output can be repre- sented by up to 16 voltage levels. An 8-bit DAC can provide an ana- log output at up to 2 a or 256 dis- crete levels. A 12-bit DAC can represent a digital word in 2 12 or 4096 levels. As you can see, the more bits an A/D converter pro- vides, the more accurately it can generate an analog signal, as shown in Fig, 1, Settling time is the term used for the time required for the ana- 58 log output to stabilize after the binary input changes. It is usu- ally specified as the time taken for the output to stabilize within ± V-2. the least significant bit (LSB) of the expected value after the binary input changes. What that means in practical terms re- lates to the actual value of the LSB itself. If an 8-bit DAC has a to 10-voU output range, then the LSB is worth '%» or 0.039 volts. Half of that value is 0.0195 volts. The settling time would be the time required for the output to reach 0.0195 volts of the expected value. Settling time is typically under 10 \is. Accuracy is another important factor in D/A converters. In sim- plest terms, the accuracy of a DAC is usually specified as ± anywhere from '/i to 2 times the LSB. Let's consider that more closely. For a DAC with an ac- curacy of ± one times the LSB, the voltage output can vary by as much as + or - the value of one bit. If the DAC has a 0- to 5-volt output with 12 bits of resolution, the LSB would be 5 /a 12 or 0.00122 volts. For any binary input, the output voltage may be higher or lower than the expected value by 0.00122 volts. If that same DAC has ± Vi times the LSB accuracy, an output could only deviate ± o °° ,2 % or ± 0.00061 volts. The smaller an accuracy value is, the more closely the output will match the expected output. Several methods have been de- veloped over the years to deal with digital-to-analog con- version. We will look at two gener- ally accepted methods: binary weighted and binary ladder D/A. Binary-weighted resistor D/A The binary-weighted tech- nique is the oldest and simplest method of converting digital bits into an analog signal. For the cir- cuit in Fig. 2, a binary word is applied to a series of gates that drive analog switches. When a binary 0000 is applied to the gates, all analog switches are open so no voltage is applied to the op-amp. The output is then volts. When a binary 0001 is applied. SI closes and - 10 volts is applied to Rl. Since the op- amp input represents a virtual ground, there is effectively 10 volts across the 8K resistor. That causes 10 V/8000 H. or FIG. 1— FINER RESOLUTION OF THE OUTPUT VOLTAGE in a DAC is provided by using a larger number of bits. FIG. 2— A BINARY WEIGHTED D/A converter offers a simple example of basic DAC operation. 1.25 mA, to flow through the 800-ohm feedback resistor, R P By Ohm's law. the voltage across R" F would be 800 ohms x 1.25 mA, or 1 volt. When the binary word changes to 0010. SI opens and S2 closes. That causes 2.5 mA (10 V/4000 £1) to flow through R2. The voltage across R F is then 800 ohms x 2.5 mA, or 2 volts. A binary 0100 would re- sult in 4 volts at the output, and a binary 1000 would cause 8 59 BINARY INPUT WORD FIG. 3— A-BINARY LADDER provides a simple, reliable, and accurate method of D/A conversion. 111- 110- 101 ■ 100- 011- 010- 001 ooo WILED BIT \ 101- 100- 101 too 001 000 001 000 sis NON-MON0TONIC DAC w o z o cc F o LU G < FIG. 4— A MONOTONIC DAC will reach every analog step correctly for each dig- ital input word. volts at the output. Notice how the value of input and feedback resistors are carefully chosen to create a binary progression. Each switch can be closed in combination to generate an analog output from to 15 volts (0000 = V, 0111 = 7 V, and 1111 = 15 V) in 1 volt incre- ments. Although a binary- weigh ted resistor DAC is straightfor- ward, it's not practical for ap- plications requiring much more than 4 bits of resolution since the range of resistor val- ues required would be tremen- dous. A ladder network needs only two values of resistance. Ladder network D/A The ladder-network technique is capable of producing binary weighted voltages with only two values of resistance arranged in a type of voltage-divider network known as a binary ladder, shown in Fig. 3. Although that circuit may appear intimidating at first glance, the ladder operates in much the same way as Fig. 2. A series of gates are used to drive analog switches. When a binary 0000 is sent to the gates, all ana- log switches are open so there is a O-V output from the op-amp. A binary 1000 will activate the most significant bit (MSB). That closes SI resulting in 5 volts at the output. An input of 0100 will close S2 and yield 2.5 volts at the output. A binary sig- nal of 0010 will close S3 and place 1.25 volts at the output. And finally, an input of 0001 will close S4 to produce 0.0625 volts at the output. Notice that each output is in a binary pro- gression. That allows the out- put to vary from to 10 volts in 0.625-volt increments (24 or 16 steps). The primary advantage of the binary ladder design (and the reason for its tremendous pop- ularity) is its use of only two resistor values. As a result, it is a very simple matter to add vir- tually any number of bits sim- ply by adding additional re- sistor "rungs" to the ladder. The binary ladder has proven so successful that it can be found as the key segment of almost every DAC manufactured today. Binary ladders also tend to be more accurate than binary weighted circuits since it's much easier to find precision resistors in two values (such as 10K and 20K) than the many diverse values that would be re- TERMS AND DEFINITIONS • Accuracy — A figure indicating how closely the converter's output represents the input information, usually expressed as a portion of the LSB. • Binary Coded Decimal (BCD)— A binary numbering system using binary codes through 9 only, in- stead of through E That allows a closer relationship between dig- ital data and decimal numbers. • Comparator— -An op-amp circuit used in ADC's to compare the ana- log input signal to a reference volt- age. • Conversion Time — An ADC term used to indicate the amount of time required for the analog in- put voltage to be converted to a digital word. • Integrator — An op-amp circuit used in some ADC's to provide stable voltage-ramp performance for slope conversion. • Least Significant Bit (LSB) — A digital bit which carries the least binary weight in the digital word. • Monotonicity — A DAC term used to indicate that each analog output step will be correct for every corresponding digital input word. • Most Significant Bit (MSB)— A digital bit which carries the great- est binary weight in a digital word. • Quantizing Error— Error intro- duced into an A/D conversion when the analog input changes during the conversion cycle. The amount of error depends on the rate of signal change and the con- version time. • Resolution — The number of dis- crete digital states (usually ex- pressed as 2 n bits) that are used to express an analog signal. » Settling Time— A DAC term used to express the amount of time required for the analog out- put to stabilize after the digital in- put has changed, quired in a binary weighted cir- cuit. Conventional D/A convert- ers integrate resistors and am- plifiers onto a single 1C, such as Precision Monolithic's DAC-08. Now that we've discussed the basic approaches of DAC opera- tion, we can examine a final im- portant specification of monot- onicity. As you know, the analog output voltage of a DAC will pro- gress in steps as the binary in- put word increments, as shown in Fig. 4. Ideally, each incre- ment in the binary input will cause a known, predictable step in the output voltage. In some devices, however, the switching and amplifier components do 60 not allow enough current to flow under all conditions. That can cause the DAC to "skip" steps at certain bit levels. While a monotonicity problem on a low-weight bit may have little impact on the output, the effects become more significant as the weight of the bit in- creases. A DAC is said to be mo- notonic if it does not miss any steps across the entire range of binary inputs. Now lets look at more involved A/D converters. Analog-to-digital converters An analog- to-digital converter (ADC) is used to translate a con- tinuous analog signal into a finite number of digital bits. The resulting digital "word" becomes the binary representation of the analog level at the moment it was converted. The resolution of an ADC is very much like its DAC counter- part — it is the number of bits with which the ADC will repre- sent the analog signal. An ADC with 4 bits will have a resolution of 4 bits, and can represent an analog signal with up to 2 4 or 16 binary words. An 8-bit ADC can represent an analog signal with up to 2 8 or 256 discrete words. A 12-bit ADC can represent. an ana- log signal with as many as 2 12 or 4096 individual binary words. You probably get the picture. The more bits of resolution by now an A/D converter can provide, the more accurately it will represent the analog signal, as shown in Fig. 5. Conversion time is another im- portant aspect of A/D converters. As you will see, the conversion of an analog signal into a digital word is not an event, but a pre- cise, deliberate process. As a re- sult, it requires some finite amount of time to sample the analog input, digitize it, then make the binary result available at the output. The conversion time is the period of time re- quired to complete that process. It can range anywhere from mi- croseconds (for very fast convert- ers) to milliseconds (for slower devices). Since A/D conversion is a precise synchronized process, a clock source is also needed in most devices. Sampling theory Since an ADC requires a cer- Jl -\ ADC ANALOG INPUT SIGNAL 2-BIT RESOLUTION CLOCK V k DIGITAL ,0 OUTPUT 01- 00 2 N OR 4 LEVELS DIGITAL REPRESENTATION -»- t n ADC ANALOG INPUT SIGNAL 4-BIT RESOLUTION CLOCK 2 N OR 16 LEVELS DIGITAL REPRESENTATION FIG. 5— THE RESOLUTION OF A/D CONVERTERS is directly affected by the number of bits. Vim +V ci A V IN ■'•"CC a SAMPLE flECONSTniJCTELI POINTS SIGNAL FIG. 6— THE MORE SAMPLE POINTS taken from an analog signal, the more closely a reconstructed signal will resem- ble the original. tain amount of time to perform a conversion, there are only just so many samples of a signal a con- verter can digitize in any given time. For example, if an ADC makes one conversion in 1 ms, it could then theoretically make 1000 conversions in 1 second (1/.001 s). The maximum con- version rate is equal to the re- ciprocal of the conversion time. lb digitize a faithful represen- tation of the analog input, the converter takes samples at a min- imum of twice the maximum fre- quency component of the analog input signal. That sampling rate is also known as the Nyquist rate. Consider an analog sine wave of 10 Hz applied to an ideal ADC in R4 MSB LOGICAL GATING NETWORK % °i V|* BINARY OUTPUT COMPARATOR OUTPUT D, Dc MSB MB LSB 0-2V 2-4V 1 1 4-6V 1 1 1 6-8V 1 I 1 1 1 FIG. 7— THE FLASH A/D CONVERTER of- fers speed and simplicity of operation at low resolutions. Fig. 6. The minimum sampling rate is If, or 20 Hz, which yields two digital-data points for each cycle. When the digital data is reconstructed by a DAC, the new analog signal bears a re- semblance to the original. (A fil- ter on the DAC output smooths c ID CO 61 COMPARATOR CLOCK Jl -_D^ REFERENCE VOLTAGE TIMING AND VOLTAGE RAMP CIRCUIT COUNTER OUTPUT LATCH OUTPUT BINARY WORD FIG. 8— A RAMP GENERATOR, COMPARATOR, AND COUNTER are the key components of a single-slope A/D converter. "Integrator TIMING AND CONTROL CIRCUIT OUTPUT LATCHES BINARY OUTPUT FIXED INPUT TIME- - 1| *| HIGH INPUT O LU _J LU O D < FIG. 9— A DUAL-SLOPE A/D CONVERTER provides much more stable operation than the single-slope converter. the sharp peaks of the recon- structed signal.) If 10 Hz is the maximum frequency entering the ADC, the maximum allowa- ble conversion time is 1/20 Hz, or 500 ms. If the maximum Input frequency is raised to 10 kHz, the ADC needs to sample at 2£ or 20 kHz to maintain the same two data points per cycle. That means the converter has to perform con- versions in 1/20,000 Hz, or 500 (jls just to keep up with the input signal. To improve the fidelity of the digitized signal, we could take more samples in the same period of time. A sample rate of 8 points per cycie requires a sample rate of 8 times the maximLim frequency component of the input signal. An input of 10 Hz must be sampled at 80 Hz, so the convert- er would have to convert a point in 1/80 Hz or 12.5 ms. A 100-kHz signal needs to be sampled at 800 kHz, The ADC then converts a sample in 1/800,000 Hz, or 1.25 (as. That is extremely fast for most A/D converters, although there are some types which can approach 1-(jls conversion times. If the ADC cannot sample fast enough to keep up with the sig- nal, information contained in the analog input signal will be lost. The relationship between in- put frequency, conversion time, and sample rate is a very impor- tant one. A variety of methods have been developed over the years to perform the digitizing of analog signals. Many are still in use today in one form or another. We will examine six of those tech- niques: flash, single slope, dou- ble slope, single counter, track- ing counter, and successive approximation. Flash conversion The flash converter is the fast- est type of A/D converter that is available (Fig. 7). It uses a bank of parallel comparators to process the analog input. Flash convert- ers are also referred to as parallel converters. A series of resistors form a voltage-divider network across each comparator. The maximum input voltage that can be translated depends on the val- ue of V cc . The output signal from each comparator is either on or off, and is compatible with digital logic. With no input voltage, the out- put of each comparator is logic low. As the input voltage in- creases, the output of each com- parator will cascade high as the input exceeds each reference 62 voltage set by the voltage-divider network. A network of digital gates is used to convert the array of comparator signals into a bin- ary word which is made available at the converters output. Our example in Fig. 7 provides only two bits of resolution. A 2- bit ADC is not very practical for most applications, but it demon- strates the key concepts needed to build a flash converter. As you may have noticed from the cir- cuit in Fig. 7, if takes 2"~ ] com- parators to support the resolu- tion of the converter. Our 2-bit ADC example requires 2 2 - 1 , or 3 comparators: a 4-bit converter needs 2 4 — 1, or 15 comparators; an 8-bit flash ADC needs 2«-l, or 255 comparators, and so on. This vastly increasing complexity is a great disadvantage in flash devices — not only in the need for additional comparators, but also in the unwieldy gating circuitry as well. The main advantage to flash converters, of course, is simple speed. Since the analog input is applied to every comparator si- multaneously, the conversion time is merely equal to the propa- gation delay of the comparators and gating circuitry. A flash con- version can be accomplished in just a few microseconds. Single-slope ADC A more efficient method of A/D conversion is the single-slope A/ D, also known as the single-ramp A/D (Fig. 8). In the single-slope circuit, the cycle begins with the counter reset and the ramp volt- age at zero. The comparators output at that point is low, so no clock signals are allowed to reach the counter. When an input volt- age is applied to the converter, the comparator's noninverting input ( + ) will exceed the voltage at the inverting ( - ) input, so it's output will be high. That will en- able the and gate, which will allow clock pulses to reach the binary counter. At the same time, a tim- ing circuit drives the voltage ramp up, which quickly in- creases the reference voltage on the comparators inverting in- put. When the reference- ramp voltage just exceeds the input voltage, the comparators output falls low again. The clock pulses stop and the timing circuit latches the count at the binary CLOCK _TL IC2 TIMING AND CONTROL CIRCUITS \7. BINARY COUNTER D/A CONVERTER BINARY LATCH BINARY OUTPUT REFERENCE t VOLTAGF FIG. TO— A D/A CONVERTER can be used to provide the voltage ramp needed to operate a single-counter A/D converter. counter and resets the counter for the next conversion. The single-ramp circuit is little more than a controlled counter with a voltage-feedback loop. The circuit is timed in such a way that when the reference-ramp voltage equals the applied input voltage, the binary count exist- ing on the counter at that mo- ment is the digitized value of the analog signal. Note that the speed of the clock and the rate of the voltage ramp must both be set correctly for the counter to function properly. The time required to perform a conversion will depend upon the level of the analog input. Since the counter and reference ramp both start from zero at each con- version, it will take longer to match a higher level of analog in- put than a low level. The se- quence of operations can take place very quickly. The reference- ramp voltage can change faster than 1 volt per ms to reach the input voltage. For example, if an input of 2 volts is applied to the circuit in Fig. 8, it would take 2x1 volt/ms, which equals 2 ms for the ramp voltage to equal the input. The actual binary count after 2 ms depends on the speed of the clock. A faster clock speed will yield a higher count, and vice versa. Since the clock can operate in- dependent of the voltage ramp. unique opportunities for other outputs besides straight binary become available. Some customized instrument IC's use single-slope techniques to con- vert an analog input directly to binary coded decimal (BCD) to drive 7-segment displays. That type of flexibility is a strong ad- vantage. The primary disadvan- tage of using single-slope tech- niques is the tendency toward unstable operation over time. Without some form of syn- chronization between the clock and ramp generator, any drift in clock speed or ramp voltage per- formance will cause errors in the output word. That's why single- slope converters are not used in high precision applications. Dual-slope ADC The dual-slope conversion technique offers the advantage of conversion stability at the ex- pense of conversion speed. The reference-ramp generator circuit eliminates the effects of compo- nent drift over time (Fig. 9). The input signal of a dual-slope converter is fed into an inte- grator. When a positive input sig- nal is applied, the integrator's output voltage ramps in the negative direction. The negative voltage forces the output of the ^ comparator high. That in turn r< activates the clock input to the ^ counterwhich will begin to incre- 'S. 63 o EC H o LU — I LU 6 Q < CLOCK Jl IC1 IC2 IC3 TIMING AND CONTROL CIRCUITS FEEDBACK SIGNAL D U BINARY U/D COUNTER D/A CONVERTER BINARY LATCH FIG. 11— A BINARY UP/DOWN COUNTER enables the A/D converter to track changes in the analog input for the tracking-counter A/D. ment. The integrator will ramp for only a fixed period of time. After that fixed "input-time," the control circuit clears the counter and switches the converter's in- put to a fixed negative-reference voltage ( -VjtEp). With a negative voltage now applied to the inte- grator, its output ramps back in the positive direction. The coun- ter begins a new series of counts until the integrator's output reaches zero. At that point, the comparator's output becomes low. That action shuts off the clock pulses to the counter. Con- trol circuitry detects that change and latches the count to the out- put, then clears the counter. As with the single-slope converter, the final digital count represents the analog-input voltage. The rate of integration depends on the magnitude of the input voltage, as well as the value of Rl and C 1 , so a low input voltage will reduce the integrators output less than a high input voltage during the same fixed-input period of the conversion cycle. When a fixed negative reference voltage is applied (the values of Rl and CI remaining constant), the time required for the inte- grator to return to zero is then directly proportional to the origi- nal magnitude of the input volt- age. Any variations, therefore, in the integrator circuit due to time or temperature will automatically be canceled out. That allows the dual-slope converter much more stability for high-precision ap- plications. Similar to the single- slope technique, dual-slope con- verters can be used to convert the input signal directly to BCD (or any other viable code) as well as regular binary. Most quality dig- ital voltmeters use dual-slope conversion to translate the input directly to BCD. The disadvantage of dual-slope conversion is the extended period of time needed to make a conversion. A dual-slope convert- er may require more than 100 ms to translate a high input voltage. D/A feedback converters D/A converters may also be used to provide the reference feedback signal to the com- parator. There are two basic types that we will examine: single- counter and tracking-counter types. Let's take a brief look at each one. The single-counter A/D con- verter is a variation of the single- slope approach. Its operation is identical in all aspects but one — a D/A converter is used to read the count from the binary coun- ter and provide a feedback volt- age to the comparator instead of an integrator or other voltage- ramp source (Fig. 10). When an analog input is ap- plied to the comparator, its out- put becomes high. That allows clock signals to reach a binary counter. As the counter incre- ments, the voltage output of the DAC increases at the negative in- put to the comparator. When the DAC level just exceeds the input, the comparator shuts down. A control circuit latches the binary count to the output, as well as resets the counter for the next conversion. Although single-counter con- version is a faster method than the dual- ramp approach, it does require the use of a high-preci- sion DAC to provide a steady, accurate feedback signal to the comparator. It also requires the counter to start from zero at each conversion. That can waste a bit of time through each cycle, es- pecially if the voltages to be con- verted are near their maximum levels. The tracking-counter tech- nique can yield conversions much faster than the single- counter. That is possible by "the use of a binary up/down (U/D) counter instead of just an up counter like the ones used in our previous examples. The counter can increment or decrement de- pending on the state of the com- parator's output. That permits the binary word to literally track the changes in the analog signal (Fig. 11). The cycle begins with an ana- log signal to the comparator. The count on the binary U/D counter may be at any value. That means that the DAC feedback voltage may be greater or less than the analog input. If the feedback volt- age is greater than the analog in- put, the comparator's outputwill be low and the control circuits will gate the clock pulses to the count-down input of the counter. That will decrement the binary counter's output and reduce the feedback voltage at the com- parator. When feedback voltage drops below the analog input, the comparator's output will go high and control circuits will cause the binary count to latch to the output. Gating will send clock signals to the up input of the counter (which is not reset) and cause it to begin counting up 64 CLOCK LSB START OF CONVERSION (SOC) SUCCESSIVE APPROXIMATE REGISTER FEEDBACK VOLTAGE SB END OF CONVERSION (EOC) 1 D/A CONVERTER Oinpi.fr LATCH BINARY OUTPUT FIG. 12— A SUCCESSIVE APPROXIMATION REGISTER " i 1/ /\ 1 S i A V ERROR ^L ! START i ;end i ■ ■ CONVERSION FIG. 13— QUANTIZING ERROR can enter the A/D conversion as the analog signal changes during the conversion cycle. No quantizing error exists for a DC voltage (a) because there is no change in voltage, some quantizing error occurs with low- frequency signals (b), and a higher degree of quantizing error is produced with high- frequency signals (c>. again looking for another change of state. If the input signal re- mains constant, the output word will tend to oscillate by 1 x LSB as the converter tries to center it- self. That potential oscillation problem is the greatest disadvan- tage of tracking-counter ADC's. As you might imagine, this type of converter can be much faster than the single-counter technique, but it is best suited for digitizing fast-changing ana- log inputs. Signals which change quickly are less likely to allow the converter to oscillate. Successive-approximation ADC Of all the techniques that we have covered up to now, the suc- cessive approximation (SA) ap- proach has become the tech- nique of choice for low-cost, moderate-resolution, high-speed A/D converters. Successive ap- proximation is a clever and powerful technique that can be used to digitize an analog signal quickly and efficiently with no os- ANALOG SWITCH -L-O I S1 I CM 1 CLOCK SOURCE dilation. The process of con- version is a bit more involved than the counter techniques that we have discussed. The heart of the SA converter is a device called the successive ap- proximation register (SAR), This serves a very different purpose than the counters we have seen (Fig. 12). The conversion cycle begins when an analog signal is applied to the converter and a start con- version pulse is placed on the SAR. The first clock pulse into the SAR turns on the MSB out- put. That in turn sets the DAC output to 50% of its voltage out- put. The SAR looks at the com- parator's output to see if the DAC output is greater or less than the analog input. If the DAC voltage is greater, the comparator will be off, so the SAR will turn off the MSB and call it a zero. If the DAC voltage is less than the analog in- put, the comparator will remain on, so the SAR will leave the MSB on and call it a one. It does all of this in one clock pulse. On the next clock pulse, the SAR will turn on the second most signifi- cant bit and re-check the results from the comparator. Once again, if the new DAC signal is greater than the input voltage, the comparator output will be off, so the SAR will turn off the bit and call it zero. If the new DAC signal is less, the comparator will remain on, and the SAR will leave the bit on as a one. The SAR will examine each bit in this fashion (MSB to LSB) un- til all bits have been examined. Since one bit is evaluated in one clock pulse, an 8-bit ADC will process the conversion in only 8 clock pulses. When the LSB is fi- nally processed, the SAR will send out an end of conversion (EOC) signal which will latch the SsCl c 5 quantizing error. 65 CO o o p o < resulting binary word directly to the output. Successive approximation converters are perhaps the most efficient type of A/D converters available. They are capable of ex- tremely fast conversions at high resolutions. Many converters of this type can process 12 bits of resolution in less than 10 m-s- Quantizing error Now that you have a better idea of how A/D converters operate, we will discuss the characteristic of quantizing error. Quantizing er- ror is caused by changes in the analog-input level during the conversion process. Remember that the analog sig- nal of an ADC is applied to a com- parator. When a cycle is started, it requires some finite amount of time (microseconds to millise- conds) to produce a digital out- put. If the input voltage changes during the conversion, the final binary output will represent the voltage level at the end of the cycle instead of the beginning. When there is no change in input volt- age, such as in a DC voltage, no quantizing error enters into the conversion, as shown in Fig. 13- a. The faster the signal change, or "slew rate," the greater the quantizing error will be (Figs. 13- b, 13-c). One common way of avoiding quantizing error is to use a sam- ple and hold circuit before the analog input to the comparator. Figure 14 shows such a circuit. An electronic switch is closed to take a rapid sample of the analog input signal. The sample capaci- tor CI charges to the value of the input signal and the electronic switch will open. That eliminates the effects of quantizing error since the capacitor will retain the value of the analog sample re- gardless of how the overall analog signal may be changing. When it is time for another conversion, the circuit will take another sam- ple. Now lets take a look at some actual circuit applications. Basic D/A application Figure 15 shows a simple D/A converter application using a Motorola MCI 408 DAC. The oper- ation of the circuit is very straightforward. A TTL-level 8- bit binary word is applied to the DAC inputs D through D 7 . BINARY DATA < INPUT 13 LCI MC14QB *LSB ^ CI 55pF 14 1% i + 15V 1 :.'v is ^ R1 5V MSB LSB | V ou t n 11 1 1 1 I ' ! 1 5V [ 1 1 1 1 I I 1 1 | 10V (Q f {2 4 8 16 32 64 128 256 FIG. 15— A UNIPOLAR D/A application circuit. Art 8-bit binary word is applied to the DAC Input. A binary ladder is used in the MC1408 to translate the signal Into a current output, an op-amp Is then used to convert the current Into a voltage signal. C1 15pF 15V MS8 LSB \ur 1! -10V I 1 I 1 1 1 1 ov 1 1 1 1 1 1 1 1 + 10V v dut-j-ri" I z 4 8 16 32 64 128 256)/ L R2 FIG. 16— IN A BIPOLAR D/A application circuit the output can vary from a negative to a positive voltage. Since no clock or outside timing is required, the conversion takes only the settle time of the MC1408 (about 300 ns). The MCI 408 uses a binary ladder to switch and translate the signal into a current output. An op- amp, such as the LM741, can be used to convert the current sig- nal into voltage. The resolution of that circuit is 8 bits, which means that the ana- log output can vary from to 10 volts through 2 8 or 256 individu- al steps. A binary word of OOh (hexadecimal) causes an output of volts. A half-scale input of 7Fh generates 5 volts at the out- put. A full-scale input of FFh causes 10 volts at the output. That circuit can easily be used just about anywhere a basic DAC is needed to interface a digital signal to an analog circuit. The digital word may be provided from a conventional computer port, a digital counter, or any other discrete TTL circuit. The analog output may be con- ditioned to drive meters, indica- tors, amplifiers, or other analog circuits. Bipolar D/A application The previous example shown in Fig, 15 showed a unipolar cir- cuit, meaning that the output is only in one polarity. If a bipolar output is needed {one that varies from a negative to a positive volt- age) the circuit can be changed as shown in Fig. 16. Connecting the input of the op- amp to the reference resistor R2 66 TABLE 1— POPULAR 8-BIT CONVERTERS Component Type Description Resolution Conversion Time Settling Time Supply Voltages Price* MC14433P A/D Dual Slope 3Vi Digits 40ms — + 5, +8 $7.00 MC14443P A'D Single Slope 8 bits 300ms — + 5, +8 $4.00 MC14447P A/D Single Slope 8 bits 300ms — -5, t8 $4.00 MC14559BCP A/D Successive Approximation 8 bits — — ±3 to ±18 $7.00 ADC0803 A/D Successive Approximation ± Vz LSB 8 bits 100|AS — + 5V $5.00 ADC0808 A/D Successive Approximation ± 'A LSB 8 bits 1QO|xs — + 5V $5.00 ADC0809 A/D Successive Approximation ±1 LSB 8 bits lOOjiLS — + 5V $4.00 Successive Approximation i-1 I GJR Ifi-Phannel ADC081 7 A/D Multiplexer 8 bits 100 (is — + 5V $8.00 ADC0820 A/D Flash Conversion Track/Hold Function 1.18(j,s — + 5V $8.50 MC1408P8 D/A Multiplying 8 bits — 300ns + 5, -15 $1.50 MC1408 D/A Multiplying 8 bits — 300ns + 5, -5 to -15 $1.50 DAC08 D/A High-Speed 8 bits — 150ns ±4.5to±18 $3.00 DAC0800 D/A High-Speed Current Output 3 bits — 100ns ±4.5to±18 $3.00 DAC0808 D/A High-Speed 8 bits — 150ns ±4.5 to ±18 $1.50 DAC0830 D/A Double-Buffered Multiplying 8 bits — 1fJLS + 5 to +15 $5.00 *AII prices listed are approximate. Contact your local distributor for current prices and product specifications. TTLBCD SOURCE + 5V LSB MSB 2V R5 1K — IC1 MC1408 i- *hef R2< IK? TTL BCD SOURCE LSB MSB 15 RS^ - 1K I M 14 16 4, ci ^50pF 13 ■+5V _L C2 ^50pF 16 IC2 MC1408 13 -•--15V R3 1.8K: * + 5V M R f 5K ^> — O V„ R4 200U MSD LSD Voui ov 5 5V 9 9 9.9V FIG. 17— A 2-DIGIT BCD-to-analog converter circuit can be made using an array ol DAC's. changes the circuit's frame of ref- erence so that the amplifiers out- put will swing from - 10 volts to 4- 10 volts. In order to do that, the values of Rl, R2, and R F must be chosen very carefully. When a OOh is sent to the MC 1408, its current output will be mA, but the bias- ing of the op-amp will make the voltage output - 10 volts. As the binary input increments to 7Fh, the analog output will rise to volts. A binary word of FFh will raise the output to + 10 volts. The circuit in Fig. 16 repre- sents a basic D/A sub-circuit. It can be used in just about any sit- uation where 8 bits of resolution and 300 ns of settling time are appropriate, and a bipolar out- put is required. continued on page 76 c 67 HARDWARE HACKER Understanding transforms, video compression secrets, video Crosshatch generator, power electronic resources, and more wavelet breakthroughs. □ON LANCASTER to o I do seem to get several helpline calls each day from those of you who just "can't find" a technical paper at your local library. It's getting so bad that I am thinking of starting up a special "Couldn't find a pig in a dishpan" contest. Pretty near all libraries provide the Interiibrary Loan Sen/ices, through which you can get any copy of any paper from anywhere. All you have to do is ask. There's also the UMi folks that can very quickly ship you a copy of anything from anywhere. Finally, at extra cost, you can instantly get a copy of any paper through the Dialog Information Service that is becoming available at most libraries. More on research topics like these can be found in my Incredible Secret Money Machine and in my Hardware Hacker III reprints. By far the most popular helpline request these days is for... More on wavelets For those of you that came in late, there's a math revolution taking place that we are intently following as an ongoing subject here in Hardware Hacker. This involves wavelet theory, a profound and earth-shattering im- provement on klunky old Fourier transformation which is certain to to- tally change just about any and all advanced electronic topics. There's now a brand new book on wavelets that aims at becoming the "horses mouth" classic. It is known as Wavelets (a catchy title, eh what?), and authored by a long list of name- brand wavelet biggies that start with G. Beylkin. It is published by Jones and Bartlett. No, it is not easy read- ing. Nor is it cheap. Meanwhile, a spunky new outfit by ^ the name of Aware Incorporated is o making a big splash in actual out-the- £ door wavelet products. They have y some wavelet demo and nice simula- g tion software that you can run on a 5 PC, and they seem to be the first 2 ones out the gate with new wavelet transform accelierator chips. Their initial chips are intended for video compression of 512x512 images to either eight- or eleven-bit accuracy. There seems to be several dozen new wavelet papers being released per month now, so it really is a zoo out there. The new wavelet tool is so fun- damental and so important that ev- erybody from the oil exploration geologists to cardiologists appear to be showing intense interest. Most of these wavelet papers are. of course, totally unreadable. But to tune yourself into them, you use the Dialog Information Service at your lo- cal library, and zeroing in on their Inspec, Compendex, or Mathsci data bases. A monthly update of the latest key abstracts should cost you under $20. While you can get the actual papers through Dialog, they are much cheaper through UMI. and cheaper still through those usual Interiibrary Loan snailmail services. Wavelets operate by transforming arrays of numbers into other arrays of numbers. Unlike the classic Fourier transformations, you can simply and quickly zero in on specific portions of a transformation problem, and can do so both locally and globally. You also do not have to worry about any ugly windowing problems. To not get way ahead of ourselves, though, we should first ask how we go about.. Understanding transforms Before we take a new look at video compression, which is one of hottest emerging new wavelet uses, let's ask an even more fundamental question: NEED HELP? Phone or write your Hardware Hacker questions directly to: Don Lancaster Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 Just what is a transform? Why are they so crucially important? And why are certain hardware hacking doors permanently closed to you if you do not learn to use and love transforms? Well, a transform is simply finding a different way of looking at some prob- lem. Done properly, a transform will let something "magic" happen. What kind of magic? That depends. Trans- forms may just change things so they appear differently; may break some- thing down into its fundamental parts; may extract non-obvious stuff in non- obvious ways; could let you separate signals from noise; may let you do more with less; or can perform any of a number of other unique Cand often unexpected) tasks. For instance, you can either listen to music or else transform that music to notes-and-staff notation on a piece of paper. Aside from it being a com- pact way of representing a song, the sheet-music notation lets you know what is going to happen next. It also, for better or worse, standardizes the way the song is supposed to be played. These days, most transforms are done digitally. As Fig. 1 shows us. to do a transform, you take a pile of numbers in a grouping called an array and then apply some rule or set of rules to these numbers. The rules will usually involve adding, shifting, multi- plying, trig functions, and other math stuff. Your result is a second array that holds the "answers" to your transform You might call your first array the real world plane and the second array the transform plane. Think of them as two different worlds. If you can undo what you just attempted with your transform, the transform is said to be lossless, and your reverse process is called an inverse transform. For instance, you might take a pic- ture and transform it. You might then modify the new numbers in the trans- form plane to extract the edge infor- mation, to recognize patterns, count 68 objects, look for differences, or de- blur the image, A final inverse trans- formation could then give you a "new" picture which has changed in some way from the original. One fairly simple yet extremely im- portant transform is known as the linear graphical transform. The linear graphical transform is used to change the sizing, position, rotation, and shape factor of an image or other graphics object. The PostScript computer language is especially adept at making both linear and nonlinear transforms, And, unlike other languages, PostScript automatically does so continuously invisibly, and on the fly, maintaining a separate user space and a machine- dependent device space. Figure 2 shows you a simple linear graphical transform that can convert plain lettering into isometric lettehng. Let's look at some numbers. The lin- ear graphical transform takes any point x.y in your original artwork and converts it into a new point x'.y' by using these formulas: x 1 = Ax + Cy + E y' = Bx + Dy + F \ NEW FROM i DON LANCASTER HARDWARE HACKER STUFF Hardware Hacker Reprints II or III 24,50 Midnight Engineering Reprints 16.50 Incredible Secret Money Machine f2.50 CMOS Cookbook 24.50 TTL Cookbook 19.50 Active Filter Cookbook 19.50 Micro Cookbook vol 1 or II 19.50 Lancaster Classics Library 109.50 Enhancing your Apple I or II 17.50 AppleWriter Cookbook 19.50 Absolute Reset lie & lie 19.50 Enhance 1 or II Companion Disk 19.50 AppleWriter CB or Assy CB Disk 24.50 POSTSCRIPT STUFF Ask The Guru Reprints 1, II or III 24.50 LaserWriter Secrets (HefMac/PC) 29.50 PostScript Show & Tell 39.50 Intro to PostScript VHS Video 39.50 PostScript Beginner Stuff 39.50 PostScript Cookbook (Adobe) 16.50 PostScript Ref. Manual (Adobe) 22.50 PostScript Program Design (Adobe 22.50 Type 1 Font Format (Adobe) 15.50 LaserWriter Reference (Apple) 19.50 Real World Postscript (Roth) 22.50 PostScript Visual Approach (Smith; 22,50 Thinking In PostScript (Reid) 22.50 The Whole Works (all PostScript) 299,50 FREE VOICE HELPLINE VISA/MC SYNERGETICS Box 809-RE Thatcher, AZ 85552 (602) 428-4073 REAL- WORLD SPACE VIRTUAL TRANSFORM SPACE 167 875 956 089 992 145 688 004 371 934 957 846 787 340 675 883 960 536 811 942 290 724 622 030 417 828 332 375 098 022 781 937 830 444 672 TRANSFORM V i) 3SR3VHI MFI013MAHT 312 068 771 514 840 344 141 282 482 587 152 796 157 234 539 584 352 949 583 810 166 739 156 277 410 233 0S9 274 592 512 280 902 666 041 895 FIG. 1— A DIGITAL TRANSFORM takes an array of numbers that usually represents something from the real world. It then applies a math rule or rules to all those numbers to create a new but related array of numbers In an imaginary transform space. Certain "magic" things will happen in the transformation process that can give you elegant new ways of solving advanced electronic problems. Values A through F are plain old constant numbers for any selected transformation. If we think of these as an array of [ A B C D E F ], your A value determines the horizontal scale. The B value decides how much climb you are going to get. And C decides how much lean. The D value sets the vertical scale. The E value provides for a horizontal shift, while the final F value sets the vertical shift. For instance, you might use A and D to separately change the width and height of a font character or mes- sage. A positive C value would make your message oblique or italic, while a negative C would provide a reverse italic effect. Similarly, a positive or negative E gives you a superscript or subscript. And a sneaky trick involving sines and cosines lets you rofafean image, again just by altering A through F in just the right way. Specifically, if is your angle of rotation, just use... A = COSH B = sine C = -sinH D = cose E = F = It may look ugly but works like a champ. The linear graphics transform lets you translate, scale, or rotate any 2-D object any way you like. The point here is that most other transforms work exactly the same way. You start off with some pile of numbers, apply some rules to them, and end up with a second pile of num- bers. And some very good things can happen along the way. The granddaddy transform of them all is called the Fourier transform, while its computer implementation is called a Fast Fourier Transform or one of its improved offspring. Fourier transforms move you from the real world frequency domain on over into the time domain. As an example, if you use Fourier transforms to analyze a square wave, you will break the wave down into a fundamental sine wave and weaker third, fifth, seventh, and other odd higher harmonics. Similarly, you can take a pile of sine waves and add them together by using the inverse Fourier transform in order to get the actual square wave back. Finding the frequencies is called analysis: building the waveform is known as synthesis. Fourier transformation and all its newer offspring get used for nearly all advanced electronic applications. These include detecting earthquakes and heart attacks, robotic vision, side- looking radar, in video compres- sion, picture deblurring. high-defini- x' » i.ooo x + o.ooo y ♦ 0.000 Y" = 0.577 X * 1.000 Y + 0.000 FIG. 2— THE LINEAR GRAPHICS TRANS- FORM is both a simple and very important example of transform use. Here, ordinary graphics and lettering have gotten changed into isometric lettering by using the math shown. 69 POPULARITY black while GRAY VALUES FIG. 3— A HISTOGRAM OF A TYPICAL VIDEO PICTURE shows the "popularity" of each gray level. Since no use gets made of the unt ran stormed edge, pattern, and area info, only a very small amount of useful data compression is possible. POPULARITY negative zero positive WAVELET TRANSFORMED VALUES FiG. 4— WAVELET TRANSFORMED HISTOGRAM of the same pic- ture creates a "sparse" data set having mostly zero or near-zero values by concentrating and redirecting the picture energy. Yet EVERY detail of the original picture is fully and exactly pre- served! Extensive compression can now be done. Q z o a: y- o LU Q < 70 tion television, music synthesizers, sonar, geophysical exploration, holo- grams, spectrum analysis, machinery testing, and scads more. As we've seen, the real excitement behind wavelets is that it does all of the things that Fourier transformation already does. Only wavelets do it far faster, far better, and much cheaper. Wavelet transformations also seem adept at localizing certain features. such as the leading and trailing edges of a square wave. Which is something that gives Fourier fits. Probably the hottest example of wavelet mania to- day involves... Video compression We are smack in the midst of a multimedia revolution that will let you directly manipulate top-quality pic- tures, artwork, and even superb ani- mation on a personal computer. The big problem is to squash the informa- tion content of a high-quality color image down into a manageable space without degrading the picture too much, The HDTV (high definition tele- vision) people are grappling with their version of the same problem — How can you get all of those pixels squas- hed down into an acceptable trans- mission bandwidth? Wavelets promise an exciting new solution to video compression. One that is fast, cheap, easily imple- mented in hardware, massively paral- lel, low on artifacts, and can give you compressions as high as 100:1. And, what is even more exciting, it seems that researchers in human and animal vision are freshly discovering that either the wavelets or something very much akin to them is involved in nature's way of resolving the same types of visual and aural problems. So. something really heavy seems to be coming down here. What makes a picture different from completely random pixels? The usual answers are edges, patterns, and large areas where the colors and shading change little if at all. If a pic- ture is nearly random and if you must have everything in that picture, then there isn't much you can do to squash it down toasmallersize. On the other hand, if there are lots of edges, pat- terns, and large areas, and if some amount of visual degradation is al- lowed, then you can often squash your picture down considerably, pos- sibly as much as 100:1. Figure 3 shows you a histogram of a typical image. In this case, there are 256 gray levels, and each level gets used by the height of its bar as shown. Despite your usual image having lots of edges, patterns, and big areas, the histogram looks more or less like random noise. But, apply a wavelet transform to the same picture, and you get the surprising histogram of Fig. 4. Wave- lets are chosen that zero in on extrac- ting key edge, pattern, and area information. The amazing result is that most of the values in your new histogram are zero and thus can be safely ignored! An array with lots of zeros in it is called a sparse data set. By going to a fancy Huffman or a similar coding scheme, sparse data sets can be stored or transmitted much more compactly than an array in which every value is equally important. There is usually a two-step process involved in video compaction. You first try to concentrate your picture energy in as few array numbers as possible, zeroing out as many of the others as you can. Then you code the final results as densely as you can. As a reminder, a wavelet transform works just like any other transform. You start off with the first pile of num- bers, play several simple math games with them, and end up with the sec- ond pile of new numbers. In the wave- let case, your math games are simple additions, shifts, and rotations. Math that is far less hairy than the fancy trig needed with conventional Fourier or DCT Transforms. There are many popular wavelets, and new ones are being discovered daily. A typical compression wavelet need act only on a very few adjacent values in your original array and can use only simple shifts and adds. The wavelets are usually applied to rows in the array, and then reapplied to the resultant columns. So far, we have thrown nothing whatsoever away. With some sneaky coding, you r exact picture can now be stored in one third or less the space as the original. Or modemed in one third the time or broadcast in one third the bandwidth. And you can re- verse the process at any time to get your exact picture back. But. we can do much better. The eye can resolve some things quite well, and others poorly. You sim- ply do not see some details, and others are too subtle to worry about. By 2eroing out several more of the remaining numbers, and by being crude about how accurately you code the rest, you can trade off picture quality for added compression. And your changes in quality are progressive and subtle. Instead of picking up obvious "jaggies" as you reduce your picture's information content, you simply add broadband noise to it. Which is a much more pleasant and far less noticeable form of image degradation. There are two papers on wavelet video compression that I've found both readable and useful. The first is Application of Compactly Supported Wavelets to Image Compression from William Zettler and the rest of the crew at Aware. Free single copies are available from them on request. Secondly, while nearly anything on wavelets by John Daugman is a good choice, his Entropy Reduction and Decorrelation in Visual Coding by Oriented Neural Receptive Fields, in the IEEE Transactions on Biomedical Engineering, volume 36. number 1, January 1989, is outstanding. Don't let the long title scare you away on this one. It is both a good intra to wavelet video compression and a look about how nature may be already using the wavelets to solve thorny visual problems. Should you want to explore the concept of histograms Further, check out my HSTOGRAM.PS, available on GEnie PSRT as file #146. The compression shootout All of this leads to an interesting dilemma. As we have seen in past issues and in the Hardware Hacker III reprints, the previous all-time cham- pion video squasher is called the Discrete Cosine Transform. A crew known as the Joint Photographic Ex- perts Group is in the final throes of making the DCT a standard. You can get a free single copy of the JPEG Technical Standard, Rev. 8 through Adobe Systems if you want further details. This is a "must have" document if you are at all interested in video compression. NAMES AND NUMBERS Active Electronics 11 Cummings Park Wobum, MA 01801 (617) 932-4616 CIRCLE 301 ON FREE INFORMATION CARD Adobe Systems 1585 Charleston Road Mountain View, CA 94039 (415) 961-4400 CIRCLE 302 ON FREE INFORMATION CARD Aware Inc One Memorial Drive Cambridge, MA 02142 (617) 577-1700 CIRCLE 303 ON FREE INFORMATION CARD Dialog Information Services 3460 Hillview Avenue Palo Alto, CA 94304 (415) 858-2700 CIRCLE 304 ON FREE INFORMATION CARD Digital Digest 4063 N Goldenrod Road, Ste. 3 Winter Park, FL 32792 (407) 671-0185 CIRCLE 305 ON FREE INFORMATION CARD Elector Electronics USA PO Box 876 Peterborough, NH 03458 (603) 924-9464 CIRCLE 306 ON FREE INFORMATION CARD GEnie 401 North Washington Street Rockville, MD 20850 (800) 638-9636 CIRCLE 307 ON FREE INFORMATION CARD Jones & Bartlett 20 Park Plaza Boston. MA 02116 (617) 482-3900 CIRCLE 308 ON FREE INFORMATION CARD Kindt-Collins 12651 Elmwood Avenue Cleveland, OH 44111 (216) 252-4122 CIRCLE 309 ON FREE INFORMATION CARD National Semiconductor 2901 Tasman, Suite 105 Santa Clara, CA 95051 (408) 562-5900 CIRCLE 310 ON FREE INFORMATION CARD At any rate, an awful lot of people have spent an awful lot of time and money to make the DCT a major new video-compression standard. Even PostScript Level II now has built-in DCT filters, and dozens of firms are offering or about to offer DCT com- pression solutions. NEC Electronics PO Box 7241 Mountain View, CA 94039 (800) 632-3531 CIRCLE 311 ON FREE INFORMATION CARD OKI Semiconductor 785 North Mary Avenue Sunnyvale, CA 94086 (408) 720-1900 CIRCLE 312 ON FREE INFORMATION CARD PC Techniques 7721 E Gray Road, Ste. 204 Scottsdale, AZ 85260 (602) 483-0192 CIRCLE 313 ON FREE INFORMATION CARD Plessey Semiconductor PO Box 660017 Scorts Valley, CA 95067 (408) 438-2900 CIRCLE 314 ON FREE INFORMATION CARD RF Prototype Systems 9393 Activity Road, Ste C San Diego, CA 92126 (800) 874-8037 CIRCLE 315 ON FREE INFORMATION CARD RTTY Journal 9085 La Casita Avenue Fountain Valley, CA 92708 (714) 847-5058 CIRCLE 316 ON FREE INFORMATION CARD Shreve Systems 3804 Karen Drive Brassier City, LA 71112 (800) 227-3971 CIRCLE 317 ON FREE INFORMATION CARD Soft Solutions 907 River Road, Ste 98 Eugene, OR 97404 (503) 461-1136 CIRCLE 318 ON FREE INFORMATION CARD Rolf K Taylor RFD#1, Keeler Lane North Salem, NY 10560 (914) 669-5421 CIRCLE 319 ON FREE INFORMATION CARD UMI 300 North Zeeb Road Ann Arbor, Ml 48106 (800) 521-3044 CIRCLE 320 ON FREE INFORMATION CARD The only little problem here is that the wavelet transforms pass the DCT like it was sitting up on blocks. It ap- pears that anything that the DCT can handle, wavelets can do faster. £ cheaper, better, and with far fewer E< objectionable artifacts. ^ In particular, there are background 2 71 POWER ELECTRONICS RESOURCES Asea Brown Bovari 1460 Livingston Avenue North Brunswick. NJ 08902 (201) 932-6000 CIRCLE 321 ON FREE INFORMATION CARD C & H Sales 2176 East Colorado Blvd Pasadena. CA 91107 (213) 681-4925 CIRCLE 322 ON FREE INFORMATION CARD Fair Radio Sales PO Box 1105 Lima, OH 45802 (419) 227-6573 CIRCLE 323 QN FREE INFORMATION CARD Galco 26010 Pinehurst Drive Madison Heights, Ml 48071 (800) 521-1615 CIRCLE 324 ON FREE INFORMATION CARD Herbach & Rademan 401 East Erie Avenue Philadelphia, PA 19134 (215) 426-1700 CIRCLE 325 ON FREE INFORMATION CARD International Rectifier NASA Tech Briefs 41 East 42nd Street, Ste 921 New York, NY 10017 (212) 490-3999 CIRCLE 330 ON FREE INFORMATION CARD PCIM 2472 Eastman Avenue, Ste 33-34 Ventura, CA 93003 (805) 658-0933 CIRCLE 331 ON FREE INFORMATION CARD Powerex Hillis Street Youngwood, PA 15697 (412) 925-7272 CIRCLE 332 ON FREE INFORMATION CARD Power Semiconductor 600 West John Street Hicksville, NY 11802 (516) 933-3000 CIRCLE 333 ON FREE INFORMATION CARD Semikron PO Box 66 Hudson, NH 03051 (603) 883-8102 CIRCLE 334 ON FREE INFORMATION CARD SGS 233 Kansas Street El Segundo, CA 90245 (213) 772-2000 CIRCLE 326 ON FREE INFORMATION CARD 1000 East Bell Road Phoenix, AZ 85022 (602) 867-6259 CIRCLE 335 ONFREEINFORMATIONCARD Motion Box 6430 Orange, CA 92613 (714) 974-0200 CIRCLE 327 ON FREE INFORMATION CARD Siemens 2191 Laurelwood Road Santa Clara, CA 95054 (408) 980-4500 CIRCLE 336 ON FREE INFORMATION CARD Motion Control 800 Roosevelt Road. Ste E-408 Glen Ellyn, IL 60137 (708) 469-3373 CIRCLE 328 ON FREE INFORMATION CARD Surplus Traders Winters Lane, Box 276 Alburg. VT 05440 (514) 739-9328 CIRCLE 337 ONFREEINFORMATIONCARD Motorola 5005 East McDowell Road Phoenix, AZ 85008 (800) 441-2447 CIRCLE 329 ONFREEINFORMATIONCARD "tiling" effects using the DCT, but none using wavelets. Your wavelet transform computations are quite simple, and much easier to realize in standard or near-standard hardware. g Wavelets are also good at building up z the "big lumps" first, followed by finer § detail. That gets important in anima- te tion or a rapidly changing video tj scene. ^ So, I guess we are going to shortly 5 see the answer to the question 2 "What happens when a bunch of Teccor Electronics 1801 Hurd Drive Irving, TX 75038 (214) 580-1515 CIRCLE 338 ONFREEINFORMATIONCARD people spend lots of time and effort creating a new standard that is clearly and ludicrously obsolete before the ink on the final version is dry?" Stay tuned on this one- Power electronics resources Where can you go to pick up a replacement 3000 amp, 2000-volt SCR for your locomotive? The an- swers to questions like that one in- volve power electronics, a somewhat arcane and rather specialized back- water to the ongoing solid-state elec- tronics revolution. As our resource sidebar for this month, I've tried to gather together some sources for all the "Big Mutha" semiconductors and related parts. That's stuff you might be getting into if you are now experimenting with electric vehicles, machine-tool con- trols, AC variable-speed motor driv- es, welders, industrial controls, and similar high-power goodies. An old line distributor by the name of Galco does seem to be the best one-stop source for power semicon- ductors. Their Galco Gazette is free, while their 1500-page main catalog is a refundable $15. A few of the many insider trade journals addressing power elec- tronics include PCIM. Motion, NASA Tech Briefs, and Motion Control. Hacker surplus power electronics seems catch-as-catch-can. But you can try Fair Radio Sales, C&H Sales, Surplus Traders, or else Herbach and Rademan. Several of the more important manufacturers of the higher power semiconductors and support prod- ucts include Asea Brown Bovari, Siemens, Powerex, Power Semicon- ductors, SGS, Plessey, International Rectifier, Motorola, Teccor, and Semikron. Most of them have exten- sive data books and application notes available. Once again, I have a hollow feeling that I missed something obvious or important on this list. For one of our usual contests, just tell me about it. Dot and bar generator Plessey Semiconductors has just revised a bunch of great data books, including their Power Control IC Handbook and their Satellite Cable and TV IC Handbook. That revised gem is chock full of all sorts of good- ies ranging from infrared remote con- trols to teletext, synthesizers, and satellite downlink chips. One of their other chips you may find of interest is their ZNA234E TV pattern generator. The chip gener- ates monochrome video patterns in- cluding dots, vertical lines, horizontal lines, Crosshatch, or gray scale, and runs off a single +5-volt DC supply. Figure 5 shows a typical circuit. A crystal frequency of 2.520 MHz is required for a 525-line NTSC output. An external RF modulator could be added for antenna-driven test needs. 72 o+5V gray adjust gray bars horizontal lines Crosshatch white dots vertical lines 1N4148 -o— — o- pattern select 2.520 Mhz Xtal 330H 1K video 2N3904[ i~ ,,1K output sync video level level FIG. 5— A MONOCHROME TV pattern generator using the Plessey ZNA234E generates sync, blanking, gray bars, lines, dots, and Crosshatch patterns. This appears to be an older bipolar chip, since the supply current is an appallingly high 135 miiliamperes. Yes, full interlace is provided. Let me know what new uses you can come up with for this chip. New tech literature There's a major new data book from NEC Electronics on Infrared Re- mote Control IC's. And another one on Voice Synthesis LSI obtainable from OKI Semiconductor. From National Semiconductor, a new Guide to Video Products. And for general low-cost hacker hardware, a 1991 Active Electronics catalog. One good source of Mac repair parts and service information is Soft Solutions, while Rolf Taylor offers Ap- ple II repairs. Exchange parts for both families are available through Shreve Systems. A new line of ultra-high-quality fully professional RF ground plane bread- boards is available from RF Prototype Systems. For a rather unusual mechanical re- source Kindt-Collins offers all sorts of industrial waxes you can use for machining, CAD/CAM, mold mak- ing, investment casting, protection, and similar needs. Even water-soluble waxes are offered. A pair of wildly different ongoing hacker magazines that are going great guns are Elector USA, chock full of hands-on construction proj- ects, many with a European or conti- nental bent; and Jeff Duntemann's really great PC Techniques, an inten- se software and hardware computing resource. Two newsletters of interest to any of you digital ham radio types include Digital Digest and R7TY Journal. If you are at all interested in the PostScript language, do start out with my LaserWriter Secrets book/ disk combo, Adobe's "blue" PostScript Cookbook, or their "red" PostScript Reference Manual II. All three are available through my Synergetics, or ordered via GEnie PSRT email. We also now have the Hardware Hacker III and Midnight Engineering I reprints available, which have the latest and best of all these columns in them. All edited, revised, corrected, and indexed. Finally, I do have a new and free mailer for you which includes dozens of insider hardware- ha eking secret resources. Write or call for info. Our usual reminder here that most of the items that have been men- tioned in this column appear either in the Names and Numbers or in the Power Electronics sidebars. As always, this is your column and you can get technical help and off- the-wall networking per that Need Help? box. The best calling times are weekdays 8-5, Mountain Standard Time. Let's hear from you. R-E Safety, Security, Convenience, Entertainment and Energy Management Home Automation from Heath, the catalog that has it all... Enter the world of Home Automation. Remote lighting and appliance controls. Security alarms and lighting. Automated thermostats. Video monitoring systems. Whole-house security systems. They're all yours in the Heath Home Automation Catalog, To receive your FREE copy, call today toll-free. 1-80G44-HEATH (1-800444-3284) AUMATIOJ ef. kiHti Heath Company Marketing Dept. 020-070 Benton Harbor, Ml 49022 CL.807R1 I 2 CIRCLE 86 ON FREE INFORMATION CARD 73 WM A Distortion Primer — Part 2 LARRY KLEIN The most well-known of the "non-standard" distortions — transient intermodulation (TIM) — achieved prominence in the early 1970s, mostly through the work of Matti Otala, a Finnish engineering researcher. He rediscovered that un- der certain conditions, amplifiers using high levels of overall output-to- input tor globaD negative feedback would experience input overload even though the applied signal was theoretically too small to cause such a problem. I say rediscovered, be- cause the effect had been docu- mented, discussed, and solutions outlined in the early 1950s. In a nutshell, the TIM story is this: A rapidly changing audio signal — mean- ing one with high-frequency compo- nents — would overdrive a feedback amplifier's input stage, while a signal of the same amplitude, but without high frequencies, would go through without problems. The overload oc- curred because the amp's input stage parameters assumed operation with the gain reduction of negative feed- back, but the feedback signal did not get back to the input fast enough to prevent overload. A basic solution to TIM is to design for sufficient ampli- fier bandwidth — before feedback — to ensure that high-frequency signals can slew (travel fast enough) through the amplifier to avoid problems. To- day, competent engineers can easily achieve adequate slew rate — and thereby forestall TIM — without really straining very much of their design talents. Marketing esoteric distortions If, as I (and others) claim, the distor- g tion problem is essentially trivial in 2 today's amplifiers, why all the tech- § nical papers and amplifier advertise- rs ments touting recently invented/ Jj discovered varieties of distortions and their cures? As far as I can tell, TIM and other similar obscure ampli- fier problems appeal to two groups: o < tr engineering academics seeking scholarly publishing credits and, es- pecially, manufacturers and their ad- vertising agencies. Audio manufacturers, in an annual effort to differentiate their new prod- ucts from those of their competitors, regularly discover — and eliminate — previously unrecognized sources of distortion. That reflects the need to ascribe special audible virtues to products that are really very good but. in truth, are no better than those of their competitors. If sales of a man- ufacturer's latest models can be en- hanced by incorporating a newly developed lateral-feedback circuit to eliminate recently discovered prob- lems of side-slip distortion, why not go for it! In regard to those dedicated lis- teners who continue to hear prob- lems or special desirable qualities in certain amplifiers. I would be willing to bet an extremely expensive set of dia- mond-encrusted tweeter cones that what they are hearing, for better or worse, has far more to do with minor frequency- response deviations than with any kind of old, new, or yet-to-be- discovered amplifier distortion mech- anism. Loudspeaker distortion No one argues that loudspeakers are anywhere as distort ion -free as amplifiers. In essence, a loudspeaker system is required to convert the electrical audio waveform supplied by an amplifier into an analogous three- dimensional acoustic waveform. Considering that loudspeakers do their jobs using an assortment of driv- en diaphragms vibrating in special boxes, the wonder (as someone once said of a chess-playing dog) is not that it does it well, but that it can do it at all! The basic loudspeaker problem is linearity of transduction. That means that the speaker cone (and the voice coil that drives it) must move in exact accord with the audio input signal. Voice-coil motion constrained by its suspension or operating in a magnet- ically nonlinear portion of the voice- coil gap will generate large amounts of second- and third-order harmonic distortion. And any voice-coil move- ment not coupled accurately to the cone, and any cone movement not directly controlled by the voice coil, will distort the sound in some way It's clear from test data and careful listen- ing that in the last 15 to 20 years driver design and performance have improved dramatically. Assessing distortion About 1 5 years ago, I found myself on a business trip in England visiting the Rank HiFi speaker research and manufacturing facility. An unexpected bonus of my visit was a day-long meeting with Dr. Peter Fryer, who was then deep into an investigation of speaker distortion and all its ramifica- tions. One of his primary objectives was to assess the audibility of the types and levels of distortion com- monly produced by loudspeakers. Since IM distortion, as mentioned last month, is generally thought of as one of the worst culprits in making things sound bad. Fryer tackled it first. A distortion generator was built that could be set to inject a calibrated amount of IM ranging from 0.1% to 10%. A virtually distortionless ampli- fier and speaker system were de- signed and built and served as the "test bed" for all of the subsequent experiments. Much to everyone's surprise, it was necessary to crank up the IM level to 5% or 6% before it became audible on typical complex musical material, rock or classical. With sim- pler music, such as a solo piano, 2% IM was clearly audible. And. when sine waves were used as the test signals, IM levels of 0.1 percent could be detected under carefully con- trolled conditions. None of that sur- prised me, since the findings neatly replicated the results of some ampli- 74 fier IM tests that I had been involved in four years earlier. Fryer's next series of tests involved kinds of distortion not found in ampli- fiers. Delayed resonance was some- thing that had concerned the British for years, but to my knowledge was never an issue among U.S. speaker designers. Simply described, it is the tendency of parts of a driver's cone assembly to store energy and con- tinue to release it for some millise- conds after the original signal has ceased . It was described to me (you ' II have to imagine the British accent) as "the speaker carrying on broadcast- ing long after the program has finished." Unlike IM tests, the delayed-reso- nance research results were not easi- ly summarized in numerical form, A basic finding was that broad low Q resonances were far more audible than sharper peaks covering nar- rower bands, probably because the low-Q resonances were activated for a greater proportion of the signal. When the peak is very broad and low Ca of less than 1 ), the audible effect is simply an increase in level over the affected portion of the frequency band. The primary finding of the research was that it behooves the speaker- driver (and speaker- system) designer to eliminate resonances whenever possible, a task that has been signifi- cantly facilitated in the past decade by laser analysis of cone movement and modal vibration analysis of speaker-cabinet walls. Doppler distortion A distortion that excites partisan bickering among speaker-system de- signers. Doppler distortion occurs when a cone is undergoing large low- frequency excursions while simulta- neously reproducing high frequen- cies. The theory is that the high frequencies reaching the listener's ears will be alternately compressed and stretched by the low-frequency movements of the cone. There is no question that speakers do produce Doppler distortion. The real question is: How audible is it under normal playing conditions? A Doppler distortion generator was developed using a delay line that could be varied at a rate determined by a low-frequency signal. A total voice-coil movement of more than two inches could be simulated, cer- tainly more than enough to simulate any real-worid condition. Fryer sum- marized the results of days of experi- ments by saying that, with the possible exception of small full-range speakers (such as are found in porta- ble radios), normal loudspeaker sys- tems used in the home will never produce enough Doppler distortion for it to be audible. The bottom line As with amplifiers, most of what we hear going wrong in hi-fi speakers is in the frequency domain. However, straightening out an amplifier's fre- quency response is duck soup com- pared to the task facing a speaker designer. If an amplifier's response has a bump or a dip, a few resistors and capacitors will usually flatten it nicely. Speaker frequency response, on the other hand, involves manip- ulating magnetic, mechanical, and acoustic variables, in addition to the electronics of the crossover network. But improved materials and know- how continue to make the task im- measurably easier. And anyone who has done any comparison listening in the past dozen years knows that speakers continue to improve. R-E »Save on cable rental fees !» CABLE TV DESCRAMBLERS WE'LL BEAT ANY PRICE ! CALL TOLL- FREE 1-800 284-8432 JERROLD-TOCOM-ZENITH HAM LIN-OAK-PIONEER SCIENTIFIC ATLANTIC •24 HOUR SHIPMENTS I ■MONEY BACK GUARANTEE I •FREE CATALOG & INFO I • QUANTITY DISCOUNTS ! MASTER CARD / AM EX / VISA / C.O.D. SHI ^^^h IMattarCaid. JtBtJB VISA Have make and model number of equipment used in your area ready 1-800-284-8432 CABLE WAREHOUSE 4700 H. HIATUS R0AD,SUNRISE,FLA.33351 V WO FLORIDA SALES J CIRCLE 189 ON FREE INFORMATION CARD Earn Your B.S. Degree in ELECTRONICS or COMPUTERS By Studying at Home Grantham College of Engineering, now in our 4 1st year, is highly ex- perienced in "distance education" — teaching by correspondence — through printed materials, computer materials, fax, and phone. No commuting to class. Study at your own pace, while continuing on your present job. 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Six insertions $950 each. Twelve insertions $925 each. Closing date same as regular rate card. Send order with remittance to Engineering Admart, Radio-Electronics Magazine, 500-B Bi-County Blvd.. Farmingdale. NY 11735. Direct telephone inquiries to Arline Fishman. area code-1-516- 293-3000. FAX 1-516-293-3115. Only WO% Engineering ads are accepted for 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 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. Sox 240, Massapequa Park, NY 11762-0240. LINEAR IC EQUIVALENTS & PIN CONNECTIONS Linear IC Equivalent* and Pin Connections BP141 — Shows equivalents & pin con- nections of a popular user-oriented selection of European, American and Japanese liner IC.'s 320 pages, 8 x 10 inches. $12.50 Plus $2.75 shipping. ELECTRONIC TECHNOLOGY TODAY INC., PO Box 240, Massapequa Park, New York 11762-0240. CIRCLE 179 ON FREE INFORMATION CARD CO O Z O □c F o LU _J LU I o Q < CC AC TO DC CONVERTERS continued from page 67 BCD-to-analog converter The input signal to the MCI 408 does not have to be pure binary. An array of DAC's can be configured to convert a 2-digit BCD input into a corresponding analog output voltage. Figure 17 shows a circuit that can be used as a BCD-to-analog converter. Notice that only the lower four bits of each DAC are used to ac- cept the BCD signal. The four most significant bits are grounded. The TTL signal can be provided through discrete sources {such as thumbwheel switches) as well as BCD coun- ters or other binary circuits. The most significant digit DAC drives the op-amp directly. The output from the least significant digit DAC is divided by 10 through a resistor network and added to the signal from the most signifi- cant digit to produce the 0- to 10- volt output. The value of the feed- back resistor R F can be adjusted to vary the output range from up to 10 volts. A BCD input of 00 will yield O volts out. As the BCD input in- creases to 50, the output voltage will climb to 5 volts. An input of 99 will give an output oflO volts. Since the input range is now only 100 steps (OO to 99), the analog output will travel from O to 10 volts over 100 steps instead of the 256 steps that all 8 bits would normally offer. Although a BCD to analog convertor sacrifices +5V i CHANNEL 27 (\J 28 16 23 12 11 OE V, CHO cm CH2 ADCOOIIH CH3 CHAfJNI CH4 ADC CHS CH6 CH7 -v REF A B C START ALC 6 + 5V- CLOCK INPUT 500kH<: END rtF raiNvrnsmrj o (EfXl TRI-STATI } DIGITAL output: S1 START 4.7K PULLDOWN * RESISTOR v IN MSB TTL OUTPUT LSB ov 2.5V 1 1111 1 1 5V * 1 1111 1 1 FIG. 18 — AN A/D converter circuit using the successive approximation technique. some resolution, it can provide interesting advantages where special inputs are required. Basic A/D application A basic A/D converter can be built using a Texas Instruments ADCO808 as shown in Fig. 18. That is also a generic circuit which can be used to interface an analog voltage to a computer port or other digital circuit. The ADC0808 uses the suc- cessive approximation method of A/D conversion. In normal opera- tion, an analog voltage (from O to + 5 volts) is applied to the IC at V [N . When a conversion is re- quired, a TTL-level start con- version signal is applied to the converter. In that case, a momen- tary pushbutton is used to pro- vide the pulse. Any other TTL logic pulse may be used to start the conversion as well. A fast square-wave clock source (of about 500 kHz) steps the ADC quickly through its conversion process. When the conversion is complete, the IC will latch the digital result onto the output pins and generate an end of con- version signal. Since that is a to +5-voIt ADC, a 0-volt input will generate a binary OOh at the output. An input of 2.5 volts output 7Fh. and a full 5-volt input output FFh, R-E 76 JILJ^.HIM^Iire A new beginning for this column. JEFF HDLTZMAN Amiga owners are a small but extremely vocal minority. As expected, my remarks in the April issue generated a fair amount of controversy. In fact, letters continue to arrive. Originally I planned a re- sponse for this month but. due to high reader interest, I will wait another month. New directions This month is special in otherways, however. It marks a new beginning for this column. For the past four or five years I have focused mostly under the hood, talking about products and technologies in some detail. If you follow the column, you've probably noticed a shift in the past few months to higher-level issues. Beginning this month, I will begin the process of for- malizing the shift. From now on, the column will con- sist of three major sections: reader interaction, products and tech- nologies, and industry focus. The lat- ter represents the biggest change in format. Each month I will examine what's happening in industry in two broad areas: important new innova- tions and the movements toward standards and open systems. I will summarize what has happened, based on both published and un- published reports, and then specu- late on what It means. In addition, because at heart I'm really a hands- on kind of person, I'll provide regular product cameos and occasional in- depth reviews. I hope you enjoy the new format: either way, your opinion is welcome. Standards and integration It's a commonplace that the U.S. is slipping in several industries: com- puter systems (both large and small) and semiconductors, to mention a couple. What are the computer and chip companies doing about it, if any- thing? Large companies are slimming down by eliminating lots of jobs. IBM, for example, recently cut its ranks by 10,000; last year, DEC "downsized" by about 4000. Cutting the fat helps reduce overhead, but doesn't help solve underlying problems, the single largest one of which is lack of respon- siveness to real customer needs. Detroit didn't pay attention when the customer said I want small, effi- cient, quality-built cars, So Japan stepped in. Nobody in this country listened when the customer said I want small, sexy electronic devices. So Japan stepped in. And Korea. Ad nauseam. So far the computer industry has been relatively immune to foreign in- vasion. Nonetheless, customers aren't happy. One of the biggest bones of contention is proprietary standards: incompatible user-inter- face conventions, networks that won't talk to each other, incompatible data formats among application pro- grams that for all intents and pur- poses are functionally identical,... ad nauseam. In some of those areas, the indus- try has made significant progress. For example. IBM's System Application Architecture (SAA) includes a user- interface component. Common User Access (CUA) that is rapidly becom- ing the de-facto standard, with sup- port by Windows, OS/2 PM. and OSF/Motif. In the world of network standards, support for the seven-layer OSI refer- ence model has been increasing steadily. Effective August 1990, the U.S. Government mandated that all future purchases must be compliant with GOSIP, the Government OSI Profile. Because the feds are among the largest market for data-process- ing equipment, that mandate has al- ready had a calming effect on the industry. As for cross-platform data incom- patibility, that's a problem that is only now beginning to be addressed. Sure, there are translator programs that convert among various database, graphics, and word-pro- cessor formats But those are inel- egant solutions, akin to asking a diner to prepare his own food. Customers want more. We've seen limited, platform-spe- cific solutions to this problem before. For example, integrated software (e.g.. the Smart series, Microsoft Works), followed by data-exchange format standards (e.g., DDE under Windows and OS/2). Probably the most comprehensive approach to date is being developed by the Object Management Group, a consortium of major computer vendors. Microsoft recently joined the OMG. leaving IBM the only major holdout. OMG is defining a set of application program interfaces (API's) for managing ob- jects in a networked computer en- vironment. If you know anything at all about the term, you know that an object consists of both data and code that acts on that data: the latter are called methods. Under the OMG's scheme, ap- plication programs will become dumber, because objects will be- come smarter. Applications will be dumber because they won't have to try to interpret every type of data un- der the sun. Therefore, they will be more efficient, easier to develop, and more reliable. Data objects will be smarter, hence more useful, because they will know how to do things like print and display themselves. Watch for this type of technology to rapidly change the way we think about "data" and "programs." A related but perhaps even more ambitious effort is a group called Pa- triot Partners, composed of 75 as- signees from IBM and Metaphor. Patriot Partners is attempting to de- fine and build an object-oriented op- erating environment that will run on multiple operating systems (Win- dows, OS/2, OSF/Motif) and will provide a common interface to each. ^ An application built for this environ- r^ ment will run on any underlying OS. ^ Borland has announced support for S 77 o O or o Q < tc I'm not much of an artist, but I love PC-based drawing tools so much that I can't resist getting my hands dirty from time to time, tn the PC world, the two premier general-purpose draw- ing packages are Corel Draw and Mi- crografx Designer, Designer came out first, and I fell in love with it. Then Corel Systems introduced its prod- uct, which is a model of user-interface design. Subsequently, the two pro- grams continually leapfrog each other by increasing features and usability Version 3.0 of Designer is Mierografxs latest entry; the package has improved tremendously since version 2.0. New features include Bezier curves, much improved text handling, much improved support for symbols {an area in which Corel is stitl struggling), tracing of bitmap files (PCX, TIFF, etc), and much im- proved on-line help and printed docu- mentation. Designer's support for layers and grids is like many CAD programs; Corel also lacks in that area. (Corel leads in 3-D effects, however.) Designer comes with thou- sands of pieces of clip-art, including many electronics symbols: op-amps, digital logic symbols, diodes, coils, resistors, capacitors, plugs, jacks, speakers, switches, transistors — most of what you need, and of course you can create your own. The pro- gram lists for $695. Micrografx, 1303 Arapaho, Richardson, TX 75081. (800) 733-3729. (214) 234-1769. CIRCLE 4T ON FREE INFORMATION CARD The notion of a "dictionary" on a PC used to be ludicrous. Now that virtually all PC's contain hard disks, the idea is much more appealing. Several companies have released PC-based dictionaries; the best is the American Heritage Electronic Dic- tionary. It runs as a RAM-resident program that you can pop up within your word processor (see Fig. 1). It contains the most complete defini- tions of any electronic PC-based dic- tionary I've seen, and includes etymologies (word histories). It also contains functions for searching with wildcards, for anagrams, boolean searches, and a thesaurus. For ex- ample, can you name any English word that contains all the vowels in order? Think before you read the an- swer below. The AHED runs fine under Win- dows; in 386 Enhanced mode, you can pop the program up in a simu- lated text-mode screen. The program also comes with a basic word pro- cessor called Writer. Without Writer, (ftrrouKcys) Fi-Lookitp F2- Thesaurus FID-Exit -h"enu e«Iec*tron»fcs (i-lek~trahn«iks, EE«lek-) noun: (used tilth a singular werb), 1. The science and technology of electronic devices and systerts. Z. The connercial industry of electronic devices and systens. DAHZQ £1111935120 HED ERB 48 0S-06-9B 12:43 EDftttZG IBL 42??& 03-67-91 14:16 05-06-90 12:42 Zl files totaling 3126051 bytes cnnsuMng 3143600 bytes of disk space. 9336832 bytes available on Briue D: Uolune label: MIA :\ftH£D> FIG. 1— THE AMERICAN HERITAGE ELECTRONIC DICTIONARY shows pronunciation and word origin, and provides a thesaurus and extensive search capabilities. the AHED occupies about 3.7 mega- bytes of disk space. The AHED lists for $89,95 comes in versions for both PC and Mac, and is available from Houghton Mifflin, One Memorial Drive, Cambridge, MA 02142. (800) 633-4514. (617) 252-3000. Answers; abstemious, ab- stemiousness, abstemiously, adven- titious, adventitiousness, adven- titiously, arsenious, bac- teriophagous, facetious, face- tiousness, facetiously, have it out, sacrilegious, sacrilegiously, sacri- iegiousness, sympathetic nervous system, take into account, take it out on. CIRCLE 42 ON FREE INFORMATION CARD There are lots of menu programs for Windows 3.0 that provide a conve- nient way to organize and launch your applications. The simplest and most elegant I've seen is a little shareware program called Launch. With Launch installed, you click on the desktop background, and hold the left button down. A menu pops up that lists your favorite applications. Highlight your choice, release the mouse button, and you're off. The program includes several con- venience items that you can add to the menu as well, including functions to arrange icons on the desktop and to exit Windows. The program reads the menu from an ASCII text file, so it's easy to create and update. As I write, the program is in version 1.5; 2.0 is due by the time you read this. If you feel overburdened by the fancy menu programs, you'll love Launch, I'll post a copy on the RE-BBS (516-293-2283, 1200/2400, 8N1). I'll also post a copy of ASQ, a pro- gram for analyzing PC memory and hardware configuration. Qualitas (the 386Max people) wrote ASQ and are distributing it at no cost. It's got some advertising hype, but includes a fair amount of system and tutorial infor- mation. Other companies charge $30 to $100 for this type of program. At a recent trade show, I acciden- tally ran into a representative of the Canadian company that wrote and distributes the Electronics Work- bench, a CAD-like program that al- lows you to simulate analog and digital circuits on a PC compatible. As reported here in the December 1990 column, the program is great for beginning and intermediate stu- dents, but at $650, much too expen- sive for individual purchase. My writeup generated a lot of reader in- terest; consequently, the company got together with a large U.S. pub- lishing firm, and expects to release a "personal" version by next fall. Cost should be about $30, and will include some sort of workbook and a func- tional program. Stay tuned for details, or contact the company directly (and tell 'em we sent you). Interactive Im- age Technologies, 49 Bathurst St., Suite 401, Toronto, Ontario, Canada, M5V 2P2. (416) 361-0333. R-E 78 H R-E Computer Admart Rates: Ads are 2V*"x2W. One insertion $995 each. Six insertions $950 each. Twelve insertions S325 each. Closing date same as regular rate card. Send order with remittance to Computer Admart, Radio-Electronics Magazine, 500-B Si-County Blvd., Farmingdaie, NY 11735. Direct telephone inquiries to Arfine Fishman, area code-1-516-293-3000. FAX 1-516-293-3115. Only 100% Computer ads are accepted for this Admart. HOW TO EXPAND, MODERNIZE AND REPAIR PCs AND COMPATIBLES BP271— Includes PC overview, memory upgrades, adding a hard disc, adding floppy drives, display adapters and monitors, installing a co-processor, preventive maintenance, repairs, do it yourself PCs and more. To order your copy send $7.75 plus $2,00 for shipping in the U.S. to Electronic Technology Today Inc., P.O. Box 240, Massapequa Park, NY 11762-0240. SECRETS OF THE COMMODORE 64 Secret* el the GOMKOttOnE BP135 — A beginners guide to the Commodore 64 pre- sents masses of useful data and programming tips, as well as describing how to get the best from the powerful sound and graph- ics facilities. We look at how the memory is organized, random numbers and ways of generating them, graphics-color-and sim- ple animation, and even a chapter on ma- chine code. Get your copy today. Send S5. 00 plus $1.25 for shipping in the U.S. to Electronic Techology Today Inc., P.O. Box 240, Massapequa Park, NY 11762-0240. PROMPT DELIVERY SAME DAY SHIPPING (USUALLY) QUANTITY QUE PRrCE5 5HQWN lor APRIL ». ■.l.UJ.IllD.UiJ.UI.IIU.IJMHi DYNAMIC RAM I4M Board I SIMM I SIMM I SIMM 1 4 Mbit 1 4 Mbit 1 Mbit 1 41 256 1 41 256 1 44256 14464 27C4001 D28F010 27C1000 27C512 27128 I I Mbit 162256LP lor hp U's w 2MB -»Mx9 80 ns 1Mi9 1Mx9 4Mx1 1MX4 1M*1 S56Kx1 256K*1 255Kx4 64Kx4 60 ns 80 ns 80 ns 80 ns 80 ns 100 ns 120 ns 100 ns 1 00 ns EPROM 512KX8 1 50 ns 12BKX8 128KX8 64KK8 16KkB 150 ns 150 ns 120 ns 250 ns STATIC RAM 12BKX8 100 ns 32KxB 100 ns $148.00 ! 1 30.00 ' S S3.00 S s 51.00 || 28.00 j jj 34.00 5 S 5.50 : ? 1, 95 II ! .75 S i 5.75 ■; ; 1.95 || S55.00B; 24.00 wB 16.50 ■ 7.50 ■ 3,40 ■ S15.0ol 6.50fl I OPEN 5' . DAYS. 7.»«uH)-u SHiPVIfl FED-EX ON SA1 SAT DEL OH r ■;■<■.• : «'■>■. i.m ■;■ DECEIVED at- MM HTJ41* COO AVJJLABtE MMtf&H] VISA or UPS CASH COD MICROPROCESSORS UNLIMITED. INC. 74 00:1 r i PtQt'H Ave ' ■ BEGG5 OK 74421 Hit rriinimui-i order (918)267-4961 CIRCLE 61 ON FREE INFORMATION CARD this environment: as the premier sup- plier of object-oriented programming tools, this is exciting news. A related development is Unicode, a consortium of leading computer vendors (IBM, Apple, Microsoft, Sun, Next, Novell, and others) that has begun the process of defining the successor to the ASCII character set. ASCII is a seven-bit code, limited to 128 characters. By contrast, Uni- code is a 16-bit code, allowing 64K characters, enough to represent all western languages unambiguously, and a good start on eastern lan- guages as well. News bits Recession? What reces- sion? After hitting an all-time low in November of 1990. semiconductor sales are on the rise again. The first two months of 1991 set an all-time record, and the Semiconductor In- dustry Association is optimistic that the industry could grow by about 10% this year. MacClones? Apple's continually shrinking market share has finally forced Sculley and crew to understand that they're in business to sell computers, not religion. The company recently acknowledged in- terest in licensing the Mac operating system to vendors of other hardware platforms, most likely including some flavor of Intel chips. With the rapidly increasing popularity of the 386/486, technical problems should be few, as the advanced Intel processors over- come the limitations of earlier pro- cessors that used to make the Motorola family attractive. PolyGlot PostScript. Adobe Systems is ex- pected to announce a PostScript- based utility that allows transparent data sharing across multiple plat- forms, OS Soup. IBM will try to ease skepticism about OS/2 with a marketing blitz designed to promote understanding of the operating sys- tem, applications for it, DOS and Windows compatibility, and futures. Watch for OS/2 2,0 to sweep the industry just like Windows 3.0 has. 486 blues Just when 386-based systems start to become affordable, the 486 moves in as the new high-end option. However, the 486 may penetrate the market much quicker than did the 386. Intel is poised to release several updated 486's, a 50-MHz unit, and a "crippled" or de-featured unit (vari- ously called the P23 and the 486SX) that comes without the math coprocessor, and that runs slower (20 MHz) than a full 486. Remember that even running at the same clock speed, a 486 is about twice as fast as a 386. Several vendors have already announced P23 systems priced un- der $3000. The P23 isn't stopping American Micro Devices, which is shipping 40- MHz versions of its 386 clone. Also, Chips & Technologies and Cyrix have introduced system logic and math coprocessors, respectively, that sup- port the new device. Intel's not scared, however; the company has shown a 486 running at 100 MHz. R-E COLOR BAR GENERATOR continued from page 45 chroma on the whi te bar ( the first bar after horizontal sync) with RIO and R9. Adjustment with Monitor If you have a monitor, hook up the video output of the video gen- erator to the monitor's video in- put and do all the adjustments looking at the white color bar on the left side of the screen. If the red, green, and blue video levels are set up properly the white bar should be full brightness and white. If it is not, adjust R8 for the overall brightness and then adjust RIO and R9 for a pure white bar. We hope you've learned some- thing about color video from this project. Everything is neatly broken into fairly simple blocks so you can be assured of success. If you have an IBM Clone comput- er with a CGA board (or other vid- eo card with NTSC-compatible sync) you can use just the en- c coder section to generate NTSC- % compatible sync and RGB video £ outputs. R-E 2 79 The two most comprehensive electronics Take any 3 books for only $ 9~ as your introduction to the new ELECTRONICS ENGINEERS' BOOK CLUB ELECTRONIC | icciRCurrs WITH I PRACTICAL I APPLICATIONS 2920 $29.95 A wealth of electronic circuits and information on building working devices. 336 pp. . ■ THE Baidittjp Electronics Reference .'"' 3100 $75.00 This quick-reference provides pin -out diagrams, internal block diagrams and schematics, characteristic curves, descrip- tions and applications — for foreign and domestic JCs! 1088 pp. Counts ax 3 msnoom m eletem: 1 £0ItPMENT_ WlTHQlTSERVia 92SS S89.50 "Outstanding, extensive refer- ence to current technology of electronics. Covers everything from principles to applications," —Computer Book Review 2528 pp.. ISOOillus. Counts as 3 ELECTRONIC CIRCUITS VOLUME TWO MM*E .lours: (Pacilic Tirnei yof Y#ijrTiBdi3Utt;.iTR,iN3^we^ Mpn thru Fri. 9:30 am to 5 00 pm w« ant ftot nooonbittc lor ttoo^riirMCAi; m&i Sal. 10.00 am la 500 pm MARK V ELECTRONICS, INC. - 8019 E. Slauson Ave, Montebello, CA 90640 r^-j Q jffl CIRCLE 93 ON FREE INFORMATION CARD ANNOUNCING: AN END TO HIGH MONTHLY CABLE FEES! All Jerrold, Oak, Hamlin, Zenilh. Scientific At- lanta, Magnavox and all specialized cable equip- ment available for shipment within 24 hours. For fast service MC/VISA or C.O.D. telephone or- ders accepted. 60 Day Guarantee [Quantity Dis- counts). Send self-addressed Stamped enve- lope. C.O.D. ORDERS ACCEPTED ^■n, I CABLE-TRON1CS, INC. 1304 E. Algonquin Road Suite SOI Algonquin, Illinois 601 02 CABLE equipment top quality, best prices, warran- ty, satisfaction guaranteed. Scientific AtlantaAJer- rold. Deluxe combo $1 89.00. Standard combo $169.00, Check/money Order.'COD. (301) 829-1521. CABLEPHO, 14703-E Baltimore Ave., Suite 256, Laurel, MO 20707. No Maryland sales! SUPER low prices on computers, motherboards, hard and floppy drives, add-on cards. We have ev- erything. Full line of test equipment at unbeatable prices. Call for free catalog. APPLIED ELEC- TRONIC RESEARCH, INC., Hollywood, FL (305) 987-9785. DESCRAMBLERS, cable TV converters, lowest prices, guaranteed, best quality, special Sacramen- to units. CNC CONCEPTS, INC., Box 34503, Min- neapolis, MN 55434. 1 (800) 535-1843. MICROWAVE antenna — tunable 1.9 — 2.7GH2 TV dish systems under $80.00. SASE, SUNEXX. PO Box 266. Anguilla, MS 38721. FREE catalog. Interfaces for IBM compatibles Dig- ital I/O 43 TTL lines (2ea. 8255s) $69.95, 16 ch. analog input to 5v 8 bit. $89.95. JOHN BELL, 1381 Saratoga St., Minden, NV 39423. (702) 267-2704. WHY retire to FLA? Over half of North Carolina retirees came from Florida — learn why! North Car- olina golf & lake homesites from only $10,900. Free literature 1 (800) 768-7358. 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BOX 802-L9, Carlisle, MA 01741 SURVEILLANCE — Audio/video'infra-red'laser equipment. Industrial or private. 500 item catalog $7.00. SECURITY SYSTEMS, 3017G Hudson PI., New Orleans, U\ 70131. DESCH AMBLING, new secret manual. Build your own descramblers for cable and subscription TV, Instructions, schematics tor SSAVI, gated sync, sinewave, (HBO, Cinemax, Showtime, UHF, adult) $12.95, $2.00 pOSlage CABLETRONICS, Box 3O502R. Bethesda. MD 20824. ROBOTICS! Engines! Inventions! Muscle wires contract with surprising strength when powered. Send business SASE for latest flyer. MONDO-TRO- NICS c/o RE, 2476 Verna Ct., San Leandro, CA 94577 FREE cable and satellite descrambler plans. Send self addressed stamped envelope. MJM INDUS- TRY, Box 531 , Bronx, NY 10461-0208. CATALOG: hobby/broadcasting/HAM/CB; Cable TV, transmitters, amplifiers, surveillance devices, computers, more! PAN AXIS, Box 130-F7, Para- dise, CA 95967 VIDEOCIPHER ll/scanner/cable.'satellite modifica- tions books. Catalog — $3.00. telecOde, PO Box 6426-RE, Yuma, AZ 85366-6426. PEN transmitter: Sensitive micro FM transmitter housed inside standard size pen. Latest surface mount technology. Complete kit and instructions $44.95. MICRONIC-INT., Box 5726, Sherman Oaks, CA 91413. o z O rr H O UJ 6 o PERFECT CABLE CONNECTION !! Perfect Cable Connection is totally committed lo customer satisfaction. Our primary concern •s to provjde you with Ihe highest quaJity conveners and descramblers at Ibe lowest cosl, We empioy Cull lime technicians to insure hassle Free- service and Iroubleshool any silualion. 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ZTACS ■1 ■r H S CALL .fl CALL IB S9 20 79 to tyj ™ CALL All mod ts Cm lot prpcfl? in '* CAll 50 CALL 100 CALL U*l CAU Ffl 3 BA-3B FTH.3 DftX 310S Wfl 1 rv 1 75 J-xl DRj 1 V, n 1 oa to 4ht ID *S 1 1* 10 70 ."0 -LI 20 43 UJ lb 20 65 10 *5 'U 14 50 39 .hi v. 50 CALL 50 40 IUCI 3b 100 3S * too CALL WE WILL MEET OR BEAT ANY ADVERTISED PRICE IN THIS MAGAZINE. PERFECT CABLE CONNECTION 702-358-2763 2209 Oddie Blvd., Suite 321 Spark, NV 89431 WARNING! CABLE BOX DEALERS Consider the facts before you buy after-market cable equipment An industry standard defines 25% of all after-market cable boxes do not work when first tested... All wholesalers advertise low prices. ..but low prices are not enough. Any price is too high if you're without technical support or quality control. Now consider that your success as a dealer depends on the satisfaction of your customers. Wholesale Cable Supply offers services that are near a defined science. And we guarantee 100% satisfaction. Monthly Special • Guaranteed Low Prices State-of-the-Art technical support Top Quality Tested Products Dealer Market Support WHOLESALE CABLE SUPPLY Low Price is only the beginning 1-800-926-6836 723 CAMINO PLAZA, STE. 108, SAN BRUNO, CA 94066 TB-3 or SA-3B 10 lot 48 20 lot - 43 50 lot - 39 100 lot - 39 Z-TAC 10 lot - 149 86 HYPNOTIZE or Relax electronically! Alpha/medita- tion goggles. Complete kit $53,00. Free information. MARK WORLEV; Box 261113, San Diego, CA 92196. SURVEILLANCE transmitter kits! Four models of each; telephone, room, combination telephone/ room transmitters tune from 65 to 305 MHz. Catalog with Popular Communications and Popular Electronics book reviews of "Electronic Eaves- dropping Equipment Design," S2.0C. SHEFFIELD ELECTRONICS, 7223 Stony Island Ave., Chicago, IL 60649-2806. DISTINCTIVE RING SWITCH Add additional phone numbers to a single line with the now Distinctive Hinging service from tha phone company. 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C ENTER VILLE, DH 4S459-4072 A PREMIER Company For more information or a FREE subscription to our catalog call TOLL FREE 1-800-543-4330 Source No. RE-71 c 5 87 CIRCLE 87 ON FREE INFORMATION CARD CABLE TV EQUIPMENT Conveners, Remote Controls, De scramblers, CD Players. JERROLD-OAK-SCIENTTFIC ATLANTA- HAM LIN ZENITH MANY MORE CALL TODAYS V Only quality products sold V Easy to use ^ Satis faction guaranteed V Knowledgeable sales staff V Most orders shipped within 24 hours CALL FOR YOUR FREE CATALOG 1-800-228-7404 MAKE THE CONNECTION NU-TEK ELECTRONICS | 51 14 Balcones Wood Dr.#307 Dept.298 ^^^^Austin i TX^875^^^^^ CABLE TV Secrets — the outlaw publication the cable companies tried to ban. HBO, Movie Channel, Showtime, descramblers, converters, etc. Sup- pliers list included. $9.95. CABLE FACTS, Box 711- R, Pataskala, OH 43062. DO it yourself, systems, upgrades, major brands discounted, save 30% — 60%. Lowest prices anywhere. L.J.H. tNC, call Larry at (609) 596-0656. THIS IS A REGULAR CLASSIFIED AD WITH A TINT BACKGROUND. To have your ad appear like this one, the cost is $3.90 per word. IMPOSSIBLE CABLE SYSTEMS! Zenith PZ ♦ New honest ♦ Starcem 687 ♦ Standard Units ♦ New Generation of TRIM00ES & SB'S. ♦ Quantity prices start at $25 63 Ch Dealers only Call 1-800-933-2242 digital Engineering company oWmerica EDUCATION & INSTRUCTION F.C.C. Commercial General Radiotelephone li- cense. Electronics home study. Fast, inexpensive! "Free" details. COMMAND, D-176, Box 2824, San Francisco, CA 94126. LEARN IBM PC assembly language. 80 pro- grams. Disk $5.00. Book $13.00. ZIPFAST, Box T2238, Lexington, KY 40581-2238. COMPLETE course in electronic engineering. Eight volumes. Includes all necessary math and physics. Free brochure. BANNER TECHNICAL BOOKS, 1203 Grant Avenue, Rockford, IL 61103. CABLE DESCRAMBLERS OAK M3SB COMBO $39.95 Jerrolrj. Zenith, Hamlin, Sci, Atlanta, Pioneer & MORE! OUR PRICES ARE BELOW WHOLESALE! CABLE+PLUB 14417 Chase St. #4ai-A Panorama City, CA 91402 1-800-822-9955 • Other Info. 1-818-785-4500 NO CALIF. SALES - DEALERS WANTED INVENTORS INVENTORS! Can you patent and profit from your idea? Call AMERICAN INVENTORS CORPORA- TION for free information. Over a decade of service 1 (800) 338-5656. In Canada call (413) 568-3753. ECC continued from page 46 go to both D/A converters, IC21 and IC22. To write the informa- tion to IC21 without disturbing the contents of the other D/A con- verter, the CPU must output a 252 to I/O port 54 to lower Ql and Q2 of IC16, followed by a 255 to I/O port 54 to return the control signals to their inactive state. The function of the D/A con- verters in the circuit are to pro- vide a DC offset to the analog input circuitry to compensate for the DC offset produced by each ECG electrode on the patient's skin. Since the offset, in general, is different for each input lead each time the system is con- nected to a patient, a means to measure the offset must be pro- vided. That is accomplished by performing a series of calibration measurements just prior to mak- ing the ECG measurements. Next time we will continue with the construction and operation of the ECG device. R-E #■ % to o I O LU O Q < tr 88 12" Subwoofer Box 12" Pioneer Subwoofer 800 Hz Horn 18" Eminence Woofer Ths parted high volume cabinet for dual voice coil subwoofers. Box comes with pre-cut wooter and port holes. Cabinet volume: 2 cu. ft. with dual ports. Charcoal carpet. Dimensions: 13" (H) x 13" (D) x 30" (W). Net weight: 29 lbs. #RJ-260-495 $59 90 Each 12" Pyle Woofer tfc * pyLE 12\ 70 oz. magnet woofer. 2-1/2" voice coil. 105 waits RMS, 155 watts max power handling capability. CD pioneer 12 - super duly, dual voice coil subwoofer. 30 oz. magnet, 2" voice coil. 100 watts RMS, 145 watts max power handling capability. 6 ohm impedance (4 and 8 ohm compatible). Sensitivity: 89dB1W/1M. Response: 25-700 Hz. QTS= .31 , VAS= 10.3 cu ft. Nat weight: S lbs. Pioneer #A30GU30-55D. #RJ-290-145 $39*° $36 80 (1-3) (4-up) 5-1/2" Cone Midrange Original Sanyo high end system midrange. Largs 5" paper cone with gold look dust cap. Heavy 12 oz. magnet. 1 H terro fluid cooled voice coil. 50 watts RMS, 75 watts man, Sanyo part #S12H10. Net weight: 1-1/2 lbs. Pieso mid range/tweeter driver unit- Response: BOO -20 KHz. Power handling capability: 20-30 volts (approximately 50 watts RMS). Sensitivity: 93 dB, 2.83W1M. 4" round. Motorola #KSN1Q86. #RJ-270-085 $25 30 $23 (1-3) (4-up) 95 Professional driver for use in auditorium and studio sound systems. Giant 100 oz. magnel. 250 watts RMS, 350 watts max power handling capability. fs= 30 Hz, QMS= 3.17. OES^. 373. QTS= .33, VAS= 105 cu ft. SPL=95dB1W/1M. Net weight: 29 lbs. I EMINENCE #RJ-290-200 $99 80 $93 40 (1-3) (4-up) #RJ-292-050 $62 M (1-5) $59 80 (6-up) #RJ-281-100 S4SVD $5- $3 95 Subwoofer Crossover Network Super duly. 200 wati RMS power handling capability . Designed specially for dual voice coil subwoofer systems. 12 dB per octave roll-off al V*^ 150 Hz into Sohms. Crossover also features a set of oulputs for use with your existing speaker system. Network Is totally passive, requiring no power source ol its own. #RJ-260-220 (1-9) (10-up) $28 80 (1-5) $24 95 (6-up) ///-Parts //express 340 E. First St., Dayton. Ohio 45402 Local: 1-513-222-0173 FAX: 513-222-4644 CALL TOLL FREE ■15 day money back guarantee • £15.00 minimum order « We accept Mastercard. Visa. Discover, and C.O.D. orders. * 24 hour shipping * Shipping charge - UPS chart rate + S1 .00 (S3.00 minimum charge) ■ Hours 8:30 am - 7:00 pm EST, Monday- Friday • 9:00 am- 2:00pm Saturday, Mailorder . nnn nnn riCOH customers, please call for shipping estimate on orders exceeding 5 lbs. | "0UU"00O"UD*Jn Foreign customers please send S5.00 U.S. lunds for catalog postage. FREE CATALOG ^ CIRCLE 56 ON FREE INFORMATION CARD WANTED INVENTIONS/ new products ideas wanted; call TLCI for free information 1 (800) 468-7200 24 hours day - USft'Canada. INVENTORS: We submit ideas to industry. Find out what we can do for you. 1 (800) 288-IDEA NEED help with your electronic project, PCB as- sembly artwork? Write to T.S., PO Box 5275, Flint, Ml 48505. I'LL HAVE MINE DESCRAMBLED P 9^ If you find a better deal, We'll beat itl JERROLD • TOCOM • HAMLET • OAK • SCIENTIFIC ATLANTA ■ ZEMTTH • ask about our warranty program C.O.D. Visa, M/C, AM, EX. welcome. • FREE CATAUDG • FREE CALL •OPEN SATURDAYS 1 800 562-6884 VIDEO TECH 3702 S. Virginia St, Ste, 160-304 Reno, NV 89503 INVENTORS! Your firsl step is important. For free advice, call ADVANCED PATENT SERVICES, Washington, DC, 1 (800) 458-0352. TRAVEL! High income! Radio officers wanted for shipboard employment. Must have FCC second telegraph license. Rae Echols, AMERICAN RADIO ASSOCIATION, 5700 Hammonds Ferry, Linlhicum, MD 21090 WIRELESS RCA FM mike, oldstyte, with dangling antenna, for parts Collect (416) 499-6367. FREE CATALOG! 1-800-648-7938 JERROLD HAMLIN OAK ETC CABLE TV • Special Dealer Prices! ■ Compare our Low Retail Prices! • Guaranteed Prices & Warranties! • Orders Shipped Immediately! REPUBLIC CABLE PRODUCTS, INC. 3 4080 Paradise Rd. #15, DeptRE791rn 3 Las Vegas, Nv 89109 C~2~J For all other information (702) 362-9026 BUSINESS OPPORTUNITIES MAKE $50. hr working evenings or weekends in your own electronics business. Send for free facts. MJME INDUSTRY, Box 531, Bronx. NY 10461-02CB. YOUR own radio station! AM, FM, TV, cable. Li- censed unlicensed. BROADCASTING, Box 130- F7, Paradise, CA 95967. EASY work! Excellent pay! Assemble products at home. Call for information (504) 641-8003 Exl. 5192. MAKE SSS! Become an American electronics deal- er! Profit opportunities since 1955, Call SCOTT PRUETT, 1 (800) 872-1373, n i i i i ;n Great money in VCR repair! Home study. Learn high-prolrt repairs with out investing in higMech instruments. >^A\ m FREE BOOKLET: 800.223-45.12. Name . R ■ Address w - V I City State Zip The School of VCR Repair, 2245 Perimeter Park, Dept-VG342. Atlanta, Georgia 30341 iTJ LET ihe government finance your small business. Grants loans to S500.000. Free recorded message: (707) 449-8600. (KS1). MAKE 575,000 lo $250,000 yearly or more fixing IBM color monitors (and mosl brands). No invest- ment. Start doing it from your home. (A telephone required.) Information. USA, Canada S1.00 cash. US funds other countries $8.00 RANDALL DIS- PLAY, Box 2168-R, Van Nuys, CA 91404 USA, ELECTRONIC ASSEMBLY BUSINESS Start home spare time. Investment knowledge or experience unnecessary, BIG DEMAND assem- bling electronic devices. Safes handled by profes- sionals. Unusual business opportunity. FREE: Complete illustrated literature BARTAREOrjBux248 Walnut CieeK Call I 94597 ZENITH & TOCOM SPECIALS SUPER Zenith (Z-TAC) converters (flashing). . $179.00. Zenith "turn-on" module... 349.00. Tocom 5503(A) converters... $159,00. Tocom (add-on) descramblers... $79.00. Tocom (5S03-V1P & 5507) "turn-on" chips... $49. 00 Tocom 5507 se- curity screw removal bits.. .$22.00, CINEPLEX VID- EO GROUP, 1 (800) 726-4627. CHOOSE FROM THE FOLLOWING PACKAGES: PKG. # 1... ■j ft PANASONIC $CC E IU 1453G CONVERTERS Y Uw. PKG. *2... 8 SCIENTIFIC ATLANTA 8535+ COMBINATIONS $175 PKG. 3... 5 SCIENTIFIC ATLANTA $91 E" 8580 COMBINATIONS V 4lv. PKG.*4... ifl MIX AND MATCH ADO-ONS $45" ALL EQUIPMENT IS BRAND NEW, FACTORY FRESH !!! (800)234-1006 CA|L||HIIlf Cable Descramblers New Auto Tri-Bi guaranteed no Hashing $165.00 ZENITH SUPER SAAVI S199.00 TOCOM 1319.00 EAGLE $119.00 COPY GUARD SS9.9S 5TARCATE 2000,,, SS8.00 SB-3 $99.00 TRIMODE SlW.tXl HAMLIN S99.00 SCJENTtFlC- ATLANTA $119,00 OAX M35B... $99 00 ZENITH $175.00 M.D. Electronics will match or beat any advertised wholesale or retail price. Your best buys and warranties for cable converters and descramblers start with a FREE catalog from MD For Information Call 402-554-0417 To order or request a free catalog 1-800-624-1150 EXCELLERATOR CABLE CONVERTERS WHEN QUALITY COUNTS New Dynatrick™ fine tuning provides unmatched picture quality S50 Mhz tuner provides 83 channel capacity Sleep timer for automatic shut off within 15-90 minutes 2/3 swilchable I1RC I IRC / Standard Sivilchable 2 Year warranty, l^ast channel recall, I : avoriic channel select. Scan Double vented high efficiency transformer Tor cool performance Siargate-2001 $99.00 Stargate-550XL $119.00 With Volume Control Don't settle for anything less. *£${ (S c.o.d. > arra so. 7Znd s*. Omaha, NE6SM lYOMMtKTOlM.i TV tCCTHINT FICHU D. VUCTKNICSTHinilDUSElt AGREES TO COMPLY WIT1 [ ALLSTATS AN D FECCKAL LAWS XECARDfNC PRIVATE OW^TgSniTCf CAUiTV BQUITMET. IF YOU AXE UW UK OF THESE LAWS OISCK Wmt TOLTL LOCAL OFFICIALS. CIRCLE 53 ON FREE INFORMATION CARD CABLE T.V. DESCRAMBLERS BASE BAND ■ ■■« _ $399.00 Starcom 7 DQN7V S120.00 TR1M0DE $119.00 ZENITH 1086.S249.O0 DQN7 $99.00 SA8580 S299.00 SB3 SS5.99 PIONEER S399.00 JERROLD DRXS99.00 MANY MORE ...CALL OR WRITE FOR FREE FAST INFORMATION. YOUR BEST BUrS & WARRANTIES FOR CABLE CONVERTERS AND DESCRAMBLERS START WITH A FREE CATALOG FROM: WORLDWIDE CABLE 7491 C-5 N. Federal Hwy, Suite *14Z Boca Raton, FL 33487 ORDERS AND CATALOGS CALL TOLL FREE 1-800-772-3233 L^rCo*) C.O.D. BY ORDERING CABLE TV EQUIPMENT FROM WORLDWIDE CABLE THE PUR CHASER AGREES TO COMPLY WITH All STATE AND FEDERAL LAWS REGARDING PRIVATE OWNERSHIP OF CABLE TV EOLITOIENT. IF YOU ARE UNSURE OF THESE LAWS CHECK WITH Y0LTR LOCAL OFFICIALS. CIRCLE 184 ON FREE INFORMATION CARD FREE CATALOG! 1 .800-348-7659 ELECTRONIC COMPONENTS. AUDIO, VIDEO, TELEPHONE. ANTENNA & ACCESSORIES. PiY-rji Cdp 20 {^wakH Ha PO Ite. 1KJ3. Era B*b-aft<* NJ Q»iE> Video Transceiver Digital Video Stabilizer i 1 >m wtr ovm iwn nonM M tm a- s 55 9S J 28" s 36 9 ? BUY BONDS 7 * * * * PRESENTING * * * * CABLE TV T ***** STARRING ***** JERROLD, HAMUN, OAK iND OTHER FAMOLIS MANUFACTURERS • FINEST WARRANTY PROGRAM AVAILABLE • LOWEST RETAIL I WHOLESALE PRICES IN US • ORDERS SHIPPED FROM STOCK WITHIN 24 MRS. • ALL MAJOR CREDIT CARDS ACCEPTED FOB FBif CATALOG ONUT 1-8O0-34S-S927 FOR ALL INFORMATION 1-81B-7 09-99 3 7. PACIFIC CABLE CO.. INC. 7325V; Reseda Blvd., Dept.2104 Reseda. CA 91335 CABLE TV "BOXES" Converters — Descramblers Remote Controls — Accessories * Guaranteed Best Prices * * 1 Year Warranty— COD. s » * Immediate Shipping * • FREE CATALOG * Call or Write NAS/TRANSWORLD 3958 North lake Blvd.. Suite 255 Lake Park. FL 33403 1-800-442-9333 CABLE TV DESC RAMBLER LIQUIDATION! FREE CATALOGI I Hamlin Combos $44, Oak M35B $60 (mill. WEST COAST ELECTRONICS For Information: 818-709-1758 Catalogs & Orders: 800-628-9656 PAT TV AND SATELLITE DESCH AMBLING AILNEW1991 EDITION 0lt bKi yet The ««ry latest m d est ram Wing nrcuisj. bypasses, jikthhss lor cable. wireless ana utnlMa. Only SM.95. Olherpaj TV r*ltoon3.Vo,. t (Basics o! All S/Stems) $14 95. 1983 Edition SI *.to &u*J satellite sftima under $64$ $12.95 Wireless ftble HandQwrt S9.95. Any l-$29.35 «f 5SM.95, ScranlAirj News Manihty tus all info on trie new "Ptain VamlSa - d«cramblers which em- u=ale S- Mae. VCM PlusafrdOrion. Sl$95/yr All new caUlon, $1 Scumtiiiiiii News. 1552 Henei Aw.. Buffalo. NY, 14Z16. CODS ARE OK. 17161 871 20BS SOLDERLESS PROTOTYPING BOARDS STEEL ENCLOSURE SERIES FEATURES •Color coordinates for easy recognition •Insertion wire: 20-29 AWG (0.3 - 0.8 mm) •Over 10.000 insertion cycles ■Accepts all slandard components DDO SB830 SB1660 SB3320 EasyTech; Order # I SB200 SB-100 SB630 SB830 SB1360 SB 1660 SB2390 SB 3220 Price 1-9 2.99 4,89 5.49 6.49 12.49 17.49 22.49 31.49 Price 10+ 2.49 4.39 4.99 5.99 11.99 16.99 21.99 30.99 Dimensions (in.) LxWxH 6.5 x .37 x .4 3.3 x 2.2 x .4 6.5 x 1.4 x. 4 6.5 x 2. 2 x. 4 8.5x3.9x1.2 8.5x5.1 x1.2 9.1 x 6.9x1.2 9.5x8.3x 1.2 Dist. Strips Dist. Points 100x2 100 200 100 4O0 500 700 Term. Strip s Term. Points Binding Posts 300 630 630 1,260 1.260 1.890 2.520 FEATURES •Ventilation holes •Self-adhesive feet included •Front & rear panels: 1.3mm Aluminum Alodine (Painted White) •Top & bottom covers: 0.9mm Ptiosphated Slee] (Painted Black) Order # 1-9 10* DimenslonsfWxDxH ) E3119A 12.95 11.95 8"x7"x2.5" E3119B 15.95 14.95 12"x7-x2,5" E3119F 19.95 16.95 17 - x1 1"x2.5" E3119G 13.95 12.95 8"x7"x3.5" E3119K 24.95 23.95 17"x11"x3.5" E3119P 29.95 28.95 17"x11"x5.2" EPROMS Order tt Price TMS2532 6.95 2708 4.75 2716 3.45 2716-1 3.95 2732 3.95 2732A25 3.45 2732B45 4.25 2764-25 3.75 2764A25 3.25 27C64A15 3.75 27128A25 3.95 27256-25 4.75 27256-30 3.45 27C512-15 6.95 Proq. 25V 25V 25V 25V 25V 21V 12.5V 21V 12.5V 12.5V 12.5V 12.5V 12.5V 12.5V DRAMS Order # Price MK4027N2... .75 4116-20 85 4416-12 2.25 4164-10 1.95 4164-15 1.75 4164-20 1.25 41464-12 2.75 41256-80 2.75 41256-12 2.15 41256-15 1.95 5142S6-80....8.75 514256-10... 7.95 511000-80....8.75 511000-10... 8.25 Desc. 4x1 16x1 16x4 64x1 64x1 64x1 64x4 256x1 256x1 256x1 256x4 256x4 1Mx1 1Mx1 STATIC RAMS Order # Price 2101 1.65 2114L25 1.15 2147-3 3.75 2148-3 1.95 2149-35 3.75 5101 3.95 6116LP3 2.95 6116-3 2.45 6264LP10 4.95 6264LP15 3.95 6264-10 4.75 6264-15 3.75 62256LP10 ...7.95 62256LP15 .6.95 MICROS Orde r # Price 8031. 3.55 8080A 2.75 8085A 2.95 8086 4.45 8088 4.25 8237 A5 4.15 8250 5.75 8251 A 2.25 8253 1.95 8253-5 2.25 8255 AS 2.75 8259-5 2.25 8275 18.95 8284A 2.25 Extensive range of parts & components in stock Call to reserve your copy of our new 1991 catalog due in late July Ui»JW4W*lflf4.*MII.WJ 2917 Bayview Drive-Fremont, CA 94538 Order Direct: 1-415-770-2345 Fax Direct: 1-415-770-2346 Monday- Friday, 7am - 5pm (PST)/10am-8pm (EST) [3 VISA [7] MasterCard | "V | COD-No personal checks, US funds ($5,00 Charge) |T| USPS |T|UPS |T| Airborne Express Add 5% of total for shipping charges (S3 .00 min.) CIRCLE 177 ON FREE INFORMATION CARD We Have QUALITY PARTS • We Have DISCOUNT PRICES • We SHIP FAST mmm&mm® GEAR MOTOR Everest 3 Jennings 24 W series High torque permanent magnet gaarhead motor wilh replaceable brushes, t ■■ { th, Rated lor 24 Vdc; operates tine on 12 Vdc. We think these were originally built lor wheelchairs. 1/2" dual shall on Una) drive. Ratings: 12 Vdc 1.7 amps 220-290 rpm 24 Vdc 2,0 amps 445-470 rpm Motor is 5 374- long X 3" diameter wilh 3.1 25" square mounting bracket. Gear box is 3.37" long X 3.2' wide. Snails extend 0.75" lo either side ol near box. 9,5 bs. CAT* MOTG-16 $25.00 each TOUCH DIMMER 12 Vdc POWER PACK FLOURESCENT FIXTURE The "brain part of the 'LITE TOUCH" touch when connected to any lamp, wlH turn H on and of- and change the brightness level when any metal part is touched. We dont have the Wiring harness thai originally connected this to the lamp, but we can provide a simple hook-up diagram and instruction sheet. The solid-state circuitry is contained in a thermo- plastic box 1,91" X 3.1 r X 0.835". CAT#DMR-t $3.50 each 12 Vdc 1 Amp. power pack. 8 ft. 2 conductor pwoer cord on input. 22" cord wilh stripped and tinned pigtail leads on output. 3,2" X 2,3" X 1 .9". CAT#DCTX-121 $5.75 each ,I&JS% Fixture for single mini bi-pin 6", A watt fluores- cein ; lamp. Starter switch, sockets and ballast are mounted on 7 1M" X 3 1/4" metal plais. Includes 8 fool power cord with strain relief. Use with standard fluorescent tamp lor display lighting or with ultraviolet lamp Tor special ef- fects or EPROM erasure, U.L listed. CATflFUM M.OOeach SWITCHES Dip P.C. Pushbutton ITT Schadow Dlgfiast Series SE S.P.D.T. momentary pushbutton. Mounts in 14 pin DIP conliguralion. Designed tor low current switching appli- cations. Grey keycap is 0.63' X 0.67". CATHPB-28 J 1.00 each 10 lor $9,50 • 100 tor 185.00 Pushbutton Switch SMK Manutacturing 0.47" square black pushbutton. SPST normally open. 4 p.c pins for mounting. Ideal tor low current switching applications. CAT* PB-29 5lor$1.0O-10Q tor 115.00 Rotary BCD Switch r~ \ EECO - 2310-02G I iSa BCD reposition V— ^ rotary switch. DIP configuration fits in standard 8 pin I.C. socket. Flight angle style. Screwdriver actuation. 0.42" cube. CAT#R0IP-2 $1.75 each 10for $16.00- TOO lor 1145.00 Miniature Toggles Rated: 3 amps @ 120 Vac S.P.D.T, (Off-ON) PC. mount CAT#MTS-4PC Si. 00 each g 1 tor $9. 00 - 1 0Q lor $80.00 J S.P.D.T. (ON-OH) solder I ugs to C AT* MTS-4 $ i .35 each Rf) 10 lor J1 2.50- 100 for S1 10.00 nV D.P.D.T, (ON-ON) solder lugs CAT* MTS-8 $1.75 ea, I0for$l5.00 D.P.D.T. (OH-ON) P.C. mount CAT#MTS-aPC $2.00ea, I0lor$17.50 TELEPHONE KEYPAD PH0T0FLASH CAPACITOR HALL EFFECT SENSOR P.C. RELAYS Rubicon G£ 210 Mid 330 Volt pholoflash capacitor. 0.79" dia. X 1.1" high. These are new capacitors that have been prepped wilh 1.4" black and red wire leads soldered to the terminals. CAT* PPC-210 SI .25 each- 10 lor $11.00 100 lor $100,00 Large quantities available. Call for pricing. RECHARGEABLE BATTERIES 6 Volt 1 Amp/Hour Japan Storage Saner/ Co, Portalac # PE6V1 6 Volt 1 Ah rechargeable J sealed lead-acid ^—^ —J/ (gellceirj. 2" X 1 .635" X 2" hi. Batteries are propped with 5" black and red leads terminat- ed with 2 pin connector. CAT*GC-61 $4.75 each 10 lor $42.50 Nickel-Cad L> Hicf0Switch#SS4i Tiny, solid state switch reacts instantly to proximity of magnetic Held, Operates at extremely high speeds, up to 100 khz. Case size: 0.12" X 0.17" X 0.06* thick. 4.5 Vdc to 24 Vdc supply voltage. 10 ma. sink type digital output. Operating gauss ■ 15 to 40. P.C. leads. CAT* HESW-2 75c each - 1 for S6.5G 100 lor 560,00- 1000 lor 5500.00 3 1/2" DISKETTES QuaJhy. double-sided 3 1/2" diskettes. These diskettes were recorded. bul never used. Flip the write -protect tab to of! position and use tor your own data storage at a fraction of the cost of new diskettes. CAT*DTS-1 $1.00 each * 10 lor 59,00 AUDIO SLIDE POT Dual IK audio. 3 1/2" long, 2 1/2" slide CAT*ASP-tKD Reduced to 50c each 100 for $40.00 I.E.C. POWER CORD 12 button telephone keypad. Ivory finish. 2.83" x 2.2" x 0.58' thick. Matrix encoded. Ideal for telephone or security keypad. CAT * KPT-1 $1 .00 each fEtf: 10 for $9.00 OPTO-SENSOR TRVWOplron I OP85447-2 IR emitter/sensor pair in Rectangular package with 28" color coded leads. CAT»OSR-4 2lor$1.00 AAA SIZE $1.50 each 1 .2 volts 1 80 mAh CAT* NCB-AAA AASIZE $2.00 each 1.25 volts 500 rrtAh CAT* NCB-AA AASIZE $2.20 each WITH SOLDER TABS CAT* NCB-SAA C SIZE $4.25 each 1.2 volts 1200 mAh CAT* NCB-C DSIZE $4.50 each 1.2 volts 1200 mAh CAT* NCB-D G loot BLACK. SPH-386 jack to 3 prong molded A.C, plug. Fits most computers, computer terminals and lest equipment. CAT#LCAC-C6 $3.00 each FLASH ASSEMBLY New compact Hash \ J Utility component box ■ 6 piece precision screwdriver set • 6' long tweezers ■ 8 piece hex hey wrench set • T brush and scraper • Digital Mulli meter • Brush ■ 7" line point probe • Round needle tile • 10 piece screwdriver set: S Slotted & 4 Phillips • 7" slotted probe ■ Hat needle tile ■ 4.5" diagonal culling pliers MS305 $119.95 Global Specialties Protoboard® Design Station 6" adjuslable wrench 30 Walt soldering iron 5.5" Stainless steel Soldering stand Rosin core solder 5.25" Flal nose pliers Utility knife wilh extra blade Desoldering pump 5.25" Bent needle nose pliers Carrying case: 17.63-Wx12.5-Dx3.5-H Jameco Logic Pulser • Compatible wilh TTL. DTL. RTL, HTL, HNIL. MOS and CMOS (OS, - IMC] Sync tnpul impedance ■ Pulser mode output current: 10mA ■ Square wave current oulpul: 5mA * Audible lone LP540 $16.95 Jameco Logic Probe PROTOTYPING PRODUCTS Jameco Solderless Breadboards Ptri Dim, Cnnlacl Binding No. L" I W" Polnli Poses Price JE21 325x2.125 400 S4.S5 JE23 6.5 x 2.125 836 $6.35 JE24 6.5 x 3.125 1.366 2 $12.95 JE25 6.5x4.25 1.660 3 $17.95 JE26 6.675x5.75 2.390 4 $22.95 JE27 .1 7 25x7.5 IAIV 3.220 IE( 4 $32.95 :o 24 Hour Order Hotline (415)592-8097 FAX: (415) 592-2503 (415)595-2664 ■ Max Frequency BOMHz ■ Minimum delegable pulse: 10ns - 120KU inpul impedance ■ Max. supply vollaoe: :25V ■ TTL threshold: (Lo)*0,8V :0.1V (Hi) .2.3V :D.2V • CMOS threshold; (L0)30% VCC tt(M4 (Hi) 70WCC t10% MS104 $24.95 Met ex Digital Multimeters General Specs: * Handheld, high accuracy . AC/DC voltage, acdC current, resistance, diodes, continuity, transislor hFE ■ Manual ranging w/ overload projection M3650 & 1,11650 only: . Also measure frequency and capacitance M4S50 only: ' Data hold switch -4.5 digit M3 6 1 ;-.;•:;: r.' .!■-.■:■■ ■ $59.95 MS 650 3 .5 Dion Muldmeler ^'Frequency S Capacitance ........... ,.S74 . 95 M4650 i 5 Digil hi Frequency, Capacitance and Data How Smlch $99.95 Handheld Multimeter Features: • Ideal for analog, digital and microprocessor circuits • Triple DC regulated power supplies. +5V, +15V,-15V -3 logic indicators ■ Function generator with sine, square, triangle and TTL waveforms • Two debounced push- button switches • Two SPDT slide switches, all leads available and uncommited • A total ot 2520 uncommited tie-points - Potentiometers: one 1 K£2 and one 10KIJ • Includes power supply, instrumentation and breadboarding PB503 $299.9 A.R.T. EPROM Programmer - Programs all current EPROMs in the 2716 to 27512 range plus the X2864 EEPROM •RS232 port ■ Software included EPP $199,95 UVP EPROM Eraser ■ Erases all EPROM's • Erases 1 chip in 15 minutes and S chips In 21 min •UV intensity: 6800 UW/CM 2 DE4 $89.9J E PRO Ms - for your programming needs Part No. Price .«*-- ■ 3.5 digit LCD wilh automatic polarity indication + AC/DC vollage measurement up 10 500 volts ' AC.'DC current measurement up to 2Q0mA ■ Resistance measurement up to 20M11 ■ Con- tinuity checker wilh audible tone « Diode and logic tester ■ Aulc'manual range and data hold funcltons ■ Afl 19S1 Jameco Elecironics 7/91 CA Residents Add 6.00%, 6.50% or 7,00% Sales Ta* Shipping, handling and insurance are additional. (Costs may vary according [o weight and stepping oietno<1} Terms: Prices suhject lo change without notice. Items subiecl to availability and poor sale. CompJple ml 04 rerms*flrrami«* is available upon request l&M i» a *«g.?lBiK) lrj»m»A o! UiUfnauanal &J3.^«S1 Matninai visa MMC Customer Service 'Technical Assistance * Credit Department ■ All Other Inquiries • (41 5) 592-8097 • 7AM - 4PM P.S.T. CIRCLE 114 ON FREE INFORMATION CARD 5 ID to 93 3 FORI SPECIAL ON SUB-MINIATURE VOICE FM TRANSMITTERS. KITS CONTAIN PC BOARDS ■FMX-1 LONG RANGE (3 Ml) ULTRA SENSITIVE FM VOICE XMTR with fine tune, range control plus ..S34.50 •TELX-1 TELEPHONE FM XMTH (3 Ml) auto- matically operates when phone is used. Crystal clear clarity with fine tune and range control. Non detectable S34.50 'ATR-1 AUTOMATIC TELEPHONE RECORDING DEVICE tapes telephone conversation all automatically $19.50 ALL THREE OF ABOVE FOR S69.50 CALL OR SEND VISA. MASTER CHARGE. MONEY ORDER, ETC. TO AMAZING CONCEPTS, BOX 716, AMHERST. NH 03031. (603) 673-4730. THE ELECTRONIC GOLDMINE o z o rr F o UJ O Q < rr 94 Till ElictroTlEt GoHmiM I tescne cri Lie Arabs se- \ Ipciigns til inicpja dEtiratic 1 kjLs available in the wjrtfj Wa rs« on f30 ' kits a^p-p 1.400 unique, bargain ' priced, mmpwentj i'- ::■■..' C3B rjj! OlfFEBtm I rrr mouse PiK'fian Bictse matte Fur Ite ITT XHW pascal oaffiEajw. Snipped tampicia with able, to* con&irinQ dttai board, mouse, sodware QcskEil! and iranial. 6 c 00 GS1$ VJ- INFRARED DETECTOR KIT Grui irx tesiing and vtriiicgior- cr i-diaiM OLipJ. Uses senjlrv? sutsor and i.Kiran.: tittulry id rtwti to a" typs at wtafid TV. VCR. et rente mrsiolfeis and LED5 prtdudrq sound and BoMSorj 1 thai red LED. 9/ bacsnj (not indudBlJ. Size rf hoant ZJ" k 1-4". CompUa wWi HI pats, PC board anct Ingnjctions C644 1 S5.95 ULTRASONIC PEST REPELLER KIT - According & re- agri* low -JE-i-lj- ufirasonic sound WrQ .fpft! PSS31 and small rodsnts The output di r ii;l Is obnaoticm id tne Eii!. t>j a atxM Ite hear Ing range ol iinarE. oo£S. Q&. and inH .?.' cai^ (no I inetuted). Sat d toit is - * r. Comcjtt w:h ai parts. PC bow) a«l InanctiFK. C635Q $-9-00 4KV TRIGGER COIL ^% 'UB wflh any SliOtK tuts ttsl need! a 3 fead 4KY trigger N.L70Q S1.2S EA. 100 1=f S80.0Q INVERTER TRANSFORMED SniaU 4 lead iraniionntf fa wse nAh 555 IC lo comet IMC a 250V lor sratertbjoiccerf lutes frilh screnafc SI 70S S2,00 FA io In sis.oo STROBE TUBE & SCHEMATIC^?] MM lube fef[ making | ( noteUgii Wwes ffihtnaic sfnwiflc fiJ lute and uccc ml snown a sit Sfflo lute IS GW6 si,» n nosn i'js ULTRAVIOLET SENSOR SUN EXPOSURE METER Small .iSttt iic device deaca HV Energy Irom tse sun ard sounds a. s'fjrvu when you"* tad Ercujn ewsijt. 2 <&& tor skin type and an screw raing [SPT). uses IC praTi-y and saeclal LTV sensor. MsemblEd and ready Id ga, Uii; new smlus iitm is now awlabfc at a fraction ol ire oripjrol cofl. (najjira W tBEsy. xl LTc-jded.) G934 $8.95 MINIMUM ORDER: S 1 01.1 i&lS $300 Sli-pptrq- 3J*j hu3f»0Tino Wo accept MC. Visa and Money Orders. SEND ORDERS TO: TTie Elector*; GoUftUW P.O. Sox 5-iOa Scoisdaia, AZ aG2Ci PHONE ORDERS {602] 4S1-T454 FAX ORDERS [&02> 4S1-94QS CIRCLE 178 ON FREE INFORMATION CARD ADVERTISING INDEX RADIO-ELECTRONICS does not assume any responsibility for errors that may appear in the index below. Free Information Number Page HIS 181 75 107 84 98 109 189 58 176 127 177 178 121 183 86 114 115 87 53 93 61 117 56 78 AMC Sales 46 Ace Communications IK Ace Products 21 All Electronics 91 Amazing Concepts 87. 94 Appliance Service 21 licckniiiri Industrial 9 C&SSales 17 C1E 5.25 Cable Ready Company 89 Cable Warehouse 75 Command Productions 9 Cook's Institute 16 Damark International II Datak Corporation -. . . 29 Deco Industries 21 Digital Engineering 88 EasyTcch 90 Electronic Goldmine 94 Electronics Book Club 7 Electronics Engineer B.C 8(J Fluke Manufacturing CV2 General Technics 21 Global Cable Network 85 Grantham College 75 Heathkit 73 ISCET 10 Jameco 92 . 93 Jensen Tools 21 MCM Electronics. 87 MD Electronics 89 Mark V. Electronics 85 Microprocessors Unlid 79 Mouser II NPEC 27 NRI Schools 12 Parts Express 88 Perfect Cable H6 Radio Shack 30 RE Video Offer CV3 185 SCO Electronics 16 180 Sencore CV4 — Star Circuits 28 92 Tektronix 3 1 23 Test Probes 46 The SPEC-COM Journal ,10 188 Unicorn 84 186 U.S. Cable 16 187 Vitjo Publications 46 179 WPT Publications 76 — Wholesale Cable S8 184 Worldwide Cable 90 ADVERTISING SALES OFFICE Gems back Publications, Inc. 500. B Bi- County Blvd. Farmingdale, NY 11735 1(516) 283-3000 President: Larry Steckler Christina Estrada assistant to the President For Advertising ONLY 516-293-3000 Fan 1-516-293-3115 Larry Steckler publisher Arline Fish man advertising director Denise Ha wen advertising assistant Kelly McQuadc credit manager Subscriber Customer Service 1-800-288-0652 Order Entry for New Subscribers 1-800-999-7139 7:00 AM -6:00 PM M-F MST SALES OFFICES EAST/SOUTHEAST Stanley Levttan, Eastern Sales Manager R ad io - E lectroni c s 259-23 57th Avenue Little Neck. NY 1 1362 1-718-428-6037, 1-516-293-3000 Fax 1-718-225-8594 M I D W EST/Texa s/ Arka nsas/Okla. Ralph Bergen. Midwest Sales Manager Radio-Electronics 540 Frontage Road — Suite 339 Northfield, IL 60093 1-708-446-1444 Fax 1-708-446-8451 PACIFIC COAST/Mountain States Marvin Green, Pacific Sales Manager R a d i o - E lectron i c s 5430 Van Nuys Blvd. Suite 316 Van Nuys.CA 91401 1-818-986-2001 Fax 1-818-986-2009 RE Shopper Joe Shere. National Representative P.O. Box 169 Idyllwild. CA 92349 1-714-659-9743 Fax 1-714-659-2469 Countersurveillance Never before has so much professional information on the art of detecting and eliminating electronic snooping devices — and how to defend against experienced information thieves — been placed in one VHS video. If you are a Fortune 500 CEO, an executive in any hi-tech industry, or a novice seeking entry into an honorable, rewarding field of work in countersurveillance, you must view this video presentation again and again. Wake up! You may be the victim of stolen words — precious ideas that would have made you vety wealthy! Yes, profes- sionals, even rank amateurs, may be lis- tening to your most private con- versations. Wake up! If you are not the victim, then you ate surrounded by countless vic- tims who need your help if you know how to discover telephone taps, locate bugs, or "sweep" a room clean. There is a thriving professional service steeped in high-tech techniques that you can become a part of! But first, you must know and understand Countersurvei lance Technology. Your very first insight into this highly rewatding field is made possi- ble by a video VHS presentation that you cannot view on broadcast television, sat- ellite, or cable. It presents an informative program prepared by professionals in the field who know their indusrry, its tech- niques, kinks and loopholes. Men who Can tell you mote in 45 minutes in a straightforward, exclusive talk than was ever attempted before. Foiling Information Thieves Discover the targets professional snoopers seek out! The ptey are stock brokers, arbitrage firms, manufacturers, high-tech companies, any competitive industry, or even small businnesses in the same community The valuable informa- tion they filch may be markering strat- egies, customer lists, product formulas, manufacturing techniques, even adver- tising plans. Information thieves eaves- drop on court decisions, bidding information, financial data. The list is unlimited in the mind of man — es- pecially if he is a thief! You know that the Russians secretly installed countless microphones in the concrete work of the American Embassy building in Moscow. They converted CALL TOLL FREE 1-800-522-6260 HAVE YOUR VISA or MC CARD AVAILABLE what was to be an embassy and private residence into the most sophisticated re- cording studio rhe world had ever known. The building had to be totn down in order to remove all the bugs. Stolen Information The open taps from where the informa- tion pours out may be from FAX's, com- puter communications, telephone calls, and everyday business meetings and lunch time encounters. Businessmen need counselling on how to eliminate this in- formation drain. Basic telephone use cou- pled with the user's understanding that someone may be listening or recording viral data and information greatly reduces the opportuniry for others to purloin meaningful information. RADIO- ELECTRON 1C5 V [ DEO OFFER RE 500-B Bi-County Blvd. Fatmmgdale. NY M7*5 Please rush my copy of the Coumersurvei I lance Techniques Video VHS Cassetur far $49-9) plus *4. 00 ft>r postage and handling No. of Cassettes ordered Amount of payment & Bill my D VISA □ MasterCard Catd No. Expire Date / Signature . Name Address City . State . .ZIP . All payments in U.S.A. funds. Canadians add $4.00 per VHS cassette. No foreign orders. New York State residents add applicable sales tax. The professional discussions seen on the TV screen in your home reveals how to detect and disable wiretaps, midget radio-frequency transmittets, and other bugs, plus when to use disinformation to confuse the unwanted listener, and the technique of voice scrambling telephone communications. In fact, do you know how to look for a bug, where to look for a bug, and what to do when you find it? Bugs of a very small size are easy to build and they can be placed quickly in a matter of seconds, in any object or room. Today you may have used a telephone handset that was bugged. It probably contained three bugs. One was a phony bug to fool you inro believing you found a bug and secured the telephone. The sec- ond bug placates the investigator when he finds the real thing! And the third bug is found only by the professional, who continued to search just incase rherewere more bugs. The professional is not without his tools. Special equipment has been de- signed so that the professional can sweep a room SO that he can detect voice-acti- vated (VOX) and te mote- activated bugs. Some of this equipment can be operated by novices, or hers require a trained coun- tersurveillance professional. The professionals viewed on your tele- vision screen reveal information on the latest technological advances like laser- beam snoopers that are installed hun- dreds of feet away from the room they snoop on. The professionals disclose that computers yield information too easily. This advertisement was not written by a countersurveillance professional, bur by a beginner whose only experience came from viewing rhe video rape in rhe pri- vacy of his home. After you review the video carefully and understand its con- cents, you have taken the first important step in either acquiring professional help wirh your surveillance problems, or you may very well consider a career as a coun- tersurveillance professional. The Dollars You Save To obtain the information contained in the video VHS cassette, you would attend a professional seminat costing $350-750 and possibly pay hundreds of dollars more if you had to travel to a distant city to attend. Now, for only $49.95 (plus $4.00 P&H) you can view Countersur- veillance Techniques at home and take refresher views often. To obtain your copy, complete the coupon below or call toll free. Isolate These And Other Major Components InAllTVsAndVCRs- Guaranteed Or Your Money Back! VA62A Universal Video Analyzer Plus, Cut Your Video Troubleshooting Time By 54%* With The Patented VA62A Universal Video Analyzer! Identify tuner problems with the only integrated all- channel, VHF, UHF, and cable RF generator. Standard TV, standard cable (2-99). and exclusive programmable cable channels eliminate the question "Is it the TV or is it the cable?" Pinpoint IF troubles with modulated troubleshooting signals and exclusive programmable IF generator. 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The VA62A's patented "Ringer" and exclusive flyback drive tests allow you to completely analyze all yokes, flybacks, and IHVTs before you order a new one. Measure signal levels with a fully autoranged PPV and DCV digital meter. The VA62A's built-in meter shows when you are driving into a shorted circuit and prevents you from overdriving criti- cal stages. Plus, measure bias voltages and signal levels throughout the entire TV and VCR. It's obsolete proof: update for new technology with exclusive phase- locked accessories. We'll provide new companion units as the manu- facturers announce new formats, test patterns, etc. This makes your VA62A a protected investment. * Based on a nationwide survey of users who reported an average time savings of 54% compared to their previous test equipment. For More Details Call 1-800-SENCORE ext. 612 (736-2673) CIRCLE 180 ON FREE INFORMATION CARD