HACKING N INTENDO'S SUPER NES APRIL 1392 TECHNOLOGY - VIDEO - STEREO - COMPUTERS - SERVICE STER FOR Up to 200 watts of clean power/ per channel! / Build an intelligent PHONE-LINEl MONITOR I and keep tabs on your telephone bills e bills / the A look at the compon^ots and circuits used for llilid- iiu/aul UlL^i'iLilil r | i;iHiirj Miiii:i:iiiiir< 7-segme decoder/driver IC's $2.95 U.S. $3.75 CAN Simple circuit protects agai for your equip SERNSBACK xxxxxxxx CrtR-RT SORT s:*: CRDS 75D45GHRR5I65Ma93 D4 35 NOU 93 RE We Only Skimped OnThe Price. Introducing The Fluke Series 10 — From $69.- Actual size: Easy tocarfy, easy to use Hewt V Cbek For fast accurate checks or power sGurces and supplies, set your meter or V Chek— and let it do the resl VChek will determine contin jity/oli ms: if voltage is present, it wili automaiicBliy change modes to measure AC or DC voils. whichever is delected. For most initial Iroubfeshooting checks, here% the onfy setting you need to make. Fluke quality: Made m the tJSA by Fluke, with the same rugged reliability that s made us the world leader in digitai muliimeters. Count on hard-working high performance— and a two^year warranty to back tt up. Large, easy to-read display; 4000 count digital readout. Hmi Mffi/Max record with relative (ime stamp and Conllnulty Capture'": Makes mtermittent problems easier to find. Records highs and lov.rs_and "time stamps ■ when they occurred. In continuity mode, opens or shorts as brief as 250 [iS are captured and displayed. Capacitance: Autoranging from .001 uF to 9999 mF- No need to carry a dedicated capacitance meter For liigh performance at Fluke's lowest price, get your hands on the new Series 1D, Stop by your local Fluke distributor and feel what a powerful difference the right multimeter makes— at the rip hi price. For a free product brochure or the name ofyour nearest distributor, call l^eOO-ST-FLUKE- Mrn/Wax recording With retaJive lirriQ stamp Continufty Capture^" Capacitarvce, .001 10 9999 4QO0cDunL digital display 09^ base dc volts accuracy T.9% basarac volts Safety— a Fluke standard: Designed to meet UL1244, l£C1010.CSAandVDEsaIety requirements; extensive overload protection built in. Audible Cofilinuity: To perform fast continuity checks, just listen for the beep: no need to watch the display. The New Series 10. A Small Price For A Fluke- FLUKE AND [Mi I L I P S T I E E T & M ALLIANCE (fS'1S91 John Fiyke Ul^. Co.. Irvc, Pfic^i^nd spectficaUons sybjcct to Change. Ad no-. 00130. Hewi TL7S Hard Pom!" Test Leads: Comfort grip witii extra strong tips for extended service life. CIRCLE 121 ON FHEE INFORMATION CABD April 1992 Vol 63 No. 4 BUILD THIS 31 HIGH POWER HI-FI AUDIO AMP FOR YOUR CAR It boasts low distortion and 270-watts output power. Reinhard Metz and MyzH Boyce 37 THE SNOOPER STOPPER Filter out the cable-TV "bullet" and other signals. Edgar Wolf 47 REMOTE CONTROL FOR YOUR DOG A safe and humane way to stop your dog from barking. Fidel Canltio 52 INTELLIGENT PHONE LINE MONITOR Putting the Digi-Call together and putting it to work! Thomas E. Black PAGE 47 40 ELECTRONIC TEMPERATURE MEASUREMENT A look at some temperature- measurement circuits. Harry L. Trietley Electronic Tempera 57 BUILD THIS MICROPROCESSOR DEVELOPMENT SYSTEM This stand-alone unit for the 1 802 microprocessor can be used for training and development Dave Dage PAGE 40 6 VIDEO NEWS 70 What s new in this fast- changing field, David Lachenbruch 24 EQUIPMENT REPORTS Global Specialties Protolab 3-0 Circuit-Modeling Software 63 HARDWARE HACKER 80 Laser printer repairs, and more- Don Lanca&ter AUDIO UPDATE Hear today, gone tomorrow. Larry Klein 72 DRAWING BOARD A display driver for our oscilloscope. Robert Grossblatt COMPUTER CONNECTIONS Will you OS/2 it? Jeff Holtzman 94 Advertising and Sales OKices 94 Advertising Index 12 Ask R-E 84 Buyer's Mart 16 Letters 29 New Lit 26 New Products 4 What's News 1. CO n 1 IfyouVe been shopping aroundfor car audio amplifiers lately, you're sure to have noticed that high perfor- mance and high power are invaria- bly accompanied by high price tags. Our build-it-yourself amp is the ex- ception: It outputs 270 watts of power CI 35 watts per channel, RMS, into 8 ohms) with low distortion and high output current capabilities. Be- cause the power output is in continu- ous watts into 8 ohms, ordinary home speaker components — which are less expensive than 4-ohm speakers — can be used. And if you do opt for 4-ohm speakers* the am- plifier will deliver an astounding 200 watts per channel! For more infor- mation, turn to page 31. THE MAY ISSUE GOES ON SALE APRIL 2. BENCHTOP MULTIMETER ROUNDUP Our buyer's guide can help you choose the right DMM for your work bench. MIDI LIGHT CONTROLLER Create professional Hghtmg displays using the Musical Instrument Digital Interface. BUILD AN ELECTRONIC ALTIMETER Perfect for pilots, mountain climbers, and anyone interested in knowing the altitude. BUILD A MICROPROCESSOR DEVELOPMENT SYSTEM Construction and operating details for the 1802 microprocessor development system. At ■ lervica to f«Ad«r». RAOtO ELECTf^ONlCS publt&hcii av^ilabfe plarts or inforiniitioii re Ealing to nowsworthy produeia. t«cNi»qu«i and tciantific and l«ch'nDlo9iu3 develop rrc-nts B« causa ol pai&ible yjrtances in lh« quality and co^djt^on oi matffn«li «jvd worlirfiAi^ihtp uied by rv«d«r&. RADiO-ELECTROMJCS dctcUums any r»tp if i rector editorial production Karen Brown advttftismg produ^ion production n s s i st4tnt CIRCULATION DEPARTMENT Jaeqyellno P. Chfre&eboro ciTcotfition director Wendy Alanko circutcitton anftJyst Therei»a Lombordo circubtion a&^istant MlchoJa Torrillo, repriril bookstore Typogfaphy by Mattjs Graphics Cover photo by Divorsified Photo Services Riidl0*£t«otrottic8 is indexed m Applied Sciattca 5 Technohgy Index and Renders Guide to Periodic^t Ui^r- flture, Microfilm A MECrofiche editions are o^ailEibte, Contact circulation depart- menl for detaits. Ad¥«rtifling Sales OKices listed on 94. RiadiO'Electronics Executive and Admmtstrati^e Offices Subacribef Customer Service: 1-800 288 0652. Order Entry for New Sutucnbefs: 1 aOO 99^ 7139. <5t Cirarfaticvi — Now, You Can Eavesdrop On Tht World- Introducing the new Drake R8 Communications Receiver, It's world class, world band radio, made/in the U,S.A, From Perth to the Persian Gulf, Moscow to Mozambique, local or global, you hear events as they happen with amazing clarity. Since 1943, Drake has been setting the standards in elanronic communications - . .and then raising them. Today, there's no better shortwave receiver than the Drake R8p Out-Of^This-World Performance* The new Drake R8 has more standard features than other shortwave radios. You get wide frequency range (100 KHz to 30,000 KHz), coverage of all world and local bands, and excellent dynamic range. But you also get important features you won't find on receivers costing hundreds of dollars more. A multi- volt age power supply, Pre-amp and attenuator. Five filter bandwidtlis and s>Tichronous detector. Dual mode noise blanker and passband offset, Non- volatile 100 channel memory. All designed to give you the best reception with the least distortion. Down-To*Earth Design. The ergonomic design of the R8 gives you real ease of operation. You have convenient keypad entry, with large, legible controls. The face is bold. Uncluttered. And the liquid crystal display (LCD) is backlighted for easy reading. Try The R8, . • At Our Risk, If you're not impressed by Drake's quality, performance and ease of operation, return the R8 Receiver within 15 days and we'll refund your money in full, less our original shipping charge. For more information, or to order, call TOLL-FREE, 1-800-9-DRAKE-L Telephone orders may be placed on a major credit card, S979.00 (Shipping and handling $10 in continental U.S. Ohio residents add 6^2% tax.) Call TOLL-FREE, 1-800-9-DRAKE-l today. You can*t lose, DRAKE In touch with the world, R.L. Drake Company • P.O. Box 3006 " Miamisburg, Ohio 45342 U.S.A. OFICLE te4 ON FBEE INFQfiUATlON CARD WHAT S NEWS A review of the latest happenings in electronics. World^s smallest infrared antennas Scientists at the National In- stitute of Standards and Tech- nology (NIST) in Garthersburg, MD have produced antennas the size of a single grain of sand. The scientists believe they might have industrial importance and might also help ex- plain how insects communicate. The antenna development paves the way for unique infrared detec- tors that rely on antennas to "see" images of heat radiating from all warm objects such as people, ani- mals, and buildings. The micn3antenna is unlike con- ventional communications anten- nas for operating at the longer wavelengths that require larger an- tennas that might range in size from 1 meter in diameter (for radio and TV broadcast) to 100- meters (for deep-space communciations and radio astronomy). The NIST "micro- antenna*' is only 60 micrometers wide, about the diameter of human hair Yet it can effectively capture the extremely short wavelengths of f.. UNY INFRARED ANTENNA developed by NIST scientists is shown next to a human hair. infrared radiation. Wade of gold, the micnDantenna can pick up infrared wavelengths at one sixth the range of previous antennas. About half of the infrared energy that falls on the antenna is delivered to the detector at the device's cen- ter. Superconductive material was used in the development of those detectors which are so small that they cannot effectively capture in- frared radiation unless they are cou- pled to antennas. The goal is to build an array of the microantennas to provide an infrared image of ob- jects within its field of view. Scientists have long suspected that tiny structures on certain insec- ts were actually "organic infrared microantennas/" used by the insec- ts to 'see" in the dark. Energy storage breakthrough Quadri Electronics Corporation (Chandler, AZ) has been granted a patent on a new energy-storage de* vice, called "Hypercap." It provides far more storage than similar-sized capacitors and, when used in com* bination with CMOS RAM to pro- vide nonvolatile memory, over* comes many of the problems inherent in lithium and nickel*cad- mium batteries, Quadri plans to sell the product in an energy module that will mount directly on a CMOS RAW memory PC board to provide power for nonvolatile storage- Neither a batter/ nor a conven- tional capacitor, Hypercap has some properties of both. According to Quadn, the solid-electrolyte, radi- ation-hard device can be deep dis- charged and recharged tens of thousands of times. It contains no lithium or toxic chemicals and the company says it will not outgas. ex- plode, or ignite. The Hypercap oper- ates over a temperature range of -bS'C to -^t25'C and is said to provide about 100 trmes the energy storage density of a wet*siug tan- QUAORI ELECTRONICS researchers have developed a new technology for high'densjty, radiation-hardened ener- gy storage. talum capacitor Hypercap dis- charges at less than 3% per year. Promoting amateur radio A new educational pn^gram cre- ated by Kenwood U,S.A, Corpora- tion CLong Beach. CM is designed to encourage young people to learn more about amateur radio. More than 2000 amateur radio clubs in the United States are being invited^ in a special mailing, to join Kenwood in sponsoring a local junior or senior high school class, scout troop, or youth club in the Kenwood KIDS program," Each club that responds to the mailing will receive a package of educational materials. The pack- age includes ten copies of the ARRL publication Now You're Talk- ing and the companion instructors guide, as well as a certificate for the Kenwood HamWindows computer program. According Tom Wineiand, Vice President Communications and Test Equipment Division. "The heart of the program is education, but we have built-in incentives for both the kids and the co-sponsoring clubs. Every youngster who suc- ceeds in obtaining a license will re- ceive a S25 Kenwood gift certifi- cate. while the sponsoring club will receive ten $25 certificates for each successful class. The participating schools and clubs can also win complete HF stations, R-E WHAT YOUR TOOLS SAY ABOUT YOU. "Ultimate Professional" Heits the nc^Tcst hmtly member: the 60 MHz Ttk 224- Irs as rugged, reliabte ar>d casv lo use as the rest of the 220Scri€S-and exccnded bandwidth makes it the togiciJ choice for compunrr service professionals. "Rugged SuRvivALisr Teks 222PS Boftrr Scout'" offers the field-pro^'en per- fomiancc of the 222, pim its rated 600 VAC, 850 VDC and 6 kV peak surge. Perfect for circuit measurements requiring extra protection -and a few added guts. "Ace Troubleshooter" The Tek 222 is e\^ry*thing a service scope ought to be. Lighrft-eight. Rugged, hilly programrriablc. Floatiable to ±4(X) V, Tw channels, 10 MHz, Auto Setup and Auto Trigger make it easy finding ttouble-iiKt, /ww\ Tfektronix 222 'JSSS^ Theyrc just 4K: pounds. U.L. certified. And start at $2450. 220 Series handheld oscillracopes-all with Teks exclusive IsolatedChanner** architecture -are the service tools the professionals use. Theres one with you written all over it. To order, contact your Tek tepresentative or distributor Or just call Tek direct: 1-800-426-2200 Tektronix /l^st and Measuremenl CIRCLE 176 ON FREE INFORMATION CARD VIDEO NEWS Whats new in the fast-changing video industry. DAVID LACHEHBRIIGH • Widescreen TV age. Widescreen TV is here, with expen- sive sets ready to go. but very little specially formatted programming to show on them. JVC promises to be the first brand to offer sets on the American market — although only in token quantities — to be foitowed by Thomson Consumer Electronics, which wilf field larger numbers un- der its RCA and ProScan labels. Both brands wilJ offer these wide- screen (16:9 ratio) sets with direct- view tubes measuring 34 inches in viewable diagonal, the equivalent of a stretched-out 27'inch tube. At our deadline, prices for the United States hadn't been revealed, but similar widescreen sets on the Japanese and European markets were fetching the equivalent of $5,500 to $7,000 in list prices. Nei- ther Thomson nor JVC was talking about low prices, so it's a good guess that the tags here will be in line with those other countries. Thomson, which is making wide- screen tubes at its plant in Italy has indicated that its imported wide- screen tubes in the United States currently cost five to six times as much as a 4:3 ratio counterpart. • Widescreen VCR's. JVC has developed a VCR which can accom- modate bofh widescreen and stan- dard-ratio pictures, telling the TV set what type of picture is on the tape. The widescreen pictures are compressed horizontally, as com- pared with letterbox pictures, whEch leave a blank horizontal band at the top and bottom of standard-ratio screens. The recorders are in the Super VHS format, and are already on sale in Europe and Japan. Thom- son will offer widescreen camcor- ders in VHS, VHS-C, and 8mm formats, but they will just have hori- zontal strips masked off at the top and bottom of the picture to provide a letterbox format (they'll also be able to record a standard picture). At first, widescreen TV s will de- pend on letterbox material for pre- recorded programming (although they can also display standard-for- mat material), and Thomson says some 400 movies are available in that format on Laserdisc. Because letterbox movies occupy only a portion of the picture vertically, ver- tical resolution is reduced. The Thomson widescreen TV's will use the "double-scan," or IDTV ap- proach, doubling the number of hori- zontal lines, and also adding motion compensation, while JVC's set will have standard interlace and the nor- mal 525 lines. • HDTV worries. Although the United States is only now involved in testing proposed high-definition TV systems, all of the systems which are serious contenders are digital. As a result, the US has moved from last place to first place in the HDTV sweepstakes. Even be- fore any digital system has been proven viable, America's digital ap- proach has struck fear into the hearts of Europe and Japan. The European community had de- veloped a gradual approach to HDTV; the D2-MAC system was supposed to evolve into something called HD-MAC m direct-to-home satellite broadcasts. They decided, however, to make the transition op- tional so the new system wilf never be effected because of the reluc- tance of satellite broadcasters to convert to a system that nobody is equipped to receive. In Japan there is similar discon- tent, although the Japanese Hi-Vi- sion system is now being broadcast by satellite by the Japan Broadcast- ing Company CNHK). The analog system, however, is based on 20- year-old technology and requires extremely complex receivers. Re- cently the Hi-Vision partisans hailed a major breakthrough, and receiver prices came down from the equiv- alent of $70,000 to $30,000! Increasingly Japanese manufac- turers and broadcasters are begin- ning to realize that Hi-Vision is a system whose day has come and gone. How ironic it would be to find the United States emerge as the leader in this technology because it had to find a fresh approach, • Rethinking HDTV. Increasingly, we are hearing rumbles that maybe HDTV — digital or ana- log — isn't what it's cracked up to be. In Japan, enthusiasm is growing over widescreen 16:9 TV without improved resolution, which many observers are saying goes more than halfway to HDTV in consumers eyes. Even at Sony, which has been among the staunchest advocates of Hi-Vision, Deputy President Ken Iwaki recently called its gamble on HDTV a "miscalculation/' In the US, some doubts are aris- ing about the value of HDTV. The MIT Media Lab. in the past, has noted that the quality difference be- tween a broadcast station s NTSC monitor and the received TV signal in the home is greater than the dif- ference between NTSC and HDTV, Consumer tests show that the greatest perceived value of the HDTV picture is the wide screen. • Ghostbusting. One of televi- sions major drawbacks, ever since the first broadcasts, has been ghosting. The average consumer in an area plagued by ghosts might find elimination of ghosts in a con- ventional picture a greater achieve- ment than HDTV. The National Association of Broadcasters has tested five different ghost-cancella- tion systems, using three Wash- ington area TV stations, and should announce the results soon. All of the systems require the transmis- sion of an invisible pilot signal by the TV station, and special receivers to make use of that signal. After more than 40 years of TV, it now appears that the system s biggest technical problem is about to be licked! R-E DONT GAMBLE when you want the best - 2 1 Reasons To Buy OPTOELECTRONICS' MODEL 3000 All RANGE- 10H2 1O3GH2. Hi-Speed ASIC (Application Specific Integrated Circuit) State-Of-TTie-An 256 Times Faster than other hand held counters. 10 Digit LCD, Readability even in Bright Sunlight 6 Functions - Frequency, Period, Ratio, Time Interval, Average and Prescale, RF Signal Strength Bargraph - 16 Segment, Zero & Full Scale Adjust. Excellent for locating Hidden Transmitters, Four extremely Fast Gate Times .01 , . 1 , 1 , 10 sec. Dual High Impedance Amplifiers. Maximized Sensitivity Hold Switch * Locks in measufements FAST. + 1 PPM Accuracy Direct Count - IHz resolution to 220MHz Sensitivity <1mv 10MHz - 200MHz. <5nrTv * 2GHz, Single Shoi Time Interval 100ns, .Ins averaged. Push-button Input, Gate & Function setectjon. Extruded Aluminum Enclosure. NiCad & Charger Included. t_ow Battery Indicator. 1 Year Parts & Labor Warranty 30 day Money Back Guarantee. OPTOELECTRONICS backs this with our 18 Years ol Dependability & Service. this and more for the Low Price • $375, OPTIONS: TCXO SO 1 2p^TCX0 »„,».....$tOO. BLB30 lig^^ & two m«N3ia sigrtaf \m0 Mmat ..$ 75. CC30 Ca«y Case .......S 15* TA100S Te*escGp«nQWhio Antema ......S 12 Also Available at Special Package Price; For A Limiied Time Only Model 3000, Backlight/Beeper, Carry Case & TA-IOOs Whip Antenna All this for only $449, Factory Direct Order Line 1-800-327-5912 {305)771-2050 • FAX{305) • 2052 5821 NE 14th Ave. * Ft. Lauderdale, PL 33334 5% Ship'StoKiling (Max. $10) U.S. & Canada. 15% oulside continental U.S. Visa & Master Card A«:ep!ed, CIRCLE 190 ON FFtEE INFORMATION CARD YOU CANT LOSE! If Ybu're Serious AbcMit a Fkituie in Electronics, Ensuie that Future with the Best Educational Tk'aining Available. SEND FOR YOUR CIE HOME STUDY COURSE CATALOG AND RECEIVE A fRBB 24 PAGE GE ELECTRONS SYMBOL HANDBOOK* Jntludcs hundreds of the moil frecfuenlly used eJectronfc symbols. Pi/ blushed by CIE excJusivoly for our students and ^fumnL Yours free when you request a 0£ Course Catalog. L -f you want to leam about electron- tcs, and cam a good income with that knowledge then CIE is your best educational value, CTE s reputation a$ the world leader in home study electronics is based solely on the success of our graduates. And we've eBTne<^ that reputation with an unconditional commitment to provide our students with the very best eJectronj"c5 training. Ju5t ask any of the 15Q,000'prus graduates of * the CJcvcland fnstitute of Efectronics who are working in high-paying positrons with aerospace, computer, medical automotive and communis cation firms throughout the world. They 71 tell you success didn't come easy. ..but, it did come.. ..thanks to CI E. And today, a career in elec- trontcs offers more opportunities and greater rewards than ever before. CIE 5 COMMfTTED TO BEfNG THE BEST.„.fN ONE AI?EA„„ELECTRONfCS. OE isn t another be-everything-to- everybody schoot. We teach only one subject and we believe we re the best at what we do. Also, CIE is accredited by the National Home Study CouncM. And with more than a 1 ,000 gradu- ates each year, we're the largest home study school specializing exclusively in electronics. CIE has been training career-minded students Irke yourself for nearly 60 years and we're the best at our subject ELECTRONICS ... BECAUSE ITS THE ONLY SUBJECT WE TEACHI CJE PROVIDES YOU WITH A LEARNING METHOD SO GOOD, ITS PATENTED. CIH s Auto-programmed lessons are a proven learning method for building valuable electronics career skills. Each lesson is designed to take you step-by- step and princrpJe-by-principle. And while ail CIE lessons are designed for independent study, CIE's instructors are personally availsb^c to assist you with just a toll- free call. The result is praciical training... the kind of experi- ence you can put to work in today s marketplace. LEARN BY DOJNG„.WrTH STATE-OF- THE-ART FACIUTIES AND EQUIPMENT, Jn 1969, CIE pioneered the first Electron res Labora- tory course and in 19S4, the first Mirco processor Laboratory course. Today, no other home study schooJ can match CIE s state-of-the-art equip* ment and training. And alJ your laboratory equipment, books, and lessons are included in your tuition. It's all yours to use while you study at home and for on -the -job after graduation. PERSONAUZED TRAfNING„.TO MATCH YOUR BACKGROUND. While some of our students have a working knowledge of electronics others arc just starting out. That's why weVe developed twelve career courses and an A.A.S. Degree program to choose from. So, even if your not sure which electronics career is best for you, CIE can get you started with WHY CHOOSE CIE FOR YOUR TRA1NING7 ■ 150.000 successful graduates from every country around the world. ■ Only CIE rewards you for fast study, CIE offers an Associate Degree program based on actual study time used. The faster you complete your degree the less your overall tuition. ■ States f-the^rt laboratory equipment is yours to keep and it comes assembled, ready for hands-on experiments. ■ Approved for educational benefits under the G J. Sill for veterans and other eligible persons, ■ Upon graduation, CIE offers free preparation to pass the Certified EJectronrcs Technician Exams. core lessons applicable to all areas of electronics. And every CJE course you take earns you credit towards comple- tion of your Associate in Applied Science Degree, So you can work toward your degree Jn stages or as fast as you wish. In fact, CIE is the only school that actually rewards yoo for fast study^ which can save you thousands of dollars. SEND TODAY FOR YOUR CIE COURSE CATALOG AND WE IJ_ SEND YOU A FREE 24 PAGE CJE ELECTRONICS SYMBOL HANDBOOKf □ want to get started. Send me my CIE school catalog includ- ing details about the Associate Degree Program* [For your convenience, CIE will have a representative contact you - there is no obligation.! Name: AE37 Address:. Ciiy:. State; Zip: .Age: . P none No. i . Check tx>x for G.f. BiJlletin Benefits LJ Veiefan Z -Actfve Duty Ikm. CLEVELAND INSTITUTE OF ELECTRONrCS 1776 Eas! 17lh Sirool CFeveland, Ohio 44114 (2161 781-9400 A schoot of Ihous^n^. A ciass of ofK? ASK R E Write to Ask R-E, Radio-Electronics, 500-B Bi-County Blvd. Farmingdale, NY 11735 1 I § 2 6 I n SKIP THE ZERO rm building some electronic dice for my children who are vi- sually impaired. For that reason I'm using a large seven*segment display and Tve run across a problem 1 can't seem to solve. I'm using a 555 to drive a 7490 decade counter which rs con- nected to a d36B decoder driver latch. Two AND gates reset the circuit after the six count and the problem is that the count in- cludes a zero. The blanking in- put on the 9368 wilt just turn off the LED's so my choices seem to be limited to having either a zero or a blank in the display — neither of which you want with dice. Is there some trick I can use to have the 7490 skip the zero count? — J. Mullane, Dunn Loring, VA When digital elecErDnics filtered down to the hobby market some twenty years or so ago. electmnic dice were among the most common projects you could find. Of course, they were all made with discreet LED's instead of seven-segment displays so your particular problem never really presented itself. First of all, there's no way — short of microsurgery — to alter the count of the 7490. That isn't to say that you can't solve the problem but the idea is to do it with a minimum of brain damage. Given that criterion, you can throw out all the schemes (most of which you've undoubtedly thought of) that use the reset pulse to force feed two counts to the clock or the 7490. It s possible to do that but the gating problems , while solvable, are a pain in the neck and always lead to the addition of lots of silicon to what shouU neally be a simple, straightforward circuit. Although there are several dif- ferent appnDaches that can be taken to come up with a solution to your problem, if I were building a circuit tike yours, 1 would rethink the entire circuit. The most direct way to eliminate the zero count altogether is to rec- ognize that the problem is being caused by the 9368. not the 7490 as you indicated in your letter If you think about the circuit for a minute, you'll nealize that you're resetting the 7490 after it s gone through seven counts— zero through six. All the solutions that try to gate in two counts at reset still let the 7490 go through seven counts, not six (which is really what you want for dice). Keeping that «n mind, it s clear that you want the 7490 to be reset after six counts, not seven. The problem you're left with is that the 9368 causes the display to show the numbers zero through five when the 7490 puts out its first six counts. What you want to happen is to force the 9368 to put out a one when it has a zero at its inputs, a two when it sees a one. a three when it sees a two, and so on, Unfor- tunately- making it do that is what the engineering journals refer to as a "nnajor problem." The way around the problem is to get nd of the 9368 altogether and hnd a decoder driver latch that does it automatically Til save you a lot of research time and tell you that there's no such animal around. The way to do it is to use an EPROM and make one of your own. It's a simple thing to do and the tmth table for the EPROM you are going to need is shown in Table 1 . There's a lot of wasted space in the EPROM since you're only using the first six out of a total of 2048 storage locations (assuming you use a 27t6). But EPROM s are cheap and as long as th^ do the job. who cares how efficiently they're being used'? Burning an EPROM used to be an exotic activity but EPROM burners (particularly those that can do 27 1 6's) arB cheap and available from just about every supplier in the worid. If you don't have one jroucan probably find someone locally who does but. if you're interested in TABLE 1— EPROM CHARACTER GENERATOR CHART Input Programmed Output Data LEO^ EPROM 0 D D D D D D D Hex Segment Address 7 6 5 1 4 3 2 1 0 Data Byte Display Common- -Cathode Di Splay 000 0 0 0 0 0 1 1 0 06 1 001 0 0 1 t 0 1 1 5B 2 002 0 0 0 t 1 1 1 4F 3 003 0 1 0 0 1 1 0 66 4 004 0 1 0 1 1 0 1 6D 5 005 0 1 1 1 1 0 1 7D 6 Common — Anode Display 400 1 1 1 1 0 0 1 F9 1 401 0 1 0 0 t 0 0 A4 2 402 0 1 1 0 0 0 0 BO 3 403 0 0 1 1 0 0 1 99 4 404 0 0 1 0 0 1 0 92 5 405 a 0 D 0 0 1 0 82 6 Note 1, Be sure to conned all unused EPROM address lines lo either ground or power Note 2. The EPROM output pins are assigned as follows: DO - A Segment DI - 8 Segment D2 - C Segment D3 - 0 Segment D4 - E Segment D5 - F Segment D6 " G Segment 07 - Decimal Point FROM N T E THE FULL SPECTRUM OF Rda^andA : NEXT WAVH OUR SUCCESS! NT£ is building on a decode of enorfnoLrs success in universol semi- conductors, resistors, ond copadfofs in o major way! We're introducing a full line of reloys and acces- sories that odd to the value of using NTE as your #1 second source! MORI WAYS FOR YOU TO SAVE TIME AND MONEY! We've added 270 relays, I/O modules, sockets and Gccessories to our inven- tory of over 6,000 univer sal devices that replace over 245,500 onginal numbers! PRICE, PERFORMANCE AND FAST AVAILABILITY! All orebockedbyNTE^s reputfltion for offordobil- ity, unsurpossed quolity and immedioFe parts ovailobility! Moil tbe coupon today to get your FREE copy of NTE's new Relays and Accessories catalog today! 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OnJy NRI, tbe leader in career-building at-home elecironics training for more than 75 >'ears, gives you that kind of pracUcaK real-world computer servicing experience. Indeed, no other training— in school, on the job, anytrbere — shows you how lo troubleshoot and service compuieni like NRI. Get inside the West Coast 386sx computer system... and experience all the power and speed of today's computer technology! With NRI s exciusivc himds-on training, you actually build and keep the powerful new West Coast 386sx/2() MHz mini tower computer s^siem. 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If the coupon is missing, write to NRI School of lUectronics, McGraw-Hill Continuing Education Center, 4401 Connecticut Avenue, NW, Washington, DC 20008. guJcktech and K^.<^E„H. zrr inuMcrrd indcncuio iif lltra-K. Inc. Wnt iloast iA i mcrohcr uf ihr Syntax Group. compatible computers. You'll use your IJltra-X QuickTech diagnostic softw arc to test the s) stem RAM and such peripheral adapters as parallel printer pons, serial communications ports, video aUaptcfh, and fl(»ppy and hard disk drives. You'll go on to use yo ur R. A. C.I*. R . d i agnos ticca rd , also from IJItra-X, to identify individual defective RAM chips, locate interfacing problems, and pinpoint defective support chips. This ingenious diagnostic package is just one more way School of Electronics McGoW'lliU ContintiinK Cdtcailon Center i 101 Oinnctticut Avcriiic. SW UashLngton. 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That's why iaboralorv courses — where real circuits using real components are assembled by students — are required for gradua- tion. !n our experience, however most laboratory classes are too few and far between to reinforce many important lessons. Worse yet. most lab courses don't follow the same syllabus as the theory courses as* signed in a given year Students can supplement their coursework with independent lab experiments, but that requires access to test equip- ment and components. We've found a product that will allow students to supplement their coursework without buying a full test lab. Prviolah Release 3.0 from Global Specialties (70 Fulton Ter- race, New Haven, CT 06512,), Protolab software turns your PC into a computer-simulated elec- tronics laboratory. You can build cir- cuits on-screen, and use simulated test equipment to examine their be- havior. Its not only students who will benefit from Protolab. Many schools could use the software . i part of their lab courses— at quite a savings over purchasing new equip- ment. The basic Praiofab program lets you build circuits made up of re- sistors, capacitors, inductors, com- plex impedances, and AC and DC voltage and current sources. A cir- cuit is built on the Protolab breadboard with the help of pull- down menus; a mouse is used to place components. A circuit can consist of as many as 40 compo- nents. Once the circuit is built, you "turn the power on" to start the circuit calculations. Once the computer has finished the calculations, you can use the test equipment to ex- amine the circuit s function. A volt- meter, ammeter, ohmmeter, watt meter, signal generator, and os- cilloscope are available. Of course, once you get the basics of DC and AC circuit theory, you're going to wish for more ca- pability—such as the ability to work with active components. IJnIike the original version of Protolab, Release 3.0 does support active compo- nents and other advanced topics — albeit with some limitations. We fooked at three modules that are available fnom Global Specialties The Protoware Diode Module covers full -wave and half-wave rec- tifiers. Only those two circuits are available. Although you can change component and voltage values in the two diode circuits* you cannot alter the circuit configuration or de- sign your own. The Transistor Amplifier Module contains three circuit configura- tions, a common-base, common- collector, and common-emitter am- plifier. The common-emitter ampli- fier also allows you to study the circuit either taking only the DC bras into account or the entire AC and DC circuit. The Protoware Organ Module presents a 4-note eiectnDnic organ based on the LM3909 LED flasher You can "play" the organ by using the mouse to click on one of the four switches. The organ module also continued on page 7t One of these three sets con be yours for only $4.95 when you join the Electronics Book Club"'' Your soune for • . • *:* Troubleshooting & Repairing Keep your VCRs. radios, stereos, and personal computers in pristine operating condition witti ttiis collection of books. Detailed illustrations and sfep-by-step instructions will show you hiow to get your equipment up and running, and save you a fortune in repair bids, #586125-9 Bcnic Reference Take ftie mystery out of basic electronics and electronic circuitry with this set of compre- hensive electronics reference books. You'll soon be reading circuit diagrams as easily as the morning paper and applying your knowledge of electronics to hundreds of practical projects at home or on the job. #586126-7 Project Building Electronics hobbyists toke nofef This workbench wonderland of electronics projects will bring you hours of enjoyment and tremendous savings. Before you know it, you'll be assembling robots, personal computers, and a multitude of fun and useful electronics gadgets. #586127-5 Membership Benefits • Big Savings, in addition to this introductory offer, you keep saving substantially with members' phces of up to 50% off ttie publishers* prices. • Bonus Books, Starting immediately* you will be efigible for our Bonus Book Plan, with savings of up to 80% off publishers' prices. • Ctub News BuHetms. 15 times per year you will receive the Book Club News, describing all the current selections — mains, alternate, extras — plus bonus otters and special sales, with scores of titles to choose from. * Automatic Order. If you want the Main Selection, do nothing and it will be sent to you automatical- ly. l( you prefer another selecliont or no book at alt, simp- ly 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 thereafier, ■ ironctad No^Risk Guarantee. If not satisfied with your books, return them with i ft TO days without obligation! • Exceptional QuaKty. All books are quality publishers' editions especially selected by our Editorial Board. {Puttis**efs' Prc« Shownj 1992 ELBJrRONlCS BOOK CtUB, Blu« HkJff* SummiU PA 17294.^10 i/H Ej.ECTfiaWICsBQQhCj.l)B^ Jf9 Blu© Ridge Summd, PA 17294-0810 [I] YES? Pfease accept my membership in ihe Electronics ScK* Club and send ihe 3 volume set iridicaled below, bilting me If not satisfied. I may r&tum the bocks, wfthin ten day^ witfiotJt obTigatkJn and have my membership canceiled. I agree to purcl^ase at least 3 books at regular Club prices during 1 ha next 12 rnonths and may resign any lime Ihereaftef. A Ehipping/hanOling charge and sales tax will tye added to ail orders^ □ Troubleshooting and Repairing Set #586125^9 □ Basic Reference Set ^^566126-7 □ Project Building Set #586127-5 hfame ^ Address City State . -Zip. . Phor*e , Sig nature vten$ fa emw nwnbM only FeivQn 4«cite«nsi rwotf^ tpK^wt ordaring ^istructiOit Cvwu /ni^ ftftii m U S evTvncY Tfra v4er ibAfKi tD KCApufpc* try trw EtietforKi Soofc RPIE49Z NEW PRODUCTS Use the Free Information Card for more details on these products. lij g 26 CLAMP-ON CURRENT METERS. Measuring cur- rent is becoming more complicated. Personal computers, adjustable- speed drives, and other equipment that draws cur rent in short pulses Cnon* linear loads) can draw high- peak currents. That causes harmonics to appear in the current, creating such problems as overheated transformers and neutral conductors, and unex- plained tripping of circuit breakers. Therefore, for accurate measurements of currents containing har- monics, a true-RMS meter is Inquired. The 30 Series Current Masters clamp-on meters from Fluke measure true- RMS current up to 700 amps at fnequencies to 10 kHz. helping technicians track down the hot spots before they become major problems, Their rugged, angular design makes them compact enough to maneuver easily in crowded breaker boxes » yet large enough to sur- round large-diameter con- ductors. Model 31 and model 33 both offer a host of features for trou- bleshooting current prob- CIRCLE 16 ON FREE INFORMATION CARD lems. These include man- ual and autorange modes, display hold, sleep mode (for battery conservation), and a powerup self test. Each unit comes with a pro- tective holster that can be attached to a work belt. The Fluke 33 also in* eludes features that allow the technician to perform more m-depth current tests and to record data For as long as 24 hours. The mm/ max feature records the maximum and minimum values and calculates the average for both RMS cur- rent and frequency. The smoothing feature calcu- lates and displays a three- second running average for both frequency and cur- rent- A crest measurement reads or detects the half- cycle peak, and it can be used to determine the crest factor, showing if the waveform is distorted or sinusoidal Fluke models 3t and 33 cost $179 and $249, re- spectively. — Jtihn Fluke Mfg. Co<, Inc. P.O Box 9090. Everett. WA 98206: Phone: 800-44-FLUKE. LOW-NOISE CERAMIC CA- PACITDBS. According to Rohm Corporation, its MCH Series' NPO/COC '>^" chip capacitors have the industry's best equiv- alent senes resistance CESR) characteristics in their price class, and they have been found to per- form comparably with much more expensive high- RF/microwave chips. Made with pure palladium electrodes and fired at higher temperatures than competing chips, they de* liver better ESR ratings. The MCH Series ceramic capacitors are available in 0805 and 1206 sizes, with a capacitance range of 0.5 to 2700 pF for NPO di- electrics, and 680 pF to 0,22 liF for X7R di- electrics. The popular toler- ances of 5% For NPO and + 10% for X7R are both available. Series operating temperatures can range from - 55X to -f 25X. The chips are designed for both wave and IR reflow soldering methods. De- signed for automatic place- ment, they are available in Bmm tape-and-reel format. Both 7-inch (4.000 pieces) and 13-inch (16.000 pieces) reels are available. QRCIE 17 ON FRff INFORMATfON CARD Prices for the MCH Se- nes ceramic capacitors range from $15,80 to $45:t0 per 1000 pieces.— Rohm Corporation. 3034 Owen Drive, Antioch, TN 37013; Phone: 615-641-2020. ext. 117: F^x: 615-641-2022. LAB INTERFACE Kit De^ signed to meet the needs of engineers and techno cians. Probe Masters Lab Interface Kit contains a CIRCLE 18 ON FREE tNFORMATION CARD combination of the most often used adapters < termi- nations, and attenuators, as well as two precision BNC RG5S/U cables that can be used for calibratron lab standards. The adapt- ers provide peak perfor- mance and are designed to minimize reflective losses. The kit comes in a moisture-resistant, high- impact case that protects each adapter. The Lab Interface Kit costs S199.— Probe Master Im., 4898 Ronson Court, San Diego, CA 92111-1807; Phone: 800-772-1519. BACKPACK TOOL ORGA- NIZER. Particularly helpful in situations that require the engineer or technician to keep two hands ffBe for carrying heavy equipment or gripping handrails, the 7bo/pa/f from F^ktek allows him to carry more than 100 tools, charts, and meters on his back. The pack makes it easy to carry afl the right tools to the work and to find them quickly. Three zippered compart- ments contain six fold-out tool panels with more than 100 pockets for holding tools securely m place, and a targe pocket for maps and schematics. In addi- tion, two outer pockets provide quick access to fre- quently used toots or sup- plies. The ToolpaK which is made from durabte punc- ture and abrasion- resistant nylon, has heavily padded straps for comfortable wear and attache-style handles for hanging or car- rying the pack whife it s un- zipped. CIRCLE 1*1 ON FREE INFORMATION CARD The Tooipak tool orga- nizer costs 399.97 (plus $4 shipping) —Paktek Inc.. 7307 82nd St. Ct. SWTac- oma. WA 98498: Phone: 1-800-258-8458: Fax: 206^851-2365. PORTABLE 100-MHr OS- CILLOSCOPE. Measuring fust 3/4 inches high by 916 inches wide by 13^4 inches deep, and weighing just nine pounds. Leader's model 326 100 -MHz os- cilloscope fits easily into an attache case for portable use by field service engi- neers and technicians. The two-channeL dual-time- base scope has a 12-kV CRT with an ilfuminated graticule. An alternate sweep with a calibrated- delay time base permits si- multaneous display of the tJRCLE m ON FREE INFORNUTION CARD observed waveforms and the time-expanded sec- tions. Two asynchronous signals are displayed at the same time by the 326, thanks to an alternate trig- gering mode and complete triggering facilities. The model 326 os- cilloscope has a suggested list price of S2795. — Lead- er inslruinents Corporalion. 380 Oser Avenue. Haup- pauge, NY 11788; Phone: 1-800-645-5104 (in NY. 5l6^23t-6900X DUAL SLEEP-MODE OP AMR With two separate modes of operation. Motorola's MC 33102 dual Sleep- Made op amp has very low standby power operation. In the sleep-mode state, it operates with a very low current drain. Each ampli- fier automatically changes to the awake-mode state when an input signal is ap- plied to the amplifier caus- ing it to sink or source sufficient load current. The CIRCLE 21 ON FREE INEORMATJON CARD op amp uses industry-stan* dard pin-outs and has inde- pendent sleep-mode ca- pability with no extra pins or external components re- quired. Key applications am those that require impnDved energy efficiency For ex- ample, the amplifier can operate in a mode that con- sumes just enough power to detect incoming signals and then shift to a higher performance mode upon demand. That nnakes it ide- al for use in cordless phones, portable comput- ers, tape recorders, baby monitors, sensors, auto- mobiles, hand'held equip- ment, cordless appliances^ and battery-operated test equipment. The MC33102 changes from sleep mode to awake mode in 4.0 microseconds when the output current exceeds 160 microamps, and automatically rBtums to the sleep mode when {he output current drops below the threshold. It can be used as a fully functional micropower amplifier in the low-current sleep-mode state. Crossover distortion is as low as 12.0 Hz in the awake mode. ESD clamps protect the inputs, incnsas- ing stability without affect* ing amplifier performance. The device is available for commercial applications in both an 8- pin plastic DIP (MC33102P> and an 8-prn plastic SO-8 surface- mount package (MC33W2DI In quantities of 10.000. the MC33102 costs $1.60.— Motorola Inc. Bi- polar Analog IC Division Marketing, EL340. 2100 East Elliot Road. Tempo, AZ 85284; Phone: 602^897-3615; Fax: 602-897-4193. AUDIO MEMORY/VOICE KEYER. If you want to trans- mit two letters over and over, or repeat a contest CO thousands of times in a two-day period, the Ventriloquist voice keyer and audio memory device can help. Based on the ISD1020 nonvolatile ana- log memory chip, j-COM's device stores sampled ana- log speech signals for up to ten years, even if the power is shut off. The Ventriloquist can hold four variable length messages for a total of 20 seconds of high-fidelity au* dio storage. Each message can be played at any time by pressing one of the four message keys. A built-in microphone for recording and a speaker for playback are included, A PIT keying circuit is provided to oper- ate the transmitter auto- malically when a message is played. The Ventriloquist can be set up to endlessly recond your DX QSO's with an endless-loop necord and playback feature- The unit interfaces with most mod- em transceivers, ft also has ^ a built-in computer inter- 'j^ face that can be connected S, difBClly to the printer port ^ of any PC-compatible com- g puter and it is compatible g with the popular CT con- i- test'iogging program. ^ Although the Ventrilo- quist was designed to be used as a voice keyer it has 27 many other uses. For lan- guage training, you can rec- ord the instructor's voice in one message and try to match It in another A sam- ple program code in BASIC and C programs is provided to illustrate how easily you can add speech output to any computer application. The remote interface can be used to trigger speech output from alarm sys- tems, motion detectors, or other sensors. Connected to your doorbell it can an- nounce "Someone is at the door!" The voice keyer CIRCLE 22 ON FREE INFORMATION CARD can be used as an audio notebook when driving or when it's too dark to see what you're writing. The Ventriioquist voice keyer/audio memory de- vice is available as an as- sembled and tested board for $124.95. or packaged in a high-impact ABS enclosure For $149.95. — i'COM, RO. Box 194. Ben Lomand. CA 95005: Phone: 408-335-9120; Fax: 408^335-9121. SOLID-STATE REUY. Offer- ing high current in a small package, the CSAC-01 Mfni'SP solid-state re [ay from Gordos permits a iarge number of output cir- cuits to be placed on a small amount of PC board space. The relay is housed in a single in-line package that measures 0.7x TOxOJS inches. It offers a 12- to 240-VAC output rated at 2 amps RMS at a 25^C annbient temperature. The solid- state relay features zero- voltage turn -on. 3750 VAC optical isolation, and 10- mA DC input sensitivity UL. CSA. and VDE ap^ CIRCLE 23 ON FREE INFORMATtON CARD provals are pending. The GSAC-01 mini solid- state relay costs $3.65 each in quantities of 1000, — Gordos, 1000 North Second Street. RO. Box 824, Rogers. AR 72757; Phone: 800-726-5000 or 501-636-5000; Fax: 501-636^2305. FET DYNALOAD. Transistor Devices Inc. (TDD Dyna- loads are power-sinking de- vices used to simulate a variety of complex elec- trical loading conditions in CIRCLE 24 ON FREE INFORMATION CARD the design and testing of power-conversion sys- tems. According to TDI, the DLF-4000, with its 4000- watt power dissipation rat- ing, is the most powerful stand-alone electronic load on the market. The instru- ment can be used for easy creation of complicated load profiles that allow power-supply engineers to verify the integrity and sta- bility of their designs. It can also be used in production environments for system burn-in and for incoming in- spection and test of power supplies, batteries, and other power sources. Its low compliance voltage means that the DLF'4000 can be used for special ap- plications including things like testing 1.5-volt battery cells or other sinnilar ap- plications. The instrument uses FET's to achieve an ultra- fast response time of less than 15 naicroseconds and a low compliance voltage of under 0.15 volts. With an operating range of 0-400 volts, and load currents From 0 to 600 amps, the DLF-4000 can dissipate up to 400O watts. Multiple in- struments can be paral- leled to increase current ratings and total wattage dissipation for the testing of larger power sources if necessary, The DLF~4000 costs about $8000 —Transistor Devices Inc., 274 Saiem Street, Randolph. NJ 07869-1697: Phone: 201-361-6622; Fax: 201-361^7665, SURFACE'MOUNT CRVS- TALS AND OSCILLATORS. Ralton s family of four crys- tals and oscillators for sur- face mounting offer output frequencies ranging from 624 kHz to 300 MHz, Three of the four are funda- mental quartz resonators, two of which are produced from ultra-small 'AT strip" crystals. Those two are the newly packaged HC'49 and TT-SMD products are available for use over the 3 MHz to 50 MHz band. The HC-49 is in a metal SMT can; the TT-SMD is in a plastic SMT package. The third quartz resonator, the HC-45, is available with any frequency rating from 3.579545 MHz (for TV color-burst frequency) to 300 MHz (for high-speed logic). The HC-45's have a unique package design with a special clip that al- lows them to very easily be mounted and soldered flat on a surface-mount circuit board. The C0^99/00 is a com- plete, integrated SMT clock-oscillator circuit with an internal AT-cut" crystal. The clock oscillator circuit operates from 625 kHz to 24 MHz. is mounted in a 28-ptn plastic leaded-chip carrier fPLCC), and pro- ORCIE 25 ON FREE INFORMATION CARD vides a square-wave output with a TTL fanout of 10, or 50 pF of high-speed CMOS loading. In lots of 1000, the HC-49 costs 70 cents each, the TT-SMD costs 90 cents each, the HC-45 costs between 75 and 95 cents (depending on fre- quency and tolerance re* quirements). and the CO-99100 costs $2.50 each.— Ralton Electronics Corporation. 2315 NW 107th Avenue, Miami, FL 33182: Phone: 305-593-6033; Fax: 305^594-3973. R-E NEW LIT Use The Free Information Card for fast response. NATIONAL PARTS DIVISION CATALOG: from Tandy Elec- tronics, National Parts Divi- sion, 90Q East Northside Drive, Fort Worth, TX 76102; Phone: 800-322-3690; S7.00. Tandy's newest 232- page catalog of efectronic and eleclro/meclianical parts now contains listrngs of products from 29 well il€ms and check opfl ration in all lypea of digimi circuits. LEDs and "beep" tones reveal logic slates instantly Incltides own* er's booklet wiLh valuable iroublest^oot- ir>g bps #22*303. 16.95 BtisinttS9" tlLftsted AC cords witti GEE- lype oorinoctof lor many PCs. printers, moni- tors, copiers and test instruments. (1) e-Fl. Cord Wilh Rtghl- Angle Connector. (2) i2*Ft, cee Cord. *27a-l26l.5,99 (3) e-Fl, GEE Esrtenskm. *278'T259. 4.99 Special-Order Hotline The Fladio Shack near you stocks over 1000 electronic components— and anoiJiet 15,000 items are available fasl from our special^order ware- house, f^ake Radio Shack your corn- ploto source for liriear and digital ICs. iransi&tors and diodes, vacuum tubes. crysiaEs. phono Cartridges and styli. selected computer accessor ces and SAMS' service martuals There's no postage to pay because we send your order lo the Radio Shack near you Delivery time lor most items IS about s. we^k Corrn? m (or detaHs Build a Soldering Iron! (1) '^Cool-Qrtp" Handtc. UL hsced '*64'20e0 6.49 (2J 23>Watt Heating Element, UL iisied (Inierchangeable 33W and 45W eiemenls also in siOCk,) •64.2081 SM (3) Light-Duty Tips for Above. Set o( iwo. ^^64-2089 4,99 (4) Vacuum Desoldering Took m-2t20 (5) Mini Forceps. Insulated grips. #64-1910 1,79 {6) Lead-Free Solder. 96% tin. 4% silver formula. 0-032" si£e. 0.25 oz. #64-025 ..1.99 (7> High-Tech Solder. 63/37%. 0 050' stze. 1.5 oz. *64^0lS 2.49 (S) One -LJ>, Electronic Solder. 0.062' size. =64-008 B-tS Halogen Bulbs. Long- life, bnghter- than-origrnal rep lace men is tor your flash- light or lantern, HPRSO. 6V for 4-celi flashlighi or 6V lantern. #272-1189,3,95 HPR52. 3V for 2-ceii nashiiQhi or 3V lantern. #272-1190. 3.95 3' Bnishless i2VDCFan, Sest choice for cooling mobile equipment or , hum-sensitive ^ Circuits 1.0W no!se tevel— 34dB max. 27 CFM airllow. ^273-243, 14.95 High-Speed t2VDC Motor. Up to 15.200 RPM at no load. Ideal lor sci- ence projects and foiwtics. About 2' tong (inciudtng shaft J by I" diameiet #273-255. 2.99 12VDC Mag- neltc Buzzer, Nicef tone than pie^OS. *273'026, 2,19 "Ding-Dong*" Chime, IC and mini -speaker entry olerier 8I0 1S VDC. ^'273-071, a,99 Lighted AC Switch. Panel' mouniable sw4ch w!ih heavy-duty lO-amp ratir>g. 125VAC use only Push-on, push ofl action. But ion lights when on. #275-671. 3.99 Baliery Guide. Save money by choosing the fight baiteryl Data on our top-rated ENERCELL' brand plus a weallh ol basic battery info. 230+ pages, #62-1304, 5,95 Set of 100 Ceramic Disc Capacitors. Popular values at a bargain price. Ratings up to 1000 WVDC. (Big se- lection of resis- tor assoriments in stock, tool) #272-QDL Set 1.9B o> i LCD Mullimeter With Automatic ShuloJf. We've never seen such quality and features in a Ui-iisiod meter pricad so low! Full autorang* ing wilh manual override, data- hold, analog bar graph to spot trends, 10 amp and 200 microamp ranges 7^^- high. #22-167 69.95 6-Ft. BNC'tO- BNC Patch Cable. For tesL RF tK)okups. *278'964. 5.99 3-Fl, Cellular Phone Exien* sion. Male TNC to Female TNC. p27S-g76. 4.99 Building Power Supplies. Cov' ers linear and switching lypos and inctudes full construction plans for five supplies, 96 pages. #276 5025. 4.95 Sine* 1931 Radio Stitch h»s b««n th« ptBc« lo obtain up-io-diie elcctfonic ptns u MS quality tools, test «quipcn«nt uid accessaries at low pHee^ Nearly 7000 tocitjorH ire r««dy te wrvm you— COIIPAI^ES RS-332 Tester. Dual -color LEDs monitor seven data/ control lines to help you spot prot^tems quickly. D-sub 25. Connects inline. #276-1401, 14.95 (1} Binding PolU 10 BHC Mile. i?74 715 S,9S m Blr^dtng Poit fo B«nDna Pluga, if??A 7}fi, Set (3} Duil Ban anil Piug^ Accepis test probos, wire and^cr binina plug^ •274-717 . . 2.M Deluxe Breadboard. Our bestt Molded 2 V-* xB'h' board is mounted on a 7 X 4" stool base with stabilt^ing rubber feet. Features 640 plug -In points and three binding posts. ^^276-169 19.95 Breadboard Jumper Wire Kit. In- cludes 140 insufated, preformed. Stripped wires in a snap-shut plastic IJOK. #276.173 . , . . . So! 4.95 . Radie/haek' — MMSttCM'S rmOHMOLOCY STORE StMCE fBSt CnCLE 7S OH FREE INFaftMATIOM CABD CAR STEREO AMPIJFIERS AHOUND. but most are compromises in performance, or are expensive. Our build'it-yourself car ampli- fier is a real goose-bump gener- at on offering performance In the high-end home-stereo range* yet Is cost-effective and easy to build. Performance highlights include 270 watts output power (135 watts per channeL RMS, into 8 ohms), low distortion ♦ and exceptional output current capabilities. The power supply itself Is capa- ble of delivering over 600 watts, giving the amplifier plenty of re- serve power. Note also that the power rating is for real, contin- uous watts, into 8 ohms (not the way most car amps are rated), allowing the use of home-system speaker compo- nents, which are generally less expensive than 4-ohm versions, and offer a much broader selec- tion of quality elements. If 4- ohm speakers are desired, the amplifier will deliver a whop- ping 200 watts per channel! Tci- ble I shows the amplifier's spec- ifications, and Fig* 1 shows some output waveforms. BUILD THIS HIGH POUJ€R HI-FI AUDIO mp FOR YOUR CAR Our build-it-yourself car amplifier lias so much power that it ought to be illegal! |||^>yerall design Along with high perfor- mance, another design goal was that the amplifier be easy to build. That was ac- complished by using a custom heatslnk and a single PC board. The heatsink allows the mounting of all power semiconductors with simple snap-on fas- teners, and the PC board accommodates both amplifiers (left and right) and power supply Also, all compo- nents are board-mounted minimizing point-to- point wiring. An on- board power relay eliminates the need for an external high-current switch, and allows the amp to be slaved to an auto ra- dio's power-an- tenna lead. Both the power REINHARD METZ and MYZIL BOYCE 31 n h A p- i W\/\A7 • I- 9^4 ^MidU 4B4 =4 us Ov^rsnjot 5,3 El S2 C ~ Input at Par iQd Pissume 59 j £'9 ill rill \ I ima " u r'l Vp-P Oversr);ycl 14,0 :! 1^ f^e-'l ^cqui t1 t, ion I J n^l OUTPUT IKPUT tv/oiv FIG. 1— OUTPUT WAVEFORMS, rn a. the ampJifier is driving an 8-ohm load on both channels at 1 kHz; the signal clips at 93 volts p-p with 135 watts per channel. Both channels are driving a 4*ohfri load at 1 kHz in b; it clips at 81 volts p-p with 200 watts per channel. Using an 8-ohm load with the input filter removed, a rise time of 600 ns and a slew rate of 54 volt&^s can be seen in c. supply and the amplifiers use sUilc!-or-Lhc-art ficid^effect power transistors (FETs). A custom copper-lape-wound in- verter transformer gives the power supply its puncli. A CAD- supported printed-circuit board with ground plane, plated-th rough iioles, sllksereened parts placement, and solder mask completes the picture. Lets take a more de- tailed look at how the unit works* Tbe power supply Figure 2 shows the power- supply schematic. The basic de- sign is a push-pull fonvard in- verter with pulse-widtfi modu- lation voltage regulation. Relay RYlOl is energized via the 12- voli control lead, applying power to the pulsewidlh-mod- ulator chip ICIOI and the power transformer center tap. Alter- nating pulses generated by ICIOI driv^e the output tran- sistors at pins 16 and 13. turn- ing on QlOl and Q102. and Q103 and 9104. one pair at a time. The transistors are paral- leled for Increased power han- dllng capacity. Resistors R107-R110 eliminate the pos- sihility of local transistor os- cillation. As the transistors alternately conduct, an alter- nating current flows in the pri- mary of transformer TlOl, in turn inducing an alternating current In the secondary. The output of TlOl is full- wave bridge rectified and then filtered by LlOl, L102. C106, and C107. With a winding ratio of 4 to h a maximum of about 58 volts can be generated at the output. That is regulated down to i 47 volts by sending a sam- ple back to resistor divider RU2 + R1I3 and R105. The di- vided voltage is applied to pin 2 of ICIOL where it is compared to a 2 , 5* vol I reference, generated In turn by dividing the chip-pro- vided 5-voU reference at pin 10 by RlOl and R102. When the supply output drops below^ 47 volts. ICIOI drives the tran- sistors with longer pulses, and with shorter pulses when the output goes above 47 volts, thus achieving voltage regulation. Components C102. C103. and FIG. 2— POWER SUPPLY SCHEMATIC, ft s a push-puH forward inverter with pulse- widlti modulalion voltage regulation. Relay RY101 is energized via the 12-volt control lead, applying power to the pulse-width-modulator chip IC101 and the power trans- former center tap. a2V C8 Dt 1H4744A 15V ji CI INPUT lOpF -IF I 10K R24 ^ 4 RZ5 2.05K CI C3 6BpF R5 5.11K R4 IK R12 51 1U R2 C7 Ji D2 ^ 1K4744A 15V R3 Ra7 2.05K 100Q D5 1N4737A 7,5V R20 05 —^5^^ Q2 /MPseaaa L*J .1 a2v mi IK R1S 5tia fi22 20.5Q D6 1ia737A 7^ 010 [RFe4Q F1 ;4 AMPS -I- 47V -0+ ^ OUIPIJT 1- -47V AMPS ^C8 4 FIG, 3— THE LEFT AND RIGHT AMPLIFIERS are identical and the parts numbered the same except for an L or R suffix; here's one of the amplifiers. jo JP o Q a 33 R103 form a filler network thai stabilizes the voltafje-regulation feedback loop. The inverter op- erating frequency is set via C104 and R106 to about 50 kHz, Finally, LI 03 keeps noise from the inverter from getting back into the car power system, and D105-D107 form a snubber network that limit*s ringing volt- ages generated by the alternate ing high currents in the transformer primary The amplifiers Both amplifiers (left and right) are Idem teal, and parts are numbered the same, with an L or R sufUx. as appropriate. Therefore well show only one of them — see Fig. 3. Input signals are applied to ICK an LF357A op-amp. via filter network RL R24. R25, CL and C2. The out- put of ICl drives resistors R9 and RIO. which are in series with current source Ql and cur- rent sink 92. The result is that voltage swings al the outpul of ICl (at pin 6) are traYislated and applied to the bases of Q5 and 96, The DC voltage between the bases of Q5 and Q6 is set by voltage multiplier Q3, The volt- age is nominally about 8 volts, and can be sel as desired by R16. It appears across R13 and R14 by emitter-follower action of Q5 an Q6, In turn, a current nows through R12 and R15, generating a voltage across them, which is applied as the bias for the output transistors. FET output transistors Q7-9 10 each require about 3.5 volts bias from gaie-to source to be* gin conduction, which is sup- plied as described above. The output transistor bias is ad- justed to provide an opttnial idle current in the output stage. To keep that current stable, the output transistor temperature is sampled by Q4. which is mounted on the heatshik, and the Q3 bias generator voltage is varied to track the temperature accordingly Transistor 9^ has its gate connected to its drain, causing the drain-to-source voltage to be roughly eqtial to the gate turn-on thresliotd. which varies with temperature and tracks the output transistors, IVan- sistor 93 multiplies that voltage by a factor of two. to provide the bias required l>y both the positive and negative output transistors. Tfc-ansistors QS and 96 also provide a phase-inver- sion function, taking ihe AC signal voltage at the output of ICl and applying it to the gates of the output transistors. As the gates are driven, the drains, connected to the output, swing In Ihe opposite direction, driv- ing the load. Components C4, R18, and R19 form a local feed- back loop, selling the output stage gain at about 15, Compo- nents C3, R5, R4, and C7 pro- vide overall amplifier feedback, and set the total amplifier gain at about 5L Zener diodes D5 and D6 limit the outpul tran- sistor gate drive voltages, which in I urn limit the maximum out- put current. Building the amplifier If you are fabricating your own circuit board, remember thai you will have to provide feed-throughs and solder com- ponent leads on both sides of the board in several places. We've provided foil patterns if you want to do that, but you can also buy a ready- to- use PC board, as wcl! as various other parts, from the source men- tioned in the [iarts list. Figure 4 is the parts placement diagram. Begin assembly by installing all parts except the TO-220 power components and potentiome- ters R16L and R16R. Carefully verify resistor and capacitor val- ues before Installing them, and check diode and electrolytic ca- pacitor polarities. RG. 4— PARTS PLACEMENT DrAGRAM. First install atl parts except the TO-220 power components and poienliometers R16L and Rt6R, Before installing the output FET s, they fnost be matched in pairs within each particular type (see text and Fig. SJ. Before installing the output FETs, they must be matched in pairs within each particular tvT^e to ensure proper current sharing and power dissipation. As an example, Q7L and Q8L must be niatctied to each othen but the}^ don t have to match the ri^ht -channel components, (Q7R and Q8R must. oC course, ma tell each other.) The same goes for Q9 and QIO. A simple circuit for matching them Is shown in Fig. 5. The parts should be matched to be within 100 millivolts of gate voltage at 50 mA of drain current* and 200 millivolts of gate voltage al 2 amps of drain current. Make the 2-amp measurement quick- ly — otherwise you must heat- sink the transistor. Note that 1^- channel devices (the lRre640s) must be supplied with - 5*volts DC and N-ehannel devices (the lRF640'sl must be supplied with -f5-volts DC. Once you have matched the FIG. 5-PAIRS OF FET S MUST BE MATCHED using this circuit (see te^t)* First set the potentiometer's wiper volt- age to zero, turn \K up to the desired drain current, and measure the voitage as shown. Match the parts to within 100 mll- livoHs of gate voHaga at SO mA of drain current, and 200 miHivoUs of gate volt- age at 2 amps of drain current. Ivhchan> nel devices (the IRF640S) require a * 5- volt supply^ and P-channel devices (the IRF9640'3) require - 5 voils. transistors, insert them in the PC board. Make sure Ihey are straight up with their leads pn> truding uniformly about Vie- Inch from the bottom of the board. Check to see that the transistors are centered on the lieatsink rail, and then solder. Next, prepare potentiometers R16L and R16R by adjusting them for a resistance of 1000 ohms between pins 1 and 2 (see Fig. 6), and then install them. Finally, install the three power and ground lead-in wires, as well as the speaker outputs and grounds. Check that all parts are the correct type and value, and in the correct orientation. Chassis assembly Prepare the heatsink by checking to see that the mount- ing surfaces for the power com- ponents are clean and smooth. Temporarily slide the circuit board assembly into the heat- All resistors are Vi-watt, S%, un- less otherwise noted. R1, R6, R7 (two of each. L&R). R101. R1 02— 10.000 ohms R2. R3, (two of each, UR) 2050 ohms. V2-watt R4, R19. R26, R27 (two of each, L&R}— 100 ohms R5 (two. L&R>— 5110 ohms R8, R11 (two of each, L&R}— 1000 ohms R9, RIO. R17, R24. R25 (two of each. L&R)— 2050 ohms R12-R15 (two of each, L&R)— 511 ohms R16 (two. L&R)— 5000 ohms, potentiometer R18 (two. L&R}— 1500 ohms R20-R23 (two Of each. L&R), R107-R11 0—20.5 ohms R103, R1 04— 24.900 ohms RI05— 5620 ohms R1 06— 14.000 Ohms R111— lOohms, 1/2-watt R1 12— 75.000 ohms Capacitors CI (two, L&R)— 10 ^JlR 35 volts, eJectrolyiic C2, C4 (two of each, L&R)— 0,0015 jx R ceramic C3 (two, L&R)— 68 pR ceramic C5. C6. C8-CtO (two of each. L&R} . C104— 0.1 |iF. Mylar C7 (two. L&R}— 100 10 volts, electrolytic PARTS LIST CI 01, 01 05— 1000 jxR 15 volts, electrolytic 0106, 01 07— 1000 |iR 50 volts, electrolytic 01 02— 2.2 |iR 15 volls. electrolytic 01 03. 01 08—100 pR ceramic 0104—0,001 fiR ceramic Semiconductors 101 (two. L&R}— LF357A op-amp IO101— SG3526N pulse-width- modulator D1. D2 (two of each, L&R)— 1N4744A €\o6b D3-D6 (two of each, L&R)— 1N4737A diode D101-D104— FR805 diode D105. D106— 1N4002 diode D107— 1N4752A 33-volt Zener di- ode 01, Q6 (two of each, L&R)— MPS8598 PNP transistor Q2. Q3, Q5 (two of each, L&R}— MPS8098 NFN transistor Q4 (two, L&R}— IRF510 N-channel MOSFET 07. Q8 (two ot each, L&R)— IRF9640 P-channel MOSFET Q9. QIO (two or each. L&R}— IRF640 N-channei MOSFET Q101-O104— IRFZ40 N-channel MOSFET Other components LI, L^— 28 ^^H coil L3— 10 ilH coil RY101— T90N5D12-12 relay (Potter and Brumfield) T101 — Iransfonner. 4 turns, center- tapped primary. 16 turns, center- tapped secondary; 5-mil copper- foil wounded on a Ferroxcube ETD-34 core. F101— 30-amp fuse F1, F2 (two of each, L&R) 4-amp fuse J1, J2— RCA-type input jack Miscellaneous: PO board, 16 "0 ' clips, 16 insulators. 10 fuse clips, heatsink/case strain relief, 4 "L" brackets, wire, solder, etc. Note: The following Items are available from A&T Labs, Box 4884, Whealon, IL 60187: • Complete kit of parts includ- ing heatsink and covers, PC board, and transformer- S245 • Fully assembled and tested unit— $315 • PC board (Mlhspec glass, double-sided, sllkscreened, with solder mask)— S29 • Transformer T1— S40 • Custom heatsink with covers— S44 Please add 5% of total order for shipping and handling, 12% in Canada. IL residents must add 7% sales tax. Check, money order, or CCD. in conL U.S. AH inquiries must include a SASE. sink. Install the endplate with the input connector holes, and slide the board up against it. Tkke a look at Fig. 7. the inside of the author's completed pro- totype, to get a feel for the over- all assembly and close-up de- tails. Lightly mark each power component site on the case. Re- move the ampUlicr and prepare each site with a thin coat of thermal heats hi k grease. Apply a mica insulator at each site. TABLE 1— SPECIFICATIONS Power Output 135 watts^channel RMS into 8 ohms with both channels driven 200 watts channel RMS into 4 ohms with both channels driven Frequency 12 H2-45 kHz ( 4^ 0, - 3 dB) Response 12 Hz-400 kHz with input filter removed Distortion <0.03% THD at 1 kHz. <0. 1 % 20 Hz-20 kHz Rise Time <0.6 ^is Slew Rate >100V/|is Power Input 12-14.5 volts, 0.5 to 50 amps maximum FIG. 6— PREPARE POTENTIOMETERS R16L AND R16R by adjusting them for a resistance of 1000 ohms between pins 1 and 2. Re-install the amplifier board with each of the power parts bent slightly away from the heatsink surface. Apply a thin layer of thermal grease to each part. Then bend the part back against the heatsink. and hold it in place with a spring clip as shown In Fig. 8. Use a piece of cardboard or plastic as an in- sulator between the part and the clip. After each clip is In place, remove the two wire bales from the clips. Make a final check with an ohm meter to see that none of the power parts are shorted to the heals Ink. We are now ready to make a few safety checks on the circuitry. Tfesting install a 5-amp fuse for FIOL and apply power The inverter should now generate plus and minus 47 volts, as measured at the fuse clips for Fl and F2, Now install a 1-amp fuse for FIL and a milliam meter for F2L. Apply power and adjust R16L for a cur- coutinucd on pngc 74 HlttCD ^^^^^ ^1 U -11>/< INCHES - COMPONENT-SIDE FOIL PATTERN shown half-size. ^ ==il». If I -1t>/i IMCMES- SOLDER-SIDE FOIL PATTERN shown hair-size. O SNOOPER STOPPER o IN _ Q^J NOTCH m DEPTH FREQ BUILD THE ^noopER STOPPER An easy-to-build filter rejects cable TV signals that interfere with your FM^and stops the infamous ^^bullet/^ EDGAR WOLF C/\I3LE TV SERVICES HAVE COME A long way since they put anten- nas on hilltops to relay pro- grams to customers hidden In radio "shadows/* People sub- scribed to what used to be called community TV because they had to. not because they wanted to. But now this has all changed: Cable W offers scores of channels and special pro- grams not available from com- mercial channels for a monthly fee. The latest estimates place the number of homes in tJie U.S. with cable TV at 52 to 53 million, an astounding 61% of all homes. However CATV has become a victim of its ouTi success. Many people want the programming but are unable or unwilling to foot the monthly bill. So many have turned to **pirating" the programs with unauthorized converters. Not surprisingly the cable TV companies are striking back at unauthorized (nonpaying) users by charging them with "theft of service." Ac- cording to the National Cable Television Association (NCTA). U.S. cable companies lost S3 billion in revenues because of pirating in 1991. The cable companies have de- veloped countermcasures to root out offenders. These in- clude the infamous "bullet" (see Radio-Etectronlcs January 1992,) and distinctive give-away identification signals. Both are sent out to customers over their cables. The selective "bullet* will zap a 37 only unauthorixed TV convert- ers or descramblers hooked up to the cable, and the identtfica' lion signal, which sounds like a cuckoo at about 108 megahertz on the FM band, presents no threat to paying customers. The bleeping "cuckoo" signal leaks from unauthorized converters and can be detected by cable company personnel monitoring a suspected pirates house with handheld receivers. Unfortunately, both the "cuckoo" identification signal [if used) and routine command signals sent by the cable compa* ny over their cables lo set up converters in customers' homes can cause interference with FM reception In those homes. To prevent the signals from inter- fering with your FM reception— and to ward off a "bullet" — you can build this passive filter called a Snooper Stopper. Addre ssability Cable operators have the abil- ity to control Individual sub- scriber service from the head end in fully addressable sys- tems. This permits prompt ser- vice changes and reduces tam- pering problems with converter computer control by identifving and "tagging" each channel so that specific programming can go to the authorized subscriber. Each cable TV converter has its own unique identification code. When you change from one pay service to another or request a pay-per-view program, that unique code identifies your converter. The code is first sent to access your converter to pre- pare it for data that is to follow The data includes Instructions that set up your converter for the programs you are autho- rized to receive. Data channel With fully addressable sys- tems, cable TV companies send setup data to your converter over the cable with an FM signal called a dutit ch^umcL This is done by frequency modulating the data at 106.5 MHz. Cable companies use addressable converters because they are cost effective and convenient. Wlien a customer calls for a change, or CABLE m > m RECEIVER FM I SPUTTER I CABLE TV CONVEHliR TO Fie. 2— SCHEMATIC OF THE SNOOPEfl stopper, actually a band-rejection filter known as a bridge-T trap. Jl -L3- U J2 FIG. 1— TYPICAL INSTALLATION of a cable TV converter, FM receiver and an FM splitter orders a pay-pcr-view movie, these instrucUons can be car- ried oul au tomat icatly by the ca- ble company's computer. How- even not all homes with cable TV have addressable converters yet. Some cable companies have added the chirpint; cuckoo-like sound at 108 mefjahertz. The "cuckoo" signal rides along with the command signal at 106.5 MHz. Therefore, noise might show up at several .spots on your FM dial. This is caused by what has been referred to as "channel splash" due to the high energy level of the signals being sent. If you want to find out if your cable system is addressable and thus the source of superfluous noise, you can hook up your FM receiver lo the cable TV system as shown In Fig. 1 (if it is not already connected K Next scan the FM band to pick up any beeping noise and record the dial setting at which it is stron- gest—most likely around 106,5 megahertz. However, noise could also occur around chan- nels 59 and 60 on your cable converter. If you detect the beep- ing signal at any of those points , the Snooper Stopper will elimi- nate the noise and prevent you from being a target for sur- veillance. In addition, the Snooper Stopper is an elec- tronic shield thai will block the •*bullei." Circuit description Th e sc h e ni at i c o f ou r S n oope r Stopper is shown in Fig. 2. It is a low-cost passive band -rejec- tion (notch) filter known as a bridge-T trap. The iiUcr. olTering a notch depth of 40 to 60 dB, has only one resonant circuit — CK C2, Lh and L2— making it easy to tune. This bridge-T trap FIG. 3— PARTS-PLACEMEI4T DIAGRAM for th€ Snooper Stopper. Install all com* ponents as shown here, uses a tapped inducton Trim- mer potentiometer Rl permits critical adjustment of notch depth. Althou^li a bridge-T trap provides sufficient signal at- tenuation, its band (notch) wid- th is not verj^ precise. Snooper Stopper's perfor- mance on systems with single interfering carriers is good, but with duai carriers, calibrating tile notch frequency is critical. For this reason* trimmer capac- itor C2 is included for tuning throughout the entire band, while RI is used to adjust the notch depth. Building and adjusting [f you wisli to make your own PC board, use the actual size foil pattern. Refer to the PC board layout shown in Fig. 3, and mount all components as shown. Be sure to install the F- PARTS UST Resistors R1— 500-ohm potenlrometef Capacitors C1~1 to 10 pR adjustable, Johan- son type #8052 or equivatent C2— 12 pF NPO Inductors L1— 0 .15 jiH, fixed corl L2. L3— 0,049 m^H. fixed coil Other components J1, J2— F*type RF jack connectors for circutt-board mourtting with ring nuts Mtscelianeous: case (Radio Shack Cat. No. 270-231 orequiv- aient). Note: The foliowing items are aval table from Northeast Elec- tronics Inc., RO. Box 3310, N. Attleboro, MA 02761, (1-800-886-8699). Check, money order, Visa and Master- card accepted. Massachusetts residents must add 5% sales tax. • A kit of parts including an etched and drilled PC board, all components, and a plastic case with aluminum cover — $19,95. • An etched and drilled PC board— S7 .95, • A kit of just the parts (no board or case)— S15J5. Ptease add S4.50 S&H to any order i^QUENGY ADJUST CI OtflPUT GROUND FIG. 4— TH E AUTHOR'S PROTOTYPE re- moved from the case and wilhout the cover plate. -VVitr- FIG. S^HOLE-ORILLING TEMPLATE for aluminum cover of recommended plas- tic case. t\pe RF coax iai jack connectors and trimmer potentiometer Rl so they face up on the PC board as shown In Fig. 4. When the components have been posi- tioned and soldered^ check your work carefully looking for sol- der bridges and open traces. Next, use the template (Fig. 5) as a guide for drilling the four holes in the aluminum cover of the recommended case. The same template can be used for drilling the holes in an alternate case cover by centering it on the coven Be sure that the alternate case has sufficient volume to contain all of the circuitry' with- out interference. Install the completed Snooper Stopper as shown in Fig. 6 and tune it for the nuisance noise» Adjust C2 (frequency) and Rl (notch depth) until the interfer- ing noise is blocked from your FM recei^^e^. Do not use the Snooper Stop- per to circumvent the cable company's right to de-authorize your converter. Along with blocking a destructive "bullet," the filter will also prevent all pro- gramming instructions from reaching your cable box. If you install the Snooper Stopper ahead of the cable company *s converter and change services, you will have to remove it so the converter can receive new in- structions* Some new convert- ers shut down if data is missing for long periods of time. R-E 2N0 CABLE TV COfJVERTrR N TO 2ND TV iSTCABLeTV COMVERTtR TO 1ST SOLOER SIDE foil pattern for PC board shown actual size. FIG. e^lNSTALLATION OF THE SNOOPER STOPPER ahead of the FM receiver and a second cable TV converter. 6 Electronic Temperature Measul^eAt No study of electronic temperature measurement would be complete without showing some actual circuits. HffR AST MONTH WE CLOSED VVITK A iook at thermistors. Lets con- Ifnue with some basic cir- cuits—some fhermisior ap* [jhcaLion csrt^uUs to start off with. In the Wheatstone bridge <)\ Fig. K the thermistor resis- tance decreases as temperature goes up, raising Vout = R3, Vq^jt^ will be zero at the tem- perature where the thermistors resistance equals R2. The output can be made lin- ear ifR I is chosen correctly. As i i turns out, the NTC (ne^iativr temperature rocrnaent) lIri- mislofs norilmearity is largely £x>mpcnssrte?l for by the non- linearity ol' the bridges own vni { age-versus-resistance t :uii.c. Figure 2 shows the volt- age versus temperature curve fairly linear in the middle of its range, dropping in sensitivity at both ends. We won't take the lime to prove that here, but the best possible linearization oc- curs if Rl is equal to; where R r R^ 2^ ^nd R-r are the 40 thermistor's resistance at tbe low end, midpoint, and high end of the temperature range re- spectively (Remember R^i Is higher than RY L TRIETLEY Vou c^n see by looking at F 2 thai thedeviation from per^t linearity i^^ts worse as the perature rahge widens, JjKe ta ble in Fig. 1 includes calculated values for three L>picai ranges, and Table 1 gives R versus T data for the thermistor Ranges oi' equal width centered at dU- ferent temperatures wiU hnvc siinHar nonlincariMes. For ex- ainplt . i! properly designed 50 to H)fJ C range will be about as nonlinear as 0 to 50^C. A thermistors sensitivity clianges greatly with tempera- ture, making it difficLili to lin- earize one over Its entire ftUlgtr. Even digital techniciues are (dif- ficult, requirinii a lari^e number of bits in the A^D converten One trick is to use two thertijistors, one with low resistance for op- timum low-temperalure re- sponse, and the other with higher resistance for tilgh tem- peratures. % Figure 3 shows such a cTrcui t . At ver>^ low temperatures R^.^ ib so large that R^*, and R2 clomi- nate. At higher teni[Jt'rii[ m rs the opposite is true: R,., br- comes small in com part son with R2, and Ry^j^ shunts ihe R2-RT^t combination. If the component values are properly chosen, R-1-2 begins to make a pticeable contribution just as I begins to fall off. The values in Fig. 3 yield better than i:0.22°C linearity from ft, lOO'^C if the proper thermistor pair is used. 'T\vo-Lliermistt)r composites cuntafning two precision discs encapsulated in one epow case are available from YSI in Yellow Springs, Oil and Fc nwal in Milibrd. MA. Figure 3 uses Oie most common, available in YSVs lamily of 700-Series prnben, '1^- bli^ 2 shows its R versus 1 Lies. Resistor selection is no easy and is usually done using a computer. The manufacturers offer precalculated values for several temperature ranges. The concept also has been ex- tended to three-thermistor net- works- RTD% A resistance thermometer, or RTD (Resistance Temperature Device), Is simply a wi rewound coil or metal lilm whose resis- tance increases with tempera- Lure. As we saw last month, platinum is the most widely used materia^ offering tlie best siahihiy and widest (einpera- ture range, w^h He nickel is some- times used for moderate indus- trial temperature measure- ments. Platinum thermometers are sometimes known as PRTs (Platinum Resistance Tlier- mometerst- Table 3 gives R versus T tables and tj^ical accuracies for plati- num and njci^ei RTDs per the German DIN (Deutsche Indus- trie Normenausschuss) stan- dard. Other curv^es exist, but those In 'Ihble 3 have achieved world -wide recognition. Most manufacturers offer platinum matching the DIN R versus T tab^. but often with tighter or IooJbt accuracies. Not all plati- ninAhcrmometers cover the entlft - 200 to 850"C range, and a 500 Qr 600'C upper limit Is common* Sensors of 100 ohms (at OT) are most common, but others exist. At 100 ohms, platinum's sensit ivitv is 0,385 ohmsf C be- tween 0 and tOO'^C, decreasing sHghtly a$ itemperature rises. Nickel'!^ sensitivity Is 0,618 olims/'C, increasing with tem- perature. Higher resistance sensors provide proportionaliy higher ohms per degree. Platinum is expensive, but very little metal is used in mak- ing RTDs. TNpical 100-ohm ele- ments use about 22 inches of O.OOl'inch diameter wire wound on a small ceramic bob- bin. Manufacturing details vary, but the wire must be con- strained well enough to avoid shorts between turns, yet free enough to minimise strain- gage effects due to thermal ex- pansion. The finished elpment is usually encased within an outer ceramic or glass housing. Most e!ement|fare un(|er Cl- inch diameteyand a f ration of an inch lon^ Figure 4 shows some typlca^elements. The'biggest challenge for manufactuiers is acciuncy* and 0*25^C actiiracy corr^ponds to 0.1% resistance, or altout 0,022 inch of wire. Some ^manufac- ture rs carefully control the wire Iciigtli while others have de- veiujjcd methods lo trim at a known temperature. The wire composition itself must be care- fully controlled: very slight amounts of impurities are al- loyed with the platinum to achieve the correct temperature EXAMPLES OF BRIDGE DESIGNS Temperature range 10 to 30 C OtoSOC OtOTOC Temperature for 2ero ou^ut lire (TC Sensitivrty 10 mV/^ lomvn: lOmVX Bfidge supply (V.) 916.2 mV 1017.3 mV 1147.0 mV Rt 2,158 Ohms 1 ,763 Ohms 1,164 ohms R2 4,482 ohms 7,355 ohms 7^355 ohms R3 2,168 Ohms 1,763 Ohms 1,164 ohms Ma)(lmym nonllnearlty ^ 0.07 -0.06'^C -^ 0.85 -0.95^C t 2.0 - 2.3X Note: Thermistor is a YSI ^4004, 400 series probe or equivalent, 2,252 ohms at 25'C FIG. WHEATSTOKE BRIDGE with a thermistor arin will produce an output ttiat fncrsases with temperature. The table shows three practical ranges. ^ V3 5 V2 o UJ ACTl lAL — — \ to EAL T \ — I ■ ■ I -h 1 \ 1 r J. TEMPEFWrURE RG. 2— THE WHEATSTONE BR(DGE OUTPUT Is talrly linear near the middle of its range. coefficient. Pure platinum sen- sors having slightly higher sen- sitivity arealso avallalile, Platinum*film elements are a more recent development. Most are made by vacuum-depositing platinum onto ceramic sub- strates, although silk-screened thick-film pastes have aJso been used. Film elements are not as stable as wire at high tempera- tures, but they cost less. Depos- ited film uses less platinum and can be bulk manufactured and FIG, 3— A THERMfSTOR-PAIR can be used in a Wheat stone bridge to improve the output linearity. This circuit is linear to within -0.216 C from 0-100 C. laser trimmed. The elements can be made smaller — as small as thermistors — and can be supplied in resistances to 2 kil- ohms lor higher sensitivity. Copper, in general, is a poor choice for temperature mea- surement due to its limited tem- perature range and ver\* low resistance. Us most common application is monitoring the temperature rise of motors, generators, and transformers. Other alloys have been used to create RTDs. but we will not cover them !ierc, F^TD elements can be as- sembled Into a wide variety of probes, as can thermistors and thermocouples, including some with threaded fittings for [>er- manent installation into indus- trial processes. A pointed probe could be used to monitor the cooking or refrigeration of foods, while a Hat probe (made from a film element! could be used to measure surface tem- peratures. Other styles are available, including laboratory iypcs and probes with bends. RTD cirettits RTD readout circuits are basically ohmmeters, spe- cialized to ignore lead-wire re- sistance and (sometimes) lo compensate for R versus T non- linearity. Since t^'pical RTD sen- sitivities are 0.4 or 0.6 ohms per degree, each ohm of lead resis- tance contributes about 2^C measurement error Therefore, compensation circuitry must be used. Four-wire resistance mea- surement completely ignores lead resistances, but three-wire compensation circuitry is more common. (An extra uire can be expensive in an industrial in- stallation!) In Fig. 5*a, four-wire (also known as Kelvin) circuitry uses one pair of leads to excite the sensor witii a constant cur- rent and a second pair to mea- sure its voltage drop. The voltage drops across the excita- tion leads are not seen by the differentia] amplifier, and the measurement leads carry es- sentially no current, so their voltage drop is zero. Therefore, the amplifiers input sees only the voltage drop across the RTD itself The circuit also performs linearization, but we'll come back to that in a moment. The three wire circuit in Fig. 5-b uses an identical controlled current source but different readout circuitry. The main am- plifiers " -h " input sees the com- bined voltage drop of the f^TD and the two excitation leads. The second ( x 2) amplifier sees PIG. 4— TYPICAL RTD ELEMENTS, with teads attached. The small square efement toward the right of the picture is a platinym-filfn element (Courtesy of Sensing Devices Inc.) COHTROLLED^ SOURCE ' I 4- VOLWE» REFEBENCE VOiWCE SLIGHT > POSITIVE >^ FEEDBACK ^ HfiEARIZES PUTtHUM RTD OIFFEREWTIAL AMPLIFIER _ho OUTfUTti G X I X RTD .VOLTAGE- I ^ VOLTAGE I 1^1 X (RTD + 2R,„„) — <1~r FAGE ^ ^s. _ RfiFfREWCE " VOLTAGE o OUTPUT = G X I X RTD . VOLTAGE = 2 X I X R^£((5 FIG. 5 — FOUF^-WIRE MEASUREMtNT (a) measures the RTD's resistance and ignores lead wire resistances completely; it also includes linearization for platinum RTD's. Three* wire circuitry (d) compensates for voltage drops in the lead wires. TABLE 2— JOO-SERIES THERMISTOR PAIR Temperature T1 (Ohms) T2 (Ohms) F (6K at 25 C) (30K at 25 C) -30 (-22) 106.2K 481. OK -20 (-4) 58.26K 271.2K -10 (14) 33.20K 158.0K 0 (32) 19.59K 94.98K 10 (50) 1 1 .94K 58.75K 20 (68) 7496 37.30K 30 (86) 4834 24.27K 40 (104) 3196 16.1 5K 50 (122) 2162 10.97K 60 (140) 1493 7599 70 (158) 1051 5359 80 (176) 753.8 3843 90 (194) 549.8 2799 100 (212) 407.6 2069 TABLE 3— PLATINUM AND NICKEL RTD S (DIN STANDARD 43760) Temperature -200 -too -60 -50 0 50 100 150 180 200 400 600 800 850 Platinum (Ohms) 18.49 60.25 76.33 80.31 100.00 1 1 9.40 138.50 157.31 168.46 175.84 247,90 313.59 375.51 380.26 Tolerance (^C) 1.3 0.8 0.6 0.55 0.3 0.55 0.8 1.05 1.2 1.3 2.3 3.3 4.3 4.55 Nickel (Ohms) 69.5 74,3 100.0 129,1 161.8 198.7 223.2 Tolerance 2.1 1.8 0.4 0J5 t1 1.45 1,7 TABLE 1— CHARACTERISTICS 2252-OHM PRECISION THERMISTOR Temperature Resistance C F Ohms -80 (-112) 1660K -70 (-94) 702.3K -60 (-76) 316.5K "50 (-58) 151 OK -40 (-40) 75,79K -30 (-22) 39 86K -20 (-4) 21 87K -10 (14) 12-46K 0 (32} 7.355K 10 (50) 4.482K 20 (68) 2.814K 25 (77) 2.252K 30 (86) 1.815K 40 (104) 1.200K 50 (122) 811.3 60 (140) 560.3 70 (158) 394.5 80 (176) 282.7 90 (194) 206.1 100 (212) 152.8 110 (230) 115.0 120 (246) 87.7 130 (266) 67.8 140 (283) 53.0 150 (302) 41J only the IR drop or the lower ex- citation lead. The x 2 amplifier doubles thai voltage and pre- sents it to the main aniplilier, which subtracts it from the total. Thus, the signal seen by the main amplifier is (I x (RTD + 2Ri^,,,,j,)) - (2 X I X R,.hadK which equals I x RTD. Compen- sat ion will be perfect as long as the resistances of the leads and their connections are equal* Now back to linearization. Platinum RTDs decrease in sen- sitivity [ohms per degree) as temperature rises. That can be compensated for by causing the current source to increase slightly with temperature. !n Pig. 5-a, a slight amount of positive DC feedback (much too small to cause oscillation) in- creases the controlled current source as the output rises. Figure 6 shows a practical cir- cuit. The controlled current source consists of ICl-b and Ql ; ICl'b compares the voltage drop across R2 lo the voltage on R7s wiper and controls Ql lo keep the two equal. Resistors R3 and R4 "pad" the value orR2: when properly adjusted » the net resis* tance of R2. R3. and R4 is 100 ohms. Filter R5-C2 removes 60 Hz or other noise picked up by the RTD leads. The main ampll- fien IC2, is a differential ampli- fier with a gain of h The positive feedback from R16 increases the RTD current with output, linearizing the platinum cuht to better than ±0.5°C between 0 and SOO'^C. Linearization de- grades somewhat at higher and lower temperatures. Components ICl-a. RIO, and Rl I form the x 2 ampllfien with Rl and CI providing filtering. Notice thai ICl-a amplifies the voltage drop across R2 as well as that of the current-carrying lead. Us output is: 2xix(Ri.KAD+ loon) Now notice that the main amplt- fiers input is: I X (RTD + 2RLEAn + lOOfl) IC2s output is the difference: 1 X (RTD - lOOfl). Since the RTD is 100 ohms at 0°C. the output at zero degrees is zero millivolts* With the circuit v^alues shown, sensitivity is 1 mV/^C. which is handy for measuring tempera- ture with a DVM. Zero is set by providing a 100- ohm input and setting R4 for a 0-mV output. The gain is ad- justed via R7 for 500"mV output at 280.90 ohms {500X). Be- cause RTD's are interchangea- ble, you do not need known temperatures or a reference thermometer for calibration. Thermocouples A thermocouple is simply two unlike metals joined together. The junction produces a voltage that increases with tempera- TABLE 4— STANDARD THERMOCOUPLES Thermocouple Type Base Metal Thermocouples: J: Iron vs. Constanlan K: Chromel vs. Alumel T: Copper vs. Constanlan E; Chromel vs, Constantan N: Nicrosil vs. Nisil Specified Temperature Range -210 ID 760"C -270 to 1372°C -270 lo 400^C -270 10 l OOO^C -270 to 1300=0 Specified Error (Above 0 C) Applications Platinum Alloy Thermocouples: R: W13% rhodium - 50 to 1 7e8'C vs. pure pi. S: Pt/10% rhodium vs. pure pi. B: mO% rhodium vs. pl67o rhodium. (Same as type R) Oto 1820^C S(d: Z2=C or .75% Special: l .r C or .375% (Same as type J) Std: 0.83°C or 75% Special: 42X or ,375% Sid. 2.2^C Of ,5% Special: i.VC or .375% Sid: 2.2=C or J5^b Special: 1.1 X or .4% 1,4Xor0.25% Reducing and inert atmospheres. Avoid oxidation and moistum. Oxidizing and inert atmospheres. Most atmospheres. Best choice below 0 C. Moisture ok. Oxidizing and inert atmospheres. Highest sensitivity Hi temp and oxidizing. More stable than type (Same as type R) 0.5% Oxidizing & inert atmospheiBS. Avoid reducing atmospheres, metallic vapors. (Same as type R) [Same as type R) ture. Almost any pair of dis* similar metals can be used to makea thermocouple* but some will be more stable and accurate than others. Eight types are documented by NIST (formerly NBS) as standards, but spe- cialized nonstandard ther- mocouples arc available as well, liable 4 lists the eight stan- dard types, which Eire identified by letter codes. The first five (types J. K, X E* and N) are pairs of base-metal alloys. Type K covers the widest range and is most popular. (Handheld DVM- like thermocouple ther* mo meters most often use i>pe K.) T^pe N» the newest* is sim- ilar to K but is more stable at high temperatures and in ox- idizing atmospheres. Type T Js best below freezing and in moist atmospheres, but is very limited at the upper end because one lead is copper lype J includes iron and should not be used in moist or oxidizing environ- ments. It is the best choice for inert or reducing atmospheres* Type E is the most sensitive of the standard thermocouples. +5V Ql MPSA13 (OARUnGTON) looa PLATINUM B2 ^ 1% B3 e2on 5% 2K ZERO R1 lOOK sr. RS 100K I CI ^ BIO " 100K 1% cw C2 0.1 nF R6 1^ R7 soon GAJN m 34.0K 1% + 5V FIG, 6— THIS CIRCUiT INCLUDES 3* WIRE lead compensation, linearizes a pfatinum RTP» and produces a 1 mV C output. TABLE 5— VOLTAGE VS, TEMPERATURE Temperature (C) Type K Chromet vs. Alumel (mV) Type R PH3% Rhodium vs. Platinum (mV) Tungsten vs. Tungsten-26% Rhenium (mV) -270 -200 -100 0 100 200 400 600 800 1000 1200 1372 1400 1600 1768 1800 2000 2200 2315 -6.548 -5.891 -3.553 0 4.095 8,137 16.395 24.902 33,277 4L269 48,828 54.875 0 0.647 1.468 3.407 5,582 7,949 10.503 13.224 15.639 16,035 18.842 21.108 0 0.334 1.037 3-339 6.529 10.296 14.389 18.607 22.213 22792 26,820 30,009 30.592 34.022 36.804 38.556 METAIA METAL B — — .-^-^^^ COPPET^ r t I COPPHR TEMPERATURE DEPEHDEHT MILLIVOLT SOURCE MILLIVOLT READOUT FIG. 7— COLD-JUNCTTON COMPEWSATTON is necessary to offset EMF's generated by the unwanted tJiermocouples at the readout connections. T\pes R, S and B consist of various platinum-rhodium a1* loys, Tfiey are more stable and accurate, and operate to hi^^hcr temperatures. They aJso are less seiTsitive and* of course, more expensive. IVprs R and S are very similar to viwh other. IVpe B flovs a bit iii^lier in lempera- ture. bLit falls o)T drastically in sensitivity below several hun- dred degrees. All three lose sen- sitivity near room temperature. We do not have room here for data on ail thermocouples, but T^t>le 5 gives abbreviated milli- volt versus temperature tables for types K, H. and a nonstan- dard high- tern fJcratLi re tun li- sten alloy thermocouple. (The ealalog from Omega Engineei^ ing. Stamford, CT mentioned last month, contains complete thermocouple reference data.) Thermocouples offer more va- riety in size, shape, and config- uration than any other sensors* Preassembled probes are avail- able in many styles, and wire Is available bare or Insulated with such material as PVC. T(ilon and ceramics. Various diame- ters are available From 14 AWG to 0.0005 inch, atid ribbon ther- mocouples serve for surface temperature measurement. The junction is usually fornied by welding the two wires together, although twisting works for temporaiit' purposes. One-shot measurement of mol- ten steel can be made by simply plunging the two wires into the steel. Wires may be welded to metal surfaces or epoxied In place. One precaution when making surface measurements; place some of the connecting wire along the surface to make sure it does not conduct heat away from the junction. T^vo final notes on wire: First, it can be expensive. Less-expen- sive extension-grade wire is sometimes used in industrial installations to connect remote measurement points to the rt*adout instnnnents. Measure- ment-grade wire is used to make the measurement and runs out to locations at ambient temperature, where it is spliced to extension wire. The exten- sion wire runs the rest of the distance to the readout or con- trol devices. Extension wire matches measurement wire at ambient temperatures, but Is not suitable for high- or low- temperature use* Second, thermocouple cable is often coded by insulation colon Type K. for example, is identified by yellow on the positive wire and red on the negative. An outer brown jacket identifies measurement-grade wire: type K extension wire Is yellow Note that all color-coded thermocouples use red to iden- tify the negative wire, which seems backwards to most of us in electronics. Thermocouple circuit A thermocouple circuit must do three things: amplify milli- volt-level signals* correct for nonlineariiies in the millivolt- versus- temperature table, and provide cold-Junction compen- sation* Accurate amplification of millivolt-level signals re- quires stable, low-drift op- amps. Thermocouples are not as easily linearized as RTDs, but we will not show specific cir- cuits tie re. A wide variety of ana- log techniques have been used, the most common being diode breakpoint circuits. Those cir- cuits use op-amps, diodes, pre* cision resistors, and trimmer potent lometers to create an out- pul versus input ft met ion con- sisting of a series of straight- line segments which approxi* mate the required curv^e. Other approaches use one or several computational ICs (exponen- tial, logarithmic, etc) as part of the linearization circuitry. Today 11 Is common to digitize the am|>liried signal and lin- FtG. 8— THIS CIRCUIT PROVIDES cold-junclfon compensation and amplifies a type-K thermocoyple to 1 mVrC* earize it with a microprocessor On the other hand, since ther- mocouples are approxiniately linear they might not be lin- earized at alL Lets look at cold-junction compensation. Remember that any connection between two unlike mcials generates ther- mocouple voltage. Figure 7 shows that two unwanted ther- mocouples (cold junctions) arc formed where the wires arc con- nected to the readouts copper circuitry (12). As the T2 temper- ature changes, the reading will be affected, even if Tl remains constant. The cold-junction voltage is predictable, however, in fact, its gi temperature coefficient is equal S and opposite to that of the ther- 1 mocouple itself, (If Tl and T2 < arc equal . the net vol tage will be id ZGTO.) It is a fairly simple matter g to use a semiconductor or ther- ^ mistor temperature sensor witli iD circuitry creating an offsetting % millivolt signal. (X Figure 8 shows a complete cir- cult capable of producing a ImV/^C output from a tv'pe-K tliermocouple. It includes cold- 46 junction compensation, but FIG. 9— THIS HANDHELD DEVICE mea- sures temperature using noncontact in- frared, radiation thermometry, does not linearize the ther- mocouple cum^. It would make an ideal circuit to turn your DMM into a thermometer Let's start with the cold junc- tion compensation. An LM335 temperature sensor JC (dis- cussed last month) generates 10 mV/K {273, 15 mV at O^Cl Poten- tiometer R3 adjusts the precise sensitivity of the IC — you can omit It if you use a tight-toler- ance grade LM335. R4 and R5 divide the signed down to 40 puV/ equivalent to type K's sen- sitivity at room temperatures. Without R13 and R14, the gain of 1C2. a modified differen- tial amplifier, would be 1 mcgohm/IOOK, or 10. Resistors R13 and R14 work with R15 and R16 to divide the feedback sig- nal by 2.42:1, which multiplies the closed-loop gain by the same factor. The resulting ^24, 2 gain produces a 1000-mV output from the 4L269-mV (lOOO'C) input signal. The zero offset provided by R6. R7. and R8 is needed because the cold-junc- rion compensation voltage is not zero at O^'C. Note that ICl must be at the same temperature as the ther- mocouple connections. One construction technique is to ep- oxy tlie IC to the terminal block. To calibrate, measure the am* blent temperature, then set R3 for the proper voltage across ICl (10 mV/K, which is 2.732 volts plus O.OIV/^CK Zero and gain calibration is tricky because disconnecting continued on page 83 IXJES YOUR DOC KEEP YOU AWAKE nights yelping at the moon or just about anything real or imagined that moves? Has that riuffy, cuddly pup that you brought home just weeks ago become a four-legged lOO-dB loudspeaker that's endangering neighborhood tranqullit}-? Has Spot frightened the mailman, the paper boy or the Girl Scout on her cookie route? If your an- swer to one or more of those questions Is yes, you should consider building this safe, hu- mane, and efficient radio-fre- quency dog trainer that con- trols nuisance barking without affecting the dog's ability to bark when it's desirable in cases of alarm or intrusion* Developed in cooperation with a major research laborato- ry and tested and approved by veterinarians and animal be- haviorlsts. the Dog TYainer combines advanced BICMOS (bipolar combined with CMOS technology on the same chip) electronic control circuitry with high frequency-vibration gener- ation to teach most dogs to modify their barking behavior within a few weeks. Basic concept Vour handheld RF transmit- ter sends a coded signal that's picked up by a suhcu taneous re- ceiver implanted in the fleshy part of your dogs neck as shown in Fig. L The coded signal trig- gers a microresonator that causes a painless but annoying tickling vibration in your dogs neck, not unlike a flea biting. The tiny resonator grabs your dog's attention and reminds him or her that its time to quit nuisance barking. Figure 2 is a simpliiied block diagram of the complete Dog Tl-ainer, It is not intended to turn a good watch- dog into a passive puppy. For example, you wouldn't want to inhibit your pet s alarm barking when your smoke alarm goes off, your dog is being attacked by the local pit bull or you for- get to put out his bowl of Alpo. Stimulus-response The Dog Trainer demon- strates the beneficial effects of the stimulus*response concept Silence nuisance dog barking safely and i iiumanely witit a wireless remote trainen FIDEL CANINO 47 FIG. 1— ACTUATOR CAPSULE IS LOCATED in Joose fold of dogs skin in a fast, painless impEant operation by a licensed veterinaaan. VOLUMEDOWN- VOLUMg UP- 9^BITC00E ^ Rf OSGtLLATOB RF RECEIVER DECODER MlCROI^ACHirJED POLYSIllCOfJ R£SO?JA!OB LOGIC FIG. 2— BLOCK DIAGRAM OF ELECTRONIC DOG TRAINER SYSTEM showing hand^ held RF transmitter and an implanted actuator first sel forth by the famous Russian physiologist, Ivan Pavlov (1887—19351 He stimu- lated a dog with the sound of a bell for a brief period, and then gave it food and measured the resulting flow of saliva. After a considerable number of pair- ings of bell with food, the sound of the bell alone would call forlh salivalion in somewhat the same manner as had the food; that is to say, the bell had taken the place of the food as stimulus to salivation. Pavlov called this a conditioned reflex, but because later work has sho\TO that many other responses than reflexes alone can be conditioned in a similar manner, the phe- nomenon has come to be known as the conditioned response. F^longed yelping by your dog alerts y^ou to the need for silenc- ing your pet so you press the button on your handheld unit. The irritant provided by the re- motely operated resonator first startles your dog who soon learns to relate the onset of the irritating sensation to his or her nuisance barking. Pretty soon, anticipation of the sensation will take over and your dog learns that, except for a few short alarm barks, silence will avoid the Irritant, In this case the resonator is the stimulus and cessation of nuisance bark* log is the conditioned response* This trainer is an alternative to shock collars » acoustic col- lars, or even vocal-cord surgery as ways to control nuisance barking. It has obvious humane advantages over shock collars and surgery, and not so obvious advantages over high-frequen- cy sound collars- As an alter- native to the sound collar, you don*t need the special collar that is vulnerable to water and you don't have to replace a 9-volt batter>^ in the dogs collar. Because there is no collar you don't have to worrj' about ruin- ing the electronics in the collar if Rex runs out in the rain. Moreover, you can give Rex a bath at any time because the self-contained receiver-actuator is under your dogs skin. Your dog can run through sprinklers or plunge into rivers, lakes or oceans to his hearts content. Micromioiature resonator The trainer includes the lirsl consumer application for a mi- cromachined silicon resonator shown in Fig. 3, Fabricated with manufacturing techniques similar to those used for inte- grated electronics, this "solid- slate*' linear resonator features a pair of folded-beam suspen- sions. The vibrating micro- structure is a transducer that sends signals directly to your dogs nerve endings through an Impedance-matching silicone dome in the miniature implant. In effect, the device is a tiny so- nar emitter. - iVn INCHES — FOIL PATTERN tonne Dog Trainer trans- mitter singie-stded PC board RG. 3— MICHOMACKINED SILICON RESONATOR pravides stimulus to inhibit dog from nuisance barKing. Supporting anchors for folded beam are cutaway. The reso- nator is integrated on a chip with receiver-decoder circuitry. The linear resonator in the Dog lYainer actuator is sus- pended by a pair of folded beams and driven e 1 e c - Irostatically with a comb struc- ture. Vibrationa! motion is in the X direction, while sidewaj^s motion in the y direction is damped by the folded beam* Ttie use of electrostatic forces for actuating microstmciures Is especially attractive because the magnitude of the induced force scales favorably with the small slxe of the actuator, approxi- mately 35 microns wide. The resonator is made by sur- face machining deposited thin films. Botli anisotropic reactive ion etching (RIE) and wet chem- ical etching are used to deiinc deposited films such as poly- silicon (SiO^t* silicon nitride (S13N4). and phosphosilicate glass tPSGK Tb create this free- standing structure, the under- lying superficial layer of SiO^ or PSG is removed by highly selec- tive hydrofluoric acid (HF) etch- ing, after the polysilicon layer is deposited and patterned. The resonator is approximately 10 microns thick. The resonator is an integral part of the microminiature ac- tuator assembly, combining a BICMOS RF receiver and de- POLYSIUCON UTERAL RESOHflTOR RG. 4— ACTUATOR PACKAGE SHOWtNG the tocatJon of the latera! resonator, re- ceiver-decoder chip and top and bottom electrodes that act as anlenna temiinars within the dog. coder on a chip. This clrcuUry Is furnished prepackaged In a minisculc capsule as shown in Fig. 4. The capsule, which mea- sures approximately 50 micro- ns in diameter by 200 microns long. Is Implanted with a hypo- dermic needle. The capsule is located in the hollow needle of a s^Tinge furnished as part of the kit obtainable from the author It is recommended that the im- plantation be performed by a li- censed veterinarian. The kit contains the syringe with the receiver capsule as- sembly the PC board, semicon- ductors, resistors, capacitors, and other parts. The actuator implant In a syringe is available only from the author. Insertion of the actuator Is virtually painless and should take any qualified vet only about 10 sec- onds. You give your vet the di- rections as to recommended location. How does it work? The actuator assembly is en- capsulated with a non-toxic, non-allergen ic material and can remain under your dogs skin indefinitely The tantalum elec- trodes form a conductive bond between your dog's tissue and the internal electronics. The dogs body acting as an anten- na, relays the control signals to the tantalum electrodes. The signal is amplified and sent on to tlie decoder The decoded sig- nal is then fed to the actuator. Each Implanted actuator has its own identification code to pre- vent Interference from say. pass- ing airplanes, garage^door openers* or microwave ovens. Training time can vary depend- ing on your dogs breed and his personality. If a valid data command is present at the implanted re- ceiver within the dog, the reso- nator Is triggered. The choices of switch function available to the operator on the handheld transmitter are: volume up, vol- ume down, on/ofr and mute. The use of these is arbitrary, de- pending on how you want to train your dog. You might want to press mute when company comes over and Rex persists In barking even after you have ex- iled him to the basement. This feature also perm its you to carry on a phone conversation when the door bell or chimes sound or the buzzer goes off on your clothes dryer. Figure 5 is the schematic for the transmitter capable of trig- gering the Dog Ti^iner at dis- tances up to 50 feet. By tying the actuators nine inputs pins to a high, low. or open, the sig- nal may encode or allocate 3x 10^^ or 19,683 different codes. This signal Is then trans- milted serially The on-chip re- PARTS LIST Ail resistors are 1/4-watt, 5%. R1— 10.000 ohms Capacitors. All are 50 volts DC, 10% tolerance , mono or ce- ramic disk unless otherwise In- dicated. CI^.Ol^F 5% 02— 0.1 M^F C3.C4 — 47pF ceramic disc Semiconductors IC1— AF311992 receiver-decoder- resonator 102— API 39 F encoder-transmitter chipEP Q1— 2N2222 NPN tran- sistor Other components LI — 0,05 uH fixed inductor (Induc- trix no.319-02 or equivalent) L2— antenna (hand wound, see text) SW1-4— mmiature SPST-NO mo- mentary pushbutton switch Bt— 9-volt alkaline battery Miscellaneous: PC board, project case (builder's choice), DIP sock- et, battery holder, hardware as re- quired. Note: the followrng items are available from Jack's Elec- tronrcs Emporium, P.O. Box 4079, Farmingdate, NY 11735 • PC board only— 13.50 4 3.50 S&H. • A complete kit of parts in- cluding receiver-decoder- res- onator, PC board, all compo- nents, machined plastic case "-S1992.00 - 3.00 S&H, • An assembled and tested transmitter— S992,00 * S3,00 S&H. Send check or money order. New York residents add 8% sales tax. Allow weeks for deliv- ery* FIG, 5— SCHEMATIC OF REMOTE RF transmitter sends coded signal to im- planted actuator package in dog gp to 50 ieeX away. Jumpers to power bus indi- cate high: those to ground bus indicate low. Coding shown is 111000111. FIG. 6— PARTS PLACEMENT. Mount and solder all components as shown here. Note that jumper locations set code. sistance-capacitance oscillator eliminates the need for crystals lo control frequency The trans- nil Iter circuit can be built in one evening and put to use within hours after thai. If you don't purchase the full kit» start construction by etch- ing and then drilling your PC board. The full size foil pattern Is shown. Use the parts place- ment illustration. Fig. 6. Solder the DIP socket in place first, fol- lowed by IC2, noting pin ar- rangemenL L2 Is a hand-wound antenna. Wrap a 22-gauge insu* lated solid copper wire tightly around a 1/8" drill bit nine times, strip its ends and solder it Hush to the PC board. The remaining components can now be soldered in place. Re- sistor Rl and connector CI con- nect to IC2*s oscillator output pin 14. The resistor-capacitor network precisely controls the frequency transmitted. The identi Heat ion code must be set to match the transmitter to the receiver. IC2's pins, 1 through 7 and 8 and 9 are the input bits controlling your ID code. The number on the label of the shipping bag for the syr- inge is the dala ID code for your specific uniL 111000111 is a sample ID code. This means the first three pins, 1-3, are tied high, with the middle three tied low, and the last three tied high. Don't lose this code. You will need it if you want to build addi- tional transmitters, or order more receiver chips with the same ID. Once you have assembled the transmitter take your dog, and the actuator assembly with di- rections for implanting it to your vet. Wait at least two hours after the Implant operation be- fore you test your circuit. You must allow enough time for the tissue to bond to the electrodes. If the transmitter circuit that you built from a kit does not seem to be working, recheck your work. As with any con* stniction project, cheek for sol- der bridges, swapped wires, and poorly soldered connections. The most likely mistake wiU be improperly placed Jumpers de- termining the code. In the unlikely instance that your silencer transmitter inter- feres with your neighbors TV sets or opens iheir garage doors and they start to complain, re- spond by asking them if they would ralhor have these minor Inconveniences or put up with a noisy dog. You could, of course, demand that they change their garage door codes. Most neigh- bors will understand. You wouldn't want the trans- mitter to fail just as you get an Important phone call or an un- expected visitor. You d be re- duced to having to scream at your poor dog. So keep a spare 9-volt battery within the en- closure just in case. Squelching the unwanted barks of mans best friend has now become safe, humane and easy. With a 50-foot range and the user-friendly handheld re- mote controL we can all sleep better At least we could if it wasn^t April 1st. APR-i RADON. IN YOUR HOME THAT HAS A SIMPLE SOLUTION CaU 1-800-SOS-RADON to get your Radon test information. SEFy\ E!n CoiTKll fiit mm)i>.mmm i m iim mm ! ^ Oj o Your Ticket To SIJCCIDSS Over 28,000 techniciaJ^s havt? gained admit- t^jnce worldwide as certified professionals. Let vouc ticket start opening doors for yoy. ISCET offers Journevrrian certif icaiiOTi in Consumer Electronics, Industrial, Medtcai, Communications, Radar, Computer and Video. For more information, contact the tm^rnationat Society of Certified Electro- nics Technicians, 2708 West Berry Street. Fort Worth, TX 76109; (8171 921-9101. Mame Address _ City, State JSend materiai about ISCET and bei:oming certified- Send one "Study Guide for the Associate Level GET Test/' En ^ dosed is $10 fine, postage^ | Save on cable rental fees! CABLE TV DESCRAMBLERS m'LL BEAT ANY PRICE! JERROLD-TOCOM-ZENITH HAMLIN-OAK-PIONEER SCIENTIFIC ATLANTA •24 HOUR SHIPMENTS! 'MONEY BACK GUARANTEE! ■ QUANTITY DISCOUNTS! MASTER CARD / AMEX / VISA / CCD. 3 Have nnake and model number of equipment used in your area ready CALL TOLL-FREE 1-800-284-8432 CABLE WAREHOUSE 10117 West Oakland Park Blvd., Suite 515, Sunrise, FL 33351 ^ NO FLORIDA SALES ^ CIRCLE 19a m FREE INFORMATION CARD 51 inxELLiGEnT PHonE-LinE moniTOR Let's build Digi-Call and put it in operation. ft! c p DC 52 LAST TIMt: V^T-: DISCUSSED CIRCUIT theory behind Digi-CaJI, ihc au- tomatic digUal telephone call logger Digi Call gives you an au- tomated way of tracking Etit in- coming and outgoing calls. This time, lets bulla the uniL and get it up and nmnlng. Construction The circuit should be as- sembled using a printed-clrcuit board; foil patterns are provided here to make your own. or you can buy the double-sided, etched, drilled, and silk- screened board from the author [see the parts list). Use care in THOMAS E BLACK handling the IC s. and socket all of them, especially the EPROM (IC4), If it becomes necessary to substitute parts, use only ones that you know are exact replace- ments of those listed. In par- tieulan the realtime clock (ICl K an MCH6818A) must be an A" revision device. Also, when se- lecting parts for the telephone interface, note that low-leakage components are neccssar\'. The AC supply must be a wall- trans- lb r me r type that does not \n- clude a ground connection. As we mentioned last month, two different DTMF decoders can be used for IC2, and the PC board supports both. If you look at Fig. 6, you can sec that 1C2 is shown twice in a dashed outline with an asterisk, along with C7, IU5. and XTALl. Otic location is for a 16-pin 7,'3T202 and the other is for a 14 -pin 75T204, Both decoders perform equiv- alenily, so use only one, of whichever is available, and in- stall C7, R15, and XTALl inside the corresponding dashed out- line. Mount all conifmnents as shown in Fig. 6, and check your work carefully, looking for sol- der bridges and open traces* FIG. 6— MOUNT ALL COMPONENTS as shown here. Note that the PC board has two locations for IC2: one for a 16-pin 75T202 and one for a 14-pin 75T204. Use either the 14- or 16-pm IC2 pos'rtion. depending on which chip you use, and install C7, R15> and XTALI inside the corresponding dashed outline. Mount and label LED3 {full). LED4 (on) and S2 (on/standby) on the front panel of your en- closure, and mount Ihe speaker behind a vented grill. Cable connections can be hard-wired or made using head- er connectors (recommended]. The "tip" input (T) of the line interface goes to the red wire of the telephone line cord, and the "ring" input (R) goes to the green wire. Connect the " + ** and leads of the battery connector to a six-cell AA Ni-Cd battery holder. Wire the wall transformer to the "AC" inputs. Last, connect the DB25 con- nector to PI as shown in Table 4. Figure 7 shows the completed prototype. Check*out and power-up Note: If troubleshooting is necessary, you must useAC iso- EPBOM ^ REALT1I« CONFIGURATION CLOCK SWITCH RG, 7— CABLE CONNECTIONS can be hard-wired or made using header connectors. Here's the completed prototype. SP o m o o =1 53 iated test equipment. Line- powered oscilloscopes, DVM's, etc., must be ungrounded. The auUior recommends use of an isolation transformer for safety Failure to do so will cause incor' rect operation of the line inter- face circuit ^ Check all solder coiinecUons for shorts and opens, and all po- larized components for correct orientation before powering up the unlL If any of the following tests do not perform as spec- ified, then you must correct the problem betbre continuing. Disconnect the phone cord if Digl'Call is plui'gcd in. Apply AC power, and push and hold S3 t reset). Verifv that LED3. LED4. and LED5 light up. Re- lease S3 and observe the follow- ing actions during pow^epup: • LED5 (w-dog) is off (inter- rupts off). • LED3 (ruLi.) and LED4 (on) blink for 1-2 seconds (CPU in-- itialization complete). • Four sharp bet Wodi.: FIG, &— OIGI-CALL-S PC-BASED HOST SOFTWARE Is shown here. Activate the menu bar by pressing Esc, use the cursor keys to highltght the destred function, then press Enter to execute \X. On-line help is available for all functions. PARTS LIST All resFstors are y4-watt, 5%, un- [ess otherwise noted R1, R2— 100,000 ohms R3, RIO. R13-^70,000 ohms R4-R6— 22,000 ohms R7, R14— 470 ohms R8— 56,000 ohms R9, Rit R12, R28— 47,000 ohms R15 — 1 megohm R21, R23, R25— 220 ohms R16, R26, R27™not used R1 7— 10.000 ohms HI 8, R29— 1000 ohms R19— 100 ohms R20. R22, R24™1 0,000 ohms R30 — 10 megohms R31^70 ohms, V2 watt Capacitors C1, C2—0.001 ^jlR 100 volts, poly- ester, radial lead C3, C14— 0,01 ^F, 100 volts, poiy- ester radial lead C4, C7, C15-C21, C28, C31, 032— 0,1 ttF, 50 volts, monolithic, radial lead C5, C6, C8-C13, C22, C25, C33— 10 ^jlF, 16 volts, electrolytic, radial lead C23. C24. C27— 27 pR 100 volts, ceramic C26— 5-36 pR variable, top adjust, 5 mm, PCB mount C29— 1000 |xF, 16 volts, electrolytic, axial lead C30— not used Semicoodyctors BRt— D8103, 200 volts, 1 amp, bridge rectifier, DIP package BR2— W005M, 50 volts, 1 amp, bridge rectifier LED1, LED2— Wot used LED3, LED5— LED, red, 1-1^4 LED4— LED, green, 1-1^4 D1-D7— 1N4148 or 1N914 diode D6 — not used 08— 1N4732A, 4.7 volts, 1 watt. Zener diode D9, D10— 1N4001 diode Q1-Q4— 2N2222 transistor ICl— LM324, low-power op-amp IC2— 75T204 (SSI204) or 75T202 (381202) DTMF decoder (see text) IC3--MAX232 or ICL232, 5-volt RS-232 dhver IC4— 27C64-2. 8K CMOS EPROM Use the up and down cursor tieys to select an item, and press Enter to execute it. If you need help on any funetion, highlight ICS— M5M5256A or HM62256LP-t5. 32K x 8 static RAM 1C6— 74HCT373. CMOS 8-bit latch IC7— 74HCT138, CMOS 3-to-8 line decoder ICS— a2C55A, CMOS peripheral interface 1C9--S0C31 or 80C32, CMOS microprocessor IC10— 74HCT14, CMOS hex inverter 1C11— MCl46ei8A, realtime clock with RAM (see text) IC12— LM2940T, 5 volts, 1 amp. low-power regulator Other Components B1— 6 Nl-Cd AA Cells, 400-600 mAH PI— 6-pin, 0.1" header connector SPKRI-^-a-ohms, V/i' 81— 8'position DIP switch 52 — SPST, normally open, mo- mentary. PC board mount 53— SPST, normally open, mo- mentary, panel mount XTAL1— 3.58 MHz, HC-18 XTAL2— 11.0592 MHz, HC-18 XTAL3-^.194 MHz, HC-18 M0V1— ERZ^C07DK201U. 130 volts, 400 amps, ZNR surge suppressor Miscetlarreous: 6-cell AA battery holder, TO-220 heatstnk, wall transformer (8-9 VAC, 30C^1000 mA), PC board, \C sockets, en- closure {8.25 X 6.26 X 2), modu- lar telephone line cord, assembly hard^Aare, software. Note: The tollowing parts are available from Digital Products Company, Attn: Thomas E, Black, 134 Windstar Circle, Fotsom, CA 95630: Complete kit of PC-board and parts with- out enclosure, $169.95; printed circuit board #DC001, $42.50; 75T204 DTMF decoder S14.50, programmed EPROM, $16.50, software on disk (5.25" only), $7.50. All orders add $3,75 S&H. CA residents add CA tax, U,S, funds only, no foreign shipments. Personal and busi- ness checks allow 3--4 weeks. No COD'S or bank cards ac- cepted. Prices subject to change. it and press Fl. To customize DC. EXE to your environment, enter the Config menu and execute each menu item. Be sure to save the changes when vou are done; DC. CFG will be^ updated. You must select the correct COM port and match the baud rate in the configuraUon program to that set on SI. Now connect your PC to Digi- CalL enter the Diags menu and select Test. The Digi-CEitl hard- ware will be tested, and any er- rors will be reported. The expected response is as follows: • Digi^Call 32K Ram : Checks Ok • Digi-Call Clock : Not Set • Digi-Call RTC Ram : Checks Ok • Digi-Cal! Power is : AC Power Return to the main menu ban Enter the DC -Set menu and se- lect Time Entr}^, Use the Set or Auto Time feature to update Digi-Cairs on-board clock. Re- peat the Diags Test feature and verily that the "Not Set*^ mes- sage disappears. Select the Debug Entry in the Diags menu and verify that the displayed time is incrementing and that the date is correct. Variable capacitor C26 allows you to improve the accuracy of the on-board clock. Adjustment should be performed in small increments over a number of days. Monitor the effects of an adjustment by waiting at least 48 hours and checking the re- ported timei readjust the capac- itor if necessary Wliile still viewing the Debug menu, verify that the current status values are as follows (ig- nore the other data entries): • Total Call Count : 0000 • Outgoing Calls : 0000 • Incoming Calls : 0000 • Incoming Hangups : 0000 • Next Rec to Write: 0001 • Last Read Record* : 0000 • Records Remaining: 1557 • Max Record Count : 1557 With the phone line still dis- connected, push Digi-Calls "On" button and verify that LED4 ion) illuminates. Tem- porarily short resistor R4 with a jumper to force the line inter- face circuit into the active state, (Rememben Digi-Call does not fully operate when directly con- nected to your PC.) Now plug Digi^Cairs modular phone cord into a spare telephone jack. c e .9 T3 56 Note: Dlgi-Call will operate only when connecied to standard telephone lines: some systems (electronic keysets and PBXs) are not compatible with Digi- Call. Using a Touch-Tone phone, dial some phone digits and ver- ify that they are echoed in the Dialed Digit entry area of the screen. Rotary (pulse) digits can not be tested in this mode, f^e- move the jumper lead when the test is complete, and exit the De- bug menu. Disconnect the cable to the host PC and remove all lest equipment. Verify that the LED4 blinks when the phone is in use, and lights steadily when TABLE 6— COMMAND LINE OPTIONS /? Display option summary /43 43-line EGA. 50-line VGA mode /B80 Black and white operation (CGA/EGA) /CSO Co\of operation (CGA'EGA) /COMx Communication port, where x = 1-4 CMPx Printer Compress CMD defined by a decimal number /OTOFF DOS error traps off /DTON DOS error trap on /HLPON Help mode on /HLPOFF Help mode off /LPTx Printer port, wiiere x -= 1^ .M80 Monochrome mode {MDA or Hercules) /PGSZx Printer page length, x = decimal number /RBO 80-column printed reports /R132 132-column printed reports /SOFF PC sound off NB Use video BIOS (non-compalible PC's only) it is not. I^ecord several test calls. Digi- Call qualifies phone transac- tions, so be sure that your test calls use actual phone numbers and that the call lasts at least 15 seconds. Also, record some dummy Account Codes after placing or receiving a calL Press asterisk twice, followed by a four-digit code; be sure to enter the code within five seconds. Set Digl-Call to Standby and connect it to your PC's serial port. Transfer the logged phone data to the PC by selecting Data from the menu ban and then selecting Download. After the download completes, you may print the data, save it to a file, or sort it. lb clear the current data set execute the Erase function from the Data menu. Digi-Call is now ready to be placed into service, R-E Buiit ii ymtrsetf , ilf piu/; ii in tmcr BUILD THIS MICROPROCESSOR DEVELOPMENT SYSTEM Build this intenigent 1802 microprocessor development system — for a lot less than the cost of a new Porsche! SURE. HARDWARE IS FUN. BUT ITS sofhvare that makes hardware dance— literaliy. if It happens to be a robot. But designing with micro- processors is difficult. Typically, the first thing you need for a custom design is an operating system, but you can't write an operating system without al- ready ha\1ng one. Of course, mi- croprocessor vendors are more than willing to help; they 11 be more than happy to set you up with a development system for a little less lhan the cost of a new Porsche, If for some reason that's not satisfactoryp read on. Features This project is a stand-alone microprocessor-based control- ler that is suitable for both training and development. It consists of two units. The main unit contains an 1802 micro* processor sockets for as much as 64K of RAM and EPROM, an EPROM burner, serial and par- allel I/O, and a solderless bread- board area. A separate keypad/ display unit, which connects to the main unit via a six-conduc- tor telephone cable, allows you to enter and view programs and data. When your design is com- plete, you can disconnect the keypad/display unit, leaving the computer to pertorm a dedi- cated function. The EPROM-based operating system contains a monitor pro- gram to view and alter memory load and run programs, and in- sert breakpoints ibr debugging, (When an execuling program hits a breakpoint, it stops and returns control to the monitor, at which point you can view and alter the microprocessors inter- nal registers and external mem- ory, and then continue run- ning.) Programs under development can be stored In an EPROM using a software "moi^e'" utility and the built-in EPROM pro- graming capabilities. You acti- vate the EPROM programmer simply by flipping a front-panel switch. Tbgethcn the main and key- pad/display units require about 700 mA of 5-volt DC power. EPROM programming requires a higher voltage (12.5 or 21). de- pending on the type of EPROM used. Partial and complete kits of parts are availabie; a complete system using all new parts can be assembled for less than $200. How it works Figure 1 shows a block di- agram of the circuit, which con- sists of three main sections: the main board, the EPROM board, and the keypad/display board. The main board holds the mi- cro process on decoding logic, RAM and EPROM memory, and the serial and parallel I/O ports. Decoder IC23 divides the 1802's 64K address space into four 16K blocks (IC19-IC22). Another set of decoders (not shown) decode 48 bits of latched inputs (IC2-^IC7) and 48 bits of latched outputs (IC8-IC13). An 8-bit shift register (IC17) provides a clocked serial inter- face to the keypad/display unit, which itself uses latched shift registers to read key presses and display data on the six seven- segment LEDs, The EPROM board works by inserting a 50-ms delay any time the microprocessor at- tempts to write to IC20. If the proper programming voltage (V,ij,l appears at pin 1 of 1C20, the corresponding value will be written to the selected address in the EPROM. Switch S2 deter- mines whether V^^^ or Vpp is ap- plied to the EPROM. The value of Vj,,, will depend on the type of EPROM used, generally either 12.5- or 21 -volts DC, Now let s discuss each section in detail. MMN eOAHQ I CIS IC20 IC2I tC22 00(10'3FTF cs 20 S2 jimjH PROGRAM ■+5V SI T RESET !C?3 DECOOfR XTAL1 S IC1S 1602 CPV At 5 J_L OO 01 D2 m 04 05 06 D7 IC2-IG7»^- FV^RALLEL "-ill OUTPUT L. i4Z BITS) SERIAL r/0 C17 (2 BITS) lCt*lCl3 mflALLEL r IKPUT I-!— (48 BfTSl I- r DO 01 02 D3 D4 05 D6 D7 I I I I 05 D6 TTT OlSPUT iOAflO 555 > TR OUT EFHOM BOARD llLI CO CO 1 1 7 Q 9 A fi 4 5 6 B F2 1 2 3 C F3 B F E 0 H FIG, 1— BLOCK DIAGRAM shows the three major sections of the circurtr the main board, the keypad/dlsplay board, and itie EPROM board. Main board Due to llie size of the sche- matic, the main-board circuit diagram is shown in two parts. Fig. 2. and Fig. 3. The CPU, memory: and associated decod- ing circuitry is shouTi in i'"ig. 2, and the serial and parallel I/O and associated decoding cir- cuitry is shown In Fig. 3. liefer to the appropriate diagram as necessan^ in the descriptions that follow Although the 1802 has a 16- bit address bLis. ii mLiitiplexes them onto eight lines. First the 1 802 places the high-order ad- dress lines (a8~ai5} on the bus. PARTS LIST— MAIN BOARD All resistors are V^^watt^ 5%^ unless otherwise noted R1, R3-RB, Rll, R12— 1000 ohms R2— 150,000 ohms R9— 30,000 ohms RIO— 22 megohms R13-R24— 51,000 ohms, \% wati Capacitors CI — 1 jiR 35 volts, tantalum C2. C3— 20 pF. ceramic C4— 10 |iF, 25 volts, tantalum C5, C&— 0.1 |iF, mini ceramic Semicondyctors IC1*— 74HC238 3'la^ line decoder IC2-IC13— 74HC373 octal D fatch IC14— 74HC13a a-to-e Nne decoder IC15^74HC373 octal D latch IC16^74HCS6 quad 2-input XOFI gate iCl7— 74HC299 8*bit shift register IC18— 1802 microprocessor IC19— 6264 Static RAM IC20— see lestt IC21— see text IC22— 2764 EPROM (with operating sys- tem) 1023—4556 dual i*oM decoder Other components XTAtI— 2.010 MHz crystal P1-P4— wire- wrap pins, 0.025" square x 0,75" J1— 6-conduclor telephone jack PARTS LIST— KEYPAD/DfSPLAY BOARD All resistors are 5%, unless otherwise noted m-n2O-51.000 ohms. H-watl R21-R68— 330 ohms R69 — 100,000 ohms Semi conductors IC1-IC6— 74HC164 e*bit shift register IC7— 74HC00 quad 2-input NAND gate IC8-ICI0— 4021 8-bil shift register Other components DS1-DS3— dual 7-sogment LED display, 0S\ common anode 51-820— SPST normally open, pushbut- ton, PC mount PARTS LIST— EPROM BOARD All resistors are V'<-watt, 5%, unless otherwise noted Rl, R4 — 22 megotims R2— 47,000 Ohms R3— 100,000 ohms Capacitors 01— 0.001 ^F, Mylar C2— 100 pF. ceramic C3-O.001 |iF, Mylar 04— 0.02 |tF, 5%, Mylar C5 — 0.1 p-E ceramic Semiconductors IC1— 74HC02 quad 2-input NOR gate I C 2— 555 timer 01— 1N4148 dtode 01, 02— 2N4124 NPN iransislor Miscellaneous; Chassis & tiardware. power supply, telephone cord & con- nectors, termirial btock. toggle switch, push button switch, solderless bread- boarding connectors. PC boards. Note: The lotlowmg items are available from Page Scientific, 6124 Baldwin St,^ Valley Springs, CA 95252 (209) 772-2076: • Kit including everylhEng but power supply (Model MC-2)— $195 • Surplus power supply (+12, +5, - SKS11 • Operating system in EPROM— S10 • Set of 3 PC boards and manual—^ Please add S5 shipping St handling per order. California residents add applica- tile safes tax. FIG. 2— THE MEMORY DECODING PORTION OF THE CIRCUIT: Note the cfifftmnt connectians to pins 1 and pins 27 of lC19-ICa2. Pins 1 of IC19, !C21 , and IC22 are tied to Vqq, Pin 1 of IC20 (tlie EPROM programming socket) goes to P4, whicft routes it to the EPROM board {Fig. 4) and tfien to prog ramming- voltage selector switch S2. Figure 6 details the wiring. Then, on the trailing edge of TIMING pui.sI':a(ti*aj, IC15 latches those values, and liic 1802 places the low-order bits (ao-a?) on the bus. After a short settling lime, the full IS-bit address bus remains stable for address de- coding. As mentioned earlier 1C23 di- vides the 64 K address space Into four equal chunks. After power-up or reset, the CPU be- gins execution at address 0000. so the lowest address must be filled by EPROM. The other three memorv blocks accept ei- thcr RAM or EPROM. With an arrangenicnt of 16K X 8, the 27128 is ideal for a boot EPROM: the 2764 (BK x 8) will also work. However, if you use a 2764. the upper half of the 16K address space will mirror the lower half. Static RAM ICs are somewhat unusual in that they are avail- able in 8K X 8 and 32K x 8, but not 16K X 8, Address line Aiii of the 1802 selects between the lower and upper 8K slots; ais drives pin 26 of IC19--1C22. Howeven pin 26 of a 6264 static RAM (SK) functions as a chip select (csK Hence a 6264 ap- pears onlv in the upper half of a 16K slot. To achieve a full 16K of RAM at each position, two 8K devices could be piggybacked, except that pin 26 of one should be connected to aTI?, which is available at pin 6 of IC16, The 1802 selects inputs and outputs through 3 lines, no, ni, and N2, For inputs, IC14 de- codes a negative-going pulse at pin 13 for outputs ICl decodes a positive-going pulse at pin 13 (sEL2), Because no-n2 are low under normal circum- stances (i.e., even when no I/O activity is occurring), the selo outputs of ICl and IC14 are not used. Each of the sel2-sel7 out- puts of ICl drives a separate LAix^i i input on 1C2— 1C7. respec- tively. lC14s sEi. outputs drive lC8r^lC13 in like manner The software for writing to an I/O port works as follows. For example, to output parallel data through IC2. the CPU executes the software instruction "OUT 2." The CPU places a binary 2 (010) on the 1/0 select lines No-^N2. The decoder decodes these lines; then riMtrJG ruLSE b m*H> from the CPU generates a pulse on pin 13 of the decoder, which in turn latches data sit- ting on the data bus into !C2, (ti'H is also available through ex- DATA ready' DO D1 0? 03 (M D5 D6 D7 OUT EN DATA RCVD LATCH m D1 02 D3 D4 05 06 07 P3. 12 15 IB 19 DO D1 D2 D3 IC2 ^ 74HC373 05 03 LATCH DO 01 2D 13 14 17 IB R19 51K V&W 11 J3 14 17 18 UTCH DO 01 D2 03 04 05 06 D7 74HC371 EN ool^ Dl 02 D3 D4 05 D6 07 GRO OIHPUT IS IS 1§ SELl NO ICl Nl ^74KC23a H2 ETi TPB 'SEE FOR PINOUT 1016^ V4 74HC86 IC16KJ '/4 74HCSft TPS P2* D7 Jl* R2 1S0K IC16^ V4 f tion, R19 normally holds the latch signal (pin U of ICSlhigh, but that signal is also available at J3, should the external eir- ctiil require data lo be latched al a precise moment. The serial I/O circuit consists of IC17, an 8-bit three-state uni- versal shift regis ten and associ- ated gates. The shift register accepts eight bits of parallel data from the CPU and shifts them out one by one, syn- chronous with the signal that appears at its clk input. Con- versely IC17 also accepts serial data and deliver them to the CPU in parallel, eight bits at a time. The CPU drives the clk input via a special signal called the g output- (After buffering by IC14- d, that signal also appears on J3J Bit 1 of parallel port two (pin 14oflCl) works in conjunc- tion with CLK to control serial 1/ O, That software-controlled I/O allows serial data to be fed in and out of the computer at about 50,000 bits per second. RG. 6— MAKE SUBASSEMBLY INTERCONNECTIONS as shown here. Next time we ll provide details on pinouts of all connectors. lb output serial data, first bring the control line (do from output 21 low, and set g high. Then parallel load the data into IC17 in t^e same manner as a parallel output to the other latches, this time using the soft- ware instruction "OUT L"Then toggle Q eight times, which causes the shift register to clock the data out. To read serial data into the CPU, bring the control line (do from output 2] low then high, thereby latching the data into the external shift registers. This time Q cycles the data from the external shift registers into IC17. The input instruction "IN 9" gates whatevers on the data bus Into the CPU. EPROM board The circuit for the EPROM board appears In Fig, 4. When the cs and mwk signals go low the 555 trigger input drops Lo ground, followed by the output (pin 3). The output remains low for a time period determined by R4 and C4* in this case, 50 ms. That signal pulls the 1802's waTt line low, which efTectively halts ail bus activity for 50 ms. Thus programming an EPROM is really nothing more than writ- ing bytes of data to the corixct memory locations in IC20. (The authors monitor program pro- vides help in burning EPROMs. which is discussed in "Circuit Operation" below.) Keypad/display board The main board outputs se- rial data to six serial-in/parallel- out shift registers (IC1-1C6), one for each digit in the display (see Fig. 5). Each 7-segmenl LED display segment illumi- nates with a low from a shift- register output. This arrange- ment allows the CPU to control each segment independently, thus allowing formation of both numbers and alpha characters. You can even form words » for example, HELLO. On OFF, Er- ror, CHOOSE. HELR Addn An- other advantage of the latched shift registers is that once the display is loaded, it remains In a static condition, hence requires no CPU time. The keypad circuit consists of three parallel- in/serial-out shift registers (IC8-IC101 and 20 in- dependent SPST momentary- contact switches. All 20 key in- puts are tied low through the resistors in the resistor net- works; the four extra ICIO in- puts are tied to V^c- When the user presses a key, a shift- register input goes high. When the software reads the se- rial port. It shifts all three bytes across the data link and into the CPU. The software then elimi- nates contact bounce and mul- tiple key entries. The gates in IC7 steer the o clock to either the keypad or the display circuit, depending on the state of the control input (pin 1 of Jll Softw^are can sense whether or not the keypad is connected. Referring back to Fig. 3. note that R2 holds the serial input high. If the keypad is con- nected, one or more of the key- pad bytes will have a low bit , due to the presence of the pull-down resistors. Interconnections Figure 6 shows how the vari- ous subassemblies, con- nectors, and switches intercon- nect. Switch S2 applies either 4-5- or +V,,p to the pad labeled PI on the EPROM board, which in turn routes that voltage through to pin 1 of IC20 on the main board. The main PC board has four connection areas labeled P1~P4. The -1-5- volt DC power connects to PI: P2 Is an auxiliary con- nector that provides access to several useful signals. P3 is the I/O connector; It contains 128 pins. P3 brings numerous con- trol signals outside of the ctias- sis for access by breadboard clrcuitrs'. Last. P4 is a six-pin 0.1" header that mates with a six pin socket on the EPROM board. Thats all we have space for this time: next time well pro- vide construction details and show how to opt! rate this 1802 development system. In the meantime, if you are interested in building our microprocessor development system, you can begin to gather all the parts. fi-E HARDWARE HACKER Laser printer repairs, sync-separator circuit, GPS navigation update, video interface module, and hacking Super Nintendo! DON LANCASTER We will start out with our usual reminder that this is your column and you can get tots of technical help, off-the- wall networking, plus consultant re- ferrals per the box below. Your best calling times are from S-5 week- days, mountain standard time. But please, before you call, make sure that the answer isn't already in the text or »n the Names and Num- bers or in our occasional special re- source sidebars. And please have a pencil or pen handy. I just cannot believe the number of calls I get from readers that either refuse to look at or can't find the sidebars. I am also greatly expanding our informal PostScript Hardware Hack- tag Consultants Network. Send me d letter or give me a calt if you wish to participate. We also have special Hardware Hacker and Midnight Engineering topics up on CEnie PSRT. You could reach me via [SYNERGETICS] e-mail here to get the preprints, re- prints, tutorials, and other great downloads in our ongoing experi- ment in electronic on-demand pub- lishing — ^and receive late breaking news (especially on PostScript, so- lar energy, and caller ID} literally as it happens. We do ham lots of information this month on the Super Nintendo interface. But first.,, A GPS update We sure had string reader inter- est in our GPS navigation story from two columns back, so here is a quickie update: That GPS. or G/o6a/ Positioning Satellite system includes a ffock of roving satellites that broadcast spread spectrum codes on 1227,6 and t575.2 megahertz. By receiving those signals and digitally prDcess- ing Ihern, you can obtain your exact position and speed anywhere in the worfd to an absolute accuracy of a hundred feet or so, and a potential relative accuracy of an inch or less. Thus GPS can be used for long- distance navigation and for accu- rate surveying. The horse's mouth key paper you need is known as the ICD-GPS-200 document and is obtainable at no charge to U,S. citizens through Space Systems Division/MZEE^ You must send them a letter stating your name and purpose. A great $12 Dan Doberstein re- print titled A GPS Data Receiver \s newly available through DKD Instru- ments. It includes an excellent tu- torial on GPS. full construction details on his ham radio-style GPS receiver, and an extensive bibliogra- phy The receiver is both data-only and an older analog design. While specifically designed with hardware hacking in mind, this receiver is defi- nitely not a "shake the box" project You1l need microwave, digital logic, RF design, and software skills to successfully complete it. Your costs am also likely to be very much higher than by using a modern dig- ital chip set as well. Good navigation technical papers often appear in the Journal of the Institute of Navigation. Those folks also have a new three-volume GPS f^source File available for $50. The prices of the commercial NEED HELP? Phone or write your Hardware Hacker questions directly to: Don Lancaster Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 GPS receivers are literally in free fall, and I'd expect a $35 chip set and a $79.95 system within five years. Today s best offer in a high- quality receiver useful for trucking companies and such appears to be the GPS-1 from Loyola Enterprises. The current list price is $795 plus softwarB. Note that all the GPS signals are right on top of each other and deep- ly buried in background noise* so any old surplus microwave receiver tuned to the GPS frequencies will show you nothing useful at all. Spe- cial digital despreading circuits must get built into your receiver. HI try to work up a tutorial on GPS in a future column. But I think Td better first do some background stuff on the very fundamentals of digital correlation and spread spec- trum communications. Whenever, Video sync separation Another popular helpline topic is video interface. And the number- one ongoing request is for a simple and effective sync separator. The sync separation process lets you take the normal composite video signal and extract those horizontal and vertical synchronizing pulses from it. The most obvious use for a sync separation is to let you cleaHy view video signals on your oscilloscope. Without a field or frame reference, -g all you will see is a blur. Other uses Z for sync separation involve stripping ^ closed captioning or other data off specific horizontal lines present dur- S, ing vertical retrace, grabbing stock ^ quotes, inserting windows, pattern ^ generators, title overlays, wiping 5 and fades, color keying, and other g special effects. Or simply adding a pair of crcjsshairs. Figure 1 shows you a simple and low-cost circuit Tve worked up that 63 can combine both an effective sync separator and a low*cosl universal video interface card. The key chip is the National LM1881 sync sepa- rator mim-dip. You take your usual one to two-volt positive-going sync = ground video signal and ca- pacitor couple it to prn 2. The chip extracts the composite video and produces the active-low TTL/ CMOS'Compatible composite sync output on pin 1, Several other pins on the LMl 881 provide other functions that you may find handy. Pin 3 gives you a vertical sync reference as one sin- gle pulse without the usual teeth or serrations. This is the one you will usually want to lock your scope to. Pin 5 is a burst gate that gives you a slightly delayed horizontal sync pulse that can be used to extract any NTSC chmma burst infomfia- tion from the signal An RC network found on pin 6 is intended to create a default vertical sync in the absence of a true NTSC video input. This is handy for the '^almost" NTSC common to the computers and video games. The NEW FROM DON LANCASTER HARDWARE HACKER STUFF Harcfware Hackor ncprints U or III 24.50 Midnight EngEn&orlng R«prlnlt 16.50 Inc rod lb le Sec rq I Mo n^y Mac h I no 18.50 CMOS CookbooH 24.50 TTL Cookbook 24,50 Acttvo Plltor Cookbook 19.50 Micro Cookbook vol I or II 19.50 Loncoslor CIdssIcs Library 109,50 AppioWntfir Cookbook taso POSTSCRIPT STUFF A$k Tho Guru Roprlnts L II or III 24.50 La&orWrltef Secffits (Ite/Mac/PC) 29.50 PostScript Show A Tell 39,50 Iniro to PostScript VH5 Video 39.50 PoalScript Beginner Stuff 39.50 PostScript Cookbook (Adobe) 16,50 PostScript Ret. Manual II (Adobe) 28.50 PostScrl pi Program Design {Adobe) 22.50 Type I Font Formal (Adobe) t5,50 LaaorWriter Rofofence (Appio) 19^50 Real World Poilf cripl (Rolh) 22.50 PostScript Visual Approach (Smith) 22.50 Thinking In PostScript (Rctd) 22.50 Undst PS Pgrmmg (Holtzgang) 26,50 Tho VVhoFe Works (all PostScript) 349.50 BOOK-ON-DEMAND STUFF Baok*on*demand resource kit 39.50 GEnre PSRT simpter [tltnUdPC] 39.50 FREE VOICE HELPLINE VISA^MC time constant can be shortened for higher scan rates: see Nationals data sheet for details. Finally, pin 7 lets you pick out the odd and even fields of an interlaced NTSC Frame. The output is active LASER RESOURCES Black Lightning RR 1-87 Depot Road Hartland. VT 05048 (800) eLACK99 CtRCLE 301 ON FREE INFORMATION CAltD GEnfe 40t North Washington Street Rockville, MD 20850 (800) 638-9636 QRCLE 302 ON FREE INFORMATION CARD Hewlett-Packard PO Box 10301 Palo Alio, CA 94303 (415) 857-1501 CIRCLE 303 ON FRE£ INFORMATION CARP Lazer Products 12741 East Caley Ave #130 Englewood, CO 80155 (303) 792-5277 CIRCLE 304 ON FREE INFORMATION CARD Recharger 101 Granite St Suite F Corona, CA 91719 (714) 359*8570 CIRCLE 305 ON FREE INFORMATION CARP Don Thompson 23072 Lake Center Dr #100 El Toro, CA 92630 <800) 457-5776 CIRCLE 306 ON FREE INFORMATION CARD only when the input composite vid- eo has a full interlace. Advanced color editing is one possible use. An external source of the usual five -volts DC is needed. Since the current is only seven milliamperes, just about any old supply will do. As usual, keep the power bypass ca- pacitors real close to your chips. Several other features on the cir- cuit are handy for special video in- terface cables. The three large capacitors let you couple red. blue, or green video off ennitter-foiiower outputs and then connect them to RGB monitors. A 75-ohm resistor is handy for terminating cables. And a logical high signal is useful for such things as enabling the sound on cer- tain receiver/monitors. By itself, the inverter is handy for converting aclive-iow sync into ac- tive-high and vice versa. While most of the video systems use active-low sync. Commodore and one or two of the others might not. The printed circuit layout is shown in Fig. 2, Empty boards* kits, tested circuits, and both stock and custom interface cables are available from Redmond Cable. You can call or write them for a current price list. I'll also post this layout on CEnie PSRT so you can easily create your own accurate version without the need for any photographic work. See HACKFG51PS. You might want to keep some empty or partially populated boards on hand to solve special cabling and interface uses. The large runaround FIG. 1— THIS COMBINATION SYNC STRIPPER and universal video interface can solve a lot of problems for you, including Syper-Ntnlendo-to-anytning interfacing, video overlay, and scope TV frame locking. Kits, fully tested units, and custom cable assemblies are available througtr Redmond Cable. SYNERGETICS Box 809-BE Thatcher, AZ 85552 (602) 428-4073 ground on the outside of the board is especially handy for shiefded-ca- ble terminations. For this month s contesl, just tell me about an unusual or off-the-wali use for a sync-stripper circuit. There wilt be all of those usual Incredible Secret Money Machine II book prizes, along with an all expense paid (FOB Thatcher, AZ) tinaja quest for two going to the very best of atl As usual, send your written entries directly to me al Synergetics, rather than over to Radio-Electronics editorial Let's hear from you. Nintendo interface As Fig. 3 shows us. there's a very interesting MulthOut connector on the back of those Super Nintendo game machines. That gives you lots of alternate video and sound output formats that you might find handy For instance, you can go to a RGB monitor for sharper images and better colors. Or add total ster- eo sound or Super VHS improved resolution. Or you may want to hang any old TV-compatible color monitor plus a pair of headphones on the machine to silence kids and keep them off your main prime-lime television set. Let us see exactly what is on the connector and how to use it. By a special arrangement with Redmond Cable, all the connectors, that inter- face kit. and special and stock cable solutions for most any Super Nin- tendo interface are now available. The Mufti-out connector is really SEx-over-six edge traces on a double sided circuit board. Looking at the rear, the traces are odd numbered 1.3,5.7,9,11 on the top, going right to left. And the similar pins ane even numbered 2.4.6,8J0,12 on the bot- tom, again going from right to left. Both pins 7 and 8 are grounds. The parr make terminating several shielded wires much easier. A + 5-volt DC output is provided on pin 10. It appears to be capable of driving at least 50 milliamperes. But you shouldn't suck the poor ma- chine dry. and you should very care- fully bypass and filler any use of the supply There are a pair of sound outputs. Pin 1 1 is your choice of monophonic sound or L-R matrixed stereo. Note that "left" plus ■"right" equals *^both." Pin 12 is L-R matrixed stereo. These signals are capacitor- coupled and are the pnDper size for your usual audio inputs on a hi-fi receiver or computer monitor. Note that some computer monitors have a sound capability and some do not. The easiest way to tell is to find an obvious volume control located somewhere on the set. No volume control no sound. Other monitors may need a special pin activated to tum the sound on or off. We'll see an example of this shortly All your sound cables should, of course, be shielded. Sadly the power levels are far too low to usefully drive a speaker or a pair of headphones. But Radio Shack has an interesting beastie that no Hardware Hacker should be without. It »s their #227-1008C mini-amplifier and speaker The L+R output easily drives the mini- amp via a miniature phone plug. The mini-amp solves the problem of a monitor that has no sound. You can also plug headphones into your mini-amp for any silent running. The mini-amp is powered by your choice of an internal alkaline 9-voll battery or by a plug-in 9-volt DC supply Because of the matnx used, you cannot get stereo directly off pins 1 1 and 12. Instead, you have to add the two signals together to get the left channel, and subtract the two sig- nals from each other to pick up the right channel. Like so.., CL + R) + CL-R) = 2L and (L + R)-CL-R) = 2R A stereo dematrix can be done with a quad op-amp or a transformer and four resistors. In theory, you could make use of a CMOS- biased inverter amplifier but your common - mode supply noise rejection might suffer on the nght channel. Mone details on biased inverter amplifiers appear in my CMOS Cookbook. Let me know if you need any more information on stereo matrix extraction. There are three different types of video outputs found on the multi-out connector Plain old gn^unded sync composite video appears on pin 9. That can be routed to any standard NTSC video input on a monitor, VCR, or television set. Note that a direct video input will often have sharper images and better cobrs than does entry by way of some channel 3 or 4 modulator That s be- cause less electronics get in the way and an RF modulation and de- modulation can be eliminated. " UNIVERSAL SYNC I VIDEO INTERf ACE RG. 2— PRENTED CIRCUIT BOARD LAYOUT and overlay for the universal video inter- face. Accurate and camera-ready art is also avaltabre vra GEoie PSRT as file HACKFG51.PS. PostScrtpl downloads can eliminate all darkroom work. SUPER VHS "V The luminance channel (or Super VHS video appears on this Jine One voH p^ak lo peBK into a 750 load. InlernaSEy capacitor coupled, I 9 I NTSC VIDEO | — PlaLn old NTSC composite video appears on this lirte. The sync itps are at gro;jnd. One volt peak to peak into a 7S£1 \ob6. Internariy capadtor coupled. on L+R SOUND The monophontc and stereo malrixed sum sound appears on this pin. One vol! peak is suitable tor amplfBers but not headphones. 12 L-R SOUND The stereo matfixed difference signal appears on this pin. Add pins 1 1 and 12 for Sefi stereo; subtraci ihem (or right stereo output signals. 10 + 5 VOLTS DC A limited amount of +5 voits supply power may be drawn out of this pit) for sync Inverters or doing a stereo dematrixing. Limit current to 50 milltamperes and use thorough bypassing. SUPER VHS "C" GROUND A pair of ground pins is provided lo ease terminating of shielded video and audio | cables. /RGB SYNC For linear RGB monitor use. | Active low combined vertical ; and horizontal sync pulses. ; 0 to 5 veil high logic source is*^ CMOS and TTL compaiabJe. RED VIDEO GREEN VIDEO - ( 4 I BLUE VIDEO For linear RGB monitor use. One vott peak -to -peak off of an emitter foltower source. Requires a series 200 coupNng capacitor. GROUND The chroma channeJ for Super VHS video appears on th\$ line. One volt peak to peak into a 75il loacj. Internally capacitor coupled. For Jlriear RGB monitor use. i One vott peak-to-peak off of | an emitter follower source. ! Requires a series 200 pfd j coupling capacitor. For linear RGB rraonitor use. ] One voll oeak-to-peak off of t an em it ler (o I lows r sou rce j Requires a series 200 ^fd coupling capacitor. :? A pair of ground p?ns is provided to ease terminating of shielded video and audio cables. FIG, 3— THE SUPER NINTENDO MULTI-OUT REAR CONNECTOR has all sorts of useful Video and audio options available. Here are the key delaits. Super VHS. orY-C video appears on pins 7 and 8 v^/ith Ifiat luminance ■"Y" output on pin 7 and the chromi- nance or '*C" output on pin 8, Ttiey can be routed to any system which accepts Y-C video. Because of the separation of the color information and the higher bandwidths. these outputs should look far better than regular composite video. The best video of all, though, is available as a separate red Con pin 1). green Cpin 2). and biue Cpin 4) video. The red, blue, and green out- puts come from emitter followers and have a strong DC bias. They musf be capacitor coupled lo your ultimate destination using a 220-mi- crafarad or higher series capacitor on each line. Be certain to put the C + ) side of the capacitor on the Nintendo end. The needed RGB sync appears on a fourth active-low line on pin 3. The active-low sync is correct for Apple IIGS. Sony, and most "stan- dard" RGB uses. It is the comple- ment of what IS needed for Commodore and certain others. The line swings rail*lo*rail or ground to + 5 and thus is both CfVlOS and TTL-compatible. Note that some connector pfugs do not have all of their pins available, especially for the RGB sync and VHS chroma. The Redmond plugs include all of the pins. Several interface circuits appear in Fig. 4. In each case, a partially populated Fig. 1 circuit can be used to greatly simplify your cables and interface. In Fig. you can connect RGB video to any Apple lIGS monitor by using the three serial video capaci- tors and the right connector on each end of your cable. Since the lIGS monitor has no speaker, you have to use a hi-fi or the Radio Shack mini-amp. Figure 4-5 shows an interface to the older Sony KV13t1^CR re- ceiver/monitor Again, we have those three serial video capacitors. This time we use an enabling re- sistor to turn on the internal sound and eliminate any need for a com- panion amplifier The interface to the Commodom 1084 color monitor is shown in Fig. 4-c, As usual, the rBd, blue, and green video have to be capacitor coupled to the appropriate pins on the LfoRGS connector. This lime, an active-high sync is needed rather than active-low, so the inverter must get added as shown. While the sound is internal it has to be routed via a separate audro cable and pho- no plug that goes into the Audio input. The size and position adjust- ments on the back might also need a slight readjustment. Yes, we are working on VGA and multi-sync solutions. Stay tuned or check CEnie PSRT for availability Once again, some mix-and- match kits, all-pin connectors, parts* and cables are available from Redmond Cable. Do let me know which other interface circuits you would like to see worked out. Laser printer repair Where can you go to get training, parts, and information on today's laser printers? Many of the printer manufacturers ane super secretive and go far out of their way to prevent you from getting the parts and ma- terials you need to make best use your printer and to keep it alive cheaply. So, for this month's re- source sidebar, I thought we'd gather together some of the best of the laser repair resources. FIG. 4— TYPICAL SUPER NINTENDO TO LINEAR RGB video monitor interface connec- tions can give you sharper resolution and betler colors. The overwhelming majority of all laser printers use Canon engines, so that is usually where you'll want to start, Hewlett Packard has by far the best and the most available Canon manuals in the industry. And since an SX engine is an SX engine, those HP manuals are most useful on similar Apple. QMS, and lesser machines. Figure 5 summarizes the key HP service manuals, along with some of the competing machines they cover HP recently has sharply raised all of their service manual prices. Many of these HP service manuals are in the $100 range. Even at that price, they pay for them- selves on their first use. They are essential gottahaves. HP also sells parts to anybody overnight via VISA and an 800 order line. Again, sadly, individual parts are hard to get. They prefer to sell you an entire S50 fan instead of the 50-cent grommet which is the only thing that ever goes wrong with the fan. The best place to go if you want to buy individual lasepprinter parts is Be an FCC LICENSED ELECTRONIC TECHNICIAN! No costly school. No commuting to class. The Original Home-Study course prepares you for tlie "FCC Commercial Radio- telephone License" This valuable license is your professioival "ticket" to thousands of exciting johs in CommunicaUons, Radio- TV, Microwave. Maritime, Radar, Avionics and mo re... even start your own busincssl You don't need a college degree to qualify, but you do need an FCC License, No Need to Quit Your Job or Go To School This proven course is easy, fast and low cost! GUARANTEED PASS-You get your FCC License or money refunded. Send for FREE facts now. MAIL COUPON TODAY! commfliiD VRoYucTlbrfs" " 1 FCC LlCE^fSE TRAINING, Dept. 90 ■ RQ. Box 2824, San Francisco, CA 94126 j P lea se rush FREE delai Is i mmedl ate ly ! . ADD HESS, C(T¥ .J ^ — — ' CIRCLE 10a ON FREE INFORMATION CARD 67 NAMES AND NUMBERS Aham Tor 27901 Front StfBet Temecula, CA 92390 (714) 676-4151 CrRCLE 307 ON FREE INFORMATION CARD AIS Satellite 106 North 7th Street Perkasie. PA 18944 (215) 453-1400 CIRCLE 3QB ON FREE INFORMATION CARD Benchmarq 2611 Westgrove SlelOl Carrollton, TX 75006 (214) 407-0011 CIRCLE 309 ON FREE INFORMATION CARD CADalyst 859 WJIIamette Street Eugene. OR 97440 (503) 343-1200 CIRCLE 31D ON FREE INFORMATION CARD Caplugs 2150 Elmwood Avenue Buffalo, NY 14207 (716) 876-9855 CIRCLE 31 T ON FREE INFORMATION CARD DKD Instruments 1406 Parkhurst Sima Valley, CA 93065 (805) 581-5771 CIRCLE 312 ON FREE INFORMATION CARD Electronic Product Review 41 1 Eagleview Blvd Exion, PA 19341 (215) 458-6440 CIRCLE 313 ON FREE INFORMATION CARD GEnie 401 North Washington Street Rockville, MD 20850 (800) 638'9636 CIRCLE 314 ON FREE INFORMATION CARD Institute of Navigation 1026 16th St NW, S!e104 Washington, DC 10036 (202) 783-4121 CIRCLE 315 ON FREE INFORMATION CARD Loyola Enterprises 904 Meadowburm Court Virginia Beach, VA 23452 (804) 459-2972 CIRCLE 316 ON FREE INFORMATION CARD Redmond Cable 1737VA1 NE 67th Court Redmond, WA 98052 (206) 882-2009 CIRCLE 317 ON FREE INFORMATION CARD Rutland 16700 E Gale Avenue City of IndustryXA 91745 (818) 961*7111 CIRCLE 318 ON FREE INFORMATION CARD Sengraph 760 Indiana Avenue West Bend. W! 53095 (414) 335-7200 aRCLE 319 ON FREE INFORMATION CARD SGS/Thompson 1000 East Bell Road Phoenix, A2 85022 (602) 867-6259 CIRCLE 320 ON FREE INFORMATION CARD SkyviSLon 1010 N Frontier Drive Fergus Falls, MN 56537 (800) 543-3025 CIRCLE 321 ON FREE INFORMATION CARD Small Parts PO Box 4650 Miami Lakes, FL 33014 (305) 557-8222 CIRCLE 322 ON FREE INFORMATION CARD Space Systems Division/MZEE LA AirForce Base, PO Box 92960 Los Angeles. CA 90009 (310) 363-0215 CIRCLE 323 ON FREE JNFORMATlON CARD Synergetics Box 809 Thatcher AZ 85552 (602) 428-4073 CIRCLE 3a4 ON FREE INFORMATION CARD Don Thompson, who also now of- fers by far the finest multi-level train- ing and repair seminars in the entire industry. My two favorite places for toner refilling supplies and materials are Arlin Shepard of Lazer Products, and Walt Jeffries and his cnew at Black Lightning. The latter are also into special toners for fabric printing and printed circuits as well, should you have such a need. Black Lightning also publishes The Flash, a free and friendly news- letter crammed full of useful desk* top information. There are several laser-printing and toner-recharging trade journals, but the only one of any con- sequence is Recharger They are already up to several hundred pages per issue, and tist dozens of sup- pliers for just about any laser-print- ing repair need. I try to carry a lot of toner and laser printer repair stuff on our continued on page 75 HP MANUAL HP PRINTER APPLE PRINTER QMS PRINTER 02686-90920 LaserJet 1 LaserWriter PSBOO (CX Engine) LaserWriter Plus 33449-90906 (SX Engine) LaserJet II LaserJet ill LaserWhter NT LaserWriter NTX LaserWriter F LaserV/riter G PSS10 a Turbo PS820 a Turbo PS815-MR PS825-MR 33459-90906 (SX Engine) LaserJet 110 LaserJet HID 33471-90904 (LX Engine) LaserJet HP Personaf LW NT PS410 1 33491-90929 (SI Engine) LaserJet Nisi FIG. 5— THESE HEWLETT-PACKARD LASER SERVICE MANUALS can be used for mechanical repairs on most ol the printers shown here. While expensive, they are the best Information sources available, and Far easier to get than Ihe others. Many drf- fofent laser printers use Canon engines, so these HP manuals are very useful on similar machines. HP also sells parts to anybody overnight via VISA and an SOO order line, although individual parts are hard to get. 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RADIO-ELECTRONICS. 500- B Bi-County Blvd., Farmingdale. NY 11735, FAX: 516-293-3315 REMOTE CONTROL A-B SWITCH— lets you hook up your cable box by remote control, when needed, then unhook it just as easily! Restores TV, VCR features. Oc replace any A-B switch with this superb quality remote version. Bright LED indicators. JUST S35. INCLUDES SHIPPING. Visa. MC. Of check, (C.O-D. S5 extra) Fast delrvery. 30 day money back. STAR CIRCUITS. RO. Box 94917, Las Vegas, Nevada 89193 1-800-535-7827. TWO TRANSMITTERS IN ONE! 5 MINUTE ASSEMBLY! MONEYBACK GUARANTEE! New Law Enforcement grade device on a single chip is the most sensitive, powerful, stable room transmitter you can buy. Uses any 3V-12V battery. Or attach to telephone line to monitor all telephone conversations over 1 mile away without batteries! lOOmW output! 80-130MHZ. Receive on any FM radio or wideband scanner VT-75 microtransmitter, S49.95 + 1,S0 S&H. VISA. MC, MO. COD's add $4.00. DECO INDUSTRIES, Box 607, Bedford Hills. NY 10507. 1-800-759-5553, CIRCLE 127 ON FREE INFORMATION CARD AUDIO UPDATE Hear today, gone tomorrovw. LARRY KLEIN NO new prescripUon drug reaches the market without extensive double-blind test studies designed specifically to eliminate the influence of the "placebo effect." In a nutshell the testing works something like this: a group of\ say, 50 sufferers from some specific malady are chosen to participate tn the study They are divided into two groups, each matched as closely as possible in terms of relevant characteristics such as overall heafth, severity of the malady under study mental at- titude, etc. An important part of the design of any research study is the isolation and elimination of irrele- vant random factors that may skew the results in one direction or an- other Unfortunately, the history of science is littered with studies that were invalidated by methodological flaws. Every person in the two matched groups is given the same treatment, be it injections, pills, diathermy, or whatever, except that those in group B gel a phony treatment. They are unaware that the "thera- peutic" injection is a saline solution, the pills are sugar tablets, and so forth. Group A is grven the real drug being tested under identical condh tions. To prevent unwitting clues being given by the doctors involved, those administering the drugs do ^ not know which drug is which. This :: is the essence of the "double-blind" ^ technique. g' One might imagine that from that E point on all that is needed is a I checkup to see who gets better and ~ who doesn*t. However, things are 6 not that simple. Lets suppose that a 30% of those getting the real drug improve. Would that be considered a reasonably successful outcome? Not if 30% percent of those getting 70 the placebo (phony drug) also get better. And that is exactly what hap* pens repeatedly in medical re- search. In many cases, the administration of any treatment whatsoever — including a chanting witch doctor — will produce a certain number of cures or at least some alleviation of symptoms. In less sophisticated times than ours it was a common belief that faith could work miracles: now most people prefer to refer knowingly to mind/body interactions for an ex- planation. There are those who be- lieve that if a belief system — however irrational— can effect a cure, then why not go along with it? (More on this later in respect to the alleged special sound qualities of super-expensive audio equipment). Trustworthy ears All of the above is a preface to my discussion of a paper given by Tom Nousaine at the Audio Engineering Society convention last October. Tom's paper, Can You Trust Your Ears Cpneprint 3177 L3}. deals with a matter that I ve pondered for many years. In past columns Tve dis- cussed the various problems of subjective testing, and I've touched on the question of why those lis* teners obsessed with high-end au- dio equipment lend to hear things that objectively don*t exist. Audiophiles frequently complain that critics such as myself are too insensitive to respond to the sonic nuances in question, or that we have vested interests in not hearing the virtues of very expensive equip- ment. But aside from anyone's al- leged hearing deficits or personal perversity, it is very easy to demon- strate that audiophiles — and others — do indeed tend to hear things that have no objective exis- tence. All that needs to be done is to estabiish a listening panel of au- diophiles and general listeners, as Tom Nousaine did. He set up a placebo companson between an amplifier fed directly from a CD play- er (A) and the same amp with a supposed "signal processor" in the signal path CB). Despite the fact that the listening panel was exposed to exactly the same material in both A and B, a preference was expressed for A or B 76% of the timel Of course, the audiophiles in the group strongly preferred A because they had been told that there was an ex- penmental signal processor in chan- nel B. As Tve remarked before, many audiophiles feel that their credibility is on the line during every listening experience. Because of the implicit audiophile belief that every compo- nent inherently sounds different, you can see how detecting such dif- ferences is very important. But there s more to the story than au- diophile ego trips. In further testing without the "signal processor/" when preference between identical amplifiers was still 76%. there was no difference in the scores between audiophiles and general man-on- the-stfeet consumers! It appears that under certain con- ditions, even unbiased ears tend to hear differences when none exist. Perhaps — and this is sheer specula- tion — any interruption in the input signal causes a shift in the listener s auditory zero-reference level, which is then interpreted as a change in musical quality, ft s been known for years (1 first wrote about it in the early 70"s) that the ear hears minor differences in level Cless than 0.5 dB) as dif- ferences in clanty. In Ns paper Tom attempted to quantify the effect. When slight loudness differences were introduced, listeners much preferred the louder alternative. For unknown masons, the effect was even more pronounced when the louder choice was presented to the fistener second. Critics* recommendations \ ve detected the appearance of a pernicious philosophy among a few audio writers. Although they nnay acknowledge that there is no objec- tive evidence supporting their pref- erence for a given product, the fact that they have a preference is suffi- cient justification for a recommen- dation. The problem with that sort of approach is its ultimate unfefiability. Tve had friends who compulsively traded m fine top-of- the- line equip- ment for newer, more recently touted products in the hope of com- ing one step closer to audio nirvana. And in truth they did bask in ''unsur- passed sonics with superb imag- ing/" as one reviewer put it. until the same revieweKs) soon discovered an even juicier cherry-of-the-month to extoi. In the same way that double-blind placebo testing is needed to dif- ferentiate drugs that work from those that don't, equivalent tech- niques are needed to separate the genuine advances in the audio art from those that are merely commer- cially inspired or delusional Toms data indicate that those audio critics who evaluate equipment primarily by uncontrolled listening tests (sup- ported or unsupported by measure- ments) are likely to be fooling themselves and their readers. Dou- ble^btind testing is the only way to ensure audio objectivity. Tom concludes his paper with a plea for further research in listening test techniques. I couldn't agree more. For most of audio history, comparative listening tests were mostly what audiophiles did for fun on Saturday afternoons. To my knowledge, the first serious rndus- try listening tests wene undertaken by the FCC in deciding on a stereo FM broadcasting system. Today, with the proliferation of signal- compression techniques used in broadcasting and data compression used in digital home formats, refin- ing the methodology of listening- test evaluations becomes a high- priority concern in professional audio. R-E EQUIPMENT REPORTS continued from page 7f gives you the op! ton of showing a suggested layout on a breadboard, instead of the schematic view. This latest version of Global Spe- cialties Protolab has several im- provements over earlier versions, namely improved graphics (EGA is required) and the additional mod- ules that present transistor and di- ode circuits. The manuals that are supplied cover only the operation of the software, without providing any Circuit theory— an unfortunate change from previous versions. Our suggestions for improvements? We would like to see a little more con- sistency in the menus from module to module. And we'd like to see the removal of copy protection. Protolab system software costs $129.95. Additional modules cost $19.95, We'd recommend it to any- one trying to learn the basics of cir- cuits. R-E Try the bulletin board system (RE-BBS) 516-293-2283 The more you use it Ihe more itsefuf it becomes. We support 1200 and 2400 baud Qperaliofi. Parameters: 8K1 (S data bits, no parity. 1 stop bit) or 7E1 (7 data bits, even parity, 1 slop bit). Add VQijfself to our user tiles to increase your access. Communicate with ottier R-l readers. Leave your comments on R-E with the SYSOR RE-BBS 516-293-2283 LEARN i to , CWSN/ MaIISTTAINI/ RffAIR CAMCORDERS MOUSER ELECTRONICS Sales & Sfockmg Locations Nationwide DRCt^ 117 ON FREE INfORMATtOW CAnO HUGE EXPANDING MARKET! ills tuxU ft^tiJiitiiHTit iiH \ tntt (Ht^ tr Hit HI t .nih iw(k*i^ in tt^i' - ( Kit i ntiUkm Uti u> im*MtUM its l«»«IE ^iltHH'! II .1 Lti t ilvir iFit- i^tvf ttuftvin fffff iNfOHAiATioN PACKAGE calf or Write: Toli-Free 1-800-537-0589 Viejo Publications, Inc. 4470'1{>7 Sunset Blvd. #&00 Los Angeles, CA 90027, Depl. REC CmCLi 133 ON FREE INFORMATION CARD DRAWING BOARD Let's work on the vertical section of our scope. ROBERT GRDSSBLATT Si I 8 C P LU 6 ■6 m 72 IVe been doing thrs column for a long time and* after writing more words than i can count (even with my shoes off). I can tell you that the most important ingredient is the feedback I get from those of you who take the time to dnDp me a note. The reason that I'm mention- ing this is that I seem to have re- cently overstepped the lines of electronic propriety When we were recently talking about automotive charging systems I made the comment that gener- ators were a "really stupid charging system/" and the amount of output power you could get from them was solely a function of how Fast the engine was turning. A lot of you took me to task on this and I'm therefore formally apologizing for what, in retrospect, was somewhat of an overstatement. Generators were used for a lot of years in a lot of cars, and it wasn't really fair for me to condemn the whole thing out of hand. Generator- based charging sys- tems had their faults (especially at low engine speeds and during heavy current demands), but alternators have their quirks as well. Since we were talking about a regulator for alternators, I spent most of the time discussing alternators and summed up generators in a fev^ (unfortunate) words. And while the theory of oper- ation behind mechanical voltage regulators is really similar to the electronic ones, it's still true that they had to deal with large amounts of current. The modern alternator/ regulator arrangement has the ad- vantage of low-current control of the output of the alternator I got a lot of thoughtful letters on the subject and, whtfe I don't have the space to thank everyone who wrote. I want to give a special tip of the hat to David Ramsh, Lucius Day. and William Newell. Even though they beat me up as well, their letters were great to read and forced me to review stuff I hadn't thought about jh^^ATy By 7>f^>*w FIG. 1— HERE ARE THE DIFFERENT SECTIONS of the scope mat we have to desigo. Since college. I screw up as often as anybody, and I'm grateful for people like those three guys who can catch the goofs and call me on it in an intelligently written letter that s a real pleasure for me to read. Once again, my sincere thanks to all of you. But back to the subject at hand. We*ve got the horizontal section of our scope up and mnning. and its time to turn to the vertical circuitry. As with the horizontal section we just finished, the vertical section is really made up of several different sections, each of which does a dif- ferent job. Figure 1 gives you an idea of the pieces we have to design to get the scope working. Even though we*re designing a scope that can look at botfi digital and analog input signals^ the fact that we have an LED display means that any signal we measure has to be "digitized" ultimately before it can be seen on the scope. That isn't to say that weVe building a digital scope — we're not. I just want to point out that having a display made up of discrete points means that all the input signals have to be reduced to discrete values. With a CRT- based scope, you can display any analog value — with a digital display like ours, we have to quantify the input signal to match the restric- tions of the display. The work of digitizing the input signal is done in the 'Vertical Drtv- er" section in Fig, 1. The standard way of doing that is to stack up a bunch of comparators and config- ure them so that each successive comparator goes high as the input voltage increases. Even though the basic idea is really simple, from a practical point of view it's alv^ys been a real pain in the neck to trans- late it mto neality. Because you want the voltage steps to be as accurate as possible, you have to spend a lot of time working out the values of the resistors used in the voltage-divider chain that makes up the analog-to- digital conversion circuit. The way anDund the problem is to use the LM3914 dot/bar display driver from National Semiconduc* tor; the pinout diagram is shown in Fig. 2. The 3914 is basically an ana* _7 s_ *7 (po p/ V PS 0S ^F£j?£^ca oar P7 ^^^j£?^£MZe ADi/US r QS DoT/SA^ MOPSL Fia 2— THE LM3914 OOT BAR DiSPLAY driver will be used to drive our scope display. LKARIV Vi IK CLEANING/MAINTENANCE/REPAIR EARN UP TO S1000 A WEEK.WORKING PART TIME FROM YOUR OWN HOME! bg IC. and that means you have to do some work to calculate the val- ues of the components needed to make the chip do its thing. There's an internal ten-step voltage divider to drive the chip's comparators, but external components have to be used to set the overall voltage range for the whole chip. That's important for us to talk about since we want to be able to switch ranges when we're using the scope. National Semiconductor has made the job of determining the 3914 s voltage range as easy as possible by making the two ends of the IC s comparator chain available on pin 4 (the low end) and pin 6 (the high endX The ten comparators rn the 3914 each have one leg chained to a resistive ladder so that the com- parators respond linearly to the in- put voltage. If the external compo- nents are set to have the 39T4 cover a one-voft range, each tenth-of-a- volt increase in the input voltage will cause the next 3914 output, in turn, to become active. Just as with any comparator cir- cuit, getting the component values worked out to have the 3914 re- spond to a particular voltage range is a tncky business. The details are spelled out in the data sheet for the chip but. for our application it s bet- ten faster, and much easier to han- dle the problem by padding the level of the input signal before it gets to the 3914 input. Even though we'll do that, tt's still necessary to know ex- actly what the 3914 is telling us when it turns on a particular output. In other words, while we don't have to configure the 3914 to cover dif- ferent voltage ranges, we still have to know what range it is covering so we know how to pad the input. The absolute voltage generated by the 3914's internal voltage reg- ulator is 1 .2 volts and, if you set the 3914 up as shown in Fig, 2, each increase of 0.12 volts at the input will cause the next 3914 output, in turn, to become active. You should notice that the lower end of the di- vider chain, pin 4, is connected to ground so that the 3914 wilt cover the range of 0-1.2 volts full-scale. Once you have it wired up, you can fool anDund with the reference-ad- just terminals and the internal re- sistor chain to change the full-scale -2] 07 0^ 59/^ FIG. 3— CONNECT LED^S to tho 3914 as showrt here to serve as temporary in- dicators, response of the chip. 1 don't want to go into it here since well be prescal- ing the input voltage, but you can get the details for doing it from the data sheet. The 3914 can be set to output either a bar-type Call LED's on) or a movtng-dot Conly one LED on) dis- play. For our purposes, a single dot is preferable so we 'II be leaving pin 9 unconnected. When we expand the display to twenty LEDs, we'll be using two 391 4 'sand the mode-con- trol pins will have to be handled dif- ferently—but we'll get to that later, It may seem to be somewhat wimpy to operate the 3914 in such a minimal mode by not taking advan- tage of some of the obviously slick things it can do. Using the internal voltage reference in its most basic fashion, and only sticking with a moving dot is configuring the 3914 in a really bare-bones way. But don't forget that the reason we're using this chip in the first place is because it's a one-chip answer to driving the LEDs in our display. And even though we have it set up for a 0-1 .2 volt range, we'll be putting circuitry in front of the 391 4 's input to pad the input voltage to have switch-selec- contfnued on page 82 THE MONEY MAKING OPPORTUNITV OFTHE 1990'S IF vou art able to v.ork with common small hand tools, and ate Miliar wjtti bs^ic eiearon»cs (i e. able IQ U5« a vtrttmeter. undersiana DC electronics) . (F you possess a^^rage mechanical ability, and have a VCR on Vihtch to pracltce anil learn tnen we can leach YOU^CR mainteftance and reparr^ FACT: up to 90% of All VCR maltuftctjons are due lo Simole MECHAIitCAL or ElECTRQ PAEGHANrCAL ijreitdowns» FACT: over 77 mifiron VCRs m use today naiiOflwKJe! 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This nuvvly- rtn ist'd edit ion contains hundreds of proven^ te&tetl circuiLs— hand- drawn by Forresl — using today's mosl popular linear* TTL and CMOS ICS, Forrest gives you full diiln for each device and circuit — pin niunbers. logic tables, supply voltages, and signal waveforms — so you can quickly dupltcato each circuil- There*s also practical in* formation on construction meth- ods, troubleshooting, and inter- focing different IC farm lies. If you work with ICs you gotta get this bookl fiarls c/edJE?ts. Or t^tdttt ttitvct fmm iiifthTetii! Add S3 ihiitjting (S4 fn Gatiada, rlifiH ht>r^}r CA ptmur ttdd mlt^ ttix. i i HighTcxfc 7 lis ^firanur Road Suitr ISL Saa Dina.Cl^ 92] 21 73 AMPLIFIER continued from p^ii^r 36 rent of about 60 mA. Repeat the same procedure for the righl channel, adjusting R16R. Check the voltage at the two speaker output terminals. The DC value should be less lhan 50 mV, If all is well so fan replace Fl and F2 with 2-amp fuses, con- nect a pair of test speakers to the output leads, and apply an input signaL If everything still checks out, feed the wires through the end plate using a plastic strain relief to secure the wires. Now install the final fuse values, slide the cover in place, and attach the other end plate, lostallatioii and use The first thing you intisl do is decide on an appropriate loca- tion for the amplifien Good choices include under a seat or in the trunk. Once the unit is mounted, wire the power, ground, and speakers. Ground can be picked up from the chas- sis of the vehicle, if desired, making sure it is a solid ground. Use appropriately heaw wires for the main power and ground, as they will have to conduct as much as 40 or 50 amps. You may wish to pick up the main power close to the battery, in which case you should use a f useable link as the very first piece of the connection, Fusea- ble links are readily available from most automotive parts stores. You may also wish to in- stall an engine noise filler in se- ries with the main supply. The l2-volt control lead is ide* ally connected to the radio's electric antenna output, if it is so equipped. If not available, a separate switch can be used. Fi- nally* wire the inputs with shielded cable. Its best if the car radio you Ye usi ng has a volume* controlled line-level output, which most of the better radios have. In any case, do not drive the amplifier from tbe speaker output of the radio — the signal levels could damage the ampli- fier inputs, and the signal would include the inherent dis- tortion of the radios amplifier. One last word of caution: the heatslnk is designed for the peak'io-average power ratio of music. Therefore, for applica- tions which require continuous output at the rated power levels, forced cooling or a bigger heat- sink are recommended. Happy listening! r1&«B m*\t (hps a I 1 1 S>f« mi. 1 1 >^ •1^4 V3M« CIRCLE 1&0 ON FREE IMFOftUATlON CARP Need Information about Businesses? Call the Business INFOUNE! There are over 9 million businesiies in the U.S. — and finding information about them can be virtually impo^iKible, especially when you need h fast. But now there*s a way... a nevolutionar>' new ser^'ice called Business INFO UN EI Need to know the address and phone number for *'XYZ Company" somewhere in Rorida. or the name and phone number of a "Cadillac Dealer" in Palm Beach? 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If not lAtL^fied, [ may return the booliJ» within 10 div s and have my memhcriJiip cancel lal. I agree to pur- chase 1 or rm^re boots at regular Oub Prices during the next 2 ycafs, and ma> resign any lime thereafter. A shipping/handling charge aiKl sales tajt will be added to all order* Name Address City State . . Phone. V S. OHTTncj Tin* onltT n^bfKt to aeccptiocc by Ac tEfiC 7S COMPUTER CONNECTIONS Will you OS/2 it? JEFF HQLTZMAN Cut to April. 1987. IBM and Microsoft jointiy release a new operating system, the heir apparent to DOS. OS/2 ver sion 1.0 was tuned to the 80286 microprocessor, but it had limited DOS compatibility, and it lacked sig- nificant support from applications deveiopers. Fast forward to June. 1990. After five years and three major versions. Microsoft releases Windows 3,0. It supports all Intel processor modes, has excellent DOS compatibility, and significant applications sup- port. It quickly catalyzes a stagnant industry. Fast forward to Spring, 1992. After five years and as many ver- sions. IBM will release OS/2 2.0. It s aimed at the 386 and higher, offers excellent DOS (surely) and Windows (maybe) compatibility, but still lacks significant support for native applications. It also intro- duces a new desktop shell with a whofe new paradigm for the user interface. And under the covers, it reportedly makes extensive use of object-oriented technology of the sort that has allowed Borland, for example, to make rapid gains on Lotus and MicfDSoft in recent years. Power users and true-blue loy- alists may eat it up But what about the rest of the world? Further, does ^ OS/2 offer significant power that g> we both need and can't get S elsewhere? Does it package this ^ power in an accessible manner? g Can IBM overcome the stigma (or I just plain indifference) that has ^ haunted OS/2 almost since its in- i5 ception? Can IBM market this prod- ^ uct to a comnnunity of users, the g vas t m ajori ty of which, acc ordi ng to recent studies, are still not even run- ning Windows? Can it succeed in an increasingly Windows world'? Can it 80 coexist? And what about Windows NT, the only product with which comparison can fairly be made? What is OS/2 2.0? Circle one: Its IBM's 32-btt pre- emptive protected operating sys- tem for tntet pnocessors. Its IBM's attempt to apply everything it has teamed about building powerful, re- liable system software during the past thirty years lo desktop PC s. It's IBM s attempt to provide a plat- form for integrating diverse hard- ware platforms and operating systems. It's IBM s attempt to wrest control of the PC industry from Bill Gates. It's just another graphical en- vironment for developing and run- ning software. All of the above. Some of the above. None of the above. However you answer the ques- tion, IBM's oft-repeated intent with OS/2 is to provide a better DOS than DOS and a better Windows than Windows. It's safe to say that Big Blue has succeeded with the DOS part of the equation. It's too soon to tell about Windows- I'm writing this just after the first of the year based on beta release FIG. 1— BETA VERSION OF OS 2 2,0 runs tough DOS apprications flawlessly, and has improved compatibility wtlh Win* dows. More important in the long run is that this is the first widespread object- oriented operating system for desktop PCs. F6.167 of OS/2; specific features and operations may and probabfy will change by the time the product is released commercially Commer- cial release is presently scheduled around the time you read this, but that may change as well — only time will tell. DOS vs. Windows DOS programs will run either full screen or in a window (i.e., in a bit- mapped graphic screen that sinnu- lates normal text mode); with or without EMS. XMS. and DPMI memory; and with a fine degree of control over how your apps run. Compatibility is extremely good. For example. I ran LapLink 3.00a in its parallel turbo mode to transfer mul- tiple megabytes of files from an- other machine in a windowed DOS session, while simultaneously run- ning other native -mode COS/2 spe- cific) software. The mouse had trouble keeping up. but all files transferred flawlessly. All DOS ap- plications I tested worked fine, al- though some timing-dependent programs acted funny Forexample» a Pacman game ran incredibly slow. Lotus 2.01 ran fine in a win- dow, including displ^ of graphs. In general, running on comparable hardware. DOS apps have a snap- pier feei under OS/2 2.0 than under Windows 3.0. Conclusion; DOS compatibility is not perfect, but it it s probably good enough for most ap- plications. Windows programs run, but slow- ly, and not in a window, and not with Windows -OS/2 clipboard support. In other words, you cannot cut and paste between Windows and OS/2 programs, nor can you simulta- neously view Windows and OS/2 programs. IBM promises to remedy these problems in the final release of the product. Select- do One highly anlicip3ted aspect of OS/2 2.0 is the Wod^place Shell (WPS). WPS provides the first widespread object -oriented user in- terface for personal computers. The overall look of WPS is quite similar to that of Windows, but operation is much different. Everything on the desktop (including the desktop it- selO is an object. You manipulate objects with the mouse. Unlike Win- dows. WPS is a two-button system: You use the left button to select objects and the right button to do something to or with them. CYou can customize mouse button usage and many other system features quite easily For example, you can bring up the color palette editor, select a desired color, drag it over the desk* top and dn3p it. Voifa — instant color therapy!) To move an icon, select it Cleft button) and then move the mouse with the right button held down. (A shortcut is to just drag with the right button,) To copy an iconn select it and drag as before, but hold down the Ctrl key before releasing the right button. To open an icon (ex- ecute a program, open a folder), double click with the left button. You can also create a shadow (sometimes called a reflection) of any object by holding down Ctrl + Shift when completing a right- button drag. Rumor has it that a shadow will function in an object- oriented way i.e., a shadow would "inherit" all characteristics of the shadowed object, including any changes made to the original, but changing the shadow would not af- fect the original. However, the cur rent release appears only to support UNIX-like symbolic links, in which changes to any one instance of an object affect all other instances of it. Copy, move* open, shadow: Those are direct manipulation oper- ations. Objects in OS/2 also sup- port indirect manipulation: just single-click the right button on the object, so a menu pops up. The con- tent of the menu varies, depending on the type of object, but you 11 usu- ally see operations like Help, Open, Copy, Delete. Move. Print* Find* etc, (Direct manipulation operations appear on the menu so that you can, for example, copy a file using a di- alog box to specify the destination,) You can drag an object to a Shred- der icon to delete it. and to the Printer icon to print it. (The shell in Windows 3.1 reportedly will have similar drag-and-drop features but we'll have to wait and see.) Under Windows you can double- click an icon repeatedly to launch multiple instances of a program. In OS/2 s object-oriented paradigm, that doesn't work. The icon and the running application amount to dif- ferent views of the same object. To get multiple instances of a program running, you must create copies of the icon and launch each desired program instance from a different icon. An OS/2 window resembles a Windows' window, but there are dif- ferences. The biggest difference is that you cannot minimize a window. When you click the minimize button, a second icon is not created. In Win- dows, you double click on an icon in the Program Manager to execute a program. When you minimize the program* a new icon is created on the desktop You use the new icon to restore the program, terminate it, etc. By contrast, in the WPS* no new icon is created. Again, the idea is that the icon and the window are simply different views of the same object. In Windows" PM, it's easy to spot an active program either by its Window or its icon. WPS does it differently. Icons with active pro- grams have special cnDss-hatching. In both Windows and WPS, you can obtain a list of currently active pro- grams by pressing Ctri + Esc. You can also get a list of active programs in Windows by doubfe-c lie king on the background, and you can get a list of open objects in WPS by click- ing both of the mouse buttons on the background. Menus and scroll bars have a trendy 3D appearance. Text in a win- dow scrolls as you operate the ele- vator bar The system includes an extensive hypertext help facility, al- though the beta lacked much infor- mation. In addition, there is a slew of mini applications (calculator, note- pad, alarms, charting, telecom- munications, icon and text editors, bit map print/view/convert, etc.) and games (including solitaire, tetris clone, etc.). Advanced features OS/2 comes with a boot man- ager that by itself can make it worth purchasing the operating system. In exchange for giving up one mega- byte of disk space, you get the abil- ity to boot any operating system from any of four primary partitions. You can also break a primary parti- tion down into an extended partition with one or more logical drives, each of which can have its own bootable operating system. You can boot any partition or drive automat- ically, or choose from a menu each time you boot. On my test system, 1 have three bootable partitions (DOS 3.30, DOS 5.0, OS/2 HPFS) and two more for stonng data. From within OS/2, you can boot a DOS session from a floppy disk. It can be any version of DOS, and it can include device drivers. Even more, you can create a boot image of that floppy disk, store it on your hard disk, and boot from the image whenever desired. In the beta, de- vice driver support was limited, and the procedure for creating the boot image was totally buried in the on- line documentation. IBM also includes a programming language called REXX, which is like a cross between BASIC and a thatch pnogramming language. The on-line help facility extensively documents REXX, including examples: another help file lists all OS/2 commands. A special Master Index will index all help files on disk and allow you to access them, complete with hyper- text links. Reading a specific help file gives you search and print ca- pabilities, but the Master Index does not. Then there's the resource re- quirement. OS/2 requires a 386 or better, runs adequately in 8MB of RAM, and requires 30MB of disk space just for the operating system. Those are significant barriers for many users — but th^'re no more significant than the resources re- quired by Windows. As of this writ- ing, OS/2 won't work with SCSI devices, and it supports only IBM video standards (i.e.. no SuperVGA or coprocessor cards). Weighing in For a new opereting-system prod* uct to succeed, it needs strong backward compatibility (DOS), compatibility with today s hot ticket (Windows), and a compelling path to the future OS/2 may be the ulti- mate platform for running DOS ap- plications, but that is slrictfy a short- term benefit, Windows compatibility might turn out to be problematic. "Better Win- dows than Windows" implies being able to do everything Windows does at least as well as it does it, and some things better Currently. Windows apps run slowly, not in windows, and the clipboard is not supported. Assuming those basic problems are solved, there's sttll the matter of dynamic data exchange CDDE). object linking and embed- ding COLD, and multimedia exten- sions. IBM seems doomed to playing a catch-up game with Micro* soft as vanous areas in Windows are enhanced. In any case, total re- liability is a must. As for the future. IBM is poten- tially in excellent shape. Deafs with Next and Apple over the past f©w years, as well as Borland and other language vendors, potentially give JBM a tremendous edge over Micro- soft, whose chief allies (DEC and Compaq) have never been known for strategic softv^ne innovation. Can OS/2 succeed? Yes. if its very, very good. Would I buy it? I might, if it delivers on its promises or finds a way to make me not care about transgressions. Should you buy it? Depends. Eventually you will own OS/2 or the functional equiv- alent, regardless who makes or sells it. The fact is that the brave new multimedia world of the future cannot be supported by DOS. Right now multimedia seems like an add- on to an already adequate way of doing things. Some day. though, historians will look back on this era as one of sensory deprivation, akin to the black and white years of com- mercial TV. OS/2 or something like it is the software engine we need to get there. Regardless who wins, it will certainly be fun getting theie. Stay tuned. R-E start, Makiif Wave •jf '3 II ; !!!!!■■ Switch to B-hK precision for the right function generator at the right price. Don't let tight budgets keep you from the function generator performance you need. B+K PRECISION has ifie industry's most complete line of cost- effective generators.. .from 160 KHz to 13 MHz ^ All are rugged lab ^ grade instruments that witl perform as promised, every time. Here are just two examples. 13 MHz Universal Function Generator with Frequency Counter ■ 0.1 Hz to 13 MHz output ■ Sine, square, triangle, ramp, pulse, triggered* gated burst TIL outputs ■ Two built-in generators can be used independently or together for AM or FM ■ 1000:1 sweep range ■ Variable symmetry for unlimited waveforms I BuilMn 30 MHz frequency counter 2 MHz Function Generator ■ 0.2 Hz to 2 MHz ■ Sine, square, trrangia ramp and TTL or CMOS output ■ Four* digit frequency display B \^riable DC offset ■ Variable symmetry Model 3011B Mode. 3040 ^IjlSS^'O ^259^^ For more information on the complete line of B K PRECISION function generators or for Immediate delivery, contact your local distributor or B-f K PRECISION, Domestic and Jnternatior^l SaJes 6470 W. Cortland St.. Chicago, IL 60635 312-8S9'1448 • FAX:312-794'9740 DRAWING BOARD continued from page 73 table full-scale readings of any range we want. Get the chip working and connect LED s as shown in Frg. 3 to serve as temporary indicators. Since the chip win be working over a 1.2-voll range, you can use a signal gener- ator as a source for the chips tnput. If you don't have one, any line-level audio output will work just as well. When we get together next month we'll expand the driver to handle twenty LED's and design the rest of the vertical circuit. That will make the scope operational and we'll be able to talk about all those bells and whistles. And th^'re the best part. b-e [nt^rMifinal This brochure can be worth a lifetime of memories. Btctjming a host funnily in the OPEN DOOK Student Kxthanjlc program can be one (jf the most rcwanlinjj decisions you'll ever maitu. TKis is a unique opportunity to learn personally about other cultures, make life-long friendships around Ihe worid. and bn>aden the homons of stu- dents. famiUcs and schools here and abroad, A few short months can enrich a lifetime. Only you can open the doot Call: SOO-afifiOPEN (6736). ^j^r:^;^ or write: I^HCT^ PftJtsc send mc a firce Hi>.st Family brochure, Name:^ _^ Address: City: .Stati- ,Zlp:_ Phone: L OPEN 250FultortSlrEet DOOR m.Box7} STUDENT Hefiip$iead.NYIlSSt EXCHANGE CIRCLE 77 ON FREE INFORMATION CARD R-E Engineering Admart Rales: Ads are 7}/axTA\ One insertion S995 each, Sii insertions $t50 each. Twefve insertions $925 each. Closing dale same as regular rate card. Send order witti remillance to Engineering Admart. Radio-Electronics Magazine. 500-8 Bi-Ccunty Blvd., famimgdale. NY 11735. Direct teleptione inquiries to Arline Rshman. area cod&-1-516-293-3D00, FAX 1-516-293*3115. Only W% Engineering ads are accepted fQr this Admari. Mm) MIDI PROJECTS BP1g2— MIDI rnterfacing enables any so equipped instrumems. regardless ol the man- ufaclurer, to be easily connected mgelher and used as a system wiMi easy computer control of these music systems. Combine a computer and some MIDI instruments and you can have what is virtually a prog rammable orchestra . To order your copy send S6,95 plus 52.50 for shipping in the U .S to Electronic Technology Today Int.. RO. Boi24g, Massapequa Park, MY 11762-Q240. DR. "CHIP " MUNK SAYS ^"^L,TY SERVICE AFFORd^AEIUTY **Chi|>'" experts jxgm mth Dr, Munk. TKCrs PC based niicroct>niroHer dtvcl- c^pmcnt tools urc the mmx cost elTcclive tor vetcraiis or licfiixincrs, m\i»{ vm »i*TOT3Js. vmm 6Ba&bl«KTtf S&lLl virjk ilPBHiliKl^ .mm 6}I|U"rtt5 UlE[CS03 |>KOCiHAVl%irk.S FROM SJWS.W t n^iri OK PC BANi-n mx svvtrAis rai»M wwjw CALL TOLL FREE l-K0O-336-«321 The Eneineers CoJIaborative, Inc, Rt #3 Iktx 8C, Itarion, VI' 05822 USA TKLHK02t525-345K FAX:^S02|52S*.^S1 CIRCLE 189 ON FI1EE INFORMATION CARD FCC LICENSE PREPARATION Tho FCC has revised and updated the oomrr^ordal license o)iam. The NEW EXAM covers updated marine and aviation rules and regu1tt»ons, transistor and digitaJ dfcultry. THE GENERAL RADIOTELEPHONE OPERATOR LICENSE - STUDY GUIDE contains vital^nfOfmat^on. VIDEO SEMINAf^ KrrS ARE NOW AVAJLABLE, WPT PUBLICATIONS 7015 N.E. 61st Ave. Vancouvier. WA 98661 Phone (206) 750-9933 DepL 50 CIRCLE 177 ON FREE INFORMATION CARD TEMPERATURE continued from page 46 the thermocoupie changes Uie net cold-junction voltage. With the input shorted {0 mV), set R7 for an output equal to room temperature: for example* 25 mV at 25X (77"Fl Connect 41.269 mV to the input and set R14 for 100 mV plus the room temperature (1025 mV at 25°C]. Resistor RTs small bias cur- rent has no effect on normal op- eration, but causes the output to go high if the thermocouple breaks or bums out, Noncontaet thermometry We've finished our study of temperature sensors, but let s close with a quick look at non- contact infrared radiation ther- mometry. Figure 9 shows a handheld device and Fig. 10 illustrates its principle. Any object warmer than abso- lute zero radiates energy. Both RG. 10— ANY OBJECT WARMER than absolute ^erp radiates energy. The radiated energy is focusod on a temperature sensor. the intensity and the spectral distribution of that radiation increase with temperature* (We re alt familiar with "red hot" and "wiiite hot" temperatures, but even "cold" objects radiate energy.) According to the Stefan-Boltzmann law the radi- ated energy densitj' is propor- tional lo T^, where T is absolute temperature. It is that law which allows scientists to deter- mine the temperature of the sun's surface. In Fig. 10 the radiated energy is focused on a temperature sensor Designs vaiy. but in gen- eral the sensor should be small and ha\T a low mass for good response time. Some designs insulate the sensor by placing it in a vacuum. The lens material might need to be specially chosen to pass long-wavelength infrared, especially for low-tern - peralure measurement. Some designs might not use a lens at alK substituting a focusing mir- ror instead. A red or infrared iil- ter might be added to minimize interference from ambient light. The Stefan-Boltzmann law applies perfectly only to "black- body" radiators. In reality, the ability of surfaces to radiate en- ergy varies. Every surface has a reflectivity and an emissivity, A perfectly reflective surface has a continued on page 92 I 1 J3 9 (Tl 83 BUYER'S MART FOR SALE Si s c B t3 a XI B4 TUBES: "oWesi," 'taiest.' Paris and schematics. SASE tor Nsts. STEINMETZ 7519 Mapfewood Ave., RE.. Hammorxl. IN 46324 RESTRICTED technical ir^formaHon: Electronic surveil lance, schemaiics. locksmiihing, covert sciences, hackrng, eic Huge ftelecUon. Free brochures. MENTOR-Z. Drartrer 1549. AstStiry F^,NJ 07712. CABLE TV co^tveners: Jerroid, Oak, Saenlifsc Atlantic. Zennh A many G&iers "New MTS" SlerOO add-on: mute & volume Ideal to^ 400 and 450 ownars! \ (aoqi a2&762a. Amex. Visa. M C ceptod. BAB mc,, 4030 Beau-D^Bue Oiive, Eagan. MM 5S122- TUBES, ne* up to 90^* ott, SASE. 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OH 43207, 80C52-Basic microcontroner hoard Baste mi&r- peeler 32K RAMh 16K Eprom.Eprom progfammof. RS232, expansion connocior. Bare board wilh manuaf^ sd^cma!>cs S22 95 80C52- Basic mcfO- processof cr^p S25 95 Assembted and lested $124.95 PROLOOJC DESIGNS, PO Bot 19026. Ballimore, MD 21204, OSCILLOSCOPE SO MHz. Hewlett-Packard, sol- id stale calibrated, manual S29O.00 1 (800) a35-a335 X-159. CABLE TV Equipment. Most type availal^le. Special: Oak M35B S39 95. No catalog. COD or- ders onJy, 1 (BOO) 822-9955, OUR monthly picture flyer fists quality surplus parls al low prices. Serd today for vours. STAR- TRONlCSt Box 6B3, McMinnvilte, OR 9712B. PHOTOPftCT folders urider #1400 SS.OO. QUiers S7 00. PosipaJd LOEB, 414 Chestnut Lane, East Meadow, NV 11554. (5t6| 481-4380. CLASSIFIED AD ORDER FORM lb rtsi yaw own ctssftjlisd Kl put on* tto^ Radro-Electronics Classified Ads, 500-B Bi^Courtty Boulevard, Farmingdale. NY H735 PLEASE I N DEC ATE in which caiegory of Classified advising you wsh your ad to appear. For - v: ngs. there is a surcharge of $25.00. ( j P ar.s KjIs ( ) Btisiness OMOftumites ( ) For Sale ( ) Edijcation, Instruction ( ) mnied ( ) Satellite TeleviSfOO ( ) . ^ Special Caiegory: S2S.00 PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS. fNo refunds or ciedils for typesetting orro/s can be made unless you deafly print or lype your copy.) Rates indkaied am fof standard style dassilied ads only. See below for acfcfilional ctiarges for special ads. 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Joineco 80386SX MoHierboard * Eits> ™EcAiiitd iS S'xl J'} ' Zero Pf one wijf openiion * Supponi up irt 16MB of RAiM * Infd S03H7SX/Lcimptib^e rruih tupmcessor socket * AMI BIOS 16-bit J rid tihO B-bii ^ip-jftsbn bus ikits JB3616SN , $299*95 Conner IDE Hard Drives TTiis %cr]Ci itf hiph-|>erft>fniJtncc Conner dbk diivti ii dt^ipicd forUi^ storage cjpj(it)% CP3000 40WH 3.V Profile $249*95 CP3O0S4 mms ^.S^lo^ Pfordc„»,.S399.95 CP50104 XHmiV Low Pmfik.**S479.95 CP32a4 200MH S.y HH ,„S699.95 ADP20 1 6-bif \ \m^ Adapter S29.95 Fujitsu 101 -Key Enhanced Keyboard Thti U>Kkj:d TdtUicl 12 KujCtiun Im. wp4rj[c cufvrir jnd r.Ejm^ri ■ IBM K7XT/AT jnd ctKnpjttiyc compuic rv • Automjticilly TOi^diev btn^tm XT or AT • LE1> fndiuiiirt for Num l^^k Cap lj)ck, and St rail Lock • I'actik Fcrdhatk • Mjftiul intludcd * Onc-^f jr Wamnrv Many more Upp^itdt Products FKB4700..„, , , »»J79.95 Toshiba 1.44MB 3.5 Internal Floppy Disk Drive • IBM PC/XT/A rjiidaimpitiblei • Compaiibic w-iih DOS ^TftMom 3.3 or highrr • include* dll n«tr4wr>' insulUiion hardw^rr • 1 .4 4MB formatted hijih dcfivih- mode • ^20KB ronmiittl W' dcnutv cnode • Sur. I % -rW % \r D Uctitd dmr ^) • Onr-jtJi Minufjaurtr'v ^'jrrant)' 356KU $99.95 Integrated Circuits* EaOuCijb^ LS 111* 74LS00 »™ S-25 S. 1 5 74LS02 „_a5 AS 74im^ *25 -15 74LS08„..^„. 29 -19 74LSN.*.*- 39 .29 74LS30. 25 ,15 74LS32 — .25 .15 74L574 29 .19 74LS76. 39 ,29 74LS86. 25 .15 74LS112„- 35 ,25 74LS123 39 .29 74LS13H 39 .29 74LS175 39 .29 74LS193 59 .49 74LS244„,, .m .59 74LS245.».. M .59 74LS373.... .........69 39 74LS374, 69 .59 Linear ICs* ^mEsL lilt TL082CP ™..$39 S,49 LM317T..«« 65 .55 LM324N .35 .29 LM336Z,. .,*L05 .95 LM339N 39 35 NE555V ..««.29 .25 LM556N 49 39 L.M723CN .49 39 lAr-*lCN .29 .25 I.Ml iSHN H .29 LM14H8N , *5 39 LM1489N .45 .39 ULN2005A .............. .69 .59 m3914N,. 95 1.75 NE5532 J. 19 1.09 7805T 45 .41 7S12T. 45 *41 * Ciili fur a atmpletf tistiug oftCs Miento^f Part No. Function siiooor 10 4>10DOA9A.EO 2H^KDlr 1 20111— $1.79 2^KDIP tSOro L69 t MB DIP 80n 5.99 t MB Dip IWJns SA'9 .nf'KSIPP Ii]0m«-.18.95 :^,K>ISt.M «nni 20-95 iXfBSIPP «(lm««.59.95 1MB SIMM KOm ....64.95 Miscellaneous Components* Potentiometers \3\\m ivjiLdilc fiium ohim intn ^pKC mjfkcd 50011. IK. SK. lOK, WK. iWK. iMEC I 43PXX 3/4Wau.l5Tyrii..... S.99 1 63PXJC 1/2 Wati, \ Turn 89 TransistofS And Diodes PN2222 $.12 IN751 S-15 PN2907 .12 C106BI .65 1N4004 .10 2N4401 -15 2N2222A .25 IN4148 .07 IN4735 .25 2N3055 .69 2N3904 32 IN270 .25 Switches JMTI23 SP|>i;On.On(lo^) 51.15 206-8 SPST. 1 6-Fin Ki^m 1 .09 MPCI21 SPOT. MS 102 J»PST. Mf»mmiJtn {iWi- Billion J*. 39 Connectors UttcrlptioB Price D615P Male, 25- pin $.65 DB25S Fcmak. 2 5* pin .75 DB25H HihmI 39 DB25MH .Mctjl Hood 1.35 LEDs XC209R $.14 XC556G Tl 3M. (Green) .16 XC556R T\ 3/4. (Red) .12 XC556Y ri 3/4.(Ye!lnvv) .16 IC Sockets 8LP $.10 8WW $.49 14LP .n 14WW .69 )6LP .12 16WW J9 24C.P J9 24WW 1.15 28LP .22 28WW 1.39 40LP .28 40WW 1.89 C;i!l or Write for a FREE 90-Page 1992 Catalog! 24- Hour Toil -Free Order Horline: 1 •800*831-4242 $30.00 Mmimum Order Mention MaHKcy 2 JAM ECO O^JTBOIW: COMPONENTS COMPUTER PRODUCTS 1355 Sharcway Road Belmont, CA 94002 FAXi 1 •800*237-6948 FAX: 1 •41 5*592 2503(t-, BBS Support: 415-637-9025 [nter national Sales • Customer Servicer • Technical Ambiance • Credit Dcp.iftfnciit * All Otlief loquiria! 4 15-592-8097 • 7A.Vf - 5PM P^T. O 1992 famm 4/9^ Ttmn Prioo ujAatea m mtkmi iwocc- C\ RciiJcmv Atld "..J'S"^, 7.7S%^ oi 8.5% Sjln Jm licinrn uibject iviibbiltt)- ind ptm ukr Shipping, lundting and km picte 1 in icrnu/ wsrrajnic^ ti jv^iljbl c ittju Tine* are ^ddiiiu ml uintfi rtqueti ► m CIRCLE 114 QH FRE£ IN FORMAT] OtJ CARD AMAZING ^ ELECTRONIC "9^ PRODUCTS and KITS Rememter Ihose Martian Space Ships in HG Wells War of the Worlds? MYSTERY Levitating Device Objects ftoai on sir aid move to the touch. Delses gravity' Amazeng gifi, corrversalson place, magic trick or great sdentitic project. AffllK Easy-Ass y Kit PlaF^sS19.5Q 3 MILE FM Wireless Micropfione! crystal clear, ultra -sensitive pickup iransmsis voices, sounds to my FM radio. Fof secunly, rnonaioring cJ:i!dren, iftva3kte. Be Ihe local DJ! MVP1 Plans %7m MVP1K Kit/Plans . ... S39.S0 a MILE Telephone Transmitter! Aulomaticasiy Eranssnits 2 sides ot phone conversation to any FM radio, Tunable, easy-assembly PC board, Operates only when phone is sn use.. VWPM7 Plans ....... S7.00 VWPMKTKitPlarvs $39.50 TV & FM Joker/Jammer Pocket Size device lets you remotely disrupt TV or radio reception. Great i gag! Discretron required. Easy-buik) eledronjckit EJKIK M .... $I9>5 0 100,000 V -20' Range Intimidation Device! Electronic n^ute, may be enclosed for harxlhefd, portable, or bed uses ITM2 Plans {creditable to kii) $10.Q0 rrM2K Kit & Plans , $49,50 READYTO-USE, AUTOMATIC Phone^Recording^^ Corrvp^ete wiih e!(tended p!ay tape recorder & line interlace switch, Aulomaticaity records twth srdes of conversaiion. Che-ch Local Laws on Proper Use! Read/ to Use Sysiem, TAP20X System , . St49J0 Laser Pen Pen sized laser. Qteat lor n^ovtes, drive- ir^Sn pointer. Ready lo use, with ms. LAPNl L aser Pen . SU9 ,50 Pocket Laser Kit 3rrw or 5mw kits, with soSid siaie 670nm diode. Caution. Class lila i terry VRL3KM 3mw User Krt , . , S99.50 VRLSKM SmwUs erKH., % mM MORE Laser Kits! LAStKM Imw Laser, 632nm, HeNe Easy Lo Build Kit $69.50 LAS 4KM 3m w V ersion. Kit m SO UT05 Low CosI HeNe Laser Tube! irrrw Tube & Plans . . only S24,S0 Other parts available separate3y Great Lo w Budgel Science Project! Shocker Force Field :jVehicle Electrifier INFORMATION UNLIMITED DeptnE-4 Box 716, Anihersl NH 03031 Phone 603-673-4730 FAX 603-672'5406 MC, VISA, COD, Check Accepted. ADD S5 SftH. V^Order by Mail ail, or t}y "24 H( Order Phone: 800-221-1705 Make hand shoch balls, shock wands e^Jy objects, charge capaators. Great pay back tor those wise guys! SHKIKM Easy-Assembly KilS24.50 CATALOG! with many more items! FREE wrlh order, or send %\ P&H NEW CABLE TV DESCRAMBLER/CONVERTEI! AJX HEW I WBCE WITH *RVMam *PKftmTAL OJWTKOi •[AST at tlBCAU. "fAVOHITC IJ. *SlPfP tlMf.R *JSRt7STr> ISWmifABLE SA snTRMS Ift^OO All Jfftmjll) FJtCOT^ Bit I htm ilENITJI/TtMtJM tiST CHIP W (MJ OR 1(1 2^.m tlA CO,D. ORDEES Ot S.A.C. ^-622-3799.. M-F 7A-3P SURVEILLANCE transmitter kits tur;o from 65 to 305 UHz. Mains powered duplex, telephone, room, combination telephone Toon^i. Calatog wilh Popular CoTTimtinications^ Popular Elec- tronics and RadEO-Electronics book reviews o( "Electronic Eavesdropping Equipment De- sign," S2,00. SHEFFIELD ELECTRONICS, 7223 Stony Island Avq.h Chicago, I L 60549-2806. SATELLITE TV do scrambler. Build your own. Easy to follow inslnuctions. parts list, circuit toard, wiring diagram. S9.95, ABG ENTERPRISES, 27081A. Halifax, MS. B3H-4MS. REMOVE LEAD VOCALS Calt or vrrEto for froo Info (513} 444 2^7 B Buifd ihJs hit which removes lead vocals from slandard stereo lecords, CD's, tapes or broadcasts, Sing along with the background muEic. Use with any home component stereo. AddilionaJ kit adds mv^tb to your voice. Ihen miifes it witli musk:. PrG'Ss^embtcd boards available. Weeder TtchnoEogies; 14773 Und- seyRd.; Mt, Orab^ Ohio s? I g X3 80 PCS and schematic CAD. S195,00 IBM EGA CGA Multilayer, rubberband, autovia, NC drill, lasor. dot matrix, plotter, librafy, Gorbor. AUTOSCENE^ 1056S Bluebird St., Minneapolis. MN 55433, (612) 757-8584 free demo disk, DESCFtAMBLER kits. Complete cable kit S44 ,95, Gompleie satellite kitS49.95. Add S5,00 shipping. Free brochure. No New York sales. SUMMiT RE. Box 489, Bronx. NY 10465. VHF amplifier plans 75-110 MHz, 15-25 walls. S8.95: PROGRESSIVE CONCEPTS, 1313 North Grand Ave.. ^291, Walnut, CA 91789. CREDIT card encoding, standard explained m plain English. I! I ustraltve examples included, send S5.00 BSC, Box 1841, Alexandria, VA 22314. ^ * * * * PRf SEWTTNG ★ * ■•r * CABLE TV DESCRAMBLERS -|t***-ts STARRING *^c-|rlr* JEffROii}. HAMUN, CMK AND OTHER FAMOUS WAN UFACTUflE RS ' FirsrEST W.'M?SANTY f-RLX^k^^A AVAILABLE • LOM/EST PETAJLliaiHOltSAiE PiSJCES r,'SrUS • ORDtW SHIPPED FROM S^OQK WrTHlN 24 Hfii • AU MAJOW CfifOlT CARDS ACCEPrEQ FOR ALL INFORMATION 1-800'345-8927 PACIFIC CABLE CO., INC. 7a25'/2 Reseda Blvd.. Dept. 21 13 Reseda, CA 91335 DEFEAT videotape anti-copy PCB PAL insiruc- tions $16,50 w/P&H LOGICAL CHOICE, 955 NW Ogden. Bend, OR 97701 QUALITY new plans Msao and resirtcted de- vices Caialog Si .00 KELLEY SECURITY, INC., Suite 90, 2531 Sawtelle Blvd.. Los AnqeiOS CA 90064. VIDEOCJPHER ll/scanner/cable/satel)ile modi- ficalions books. Catalog — SaoO. TELECODE, PO Box 6426-RE, Yuma, AZ S5366-6426. KENWOOD & Jcom service bulletins. 175 + pages covering all -models. 533,95 caialog — S3,00, CODs (602) 782^2316.Fax (602) 343-2141 TELECODE, Box 6426-RE, Yuma. AZ 85366-6426. CABLE TV DESCRAMBLERS ★ CONVERTERS^ and ACCESSORIES. SAVE MONEY. PANASONIC, JERROLD, OAK, PIONEER, SCIENTIFIC ATLANTA AND MORE. LOWEST PRICES. FREE CATALOG. CABLE READY COMPANY (800)234-1006 / ELECTECH f CABLE T.V. DESCRAMBLERS - All quaUty brand names * * All fully guaranteed • All the time * Knowledgeable Sales Service Department FOR FREE CATALOG 800-253*0099 WANTED INVENTIONS; new products ideas wanted: call TLCI for free inform at ion Inventors nowsSetler 1 ^800} 46B-72QQ 24 hours day - USACanada, INVENTORS: We submit ideas to industry. Find out what we can do tor you. 1 (BOO) 28&-fDEA. INVENTORSJ Contused? Need help? Call tMPAC for tree tnfonnalion kit, USA CAN ADA: 1 (800) 225-5300 {24 tiourst). SATELLITE TV NAME BRANDS AT 50% DISCOUKT This FREE 1^4 page Consumer Buying Gultle tells all ahaul Satellite TV and lists guarantee ta lowest prices. 5310 U-^'.-^'? ^ - ^ JL 61612 1-800-472-8626 J I -'30 ■• I U*S« SAVINGS BONDS BEST BY MAIL Rain: Wfit* MtUoniL Bqa 5, SarflBOla. FL 342^0 OF INTEREST TO ALL VCR fiEPAiR ^TtCHMICiANS" SECRETS REVEALED Do n ty txi&ineu! Compiv\9 sftiy to tollow MAN U At -miih ScftemtticsTOiiprams. Inciiioai BOO numbers of t\\ nupt mangJ»«uf«f» fbf oniwifw pift« mma. More Su 95 tqc ACME VCR Rf PAia 2T0* Rftnwidc Lane. Antioch. CA g*509. RETIRE EARLY iWTT^SUA CODE AB 5160 M«fttkin TOOLS CORDLESS SOLDERING IRON, irvmsss motaatv. im- McGfegsr J m porta. PO 4ai3SS. Chlciqo, IL 60642 MONEYliAKIWQ oppoimiiimes GET PAJD FOR slufflfig wivelMies! Ffee detilla. Whte: StufMt. epy g7e^m Graham^ 7X 75*50. TRAVEL 50% TRAVEL SAVIN QSf INFORMATION SIjOO: LUDLAM. CHICAGO, IL 60630^1424. ANTIQUE RADIO CLASSIFIED Free Sample! ^^i" . Antique Radio s ^-^^^C^^^ „ _ ' Articlos. Ads & Classitieds. 6-Monih TriaJ: StS* l-Vr: S27 (S40-isi Class), A.Fr.C, P.O. Box Q02-L9, Carlis[e, MA 01741 BUSINESS OPPORTUNITIES YOUR own radio station! Ltcensed unlrcensod AM, FM. TV, cable. Inlormation Si .00. BROAD- CASTING. Box 130-F^. Raratiiso. CA 95967. LET in© govefnmeni f (nance your snnaJl business. Grants loans to S500.CXX) Fpee record^ mes- sage. (707) 449^SS0Q. San Frar^ci^co. CA 94126. ELECTRONIC engineering. 8 volumes com- ptolo. S109 95 No prior knowledoe roquirDd, Free brochure. SANMER TECHNtCAL BOOKS, 12CO Gram Avenue, Rock ford, IL 61 103. BIG SSS SSSSSS. VCR- slereo, TV repair IncwJi- blo mfinual filled wilh the latosi repair tips. Reces- sion proof yourself Reduce imports. Only $39,95. BERGE SYSTEMS. Unit 342-RE, 253 Coltoge. Tororilo. Onlario, Canada, MST IRS. 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TA 1SO0 TA 3600 TA 477 M«talCatvie! AMPUFim mm Mm rtigrtJi VWf W*mri AA Mult Pmpcia hlfioJrOtmriliiii i,W«riue pmiBtTiiJumjiwcDS S MARK V ELKCTROMCS, INC ORDER IN CALIFORNIA 1-800-521 -MARK ORDER OUTSIDE CA 1 -800'423.FIVE CATALOG £ tKFORMATION (213) 886-3988 ORDER BY FAX (213) 838*6363 ^ Q CIRCLE 33 ON FRE£ INFORMATION CARD 89 DESCRAMBLERS [ MAKE THE COHHECHOH NU TCK ELECTRONI CABLE TV EQUIPMENT I OR»l^:il TOLL FRFE 1 -800-228-7404 DON'T FORGET TO ASK ABOUT I _ . FREE CATALOG WIIH &UY1NG GUIDE FRIENDLY, PROFESSIONAL SERVICE 30 DAY MONEY BACK GUARANTY BEST PRICE - BEST SERVICE m fKTSSt ico.D mymtmrnti NU-TEK afciROMcs l-^llQ.OVuyi'^l BWjxfe WOOD dr. I %I IL L^ATWJ I I3C7 DEP Mum tStAS 7IW SECRET cable descrambler Build your own do- scrambler for less than $11,00. in Sevan easy steps. Radio Shack parts list included. Also tree descT^bltng rnelhods thai cost noticing to try! SefidSlO OOto LOUIE WHITE, 2Mar)in. Baylown. TX 77520. FREE CATALOGI 1-800-648-7938 JERROLD HAMLIN OAK ETC CABLE TV DESCRAMBLERS * Sp&dAf Prices! • Compm out Urn Retmi Prices! * Gusmntemi Prrc^ & W^frmtiesf • Oftiers Shipped tmmetAe!^ REFUBUC CABLE PRODUCTS, INC. c=a 4080 Paradise Rd. #15. Dept R£*I2 E! Las Vegas, NV 69109 CTa For all Other information (Ttffi) 362-9026 CABLE TV -800-582-111 4. FREE CATALOG GUARANTEED BEST PRICES • EHMEIHATE SHIPPING r— .M.K. ELECTRONICSsa 8363 fHnei BJvd. Su.re 3« ^Sgl P*Y TV ANO SAIEU17E DESCRAM&UNC AaKEW 1992EDfnOM ALL NEW cjvwt^e biAct tost. Dk*k. Uetnir OntfcVf SSJ9 ijianitfijif «0asi;.K-torl^3Spf 6>'»9» VtiM 5eniii«liB9llf«,1^jtertilAMi. 1 ftneahi. lev. 14216 Uak«/fte(Tl«] i74-m 1 INVENTORS INVEWTORSI Can y(xj patent and profit from your idea^ Call AMSRtCAM IKVENTORS CORP. fof free information Scfvirg inventors Since 1975, 1 (SOO) 338-5636 SATELLITE TV VtDEOCIPHEfl U,ifmwv)biifig manual. Sche- rriatics. video, and aucto. Explains D£S. Eprom. ClofieMaster. 3 Musketeer. Pay-por-view (HBO. Cinemax. 5tx>wtime. Adult, etc) S16.95. S2 00 postage. Schematics for Vitteocypher Plus. S20.00 Schematics for Videocyptwr 032, SlS.OO Collection of software to copy and alter EPROM OKJes. S2S,00. CABLETROftlCS. Box 30502R. Bethesda, MD 20824 CAItl.K 1 \ DKSfKAMULIUs BEST BUYS BEST SERVICE auLL=T PROOF TV TEST ED WAJfT TO BUY: TOCOy. SA a5Sa.0I^V7312 C-iJpsCTSefHJit<»Ta Wtfttt-VlHon {402)33 1-322£ Ei«lroFiic»™ 2730 SO J2Jrd Dtmltn HanUd ^ 800-«35-2330 T>ttS A REGULAR TYPE BOLDFACE AD with a tint scmea To have your ad appear like this one, the cost is S4.15 per wOrd> BUY BONDS 90 Triplet DMM lafoe, easy to roAc! 3-1/3 diglLCDdisp<4-iy. Tests WW WW ^ & rango^ ta l«ft w(lh autfM oomln^tty. a cut ronl r&nges to 10A. Biifrt'lnbsnoryrostaniJ L^^io^trrnKPN and PNP tfaoslator*. Te*1 fwuJs, kiaiructions and cQffylrg cjiao Included ► Infrared Detector Pen ThQ worldii llret handheld. BAlltpry powor«d. Infr^iRod OotdctOf pon. In^ktmly ^mrognlio} infrared lighl ?rom lolovlsloriH VCR, njid sleroo rerr-o^o canlrol«, VCR Icipe slop drcuilJi, alarrn penmeter deloclflrs, and Ihouaandi of cither IR contion^d pfvductt. AlJcwt you id oanf irm the preuficvQf hfpv«d kn norrria] roomTtghting. Sim on« hantf cp«f atbo matos it e«*y to re^ich in ofTiiaft ofl c rt w w i VCR tapa inecharttsms. A cariying cait to protect and inuispori your O.I,R.O. is ^oHabCo f 0^ S3.gs. order iSdO-ao I . $34^ Each #RD-390^200 IC Protector Kit Corverent iaj-of'merii or 60 C pro^octon lor ^ja,, carroonSen and VCAs. 5ea£hof I2dtter«nt (jfofBCScwa: ICP FlO. JCP- Ft5. SCP'FM, ICP FZ5. - ' ■ ■ ■ ■ ip« ICP F3a. ICP FSO. [CP F7S. ICP NS, ICP-MO. ICP-M15, ^CP N20 arid (CP ^25, A *45.00 vatue. #R[M)70-S45 ^^Parts Audio/Video Cable Checker DonvqnSont l&ster cii^cM cable lof coniiiir oortducror apd shiofd oontinutty. Tests al BfJC.'F', RCA. 3-5mm mW, fi IJKF, ai>d phone c^tes, Opera;t^ on iwo AA batfe^fe*. Butl^■l^^ baltary lost lur^dlon. #RD-390-250 $21^, Each 3.5 Amp DO Power Supply A{^ua!(Ey. conpacl 12VDC po*«r Suppt/. Periect for leaiing car s^aiegs. CQ oquipment. radar deteclors and othor ("Lams, RaguCaiad riaVDC. arrp continuous. € anp tfeirgjo. LEO powof tntJj&slOf * iindJngposl #RD-1 20-500 $23fach 3-Way Bookshelf System High quality, high ipAaher «ysl«fiL d*cas4 aiyrfinum cor^uctioa, Heawy duty wire mesh grfle. 3D wans RMS. wans rnax. T'xS'jt^'. Sotd In pairs with rnounting hardware. Nsl tAetght: Q Bjs. per pair. #R0-31{H)1Q S37« '/express Pressf it Speaker Terminal No re I CO Type Boxes Spdng loaded, pushbutton apoaxar terminaJ m a round housing, Uo screws required to fasian; smply drill a hoFe, apfily 0lue, and pro&B lnloplac«. #RD-260-295 95|, ach Standard roplACorrion; pJa£tct»K for cs&seltes, Slack base wirh ctear ic Mada In the U.S A. #RD'200-060 24 Each Pioneer 4-1/2" Full Range This vary pcpuLarMooiof is parted for mnkfng bookshcfll spoakor^or tor caf s^(^r^?o ir^laltitior^S, noapome: 70- 15 KMl. fs- 70 Hi. 20 watts RMS. 35 WiUlEmax, SPL- OOdQ IW'tM. lOoi. rnagnot. B ohm Impodanco. Plonear iAi^ECeO'O^F, Noi weight; 2 bs. i^RD-290-010 $9f^^ 18" Eminence Woofer Ba^ i^lEe^ vtOf^m rtjbed paper oDfie ajid troaied dcHh acco'^ion surRHifld. Giant IOOd;. magnet. 200 watts RMS. 300 w.itSji majt, X , 2 layor v^co co^l 8 ohm Impedance (7,5 ohm DCR) FfOOuerKy rirtponso: 27-3,000 Hi. Is- 2S,01 Hz, #RI>290-200 S99f^,h 12" Pioneer Subwoofer ? IT tuper di;ty. duat votce ood sUHwnf er, 30 oi. magnet. T voice coO. lOOwaltt HMS, 145 watts max. 25 Hz rasonant fiequency. 6 ehm ImiMdance (4 and B ohrn corrpatl>l»}, ~ Responsa: #110-290-145 S«n$ithr«^ 94 tfB tW/IM $39g 340 E. First SL, Dayton, Ohio 45402 LxkcaJ: 1-513 222 0173 FAX: 513-222-4644 • 30 day ^T^oner c^a.-^'^ * SSOilOfnMmtfn ofdor * 1^ 4ecapi Masteruadf. Dtscow, afid C. O D. orders, * 2A hour th|]|]ing - Sr pp^nq d^a-ice • UPS chart ra!« • Si .00 (S3s50frftiniiiRich3He] * Hours a30am - 7^X1 pm EST, y ondar < f rkfay - 9££i am - ?.00 pm Saiufday, Mai tf S5^ U S. f^fii^ c^LiJog pQSlaffa • CALL TOLL FREE 1-800-338-0531 FREE CATALOG CIRCLE 5a ON FREE INFOfUlATKHI CAHO CORI\ E C T R 0 N I C S lOOlO Canoga Awe . Unit B-8 LASER DIODES STOCK * MFG. WAVE- LENGTH OUTPUT POWEfl OP£ft. CURR. VOLT. 1-24 25-99 1004 LS9230 TOSHIBA 3mW AS mA 23V 129.99 123.49 111.1* TOSHIBA GTOnrn 3mW «SmA ijv 49,99 47,99 43.19 TOSHIBA SfnW aOmA 2.< V 59 93 51^ TOSHIBA 67Qn VftrWe DC oulpul ' lo - 15 VDC ii> 0 h amp^ fippte - 5mV WAG II PROGRAMMABLE ROBOTIC KIT I OESCRIPTtON Wll AP IntsftKO till fcf Ap^ a. tiE. ft- The pen mechanism ciLkdetJ wilh the robot allows il 10 draw In addrlron toOrawmg ^Iraight hrm, it cirn 3lso accy- raioly dr^w Ct^ci05. and even draw out words and short phras4*s WAO II comes with \2SnAbtl^ RAM and 2K ROM. antJ fs prog rammed directly via tn<5 keypiid attacheti lo iL Wdh I Is bu i ll 'in connector port WAO H 1$ ready lo Commynicale with your computer With the Optional inlorl^ce hiL vOu e^n ccnnoct WAO H to an Appfe II. IIO. Orlh computer Editing and tranjfcrrng of any movement progr am, as nwU saving and loading a program c^n be pcrtofmed By Uw mterfaiis kpl. Th« ^it mcludes software, catit«. card, ind^ instfuctiom. TlW pragrtmming langi^e is BAStC 1<9 10-34 2St Irec^jency range Q i to 100 KH? n 6 7^99 3999 7199 37 99 ^J39 34 19 • The total fleijgn wo ri^sl Alton - incSufling tfupflnded mtitrumentalion. breij^dboard nna power supply • IdQal tor analog, dl[fitiit and mioro- processor circulia • a logic probe circuits • Function cjon^rator with continuously vflrtabfe size, st^uaif?. triangle wave lorms, ptua TIL pulsus • Tripfe pcmirf suppty pltos fixed 5 VfXI wjpp'y plus 2 varijbNj outputs - ^5 ■ 15 VDCaniJ-S- 15VDC • e TTl compatibkj LEO indtcatorsi, swrtehes • Putsefs • Potonliom&lcra • Audio cxpcnmenl^Iion speaker • MollipSe fe.alurcs in one Domptete test g ifti 2S2Q uncctfnmilt(*!3 tie points 1 1 5" tong jr 16" wide * 65' tugh 3 wtfC AC tm* input ( 1 1 7 V. to Hz ivowafj i-f 10-34 as* [ P8501 Prototxianj Design STstior: IDC BENCH ASSEMBLY PRESS fti* Paf-ai?w T J T-,r. iMion iDol dnignvd tt.< .j. * Aaaemb^y ti«ei & lUmda'd * Bw plate & ptetin miy tw rotaifittwr lor mtimHint sones ane qu'cMly Ctwinged Aithcut s^t\Y tciol* riKtiiirijd > Af^itionat accesioncii bolQw * Slid - 10" W t B7&" El ji J" H * WeigtiE -5.5 itra m OOLUMATtMG LENS COUJMAT1WS PEN cvv output pow of £5 at Ud nm 1h« Qptfiibng voiCngB cd ? ?-?£v {ni) go^tSfimA It dtMflcd tor tcmi^ powvr jpptkcOitiDrii aucn At d4ij rtrifi^v^dP idwTKify, a»9rHii«iit etc T rw mxytimm&ttc tatritn tied cue is 3]Mef4 »nd a Ustit 4tvi9 Ttifl lent iirtM^ coiiirTMitn itiQ Ej/wer^' infl ludT i^rit Tfl mraci The ^avATfonE >qij[3l>ly li d||i be adjusied la Iodl» thi^ bram IQ t tpoL Sluf]!/, P-ma,ll aTit( seM-con' fnincci, im LDMl^ is a p.fH::»ioii i$ fiHTrm ]j« • WE CARRY A COMPLETE LINE OF ELECTRONIC COMPONENTS •NO SHIPPINC CHARGES ON PRE-PAID OROERS DELIVER€0 IN THE CONTINENTAL U.S. 91 CIBCU m ON FREE INFORMATION CARD THE ELECTRONIC GOLDMINE Vte xan UC, VKu and MonAy DOM PHONE OROetS (TO iSV7«l fJU OflOOS «G0] Vl'W CIRCLE 182 ON FREE INFORMATION CARO Cabie TV Descrambler Kits Universal Kit S55.00 tnciudes bJi pans afts PC Boarc NDt inctudtd Tri-Mode Kit S39.00 includes all parts PC Board and AC Adspipr Not inciudfld IS ihfl anelosure SB-3 Kit S29.00 includes ail parts PC Board and AC Adtpio:. Net tnciud IS tne ensiowjf* Universal Tutorial S9.95 incUjC*s an m afstn »tuay c? tn« lecnpnoiogy uM<] and nas ircubJesnoocing i^ms Tri-IUlode Tutorial. „-,„„S9.95 inciudies a gaie gaie nudy of the cflcuri and na$ lrei«>»Mnooting hnti Snooper Stopper ....S39.00 E^ect yoursatT from aescrambie' deieciion and itop ir« 'Puller Call Toll Free 1-800-258-1134 Visa, MasterCard & COD M & G Electronics, Inc, 301 Westminister Street Providence, RL 02903 FUN WITH ELECTRONICS coMsntucnoK uahual _ SS^ Hpm to m*M! HE ff^. KX»o flnd ponver CDi»L cjMA» «nd tamtonniirs. PtictcaDr «^r¥ posvbl« typv ib c9I«- , PCPn3— THE PC MUSIC HANDBOOK .... StlflS, Lcam Ihe tasKs oJ cofnputiiir tinusic systefTS Fof Wo prp- B P2 97-- LOUDS f>£ A K- EirS FOR MUSICIANS .... l^aSi toiickspea^ 'our taxes, you don't have to do ihem alone. There are IRS-trained volunteers to help you. So the only number you need to know is on the coupon above. Cut il out and cut down on your tax worries. Call us and we'll direct you to the volunteer site nearest you. The IRS-trained volunteers. They'll make your taxes less taxing. MAKE YOUR TAXES LESS TAXING. CIRCLE 195 ON FREE INFORMATION CARO COURTEOUS SERVICE • QUALnY PARTS • DISCOUNT PRICES • FAST SHIPPING Electroluminescent BACKLIGHTS INFRARED Remote A.C. SWITCH A! Ia£t1 Alow COS! eLsdrioluminesoBm glow mtp and invener. Th«fi0 brand- rmi unitE were dsslgned to backl^he smnS LCD TV$ mada by tho Cilf7en Wnich company, Thm invefiordrcuit chtin^)fr& 3 or 6 Vdc to approstimaTely 100 Vac, Ihs voFtagB required to Irght the gkswstiip. Lumir^escsrn aurfaoe area is 1 .7" X 2.25". The strip h a sarrnon color Jn iflii dT stale. arxJ gJaws wtilte when »nefgij»d. The circuit board is 2^ XV. Glow strip arxJ drcuitry can be rarnoved eisily from plasl^c hotissng. ideal Tor special light tfig eMocts. C iSzen* 9 1 TA oper ales on 3 Vdc CAT* B L U-91 £ 950 Cflizenf MTA opofftteson 3^Vdc CATi BLU-92 ^ 9 ilioh MTOf QUANTITY AVAiLABLE 10forS32,00 - 1 00 for $275,D0 2 fof *17.00 TTiis Mrared romol&coniroJ (Jovlca let$ yoy turn Ofii'otf Lanp«., appliances Of other 120 Vac tSevices usrng an IR transmtjor simtar to ihe one on your TV Of VCR. Ong^ially designed tor u&« wiih a hydr^jmassage unii, ihese tranamittefs arid Tecejvofs will apparenJly operate rrto&t A.C. devices wph 2 prong r»on-pci!.-irizod p3ugs. Noi recommended \of ue-e wilh heaJers. Re- quirtts. a 9 volt battery (noE Irtcludod). UV "Invlsable " INK Whfrn The jik dries (he writing el t^ose tett lip pens is v^ble onhf undef a UV Tjfaok bghr. Originally for marking par&onat twlongings in case d Ihed. these pens rrsight a%o be used for writing sacrel messages nwk- ing merchandise for inveniory csnEfok Large quanlttiefi available, CATKUVP 3fofSl.0O - I00for$25.00 Wireless Remote ConOvt FOR NINTENDO™ CAM ERICA "Freedom Connection' ™ Turns your wired Nintendoi*f comrol pad- dle into a remote Contjgl unlx. [nfrared re- mote ikB I hose used on TVs and VCRs eFtrnrulefi messy wires. Anowsplayefs more mobility. Two players can use one remote unit except on game* where they pEay s Imu hianeously. I n those games iwo "Freedom Conned Ions" unJts are re- quired. A wef^know^ naJionaJ discount toy chain sens thesa for more than twice our price. Operates on 4 AAA battene« {noUndjded), CAT*IR*1 59.95 FLASH UNITS NEW conpaci Elash assemblies Iroma Camera manuiactufer. Operates on 3 Vdc. Measures a t^ X I U4\ ld«il lor use as a strobe, warning light or atten- lion gehar. 1ndude$ a hoo^^up diagram. CATifFSH-l $3,75 each 10!DrS35.00 " ^00 for 5325.00 L.E.D.'S Surface mount . -.^^ LEO chip. Clear when otf^ green when (it. Very tiny - whole unit is ail5"XO,OS5'XO.05'lhk:k 1 mm {0,04') lens diameler. Goif^pLated fraunllng surfaces !of superior condudk^fty, CATiSMLED-2 I0lori2.00 lOOIorSlfl.OO 1000 lor 5140.00 Standard JUMBO Oil^used TV3^4siie(5mm) RED CATf LEO-1 tOlof * iOO lor 513.00 GREEN CATfLED-a 10 for 52.00- 100 for $17.00 YELLOW CAT* LED'^ 10 tor 52.00 * 100 lor 517.00 FLASHtNG LED W bm in flashing cwcuJl 5 volt operation. T 1-3/4 RED 51.00 each CATtLECM tOtorjS.SO GREEN 51 00 each CAT# lED-4a 1 0 lor 59.50 YELLOW 5 1.00 each CATiLED-4y 10 for 59.50 LED HOLDER Two piece ho^def. m CAT* HL£D y 1 0 for GSc O.C. Wall Transformers (120 Vac INPUT) I Electret MIKE Sryla Pflc* 4 Vdc 70 ma. 2,5rtyn co-at r^egalrve DCTX-470 5200 evdc 300 ma. 2.1 mm co-ax posit rve DCTX-632 52,75 6 Vdc 750 ma. 2-5mm co-f« negalrve DCTX^7S 54.00 9 Vdc 10 ma. battery snap DCTX^aiO 51,50 9 Vdc 3O0ma, 2:1 mm co-ax pcsltP/e DCTX-&32 53.00 9 Vdc 5O0ma. Z5mm co-K positrye DCTX'950 53.50 9 Vdc t An^ 2.1 mm co-ax negatpye OCTX-910 55.00 12 Vdc too ma. 2,1rTUDCO'a3i negatr^fe &CTX^i2lO 52.50 12 Vdc 200 ma. ^imm a>ax negative DCTX-122 53.00 12 Vdc 500 ma a 1 m m co ax negative DCTX-12S 54.50 High elf ic»ntcy. orrmi- directbnal . mm latu re jflb electret oondensei L_J rricrophono olemanL Lowcurreni drain, good signal to noise ralio. operates on 2 to 1 0 Vdc. Ideal for telephones, tape recorders, noise- aoTivated alarma artd other app&oi,- Tions. 0.39" dm X 0,31" hi^. CAT«MJKE-H> SSeeach 200pcB 5 150.00 {75c each) HE A T SINK COMPOUND G C Eleclronlcs f 10-61 09 - Fof elfecth/w transfer of heal between convofienls and heal sinte. 29 sificone heal Sink compotj-nd. CAT* hSC-1 52.00 per 1 0? tube RFt/EMl LINE FILTER Corcom* 2066 20 arrip RFI^EMJ general purpose commgn^rrode liJier. Conlrols linfr to- ground noiae.SrraJI sCe. -low leakage. 3.4e- X M6" X 2,81'- UL and CS A Jisted. CAT#RR-301 5e.50eA:h PHOTORESISTOR 1 K ohms ligtit, 1 5K ohms dark. 0.182" dia. X.Oe^ high. 0.18" iong leads. CAT# PRE-7 100 lor 545 00 ft* 1000 for 5400.00 DIP RELAYS HALL EFFECT SENSORS MJnialure Relays Wi^h P'm Confi9uraljon To Fil 14 DIP. SVdC'S,R$.T, G\ Ctare * PRMA-1A05Q. NormaJJy cpen reed relay. 500 ohm co"l U, Sisi od . Diode protected, CAT* DflLY-S7 51.50 each 12Vdc-S.P.S.Z Gordosf &4eA-412 575 ohm coiL SeaJed. internal darrping diode. CAT*DRLY-12 $1,2$ each 24 VdC'S.P.D.T. Gl Ctare * PRUA 1C24 2J&0ohm odeL 10 vA switching power. CAT* 0RLY-1C24 51,00 ea. 4BVdc-S.P.D.r. Aromal f DSlE-A DC^flV 5.750 oftm coil. 2 aJTp con ^ :1s. CAT* $1 UOpiicn Mk;ro6witch *SS4t Tiny, sofid stale swisch reacts instftntly to proximity d rmgnetic lieid. Operates at eitl remedy high speeds, up to 100 khl.CaAestze:0.12-X 0.1 r X 0 06' thJck. 4.5 Vdc 10 24 Vdc supply voltage. 10 ma. sinktype digital Output. Operating gauss ' IS to 40. P C. leads. CAT* HESW^2 75eeach 10 for 56,50 - 100 for 560.00 SURFACE MOUNT STY L£ Q Sprague* UGN3075LT Operates on 4.5 - 24 Volls Can slnV 10 ma. Wflh suitable output pui up. can be uf ed direct^ wuh bt-pc^ar or CMOS logic dicuits. Espedaliy surled lor electron k; com- mulalion in bnjshless D.C. motors us- ing multiple ring rriagnets. Very liny surface mouni package 0.1 75' X 0.09" X 0.06" thick. CAT*HESW-« 2h>r51,00 10O for 545.00 iARG£ OUANTfTlES AVAILABLE RECHARGBABLE BATTERIES (nickel-cadmium) , AAA AA AA wf Solder Tab* SubC w/SoiderTebe C C Hetvy Duly O D HtJi¥y Duty 1.20 liOmAh ^B-AAA 51.S0 513 50 1.20 500 mAh NCO-AA J2.00 516.50 1.20 500 mAh NCB-SAA 52,20 520,00 NCe^G 54.25 540,00 1.20 1200 mAh NCS-C $4.25 540.00 1.25 1600 mAh HDNCB-C 55,25 54 ^50 1.20 1200 mAh KCB O 54.50 542 50 1,25 4000 mAh HDNCB-D 57,00 56500 Highest Quality METAL CASSETTES Prenlum qiuality nnetal tape En C-€0 style cassettes {30 Of more per side). One of Ihe (jnesi "brand- narno" tapes on the rnarkrt, in durable^ dear pbistic ^ ^ - — IransppFl mednanisms. Recorded and; bulk erased, she reoofd-pfoted labs 2S have been removed and thefefoie. need lo be taped over to re-record. ■ -.^ - Audiophtles will appreciale the wide dynamic range of Ih^ tape. U your cassette dedi has a 'melal" settirig you will hear the dlfteienoe, A renJ bargain 60 min, Irpe - CAT* C-600M 10 (or 51 0,00 CASSETTE STORAGE CASE Black, unbreakable plastic audo cassette storage case. CAT* CB OX 5 for 51 00 * 1 00 for 5 1 5.00 ORDER TOLL FREE 1-800-826-5432 FAX (818) 781-2653 • INFORMATION (818) 904-0524 Call Or Write For Our Free 64 Page Catalog Outside Ihe U.S:A. send $2,00 postage lor a catalog* Minimum Order $70.00 * All Orders Can Be Charged To Visa, Maswrcard Or Discovorcard * Checks and Money Orders Accepted By Mail • California, Add Safes Tax * Shipping And Handling $3.50 for the 43 Continental United States - M Others including Alaska, Hawaii, P.H, And Canada Must Pay Full Shipping * Quantities Limited • No C.O.D. • Phces Subject to change without notice. MAIL ORDERS TO: ALL ELECTRONICS CORP • P.O. BOX 567 • VAN NUYS, CA 91408 93 C*RCLE 107 ON FRCE IMFORMATION CARD DESCRAMBLERS All major bmnds carried ♦JERROLD. *TOCOM**ZENmi •GENERAL INSTRUMENTS ^SCIENTIFIC ATLANTA, *OAK •HAMLIN, ♦EAGLE, *PIONEER 7ih Year in business. Thank You Member of Omaha Chamber of Commerce I Year waminiy on new equipment 30 Day money back guaraniec Ordcfs shipped from siock within 24 hours CALL TODAY FOR A FREE CATALOG 1-800-624-1150 S ^ E C.O.D- ^ jv STS SO. 72nd SL Omaha, NE 68114 3 til g IT 34 CtRCL£ 53 OH FREE INFOItMATiaN CABD "CABLE BOXES" BELOW WHOLESALE GUARANTEED STOCK - COD'S DESCRAMBLERS (QTY) (10) (20) (40) NEW TBI-3 70 55 GALL TB 2 or 3 45 40 CALL SA-3B 45 40 CALL OAK N'12 43 38 CALL SB 2 OR 3 43 38 CALL COMBINATION UNITS DRX-DIC 89 CALL SYL Die 59 CALL PIONEER 295 275 GALL - CONVERTERS W/REMOTES - PANASONIC^ T2PC14$ 65 60 CALL STARQUEST- E'Z550 65 60 CALL BZY550 75 65 CALL TH£FT Of SERVICE tS *■ CAlVE MfiTiLiLlNG Am DEVICE WTTMOm l»ERUt5S«0*l MAt SyUECI VOU TO QVlL OH CPnVtflAL MALtlCS YOU UVST C**tCM. Wrr>4 vQciH LOCAL CAVLC CCVPAMf 4H0 tAV tOfi «4L SCAVlCE tCU LES£ IT IS t«OT fHC tHTf NT OF UMC SYLVIM TOOEFluuO AHT TEL£viS«>liOP£IUTCfl *MtWt IwOT ASS^T JLNt COUPAHt OA iNQtVlOUAL iH OOWO THE SAUE LAKE SYLVAN SALES, INC. sonFiy NO MiNi^EsorA sales CALL FOR A CATALOG NOW!! 800-800-4582 ADVERTISING INDEX RAD10*ELECTR0NICS does not assume any responsibilrty for erors that may appear in the index below. Free Inform at ton Number Page 108 AMCSates 67 75 A(K Products . . , 69 I«7 All Electronics. ...93 — Amazing; Concepts 88 181 A me rican Reli ance I nc 69 77 B& K Precision 82 — Busiite^ INFOUNE . , . 75 109 C&SSalcs 23 — CIE V*.,* S 188 Cable Warehouse 51 — Command Productioiis 67 127 Deco Industries _ 69 182 Elect ronk Ctolditiine . . 92 — KIcctronics Book CTul> ... 76 — Eleclronioi Enj^ineers B.C* 25 121 Fluke Manuraclynog * CV2 180 C;€f dstar PredsJon „ , _ 75 — Gmntham Collefic 22 179 H(?wleU l^ncluird CV4 — High Text Publications, Inc* 73 — ISCET . . . .51 114 J»meco , . H6. K7 187 Kelvin.. J7 191 Lake Sylvnn Sales, Inc 94 19$ M&G Eltttrunies .92 87 MCM Eleclronks , , . 85 53 MD Electronics .94 18J MJS Design 69 93 Mark V. Electrontcs , K9 117 Mouser ........... 71 — NRI Schools 18 71 NTE Elecfronics . 13 1!W OptQclectroniai 7 56 Parts Express 90 1S4 R.L. Drake Co. , 3 78 Radio Shack _30 — RE\1deoOrrer CV3 196 Rile^Orr. 29 Free Information Number Page 185 SCO Electmnics 14 — SlarCirctiib 69 189 TECl 83 92.176 Teklmntx 5J5 194 Cnicnm 91 186 U.S. Cahle 14 I92J93 \lejo Publications .71.73 177 WPT Publications S3 197 Worldi* ide Cable. ............ 89 1 78 Xandi Electronics , . , 69 ADVERTISING SALES OFFICE Gernsback Publications, Inc 500' B Si'County Blvd. FarTnlngdale, NY 11735 1 15161 2d3-3O0O President: Larry Steckler For Advertising ONLY 516-293-3000 Fai 1-516-293-3115 Larry St^k|«r publisher ChHstina Estrada tissistant to the Rncsicfent Arllne Fishman advertising director D«hlso Havcfn advertising assistant Kelly McQuada credit maniiger Subscriber Cuatdmer Service 1*800-208 0652 Ordor Entry for New Subscribers t -600-999-71 39 7:00 AM ' 6:00 PM M-F MST SALES OFFICES EAST/SOUTHEAST Stanley Levitoni Eastern Sales Manager Riidio- Electronics \ Overlook Ave, Great Neck NY If 021 1< 51 6-487-9357. I-5)6'293'30(M) Fan l-516-467-&^02 MIOWEST/TexusyArkansas/Oltla. Ralph Bergen. Midwest Sales Manager Rjid i o- E I ectro n ICS One Northfield Plara, Suite 300 Nonhfield. 11600931214 1*70S^6'1444 Fai I -708 -5 59 0562 PACIFIC COAST/Mountain States Marvin Grevn* Pacirtc Sales Mar^ger ftodto^ Electroni cs S430 Van Nuys Blvd. Suite 316 Sherman Oaks, CA 91401 1-61 8- 98e- 2 001 Fa» 1 - 81S-98&-2009 RE Shopper Joe She re, Na tiortal Representative PO Boi 169 (dyMwird. OA 92549 1-714-659-0743 Fax 1*714-659 2469 CIRCLE 191 ON FREE INFORUATION CARD I 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 counter surveiilBnce, you must view this video presentation again and again. Wakt tip! You may be the victim of stolen words—paxious ideas that would liavc made you very wcaltliy! Vcs, pmfes- sionab, even rank amateurs, may be lis- tening t« your most private con- \XTSiuifms. Witkt up.* U you are not the victim, then you are surrounded by countless vic- tims w ho ne*txl your help ifj-ou know ht>w to discover telephone taps* locate bugs, of "swtcp" a nx>m clean. Tlieix- is a thriving professional servitc steeped in high-tech techniques that you can become a [>art od But hrst. you must know and understand Qjuntersorveiiance Technology Your very first insight into this !ui:hiy Rewarding field is made [HJssi- blc by a video %^HS presentation that you cannot view on broadcast television, 5at- el 1 i I e J t) r cab I e . It pre s en t s a n 1 nfo rm a t i ve program prepured by professional U in the held who know their industry, its tecli- niijues, kinks and loopholes. Mt-n who can tell you more in 45 minutes in a straight lor ward, exclusive talk than was ever arrempted before. Foiling Information Thieves Discover the targets professional srtoo|x:rs seek t>ut! The prey are stoik bmkers, arbitrage htms, manufajcturers, high- tech companies, any competitive industr\', or even small businnesses in the same community The valuable informa- tion they fikh may Ik: marketing strat- egies, customer lists, product formulas, manufacturing techniques, even adver- tising plans. Information thie^'ts eaves- drop on court decisions, bidding inlorrnation, hnaneial data. The list is unlimited in the mind of man — cs- [xreially if he is a thle^^ You know^ that the Russians secretly installed countless microphones in the concrete work of the American Embassy building in Moscow. They converted HAVE YOUR VISA or MC CARD AVAILABLE what I o be an embassy and privrate residence into the most sophisticated re- cording studio the world had ever known. The building had to l>e tcjrn down in order to remtn^ all the bugs. Stolen Information lite open taps fn>m where the informa- tion |x>urs out may be from FAXs, com- puter communications, telephone calls, and everyday business meetings and 1 u nc h t i m e e n CO u n te rs . B u si n es s m e n need counselling on how to eliminate this in- ftirmation drain. Basic telephone use cou- pled with the user's umlerstanduig that someone may be listening or recording vital data and inlorrnation grcatly reduces the opportunity for others to purloin meaningful information. ft A m> EUiCTRONICS V J IMt > OFF RR Wt-B lii'C.iiunTv BM F,Lfm*o|rd4Jr, Nli' tr^5 Plcwr ruih my copy rbr OmntcnunnllAMr Tnl'miquo Vnteti VHS t:aMcttc fat 1^19. pltfs 34 fMt fur [wstjjee ind AimiufU ill |Uf TRcnt f Billm^ n VISA □ MaMrtdfiJ Of a NiJ = l;i|>lrL' t^tr / Siijiiiiliin- ^ N*mc . -m AJtlnrji <^^^^^^—^^^^^^ i ity Sfsrr AW — All iMyrmnr^ ui U.S. A, funth. C^n^dum iuM $ l.tH^ |xrr VMS t.iiHftf. Hti kyn^iji^n urJifa Ntw Ynrk Srau- fr^^iiEt-rKs Tlie pmfessional discussions seen on the TV scrrcn in your home rcvcaJs how to detect and disable wiretaps, midget radio- frequency transmitters, 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 n>om. Today you may have used a telephone handset that was bugged. It probabiy contained three bugs. One wiis a phony bug to fool you into believing you found a buf; and secured the teiephone. The seC- pers that are installed hun- dreds of feer away from the room they snoop on. The professtotials disclose that computers yiekl information too easily. 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