We Only Skimped OnThe Price, Introducing The Fluke Series 10 — From $69,- Actual size: Easy to carry, easy to use iVsMf/ V Chek'*: For fast accurate checks on power sources and supplies, set your meter on V Chek— and let it do the rest V Chek wilf determine comEnuity/ohms; if voltage is present, it will automaticaify change modes to measure Au or DC volts, whichever is detected, for most initial troubleshooting checks, here's the only setting you need to mai®. Fluke quality: Made in the USA by Fluke, with the same rugged reliability that's made us the world leader in digital multimeters. Count on hard-working high performance— and a two-year warranty to back it up. Large, easy-to-read tfisplay: 'lOOG count digital readout Audible CDntinuity: To perform fast continuity checks, just listen for the beep; no need to watch the display. Hewl Mln/Max record with relative lime stamp and Continuity Capture™: Makes intermittent problems easier to find. Records highs and [ows— and "time stamps ' vjhen they occurred. In continuity mode, opens or shorts as brief as 250 ^s are captured and displayed. Capacitance: Autoranging from .001 Ltf to 9999 \iR Uq need to carry a dedicated capacitance meter Forliigh perlormance at Fluke's lawest price, get your hands on tie new Series 10. Stop by your focal Fluke distributor and feel what a poVi^eriul difference the right multimeter makes— at the right price, For a free product brochure or the name of your nearest distributor, call 1-8D0-S7-FLUKE. Seg 95- security accuracy 1.5% basrc cihms accuracy Pa SI continuity beefier Diode Tesi Sleep Mod« Fluke 11 S?9 9s- .0flito599SiiF 4000 ecu rtt digital dtspla'^ ^oEls accuiacy 12% basic acvoKs accuracy 0.9% baste Ohms accuracy Fast continuity beeper DiO'C^eTegl Sleep Mode Two-year warranty fluke 12 vcnek=^ M in/Max recording with relative time stamp Continuity Capture'*' tapaciUnce, .001tiJ9999|iF 4Q0O CQuol digital diiSDl^y 0.9Tb basic dc volts accuracy 1.9% basic ac voits accuracy 0.9% ba&ic oh mi accuracy Fast conlinuity biepar Oiode rest S^eep h^ode TwD-year iiz/arranly Sugi^estecE U S itst pnce The New Series 10. A Small Price For A Fluke. FLUKE AND PHILIPS T I ! E T M ALLIANCE ©1991 Jodn Fluke Mfg. Co.. Inc. Prtee&and spftciflcaNorvs Eubiect to cJianu* Arfrto 00130. CIF^CLE 121 ON FREE INFOI^MATION CARD March 1992 EiEctmnics. 33 MIDI INTERFACE FOR YOUR PC Bring the world of music to your PC, John Simonton 41 SCANNER CONVERTER Get unrestncted coverage of the 800-MHz band! William Sheets and Rudolf F. Graf 53 INTELLIGENT PHONE-LINE MONITOR The Digi-Call logs your phone/fax/modem usage automatically. Thomas E. Black 59 SINGLE-CHIP MESSAGING SYSTEM Add audio-storage capability to your next project! Richard D. Tenney 16 MARCH 10: ELECTRONIC TECHNICIAN'S DAY How you can become a Certified Electronic Technician* Larry Steckler, EHF, CET 46 ELECTRONIC TEMPERATURE MEASUREMENT A look at temperature and how it s measured electronically. Harry L« Trietley 65 WORKING WITH LED DISPLAY DRIVERS An in-depth look at LED display drivers* Ray Marston 6 VIDEO NEWS What's new in this fast- changing field. David Lachenbruch 24 EQUIPMENT REPORTS Dallas Semiconductor's Touch Memory Starter Kit 73 HARDWARE HACKER Using the IC Master, and more, Don Lancaster Vol, 63 No, 3 3' SINGLE- CHIP MESSAGING SYSTEM \ PAGE 53 inTELLlQEnT moniTOR -f 80 AUDIO UPDATE AES: Audio fact and fantasy. Larry Klein 82 DRAWING BOARD Our oscilloscope is shaping up nicely, Robert Grossblatt 90 COMPUTER CONNECTIONS Industry evolution. Jeff Holtzman 102 Advertising and Sales Offices 1 102 Advertising index 12 Ask R E 14 Letters 93 IVIarltet Center 30 New Lit 26 New Products 4 What's News 1 o 9 J The Musical Instrument Digital In- terface, or MIDI, brings together music and computers, and allows a single musician to create the sounds of an entire orchestra. But you don't have to be a professional musician, or have a small fortune *s worth of computer and musical hardware, to take advantage of MIDI Instruments with MIDI interfaces have become common and affordable. Our MIDI interface is a low-cost solution for beginners, and serious users will find it easy to upgrade to meet their needs. For more information, turn to page 33> THE APRIL ISSUE GOES ON SALE MARCH 5. BUILD AN AUTO STEREO AMPLIFIER This high-power, hi-fi car stereo amp is an excellent amplifier design course. CABLE-TV SNOOPER STOPPER Protect yourself against cable-TV snooping! BUILD THE DIGI CALL Construction details for our intelligent phone-line monitor CIRCUIT COOKBOOK More on 7-segment decoder/driver IC*s* Aj. a Mnnce lo r«ad»r». RAD^Q ELfCTRONlCS pubhsh^i tvaitabb pUnj or infom^abon rt1jliF>9 !o newsworthy pfoducii. lfrChn»e^ueT and tc^eniific and 1»<±inolo{}iC4l devflopm^nts Bhdcjiuut of posirble var^nncti irt the ottality and cttHd^tion cl mitviuli And wofikmanihip u»»d by readers, RADtO-ELECIFfONlCS d^i^Lftimt. «riy rvipani^biLtty for the s^fe an4 pnipaf HincUdning madtrnbuili pro|«cti baud upon or front planm or infoniiAljon publimhod in Ihii maguina. Sine? tom» of iht «rquipm«nl an if circuitry describad: in RADIO- ELECmONlCS ni4y rotatit lo m b« covemd by U.S. fHtanli, RAQIO-ELECniONtCS diaclilmt any FiabUity for th« inftingtmgnt of »uch palvnti by thtt mAkii>[|, uting, or selling of any luch squlpnianl orclrcyllry^ and auggfltti that anyone inlereitva in tuch project! coniuh a pAlent allorney, FlADJO ELECTRON FGSh conduciois. rubes, cfyssals. phono carindg&s and »tyli, popular modtjies, evefi SAMS' manuals. There ar^ no posiBge ciiarges of minimLtm reqtrirBmenla for ihis service. Come in IcxJay for deiails! HEWI Micronta^' LCD Digital Multimeter With big display and proiecttve rubtjer holster. Auto ranging with TTianuGl ovorrEdcH high spayed sampting Has data hold, 33-dot ana- log bargreph, 200 \iA low-currenl range ond continuity sounder. Fo!d-OUl stand/hanger. Measures lo 1000 VDC. 70O VAC, IDA AC/ DC, 30 megohms resistance. Batteries extra. ^22*107 S9.95r Infrared Detector Module. A ready-to-use 1^ receiver for rerrtote^controt projects. Combines detector {imiter and demodulator in a compact 3'tead package 5VDC, Wrih data #27S-137 3,49 XI (2) (3) (1) Pulsing Buzzer Extra- loud! 3 to 2B VDC *273-066 4,29 (2) "Ding -Dong"' Chime^ For doofoeil. entry alerf Requires 6 to m VDC »273-07l B.99 (3) Mml Buzzur. Efficient! Draws 7 mA at 12V0C #273-074 . . . 2.99 (1} High-Speed 12 VDC Motor. Up 10 15.200 RPM with no load AbOiJt 2' long < including shaft) «273-255 , , . 2.99 (2) LOM- Voltage Motor, For pro- jeds and solar power demos, t to 3V0C. #273-223 . . 99C MinJ Audio AmplrfFer With buift-m speaker. Use to boost computer au- dio, signaf tracing and more. Has a tiigh gain IC circuit, 'fe" head- phone jack, '/a" input jack and vol- ume control. Battery extra. ^277^008 ...T1.9S (1) 4*Conduclor Double Shield* ed Cable. 30 leet. For audio or data hookups n21Q^771 7.9S (2} 12-Foot ''Business Machine" Power Cord. #278-1261 S.99 (3) B-Ft. Version of Fig. 2. connector. »27e-l260 . . . . . 5.99 M) Binding Posis/BNC Adapter. For dependaole lest instrument hookups. *r274-7t5 S.95 {2) Binding Post to Banana Plugs. Statkable. Includes one red and one bSacM. #274-7l& .... Set 4>95 (1) Power Supply Project Case. Vented 2'/j x 4'Vfi ?« 3^4" molded box «270 267 3,99 (2) Deluxe Projecl Box. SV^ex ev^xG Vd-: Alt melal With protec- tive rubber feel »270 274. 10.79 20 diftonnt enclQsyms In stock ; tnfrared Detector Card, Detects normally invisible IR light. Fast way to confirm output from remote con- trols, infrared lEDs or laser in CD and video players. Great for sci- ence projects, tool #276-099 S.9S Portable Shortwave Antenna, Boosts recepiior) on worldband portables^ Chps to rod antenna. Wire extends up to 23 teet. Winds up on pocket-size reet for storage and travel. #278*1374 6.95 PC/XT Experimenter's Circuit Card. Premium epoxy prototyping Ijoard fits computer's XT bus con- nector Plated*through holes. lOVifiK 'fifl- Accepts D-sub at right. *f 276*1598 , 29.95 Right -Angle D*Sub 25 Female Connector. Ideal for use with card at lelt. Radio Shack has solder- type and IDC soldefless connec- tors lor computer and printer hookups. #276*1504 2.49 ft) Holder tof Type "N" Battery. p270'405 59e T€ dltiefent hGlden in stock! (2) Telescoping Antenna. U^*". SiK sections >»270-i409 2,59 f6 diffennt antennas in slock! g. m s 3 Slncft 1921 Rudio ShflGk hn been the prntre to obtain up-to-d«t» eivcirpnic paiis m wnell as quahty toolt, lost equip mem and accessories at low prices. Our nearly 70t}0 location* dri? ready to serve you— NOBODY COMPARES PfTTd Jpciif il CiJ'tt EJlinq thdta SJ-jc* Ttc*ti jnd dtJl^r^, flja.D Sflic* r, i j ri.cn nf Tinijj CQrwa'-ion MmERICM'S TECHUOLOCV STOKE' CIRCLE 7B ON FftEE INFORMATION CARD WHAT'S NEWS A review of the latest happenings in electronics Petal power? Electrical errgineers at Ihe Geor- gia Institute of Technology (Atlanta, GA), with support from the U.S. Joint Services Electronics RrDgram, have discovered that adding serra- tions shaped tike flower petals to the outer edges of satellite dishes can significantly improve their per- formance by reducing unwanted "sidelobe ' radiation— energy that is unintentionally scattered by the dishes. Reducing it minimizes the chance that antennas will interfere with each other or send signals in undesined directions, both of which could cause problems for future telecommunications satellites that will be placed much closer together in geosynchronous orbit. The edge treatment, for which Georgia Tech has applied for a pat- ent, allows designers to customize the serration design for specific ap- plications, taking into account such factors as how much gain will be lost to reduce the sidelobe levels. The optimal length for the serrations seems to be about 10 times the wavelength the dish is designed to reflect. It isn{ necessary for the pe- tals to be of uniform size, The petal-edge design has been incorporated in an outdoor compact range recently buM for the U.S. Army s Electronic Proving Grounds DR, EDWARD B. JOV. PflOFESSOR OF ELECTRICAL ENGINEERING at Georgia Tech, shows antenna dish with flower petal edges that improve the antenna's performance. at Fort Huachuca. AZ. and at least one manufacturer of compact an- tenna ranges has already adopted the technology. The edges will add I little to the manufacturing costs of dishes, and could even be retrofit- ted onto existing dishes, although such modified dishes would require alterations to the feed systems. Harder than dramonds? High-resolution x-ray measure- ments performed by scientists at Ford Motor Company (Dearborn. Ml), show that gem-quality dia- monds synthesized by scientists at GE Research and Development Center (Schenectady. NY) contain more atoms per cubic centimeter at room temperature than any other solid known to exist on earth The diamonds, which are composed al- most totally of the isotope Car- bon- 13h are of greater crystalline perfection than any found in nature, and range up to three carats. Carbon exists as two stable iso- topes: Carbon- 12 and Carbon*13. Each Carbon- 13 atom is slightly heavier than its Carbon-12 counter- part. Diamond is composed of car- bon atoms arranged in a regular lattice, with each atom at ihe same small distance from its neighbors. The regular lattice, small distance between atoms, and very strong carbon-to-carbon bond, account for diamonds unsurpassed hardness. Natural diamonds contain 99% Car- bon- 12 and only 1% of Carbon-13. while the synthesized diamonds are made of 99% Carbon- 13 and !% Carbon 12. A proprietary two-step process invented in the late 1980s by GE scientists involves, first, a low-pres- sure chemical vapor deposition technique to produce aggregates of small diamonds with the desired ISO topic composition, and second, dissolvrng and recrystallizing the ag- gregate into gem-quality diamonds weighing a carat or more. The Ford experiments showed GE RESEARCH AND DEVELOPMENT Center scientists exa mine a model of the atomic structure of a diamand syn- ihesized from 99% Carbon-13, The dia- monds, shown In the foreground, could turn out to be harder than natural dia- mond, currently the world's hardest ma- teriaL that, as Carbon-13 interaction is in- creased, the interatomic distance, or lattice constant, decreases slightly Some scientists speculate that the smaller lattice constant could make the GE diamond even harder than natural diamonds. Also revealed by the Ford experi- ments is that the GE diamond's crystal quality approaches that of I the best man-made semiconductor crystals. Because improved crystal quality translates to improved elec- tronic properties, that discovery is expected to stimulate the develop- ment of electronic devices based on dramonds. Laboratory studies have shown that synthesized gem dia- monds can be electronically '*doped" by the incorporation of small amounts of boron, which transforms it from an insulator into a semiconductor GE manufactures diamond heat sinks for the etecironics industry as well as diamond abrasives for ma- chining, grinding, sawing, and drill- tng appiicattons, R*E WHAT YOUR TOOLS SAY ABOUT YOU. "Ultimate Professional" Hots the newest family member: [he 60 NiHz Tek 224. lis as rugged, [tltableand my to useas ehe rusr of the 220 Series -arwl extended bandwidth makes it the kigical choice for computer service professionals. "Ace Troubleshooter" Hie Tek 222 is e^^thing a service scope ought to be, LighcTweight, Rugged. Fully programmable. Floatable to ±400 V. TftT3 channels, 10 MHe, Auto Setup and Auto IHgger make ie easy ti ruling tmuble-fasc. They're just 4 16 pounds. U.L certified. And start at $2450. 220 Scries handheld t>sci[loscopes-all with Teks exclusive IsolatedChanner** architecture -are the service tools the professionals use. Therms one with you written all o^'cr it. To order, contact your Tek representative or distributor. Or just <^1 Tek direct" 1-800-426-2200 Tektronix /t^sI and ffleasurement CIRCLE 92 OH FREE IN FORM An ON CARD VIDEO NEWS Whafs new in the fast-changing video industry. DAVID LACHENDRUCH m ''Use it or lose it.'' Anticipatmg the arrival of HDTV, the FCC is preparing new albcation of TV channels to permit broadcasters to simulcast in standard NTSC and HDTV during a long transitional period. The FCC has found that there will probably be enough chan- nefs in most markets to allot those extra frequencies to broadcasters who are planning to transmit in HDTV. However there *s some fear that broadcasters, hesitant be- cause of the expense of converting to HDTV, might merely sit on the extra channels. Thus, the Commis- sion s chairman, Alfred Sikes* has warned that broadcasters won't be allowed to dally and that the UHF spectrum space that broadcasters don t use after a respectable period of time could well be turned over to land mobile services. The FCC is asking a number of questions to prepare for HDTV, including how long stations should continue broadcasting in NTSC after the ar- rival of high definition. • Two4ens camcorder. One of the last holdouts against the 8mm video formal— Sharp Electronics — has come into the fofd in a big way It has introduced two camcorders With dual-lens systems. Each of the compact, palm -sized models are vir- tually two cameras in one. One lens provides a fixed -focus, wide-angle picture, the other an 8:1 zoom sys- tem. The wide-angle lens gives a 62° filed of view, and switching from §j one lens to the other provides "in* ^ stant 12:1 zoom/' according to ^ Sharp. The system provides a 5 number of special effects. It can be g used for picture -in -picture, with I both lens and CCD operating sys- o tems operating at the same lime, or ID the user can "wipe" from one lens ^ to the other. The basic model has 5 monophonic sound and a mono- chrome viewfinder while the higher priced model has stereo audio and a 6 color LCD viewer With Sharp s addition of 8mm (it will continue to offer VHS camcor- ders as well)* only JVC— the inven- tor of VHS — has no involvement with 8mm, among all major cam- corder makers. Even Matsushita Electric, which doesn't offer 8mm camcorders under its own brands CRanasonic. Quasar and NationaD. manufactures 8mm camcorders on a private-label basis of other brands, e Home multimedia. Nobody has really defined the word "multi' media. " which is largely used to de* scribe CD'ROM computer prod- ucts to which interactive video has been added. Those offering non- computer items with similar at- tributes have generally avoided the word. The question for the future is whether multimedia will enter the home as a computer or as an attach- ment for the common TV set. Al- though there are many approaches to multimedia via the computer so far only two systems have been in- troduced that use the family TV. Those are Commodore's CDTV, which is based on the Amiga com- puter but has no keyboard, and Phi- lips" CD-I. launched with great fanfare (Rad ia-Electronics, Feb- ruary 1992) reportedly is selling well. Philips recently announced agreement with Motion Picture Ex- perts Gnoup (MPEG), a standards- setting body, on a standard to add full-motion video to CD-I. All CD-I players have a port for the addition of a chip to provide full-motion, fuli- screen video. Philips promises the plug-in chip by mid-year While Philips is attempting to ap- peal to the entire family with its CD-I programmtng— includmg children's activities, adult games, and refer- ence materials — Commodore says it will begin next year to offer spe- cial-interest interactive packages, including MIDI (musical instrument digital interface) selections for au- dio enthusiasts and titling and cap- tioning software for videomakers. Commodore also plans to bridge the gap between TV-based and computer-based multimedia by of- fering a CDTV drive to the 750.000 Amiga computer users in the U.S. • Full HDTV schedule. High definition broadcasting is now on a regular schedule in Japan, the satel- lite-deNverBd Hi Vision signal being transmitted for eight hours daily, al- though the bnDadcasts are still billed as "experimentaL" So-called '^reg- ular" HDTV broadcasting is still three years off. Japan s analog HDTV system has been under de- velopment for more than 20 years. TV sets to receive and display the broadcasts in full HDTV still cost about 330.000, and HDTV VCR's are around $115,000. although costs will come down. Already some private broadcasters in Japan Cas opposed to the public NHK net- work, which developed Ht-Vision) are calling the Japanese system an "intenm" measure until a truly dig* itai system is developed. • Bigger S VHS push. Although more than 20% of all VCR's sold in Japan are in the Super VHS format, the proportion in the U.S. continues to hover arDund 2%, Panasonic now plans a major campaign around S-VHS. with lower pnces^ — a strategy al- ready being followed by JVC. which is now shipping an S-VHS deck car- rying a "nationally advertised price of $799." about $500 less than the cheapest model last year: Although Panasonic "s pricing hadn't been re* vealed at our press time, it is ex- pected to be at least in line with JVC's, in addition. Panasonic will bring S-VHS into more complete VHS compatibility by making its en- tire VHS line S-VHS "playback compatible" — meaning that its standard VHS decks will be able to play S-VHS tapes as well as stan- dard VHS (although with only stan- dard VHS resolution). R-E Afford Ability In a dc power supply. Now, put a dependable, 30-watt dc powor supply on your bench for just 5300^: YoitH get the low noiso your work fieniands (200 pV nm). ConsUint-voltage or constant- cunrnl o[>eration. And built-in reliability easured by conservative design nuugiJis and rigorous cnvironntenial testing. Outstanding %'alue in a dc power supply. It's jiLst one in a full line of basic instiiinients developed l>y I IP (0 give you miconiprO' niising performance at an affordai>le price. , To order, caU HP DIRECT; l-800-452^844,* ExtTVV13, Well slup your order the day ifs received. Inslrunients come with a sLxty-day, money^back guarante6._ i\ll you need is a - - ^ ■ ~~^J company purdmse M order or credit card. powef suppliet mm E3&11A E36iaA a O Range 1 W tSOA m0.60A 15V. 2A 35V, 0.B5A 120V, 0.2SA l^Ad Of line r«9uta(tion Hippfe pnd noise |10Hz-10MHz] There is a better way. HEWLETT PACKARD * U.S. list pncu. ^ in Conada trail 1 W3S7=^7,J^cpt 442. to P 23 o m 8 3 ■O lfJ2 Ht'wLftl-Packanl Cn. 'tMbiJiliHyi&ml CIRCLE 192 ON FHEE INFORMAUON CARD Ensure Serious ure in that Fkituie with tiie Best Educational It'aining Available. SEND FOR YOUR CIE HOME STUDY COURSE CATALOG AND RECEIVE A FREE 24 PAGE CIE ELECTROMCS SYMBOL HAISJOBOOKI rnciucfes hundreds of ttie mo Jt frequently used erectfonic symbori. Published by CIE exclusively far our studenU and diumni. Voun free when you re()uest a OE Course CitaJog L -f you want to learn about electron- ics, and earn a good income with that knowledge then CIE Fs your best educatronai value. CIE's repuiacton as the world leader in home study electron res Is based solely on the success of our graduates. And we've earned that reputation wiih an unconditional commitment to provide our students with the very best electronics training. Just ask any of the ISO.OOO'plus graduates of the Cleveland Institute of Electronics who are working rn high-paying positions with aerospace, computer medical, automotive and communi' cation firms throughout the world. They'll tell you success didn t come easy.. .but, it did come.... thanks to CJE. And today, a career in elec- tro nJcs offers more opportunities and greater rewards than ever before. CfE's COMMrTTED TO BEING THE BEST.,..IN ONE AREA.. ..ELECTRONICS. CIE isn t another be-everything-to- everybody school. We teach only one subject and we believe we're the best at what we do. Also, CJE is accredited by the National Home Study CourrtiL And with more than a 1,000 gradu- ates each year we're the largest home study school specraliztrrg exclusively in electronics. CIE has been training career-minded students like yourself for nearly 60 years and we're the best at our subject ELECTRONICS BECAUSE irS THE ONLY SUBJECT WE TEACH! CrE PROVIDES YOU WITH A LEARNING /WETHOD SO GOOD, irS PATENTED. ClE's Auto-programmed lessons arc a proven learning method for building valuable electronics career skills. Each lesson is designed to take you step-by- step and principle-by- principle. And while all CJE lessons are designed for independent study, CIE's instructors are personally available to assist you with just a toll- free call. The result is practical training,., the kind of experi- ence you can put to work in today's marketplace. LEARN BY DOING...WrTH STATE-OF- THE-ART FACILmES AND EQUIPMENT, In 1969, CIE pioneered the first Electronics La bora* tory course and in 1 984. the Hrst Mirco processor Latxiracory course. To day^ no other home study school can match CIE s state^af-the-art equip- ment and training. And all your laboratory equipment, books, and lessorrs are included in your tuition. It's all yours to use while you study at homo and for on 'the *job after graduation, PERSONAUZED TRAINING., ..TO MATCH YOUR BACKGROUND. While some of our students have a working knowledge of electronics others are just starting out. That s why we've 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 TRAINING? • 1 50,000 successful graduates from every country around the wortd, ■ Only CJE rewards you for fast study, CIE offers an Associate Degree program based on aaual study time used. The faster you complete your degree the less your overall tuition. ■ States f'the-art laboratory equipment is yours to keep and it comes assembled, ready for hands-on experiments. ■ Approved for educational benefits under the G.I. Sill for veterans and other eligible persons. ■ Upon graduation, CIE offers free preparation to pass the Ceitrfied Electronics Technician Exams. core lessons applicable to ail areas of electronics. And every CIE course you take earns you credit towards comple- tiorr of your Associate in Applied Science Degree. So you can work toward your degree in stages or as fast as you wish. In fact, CIE Is the only school that actually rewards you for fast study, which can save you thousands of dollars, SEND TODAY FOR YOUR CIE COURSE CATALOG AND WE LL SEND YOU A FREE 24 PAGE CIE ELECTRONICS SYMBOL HANDBOOK! □ YES! I 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.) ^^^^ AOdresi:. Oiy:_ ^Staie: Ztp: .Age: Phof>e No. I J Check tXM for GJ Buitetm Benefits „ Veteran Active Duly CLEVELAND INSTITUTE OF ELECTRONICS 1776 East l7mSkeel Cfeveland. Ohio 44114 t2l6) 781-94CX) A^tAuof one ASK R E Write to A^k F? F RadiO'Efectron'r^-. 500-B BhCounty Blvd, Farmingdale. NY 11735 VIDEO FADER [*m interested in learning how to design video hardware and I have been working on a circuit that would cause a video image to fade as I turn a potentiometer IVe tried several ideas but keep running up against the same problem. As I cause the signal to fade, it always starts to mess up horizontally and vertically be- fore the image disappears com- pletely. Tm not asking you to design the circuit for me, but I sure could use some advice. Do you have any idea what Tm doing wrong?— D. Koetting, St. Louis, MO It's always a pleasure to answer a letter from someone who Lfnder- stands that the only way to learn is to make mistakes and work out the answers with a mrnimum of help and a maximum of brainwork. I've studied your schematics and you've been making the same mis- take each time. Each design you've done assumes thaE the video signal is similar to audio in that all the infor- mation contained in the signal is spread equally throughout the sig- nal's entire voltage range. The video signal is extremely complex and dif- ferent parts of it are reserved for different purposes. A typical line of video is shown in Fig. I , Notice that the line is divided horizontally be- tween the picture infomnation (want to fade), and the control information (want to leave aloneX The only thing wrong with the de- signs you sent me is that they all treat the two parts of the video sig- nal equally. By dropping the voltage level of the entire line of video, you're cutting the level of the control information in the honzontal interval as well. For your designs to work properly, your circuit must dis- tinguish electronically between the picture and the control information in the horizontal interval. This is the same problem that every television has and. as you would expect, there are one*chip solutions to the problem. National Semiconductor and other manufac- turers have a range of chips avail- able that can separate picture and sync. If you want to build something of your own to handle this problem, the answer will become evident when you realize that in a standard NTSC signal CI volt peak-to-peak), the picture data lives above 300 mil- livolts and the sync information lives below that. You didn't ask for a spe* cific design, but remember that in 5- volt TTL land, the picture informa- tion will be seen as a high and sync will be seen as a low. Once you vvork out that part of the pfoblem. you have to use the sync signal to gate your fade circuit. Reducing the picture to 300 millr* volts will make it disappear com* pletely, and passing the whole signal during the sync interval will steady the image as it fades away on the screen. EGA^VGA ADAPTER I have an AT clone and re- cently I upgraded my video card from EGA to VGA but I am still saving to buy myself an analog VGA monitor. The problem Vm having at the moment is that my old EGA monitor has a nine-pin connector and the VGA card has 1 6 12 I 0 RG, 1 — THE VIDEO SIGNAL Is extremely complex and different parts of It are re$erve/ Courses from Heath kit Educational Systems, accredited and licensed as a premier electron- ics educator. s/ Continuing Education Units (CEUs) awanded on successful completion of most Healh courses, _ I To receive your FREE Heath . Catalog, fill in your name and I address t>€!ow and mail TODAY! I To: Heaili Company I Dept. 020-150 [ Benton Haft>or, U\ 49022 1 Name ' Address ! City . I State/Zip CmCLE &6 OM FREE INFORMATION CARD TABLE 2 PINOUTS OF THE NINE- TO FIFTEEN-PJN IBM VIDEO ADAPTER LETTERS Write to Letters, Radio-Eleatrvnics, 500-B BhCounty Blvd.. Farniuigud^^ A REAL SOAP OPERA Radio-Electronics readers might be interested to know that radio musical comedy is still alive and well in the 1990's, 2BS Founda- tion has produced "Dish pan Fan- tasy." a modern comic opera that is available to public radio stations as two half-hour programs. The format might be reminiscent of the past, but the plot and production meth- ods are strictly contemporary. The story line blends bits of feminism with fantasy comedy love, and self- discovery. The music ranges from classical to rock'nVolL from 50 "s cocktail lounge songs to Afncan drums and whistles. The voices of two opera singers were used to create the seven characters in the opera. By running the singers voices through a processor, the pfD- ducer Tim Clark, was able to create a cartoon-like quality. Using samplers and synthesizers, sound effects and environmental back- ground noises were added. The "Fi- nale" music-writing program was used for composing the operB. and the "Performer" program was used for the preliminary 'rough mix that allowed the singers to hear their parts with full orchestration. After the voices were recorded on a multi- track. Clark went back and added the music that was in the computer in the Performer program. Besides simplifying production, computer technology offered one big plus; Listeners can hear every word. Clark was able to rearrange the vo* cats and instrumentation so that the singers' words were always cleariy understood. Check local public ra- dio programming schedules for broadcast times of "Dishpan Fan- tasy/' KATHY GRONAU ZBS Foundation If "Dishpan Fantasy'* fsn't being broadcast in your listening area, you can order it on a 72-minute audio cassette for $12,95 directly from ZBS Foundation, RR#1 Box 1201, Ft. Edward. NY 12828-9713. Thetr phone number is 800-662-3345 — Editor ONE READER S OPINION I'm writing to let you know that you*fB doing a grBBt job. I work as an electrical engineer in the auto- motive field at a major R&D outfit during the day. and work towards my masters in E.E. at night. My job requires that I slay on the leading edge of technology and be informed on the latest techniques, apphca- tions. and discoveries. Radio- Electronics has been a great help in meeting those requirements, I can't emphasize enough that edu- cation is a priority for success and must be a lifetime commitment, I've always preached to other elec- tronics students that Radio-Elec- tronics is an excellent source of information. 1 love to study the ■"Build This" projects, admiring some of the designs — and catching some of the errors. The technology articles provide an excellent review. The vanous departments keep get- ting better, and 1 hate it when I don't have time to read them all. One suggestion for improve- ment: I'd like lo see a section in Radio-Electronics devoted to testing your electronic skills. Per- haps it could be a one-page test, covering a different topic each month, that readers could take to quiz themselves. Taking such tests really keeps you on your toes. Keep up the good work? J. KEITH DAVIS San Antonio, TX ADC FOR YOUR PC IMPROVEMENTS The surface temperature prube in "Expenmentmg with ADC for your PC (Radio-Electronics. Janu- ary 1992) should not have its handle filled with epoxy or silicone, as that will increase heat transfer between the sensor and the handle, thus in- creasing response time and de- creasing accuracy. The top of the TO 92 case should also be filed flat to increase contact area and heat transfer between the sensor and the measured surface. At the low- temperature data- gathering point, be sure not to rec- ord the voltage until the ice cube is wet from its own melting. An ice cube just out of a freezer could have a temperature well below C'C. At the high-temperature data- gathering point, the probe should not be immersed if it's to be used as a surface probe. Place it against an outer flat side of the container of boiling water, just below the water level. Bnng the water to a rolling boil reduce the heat slowly and rec- ord the voltage just as active bubble production ceases. A rolling boil can be more than rc above the true boiling point— which is also greatly affected by the barometric pnsssure. Pure water will boil at less than 9S'^C in Denver un- der the influence of a low pressure system, and at more than lOI^C at sea level under the influence of a high^pressure system. The current uncorrected baro- metric pressure can be obtained from your nearest airport or weather bureau. For every 0/1 inch of mercu- ry above or below 29.92 inches, adding or subtracting 0.1 *C from lOO^C will be quite close. For immersion probe con- st njction. on the other hand, ther- mal isolation of the sensor from the handle is of little concern, but moisture proofing is important. For the low- temperature point, immerse the probe in a constantly stirred slur- ry of chipped ice and water using + 0.3X instead of O.OX as the temperature. At the boiling point, don't pour the water into another container. It will lose several de- grees in the process. Immerse the probe to just above the bottom of the container, making temperature corrections and voltage recordings as outlined above. DAN A NIEMl Cwinn, Ml SCRAMBLER/DESCRAIVIBLER REQUEST It has been several years since my service training in electronics. As a matter of fact, my education was very complete — on tubes, that is. I've just recently regained my in- terest in electronics as a hobby for my golden Csilicon?) years. After making a bunch of doo-dads directly from simple schematics. 1 would like to get back into designing my own circuitry as I did in days of yore. In the meantime, while my knowh edge is getting modernized, t would greatly appreciate plans for a simple solid-state scrambler/descrambler. The parameters could be very lim- ited, since it only has to be variable to give four or five "channels" and an audio band (even just the fre- quencies of the human voice). It's hard to believe the changes that have come to pass. Picking up my first subscription copy since dnDpping out years ago is like start- ing to learn a foreign language that your distant relative spoke in your youth. In any case, it is satisfying to see that the quality of Radio-Elec- tronics has not suffered. LEN BOULTER Prince Rupert. B.C. Canada Keep reading— we 're working on just such a project! — Editor n-E esYou Frequenc Counter Give Hon tnnnnnn lUUUUUU B+K PRECISION frequency counters are conservatively rated and designed for accuracy* Before you buy a counter^ compare specs and ask auesHons.. . Does high-input sensiHvily come at the expense of false readings with no input? fs time base drift specified per year, orjust per month? Fnom 0' to 50" C or only at room temperature? B+K precision's rugged, lab-grade counters have guoranteed specs, TheyH perform OS promised, every time You con count on B + K I 1 .3GHz 8-dig It 1 75 MHz 8-dig it M u Itif u n cti on C o u n ter U n i ve r s a I C o u nte r Frequency, period, periodaverage, ■ Frec^uency,period,poriodaverage, end totalize functions ■ 1.0 PPM TCXO time base ■ 10 mV nms max. sensitivity ■ Optional accessory antenna ■ 0.1 H z ma x. reso I u f io n ■ Remote start-stop Model 1856 S495.00 totolizei frequency ratio, and time-intervol function ■ lOPPMtimebose ■ 20 mV rms max. sensitivity ■ Optf on a I a ccesso ry a nte n n o ■ 0 J Hz max- resolution Model 1823 $395.00 For detailed specifications on the complete line of B+K PRECISION frequency counters or immediate delivery, contact your local distributor or B+K PRECISION. MAXT^ inmRNAnoNAL corp. J ® Dome Stic and I n temational S ale s 8470 W. Cortland St. , Chicago. IL B0635 312'BB9-1448 * FAX: 312 794-9740 CmCLE 77 ON FREE mPORMATlOtJ CARD NO COMPLICATED ELECTRONICS. NO EXPENSIVE INSTRUMENTS: Home study couise shows you how to make gooil money in VCR repair. An amazing fact: you can do more than four out of five VCR repairs with ordinary tools and basic fix-it proce- dures. Our home study pro- gram shows you how Learn all of the systems, mechanisms, and parts of almost all brands of VCRs. With no expensive instru- ments. No complicated elec- tronics. iVo fancy workshop. The step-by-step texts and close personal attention from your instructor make learning easy. Texts, course materials, and tool kit are sent to your home. Graduate ready to make up to $50.00 or more per hour in your own spare- time or full-time business. Send today for your free career booklet. Or call 800-223-4542 Name Address . City _ State. - ^ip - The School of VCR Repair 2245 Perimeter Park, Dept.VC342 .Atlanta, Georgia 30341 I I t15 I E I tu 6 -o m er 16 IF YOU MAtNTAIN. REPAIR OR Up- grade electronic equipment you should become a Certified Elec- tronics Technician (CET). Heres how you can become someone special On behalf of its more than 32,000 Certified Technicians. Ernie Curtis, CET Chairman of the Inlemational Society of Cer- tified Electronics Technicians, has declared Tliesday. March 10, 1992. "Electronics Technicians Day." "The electronics technician," stated Curtis, "is responsible for keeping today's electronics* dependent society operating. Without this highly-skilled and specially- trained corps of elec- tronics technicians, break- downs in modern complex elec- tronics would quickly bring our world to a sparking halt. Our intention," Curtis continues. MARCH LARRY STECKLER, EHF/CET, Editor-in-Chief "is to focus international recog- nition on the high standards of performance and excellence maintained by professional electronics technicians." Over 100 ISCET Cert Ifical ion Test Administrators have volun- teered to give tests during the week of March 8 through 14, 1992 to honor Electronics Tfech* nicians Day. The complete list of all of these test sites is pub- lished in the pages that follow this article. In 1991. the 30.000th CET Robert Bruce Bottoms, CET was an ISCET member who used T-Day 1991 to upgrade from Associate to Jour- neyman. Bottoms, an employee of United Parcel Service, at- tended the 1991 ISCET conven- tion in Reno, Nevada, and addressed an enthusiastic au- dience about his desire lo repre- sent a new generation of CET s. What is ISCET? As the proud elect ronlcs tech- nicians division of the National AT THE tSCET CONVENTION, the current iSCET chairman, Ernie Curtis, CET (lett) accepts the gavel from outgoing chairman^ Leonard Bowdre, GET Electronics Sales & Service Dealers Association (NESDA), ISCET was founded in 1970 by a committee of Certified Elec- tronics Technicians, whose main purpose was to foster re- spect and admiration for their profession. By maintaining rigorous standards in its cer- tification program, ISCET is able lo separate the highly sltill- ed and knowledgeable techni- cians from those with less experience. ISCETs main func- tions include direction and ad- ministration of the CET pro- gram, the national apprentice and training program, the tech- nical information training and upgrading programs, and the serviceability programs. The CET program was de- signed to measure the degree of theoretical knowledge and tech- nical proficiency of practicing technicians. A technician with a CET certificate is thought of in the industry as one who pos- sesses the training and exper- tise necessaiy^ to perform his job with professional competence. Since its inception, the CET program has corjtinued to gai[i acceptance by technicians, manufacturers, and consum- ers. Many organizations en- courage, and often require, their technical employees to be certified by ISCET, Itetmician skills Jusi keeping up with the changes that seem to occur dai- ly in new equipment is a full- time task. To be able to service the latest electronics equipment with its new circuitry, new com- ponents, and new principles is a difficult challenge. Todays electronics technicians must constantly learn, constantly aq- ulre new theoretical and prac- tical skills, and constantly develop new techniques. They must become familiar with new 1 0 - ELECTRONICS ■ TECHNICIANS DAY kinds of test equipment and new servicing techniques to re- pair the latest electronics engi- neering mar\'els. Perhaps this was best summed up by Leonard Bowdre, CEX ISCETs Immedi- ate Past Chairman, when lie said, "I marvel at the exponen- tial changes in electronics since my introduction to it in 1946, The new techniques, devices, and technolog>^ that have ap- peared in the last two y^ars alone are mind-boggling. With what todays technicans must know. I think they must be the most qualified, most under* paid, and the least recognized in the world's work force." The GET exam To become certified by ISCET the electronics technician must pass both a 75-question Associ- ate-level GET test, and a 75- question Journeyman-level test. To pass, the candidate must score a grade of 75% or better An electronics techni* cian or student with less than four years of experience may ap- ply for the Associate-level exam only, which covers the foDowing subjects: • Basic Mathematics • DC Circuits • AC Circuits • Transistors and Semiconduc- tors • Electronic Components • Instruments • Tests and Measurements • Troubleshooting and Net- work Analysis A fully certified technician must have four or more years of education or experience in elec- tronics and must pass, in addi- tion to the Associate-level test, one or more of the Journeyman options available in specialized fields of electronics. The Jour- neyman options that are avail- able are: • Consumer — Subjects covered include antennas and trans- mission lines, digital and linear circtjits in consumer products, TV and VCR servicing prob- lems, and the use of test equip- ment. • Industrial^ — Subjects include transducers, switches, power factor, differential amplifiers, closed-loop feedback, basic log- ic circuits and functions, ele- ments of numeric control, th)fratrons. and SCR controls, • Communications — This test covers tw^o^way radio trans- ceiver theor>' and servicing, re- ceivers, transmitters, baste communications theor}^ devia- tion sensitivity, quieting, and i rou bleshoo t i ng, • FCC Legal— This is a 25- question optional exam cover- ing FCC regulations. Applicants who take the associate exam, the Communication option, and the FCC Legal exams will receive a general radio-tele- phone license, • Computer — This test covers operation of computer systems with basic emphasis on hard- ware. Subjects covered include basic arithmetic and logic oper- ations, computer organisation, input and output equipment, and memory^ and storage. Some knowledge of software and pro- gramming is required, and the ability to explain troubleshoot- ing procedure is also required. • Audio — Products covered In this option include turntables, tape decks, compact discs* and 1 J* e> 9- o TRAINING NEVER STOPS for eteclronic technicians. Here Ernie CurUs, CET and other ISCET Members learn about the latest deveiopments In digital electronics. 17 radios. The exam consists of both digital and analog sec- tlons» ampHfiers and sound quality, system set-up, speaker installation, and troublcshooi- ing audio systems, • Medical — The priorities of this option are electrical safely and accuracy of calibration for electromedical instruments. The technician must be familiar with the basic vocabulary of medical instrumentation, tele- metry, measurements, and dif- ferential and operational ampli- fier applications, • Radar— -A general knowledge of both pulsed and continuous- wave radar is necessary to take this Journeyman option. The test covers transmitters and re- ceivers. CRT dtsplay systems and their power supplies, and antennas, transmission lines and their characteristics. • Video — ^The rapidly growing field of video is covered by this exam. The technician needs to know NTSC standards, video basics, test signals, and the op- eration of both the electronic and mechanical systems in VCR's. Also covered are 8mm video, camcorders, cameras and monitors, and the micro- processors used in video prod- ucts Fees and difficulty The fee for the CET exam Is $25.00, which includes both the Associate exam and anyone Journeyman option, if taken in one sitting. If the Journeyman option is taken separately from the Associate exam, each test is S25.00. Each additional Jour- neyman option is S25.00, If you fail any portion, the first retake is free, after a 60-day waiting period. The fee for any addi- tional retake is $12,50. If you choose to take the FCC Legal exam after you have suc- cessfully completed the Com- munications op t ion ♦ there is an additional fee of SIO.OO. Don't underestimate the difficulty of the CET exam. Every year only 30% of those who take a CEt test pass — it is not an easy test! The best way to prepare for this exam is to study diligently Tab Books publishes The CET Study Guide by Sam Wilson, which will help you prepare for both tests. ISCETalso has addi- tional study guides available for a nominal fee* If after reading this article you*re interested in taking the CET exam and joining the grow- ing ranks of Certified Elec- tronics Technicians, contact any one of ISCETs volunteer test administrators listed in this article for details. The exams are scheduled to be given during the week of March 8 through 14. 1992, For any addi- tional information you might need, contact ISCET at 2708 West Berry St., Fort Worth, TX 76109: phone 1-817-921-9101, Join the professionals \buYe already competent in electronics or you wouldn't be reading this magazine and this article. You need to gain the rec- ognition you desene. To do so, take the CET challenge and join 32,000 other electronics profcs- sionals- Become a CET. It*s worth the effort and you deserve the recognition, R-E ISCET CERTIRED ADMINISTRATORS FOR CET EXAM I 9 CO 18 David L. Bryiin. CET Alataamn Avt^. 4 Tocti Cod. PO Box 1209 Oiaik, Al 36360 (205} 774-5113 Davtd McCam GET 64 StiKflo iirw Loxtoy, AL 365St (205) 343 6200 1218 Sourh 2m St anrtfignam. AL 3S205 ^205) 933-6536 fbcky G ReawiH CET Shoals Comm Ccti Mii9d« Bhoata, AL 35662 (205) 3S1-2813 R. T Van idBTstBi* , CET Soitfnnil State "fect^ Coioge MoWft, AL3SG0& (205> 947^1 AkQon 4 Ft«*i*r, CET unto Rodi. AR 72209 (5on ses-Tooo Oemn ft Blum, CtT Phoenut Inst, ol Tech. 3555 Univorcfty Or, PhoeniK. AZ 85034 (602) 244-8tn Frank Grab^. CTT 1704 E ClarofTKml Ph06m. AZ 06013 (502J 270-3701 H.*l Raine, CET 4631 E. B^h SL Tucson, AZ857U (eozi eai-e7G4 Russe^J Scafpdii. CET 10S2> W. Dos&ert ForsL Crte. Sun City, AZ 85351 (602^ S72'3e54 S^oo AJonso CaM. Bu«ine$9 InftL 35S0Johfis«fiAivi», El UotHB. CA ai731 IS16) 444-7770 Btfly J Edmortt^ CET i3Tl i6tri Sr Baywod, OA 93402 teOS) 543^2700 EH 7772 HoHSfd Barctich, CET The Auio Sfidciaiit S^j£teQ«yCA 01604 (916» 76^3009 Jotm V. Craio- CET S31 W. Huenenw Rd Oxrurtl. CA 93033 (005^ 0e2-&22B Msx B. Frefl Cahtsmia Wed fa^tf 2100 Pe.iixxJy Rd Vacavitld. CA 95696^4000 r707| 448-6841 Exi 335S Robert A, Johnsofin CET 4600 AsHo F^ . . #313 Bakersheld, CA 93313 mS] 835-9225 ITT Technical In^tiusis 1530 W CarrBiwi Ave W. C^na, C A 91706 (SIB) 96&a63l David htafsoo, CET California Yotrth Authority PO Box 1245 Raso d© Robie^. CA 93447*1245 (805) 238-4040 Del 426 W^chae^ R, Milter. CET CaJikimia Mens Colony-Wfrst PO Sox eiOS-EducaikJfi Dcfpl. Ski. CA 93403-0006 (80SJ 543-2700 Ejrt 7143 Peter JL Motwo, CET nr le&^rac^ Insiitute 630 E. Brier Dt, #150 San Beniafi^. CA 92406 f7l4) 889-3800 Kevin J. Prtoe, GET NEC San Bamwtto. CA d2«oa t7t4) t Or Konrwlh L, Wilson, CET San D«9oCrty Cofiege 13t3-i2lh Ava. Ban Dmqa. CA ^01 ^6191 230-2601 Don WJnchol, CET M & 0 EledronM;:^ PO Boic ^23 Smarhflllo. CA 95977 {fltOj ^^-2477 Jotin F McMulhin, CET DonvQf jnsl. o( Tech, Inc. 73S0RBfoadwQy Dtfnv«f. CO 80221 (303} 426^1808 AJbfin Mbses, CET PO Boa 188 Cheft*^, OE 19930 OOSf 571 5402 GflOtQ« W- Shifitet C^ WdMd, GO 009T1 mm 3924000 John R Stacknouss, CET ITT 2121 Scwai Bi«*n«A Aytora CO 80014 4303) m^im Pwiz Shams SooJheffi Inst, Tech. 10600 Kals^ Awe. Anaheim, CA 92S04 (714) 520-5552 Fioancft J SriMJfi. CET Ed. Dept Calif. Mens C^f1y PO Bon SiOi San Obispo. CA 93409-0003 Corlox, CO 61321 IB05) 772-2009 (303J 5e5'8457 Anthcjny R VliWez,CET t9l9 Rottino Hm Rd. Darnell Sh^, CET Conn.. School of Elodrorucs 586 Ella Qrassa BM U(m Hiiv(?n. CT 06519 (203) 624 2121 Wiltjam S. Brooks, CET 7112 N. Habana Aw. Tampa, FL 33614-1365 (813) mi 793 Ed¥<5ifd Guary, CET Eddy^ HadKi & TV SorvKs TiiO NE 4ih A«, a Uuler^. a 33304 (305) 763-2964 ROh^A-KaniieHXCET Nee Bayder CoteQ« 7955 NW ta Si. MLamL FL 33126 (306} 477-0251 Kafi A. hlitfitor. CET 13S50KM CdwOc jKknrHOe. FL 32224-1143 {904)633«43 Daniel B. Muntfy, C€T Norman s Electronics 36S3 Oaimxifil Rd. N£ Atlanta. GA 30341 (404| 45^S057 ianws Pfeek, CET Panasonic 4245 E Int^aCtonal SIvd. Norcfoss. GA 30003 (404) 7t7^5fl W.R.Ftooka, CET ShiJoti Rd RL6 Box 1S1 Amenojs, GA 3170^ (912) 928-0283 EjX 26 Ebkn Shefjard. CET eioomfieid TV s«- 24S1 Rocky Onic Rd . Maoon, GA 31206 (9121 788-5281 James P. Van SanL C£T PicfcansTech. 240 eumt Itouitain Bd. JaspetGA 30143 (404) e92-3iU John Simn Bcttonfs. CET b ITT Tedmcal InsUbn^ Lewis Clark St oolegi 2600 Lake Luatn Dr , #140 8ti An^M 6th SL Uafdand, FL 327S1 L««^$ion. ID 83501 (407) 660-2900 (208} 799-2^ Phillip G Stephens Matsushita Reg. Tech. Conior 6550 Kateda Ave. Cypr^, CA 90G30 (7t4| 695-7435 John E DftPiit™ CET Conn. School of ElocrrorHCs 506 BUt Grosso Blvd N«w HtNon, CT 0^19 (203) 624^212t JUL VKadomoros. CET ITT Technical Irtstituie 5225 M(jnionai Highway Tampa. FL 33634*7350 (813) £65-2244 Roy Oiastain, CET N.e.Tt. 197 N. Box 65 Oarfee^lo. GA 30523-0065 (404)754-7731 ExL334 Douglas E. Minter. CET AinerKan CoQ«g& of Toch 1300 W. 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As you aetuiilly build your tmn software application, you doekjp hiindson experience widi Windows' eas\'4(>use fe;itufes —inchidng gnipliics, memof)* rnanagement, multitasking, tLita exch:mge, and more! Sr^. images, icons, and ^1 the other Windows features >ou need to build higJv p<:rform:ince .s^jfiware tliat meets loday*s conifK'Utive basiness needs. Send for your FREE Ml citalog today! Discover how Mil can give j'ou die a^mputer know-how }'ou need ftjr sat t cess. If the coupon b missing, wrire to XIU SebcxiLs. McCiraw-niJi Contintiing Kdne;nion Center, *i40l Cx)nnecticut Avenue. NW . Wx^hington. IX: 2m)8. SEND COUPON TODAY FOR FREE NRl CATALOG!^ SS5 W \tt.t in\% -| J il I < )t i n lit] 3 i'_ _Satc 5415-032 i c 22 George Sopod^o. GET The Radio TV Lab SS31 W tiving Park Chicago, tL 60634 {mi 545-3622 Rtti K. Taa CET 915 Augusta St Oak FVk. tL 603CE'167B pl2» 048-6327 Frai* Toskey. CET FJ. leskef Entefpnscs 3094 UfaWtte Rd. tndBnapofci. IN 46222 (317) t26-2€3§ Leonard E. Btrnm. crr 125 S€ Thoffitoo Awe. DdS Moires. lA 50915 (515) 964^64S4 James E. Bo^ CET Wsstom Uu Tftch. Comm. Coll. 4S47 Slone Avo, Sioux City, I A 51102 [712} 274*6279 Oonnm CuslOf, CET West la. Tech. Connfii. College PO Box 263-4647 Slone Ave SiouK Cfly, [A 51 TOE 0265 (712) 274'6279 Michad^ L. Baughman. CET KS Diy Aroa Tech 2220 N 59th $L Kansas Oty, KS 66104 (913) 334 1000 E*l 48 Stanlcry Dwtl. CET »«:K Aiea \tocal Ttch PO Bon 507, VWe^ Canipus O Be^ KS 67420 1913) 738-2279 Qt aw, Ko. CET 550NJ=burTTioiv HyaasJm. MD 20781 (301) 664-5750 Earl TicWefi CET Rets. Tech. Tmg, Conter 1520 S. Cetof^Avo. Battimore. MD 2\Z27 (301) 644-840O Rotierl A. Ciuleltt. CET 444 Faiimoiint St Fflchburg, MA 01420 (S08) 834-2052 Frar* Sena. CET Serra 5 TV V4d©o 1666 Massadiusetts Avq Cambnd^, MA 02138 (617) 452-2667 Bob Beiers^ CET Vt^^hlanaw Comfn. CoiOQO 4800 E Itm flfl^r Oe Ann ArtKX Ml 48106 f3!3| S73-3316 Joihn P. BoinSv ^ET St Clair Dty Cmn. 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CET East Okla Couf^y Tech 4601 U Choctaw Rd Choca* OK 73020 (405) :30-959l Donald Haag. CET RR 3. Box 92 Watertown. $D 5720t (605) 886-8932 Oiailes Daughorty. CET Eiec^oniC S£!rvtco Ccfftter 166 Fnl Si. Ht Omland. TN 37311 (615) 472-0359 Ross HuteheiMn. CET 781 lion Wbrkers Rd. Oaikswae. T(^ 37043-7911 (615} 362^9440 Herman Pstnck 371S Lamar Aw Memphis. TN 38118 (9011 362*5368 FtonaJd R RackJoy. CET Tefui Inst of ElQCtfomCs 3203 Tajew&ll Pikq Knojmlto. JU 37919-2530 (615) 688 9422 Wtliam S. Wamm. CET/CSM W^rfen s Audio- Video Service 2540 Sutherland Avo. KnoxvjJiB, TN 37010 (615) 546*1121 EariW.Hirtos.CET Star Rl. 1 BOK 1-A 1710 Lamat Swe««*«ef. TX 79556 (915) 235-1849 Larry GasslQ^ CET 37t>6 C ham be i i bi gg Dukjtfi UN S5811 (216) 722*9:^ St0u^ M BmmMcj, CET Southern Techneal allege 2305 Lakei^ Or. Jackson. MS 39208 (601) 932-7B09 Mar^ a. OermyJr.CET Aixfe>-VWeo Service 1405 Corinne St. HaltiestHirg. MS 39401 (601) 545-7808 Lloyd a. Oida, CET 301^ St. East NO 58076 f701) 2S2-&t30 ^ 220 LMTcnceM Oelonaa. CET Na&onai Educatsn Center 1860 Manm Rd MoQadorc, OH 44260 <218) 628 3tl5 Eil 19 AC Fatoone, CET Falcon Electiorncs. Inc. 3266 Kent Rd. SlO*, OH 44224 (218) 668-2451 MMi Conm Coie^t Box 370-1300 CoMy C^ REStGN 071231 X iS4.95 RMBsmm St9.9S How the Club Works VOUR BENEnrS; \'tm pet } - ^ ^ r > r ; . . , ; . , and tuDdJinf «1ieQ yoli jmn. Yofi Lcqp oa uv;n| v^iih di^woun^v ol up 5 time thcnafttr. BONUS BOOKS: St^nini immcduidj , ytw wili be cttgibic for tiur Bmus Booi. Plan, wiih saving* of up ii> SO^ t>f\ puhJjjJien' price*. IRONCLAD NO-RLSK GUARANTEE: If not samrtea wuJj yoor boda. naufti ibcfn ftithia 10 days wilhinit t^hligaSiirtit EXCEPTIONAL QUALm': All bootave quality publiijieii' (dHkmi €$pecMy sdectcd by our EdituriaJ Ekxard. (l^ubMfwr Piten Slwwn} The Etdclronlcs Englneen and Ddilgn&rs Book Club and \h& Election [CI and Control EngJnddfi' Boole Club hove joined forces to bring you a/Htie bett fJtlei from thm most piomlnenl electronics publlttiert. ELECTRONIC 1 ■ POWER li All books are tiardcovsr unless number ts loliowed by a "P" lor paperback. ly\'^\ EEQC. aiua Rklgo Suinn>Lt, PA 17294.0300 Electbowics Eng ineers' ^^^^^^^^^^H^^^^^B 800K CLUB M Blue Ritlge Summit PA 17294-0060 HYESl Pkasc accept my membership in the ELECTRONICS ENGINEER S BOOK CLUB atMl %cnd the 3 volumes listed belovp . bUlmg me S9.95^ If not satisfied. I imy mum the books u iihin toi diyi ttitisout obligatioo aiid have tny ittctnbcrship excelled, I agree to pun^ha^e at tc^i 3 books at regular Club Ihices during the next 2 ye^, and may resign any time tbcrcaitcr. A shipfring/handJing charge and s^lcs wUI be added to aJ] orders. AddnfSS City S tate . Pbone Valid for pe^- mttvlocn mtiy. Vat^i^n 4{^ivjmu ^lU rocn^c vpcxiit urxlmif^ tnumcttnm. Cinaiia miur nmut in U,S. cunerKjf Thii order i«hi«t ui Kcrpuncc h> ihc ErcciFunici* HApinn-ri' Biwk Club RPtF392 EQUIPMENT REPORTS Dallas Semiconductor Touch Memory Starter Kit The electronic equivalent of the Post- it note CD in IT 24 CIRCLE 10 on Fnee information caro P eople were once naive enough to believe thai com- puters and other office-au* tonnation equipment would bring about the "paperless office/' We haven't heard anyone suggest such a thing for some time, but Dallas Semiconductor (4401 South Belt- wood Parkway. Dallas, TX 75244) might have come up with a way to replace a good deal of paper with silicon chips. Their DS199x Touch Memory devices are non-volattle memory packaged in a button- shaped can. They can be read or written with a momentary contact. We recently had the opportunity to examine the devices and see how they work, using Dallas Semicon- ductors DS9092K Touch Memory Starter Kit. Touch Memory is available in two mam configurations: One is ROM only, the other is a combination of ROM and battery-backed RAM. The ROM-only device would be used primarily for electronic identic ficaion. If attached to an employee ID badge, for example, it could be used to permit access to secure areas of a building. The ROM/RAM device could be used for a good deal more. In manufiacturing, for in- stance a Touch Memory could be attached to the device being man- ufactured. It could contain proper calibration settings for the assem- bly technician to read. The techni- cian could then in put the results of the calibration tests into the Touch Memory, along with his identifica- tion and a date stamp. The potential applications aren't limited to electronics and manufac- turing. Imagine if your checked air- line baggage was identified by a small Touch Memory tag that not only contained your destination, but your name, address, flight itinerary, and the name of each baggage han- dler who handled your luggage — including the one who put your bags on the flight to Bogata instead of Boston. The Touch Memory Starter Kit is a good way to gel a feel for what Touch products can do. ft includes five assorted Touch Memories, a Touch Memory probe (for reading and writing the devices) an adapter that lets you attach the probe to the serial port of a PC, and a flopp/ disk that contains the interface software- Three of the five included Touch Memory devices are DS1990 "Touch Serial Numbers/' They con- tain a 64-bit ROM into which is writ- ten an 8-bit family code, a 48-bit serial number, and an 8-bit CRC (cyclical redundancy check). One of the devices is mounted to a key fob, while the other two are mounted on a "peel and stick" sheet. Two DS1991 touch memones are also provided. They contain 3 384-bit blocks of non-volatile RAM and a 64-bit ROM. The probe included with the eval- uation kit is IS stnctly for evalua- tion—its not packaged with any handle or base, and instead, hangs on the end of a pair of wires. The other end of the wire is terminated in a RJ-11 modular telephone jack. That, in turn, plugs into an adapter that converts the RJ-1 1 jack to a 25- pin D-lype connector for a PC serial port, as well as converting the com- puters RS-232 interface into a sin- gle, bi-directional data line. The probe doesn't have to look good to get across its strong points, however Most important, it's very forgiving of how it's positioned on the memory. One of the reasons the memory is packaged in a round "Mi- croCan" is becuase the curved edges can guide the pnobe for self- alignment. The one-wine data trans- fer IS what helps to make Touch Memory mgged. The top of the can is the data connection, while the edge and bottom is ground. Data is transferred at speeds up to 16.6 kilobits per second, which seems instantaneous for small memories. Even with fast data rates, it s like* ly that a momentary contact will be interrupted before a data tramsferis complete. However, the Touch Memory uses two verification tech- niques to ensure data integrity. First, data is written to a scratchpad memory and verified before it is transferred to memory. If the con- nection is broken early, the scratchpad contents won't be transferred to the main memory, so the integrity of the previous memory rs maintained. A CRC check is also performed on data. The non-volatile memory will last for five or ten years — the life of the burlt-in lithium battery. The stainless-steel case is resistant to corrosion from moisture, acid* and plain old dirt. From what we ve seen of this self- stick data carrier, we think that we may be seeing fewer bar codes, and a bit less paper If you'd like to get an idea of how they work, the Touch Memory Starter Kit is avails able for $75, R-E ONCE YOU'VE GOT IT DESIGNED, YOU'VE Now you can take those hot^ new logic or block design diagrams, and quickly, easily bring them up to reality... in mi notes., .without solder! Build circuits as fast as you can ihmk. Test. Modify. Expand. Without burned-out parts or burnt fingers. Save time* money.,, and prove thai you know thai youYe talking about.,, before you use your CAD, Specify PROTO BOARD Brand. Todays rec- ognized Standard for Quality in breadboafd- ing, Here are five expandable breadboards, offering counlless arrays of soldertess sock- ets and bus strips that emulate pc board lay- outs. Pop in components. Pop them out again. Microprocessors. Memory. Large DlPs. Ttny discretes. Makes no difference. The pat- ented aluminum backplane lets you work at Call toll-free for details 1-800-572-1028 frequencies from DC to half-a-GtgaHerlz or 500MHz, Need power? A powered PROTO BOARD Brand offers up to triple voltage power supplieSp ^ 5V, + 12V. - 12V. with reg- ulated/current limited DC power Over 2,250 tie points with 24 fC capacity and 14 pin DIPS- Super for TTL. CMOS, Op-Amps and microprocessor circuits. And lots more. Best of a]f, your hassle- free American-made PROTO BOARD Brand comes with an unlim- ited lifetime guarantee on all the breadboard sockets. Prices are so modest, you it wonder why you waited this long lo specify PROTO BOARD Brand. Order today. GLOBAL SPECIALTIES ClRCtf 186 ON FREE INFORMATION CARD Global Specialties An Irvieiplex Electronics Cixmpany. 7Q Fulton Terrace New Haven. CT 06512 Telephone: (203} 624-3 f 03 t Inierplex Electronics 19B9. AN Global Speciailies breadboards ng products made m USA. ADOIC) I r\3 9- m I o 25 NEW PRODUCTS Use the Free Information Card for more details on these products. i m 6 m 2S HANDHELD DIGITIZING SCDPE, According to Tektronix, its Model 224 60-MHz handheld digital oscilloscope is the fastest in the industry. It allows electronic service techni- cians to Iroubleshoot high- speed TTL circuits with a battery-operated unit, avi- onics technicians to get the power of a digitizing scope in the cockpit, and military-maintenance per- sonnel to perform accurate equipment servicing in re- mote land or under-sea op- erations. The 224 s TV triggering capabilities allow video repairmen to monitor and troubleshoot a wide range of imaging systems. The unit weighs just 4.4 pounds, and two re* chargeable batteries pro- vide three hours of reliable operation. The 224 dual-channel design allows input-to-out- put comparisons and its unique "Isolated Channel" architecture, in which each channel is isolated frctm the other channel and fnDm ear- th ground, makes truly safe floating measurements Cas opposed to other hand- helds that claim safe float- ing measurements simply on the basis of their plastic CIRCLE 16 ON FREE rNFORMATION CARD cases). True floating mea- surements can be made up to 400 volts per channel or 800 volts peak-tO'peak, without risk to the operator or to the device under test. Like the other members of Tektronix s popular 222 family of portable digitizing oscilloscopes, the 224 fea- tures a clear, bright CRT display; ease of use: and PC compatibility AutoSet and Autolevel Trigger aflow effortless acquisition and display of signals. Up to four front-panel setups can be defined and stored in memory, then recalled at the touch of a button. Four waveforms can be stored as reference templates or for future analysis. The 224 is 100% programmable from the RS232C port. When linked by modem, the 224 can be controlled remotely from a PC equipped with Tek's Virtual Instrument Software (CAT200X The scopes controls can be manipu- lated at the keyboard or mouse, just as th^ would be handled manually on the instrument. The 224 handheld digitiz- ing scope costs $2750. — Tektronix, Inc.. Test & Mea surement Group, RO. Box 1520, Rttsfield. MA 01202; Phone: 1-800-426-2200. DATA*ACQUISITION AND CONTROL SYSTEM FOR PC*S. Cfaimed to be the lowest-pnced general-pur- pose data-acquisition and control system for person- al computers. Praine Dig- ttal s Model 30 is available for XT Sp ATs. 386 s and PS/2 model 30 s. The sys- tems prinled'Circuit board plugs into the PC*s expan^ sion bus and occupres a t/4 slot. The unit includes CIRCLE r 0\ FREE INFOftMATlON CARD 24 lines of programmable digital input/output; an 8- channeL 8-bit A/D convert- er: and a 12-bit CMOS counter (An 8-channel. 30- volt. O.S-amp driver Is avail* aWe for an additional $5J The system communicates with the PC via four I/O memory locations and is easily interfaced to all pop- ular languages. Sample programs in BASIC. Quik* BASIC, and Assembly Ian* guage are included on a 5 V4 -inch floppy disk. The data- acquisition and control sys- tem can be used to control relays, lights, and motors; to measure temperature, pressure, and light levels; and to input switch posi- tions, thenmostats. and liq- uid levels. The Model 30 data-ac- quisition and control sys* tem costs $79.— Prairie Olgiial, Inc. 846 Seven- teenth Street. Prairie du Sac. Wl 53578: Phone/ Fax: 608-643-8599. DIGITAL CUMP^ON METER, The ACD-II autoranging, digital clamp-on meter will directly measure AC cur- rent, voltage, and resis- tance. Measurements are shown on a large* easy-to- read. 16- inch display Over- range is indicated by the CIRCLE 18 ON FREE INFORMATION CARD letters "O.L." appearing on the display. The instru- ment features circuit pro- tection to 550 volts and a low- battery indicator It has r a maximum jaw opening of 2J4 rnches. The ACD-tt meter comes with a wrist strap, a refnovable belt clip, a 9V battery, safety test leads, a carrying case, and instructions. The ACD-1! clamp-on voit/amp/ohm meter has a list pnce of $119.95.— Amprobe Instruments. 630 Merrick Road. P.O. Box 329. Lynbruok. NY 11563: Phone: 615-593-5600: Fax: 516-593-5682. MONOLITHIC OP-AMR With a unity gain bandwidth of 140 MHz. Analog Devices" ADBU is the industry's fastest monolithic opera- tional amplifier operating from a ± 15V supply. Video specifications such as gain flatness, which ensures broadcast-quality signal transmission, and differen- tial gain and phase, which CIRCll ly ON FREE INFORAt\T»ON CARD are critical for video cam- eras, multimedia systems, and special-effects units, are optimized. The AD81 f s output is capable of driving two back-terminated 75- ohm cables, making the device well-suited as a fine driver In video routers or distribution amplifiers. The ADSn current feedback amplifier meets stringent HDTV video specifica- tions, and offers the tran- sient response charac^ (eristics needed for high- speed pulsed applications such as infrared tnnaging and digital osciHoscopes. When used as a buffer for analog-to^digital or digital- to-analog converters* the 4D0/f offers low distortion and, as a result of the cur- rent feedback design, a wide bandwidth over a large range of gains. The amplifier operates from power supplies ranging from It 4.5V to :r 18V, with a minimum output drive cur- rent of 100 mA. The video- speed op^amp is available specified over the industrial C- 40X to +85X) and military C - 55^C to + 125^C) temperature ranges. Package options include an 8-pin plastic DIP, 16' and 20'pin SOiC, 8-pin Cerdip or 20-pin LCC. Specified over the indus- trial temperature range and packaged*in an 8-pin plas- tic DIR the AD81I costs $3.35 in hundreds or 52.85 in thousands. — Analog De- vices. Literature Center. 70 Shawmut Road, Canton. MA 02021: Fax: 617-821-4273 (for applica- tions assistance, contact Jay Cormier, Analog De- vices, Inc. 804 Woburn Street. Wilmington, MA 01887: Pfione: 617-937-2507). SMT PICK-AND-PLACE SYS- TEM. Designed for pro- totyping or low-volume production of surface- mount boards. O.K. Indus- tries^ SMT'880 Series Manual Pick and Place System provides up to three times greater throughput with substan- tially improved accuracy over hand placement. The operator chooses a com- ponent from the loose* component carousel or the stick or tape feeders, picks Train at HOME to be an Electronics TschniciBn \ As the demand for compuiers and mtcroproce^sof^ in by^ines^, m an ufdci Luring i^nd commurticatit^m TOntinues to grow, doe^ the neeiJ for qudiifted tectinicians. tt*^ nut unu«iual tor uxpcricnccd technicians to e^rn from $30,000 lo moft* than S40,000 a ycjr, ' Now through Peoples Colh^* ai lndeper>dent Sludies you can rrAtn tor thi^ e^tCiting ticki without interrupting your ;(}h or borne life. • Industrial lleCJJonk* & MicroprocesMW Techfiology • Communication* Eleclfonics with Micf^ proce^Kjr Technolog>' • Computer Sea icing & Electfonio T«chnotoKy • Specialiied As^iate Degw In ElecTrcMiic^ Technology Depending on the program yoo ^lect, you1l peftea your ^kilf* uving thiv ^vjTKed equipment, ir>cluded m the prtce of tuition: • IBM-Compatible Per^fiiil Computer • Dfgital Multimeter • Digital Logic Probe • Elenco OsciHo^cope • Portable Cellular Telephone i! ft^hance Your Ira Peofife* CoJIf muotiuct^ Kjnji' Tfjimng frf^t^ to make your leamtng txperienre more complefei • Accelef.it«?tl Learning Sv^tem — a Mrientificallv pfoven *ludv sv^tem that helps vou learn fa^tet arvd eA^wr than ever before. • Video Tutor Training Tafie^ ^ give ^txi a permanent, visud fecord of in^otmative lecturer And clo^e-up demafr'! For COLOR CATALOG Mail Coupon or^ ll^Cali TOLL FREE 1 -8 Q 0-765-724 7 jH ftngTjjii^ nfjeiwJ (ifv*! HI LndrU >i^U*\ C^fuiitf. f'«t-jTiJ if ifo Ckir programs a#e accicdtted by the Accrediting; Commrssion oi the >^aiiOfial Home SiimH' CourKil YES! I woytd like lo kncm more about your training prograrm. Sertd a catalog loc ^£am€ Address Gty Stale Zip Phone ff Peoples College 233 Academy Drive • P.O. Bos 421766 Krssimmce, FL 34742- 1 76fl MrfT*«r, D I . FtvpWt Ct ruu p R 0392 I P :d O 8 27 CIRCLE 133 ON FREE INFORMATION CARD CIRCLE 20 ON fREE INFORMATION CARD it up with the vacuum head, and then guides it with the free-floating X-Y-Z arm to the appropriate position on the board. A control knob on the vacuum head pro- vides theta rotation to en- sure proper component orientation. When the com- ponent is lowered, the vac- uum head automatically releases it when contact with the board is made. The SMT800 provides a total vwjrking area of 8 x 12 inches p with an adjustable board holder. The system comes complete with an ESD-safe carousel vacuum pump and a movable hand rest that glides over the board holder and provides the user with a stable, fa- tigue-relieving platform. For easy compatibility with larger automatic machines, optional tape and stick feeders mount on the vise. Other options include a lighted magnifier with four diopter lenses to assist in component alignment. The system is available for US- volt or 230- volt operation. Prices for the SMT-800 pick-and-piace system start at $3495,— O.K. In- dustries. 4 Executive Piaza. Yonkers. NY 10701: Phone: 914-969-6800. PLCC QUAD CLIP Kit The selection of test adapters included in ITT Pomona's Model 55t5A PLCC Quad Clip Kit was specifically chosen to test the most popular surface-mounted plastic leaded chip carriers CPCC and PLCC) with "J^* leads CJEDECMO^047 and MO 052X The design of each test adapter incorpo- rates a "snap ring" that al- lows the quad clip to fit directly onto an IC and pro- vides simuilaneoos access to alt the pins of the sur- face mount device for hands-free testing. The wipe action of the snap- ring design, as it is pushed down with normal force into position against the contact, wedges against the IC for a tight fit and as- sures a good connection. CIRCLE 21 ON FREE INFOftMATION CARD The kit contains seven items: one each 20-. 28-. 32- (7x9. EEPROMX 44-. 52. 68', and 84-pin Pomona Quad Clip test adapters. All the adapters have gold*plated center contacts, silver-plated bodies, and 0.064mm C0.025'inch) square pins staggered on 2,54mm CO.lOO-inch) centers. The kit is packaged in a durable, reusable plastic case. The 55t5A PLCC Quad Clip Kit costs $245.— ITT Pomona Electronics. 1500 East Ninth Street. RO. Box 2767. Pomona. CA91769; Phone: 714'469'2900: Fax: 714-629-3317, CONTROLLERS/INDICA- TORS. For start, stop, or limit control of a wide range of process variables, Sim- pson Electronics has inlfD- duced the Hawk Series of controllers/indicators that fit in a Ve DIN cutout. The series offers high accuracy and ease of installation in electrical, chemical, pe- trochemical, and other pro- cess industries. The con- trollers accept AC and DC voltage and current. 4-20- mA DC. 1-5V DC resis^ tance, 3-wirB potentiome- ter. Frequency, and ta- chometer CRPM) inputs RTD inputs may be two-. three% or four-wire config- uration. The Hawk models also accept several ther- mocouple types, including J, K, R. and S. which input without calibration or inter- nal hardware changes. The compact units are AC or DC powered and are housed in impact-resistant, fiame-retardant. plastic cases. Their front- pan el keypads are used to pro- gram, set, or check the op- erating parameters of hys- teresis, time delay, and set point, as well as alarm lev- els and relay settings. A user password prevents unauthorized program ac- cess. Each instrument also features a highly visible, 0.51 -inch, red LED display: plug-in circuit boards for user-selected functions; dual set point with optional 3D4 CIRCLE 22 ON FREE INFOI?MATlON CARD dual relays: a fast, easy, in- put terminal block that can be unpfugged: and an edge-type connector for analog and digital output options. The Hawk Series of con- trollers/indtcators are priced starting at $199, — Simpson Electric Company. 833 Dundee Avenue. Elgin. IL 60120-3090; Phone: 708-697-2260; Fax: 708-697-2272. PC AUDIO CONTROL SOFT- WARE, Voyelra's Sound Central, a software utility for Windows 3.0. pnDvides a convenient way to control CIRCLE 23 ON FREE INFORMATION CARD every aspect of sound gen- erated by PC sound cards or Multimedia PCs CMPCX Its graphical audio editor can be used to audition and edit digital waveforms in the VOC or .WAV format and modify them with such special effects as echo, data compression, bit reso- lution, and sample-rate conversion. A MIDI song- file editor provides control over major parameters in a MIDI song file so that tf>e music generated by the file can be manipulated — for instance, re-orchestrated, lengthened, or shortened. The fulhfeatured CD '"con- trol panel" provides a con- venient way to sort, view, and play CD audio tracks. A mixer control panel pro- vides access to all of the MPCs mixer functions in- cluding input/output con- trol levels and line/mic monitor settings. Also in- cluded are a MIDI file map- per and a "patch editor" for the MPC s FM synthesizer Sound Central audio control software has a sug- gested retail price of $199.95 —Voyetra Tech- nologies. 333 Fifth Avenue. Ptelham, NY 10803; Phone: 1-800-233-9377 or 914-738-4500: Fax: 914-7386946, OSCILLOSCOPE PROBE SWITCH, Providing a simple way to observe and com* pare waveforms at different points in a circuitn Microvolt DONT GAMBLE when you want the best 2 1 Reasons To Buy OPTOELECTRONICS' MODEL 3000 u RANGE- lOHz to 3GH2. z HhSpeed ASIC {Application Specific Integrated Circuit) State-Of-The-Art, 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 Baf graph - 16 Segment, Zero & Full Scale Adjust. Excellent for locating Hidden Transmitters, Four extremely Fast Gate Times -01, .1.1, 10 sec. Dual High Impedance Ampfifters. Maximized Sensitivity Hold Switch ' Locks in measurements FAST. II* ± IPPIv^ Accuracy 1 2. Direct Count - IHz resolution to 220MH2 13. Sensitivity <1mv10MH2'20C»^Hz,<5mv- 2GHz. 14, Single Shot Time lnten;al 100ns. .1ns averaged. 15, Push-button Input Gate & Function selectioo. 16. Extnided Aluminum Enclosure. 17, NtCad & Charger tnduded. IS, Low Battery Indicalof. 19, 1 Year Parts & Labor Warranty 20, 30 day Money Back Guarantee. 21, OPTOELECTRONICS backs this witti our 18 Years of Dependability & Service. Ail this and more for the Low Price • $375. Also Available at Special Package Price: For A Limited Time Onty Model 3000. Backlight/Beeper. Carry Case & TA- 1 00s Whip Antenna All this for only $449. OPTIOIIS! TCXO 30 ± ,2ppmTCX0„. $100, BLa30 7^ Back .^gM & r#o sigrial level indicator 75, \ CC30 Carry Case , S 15. TA100S Totescoping Whip Aritenna $ 12. Factory Direct Order Line 1-800-327-5912 (305)771-2050 • FAX(305) • 2052 5821 NE 14th Ave, * Ft, Uuderdale, FL 33334 5% Ship/Shanciling (Max. $10) U.S. a Canada. 15% outside ooniir>enta! U.S. Visa a Masier Card Accepled. CIRCLE ISO OH FREE INFOHMATton CARD YOU CANT LOSE! C1RC1E 24 ON FREE (NFORI^UTION CARD Engineering's MVtOS os- alloscope probe switch ac- cepts two scope probes and attaches to the os- cilloscope input. The ac- cessory allows the user to easily select either of the two probes with the flip of a switch. With the MW03, a dual-channel scope can ac- cept four separate inputs without performance deg- radation. High-frequency relay technology provides high isolation and low inser- tion loss. Compact all-met- al design provides excel- lent shielding and allows the MVW3 to be installed directly on the input BNC connector of the os- cilloscope. The switch can also be used as a stand- alone, general-purpose RF switch The MV?03 oscil- loscope probe switch costs S275.00— Microvolt Engineering. PO Sox 777. Tustin. CA 92680: Phone: 714-544-3441. EMI/RFI FILTERS. When controlling electromag- netic and radio frequency interference to the environ- ment and complying with FCC regulations on max- imum level emissions are concerns, the 60/ Sehes of surface-mount resistor- capacitor networks from Bourns provide a simple CIRCU IS ON FREE INFORMATION CARD solution. Shielding rs re- quired between the RS232 connector and the input/ output drivers in electronic equipment. The 601 Series of fow-pass Filters prevent the transmission of high- frequency noise compo* nents and are especially effective on lines to exter- nal connectors- Featuring a T*con figuration of 16 re- sistors in sehes and 8 ca- pacitors bused to a com- mon ground, the surface- mounted RC networks can suppress high-frequency EMI/RFI noise for up to eight separate lines. Small* er than inductive-type fil- ters, the devices are packaged m wide-body SO cases. Typical applications for the filters are in person- al computers, data termi- nals, test equipment, and process controllers for high-frequency suppres- sion into or out of elec- tronic equipment. Prices for the 601 Series of surface-mount EMI/RFI filters begin at $2.15 each in quantities of 10.000 pieces —Bourns Networks, Inc., 1400 North 1000 West, Logan. UT 84321; Phone: 801-750-7200. R-E NEW LIT Use The Free information Card for fast response. HOW TO GET ANYTHING ON ANYBODY: BOOK II; by Lee Lapin, ISECO. Inc . 2228 South El Camino Real //349; San Mateo, CA 94403; Phone: 415-513-5549; Fax: 415-578-8741; S38.00 postpaid (plus 8% sales tax on California orders). If the words "es- pionage*' and "spying*^ bring to mind James Bond Cor Maxwell Smart), you're bving a couple of decades in the past. These days, just about everyone can snoop tor be snooped upon), thanks to the huge assortment of personal surveillance devices now available. Subtitled "The Encyclopedia of Personal Surveillance/' this book provides a guided tour of audio surveillance, includ- ing unconventional bugs. HOWTOCTTAISIYllJK^^ ON ANYBODY CIRCLE 40 ON FREE INFORAUTION CARD parallel and serial taps, car- rier-current bugs, and IR and encrypted transmit- ters: acoustic analysis and hardwiring, including how to purchase and how to plant super-sensitive sub- miniature microphones; video surveillance using special cameras and trick lenses hidden in everyday Items, inexpensive wire- less systems, and using TV's as surveillance de- vices: and cellular tele- phone operations and inter- cepts. The book also explains how to tail some- one, how to obtain con- fidential phone-connpany records, how to see and hear thnDugh walls, how to use infrared devices for night vision, and how to tap into a phone with no equip- ment. It describes the art of surveillance photography and shows how to put to- gether a complete dossier on anybody. Also included are legal guidelines and the addresses of more than 200 suppliers of sur- veillance and counter-sur- veillance gear. COMPUTER VJRUSES AND DATA PROTECTION; by Rail Burger. Abacus, 5370 52rici Street SE, Grand Rapids, Ml 74512; Phone: 618-698-0330; Fax: 616-698-0325; S19.95. Computer viruses — pro- grams with the potential to destroy data and disable computer systems — can be quite costly m temns of lost time. data, and money. The best protection against such viruses is educa- tion — learning what steps to take to minimize or avoid losses- Intended as a gen- eral guide rather than a ref- erence work, this book ainns to teach readers about ail kinds of computer viruses to allow them to protect themselves. Begin- ning with a short history of viruses and a description of CIRCLE 39 ON FREE INFORMATION CARD how a virus can gain contnDl over a computer, the book explains how viruses are created and how to remove them From a system. It ex- plores the design and func- tion of viral programs, and includes sample program listings in BASIC, Pascal, and machine language as well as examples of viral software manipulation. The book outlines the protec- tion options available, and provides practical advice about what to do when your PC is infected. Along with examples of protec- tion viruses and strategies, a simple virus-detection pjDgram in provided. In ad- dition, the book explains how to design virus proof operating systems, HOMEREMOTE'CONTROLS AUTOMATION PBOJECTS (SECOND EDITION); by De- Iton T Horn. TAB Books, Di- vision of McGraw-Hill Inc., Blue Ridge Summit, PA 17294-0850; Phone: 1-800-822-8138; $18 J5. Besides being practical and educational, the proj- ects described In this book are sure to impress your friends and family. Remote- control and automation projects can also save you both time and money, by letting electronics do the job for you. Although the emphasis is on the prac- tical—in the form of 77 dif- ferent projects — the book does provide background information on the basics of remote control, mechan- ical devices H motors, sen- sors, digitally-controlled potentiometer IC's. and building and safety pro- cedures. The projects themselves fall into 1 1 cate- gories: lighting, doors and windows, temperature contnoL liquid contrctl. au- dio and video, telephone, motor control, electronic switching, timers, wireless control, and computer con- circle 38 on free infoRpMation card troL The second edition presents 15 a It- new proj- ects and updates and im- provements of the original projects. Each project is accompanied by a circuit drawing and a parts list, and most are fairly simple to build. Most of them can also be adapted in various ways to meet other, custom applications, TRDUBLESHDOTING AND REPAIRING FAX MACHINES; by Gordon McComb. TAB Books, Division of McGraw- Hill Inc., Blue Ridge Sum- mit, PA 17294-0850; Tel, 1-800-822-8138; S16.95. It stands to reason that as soon as an electronic device becomes a necessi- ty in our homes or offices, the need arises for people who know how to maintain and repair that device. This book was written to pro- vide that know-how to the non-technical fax owner. By following its instructions, and using a few inexpen- sive tools, consumers should be able to keep their fax machines in prop- er working order- — and to recognize a major problem that must be handled by a professional repair person. Aimed at non-technical folks, the book provides plenty of background infor- mation about how fax ma- chines work. Most of the book is devoted to the trou- bleshooting and repair of mechanical problems, which account for about 85% of fax breakdowns. Full coverage of the major electronic subsystems- power supplies, solenoid controls, etc, — is also pro- vided. Because most prob- lems that occur with fax machines involve such things as dirty switch con- tacts or printing elements, broken wires, aging rubber belts and rollers, and damaged paper preven- tative maintenance is em- phasized. Simple illus- trated instructions show how to clean and lubricate the paper path, light-sen- sitive reader bar, thermal printing mechanism, paper CIRCLE :J7 ON F REE INFORMATION CARD cutter, fluorescent lamp, and front-panel controls. The book also explains how to diagnose and fix bad phone connections and printing and transmis- sion errors. Emergency first-aid procedures in case of fire or water damage are detailed. An entire chapter is devoted to troubleshoot- ing flowcharts illustrating the proper steps to follow to locate and solve prob- lems. MS-DOS 5 QUICK REFER^ ENCE; by Timothy S. Stanley. Que, 11711 Nortti College Avenue, Suite 140, Carmel, IN 46032; Tel: 1-317-573-2500; $9.95. This slim volume puts the essentials of MSOOS 5 at your fingertips, provid- ing an instant reference to critical commands and pro- cedures, batch files, the MS-DOS 5 QViCK CIRCLE 36 ON FREE INFORMATION CARD DOS Editor, and error mes- sages. Short on documen- tation, but full of practical pointers, the book is in- tended as a supplement to a full size MS-DOS guide. It explains the proper use of primary DOS functions, as well as advice on how to avoid making serious er- rors. In a compact, easy-to- use format, the book ex- plains the proper DOS commands to use for spe- cific operations. The book is arranged alphabetically by command. Each com- mand name is accom- panied by an explanation of its purpose, followed by the syntax needed to in- voke the command and the rules for its use. Examples are provided for some of the commands. Separate sections provide in-depth coverage of batch fifes, the DOS Editor, MS-DOS messages, and error mes- sages. A "DOS Survival Guide" lists specific pro- cedures and the com- mands needed to invoke them. R-E Now! Experience the electronics behind the MIDI revolution as you build your own computer-controlled music center Only NRJ's innovative^ at4iome tmining in Oectronic Music Teduiology gives yon handson experience willi tlie equipment Uiat's revolutionizing tiie music industry — Atari ST Series computer with buijt4n MIDI ports, Casio HT-3000 syntiiesizer wilii advanced MID] operations, and ingenious MIDI software that Units computer itcyboard to syntiiesizer keyboard— all youtB to train with and keepi This year, over S 1 .5 billion worth of digital electronic music instruments, Jrom keyboards to drum machines, will be sold in the U.S. alone. Bitiiusi- asts everywhere — professional musiciajis and recording technicians, even people who have never touched a musical instrument before^^e discovering the excitement of today s electrojilc music technology. At the heart of this excitement is MIDI (Ntusical Instrument Digital Interface), an innovation that's transfonned musical instruments into the ultimate computer peripherals... aiid oi>enetl up a whole new world of opportunity' for the person who knows how to use> program, and service this extraordinary new digital equipment. Now NRI's breaklh rough TJeclronic Mu.sic Technology' course puts you at the forefront of this booming new technology with exclusive training built around a MIDI- equipi>ed computer, MIDI synthesizer, and MIDI softwwe you keep. Dl^amic new technology opens op new career opportunities Tlie opportunities are unlimited for the pjerson who's trainetl to take advantage of today s electronic music phenomenon. Now you can prepare for a higti-paying career as a sound engineer, recording engineer, or road technician . , , even start your own business selling and senicing today's high4ech musical instruments. Or simply unleash your own musical creativity with the breakthrough traiiiing and equipment only NRI gives you. i^ OnTy NRI gives you hands^in training witli todays MIDI technology The Atari ST Series computer included in your course becomes the heart of your own 1 5 sia E computer- control lecl ma^ic center. With its tremendous power, superior graphics capabilities, and built-in MIDI interface, the l6/32'blt Atari ST has almost overnight t>ecome the computer of choice for todays most knowledgeable electronic musicians. Your Casio HT-IKKK) synthesizer features a five-octave, MlDk:omt)atibIe digital keyboard will) built-in monitor sj^akers. advanced tone editing and wrilirsg, i>attern memory, keyboard sjilit, tone and rhythm banks, chord niemory, and dozens more state<)f-t he-art caiiahilities. Plus you get ingeniously designed MIDI software that opens ui> ama/Jng new creative and technical possibilities. you actually build your outi 4input audio mixer/amplifier. . .and you test the elec- tronic circuits at the core of today^s new equipment with the hand-hekl digital multimeter also included in your course* No previous electronics or music experieiice necessary No matter what your background, NRI gives you tiie skills you need to take advantage of l' step by step, gaijiing the full umlerstafiding of electronics that^s now so essentia] for technicians and musicians alike. You move on to analyze sound generation tech- niques, digital logic, micrijpnxressor funda- mentals, and s<'uni>ling and rc*cording tech- niques.., ultimately getting first-hand experience with today's exi)losive new technology as you explore MIDI, waves haj^ing, patching, sequencing, mixing, s|jecial effects, and much more. Plus, even if you Ve never been involved with music before, NRI gives you enough basic training in music theory and musical notation to appreciate the creative potential and fcir-reaching applications of today s electronic tnusic eciuipment. Send today for FREE catalog II the cou]X)n is missing, write to NRI Schools, McGraw*Hill Continuing E^lucation Center, ^MOI Connecticut Avenue, NW, Washington, DC 20008, Schools McGraw-ttilE ConlliHiing F.{tutMti{j]i Cciite 4101 Connecltcm Avenue. Washlugion. IK 20008 Check One FREE Catalog Only U Etectroatc M uai c T(!!Chnotag3i' H: Miejr{H:c}riiput^r Sen'i^iri|j Cornputtr rn^graniining □ TV/VMeo/AudioSt^rvking !_; Desktop J^ylihshtng and l>eslgn G Security Electronics □ Rctlon/NotifLctkin Writing □ Easic EJectronics P Bookkeeping & Account img Name -Age. SRf rniiniii^ indades an Ainri ST comptiieK Casio iyndfesi^er. exctmtve MlDiso^^n', ttmfitiuch niof^— aliyxHiTs to miin ii ith and keep! Address _ City/Stiite/yjp 3032 J BUILD THIS MIDI INTERFACE URK Bring this ver JOHN SIMONV our PC with ' interface,. i^JltTATlON AFTER A LON(i TKKM V the marriage of conipiitt musical instnimenls has consummated, thanks to MIDL the Musical Instrument Digital Interface, The fruits of this union are sequencer pro^^rams with the look and feci of a multl track recording studio, Ushig those and other PC-based tools, a single musician tn a back bed room can produce recordings that only a few years ago re quired orchestras and an oflice staff. Professional musicians arcn^t the only ones lo beneiil — you can too. Instruments with MIDI Interfaces are so common that even your local discount store probably has several to choose from. The only thing standing between you and Che artistic gratification of writing and per- forming like the philharmonic is the interface from your PC to the MIDI world* so lels take care of that little detail right now. Well show you how to build a MIDI interface that is both low^ ct>st for the beginner and up- gradable for the serious user. With little further delay we be- gin, but first.,. I A Uttlc histor^^ ^ ^ The MIDI specificaUonV whicfi Vi^B written with low-cosf hard- Wiff^ in mind, allows us to use HD6850P Universal v^iroi^ous Receiver Trans* TI chip. The 6850 is the hills, readily jteSpCfisive, and ^ the 3L35 kilo- fetiuiired tor iapMIDI in- ITDr^e Asyn miller (0? older Utarf available, i easily produc baud signal ihd MIDL The basis iprface is that UAK one oi the PC s outp more lnformatiQii.Qr Radio-Electrontcs. 1989. The most frequent MI maiidsare NOTE^^Mand noteoi as keys are pressed and re leased. Those messages happen relatively Infrequently; even when a chord is played, there is generally a slight delay between the individual notes. But the protocol also has provisions for eonlinuous controllers such as pilch wheels and foot pedals, and the messages that signal that kind of activity can really spew out data. With nothing more than a tJART for an inter- face, the original IBM PC. with its 4.77-MHz 8088 MPU and 8 scr. but vironmenl \v mcnt, there Is th lliat data can be k liule pilch wheel inforTff oo slow Siiiximum Somuch of Vocational fsslonal en- s oi' c^quijEi-.'' possibllitv Loslni? a \su\ usually I he eyiijjftlie world, but if a No i K^So^te^ OFF command coi^M in^^ middle of it, missin iffli at diV^M a ver\' big deal. flHj The lirsl widely a^^Stoi^mCT interface to overcome tha^^uj lem was the MPU-401 made by Roland, II has Its own dedicated processor and memory, and gels around the lost-data problem by maintaining a first-ln-firsl-oul (FIFO) buffer for the MIDI data Radio*Eleclronics. March i9§2 COMPONENT SIDE <- A100K 4 IF Q A C jiLiii K E 01 1N4I4S R7 220Q MIDI IN 1 MIDJ INU MIDI OUT 1+ MIDI OUT 1- MIOI GUD t MIDI IN2» MIDI IN 2-1^ MIDI OUT 2+ MIDI OUT 2- MIDI GNO 2 CI BRACKET SOLDER SIDE P1J_ Bl IR02B4 85 B7 BIO Bll ai2 mm mm BIS BIB B17 BIB B19 §20 822 B23 1RQ4B24 ■R03B25 B26 B27 fi2B B29 SSI C5 -01 received. It also does some tricks such as data filtering and providing a metronome. All well and good, but the in- troduction ol' the first XT-class PARTS LIST All resistors are Va-watt, 5%, un- less otherwise noted. R1, R2, R5. Rt1, R13*— 3300 ohms R3, R4— 10.000 ohms R&— 12,000 ohms R7. m\ R9. R12\ R16. R17*— 220 ohms RIO, R14*— 100.0Q0 ohms R15— 3300 ohms x 7, S-prn SIP Capacitors C1-C5— 0.01 Mylar C6— 0,1 \if. Mylar Semiconductors 1C1— 74HC00 quad NAND gate IC2— 74HC393 dual 4-bit binary counter IC3--74HC245 octal transceiver IC4, ICIO'— TIL111 opto-coupler ICS— 74HC138 3-to-8 line decoder IC6--74HC04 hex inverter IC7, IC8*— 6850 UART IC9— 74HC688 8-brt magnitude comparator D1, 1N4148 silicon diode Other components J1, J2, J3*, J4'-"inline 5-pin female DIN connector JU1— 8-pin IDC header w/jumper blocks 81— 7-posltion DIP switch XTAL1— 2 MHz crystal Note: Components marked with 3 are optional for a second MIDI in/out. Miscellaneous: Printed circuit boardt hold-down bracket, wire, solder, etc. Mote: The following are available from PAIA Electronics, Inc., 320Q Teakwood Ln., Edmonds OK 73013 (405) 34D-6300; • PCM68pc double-sided, plated thro, PC board and bracket— $24,95 • PCM68k kit of all parts needed to build the single-port Interface, including PC board, bracket, wire, MIDI jacks, etc.^ — $49.95 • PCM68ex expander parts for adding second MIDI port — $14.95 • MIDIpac MIDI starter set con- sisting of PCM6dk interface kit and Voyetra SPJr, 64-track polyphonic sequencer soft* ware for PC/clones — $99.00 Add $3.00 P&H per order. PC made an intelligent interface unnecessary because the com- puter alone was fast enough to handle the throughput. As fast- er and more powerful PCs have become available, the need for an intelligent interface has de- creased until finally the MPU-401 has technically be- come a bottle-neck in the sys- tem (though you would never notice that the interface is slow- ing things down). What has turned out to be a noticeable problem to serious users is the bandwidth limita- tion of the MIDI channel itself. The solution to that problem has iDccn multiple, separate In and Out Jacks, equivalent to multiple interface cards. And here the MPU-401 runs into se- rious problems. Synchronizing multiple 401s is not trivial— and worse than that> each has to have its own slot and dedi- cated interrupt. Interrupts and slots, is there anything more precious in the PC world? You can switch MPU-40rs into a "dumb" mode so that several of them share an Interrupt. But then you have expensive UARTs and serious slot depletion. So. htwing faster computers and the need for lower-cost multi-port interfaces has start- ed a resurgence of interest in UART's. and all software pub- lishers support them. De-facto standards being what they are. the MPU-401 "standard" con- tinues to hang on, Bui mean- while, really hip "power users" are stepping back in time to just the sort of card that well come up with here. Design analysis The 6850 UARTs, which are (he heart of our MIDI interface, are shown as IC7 and. op- tionally ICS in the schematic Pig. 1 . The circuit can be built in either a single-port version for the beginner or dual-port ver- sion for the more demanding user Much of the rest of the cir- cuitry is concerned with decod- ing addresses and managing control lines on the PC s slot. The lowest-order address line (ao) directly drives the rs (HiiGi5'ri:K select) pins (pin 11) of the UART's to allow selection of either Status/Control or Data registers internal to the chip. Well look at what those registers do when we test the interface. The next tw^o address lines (ai and A2) are not used, so each chip occupies 8 bytes of space consisting of four 2-byte chunks which overlay one an- other. The next seven address lines (A3-A9) are routed to one set of inputs on IC9. a 74HC688 8-blt magnitude comparator. The other "side" of IC9 connects to DIP switch SI and seven pull-up resistors in SIP-network R15. When the pattern of bits from the address bus matches the pattern of bits set by SI, pin 19 is pulled low Notice that the 8th input to IC9 (gy, pin 18) is grounded on one side and con- nects to the slot's AEN on the other (P7, pin 17). An address match will be valid only when AEN (address EiNABLE) is low, in- dicating that it's not the DMA controller that has the bus. An address match does two things. It strobes 1C3, a 74HC245 transceiver, which routes data either from the slot to the card or from the card to the slot depending on the direc- tion selected by the Ion ( i/o read) line (which connects to the dir pin (pin 1) of the chip). It also enables 1C5. a 74HCI38 3-to-8 line decoder which does the final address decoding for UART selection. UART rC7 is selected when Ai 1-A13 match the pattern Oh» and IC8 is selected when the pattern is 2h. low (i/o wr[te) ties to the imv pins of the UARTs to select either a read or write to the chips. The mg (iNTERRUPT request) output pins of the two UART's are pulled up by Rl and R2 and combined by nand gate ICl-c so ^ that an interrupt request by ei- ^ ther of them shows up on a line ^ which can be routed to irq2, g IRQ3, 1R94, or 1H97 depending on ^ the placement of jumper JUL ^ Subsequently, the software will o poll the two UARTs to deter- m mine which of them generated the interrupt, § A 500- kHz transmit and re- 2 ceive clock starts out with the oscillator formed by the two NAND gates ICl-b and ICl-d, The 35 frequencv of the oscillalor Is set to 2 MHz by crystal XTALl which is then divided by 4 in one section ol the 74HC393 dual 4-bit binarv^ counter IC2. T\vo TlLl U opto-couplers (IC4 and ICIO) are usrd on the MIDI inputs to prevent grounds though the path. A continuous fjround on the MiDI inputs would likely duplicate a similar ground at the audi(* inputs and outputs, leading to tirculating ground currents and noisv au- dio. The TlLIU s are not the fastest opto's in the world, but are more than fast enough lor this application and less expen- sive than their faster brothers* On the MIDI outputs, two inver- ter stages from 1C6 are paral- leled to increase drive current capabilities. Assembly Because things run fairly slowly on slot I/O operations of even the fastest PC, I here are no extraordinarily high frequen- cies involved on the PCM68. That means that prototyping boards and wire- wrap can be used to put together a card If you like. Be careful, though: 0.8-inch spacing between slots in a PC doesn't leave a tot of room for wire-wrap pins. And a misplaced conductor can cause a lot of damage in no time at all. It should go without saying that the shortest possible wires should be used to get a signal from the card edge to the tC it connects to. Of course it*s always best to use a PC board for any project, and you can either make your own from the foil patterns we Ve provided, or purchase a ready- made board from the source mentioned in the parts list. A parts-placement diagram is shown in Fig. 2. IC sockets can be used, but certainly are not necessar)'^. Note that if you've elected to put together the sin- gle MIDI in/out configuration, you can leave oul the following parts: IC8. ICIO. D2. R8. R12--R14, and R17. Since PC-slot access holes weren't designed with MID! in mind, they typically aren*t wide enough for DIN connectors to peek through. Current practice JOfiLl R2^t'(i P ICS. ] tC2 C4 SI R1S 2 3 4 7 mo BTl*-— 4 44 [Uiiiiitiiittttiiiiiiiiiiiiiiil FIG. 2— PARTS-PLACEMENT DIAGRAM, !f you've elected to put together the single MIDI in out configuration, you can leave out ICa, LC10, 02, R8, R12-R14, and R17. FtG, 3— PC-SLOT ACCESS HOLES aren't wtde enough for DIN connectors, so we hang jn-llne female connectors out on pigtails. Labeling the connectors will make tt easier to tell them apart. FIG- 4— TH E COMPLETED PROTOTYPE CARD. The MfOI jacks are wired directly to the circuit board using sliielded twisted pair FJG,5— THE CARD FITS through the computer's rear slot. on many interfaces is simply to hang in-line female connectors oul on pig-tails and that's what well do here. The circuit board end of those connections can be soldered directly to the circuit board. Use 6-incli lengths of shielded, twisted pair; sec Fig. 3. Note that while the shield's drain wire (the wire that con- nects to the shield itself) is sol- dered to pin 2 of all the DIN connectors, it connects to the circuit board ground only on the MIDI outputs- Be sure to slide a 'A-inch rubber groin met onto each wire as shown in Fig, 3 before soldering both ends of the wires. Us a good idea to label the connectors, as they are all identical and it will be hard to tell them apart once things arc sealed up. Figure 4 shows ttie completed prototj^pe card, InstaUatioa When it comes time to install the card in your PCyoull notice right away that the DIN con* nectors won t fit through the hole in the back of the case. But by now you've probably also noticed that the interface is somewhat smaller than a usual card, and thats because the card itself is designed to fit through the rear of the PC (see Fig. 51 A hold-down bracket for the PCM68, shown in Fig. 6. can be fabricated from any material that's handy; ours is bent from 0.040-inch aluminum. After the card is slipped through the access hole In the case, the bracket mounts to the card with two small "L ' brackets, and the rubber grammets that you slid on the wires during assembly fit into the notches in the bracket. Finally push the card down into the selected slot and secure the whole affair with the traditional screw at the top. Address/interrupt selection Tht: t/O addresses that the MIDI chainiels on the PCM68 occupy arc selected by DIP- switchSL Ms fairly common for software to delauU to an ad- dress of h330 for the lirsl set of connectors, and Fig. 7 shows the setting of the switches for that situation. If it turns out that there is a conflict, the switches can be set to any ad- dress from hO-h3f8. Any soft- w^are that you select w^ill have some provisions outlined in the owners manual for changing the port address. If youVe built the Interface with two ports, the second pair of inputs and outputs wiU be at the tJase addn^ss set by SI plus lOOOh. If the first port is at 330h. the second port will be at 1330h, For interrupts, irq2 is nor- mal, and placing a jumper at that location on JUI will set the card that way (sec Fig. 8). If there s a conflict, the jumper can be set to send interrupts to IRQ4 (COM2K I Kg:* (COMl), and IRQ? (LPTl. Thats about the order you should try them in if you have to search for one that's unused- Your software will probably default to ikq2 lor pos- sibly iHQii vvh ich is re-directed to IKQ2 In ATs) and will definitely have some provisions for chang- ing the default if needed. Testing Your software will have a com- plete lest of the interface, but well do some simple tests here that will give you a feel for what's going on and confirm that things are working properly In- lU 3d lerface tests check to see that data sent from the output side appear at the input side, so the first step is to connect the input to the output with a MIDI Jumper cable. Well use DOS's handy do-ail tool. DEBUG, to directly control the UART and see that it can talk to itself — one of the few cases where that is an indica- tion of sanity. After making sure that DEBUG exists somewhere In the path of your system, in- voke it by simply typing "debug*" at the DOS prompt, DEBUG re- >debug -o330 03 -0 330 15 -o33t aa - i 331 AA TABLE 1 This resets the UART /1 6, 8 data bits, 1 stop bit Write hAA to the output data register Read the input data register Alright, a response! Now what? sponds with its own prompt. A 6850 UART has four inter- nal rejJisters; two read-only and two write-only. When the UAl^T's Ks lAol line is low. a write MIDI JWTERfiftCE 4-40 Nurs^ BRACKET NOTE THREADED HOLE UffTHREAOED HOLE ^-^^RW^METS ^ ImiONOTCHES^ 4 -40 X 1/4' MACHIHE SCREWS FIG. 6— A HOLD^DOWN BRACKET was fabricated from 0.04 0*1 nch alumiaum. After the card f$ slipped through the access hole in the case^ the bracket mounts to the card with two small "L" brackets. AIL SWiTCHES OM FOR hO on A9 AS A7 A6 A5 A4 A3 SWITCHES SET FOB h33G ON oqoooooo o \. \ "i, ^, \, ^ \. A9 AS A7 A6 AS A4 A3 ALL SWrrCHES OFT FOfi h3F8 FIG. 7— THE 10 ADDRESSES that the MIDI channels on the PCM68 occupy are selected by DIP-s witch SI, Setting the address DIP switches as shown here puts the interface on port h330. Operation puts data into the Control Register which sets the chips operating parameters and a read brings back the con- tents of a Status Register which is information on whether the transmit and receive registers e -0 O i * ^ o o o o o SOLDER 9DC SOLDER SIDE of the MIDI Interface card. 5"iM INCHES- are empty or full One address higher up (hs high) are the Data Registers, and writing to that address sends data out on the serial output, while reading brings back anything which has been received from the se- rial input. Unlike some interface chips, a 6850 has no hardware reset line. Instead, a Yeset word" is written into the Control Regis- ten The first part of our lest will be to do that bv entering "o 330 03" from the keyboard. To DE- BUG that means to write (out- put) the datum 03h to the port at address 330h. "03" is the re- set word and if you have set up the base address to be other than 330h you will want lo change that part of your entry. The next Instruction will be *'o 330 15/^ and that writes a byte to the Control Register which sets the UART to a mode of 8 data bits and one stop bit and sets the internal frequency di- vider on the transmit and re- ceive clocks to divide by 16, Now we output a byte by iyp- ing'o 331 aa" which UTites the datum hAA to the Data Register of the UART. which in turn sends the data out seriallv': To see that the data was received, the entry "i 331" reads (inputs) from port h331 and should cause the screen to display "AA, " The test process is summarized in 'mble L The pattern in T^ble 1 shows how you can write whatever datayoulikewith"o331 xx'and check to see that the data was received with * i 33 L" The sec- ond port, if you have one, can be checked by writing the reset and setup words to hl330 and writing and reading data to hl33L Using the interface After installing your software foliouMng its publisher's in- structions and fully testing the interface using their tests. MOVE JUMPER TO SET iNTiRRUPT ■ ■ ■ IRQ 2 ■ m ■ 2 3 4 7 m B m ■ IRQ 3 m m m ■ 2 3 4 7 m ■ @ m IRQ 4 m ■ 11 m 2 3 4 7 ■ m m m IRQ 7 ■ m m m 2 3 4 7 FIG,8--JU1 SETS THE INTERRUPT (see text). you*re ready to plug things to- gether and start composing and recording. As you become more involved with MIDL you'll real- ize that there are a lot of dif- ferent ways to hook things up, depending on what wu re going to be doing. But the simplest con- figuration for the beginner is simply to use MIDI patch cords to connect the MIDI output of your kej^board to the MIDI input of the PCM68 and vice versa. Tlie keyboard that you choose may have its own nutans of en- abling MIDI, such as a slide switch which lias a "MID! " posi- tion or something similar Of course that switch should beset appropriately More [)ro[cssion- al instruments might have more exotic capabilities such as re-mapping the keyboard or other com rollers onto different MIDI channels, but you'll learn about those things as j^ou go along. MIDI can be dealt with at a fairly low level for the beginner, yet it offers the capability of be- coming as complex as you like. A good place to start learning is "AH About MIDI" in the August 1989 Issue of Radio^Elec- tronics. And for a really well done treatment of MIDI (not only the technical details but also the user side of it), try read- ing MIDI for Musicians by Craig Anderton. published by Amsco Publications, r-e ?5 JO J} 9 m a a 2B A Shocking Offer! Now for the first time in CIE's 56 year history you do not have to be enrolled at CtE to recefve our Efeclronics and Electricity Lesson Modules. 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Please note thai unaulhorized wire and electronic oommynicaitons interception and intercapiion of oral commymcalions is itiegal under Federal and State Law In adCiilion Federal Law renders illegal ttie intefitional manyfadunng. a^semb^ing. possessing, or seltmg any eiectrorMC. mechanEcaL or other dtvice. knowing of {saving reason to know ifyt tue de$ig^ of such device renders it pnmanly useful tor the purpose of surreptitious mtefcep- tioR or wire, oral, or electronic commu- nications Federal law imposes both civil and criminal penalties for violations of the applicable statutes. Ttius. the use of the Scanner Converler described in this article is intended for and should be re- stricted to educational, scientific, and'or intormalional purposes, This is not in- tended to constitute Fegal advice and readers are advised to obtain indepen- dent advice as to the propriety of their use thereof based upon their individual circumstances and jurisdictions SCANNER CONVERTER We'll be converting those 800—1000 Af Ajfz signals down to 400—500 AffH| in no time at all. WILLIAM SHEETS and RUDOLF R GRAF WB Al^i: IN THE MIDDLKOF BUILDING our scanner converter — Us a device that allows ihe reception of signals from 800-1000 MHz on any scanner that cov ers fre- quencies in the 400-500 UHz range. Last month we dis- cussed the scjinner converter's circuitr)^. This month we are go- ing to build the unit and get it working properly, Constructioii If you are going to make your own' PC board from tlie Toll pat- terns vvcVc provided* you musl use G-10 type l^C materiaL '/m- inch thick, with a dielectric constant of 4.8, There's nothing inherently special about the common material except that the printed inductors and iiltcrs were designed around it. If other PC-board material is used, the printed inductors and filters vv^ill not have the proper electrical characteristics* Be- cause of the high frequencies invoh^ed, don't substitute com- ponents or change the layout. Also, when drilling the lioles fn the board, use the soldcr-slde foil pattern as a drilling guide, and drill through any hole you see even if you don't sec one on the component side. The parts layout is shown in Fig, 1, Note that a piece of wire must be In- serted and soldered on both sides anywhere you see an "X'' in Fig, 1. The resistors should be in- stalled while installing all jum- pers, which are made from component'lead clippings. To ensure solid grounding, all components that have grounded leads, especially the trimmer capacitors, must be soldered top and bottom. Coiis L7. L8, and L9 are made from #22 enameled wire wound tightly on an 8-32 screw. See the parts list for coii-vvinding de- tails. Coil L16, as shown in Fig, 2, is only a loop of wire and not at all critical and L6 and L15 are simply ferrite beads placed over a length of wire, also shown In Fig. 2. Coil L14 is similar, al- though this time a ferrite bead is placed over one lead of R20, again as shown in Fig, 2. Coil FIG. 1 — PARTS LAYOUT Note that a piece of wFre must be inserted and soldered on both sides of the board anywhere you see an "X." The chip components mount on the solder side as shown in Fig. 3. TP3. You should see around + 12 volts ±0.5 volt. Ifnot. Vmd the problem before proceeding. Check your work for shorts, sol- der bridges, missing solder con- nections, etc,, and then install the remaining semiconductor devices, observing the polarity on all of them. Watch Lhe lead configurations of ICl and Ql: once soldered in, they are diffi' cult to remove without damag- ing Ihem. Keep all coaxial leads going to the I^C board ver>^ short. Solder them to the board as shown in Fig. 4 for best operation, Ttie two slide switches (SI and 52) must be ganged together You can use the method shown in Ftg. 5 or devise your own. The converter board can be L13 is an RF choke and should have a ferrite core for a high "9 " value. Slide switches St and S2 should be mounted verj^ close to the PC board, with leads Vs-inch or less, measured from the top surface of the PC board- Mixer MODI is a prepackaged diode bridge balanced mixer: the blue dot on MODI indicates pin 1. Note that ICl. Ql, and all chip capacitors are installed on the solder side of the PC board as shown in Fig. 3. However, do not yet install iCl or QI-QS. You can install the chip capacitors after all regular capacitors are installed on top of the board. Install IC2 and D1-D3. Now connect power ( 12 VAC or 15—25 VDC). place S2 in the"on"posi- FIG.3— components tC1,Q1, and all chip capacitors are installed on the solder side tlon, and connect a voltmeter to of the PC board. Note how to position Qi and how to ground XTAL1. WIRE THROUGH MAKE HAIRPIN LOOP AROUND V^" FORM. RftSS ONE LEAD OF R20 THROUGH Fi RBITE BEAD REMOVE FORM AND INSTALL LOOP IN PC BOARD. FERRfTE BEAD-INSTALL IN PC BOARD. 42 FIG. 2 — COILS L6 AND L15 are ferrrte beads placed over a length of wlre^ L16 is just a loop of wire, and L14 is a ferrite bead placed over one lead of R20. WRY SHORT CENTER COMOirCTOR SHIELD STRIP, Tiw mn SOLDER TO GMDfOlL PC BOARD F!G- 4— ALL COAXIAL LEADS going to the PC board must be kept as short as possible. Solder ttiem to the board as shown here. mounted in a case with enough room for a 12-volt transformen You can also mount the board inside an exist inf^ scanner. If + 15 volts at 100 mA is available. If you have a regulated * l2-voll supply, you can use it for power by connecting the -»- 12 volts to the junction of C32. C33, and S2-b — in this case you can omit IC2. C34-C36, and D3 from the circuit. Figure 6 shows the inside of the completed pro- totype. Tune and align To align the scanner convert- er you llneed a VOM; a 100-MHz j— ^ CONVERTER CONVERTER OFF WRAP WIRE 2-3 TIMES AROUND ROD AND SOLDER (4 PLACES^ \ ACTUATOR ROD 6" LONG ON DRILL V^' HOLE mU fNSTALL VrflyBBER GROMMET GROMMET ROL£ SWING APFROX. 3'/ir NOTE: ACTlMJOft ROD SHOWN mnXTED 90* mMmSIMXEDPOSniOlt FORCLAfllTY WIflE FnS IN SROOVE NOLDSGftOMIO TIGHT TOROfi PC BOARD fTOPt PUSTIC CAP F^ONT RANa GROMWET ¥ns AROUWD SWrrCH BUTTOH i2 PLACES) m t2 PLACES) [1 y FIG. S-^ACTUATOR ROD SI S2 CONSTRUCTION. The two slide switches (Si and S2) must be ganged logether This method uses a brass rod or coat-hanger wire and rubber grommets. You can also devise your own method of ganging them together. or higher frequency counter and a non melallic scrcwdriven Preset all trimmer capacitors as shown hi Fif*. 7. and sel the slugs halfway in L7. L8. and L9. First check all wiring for shorts, opens, and correct com- ponent orientation. Then con- nect either + 14 -volts DC or 12- volts AC to the power input and check for ihe following voltages: • Junction of CI 6. L6* and R20 for - 12 volts ±0.5 volt • Source of Ql (the junction of C4. C5. and R3J for + 1 to -K 2 volts • Drain of Ql (tlic liot side 08) for ^ 10 to +11 voUs • Gate 2 ofQI (the junction of Rl and R21 for +1.5 io +2.5 volts • Output of ICl (the junction of R5 and C 12) for ^ 5 volts ± 1 volt • Wiper of R7 for + 10 to + 15 volts (van- the setting of Rl) • Junction of R8 and Dl for 10 to * 15 volts • Emitter of Q2 for +1.5 to ^3 volts • Collector of Q2 for + 10 to + 1L5 volts • Collector of 93 for +8 to + 12 volts • TP2 for - 1 to ^ 1 volt Do not proceed any further until those voltages are ob- tained. Slight variations out- side the stated ranges might be acceptable* but any major ones should be investigated. T^ble 1 gives some troubleshooting hints. Couple a frequency counter to L7 using a 2-turn wire loop as shown in Fig. 8. Set R7 in the center of its range and adjust L7 for a 50-MHz reading. Var^^ R7 and see if you can obtain about ± 1-kHx variation. Use the non- metallic screwdriver. Couple a frequency counter to L9 using a 2'turn loop, and con- nect a VOM between TPl (nega- tive lead! and TP2 (positive lead). Adjust L8 and L9 for max- imum voltage reading, which should be between 2 and 3 volts. Check to see that your counter reading is about 100 MHz. Make sure that you have set trimmer capacitors C25. C26. and C27 according to Fig. 7 for coverage of either 800-900 or 900-1000 MHz. Connect a volt- meter to TP2 and adjust C25, PARTS LIST O CZ5,C2 a scmHK:r tuninl in the viclnilv of 500 MHz (470 to 530 MHz will do). Now, sel the scanner In a "search" mode so as to gradually tune from the low end to the hi^^h end of the range. Find a huI table signal to align the F^F stages. If you have access to a signal generator in LED1— green light-emitting diode (optional) LED2— red light-emitting diode (optional) Inductors L1-L5, L10-L12'-part of PC-^board etching L6, L15 — ferrite bead on wire jumper (see Ftg. 2) L7— 0.2-0.32 |xH {9V2 turns #22 enameled wire wound on 8-32 screw with ferrite slug, Cambion part # 515-3225-06-21-00) L8, L9--0.05-0.1 fxH (314 turns #22 enameled wire wound on 8-32 screw with ferrite slug, Cam- bion part # 515-3225-06-21-00) 113— 1.0 juiH RF choke L1 4— ferrite bead over iead of R20 {see Fig, 2) L16— y2''turn #22 enameled wire on V4-inch form (see Fig. 2) Other components J1, J2— female 8NC connector MODI— MCL SBL-IX mixer module S1, S2— DPDT PC-mount slide switch XTAL1--50-MHZ 3rd overtone crystal Miscellaneous: PC board, smatl- diameter 50-ohm coaxial cable, project case, 14.5-24-volt DC or 12-volt AC, 350*mA transformer (see text)^ hardware as required, brass rod or wire^ two Vl;-inch rub-^ ber grommets, line cord if re- quired, solder, etc. Mote: The following items are available from North Country Radio, PO Box 53, Wykagyl Station, New Rochetle, NY 10804; • Converter kit including all parts except case and trans- former— $67.50 -f S3.50 S&H • PC board oniy— S13.50 i $3.50 S&H • Transformer— $9.50 y S3,50 S&H New York State residents must add appropriate sales tax. the 900-MHz range, use it (con- nected to Jl ) as a signal source. On a weak signal, peak CI. OB, C9, C13. and C!4 lor best signal-to-noise ratio. If you use an off-the-air signal, the signal may disappear before you are through- Do not mistake a stray 470-530 IVIHz signal that may leak into your seamier for 900 COMPONENT SIDE oi the scanner con- verter board. Board shown half size. ^•o i ■ ■ g ■ hi", ■ ■ SOLDER SIDE of the scanner converter board. Board shown half size. MHz. To check this, turn off the converter using the built-in switch. If the signal Is false, it will get stronger. If it is a real 900-MHz signal, it will disap- pear when the eon verier is turned off. You can re-peak the converter at any time on any part of the frequeney range. Typical RF bandwidth is 40 MHz at the 3 dB points. Signals will be heard 10 to 20 MHz beyond those limits, so if you use the converter ton sav 800-825 MHz and 851-868 MHz (most com- mon}, you can peak the convert- er in the middle (825 MHz) and still get satisfactory perfor- mance. It is possible to "stagger tune" the circuits to increase bandwidth, although you will lose some gain. R-E Earn Your B.S. Degree in ELECTRONICS or COMPUTERS By Studying at IHome Grantham College of Bagioecring, now in our 41st year, is highly ex- perienced in "distance education'' — teaching by correspondence— through printed materials, computer materials, fax, and phone. No commuting to class. Study at your own pace, while continuing on your present job. Learn from casy4o- understand but complete and thorough lesson materials, with additional help from our instructors. Our Computer B.S. Degree Pro- gram includes courses in BASIC, PASCAL and C languages — as well as Assembly Language, MS DOS, CADD, Robotics, and much more. Our Electronics B.S. Degree Pro- gram includes courses in Solid-State Circuit Analysis and Design, Control Systems, Analog/ Digital Communica- tions, Microwave Engr, and much more. An important part of being pre- pared to move up is holding the right college degree, and the absolutely neces- sary part is knowing your field. Grantham can help you both ways — to learn more and to earn your degree in the process. ^ Write or phone for our free§. catalog. Toll free, [-800-955-2527, or^ see mailing address below. fS g. Accredited by o Ihc Accrediting Commission or the m National Home Study Council g • I GRANTHAM ^ College of Engineering Grantham College Road 45 Slidell, LA 70460 6 46 Electronic Temperature Measurement What is temperature and how can it be measured electronicailyZ TEMPERATURE IS PERHAPS THE most common of all physical measurements. From weaiher forecasts to industrial pro- cesses to patient monitoring, its measurement perv^ades our lives. Yet, unless our jobs di- rectly involve temperature mea- surement, most of us don*! give much thought to what Icmpern- ture is or how it stneasiired. in this article we will look brietly at how temperature is defined and survey the field of electronic temperature mcasuremenL. We'll then begin an in-depth study of temperature sensors and application circuits, clos- ing with a look at nonconlact infrared thermometry. What is temperature? Any grade school science dent knows that heat is mo- lecular motion. The hotter something is, the faster its mol- ecules move; absolute zero is de- fined as the point where all mo- lecular motion ceases. All well and good but, since we canl see molecules move, how do we measure temperature? The bedrock standard used by the NIST {National Institute of Standards and Technolog>\ formerly the National Bureau of Standards) is based on the per- fect gas law The law states that as temperature rises, either the pressure or volume of the gas HARRY L. TRIETLEY must increase in proportion. Mathematically. P x V - WW where P = pressure, V - v{>l ume, T - absolute leiiipera- lure. and k is a const^iiii. Doubling the nioierulai \ elocrity in a consent volume results in twice as many molecular colli- sions per second, or twice I he pressure. At absolute zero a per- fect gas w^ould collapse to zero volume and pressure, F'igure I illustrates the con- cept of a constant-volume he- lium gas thermometer. (Perfect chan^ the ntCTriscus surfnte, limits measuremej accuracy. On top of all that, rections^iusl be made fori Hum's d?^Liations frorn^/fhe perfect gasT^i Th< re fo^ef gas- law thermometry is used pri- marily by national standards laboratories such as the NIST. Temperature scales Companies and lah^^torte!^ which nianufacture%Tealibratc Iherinuiaeters need a more urn EF^^ gases do not exist, but heUum I2|:actfeal standard. For that rea- comes close.) A mercury' m ometer — a device used for me a' suring the pressure of gasses and vapor^j^with an adjustable resj&i-^Oif measures the gas pressure of a helium-filled bulb. As temperature changes, a plunger in the reservoir is ad- justed to maintain the left leg of the manometer at a constant height., thus maintaining the helium' at a constant volume. Wtien a vacuum is pulled above the right leg, the mercury height indicates_Jlie'gas. pres- sure, and thus the"temperature of the helium. The concept sounds simple, but precision measurements are difficult. Temperature- af- fects the volume of the bulb and the interconnecting tube is not at the same temperature as the bulb. Also, the relatively small , \hv International lempera- turc Scale (ITS) was estab- lished. Previously known as the International Practical iernper- ature Scale to dislitiguish it from the fundamcuuil gas- law scale, it is regularly reviewed and revised bx-interriat ioiial conferences inTOlving a nuEnber of national standards laborato- ries- The latest revision* pub- lished in 1990, is known as 1TS*90. The scale begins wiih aperies of agreed-upon fundamental temperatures, or hxed poinis. The freezing (or melting) point — or, in some cases, a vari- ation known as the tripl point — of certain high-purity materials have been assigned precise temperature values by agreement among the par- ticipating labs. Figure 2 shows a typical fixed-point cell, A graphite crucible conlainin^J a high-purily metal is sealed in a quart/, envelope filled with ar- gon or some otiier inert gas. Table 1 lists several fixed points. The freezing point of sil- ver for example, has been as- signed the value of 1234.93 - Kcivin (absolute) or 660.323 de- grees Cefsnrsv Waters triple poiiiL which can be controlled more preciselv tlian the freezing point, Ls defined to be 273.16k orOJ>l'C:, (The triple point is like the freezing point, except ttial ihc ni^terial is sealed in an evaeu- glass container Instead of ^PBeing at atmospheric pressure, the water sees onty its own vapor fin^ssLirfe/'Slnce the freex- ing [jf)int \s a 11 re ted by both air pressure and eon I ami nation, the iriple poini is more repeata- , ble. The term, "triple point. * re- fers to the fact that the material is in tlirce-phase equilibrium — vapor, liquid, and solid.) To make the scale practicaHaife, is necessary to have scastir<^ thai can interpolal^'Beiwcen the de lined jilted points. ITS-90 defines several such sensors, ^gpovering various portions of tlie ^^cale. The "center" of the scale, be- tween the hydrogen triple point and the silver freezing point, is interpolated using higli-gratlc r t' s i s t a n e e I h e rin o tn c i c rs known as SPRTs (Suindard Platinum i^iesistanre Ther- mometers). SI^Rl^s are carefully constructed ofhigli-pnrity plat - " inum wire, wound and as:^ sembled with a minimum of support so as to be sLraia-fire^ Tiie thermometers arc calli brated at three or more fixec| points, then used be i ween those temperatures. Their H versus T equations are very complex and must be handled by computers. Figure 3 shows a SPRT enclosed in a.^^yex sheath, '^/^F The very low end of tfee ^^cale, down to 0.65K. is defined by He- liimT i*as'law t liermometn': Sev- era! overlapping ranges are de- fined, each with its own set of ^ implex equatlO[is and tables. At the high end. temperatures above the silver freezing point are defined using radiation thermometiy. Well look at radi- ation thermometr^rnexl month, but l^asically it makes use of the fact that infrared or optical radi- ation increases with tempera- ture. (The older IPTS also used thermocouples made of plati- num alloys to define part of the temperature scale, but this was dropped in the 1990 revision.) Commercial sensors For the balance of this article we'll c*xamine and compare eomuKTrial temperature sen- sors|j,thcrmoeouples. resistance iheiitifHiieters* thermistors* and siiiron ^C) sensors. Let's begin with a qtriek sur\Ty: Hible 2 en m pa res their charac- teristics, while Fig. 4 shows op- erating ranges and accuracies. hicidenlally. for a lirsi-rale mail-order source of tempera- ture sensors, instrumcnls. ahd infnrmatfon coniaet Omega En- gl net Ting, One Omega Drive, Box 4047, Stamford. CT 06907. J*80(J-B26-6342 tCT and inter- national. 203-359-1660), Tiiermocouples are nothing more than two dissimilar met- als joined together. When con- nected* an EMF is produced which increases (approximately linearly) with temperature. The thermocouples sensiLivily, lin- earity, and teniperatitrc range depend on the metals used* Over the years s< vei"nl types of thermocouples have enuTgctl as standards. In the US the NIST publishes m ill ivqlt- vers us- tem- perature tables C6r eight types* identified by le|ter codes. Five (types J, K, T E. and t^. made from base -metal alloys . cover varying teniperai u re nmges and application^ Sensitipties are t>7>ically terfs of micr^'olts per degree C. me other ll^ee (types R, S* and p} are formed of plati- num anc^ platinum ^iloys. Ob- viously expensive, tfiey are the most stable and r^eaiable of thermocouples, and most often used for high-temperature work, but their sensitivities are lower. Thermocouple wire and probes made to these standards are av^aitable from a number of manufacturers and dis- tributors. In addition » some manufacturers produce special tJiermocouples for high temper- ature, endogenic, and other spe- cialized applications. Most com- mon of these are tungsten alloy thermocouples which ailow measurements as high as 2315'C (4200T1. A resistance thermometer (commonly called an RTD* or Resistance Temperature Device) consists of a coil of fine-gauge wire or metal film. Most metals change resistance with temper- ature, but platinum or nickel are most often used to make RTD's. RTDs generally are more stable, accurate, and sensitive than thermocouples, but are limited to lower temperatures. Platinum RTDs are the most stable and accurate and cover the highest temperature range. Nickels lower cost has made it attractive for moderate- temper* ature industrial applications: however, recent advances in the art of manufacturing platinum- film elements [similar in princi- ple to metal-film resistors) has eliminated the cost advantage of nickel. Other metals, pri- marily copper and an alloy named Balco, are sometimes used as well. Thermistors are probably somewhat familiar to most readers. Unlike thermocouples and RTDs. they are highly sen- sitive, higiily nonlinear, and cover limited temperature ranges. Positive temperature coefficient (PTC) thermistors exist, but those best suited to temperature measurement are negative temperature coeffi- cient (NTC) devices which de- crease in resistance by about 3 to 5% per ''C. Thermistors ofTer the widest variety of sizes, shapes, accuracies, and prices of any commercial temperature sensors. Integrated circuit {ICl temper- ature sensors are newest and easiest for most experimenters to apply. They are sensitive and linear, and interface easily to op- amps and A/D converters. On the flip side, IC*s have not be- come as standardized as other sensors. Precisely-calibrated (selected) grades tend to get ex- pensive. Their temperature range is about the same as ep- VACUUM \ PLUNGER FfG. 1— CONSTANT-VOLUME GAS THERMOMETER. The plunger is adjusted to main* tain the left leg of the manometer a! the index line as the gas pressure changes. TABLE 1 Fixed Point Hydrogen Triple Point Neon Triple Point Oxygen Triple Point Argon Triple Point Mercury Triple Point Water Triple Point Gallium Melt Point Indium Freeze Point Tin Freeze Point Zinc Freeze Point Aluminum Freeze Point Silver Freeze Point Gold Freeze Point Copper Freeze Point oxy-coated thermistors. Which sensor is best? It depends upon temperature* application and accuracy. At high temperatures thermocou- ples may be I he only choice* Best accuracy generally is given by platinum RTDs, although precision thermistors may excel near room temperature. Ther- mistors, because of their high sensitivity, are superb in nar* row- range applications such as Temp (K) Temp (X) 13.8033 - 259.3467 24.5561 -248.5939 54.3584 -218,7916 83.8053 - 189.3442 234.3156 -38.8344 273.16 0.01 302.9146 29.7646 429,7485 156.5985 505.078 231.928 692.677 419.527 933,473 660.323 1234.93 961.78 1337.33 1064.18 1357.77 1084.62 medical thermometers. Ther- mistors and ICs both sen^e well for moderate accuracy measure- ments and temperature com- pensation applications. ICs and. to a lesser extent. RTD's offer limited package se- lections. For small size and fast response* glass*bcad ther- mistors are available In diame- ters from 0,014 down to 0,005 inch while uninsulated ther- mocouple wire is available down to0.0005-inch diameter At the other end of the scale, ther- mistor washers and discs are of- Tered with diameters up to 1 Inch. Thermocouple wire is available to 14 AWG and even larger, with insulalions ranging from PVC io i cram it* libers or beads. Surface temperatures may be measured by ribbon- slyie tberni(n'OUpl(\s. or Iher- mncouple win*s may be welded dirtH^ly lo metal surlaees. Now thai our survey is com- plete, let s look at each in detail. IC sensors Fonvard-biased silicon diodes and base-emitter junctions have often been used to mea- sure temperature. At room tem- perature, a forward-biased FIG, 2— FIXED POIJ^T CELL. The graph- ite crucible, visible through the quartz enclosure, contains a high-purity metal, (Courtesy of YSI Inc.) TEMPERATURE {^C) FIG. 4— THE "BEST' TEMPERATURE SENSOR depends on the temperature range and accuracy required. FIG. 3— STANDARDS-QUALITY SPRT, assembled into a quartz sheath. (Courtesy of YSI Inc.) junclion drops about 0.7 volts, with a negative temprriitvirr co- efficient of approxitiiatcly -2mV/%:. The exact voltage and temperature coefficient de- pends upon tlic junctions ge- ometry, current densily. and other factors. Precise calibration requires individual ineasurernent of each diode or transistor at known temperatures. The basic equation for a P-N Junction is: l = f f qv where q is the charge of an elec- tron, k is a physical constant known as the BoUzinann con- slant, and T is the absolu te tem- perature (Kelvins). Iq is a TABLE 2— SENSOR COMPARISON CHART Sensor Type Typical Temperature MIdrange Non- Sensitivity Range Accuracy Linearity Base Metal Thermo- 40 to 70 -270 to 1.1 to 1 to 5% couples Types J. K. X N 2.2=C Platinum Alloy Thermo- 7 to ta -50 to 0.6 to 1 to 5% couples Types R, S, B 1820'C 1 .5^^C Tungsten Alloy 10 to 21 -17 to 2 to 7% Thermocouples 231 5^C Platinum Resistance QAiirC - 200 to 0.1 to 1 to 3% Thermometers { 1 0Oilj 650'C 0.25"C Nrckel Resistance 0.7!>/^€ -60 to 0.4°C 1 to 5% Thermometers (1000) 180^C Precision Disc -3 to - 5 -80 to 0,1 to Inherently Thermistors %/*C 150^C Nonlinear Glass Bead -3 to -5 -60 to Nontnter- Inherently Thermistors %rc 300^0 changeable Nonlinear Integrated Circuit 1 p-A/'C or -50 to 0.5 to 0.3 to d^'C Sensors 1 to 10m VAC 150'C 5°C constant, basically equal to the reverse -biased leakage current. At room temperature, the quan- tity kT/q IS about 26 mV. Under normal fonvard-biascd condi- tions the - 1 term is insignifi- cant and can be ignored » so: qV lerenee between two base-emit- ter vohage drops where the junction currents are main- tained at a constant ratfo. 12/1 L Applying a little algebra to that equation shows that the voltage difference is given by: {\2) kT V,-V,=-ln SO In In I I = v An IC temperature sensor's operation is based on the dlf- Circuits within the IC use that difference to create an output voltage or current whicti is pro- portional to temperature. Table 3 lists four IC's, The AD590 and AD592 behave iden- OR mm TEMPERATURE SEMSOR Rt I.OOOK ImV/K PIG. 5— AN AD590 OR AD592 makes it easy to transmit temperalure data over a pair of wires. The circuit produces ImV C ( or ImV F using the values in parentheses). LM3S R1 fl4 C2^ LOW-PASS 100K 0.0% FILTER T"^ j I 1 C3 0.1 X*- SWITCHED ^. CURRENT +^ec SOURCE I *C1 0.1 T J 1 T '^compaSator"*n^/*""1 ici m m I IcURRBifST" SWrTCHED V0L1WE H REFOtfl^ 1.9V LIW 3J1 I 1 J 1 I ONESHOT I rR6 IK +fiV - — ^"*^5/ B5 J. C4 6 W Jo.001 FIG. S— AN LM35 OR LM34 PLUS A V/F IC produces a frequency proportional to lemperature. TABLE 3— TEMPERATURE SENSORS Available Available Type & Mfr Description Ranges Accuracfes AD590: Analog Two terminal -55 to 1.7 tolO^C Devices. Hams current source (0,5 to 5=C (a 25'C} AD592: Analog Two terminal -25 10 lOS^C 1 to 3.5"C Devices current source (0.5 to 2.5^C t^AK 6/ 0 to LM34, Lf^35: Three terrT^mal -55 to I SO'^C 1510 2X National current source (0.5 tore m lOmV/^F (LM34) (a 25X) lOmV/^C {LM35) LM1 35/235/335: Two terminal -40 to 100X 2.7 to Q'^C ■ National voltage regufator -40 to 125"C (1 to 6"C 10mV/K, -55 to 150^0 (ii without catibratable user calibration tically* but the newer AD592 is less expensive {plastic TO-92 cascK covers a narrower range. and, over that range, offers tigliter accuracy. Nationals LM34/LM35 is a three- terminal device having zero output volt* age at O'T or C, while the LM 135/235/335 is a Zener-like device with an output propor- tional to absolute temperature* Lei's start with ilie AD590/592. The AD590 and AD592 are I wo- terminal cLirrcni regulators with an output of 1 ^A/K (273.15 fxA al O'^C), Calibrated by thr iiianiUiifturf r at 5 volts, upciation is guaranteed rrom 4 to 30V Keep in mind, though » that raising the voltage in- creases internal power dissipa- tion and leads to slight mea- surement errors. Figure 5 lit usl rates their use in a simple circuit providing DVM temperature readout in C or E Ttae 1 \uVK current passes through Rl. which converts it to voltage with a sensitiviiv of 1 niV/X (l.OOOK) or 1 niV/' F ( 1.8QQK). The voltage across Kl is proportional to absolute tased on 1 mV/degree. (Sugges- tion: place the IC in a closed-end sheath and let it come to equi- librium in a stirred ice-and- water bath. Trim Rl until tlie voltage across it is 273,2 at Q^'C J LM35 1 rsv + DVM READOUT: nomvrn be? r FIG. 7— A NEGATIVl BIAS is needed for readings below zero degrees. FIG, a— A BROAD VARIETY Of Ihermistor styles ar^ available. Shown here are some of the more common ones. TABLE 4^THERM1ST0R CHARACTERISTICS Thermistor Available Type Resistances Low Cost 100 ohms to 200K Precisron 100 ohms to Interchangeable 1 megohm Disc Glass Bead 200 ohms to 1 megohm Glass Coated 2.2K to Interchangeable 30K Disc or 49 L 7 mV al 32°F.) Adjust R3 as described earlier. The AD590 is available In sev- eral grades from ±5°C (AD59bj) to -O.S^C at 25X (AD590MJ, The AD592's guar- anlccd 25''C accuracies ratige from (AD592AN) Lo Mid-Range Typical Accuracy Temperature Range 5 to 20% - 50 to ISO^^C (1 lo S^C) 0.1 to 0.2"C -80 to 150X (0,5 to 1%) 20% -60to300'C (5X) 0.05 to 0.2'C -80 to 250X (0 2 to 1%) ± 0.5^C (AD592CD). The AD590 is available in TO-52 transistor can or flat-pack enclosures^ while the AD592 is sold in a TO-92 plastic iransisior pack- age. Both are sold as un- packaged, trimmed chips. Nationals LM34/35 series is even easier to use. A three- ter- minal IC. it outputs 10 mV/^F (LM34) or 10 mVrC (LM35) and is zero-based (zero millivoUs at zero degrees K All that is needed to read temperature is a DVM and a batten^ or voltage source (anv^vhere from 4 to 30 volts). Figure 6 combines an LM34 or LM35 with an LM331 voltage- to-frequency converter lo pro- vide a frequency proportional to temperature, the componeni values shown produce an out- put of 100 H/Jdegree ( 10 kHz at lOOT or CI For more informa- tion on the LM331 and other V/F conveners see "V/F Converters/" Radio-Electronics < June 199 L As wilh the AD590/592. no lemperatuiH^ (^:ilil)rtttion is nec- essar>^. Ih r:ihi>rate it, you tem- porarily dijsetjnnecl the sensor, provide a precise 1,000 volt in- put, and adjust R3 for 10.00- kHz outptil. No zero adjustment is netessar\* For improved ac- ctiracy using loose-tolerance IC s, you can place the IC al an accurately- known temperature near the high end of its range and adjust R3 for the proper output. The LM34/35 needs a nega- live bias to track temperatures below zero. Figure 7 shows the basics: the IC is pov%'ered by a positive supply, but a negative bias current of approximately 50 ^A is added to tlu^ output. The LM35 is available with temperature ranges of -55 to 150"C, -40 to llO^C (sullix C), and 0 lo 100"C (sulTix D). and wilh 25''C guaranteed ac- curacies of ± rc and ±0,5X (suffix A). Similar grades are available lor the I.M34 Fahren- heit version. Packages are TO-46 metal and TO-92 plastic. The last IC in the table is Na- lional's LM 135/235/335 series. The LM135 operates as a Zener-like two- terminal voltage regulator IC. similar to an LM185 reference, A third termi- nal allows a potentiometer to be added for user calibration. The bias or "Zener" current may be amwhere from 400 jxA lo 5 mA. Us output is proportional to ab- solute temperature, 10 mV/K (2.73 volts at O^C). The lightest 2BT guaranteed accuracy without user calibra- DIGITAL VIDEO STABILIZER EUMtNATES ALL VIDEO COPYGUAROS al movies, yoy will notice annoying pe- riodic color darken- ing, color shifts unwanted lines, flashing or jagged edges. This is caused by the copy protection Jamming signals embedded in the video tape, such as Macfovision copy protection. t>he DtQiTAL VIDEO STABI* UZER; fOdi COAJPUmiLY ELtMliMATeS ALL COPY PROTECTIONS AND JAM^ MINQ SIGNALS AND en]l«35 YOU CRYSTAL C<£Af^ PICTURES. 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Themustors Negative leiii[>eratiirc coeffi- cient (NTC) thermistors, the type best suited In temperature measurement, arc narrow- range, highly sensitive, non- linear devices. Resislances at 25'*C can run from under 100 ohms to 1 megohm and beyoncL Topical sensitivities are -3% to -5%rC. Thus resistance changes from tens of ohms to tens of kilohms per "^C are possi- ble, NTC thermistors are formed from mixtures of powdered met* al oxides, usually nickel and manganese oxldt^s with others sometimes added, Tlie powders are blended with water and binders into a clay-like slurr>\ pressed into the desired shapes (disc, rod, washer, etc.] and dried. The dried thermistors are then fired fsintered) at tempera- tures above lOOOT to form a re- sistive, ceramic-like structure. Figure 8 illusl rales the great variety of Ihcrmislors available. Most common Ibr temperature measurement applications are epoxy-coaled dist^s. generally under 0,1-lncli iti diameter Similarly-sized glass-coated discs perform at higher temper- atures. Bead thermistors, both glass-coaled and bare, offer small size and last response. Sizes var\' from around 0.05 inch down to 0,005 inch. At the other end of the spectrum, ther- mistor rods are available as well as disc and washer shapes up lo l-inch diameter In addition, several man ufac Hirers offer thermistor sensor asscml:)lies ranging from slraighl-stick probes to bolt -on and surface- mount assemblies to transistor cans. Specifications vary greatly, but Table 4 summarizes several ty|)es. Thermistors liave a repu- tation of being not loo accurate or stable — and thai is true of most inexpensive devices, T\'p- icai resistance tolerances at 25*C are between 5 and 20%. corresponding to 1 to 5^C ac- curacy. The tolerance loosens at high and low temperatures. At least three companies (YSI in Yellow Springs OH, Fenwal in Milford MA. and Ther- mometries in Edison NJ) offer precision interchangeable disc thermistors (cpoxy coaled}. Covering the range from - 80 to 150'C, loosening to about VC at the high and low extremes. Pre- cision and stability are achieved by grinding the discs to precise values in tightly-controlled tem- perature baths and by aging tests and individual measure- ments. The 25X resistances range from 100 ohms to 1 megohm* but one value (2252 ohms at 25°C| has emerged as a quasi- standard for use in medical and laboratorj^ thermometers. Com- monly known by YSIs "400 Se- ries" designation, it is available in a wide variety of probe styles. To illustrate how sensitive ther- mistors are, the 2252-ohm de- vices are 1.66 megohms at - 80^C and 41.9 ohms at 150X. Small glass beads are formed somewhat differently, A pair of high-temperature wires 1 typ- ically fine-gage platinum) is coaled with a droplet of the slur- ry; fired, and then dipped Into molten glass. The result is a high-lempcralure device which typically is more stable than ep- oxy-eoated discs but which can- not be ground or trimmed. For precision applications ther- mistors may be supplied by the manufacturer with individual test measuremenis. For inter- changeability, the manufac- turer may select and preassem- b!e two thermistors in parallel lo match a specific calibration cun e. Glass beads generally are specified to about SOOX, Next month we'll look at some ihermistor application circuits, then mov^c on to resistance ther- mometers and thermocou[jles. Wc will conclude with a look at noncontact radiation thcr* mometry. If you want to study thermistors in detail, look at Radio -Electronics' three-part series, "All About Thermistors," Januarys — March 1985. R-E aRCL£ iSa ON FHEE INFORMATION CAR& iriTELLiGEnT PHonE-LinE moniTOR zzzmn THOMAS E. BLACK Log telephone/modem/fax usage automatically and inexpensively with our intelligent phone-line monitor. RliSOLVING MONTHLY TEI.BPHONK bills can be a slruggle, es- pecially in a shared household. It seems that there are ahvays some long-distance ealls that we would like to dispute (did some- one really call Oshkosh. Wiscon- sin?) One solution is lo main- tain a telephone log on paper, but doing so requires personal discipline that may be hard to keep up. Managing telephone usage is a problem that extends into the office, too. Knowing how long you spoke lo each call- er is a necessity if you bill for your time. If only one could log all phone calls automatically! As a matter of fact, there is: Digi-Call (Digital Call Auto-Log- ger), This unobtrusive device can solve your telephone-man- agement troubles. DJgi-Call is a microprocessor-based system that connects to any standard telephone outlet and passively waits for incoming or outgoing calls. When you make an outgo- ing call. Digi-Call silently logs the time, telephone number, call length, and other vital infor- mat ion. When you receive an in- coming call, Digi-Call records the time, call length, number of rings before answering, and more. A four-digit account-cod- ing system optionally allows you to associate each call with a par- ticular client, user, or house- mate simply by pressing the appropriate code any time" dur- ing the conv^ersation. Digi-Call can work with both rotary and Jbuch-Tone phones, but the ac- count-management feature is available only on tone phones. Digi-Calls intelligence is pro- vlded by an 8-bit micro- processor, 32K of RAM, and 8K of EPROM-based realtime soft- ware. Digi-Call s internal RAM allows it to record more than 1550 calls without user inter- vention: audible and visual 9 m 01 53 fcn aic + 5V p POWER ON POWER SUPPLY 9VAC INPUT IC4 8K EPROM ^ IC5 IC9 a031 B1 X BACKUP " BATTERy WATCHDOG STATUS RAM FULL n SI CONFieURflTlON S3 mm- IC2 DTMF DECODER ANALOG DiGiTAL TILEPHONE IMTERFiJ^CE !C3 MAX232 -o CIS -o RTS -O TXD RXD TO PKOME LINE SERIAL I/O FIG. 1— BLOCK DIAGRAM shows the three major sections of the circuit; the micro* processor and memory circuit, the phone-Une interlace, the power supply, and the switches, LED's, and speaker. alarms signal when RAM is tulK A rechargeable battery^ ensures that data will not be lost be- cause of a power interruption. A built-in serial inlerface allows all data lo be uploaded to a PC where sophisticated host soft- ware provides data analysis and reporting in a friendly* menu- based system with context-sen- sitive help screens. Data is stored in standard format for analysis by spreadsheet and database programs. A complete kit of parts is available for about $170: a com- mercial-quaUty PC board is also available, as are hard to find parts. All software is available from the author and the R-E BBS ( 5 16-293-2883. 1200/2400, 8N1) as a self-ex- tracting ZIP file called DI- GICALL.EXE. A brief summarj^ of Digi-Call's features is shown in Table L Circuit overview A block diagram of the circuit Is shown in Fig. 1. Intelligence is provided by 1C9, an 80C31. That popular 40-pin Intel device con- tains an 8-bit CPU, 128 bytes of internal RAM> 32 programma- ble I/O ports, two timer/event counters, serial input and out- put lines, and 64K address spaces each for program and data memory Telephone inter- face circuitry cleans up the au- dio and feeds it to DTMF (Dual- Ibne, Multi -Frequency) decoder IC2, which drives a parallel in- puL^'output (PIO) expander ICS. The line interliice also provides a digital interrupt signal so that the microprocessor will know when something is happening on the line. A MAX232 buffers serial inputs and outputs from the microprocessor and pro- vides RS-232 signal levels from a 5-volt supply: several lines from the PIO drive serial-control lines DTR (Data Terminal Ready! and GTS (Clear to Send). Miscellaneous functions per- formed by the 803 1 include driv- ing several LEDs for status indication, and monitoring the PWRON line from the power sup- ply. When there is a power out- age, the microprocessor senses and signals that fact both audi- bly and visually Support components include 1C4 and ICS, which provide 8K of program and 32 K of data stor- age, respectively A realtime clock (ICll) allows the unit to record time and data of each call TABLE 1— DIGICALL FEATURES • Stand-alone operation while recording calls • PC interface uses standard serial COM port • Turn-on chime reminder • Real lime clock • 32K buffer stores more than 1550 caEls • Built-in hardware diagnostic utilities • Battery backup with alarm • RAM full visual/audible alarm • Data sorting, formatting and printing features • Hardcopy and disk file mport output • Export feature compatible with many spradhsheet programs • Supports popular PC/XT/AT video formats, including 50-line VGA color • Account Group Recording (9999 accounts) • Total Cost less than $200 accurately: H also contains some RAM for intermediate data storage, and drives SPKFi The realtime clock {ICll). and the peripheral Interface (IC8J tC5--M5M5256A or HM62256LP-15, 32K x 8 static RAM IC&— 74HCT373, CMOS 8-bit latch IC7— 74HCT138, CMOS 3-tO'0 line decoder ICS— 82C55A. CMOS peripheral interface 1C&-^0C31 or80C32, CMOS microprocessor ICIO— 74HCT14. CMOS hex inverter IC11— MC148818A, realtime clock with RAM (see text) IC12— LM2940T, 5 volts. 1 amp, low-power fegulaior Other Components B1— 6 Nl'Cd AA Cells. 400-600 mAH PI— 6*pin, O.r header connector SPKRI^-ohms. IV^^ 51— 8-position DIP switch 52— SPST. normally open* mo- mentary, PC board mount 53— SPST, normally open, mo- mentary, panel mour^t XTAL1— 3.58 MHz, HC-18 XTAL2— 11.0592 MHz, HC-18 XTAL3-^.194 MHz. HC-18 M0V1— ERZ-C07OK201U. 130 volls, 400 amps. ZNR surge suppressor Miscellaneous: 6-cell AA battery holder, TO-220 heatsink, wail transformer (8-9 VAC, 300-1000 mA), PC board, IC sockets, er^- closure (8.25 x 6.25 x 2), modu- lar telephone line cord, assembly hardware, software- Mote: The following parts are available from Digital Products Company, Attn: Thomas E. Black, 134 Windstar Circle, Folsom, CA 95630: Complete kit of PC-board and parts with- out enclosure, SI 69.95; printed circuit board #DC001, S42.50; 75T204 DTMF decoder S14.50, programmed EPROM, S16.50, 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. share the upper t6K of the ad- dress space, as decoded by IC7, beginning at COOOh. Outputs of IC7 are enabled at lOOh inter- vals* Le., the realtime clock is addressed at COOOh, the PIG at ClOOh, and the remaining out- puts are unused. Current time and date are maintained by realtime clock ICll, an MCI 468 ISA, which also has a simple square-wave tone generator and 50 bytes of RAM. The RAM serves as a buff- er for incoming RS-232 data; Digi-Call uses the square-wave generator portion for audible signalling. The EPROM (104) contains all system code: it is accessed be- ginning at OOOOh whenever PSKN is low. Iblephone inteiface The key to Digi-Calls opera- tion is its telephone interface, shown in Fig. 3. Note that this circuit uses two separate grounds: analog and digital. Electrically they meet at a com- mon point near the power-sup- ply ground. To avoid noise problems, the two ground cir- cuits must remain separate ex- cept where they meet at the power supply (Our PC board en- sures that that is so.} Digi-Call determines the sta- tus of the phone line by watch- ing (he voltages present on it » A standard phone line sits at -48-volts DC when not in use (when it is on-hook). When the phone Is in use (when it is off- hook) the nominal voltage is about -7-vQlts DC, When the phone rings* a 90-volt, 20-Hz AC signal appears across the line. When you dial a number using a roiarj'-dial phone (or the puise-dlal option on a modern phone, modem, or fax ma* chine), what happens is that the device interrupts phone- line current, thereby causing line voltage to swing between the off- and the on-hook volt- ages* For instance, dialing the digit "9" causes nine oscilla- tions between the two voltages, usually at a rate of about ten pulses per second. Rather than Interrupt the flow of current, pushbutton phones usually send DTMF tones, which we will describe momentarily The telephone interface con- nects to the phone line at the tip 9 o 111 9 CTS DC W-DOG STAT RXD TXD RST 10 12 17 29. 1^ XTAL1 Pl.t XTAL2 P1-3 B0C31 \c POO/ADO PI. 5 P0.1/AD1 PI 6 P0.2/AD2 PI, 7 P0.3/AD3 RXD/P3.0 P0.4/AD4 FXiJ/r J,1 P0.5/AD5 mmpa.z P0.6/A06 1 H 1 1 / TsJ. J OA 7;An7 T0/P3J P2.o;a0 T1/F3.5 P2,1/A9 Wft/P3.6 P2.2miG RDy?3.7 P2,3/An PSEN P2.^/A12 RST P2.5/A13' GND P2.6/ATf EA ALE f^^^^Al^i ■rr XTAL2 11, 0592MHz C24 T'37pF 39 / 36 y X 8 35 y ^ 13 34 / ^ 1^ 33 y ^ 17 32 yK 16 \ 22 23 \ \ 24 2& \ 26 \ 27 \ 2S DO QO Dl 01 D2 Q2 D3 106 Q3 74HCT373 D4 OA m 06 D7 11 ALE Q7 OC 12 1^ V_6 16_/ ^ 19 25 24 21 23 20, 22, AO Al A2 A3 Al A5 AG A7 AB A9 A10 All A12 OE OO 01 02 03 IC4 04 27C64 PGf^ 15 16 19 1 XTAL3 4.194 MHz R30 10 MEG X C27T 27pFj_ 15*^026 ^5-35pF 10 RST iClO'd V« 74HCT14 OSCl 0SC2 ADO 20 CFS STBVlo AD1 rcn RES f^^2 (V1C146@1BA psj>^ 23 AD3 AD4 ADS AD6 AD7 MOT GflO SOW C0U7 IRQ DS fVW AS 24 ^19 17 15 \ 9 \ 8 \ 7 f \ 6 \ 6 \ 4 \ 3 \ 24 \ 25 \ 21 \ 23 \ 2 \ 26 DO 01 D2 m DA D& D6 07 AO Al A2 A3 A4 A5 m A7 ICS A9 HH52Z55 A10 All A12 AT3 AN CS WE> OP >^ F^EAO 12_^ 13 16 J9 WRITE R17 10KX9 26i 10 34 \ 33 . 32 \. 31 \ 30 29 28 27 5 36 .A9 Alp A14 11 IClO-e /6 74HCT14 10 NOTE: ^ = POWER SUPPLY 7 GROUND V = DIGITAL GROUND YO Ylfc> A B ^ IC7 Gl 74HCT13S Y3 V4 Y2|0^ 12 qG2A G2e 11 10 CC 8 / 35 FAO PAl PA2 03 ICS TO CS AO Al RESET mo m4 PAS PA6 m7 PBO PBl PB2 PB3 PB4 PBS PB6 PB7 PCO PCI PC2 PC4 PCS PC6 PC7 40 39 18 19 20 21 22 HI 3 \2 25 14 15 16 PC3i^ IL V O Q S2 OfF/SIArJDBY DTR 5 FIG. 2— DETAILS OF THE MrCROPROCESSOR/MEMORY CIRCUIT which consists of an 80C31 microprocessor, 32K of static RAM, and 8K of EPROM-basad realtime software. 56 J TIP LINE iRmG pi NOTE: mAlOQ GROUND OmnAL GROUND Ha TOOK I 1 M0V1 *--^t AS\ TOOK 04 lN414a 01 02 lN4l4a lH4l4e -2, OS V lH414a Va4HCTl4 iCl-a ftl VUM3Z4 R7 470a R6 m CI fl3 470K R12 47K ^ C2 R10 4;oK R9 47K R13 470K V< LM324 CI4 -MA- RS 56K Fia 3— TELEPHONE-LINE INTERFACE presents a higlr-impedance interface to avotd line loading. Note the use of separate analog and digital grounds. fTQ S03T1 ( FROM -9VDC - j ^uoto ^ 07 ^ tli 4148j |-|^ S3_ ~p — ^^ spKfli R20 ZH2Z22 ^/Q^ | LED3 FULL WATCH POG Q4 A 10K >r-*i-"Wr STAT ^ >-^ err LEP4 ON Q1 Rie EN2222 , ^ 10K ^ ^ R19 IOmF 16V . DIGITAL GROUND : AfiALOG GROUHD RG. 4— MISCELLANEOUS CIRCUITS ; (a) shows the reset circuit; (b), (c>, and (D) show the status LED drivers; (e) Shows the speaker driver; (f) shows the RS-232 interface; (g) and (h) show the DTMF interfaces. Use only one of (g) or (h), depending on the availability of DTMF decoder IC s. I Br 3 :3 57 TABLE 2— DTMFTONES High Group Column 0 Column 1 Column 2 Low Group 1209 Hz 1336 Hz 1477 Hz Row 0. 697 Hz 1 2 3 Row 1 , 770 Hz 4 5 6 Row 2, 852 Hz 7 8 9 Row 3, 941 Hz * 0 # ^TcT i-Cl5 _Lci6 Xci7 _LciS X C19 Jlc21 ^_ ^.iMl^ J.ll^F -J.lpf ^JnF Y'^^^^ I'-^HI^ ^ ,C31 ■ft31 ^ 09 i^1H4004 tr 16V -4i |i- DIO 1N4004 ■'I IC1? LM2540T 3 5.QVDC mm &-9VAC 300niA ' 1 i Hyr |br2 ' V J50V 1A IK lOfiF 16V 4JVDC OS ' 4.7V 1N4732A — r 1 PWROII J-' NOTES: i ^ POWER SUPPLY GROUND ^ ^ DIGITAL GROUND ^ = ANALOG GROUND •SEE TEXT FIG. 5— POWER SUPPLY. Note that the digita I and analog g rounds come together here. Also note that R31 should be deleled If nonrechargeable batteries are used- and ring terminals. The high impedance (200K) nature of our design ensures that Digi-Call does not load the phone line. Note: The high -impedance nature of the circuit requires that Digi'Cali be isoMed from grounded equipment during normal operation. Onlyconnect the PC^s serial port cable during data doivnioads; remove the ca- ble immediately when done. Further data recording will not occur with the PC connected! Battery-powered portables are exempt from this limitation. Surge absorber MOVl pro* vides protection against light- ning strikes. Bridge rectifier BRl provides polarity protec- tion; BRl also rectifies the AC ringer voltage. Op-amp ICl-a functions as a voltage com- parator with a threshold of - 2- volts DC. which Is provided by the series connection of diodes D1-D4. The input voltage at ICl-a is the rectified phone line voltage divided down through R1/R2 and R4, which together divide the input by a lector of 10. With the phone fine on- hook, the input voltage at pin 3 of i 01 -a is -4.8-voltsDC, which when compared to tlie -2-voll reference at pin 2 of ICl-a, driv- es the pin- 1 output to about - 9- volts DC. Diode D5 blocks Ihls negative voltage, which would harm ICl-f: that input is nor- mally pulled low by R5. Tiie out- put of ICl-f, DET, drives the interrupt 0 (into) input of the microprocesson as well as bit 7 of input port L The interrupt feature helps the micro- processor determine the follow- ing slates: off- or on-hook, phone- ringing, pulse dialing. All states except on-hook (i.e. » not in use. nol dialing, no in* coming ring) force the input voltage at pin 3 of ICl-a to about -1-voll DC. which drives the output of ICl-a to about -f 5- voUs DC. which through D5 and !Cl-f drives dbt low. Note that both dialing pulses and ringer voltages will cause digital pulses to appear at the output of ICl-f. The primary source of dialed digits is through the DTMF de- coder. IC2. Although Digi-Call can recognize pulse-dialed dig- its, tone dialing is faster, and is now the standard dialing prac- tice in most areas. Also, if you expect to use tlie Account Code feature of Digi-CalL you must have tone-dialing capability The DTMF encoding stan- dard defines 16 dual -tone com- binations. but standard phones generate only 12 of them. Those 12 tones arise from a 3-b3^-4 ma- trix, as shown in Table 2. Seven frequencies are involved in standard DTMF generation; they arc separated into two groups. The row inlbrmation is called the low group: it has fre- quencies 697--941 Hz. The col- umn information is called the high group; it has frequencies 1209-1477 Hz. For example, if you press the digit "3." the 697 Hz tone and 1477 Hz tone are combined. (Note: In 16-digit DTMF. there is an eighth totie, 1633 Hz. in a third column.) Op-amp ICl-c functions as a unity-gain differential amplifier to bLiffer telephone audio. Ca- pacitors CI and C2 AC -couple the audio from the phone line; the pin-8 output of ICi-c (aij[>[o) drives the DTMF decoder (IC2, shown in Figure 4) directly (The clreuit allows for two different DTMF decoders, a 75T204, shown In Fig, 4-g. and a 75T202, shown in Fig. 4-h. The PC board allows use of cither) The DTMF decoder incorpo- rates switched-capaci tor filter- ing to separate the low- and continued on page 88 TALKING DEVICES SP:EM TO BE AIX around us today. Virtually every- where we go we're being spoken to by vending machines, arcade games, toys, cars, and even computer-spoken junk phone calls! There seems to be no limit to applications for devices that mimic the human voice, but the quality of the voice emanating from most talking devices has several serious flaws, its usu- ally monotone, lacking the nat- ural inflection of real speech, and has less than adequate enunciation. In other words, most machine speech sounds *Yobotlc." Worse yet is the ne- cessity of programming a ROM (Read Only Memory) in order to change the message. It*s ob- vious that the standard solu- tions are less than ideal. The ISD 1016 Single Chip Voice Messaging System (Infor- mation Storage Devices* Inc.. Austin. TX] eliminates all those drawbacks while at the same time Introducing several fea- tures and functions which greatly enhance Its versatility and simplify system design. Features As the Indus try s first non -vol- atile analog storage chip, the ISD 1016 can record and play back up to 16 seconds of analog, or "audio** information. All ana- log signal condUioning circuits. ampHfication, and digital con- trol circuils arc contained in the single 28-pin package. There- fore, a complete voice record/ playback system can be imple- mented by simply connecting an external microphone and speaker, and a few capacitors, resistors, and switches to the analog storage chip. Several configuration options are available including multiple message, continuous repeat, and fast fonvard. These options are in addition to. but mutually exclusive of. the message ad- dressing mode, which allows the user to directly address any segment of the analog storage array By offering capabilities such as direct analog input, analog storage, and analog out- put, the ISD 1016 provides a high-grade voice record and playback system. SINGLE-CHIP MESSAGING SYSTEM Our one-chip voice messaging system makes it easy to add audio-storage capability to your next project! p a. m 59 AMAIN INTERNAL CLOCK TIMING FILTER a SAMPLING CLOCK AGC ANALOG TRANSCEIVERS FILTER ANALOG REFERENCE !1.5V ANALOG STORAGE ARRAY^"^ AOORESS BUFFERS r- CONTROL SP+ SP- llllllii o i i_ i 6_ o AO A1 A2 A3 A4 A5 A6 A7 TEST PD P/R ^ EOM AUX IN FIG. 1— FUNCTIONAL BLOCK DIAGRAM OF THE ISD 1016. The microphone signal is capacittvely coupled to the input preamp, and the gain of the preamp is dynamtcatly adjusted by the AGC circuit. Novel approach Key lo the ISD 1016 is the unique method of stoniig the analog signaL Conventional cir- cuits first sample the incoming analog signal and send it to an A/D converter that provides a digital output, typically eight bits wide, which is proportional to the amplitude of the incom- ing signal. Therefore, this method requires at least eight bits of storage per sample. Play- back ol' the data requires that the eight bits of digital data be sent to a D/A converter to re- produce the original analog sig- nal. The ISD 1016 eliminates the A/D and D/A conversions by using CMOS EEPROM (Elec- trically Eraseable Programma- ble Read Only Memory) tech- noiogy and storing the sampled data as an analog level in the PARTS LIST All resistors are y4-watt, 10%, un- less otherwise noted. R1— 2000 ohms R2— 10.000 ohms R3— 470,000 ohms R4— 1000 ohms x 9, 10-pin SIP resistor Capacitors CI, C4— 22 iJt.R 16 volts, tantalum C2, C6— 0.1 ^JlR ceramic C3-^.7 piR 16 volts tantalum C5-— 0>22 jiR poEystyrene C7— 1 ^F, 16 volts, tantalum Semiconductors IC1— ISD 1016 Voice Messaging System Other components S1-S3— SPDT miniature slide switch S4— 8 position DIP switch Ml CI— miniature eleclret micro- phone Miscellaneous: 28-pin fC socket, 16-ohm speaker, power source of at least 5 volts, wire, solder, etc. Note: The following items are available from R. Tenney, 33 Eastmeadow Way, Manchester, N.H. 03109: • ISD 1016 IC— $35.00 • Etched and drilled PC board— $9.75 • A kit of all parts except speaker-*$55.0D. Please add $2.50 postage and handling. EEPROM storage array. This method requires only one cell per sample and has the added advantage of being nonvolatile. The signal can be stored for ten or more years without power. How it works Figure 1 shows the functional block diagram of the iSD 1016. The microphone signal is ca- pacitively coupled to the input preamp. The gain of the preamp is dynamically adjusted by the AGC (Automatic Gain Control) circuit, which reduces the gain of the preamp for large input signal ievcis, and increases it for lower-level signals, thereby ex- panding the range of input sig- nal levels that can be accommo- dated without distortion. The output of the preamp is then coupled to an additional amplifier stage through an ex- ternal capacitor. This stage has two main functions. One is to provide an input to the AGC cir- cuitry^ so it can adjust tlie gain of the preamp according to the s t re ngt h of t h e i nco m i ng signal. The second role of this stage is to drive the filter network which will remove noise and other un- wanted signals outside of its passband* The gain-adjusted and filtered signal is then fed to the analog transceivers. In the record mode, these transceivers lake their input from the input filter and send the signal to the ana- log storage array. In playback mode they take their input from the analog slorage array and send it to the output filter net- work. Timing circuitry internal to the ISD 1016 synchronizes the operation of the analog storage array and the analog trans- ceivers, and also generates a sampling clock. The analog au- dio input signal is sampled by that clock at an 8-kHz rate, which is adequate for an audio passband of 3.4 kHz (about the same as a telephone), and is stored in the analog storage ar- ray as a voltage level. During playback, the storage array is sampled and sent to the output filter via the analog trans- ceivers. This n lie red signal is then sent to one input of an analog multiplexer, which will select one of its two inputs to drive the power amp. In play- back mode, the stored message will be selected, amplified, and sent to the speaker. When not in record mode, and not playing FIG. 2— SCHEMATIC DIAGRAM of the complete voice recording and playback system capable of storing up to 16 seconds of telepti one-grade audio. back a message, the multiplexer will select the auxiliary input as its source, thus allowing us to take advantage of the output amplifier when the ISD 1016 is otherwise idle. Circuit details Figure 2 shows the schematic diagram of a complete voice re- cording and playback system that is capable of storing up to 16 seconds of telephone-grade audio. Before we go over the schematic, lets go over the pin functions of the ISD 1016 to make it easier to understand the overall operation of the cir- cuit. • Microphone Input (mjc), pin 17 — An external microphone is coupled to this input through a series capacitor. The value of the capacitor and the lOK inter- nal resistance of the input de- termines the low-frequenev cut- off for the ISD 1016. A good- quality omni -directional elec- tret microphone is recom- mended. Its impedance should be about IK, sensitivity 64 dB, frequency response 50 Hz to 8 kHz, and S/N ratio greater than 40 dB. Refer to the parts list for sources. • Analog Out (ana out), pin 21 — The amplified analog input signal appears on the analog output pin. The gain of the pre- amp is determined by the volt- age level at the AGC pin. Maximum gain is about 24 dB for low-level signals. • Analog Input (ana [n), pin 20— This pin has two roles. Tlie analog output (pin 21) of the preamp can be coupled via an external capacitor to this analog input pin. The value of the ca- pacitor and the 2.7K input re- sistance of this input pin can provide additional cutoff at the low-frequency end of the pass- band. Alternatively* this pin can be used to input analog signals other than the microphone sig- nal. • Automatic Gain Control (AGcl, pin 19 — As described in the sec- tion on the block diagram, the AGC circuit will dynamically ad- just the gain of the preamp. Peak output voltages of the pre* amp will be delected and charge an external capacitor. The time it takes for the capacitor to charge lo a level that will start to reduce the gain of I he preamp (about L8V) is known as the' at- tack time." and is determined by the value of the capacitor and the 5K internal resistance of the AGC input. The "release time" of the AGC is determined by this capacitor In parallel with an ex- ternal rcsislon • Speaker Outputs (sr+K pin 14 and (si* 1, pin 15— The ISO 1016 can directly drive speakers with impedances as low as 16 ohms. The maximum output power of 50 mW is achieved when the speaker is connected between these two pins. In that configuration no coupling ca- pacitor is required. The device can be used in a single-ended configuration: however, an AC coupling capacitor must be used and the output power will be reduced lo about 12 mW. While recording, the speaker outputs are disabled. An 8-ohm speaker can be used, but the volume will be louder and some audio distortion can result, • Power Down (pd), pin 24 — This pin serves two purposes in the operation of the chip. First, it provides a low-power mode when the ISD 1016 is at idle (not recording or playing back) and the pin is Iiigh. The second function of this pin is to provide a means to reset the address counter. Wlicnever the ISD 1 01 6 reaches overflow (after 16 sec- onds total record or playback time) the address counter is at its maximum recording count (9Fh) and an bom (end of mes- sage] pulse will be generated. Activating ce (chip enable) will not restart the device until vd was cycled high and low, NOTE: Wlien recording multiple mes- sages, the user should termi- nate each message by disabling vE while keeping rn low. That will prevent the address coun- ters from getting reset to zero at the start of the subsequent message, thereby causing the previous message to be over- written- CE h P/R ^^i^ \ ^ I DOfjT car e" PD D0N7 CAHE \ |-^T„ot, —^j hm< -j/ pp^^ ^^f^^ A0-A7 D0N7CARE) j C '• ) ! ( j DQNT CAR E MIC % — ^ I SP- FfG. 3— RECORD TIMING DIAGRAM, See TabJe 1 for a description of the parameters. \ * — TscT • - — ^ , /{ j \ I OOm CAR E ' PO DOfJ T CARE 1^ - Wd --H Dojj^ ^ARE A0-A7 DOn'T CARE) ^! ^^ j ) } ( DQMT CARE ' ~ SP+ fi^'I'scJ— H EDM ^ ' W H-^T^H^-H FIG. 4— PLAYBACK TIMING DIAGRAM. When operating the device under micro- processor control or other high-speed device, these parameters must be considered. • Chip Enable (ce). pin 23— When taken low, this pin en- ables all playback and record op- erations. The address and play/ record inputs that meet the set- up time {300 ns) are latched on this falling edge. When this pin is taken high, the iSD 1016 is deselected and the Etuxiliary in- put is selected as the input to the output power amp. • Play /Record (p/r}, pin 27— The state of this input is latched into the ISD 1016 on the falling edge of CE (along with the ad- dress inputs (ao-az). a logic high selects playback mode and a logic low selects a record oper- ation. The message to be played will start at the address latched when cl went low. The messaf^e will continue until an bom (end of message) is encountered on pin 25. The eom bit is automat- ically inserted during a record operation when the storage area is full or when the record opera- tion is terminated by pd going low or CE going high-. If multiple messages have been recorded, CE should be pulsed low for the device to playback a single mes- sage. If CE is held low (active), all the stored messages will be played back in sequence, • Address Inputs (ao-a7), pins 1—6, 9, 10 — i\vo functions are performed by the address in- puts: mode and option selec- tion > and message address. The ISD 1016 has two modes of oper- ation. Address Mode and Con- figuration Mode. Address bits 6 and 7 determine which mode will be selected. If either bit 6 or bit 7 is low, Address Mode will be selected. In that mode the ad- dress pins specify the starting address of the operation to be performed. If both address 6 and 7 are high, the configura- tion niode is selected, T^ble 3 lists the configuration mode op* tions. Of the options listed, con- tinuous repeat and multiple message recording can be of the most use to the experimenter Further details of their use can be found in the section on "Modes of Operation." • End Of Message (eom), pin 25 — At the end of each recorded message, an eom marker is au- tomatically inserted in a non- volatile register The eom output will go low at the end of each message and at message over- flow. The width of the negative pulse is 12,5 ms minimum. An- other function of eom is as a low-power indicator. If power to the chip should drop below 3,5V, EOM will be forced low and the JSD 1016 placed in playback mode. This feature helps pre- vent recording while in an unre- liable power condition, • Auxiliaiy Input (aux in), pin 11 — ^As explained earlier, aux in is selected as the input to the ou tput power amplifier when ci- ther EOM is true or ce is not true, thus allowing us to take advantage of the amplifier for other uses when the ISD 1016 is oLhenvtse Inactive. • 5-volt Analog and Digital Power Inputs (V(^^tv\), pin 16 and (Veen)- P^n 28— The ISD 1016 voice messaging system chip in- corporates both digital and ana- log circuitry. The digital circuit- ry generates considerable noise from rapid switching of gates within the device, as does any other digital device. The noise is easily detected by the analog cir- cuit ly and can, therefore, be re- corded as noise in the analog signal. For that reason, separate power and ground buses are provided for the analog and dig- ital portions of the device. In tlial manner, currents flowing in the digital portions of the de- vice cannot cause significant voltage iluctuations tn the ana- log power buses. The two power pins should be connected to- gether as close as possible to the power source. That is the only location where the two power busses should be connected to- gether. If another direct connec- tion between V^ca "^con were to be made at any other point, a "loop" would be formed and sliglit voltage differences between the two points would cause unwanted currents to flow in this loop, providing an- other source of noise. • Analog and Digital Ground Connections (Vs^a^* pi^ ^3 and {Vssd). pin 12— NOTE: The ground connections for the ISD 1016 do not conform to a stan- TABLE 1— TIMING & VOLTAGE PARAMETERS Symbol Parameter Value FS Sampling Fr6C|. 8 kHz BW Bandwidth 3400 Hz Ivo P OUT Speaker Output Power 50 rnW max. IjM 1 Mic Input Voltage 20 mV max. p-p IN2 Ana InDut Voltaae Aux Input Voltago 1 .25 V max. p*p SET Control/ Address Set-up 300 ns min. Co ntrof /Address Hold 0 ns max. CE Record Time 100 ns min. ''"pud Power Up Delay 25 ms min. Power Down Hold 0 ns min. Record Time 16 s max. Playback Time 16 s max. '''eom EOM Pulse Width 12.5 ms typ. |-^^ 3^/4 INCHES ^ FOIL PATTER M for the voice messaging system, dard 28- pin DIR V^sa ^sso are the return paths for the ana- log and digital sections of the device, respectively. Follow pre- cautions similar to those de- scribed for the power inputs. Pins 12 and 13 should be tied together at the package, and power should be decoupled using 0. I^jlF capacitors between V^j^ and V^^. as close as possi- ble to the package, for both ana- log and digital power. • Test Input, pin 26 (test)— This pin is used during the manufacturing operation prior to product shipment. For prop- er device operation this pin must be tied low. Now that we have a better un- derstanding of how the ISD 1016 works, lets go over the schematic (Fig, 2). Resistors Rl and R2 supply the microphone bias for the el ec tret microphone (MICl) recommended in the parts list. Capacitor C4 pro- vides microphone decoupling and C5 provides input coupling and DC blocking for the micro- phone wh ile also acting as a sin- gle-poie, low-frequency cutoff filter Capacitor C7 provides AC coupling between the preamp output and the input ampiifien and also provides additional low-frf:quency cutoff. Resistor R3 and capacitor C3 provide the AGC attack/release time constants. For strong in- put signals, the AGC circuit in- ternal to the ISD 1016 starts charging C3. If the signal re- mains strong long enough for C3 to reach the AGC threshold level (about L8V), the gain of the preamp is reduced to pre- vent it from being overdriven. If the input signal leve! decreases, C3 starts to discharge through R3. thus increasing the gain of the preamp for ^ow-level signals. Capacitor C 1 provides V^.^. de- coupling, C2 is the V^.^.^ high- frequency decoupling capacrton and C6 provides the same func- tion for Vcxzo- CI should be lo- cated as close to the supply as possible, and C2 should be as close to ICI as possible. Switch- es SL S2. and S3 provide the control functions for rLAvimcK/ RKCOHD. POWERDOWN, and CHIP ENABLE inputs respectively Resistor R4 is a SIP (Single- Inline-Package) containfng nine resistors, one of which is not used. Those pull-up re- sistors are used so we can im- plement the address switches with an inexpensive eight-posi- tion DIP switch (S4) instead of eight individual switches. The output amplifier of the ISO 1016 is designed to drive a 16-ohm speaker: a standard 8- ohm speaker can be used, but youHl end up with slightly loud- er volume, slightly greater power dissipation, and some distortion. In general, the better the quality of the speaker, the better the sound quality. Timing diagrams Figures 3 and 4 show the tim- ing diagrams for the record and playback modes respectively The parameters referenced are shown in Table 1. When operat- ing the device manually, param- eters such as setup and hold times are met by simply follow- ing the recommended pro- cedures outlined later in this article. When operating the de- vice under microprocessor con- trol or other high-speed device, these parameters must be con- sidered when controlling the chip. For example, tosetupfora record operation the address lines should be set by one in- struction and the ce line set by a subsequent instruction to en- sure the 300-ns controVaddress setup time (T^irx) is met. Constniction A complete kit of parts, in- cluding an etched and drilled PC board. Is available from the source In the par Is lisl. A foil pattern is provided here if you would like to make your own board. None of the component values are critleaL but be sure to leave pins 7. 8, IS. and 22 un- connected* no matter what you do. If you Ye maki ng your own layout, some simple guidelines should be followed for best re- sults. Note that V^^^^^ and V^cd should be connected at one point only, right where power enters the board. Likewise, ^ssA ^ssn should be con- nected together right at pins 12 and 13 of ICL That isolates the analog signal and ground paths from the digital paths* thus re- ducing noise. Also, the analog components should be phys- ically separated from the digital r -lr^.rh + i ! +M SPKR FIG. 5— PARTS PLACEMENT DIAGRAM. Mounting tho DIP switch (84) in a socket will give you convenient access to the address lines If you wish to control the circuit with a microcontroller Be sure to position switch #1 of tha DJP switch at the top. FIG. fi— THE COMP LETED PROTOTYPE. The 9- volt battery clip attaches to a 4*AA cell holder that has a matching con- nector; the prototype voice messaging system* therefore, is powered from a total of 6 volts. TABLE 2— OPTIONS Function Playbacif chip enable level activated Message start pointer resel only play record changed Continuous repeat of message During playback eom pulses low at overflow only Address Use Bit 5 Provjde switch debounce EOM mariners deleted by next message Fast fon^rard (speaker output is disabled) components for those very same reasons. Figure 5 shows the parts placement diagram. The ISD 1016 tlCl ) should be mounted In a 28-pin socket, whicli can be installed now, but leave the (C out for the moment . DIP switch S4 should also be mounted in a socket to give convenient access to the address lines should you wish to control the circuit with a microcontroller. Whether or not you use a socket, the DIP switch should be mounted with switch #1 at the top. Next mount SIP resistor R4 (with pin 1— the dot— at the lop), followed by the various ca- pacitors, discrete resistors, and the microphone. Be certain lo ot>serve polarity when installing Ci. C3, C4. C7. and the micro- phone. Next mount switches S1-S3 and the leads for the speaker and the power source. (The prototype uses a standard 9-volt battery clip and a 4-AA cell holder that snaps onto the 9- volt clip.) Figure 6 shows the completed protot>pe. After all components have been mounted, check for any shorts or solder bridges^ and verify proper orientation of all components. After these checks have been made, install ICl in its socket verifying proper ori- entation, and connect a speaker to the speaker terminals. Operatloa Before connecting power lo the circuit, set all switches to Recording multiple messages Continuous repeal at eom encounter Concatenate chips for longer messages t Assures that EOM markers are cleaned up when recording over message 0 Selecting nrtessages when address is unknown the following positions: SL Play/Kecord— Play 52, Powerdown/Up — Douti 53, Chip Enable— Disable 54, AO-Ay— Closed Apply power and check for the proper voltages at ICl before continuing. Td record a message: • Close all switches on S4. • Set SI to "Record. ' • Set S2 to "Power up." • Set S3 to "Enable/* That starts the ''Record*' time and you can record up to 16 sec- onds of speech by speaking into the microphone, as with a tape recorder. Speak with your mouth close lo the microphone in normal voice. Wlien you are finished recording your mes- sage you should: • Set S3 to "disable/* • Set S2 to "Powerdown." • Set SI to "Play/* To piay back a message: • Set SI to "Piay/' • Set S2 to "Power up/* • Toggle S3 to the *Enabie*^ po- sition and back to the "Disable" position. Your pre-recorded message wili now piay back and stop at the end. When the message is com* plete, set S2 to the "Power down" position. Addressing mode The ISD 1016 has tw^o mutu- ally exclusive modes of opera- tion: the "Addressing Mode" and the "Configuration Mode/* The addressing mode is selected conXimxedi on page 92 ITS EASIBR THAN YOU TI TINK TO DE- sign LED display drivers with National Semiconductor b LM391X and LIV12917 series IC's, In this article, well show you how to use those ICs to build moving-dot and bar graph voltmeters as well as frequency- to-voltage converters. We'll also give you an introduction to bin- ary coded decimal (BCD) to 7- segment decoder/driver circuits that are commonly used in elec- tronics design. LIVf391X-series basics National Semiconductors LM391X dot/bar display drivers are versatile 18-pin DIP IC s that can be used to drive up to 10 LED s in either dot or bar mode. The three members of the LM391X display driver series are the LM3914, LM3915, and LM3916. All three versions use the same basic internal circuit- ry^, as shown in Pig. 1, but have different output scaling modes, as shown in T^ble 1. The LM3914 is a linearly- scaled device that's intended for use in LED voltmeters, with the number of lit LEDs being di- rectly proportional to the input voltage (pin 5). The LM3915 is a logarithmically'Scaled device that s intended for use in power meters, and spans a range of 0-30 dB in ten 3'dB steps. Fi- nally, the LM3916 is a semi -log- arithm] cally-scalcd device that's intended for use in volume-unit (VU) meters. Figure 1 shows an LM3914 used in a simple 10- LED volt- meter, which ranges from 0 to 1.25 volts DC. The LM3914 has 10 interna] comparators, each with its non-inverting terminal connected to a specific tap on a floating, precision. 10-stage, in- ternal resistive voltage-divider. The inv^erting lermirials on all ten of the comparators are fed by a unity-gain buffer on pin 5. Each comparator is externally accessible, and can sink up to 30 milliamps. The sink cur- rents are internally limited, and are externally pre-set via RL The LM3914 also has a float- ing 1.25-volt DC reference be- tween pins 7 and 8, externally connected to the 10 -stage inter- nal voltage divider on pins 4 and WORKING V/ITH DISPLAY DRIVERS Let^s take an in-depth look at LED display drivers. RAY MARSTON C0MP1 1 imnn [immm] G,63K(3915>< 1K13914) 1 (FiW 11) 1K(3914) > 3,31K{39^5)5 1K[39t4) L 1K(3914) 1.66Kp915) ^ 1K(3914) 1.17K(3&15) : 1K{3914| 93(}ti(3915j ai9Q(3916l iK[39l4) L 92311(3916) 1K{3914) 41DU{3915} : 1> 1K(39t4) 7680(3816} I com .C0MP3 H 17 j -1 to T 1 I -il5 I I COMPS ^ COMPS I . J RG. 1— I NTERN AL CIRCUrT OF THE LM3914, with connections for making a 10-LED, 0 to 1.25 volts DCt linear meter using either dot or bar mode. 6. Pins 4 and 8 are grounded^ so that the bottom of the lO-stage internal voltage divider is at grounds and the top is at 1.25 volts DC. The LM3914 also has an internal logic network that can be used to select either mov- ing-dot or bar-graph mode. If the LM3914 is set for bar mode, the 1.25-volt DC refer- ence is connected across the 10- stage internal voltage divider Because of the linear scaling of that divider, each succeeding inverting comparator input has an additional 0J25 volts DC ap- plied to it. \Vlien there is no signal on the input, pin 5 is at ground, all 10 internal comparators are dis- abled, and LEDs l-^-lO are off. With a slowly rising signal on the input, the voltage increases to L25 volts DC. and an LED lights for each 125-millivoU in- crement, until LEDs 1-10 are on. In other words, at the 125- millivolt DC threshold of the first comparator. LEDl lights, at 250 millivolts DC. LED2 also lights, and so on. When used in dot mode, only one LED at a time lights. Some finer details In Fig. L Rl is connected be- tween pins 6 and 4. fixing the current through each LED. The current through each LED is ten times that drawn from the 1.25-volt DC reference. The 1.25-volt DC reference can source up to 3 milliamps, so the maximum current through each LED is 30 milliamps. set by Rl, but the LED current doesn*t normally get that high. The nominal value of 1.25 volts DC can also be varied be- tween 1.20 and 1.32 vol Is DC, or its value can be externally pro- grammed to produce up to 12 volts DC. If Rl equals 1.2K, then Rl in parallel with the full lOK value of the uiternal voltage di- vider is equivalent to 1.07K. The current drawn from the 1.25- volt DC source is 1,25 V/1.07K = 1.2 mA, so that each LED nominally draws 12 milliamps when it s lit. Since tlie maximum individ- ual current through each LED is 30 milliamps, then the LM3914 draws up to 300 milli- TABLE 1— COMPARISON OF TYPICAL INPUT THRESHOLDS FOR THE LM391X iC FAMILY LED LMa915 LM3916 V V dB V dB vu 1 l.UUU 0.447 - 27 0.708 -23 ^20 o <;.uuu 0.631 -24 2.239 - 13 -10 O o.byi - 21 3.162 — 10 - 7 A *t.UUu - 10 j.yoi — O - 5 1.778 -16 5.012 - 6 - 3 6 6.000 2.512 -12 6.310 - 4 - 1 7 7.000 3.548 - 9 7,079 - 3 0 8 8.000 5.012 - 6 7.943 - 2 + 1 9 9.000 7.079 - 3 8.913 - 1 + 2 10 10.000 10.00 0 10.000 0 + 3 C0MP2 C0MP3 C0MP4 C0MP5 C0MP6 C0MP7 C0MP8 C0MP9 COMP10 LM3914 coMPt nm IfJ m HI 6 m LO MODE 8 R2 1.2K Rx i FIG. 2— A MOVING-DOT VOLTMETER with a range of 1.25 volts to 1 kilovoJI DC. LEDl LE02 LED3j LED4 LEDSf LEOB LED7 LE08 LEDST LEDIO} 1 IB |l7 1G 115 U 13 12 hi ilO ! C0MP2 C0MP3 C0MP4 C0MP5 C0MP6 C0MP7 COMPB C0MP9 COMPIO LM3914 IN R| i CI " lOjiF BEF REF HI LO MODE 0-10V 1 1.2K {ZEWER VALUE 01 L SETS MAXIMUM 1N524a* INDICATED VOLTAGE) 10V ^ FIG, 3— A VOLTMETER RANGING from 0 to 10 volts DC using an external reference. amps total In bar mode with LEDk 1-10 on. The maximum power rating of an LM3914 is only 660 milliwatts, which can easily be exceeded in bar mode ii* you re not careful. The LM391X series runs on a supply of 3-25 volts DC, and the LEDs can use the same voltage supply^ or they can use an independent suppl}^ for minimal iC heat dissipation. The internal voltage divider is floating, with both ends exter- nally available for maximum k+5-m lEDI l€D2 LED3 LED't LED5| IED6| LEOtT LED8 __LED10 18 LED3 17 LED't 16 t5i 14i 12 LE09 11 L£D10 10 C0MP2 C0MP3 C0MP4 C0MP5 C0MP6 C0MP7 C0MP8 C0MP9 C0MP10 UT3914 C0MP1 Gr^O IN HI REF LO MODE ^ CI 1 T 0-10V ? 8 R1 1.2K SfTS MAXIMUM INOICATEOVOLTASE R2 10K FIG. 4— AN ALTERNATE VARIABLE-RANGE voltmeter that can allow a varfatfon in the maximum value of its range from +1.25 to 10 volts DC. [>3 1 LED4T j F05 1 LEOeT LEDtT LED8 T LED9 \ LEOIOT LE01: LE02i LED3| LED4 ■ LEDS | LED6 5 LEDTI LED8 1 LED9^ lia 17 i16 115 jl3 [12 !10 C0MP2 G0MP3 C0MP4 C0MP5 CQMP6 C0MP7 coMPe C0MP9 COMPIG REF REF C0MP1 Ru> IN Rill H! LO MODE =IG. 5— AN EXPANDED-SCALE MOVI NG-DOT voltmeter that ranges from 10 to 1 5 volts RED LED'S y^ GREEfJ LEO'S RED LEO'S oooooooooo + 10.5V +nv 4l1.-?V +t2V +12.5\/ +13V +13 5V -fUV +t4.5V +15V * 12V (NOMlfJALlTO CAR BATTERY VlAIGrjtlfON SWITCH) C0MP2 C0MP3 C0MP4 COMPG COMPG C0MP7 C0MP8 C0MP9 C0MP10 LIV13914 REF REF C0MP1 GND HI LO MODE 4r CI I lOnF I m 4JK (SETS UPPER LtMtl . or 15V ON measurement: FtANGH) R2 i t.2K? R3 5K R4 5K X (SETS LOWER LIMIT OF10.5VON : MEASUREMENT RANGE) FIG. 6— AN EXPANDED-SCALE DOT-GRAPH voltmeter for use with a car battery. v^ersatility, and it can be powered by either the internal reference or an external source. If pin 6 is connected to 10 volts DC , then the LM39 1 4 becomes a voltmeter ranging from 0 to -h 10-volts DC if pin 4 is grounded, or a restricted-range DC voltmeter ranging from 5 to 10 volts DC if pin 4 is connected to 5 volts DC. The only constraint is that pin 4 cannot go more than 2 volts below V^^-c-. The input is fully protected af^ainst over- loads up to ±35 volts DC. As wc mentioned carlien the major difference between the three members of the LM391X family is in the weighting of the ten-stage internal voltage divid- ers. In "the LM3914, the values are equal, producing a ten-step linear displaj^, hi the LM3915, the values are logarithmically- weighted, producing a log dis- play spanning 30 dB in ten 3-dB steps. The values are semi-log- arithmically weighted in the LIVI3916, producing a volume Luiit (VU] meter display. Lets now examine some LM391X ap- plications, focusing on the LM3914. Moving-dot voltmeters Figures 2-6 show the LM3914 used in various 10-LED moving- dot voltmeters. In all of them, pin 9 is connected to pin 11, and a 10 p.F capacitor is connected betw^ecn pins 2 and 3 for sta- bility: Figure 2 shows a variable- range moving-dot voltmeter that can cDver a range of 1.25 volts to 1 kilovolt DC. The low ends of the internal reference and the 10-stagc Internal volt- age divider are grounded, while the top ends are joined. The voltmeter has a basic lull-scale sensitivity of 1.25 volts DC, with \^ar table ranging provided by voltage divider Rx-RL When Rx equals 0 ohms, tlie full-scale value is 1.25 volts DC, and when Rx equals 90K. the full -scale val- ue is 12.5 vol is DC. Also, R2 is connected across the internal reference and sets the current through each LED at 10 milli- amps* as before. Figure 3 shows a fixed- range moving-dot voltmeter that can LED1 1 18 M7 16 h5 14 \2 HI !10 C0MP2 C0MP3 C0MP4 C0MP5 COMi^O a)lWi aoMP8 C0MP9 COMP10 LM3914 REF COMPI GND ^to IN ^Hl HI LO MODE 4- PI 4- Rt . ^ CI R! 10K 1.2K ' FIG. 7— A BAR-GRAPH VOLTMETER USING a separate supply for LED% 1-10. J ! LED1 D\ LED2; LE03i LED4; LEDsf LED6: LED? LEOsT LED9; LED10I i R2 i R3 i R4 i m i R6 i R8 4 R9 < RTO J 47012 f 470Q ^ 47Gi2 f ? 470Qf^ 470Q 4700 f Aim f 4M^^ il8 17 il6 il5 il4 13 il2 J1 iii}^^^ HI 470U C0MP2 C0MP3 C0MP4 C0MP5 C0MP6 C0MP7 C0MP3 G0MP9 COMPIO COMPI GfJO LIVia914 ^io m REF HI REF LO MODE IOmF I ! R12 1.2K V^s=r2V|URj^/mi) FIG, 8— A BAR-GRAPH VOLTMETER USING a coinmon supply for both IC1 and LED's 1-10. + 24V(REGUUfrED) LED1 LED2 LED3 LED4 LE05 LE06 W LE07 LEDa LED9 LED10 18 jl7 16 15 14 13 12 11 10 C0MP2 C0MP3 C0MP4 C0MP5 C0MP6 C0MP7 C0MP8 C0MP9 COMPI 0 LM3914 COMPI qm Rio m ^1 2 j 3| - CI I lO^F 1 # Rl 100K flEF REF HI LO MODE R2 t.2K " FIG, 9— A BAR-GRAPH USING dot-mode operation and consuming minimal current cover a range oi 0 to 10 volts DC. U uses an external Zener diode reference Dl going to the top of the 10-stage internal voltage di- vider for a 10-voIt DC reference. Also, the supply must be at least 2 voks DC above the Zener refer- ence level, or a value of ^10 V 4 2 V, -12 V Figure 4 shows an allernate voltmeter with its internal refer- ence providing a variable volt- age for a full-scale value ranging from 1.25 to 10 volts DC. The 1.2-milliamp CLirrent Hxed by HI goes to ground via R2. raising the reference value on puis 7 and 8 above zero. If R2 e€|uals 2.4K, then pin 8 will be at 2.50 volts DCt and pin 7 al 3,75 volts DC- Thus, R2 lets ]>in 7 be var- ied from L 25 to 10 vol Is DC. Figure 5 shows an expanded- scale moving-dot vollmeter that can cover a range of 10 to 15 volts DC. Here. R3 sets the cur- rent through each LKD at 12 mill lamps, and enables a refer- ence level of 0 to 1.25- vol is DC to be set on pin 4, the low end of the 10~stage internal voltage di- vider If R3 is set for O.B volts DC on pin 4. then the voltmeter will read in the range of 0,8 to 1,25 volts DC only. By designing volt- age divider F41-R2 for a s pec i lie circuit, the range can lie ani|3ii- tied as desired. Figure 6 shows nn expa tided - scale moving-dot vollmeter lhats intended lor lisc in your car to continually [iieasure llic status of its 12 -volt battery Here, R2-R4 provides a basic range of 2.50 to 3.75 volts DC. but the input is derived from the positive supply via R1-R3, The reading thus corresponds to a pre-set multiple of the basic range vakie. The display uses red and green hEDs, vvitli the green LEDs lighting when the V(.(. range is within 12 to 14 volts DC. The red LEDs light with 10 to 15 volts DC. To calibrate the volt mete n set V^^ to 15 volts DC» and adjust R3 so that LEDlOjust turns on. Next, reduce V^.^^. to 10 volts DC. then adjust R4 so that LEDl just turns on, and then reeheck both R3 and R4. Finally place the voltmeter between grotnid and the 12-volt-DC lead on the ignition switch. Bar-graph voltmeters The moving-dot voltmeter ver- sions of Figs. 2—6 can be made into bar-graph voltmeters by connecting pin 9 to pin 3 in- stead of to pin IL However, as we mentioned earlier, don't ex- ceed the IC power rating in bar mode with excessive output voltages when LEDs 1—10 are on. Figure 7 is a bar-graph volt- meter thai uses a separate sup- ply for its ten LED's. Most LED's drop about 2 volts when on. so one way around that problem is to use a separate 3 to 5-volt DC source for them. as shown in Fig, 7, Figure 8 is another variation of the bar- graph voltmeter using the same supply for the LM3914 and the ten LEDs, If you use the same supply to operate both the IC and the LEDs, then be sure to use a currenl-Umitlng resistor in series with each LED as shown in Fig. 8, so the IC out- put terminals saturate when they are lit. Figure 9 shows another bar- graph display* one that doesn't exhibit excessive power loss. Here, LEDs I-IO are all in se- ries, but each one is connected to an individual IC output, and the IC is in dot mode. Thus, if LED5 was on. Its current would be drawn through LEDs 1^, so LED's 1-5 would also be on, creating a bar-graph display. In that case, the total current through all of the LEDs is that of a single LED, so the total power dissipation is ver>^ low. m 47m + 12-1SV LHJI LEDZ LE03 18 LED4 1I_ LED5 16 CI 02 3li39i R4 4JK R5 22m D1 1N414d — w~ 02 1N414e LQ>6 15 LED7 13 1MB 12 LED10 10 C0MP2 C0MP3 C0MP4 C0MP5 COMPS COMPT C0MP8 C0MP9 COMPIO LM3914 COMPl GWO ri 3l 41 sT" ' lOiiF low ! REF HI LO 6 7 9 ^ ^4 MODE R2 t.2K (MAXIMUM 9 0F1-2VI ^ FIG. 10— A MODIFICATION OF THE VERSION m Fig. 9. using an unregulated 12 lo IB- volt DC supply. ^^^^^^^^^^ tEfJlT LIDS' LiDsT LtOlj LtDSj UDk- LED? ; lie |t7 lis lis \u WUPi QQim COMW a>MP5 COMPS C0MP7 CQMPB COMJ^ CO*ff^O IC1 until PEF em J 1^ 1 m L0 i T \.2K mm 9 LIDH n5 10K \Z ttDl3 LED14; LED IS] |l7 U jl! jw ilL D0i*P3 COMPS ooim cowp? C0MP9 Ct^WPtO REF DDMP1 GHO RtB IN ^ HI LO MODt ca 10^ FIG. 11-A MOVING-DOT 20-LED VOLTM ETER that ranges from 0 to 2.56 volts DC when Rx equals 0 ohms. RG. 12— A B Afl-GRAPH 20-LED VOLTMETER that ranges from 0 to 2.56 volts DC when Rx equals 0 ohms. The supply for the LED's has to be greater than the sum of the total drop with LED's 1-10 on, but wUhin the voltage limits of the !C. Here the V^^^^ is a regu- lated value of 24 volts. Figure 10 shows a modilica- tion of Fig, 9. using an unregu- !att*d ^- ranging between 12 and IB volts. In that case. LEDs 1^10 arc split into two chains, with Ql and 92 switching LEDs 1-5 on when any of LED s 6-10 are active: the maximum total current through the LEDs is twice that of a single LED. The 20-LED voltmeter The circuit in Fig, 1 1 uses two LM3914S in a 204eD moving- dot voltmeter The inputs of ICl and IC2 go in parallel, but ICl reads 0 lo L25 volts DC, while tC2 reads 1.25 to 2,50 volts DC. For the latter range, the low end of the 10-stage internal volt- age divider in IC2 is contiected to the l.25-volt DC reference of ICl. while the top end is con- nected 10 tlie top of the 1.25-voll DC reference of !C2, 1.25 volts DC above that of IC I . The ci reui I is in dot mode, with pin 9 of ICl going to pin 1 of IC2. and pin 9 of 1C2 to pin 1 1 of IC2; note that Rl is in parallel with LED9 of ICL Figure 12 shows a 20-LED bar-graph voltmeter that ranges from 0 to 2.56 volts DC, the connections arc tike those of Fig, I L except that pin 9 is con- nected to pin 3 of each IC, and R1-R20 go in series with LEDs 1-20 to reduce power dissipa- tion. Finally Fig. 13 shows a fre- queney-to-voltage converter cir- cuit, capable of converting the circuits in either Figs. 11 or 12 into a 20-LED tachometer suit- able for use in automobiles. Here, ICl is a National Semicon- ductor LM2917 monolithic fre- queney-tO'Voltagc converter IC connected between the vehicle contact-breaker points (used in older cars) and the input of the voltmeter In Fig. 13. 0.022 \iF is the optitnal value of C2 for a 10,000-RPM range on a 4-cy lin- den 4-stroke engine. For much lower fulLscale speeds, the val- ue of C2 might need to be changed for vehicles that have + 12V i — 1 14 I — r 13 -I 12>-H 11 i~| to ^ — I 9 a I---* TO COMTACT OREMER (CB) POINTS O iM2StJ 10K R2 m CHARGE PUMP 1 NEtSATlVE tCHASSI&l O" — - % 1M5Z4Z i Ct j Igy -022 ! 'T"^ ' ^ '-^ '^••^ S I— -» 1 I— I 2 H 3 f*—t 4 Jh— < 5 6 » 1 7 I---' ^ ] t ] ' i m 1 > R3 ^220K'p m (FOR 1OO0O-aPM,{ 4-ca.4- C3 STROKE EwilME^ T RG. IS— A CONVERSION CIRCUIT FOR A car tachometer, for use with a 20-LED voltmeter^ as shown in Figs. 11 and 12. + 12-20V 20OmW 4Q0mW dOOmW 1.6W 3.2W 6.4W 12.SVV 25.6W 51. 2W 102 4^^ L£02 1 LE03 j LED4 : LED5 \ LED6| LEDtT l£DB^ !t7 E16 15 14 n C0MP2 CDMP3 C0MP4 C0MP5 C0MP6 C0MP7 COMPB C0MP9 COMPtO LM3915 REF REF COMPl ^XQ IN Ml LO MODE - 10|tF SPKR m 10K R4 I 4U 10K 1 m m 1 mi 30K FIG. 14— A SIMPLE AUDIO POWER METER. v'20VU-10VU -7VU -5VU -3VU -1VU OVU -hlVU + LB)1 TlED2 1lED3 TLHM LC05 ILED6 TlH)7 jLEDS LE09 iLEDIO 115 14 113 C0MP2 {X}MP3 C0MP4 G0MP5 CQMP6 C0MP7 C0MF8 aMP9 COMP10 REF REF C0MP1 GMO HI LO MODE -^t- C2 lO^F 01 1H414B (MAXIMUM OF 14Vi Rl R2 1MEG 3aK --^W — 7^ B R3 4 R4 IK ?4,7K + 15V J R5 (SET 5K 10V ON PINT) U1 .1 02 # 1114002 T HQ. ^S—A SIMPLE VOLUM£-UNfT (VU) METER. ft 22V (REGULATED) ^2ovu -lovu -rm 5VU -3VU ^IVU OVU +1VU +2VU +3W m CALIBRATION Ra PRECISION VU METER with low current drain. FIG. 17— THE STANDARD CON FIGUR AXIOM for a 7-segment LED display. six or more cylinders. LM3gi5 and LMSdie circuits The LM3915 logariUirnic and LM3916 semi-Iogarilhrnlc ver- sions basically work I he same way as the LM3914, and can be directly sLibstituted in most of the circuits shown in Fij^s. 2-12. The LM3915 and LM39I6 wilJ give an LED meter reading for an AC signal going to the input, and respond only to positive halves of the signal, with the number ol" LEDs lit being proportional to the in- stantaneous peak value. The IC should be in dot mode, and set COMMON bo oooo 00 6o 6o 6069 aX ^±^± ^± ®X '1 ol^SpX FIG. 19— THE SCHEMATIC OF a com- mon^anodt T^segmenl LED display. COMMON 1 11 ioo 60 09 69(!»Q 60 60 FIG. 20— THE SCHEMATIC OF a com- mon-cathode 7- segment LED display. for 30 milliamps of LED drive. Figure 14 shows an LM39I5* based audio power meter. Pin 9 is left open for dot mode, and Rl equals 390 ohms, for an LED current of 30 milliamps. The range of the audio power meter is 200 mllliwatts-lOO watts, A better approach is to half- wave rectify the signal on the input and Iced in the resulting DC, as shown in the VU-meter circuits of Figs. 15 and 16, Figure 15. a simple volume- unit (VU) meter, uses an LM3915 in bar mode; the signal at the inpLil is rectified by Dl and liltered by R1-R2-CL with D2 compensating for the for- ward drop of Dl. Figure 16, a precision VU meter offering low current drain, uses an LM3916. with the combination oflCl-Dl- D2 acting as a precision half- wave rectifier Also, LEDs 1-10 are in series, and 1C2 is in dot mode, giving a low-power bar-graph display Tb calibrate the audio [X)wer meter, adjust RIO for 10 volts DC on pin 7: R9 controls the level of display brightness. Tlie y-segment LED display Alphanumeric displays are used in electronics, in digital watches, pocket calculators, and in test equipment such as multimeters and frequency counters* The most common SEGMENTS DlSPUff SEOMENTB a c (f 8 t g a b c e 1 g 1 1 1 1 1 0 \~\ 1 1 1 t 1 1 1 0 1 0 0 0 J \ 1 1 1 0 1 1 1 1 0 1 1 : 0 ~i i_ 1 1 1 0 1 1 1 1 r ^ 1 1 0 0 0 0 i 1 1 1 1 1 0 1 a 0 1 t t s 1 Q 0 1 1 1 0 1 Q 1 T 0 1 _i 0 t t 1 1 ^ 1 t 1 0 1 1 1 1 1^ f_i 1 0 1 1 1 1 ■ j: 1 1 0 0 0 0 1 0 0 0 T 1 1 eo. IS— THE TRUTH TABLE for a 7'Segmen! LED display. 7-SEGMEHr LEOOlSPLffif B BCD INPUT < ^ SIGNAL BCD TO DECODEa' DRIVER O u F\G. 21— BASrc CONNECTIONS for a BCD-to-7-segment LED-display de- coder driven eCO SIGNAL DISPLAY BCD SIGNAL DISPLAY D c B A D c B A ; Q 0 0 0 0 t D 1 ' J ~ 0 0 a 1 0 1 1 0 I" 0 0 1 0 0 1 \ 1 i 0 0 1 1 \ 0' 0 0 CO 0 1 1 0 0 1 0 0 ; 1 ' 1 FIG. 22— THE TRUTH TABLE of a BCD*to-7-segmen! LED-display decoder driver 7-SE6MErn COMMOflAliODE LED DiSPLAir (CURRENT- > > > > LIMITING Bl;: < < RESISTORSI la lb BCD ^ 9 INPUT <^ SIGNAL^ m R7 COMMON-ANODE DECODER-DRIVER IC. BCD ^9 input / 4r SIGNAL 1 o_ COMMON-CATHODE DECODER'DRIVER IC Rt (CURRENT- LIMirrNG REStSTORSJ R7 7-SEGMENT COMMON-CATHODE LED DISPLAY FIG* 23— HERE'S HOW to drive a com- mon-anode 7- segment LED display. type of alphanumeric display is the y-se^Jincnl LED or LCD dis- play as shouTTi in Fig. 17. The segments are labeled a-g. and the dceimal point is labeled dp. You can display either the digits 0—9. or the letters A— F (a mix- ture of upper and lower case let- ters), as shown in Fig. 18. Most 7-segment LED displays need at least nine external con- FIG. 24-HERE'S HOW !o drive a com- mon-caihode 7-segment LED display. nections. Seven of those con- nections access the segments, one the decimal point, and the eighth is common, if the display is an LED t>pe, the seven seg- ments are arranged as shown in Figs. 19 and 20. A common- anode version (Fig. 19) has all LED anodes going to common* while a common-cathode ver- sion (Fig. 20) is configured in SCO SIGNAL DEOTCaf OftlVEB 2 i t ^ b c d V 1 , 1 . 0 7-SIGM£flt mspLfi^ dJTHJT fiPl (SQUARE VWartJ FIG. 25— HERE S HOW to drive a liquid- crystal display (LCD). the reverse format, 7-segracnt display/driver A 7'scgmcnt LF.D display gives llic output states of digital IC"s such as decade counters antl lattiics. They arc usually I ri- le rnally arranged in 4 -bit bin- ar>^-coded decimal (BCD), and cannal directly drive a display A special IC calleda BCD-to-7-seg- menl LED-display decoder/driv- er most go between the BCD and the display, as shown in Fig. 2L to convert BCD to a suit- able form. Figure 22 shows the rela- tionship between the BCD rep- resentation, and the 7'segment LED-display digits. Normally BCD-to-7'Segment LED-display decoder/driver ICs are available in dedicaled form syllable for driving only a special class of displays, whether I lie display is an LCD. or a common -anode or common-cat liode LED display FigLires 23—25 show how such 7-scgmcnl LED displays and BCD-to-7-segmcnt LED-display decoder/driver IC s are con- nected. Figures 23 and 24 show how to drive common*anode and cathode 7-segment LED dis- plays. Note that if theBCD-to-7* segment LED-display decoder/ driver IC outputs are un- protected, as is the case in most TTL ICs, a resistor in series with each segment limits cur- rent: most CMOS IC s have such resistors internally. In Fig. 25 you can see how to drie an LCD. The common or backplane (BP) display terminal is driven with a symmetric square-wave, whicli is derived from the phase output terminal. R-E HARDWARE HACKER Using the IC Master; wavelets update; another caller-ID chip; musical note frequencies; and piano and organ resources. DON LANCASTER Several commercial products are starting to appear using that great Rohm BA-1404 FM stereo transmitter circuit. In par- ticular, check out the Pioneer CD- FM^I and the Sony XA7A CD to auto radio adapters. Dealer cost is in the $42 range. What they do is let you play the output of a CO player through your existing car radio and audio system. The stereo channels are accepted by the BA-1404 iC and converted to a miniature but quite high-quality FM "broadcast" signal. You unplug your antenna, plug in your adapter, and then plug the antenna back into the adapter. Presto. Your CD audio now appears on the FM deal on your choice of one of two pushbutton- selected low-end channels. As we've found out in the past, sloppily breadboarded BA-1404 chips tend to drift and mistune so much that they are unacceptable to most of the newer synthesized FM receivers that demand perfectly on- channel signals. While the ultimate way to stabilize an FM transmitter is to use a frequency-locked loop against a crystal reference. Pioneer and Sony both seem to have gone a simpler route. Apparently they are just using a rigid and welf-shielded design, tight supply regulation, and careful tem- perature compensation instead. They seem interested in a very fow- level signal on a controlled cable, and they also do not see any anten- na coupling or loading effects, I will present more on those two beasties after 1 get a chance to test them. Either one of them should hack beautifully into a FM stereo wireless broadcaster circuit. Wavelets update We've had bunches of requests for lots more wavelet information. So, here is a summary of where we seem to be. Wavelets are a stunning new set of math tools that are having a strong impact on just about every region of advanced scientific study While the keenest interest in wave- lets now lies in video compression, wavelets are being applied to every- thing from cardiology and seis- mology to animal vision — and everything in between. Wavelets are a newer method of analyzing any complex set of signals and extracting useful information fn^m those signals. Unlike the an- cient Fourier Transform, wavelets have both global and local proper- ties that let you selectively zoom in on signal portions of interest- For instance, good old Fourier is quite superb at working with the top and the bottom of a square wave. But the sides give it fits. Instead of Fourier's "one size-fits-alL" wave- lets let you apply lots of detail only where needed. Wavelets tend to work in a "log" manner rather than in that "linear" fashion of Fourier This lets you pick up any fine details when wanted. Wavelets are also great at doing the "big lumps first/' That becomes handy in decompressing pictures, where your crude (but complete) picture initially appears and detail gets added later It also gives you the ability to select the amount of needed detail on the fly. One detailed book on wavelets is Wavelets and their Applications, as published by Jones and Bartlett, NEED HELP? Phone or write your Hardware Hacker questions directly to: Don Lancaster Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 The topics thoroughly covered in- clude wavelet fundamentals, video compression, digital signal process- ing, numeric analysis, and a bunch of advanced subjects. Sadly, the volume is written by math freaks for math freaks. It tends to run rough- shod over mere mortals. But it is there and certainly is the precise center of the emerging wavelet uni- verse. One tad less formidable wavelet summary tutorial and bibliography appears in lEEE-SP (Signal Pro- cessing) magazine for October 1991 on pages 14-38. Note that there are dozens of different monthly IEEE publications. Make sure you get the right one. For a useful collection of freebie reprints on wavetets for video com- pression, hardware chips, and de- sign software, contact the folks at Aware. Wavelets do video compres- sion far simpler, far faster, and with far fewer artifacts than the older (and now largely obsolete) DOT (discrete cosine transform) com- pression transforms. Their hard- ware is also far cleaner and more likely to be standard, Fmally, I have posted some great IBM wavelet shareware on my GEnie PSRT as the fife #365 WAVELET.PAK. You can call (800) 638-9636 for your connect informa- tion. A new caller-ID circuit Motorola has just intn^duced an ^ exciting new phone-caller identifica- §. tion chip called the MC145447. ^ Free samples are available. They ^ also have a very convenient but g' somewhat overpriced $100 evalua- tion kit breadboard that gives you a m full telephone-to-computer serial m- o terface. | Figure 1 shows one of many pos- 8 sible circuits. This one is intended for continuous powering. Compared to the earlier chips. 73 FIG. 1— ANOTHER CALLER ID CIRCUIT uses the brand new Motorola MC145447. Features include internal ring detection and data header stripping. Free samples are avai table. The service has to be available from your local phone company before this chip can be used. the MCI 45447 includes internal ring detection, and it apparently can be used without an expensive coup- ling transformer It optionally strips off that ID header and provides only *'rear" message bits. That's the dif- ference between their raw data out- put (the entire calier-ID byte sequence) and the cooked data (only the useful bytes) message strings. Note that those two 500-pF input capacitors must be closely matched and rated to at least 1500 volts. A varistor and the normal part-68 interface should precede the circuit. The output levels are TTL- or CMOS-compatible, but have to be suitably translated to be sent over a RS 232 serial cable or data line. The crystal used is the standard for colorburst frequency, available for under a dollar through several of our Radio-Electronics adver- tisers. Naturally, your caller-ID service must already be provided by your phone company before either the NEW FROM DON LANCASTER ^ 1 HARDWARE HACKER STUFF Hardware Ha^kor Reprints II or I El 24.50 Klldnlght Engine erEng Roprlnts 16.50 Incre dl b Ee 5e ere 1 1^ on«y Mac h Ene 1 8.5 0 CMOS Caokbool( 24.50 TTL Cookbook 24.50 Active Ftttftr Cnokbock 19.50 MEcro Cookbook voE I or EE 19.50 Lanoasier CEasslcs Library 109.50 AppEeWfEler Cookbook 19,50 POSTSCREPT STUFF A$k The Quw ReprEnts E, EE or EEE 24.50 LAserWrEter Secrets (Ete/Mao/PCj 29.50 P 0 stScrE p t S El & Te! E 39.50 Entro to PostScrEpt VHS VEdeo 39.50 PosiScrEpt BagEnner Stuff 39,50 PostS^rEpt Cookbook (Adobe) 16.50 Post ScrE p t Re r. Ma nu D E E E (Adobe) 28 .5 0 PostScrEpl Pfogram DasEgn (Adobe) 22.50 Type E Font Formal (Adobe) 15.50 LaserWriter Retofonce (Apple) 10.50 ReaE Wof Ed Postscript (Roih) 22.50 Po^tScrEpt Vbusi Approach (SmEth) 22.50 Th f nh E n g E n Po stS cr lp\ { Reid ) 22 .50 Undst PS Pgrmmg (HoEtzgang) 26.50 Tbe Whole Works {a1E PostScript) 349.50 BOOK-ON-DEMAND STUFF Book-on-demand raaource kit 39.50 GEnEe PSRT sampler (Ele/Mac/PC) 39.50 ^FREE VOICE HELPLENE VESA/MC^ chip or the evaluation kit will work. If the service is not yet available, suit- able machine language emulation software can easily be written for nearly any computer. The game paddle port on an Apple lie is abso- lutely ideal as a fake source of !D coding signals. We'll be seeing much more on this chip and suitable emulation software after I get a better chance to test it more thoroughly The ob- vious thing to do is to "stear' enough power off a computer's RS-232 interface lines to eliminate any need for a stand-alone power supply Internal power-down fea- tunes of the MC145447 can greatly simplify this task. Stay tuned for more details. The IC Master Identifying the maker of an Inte- grated circuit from just the part number can be tricky, especially if you are mistakenly reading the date code instead. As you have probably foundouton your own. Radio Shack has a useful Semiconductor Refer- ence Guide available for $4. We've already seen that the two leading sources of service, repair and replacement semiconductors are NTEand ECG. Parts and training specific to RCA and GE products are also available through Thomson Consumer Electronics Publications. This is an extension of the old "SK" series of replacement parts. But the place to go for informa- tion on integrated circuit part num- bers and cross references is a three-volume set known as the IC Master which is published by those Hearst Business Communications folks. The set is not cheap — it costs $160. Hearst also publishes the fine Electronic Products magazine, plus their EEM (Electronic Engineers Master Catalog) dinec tones. Both of these are free to qualified sub- scribers. But note that EEM and the IC Master are two totally different and separate sets of references. Top-octave generators This topic is more in the realm of "whatever happened to..," than anything else. But we still get lots of helpline calls concerning top-octave generators, especially in the Mostek MK50240 family The bat- tom line: They're long out of date. They also have recently become im- possibly difficult to get. The traditional western musical scale is based upon twelve equally SYNERGETICS Box a09-RE Thatcher, AZ 85552 (G02) 429-4073 octave 0 octave 1 octave 2 octave 3 octave 4 octave 5 octave 6 octave 7 octave a B 30.868 61 .735 123,47 246.94 493.88 987.77 1975.5 3951.1 7902.1 A# 29.135 58.270 116.54 233.0S 466J6 932.33 18647 3729.3 7458.6 A 27.500 55.000 110,00 220.00 1440.00 880.00 1760.0 3520.0 7040,0 G# 25.957 51.913 103.83 207,65 415.30 830.61 1661.2 3322.4 6644.9 G 24.500 48.999 97,999 196.00 392.00 783.99 1568.0 3136.0 6271 .9 F# 23.125 46.249 92,499 185.00 369.99 739.99 1480,0 2960.0 5919.9 F 21.827 43,654 87.307 174.51 349.23 698.46 1396.9 2793.8 5587.7 E 20.602 41.203 82.407 164.81 329.63 659.26 1318.5 2637.0 5274.0 D# 19.445 36.891 77.782 155.56 311.13 622.25 1244.5 2489.0 4978.0 0 1B.354 36.708 73.416 146.83 293.56 587,33 1174.7 2349.3 4698.6 cu 17.324 34.648 69,296 138.59 277.18 554,37 1108,7 2217.5 4434.9 c 16,352 32.703 65.406 130.81 261,53 523,25 1046,5 2093,0 4186.0 RG. 2— THE STANDARD FREQUENCIES of the Western 12-note equally tempered musfc scale. It applies to most electronic and Donvenllonal musical instruments EXCEPT the piano. Ptano keyboards must be ''stretched'* because of a piano's non- harmonic overtones. tempered notes per octave. (An oc- tave is a 2:1 frequency interval.) Each note is related by the twelfth root of two, or 1059 times the fre- quency of its neighbor. The notes, of course, are lettered asC,C#.a D#. E. RF#,G.G#. A. A#, B, and back around to the next C. one octave higher The tradi- tional organ people number the oc- taves from zero up through eight. The usual "standard pitch" frequen- cy reference sets note A4 to pre- cisely 440.0 Hertz. The usual twelve- note-per-octave equally tempered frequencies ap- pear rn Fig, 2. Because all of the music note fre- quencies are in^ationa!, they have lo be approximated. One way to do that is to take a high-frequency clock and divide it down by magic numbers which can hit the needed accuracy. Musicians define the in- terval between notes as one semitone, and further define one percent of a semitone as a cent A one-cent frequency error is approxi- mately 0.06 percent. Reasonably trained individuals usually can spot a three-cent fre- quency error, while the best of pro- fessional musicians can resolve a single cent. Thus, the relative fre- quency accuracy of all the notes PIANO AND ORGAN RESOURCES DevtrOREcs 6101 Warehouse Way Sacramento, CA 95826 (916) 381-6203 CmCLE 3Q1 ON FREE INFORMATION CARD JrnI Audio Engineering Soc 60 East 42nd Street, Rm 3520 New York City, NY 10165 (212) 661-2355 CIRCLE 302 ON FREE INFORMATION CARD MfX Bookshelf 6400 Mollis Street, Ste 12 Emeryville. CA 94608 (800) 233^9604 CIRCU 303 ON FREE INFORMATION CARD PAIA Electronics 3200 Teakwood Lane Edmond, OK 73013 (405) 340-6300 CIRCLE 304 ON FRES INFORMATION CARD Player Piano Company 704 East Douglas Wichita, KS 67202 (316) 263-3241 CIRCLE a§5 ON FREE INFORMATION CARD Tuners Supply 88-94 Wheatland Street Somerviiie, MA 02145 (800) 247-0702 CIRCLE 306 ON FREE INFORMATION CARD No Better Probe Ever at this Price! Shown hure ^Ai\ Model SPI5{)Switchuhlc lx-lO?^ ...Z 4" Risetiine less than L5 nsec. rcpljtcTJicnt'i fur Tckironj\. H-P. * Universal Works with all oscilloscopes • Rugged Flexible cable lasts longer- RepijtL cable ground lead • KttHUHuical S 11 bs I an I i a I sav i n gs compared to OEM probes • 10 Day Rclum Policy Guaranteed perrorinance and t|ualiiy H TEST [TPI PROBES JNC, 'in 9I7K Brown IXxT Ruad. San Diego, CA 92121 I nil Friie l-H0»-3fiH-5719 IP Q. 9 m B CIRCLE 123 ON FREE INFORMATION CARD 75 NAMES AND NUMBERS Aircraft Designs 25380 Boots Road Monterey. CA 93940 (408) 649-6212 CIRCLE 307 ON FREE INFOHMATtON CARD Antique Electronic Supply 6221 South Maple Avenue TempG, AZ 85283 (602) 820-5411 CIRCLE m ON FBEE INFORMATION CARD ARclad PO Box 100 Glen Rock. PA 17327 (717) 235-7979 CIRCLE 309 OH FREE INFORMATION CARD Astex 35 Cat>ol Road Vtobum. MA 01801 (617) 933-5560 CIRCLE 31 Q ON FREE INFORMATION CARD Aware One Memorial Drive Cambridge, MA 02142 (617) 577-1700 CIRCLE 311 ON FREE INFORMATION CARD ECG/Philips PO Box 3277 Wjllramsport, PA 17701 (717) 323-4691 CIRCLE 312 ON FREE INFORMATION CARD EMC Technotogy PO Box D Gainesville. VA 22065 (703) 347-0030 CIRCLE 313 ON FREE INFORMATION CARD GEnie 401 North Washington Street Rockville, MD 20850 (800) 638-9636 CIRCLE 314 ON FREE INFORMATION CARD 10 Master/Hearst 645 Stewart Avenue Garden City. NY 11530 (516) 227-1300 CIRCLE 31S ON FREE INFORMATION CARD IEEE/Signal Processing 445 Hoes Lane Ptscataway, NJ 08855 (908) 981-0060 CIRCLE 316 ON FREE INFORMATION CARD should be better than 0.06 percent. To get all of the notes to sound weil together, well-chosen "magic" division ratios must be used. Figure 3 shows Sonne detaiL Of all the pos- sible 8-bit divisor values* only the rrWFastex 226 Gerry Drive Wood Dale, I L 60191 (708) 350-8200 CIRCLE 317 ON FREE INFORMATION CARD Jones & Bartlett 20 Park Plaza Boston. MA 02116 (617) 482-3900 CIRCLE 318 ON FREE rNFORMATlON CARD Media Magic PO Box 507 Nicasio, CA 94946 (415) 662-2426 ORCLE 319 ON FREE INFORMATION CARD Motoroia PO Box 1466 Austin, TX 78767 (800) 521-6274 CIRCLE 320 ON FREE INFORMATION CARD NTE Etectronics 44 Farrand Street Bloomfieid. NJ 07003 (201) 748-5089 CIRCLE 321 ON FREE INFORMATION CARD Rotim PC Box 19681-631 Irvine, CA 92713 (714) 855-0819 CIRCLE 322 ONFHEE INFORMATION CARD Signettcs/Phllips 611 East Arques Avenue SunnyvaJe. CA 94088 (800) 227-1817 CIRCLE 323 ON FREE INFORMATION CARD Synergetics PO Box 809 Thatcher, AZ 85552 (602) 428-4073 CIRCLE 324 ON FREE INFORMATION C ARD Thomson Consumer Publictns 2000 Clements Bridge Road Deptford, NJ 08096 (609) 853-2417 CIRCLE 325 ON FREE INFORMATION CARD Vdltek 100 Shepard Street Lawrence. MA 01843 (508) 685-2557 CIRCLE 326 ON FREE INFORMATION CARD unique sequence of 116 123 ... 232 is good enough for a three-cent worst -case accuracy. If you have more bits avatiable. then other se- quences are also usable. Figure 4 shows you how a top- The 12 equally tempered mustcai keys repeat each OCTAVE, or 2:1 frequency interval. This means each note is retated to Its neighbor by a geometric ratio of lha 12th root of two, or 1.05946:1 Only this "magic* sequence ot 8-bil divisors is good enough to iBl all of the notes sound good together... 232 219 207195 184 174 164 155 146138130 123116 Here is the better 9-bit "magic* sequence used by the MK50240„. 478 451 426 402 379 358 333 319 301 284 263 253 239 FIG. 3— EQUALLY TEMPERED NOTES are irrational, so only thts one ''magic'' S-bit sequence of division ratios can be a good enough approximation. octave generator works. This is ar old N-channel integrated circuit tha' runs on a single 12-volt supply. Ar tnput clock of 2.000240 MHz is re quired. The clock can be obtainec from a crystal for an abso(ule refer enee. or it can be variable for pitcf blending or keyboard stretchinc variations. Thirteen outputs are pro vided. giving you all the notes of the highest octave, plus a spare C ar octave lower. To generate lower notes, you car either divide down the input clocl- for a single octave, or else add out put dividers to generate the entire music k^board as shown in Fig. 5 Hackers have long ago found lots of other exciting uses for top-octav€ generators, which include musi cian s pitch references, piano tuninc aides, meditation, and musical toys Perhaps one of the most off-the wall new-age uses involved John Si monton s chord egg. Polyphonic chords obtained from a lowered pitch top-octave generator wer€ chosen at random and routed to £ stereo headset. With suitable dela) and phasing techniques, the appar ent source of the stereo sounds is forced between your ears, and the chords literally bounce arounc inside your head. A few chord eggs remain available thnDugh PAIA elec tronics. Assembly details for a traditions top-octave generator music module system appeared long ago in the June 1976 issue of Popular Else truntcs^ 0000606 0 600 on D D# E F F# G G# A A# B OUTPUT TONES FIG. 4 — TOP OCTAVE GENERATOR inlegrated circuits produce all the needed notes of the musical scale, Input or output lines can be binarily divided for lower octaves. Sadly, these chips are getting hard to find. There are several reasons why the top-octave generators are no longer popular The "locked in" nature of octave-shifted notes sound as a single richer tone, rather than as a separate pair of chorused voices. Having all the notes sound- ing continuously in the background can lead to serious systenn noise problems. Zillions of wires are needed because the keyboard is usually non-scanned. The envelope and voicing opportunities are also severely limited. based and all-digital sampled syn- thesizers do a much better job with a far cheaper a far simpler, and far cleaner system architecture. More- over they are infinitely more flexible and sound much better than any- thing else. At any rate, new sources of top- octave generators seem to be long gone. A very few of the orfginal chips may remain available through PAfA or Devtronix on a catch-as- catch-can basis. It should also be possible to fake the top-octave gen- erators with programmable gate ar- ray devices. The FPGA costs are dropping rapidly enough to make this possible. Note that any pitch reference must be a nearly pure sine wave. Any higher harmonics will fool the ear and also cause potential tuning problems. Finally, if any of you out there know of any secret stashes of thfs one-time great chip, be sure to let alt of us know. Try the bulletin board system (RE-BBS) 516-293-2283 Tlie mQfe you use it the more useful it becomes. We suppDil 1201] arid 2400 baud operation. Paramelers: SN1 (8 tiaia bits, m parity, 1 sipp bit) or 7E1 j? data bils, even parity. 1 stop bit). Add youfseif to our user fifes to Increase your access, Communicele witfi other H E readers. Leave your comments on R-Ewltfi the SYSOR RE-BBS 516-293-2283 Be an FCC ' LICENSED ELECTRONIC TECHNICIAN! I No costly school. No crom muting to class. The Original Home-Study course prepares you for the "FCC Commercial Radio- telephone Licensc'^This valuable Hcerise is your professional ^'ticket*' to thousands of excitinij Jobs in Communications. Radio- TV, Microwave, Maritime. Radar, Avionics and more..* even start your own businessf 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 j^et your FCC License or money refunded. Send for FREE facts now. MAIL COUPON TODAY aSmmdnD VRO^ulnlorir FCC LICENSE TRAJNING, DepL 90 RO. Box 2824, San Francisco, CA 94t26 Please rush FREE details immediately! MAM£ ^ ADDRESS CITY . STATE . 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JERROLD-TOCOM-ZENITH HAMLIN-OAK-PIONEER SCIENTIFIC ATLANTA •24 HOUR SHfPMENTSI -MONEY BACK GUARANTEEi • QUANTITY DISCOUNTS I MASTER CARD / AMEX / VISA / C.O.D, Have make 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 j CIRCLE 134 ON FREE INFORMATION CARD rTTTTTTTTTT From lower octaves: To lower octaves FIG. 5— A TRADITIONAL ELECTRONIC ORGAN architecture using top octave genei ators and dividers. Today's MIDI-based sampfed synthesizer circuits can produc much better sound far simpler and In an infinitely wider variety. Piano and organ resources I thought I'd gather together some traditional nr^usic names and numbers for this month s resource sidebar For piano tuning materials and supplies try Tuner's Supply. while the best source for antique instrument parts and data is the Player Piano Company. Andagood horse's mouth book is Piano Tuning and Allied Arts. Note that piano tuning is CI) a lot harder than it appears; C2) a min- uscule, unprofitable, and rapidly de- clining market; and C3) an easy way to cause irreparable damage. Note also that most piano key^ are ^ever tuned to ail their "correct' frequencies, instead, the keyboarc has to be "stretched" to aliow fo the non-harmonic nature of rea world string overtones. Keep ir mind that il takes several weeks U properly tune a ptanol One classic organ kit company i! Devtronix, while a company calfec PAIA offers a wide range of trads tional to new age kits. An excellent source for electroni( music titles is the MIX Booksheil stocked by the folks that also pub Itsh the Electronic Musician maga zine. Fundamental synthesizer se- crets can often show up first in the Journal of the Audio Engineering Sociely. Some additional electronic music resources appear in my Hardware Hacker tl reprints. New tech lit A great "gottahave" is the Video Data Handbook from Signetics Phi- lips, which is chock-full of digital vid- eo-interface chips, RGB digitizers, multimedia chips, sync strippers, color decoding, and ail of the usuai A/D and D/A conversion chips and circuits. Speaking of multimedia, the Media Magic people offer a Computers in Science and Art cata- log full of good books, tapes, and software, A free l^ibliography of papers on microwave plasma applications is offered by Astex, From Antique Eiectronic Supply, a 1992 wholesale catalog of sup- plies, books, tubes, info, and parts for the electronic collector We Ve had lots of calls from experimenters trying to find Fahnstock clips in this day and age. These folks are one of the few remaining suppliers. Another trade journal on magnet- ic and electric shielding ideas is EMC Technology. And a wide selec- tion of aircraft hacker books is avail- able by way of Aircraft Designs. This month's freebie mechanical sampies include foams, films, and foils from ARclad, a Foam Specifier Kit from Voitef<, and some self-stick bumpers from ITW/Fastex. A reminder that I have recently revised my Incredible Secret Money Machine tl and have autographed copies on hand for you when you cait or write. You can get the ISMM by itself or as a portion of my Lancaster Classics Library. You can also reach me via GEnie PSRT C800) 638-9636 where you will find hundreds of downloadable files and tutorials on hardware hack- ing and also those midnight engi- neering topics. Our usual reminder here that most of the products and services that have been mentioned appear either in the "Names and Numbers" or in the "Piano and Organ Re- sources" sidebars. R-E CREATE IMTELLIGENT PROJECTS WITH THE VERSATILE Z8 PROGRAMMABLE MICROCOMPUTER. This powerful comput- er was designed for fiexibiiity and can be used for various electronic projects. I'O Intensive. Up to 20 MHz operation. 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CIRCLE 115 ON FREE INFORMATION CAFID S495 FOR A PROGRAMMABLE DC POWER SUPPLY IS NOW A REALITYl • GPIB Interlace Standard • Output Voltage' Current Programming d Readback • Local & Remote GPIB Operations • Remote Sense Function • Programmable Qven/oElage and Overcurrent Protection ♦ Software Calibra- tion • Superior Line/Load Regulation • Output Enable/Disable • 3 Year Warranty FREE Orientation Video aval lab Ee. For de- tails, call: AMERICAN RELIANCE INC. BOO-654-9838 FAX: 818-575-0801. CIRCLE 185 ON FREE (NFOFtMATIOK CARD CABLE TV CONVERTERS AND DE- SCRAMBLERS SB-3 $79.00 TRl-BI $95.00 MLD-$79.00 M35B S69.00 DR2-DIC S149.00. Special combos available. We ship COD. Quantity discounts. Cali for pricing on other products. Dealers wanted. FREE CATA- LOG. We stand behind our products where others fail. One year warranty. ACE PROD- UCTS. RO. Box 582, Saco, ME 04072 1 (600) 234-0726. CIRCLE 75 ON FREE INFORMATION CARO APPLIANCE REPAIR HANDBOOKS— 13 volumes by service experts; easy-to- understand diagrams^ illustrations. For major appliances (air conditioners, refrigerators, washers, dryers, microwaves, etc.), eEec, housewares, personal-care appliances. Basics of solid state, setting up shop, test instruments- S2.6S lo $5.90 each. Free brochure. APPUANCE SERVICE, PO Sox 789, Lombard. IL 60148. 1-(312) 932-95S0. CIRCLE 84 ON FREE INFORMATION CARD TWO FOR THE PRJCE OF ONE' 5 MIN- UTE ASSEMBLyi MONEYBACK G U AR ANTEE! Attach any 3V 1 2V battery and have the most stable, sensitive^ powedul room transmitter you can buy- Or attach to telephone line. Hear all tele- phone conversations— crystal clear- over 1 mile away without batteries! Use any FM radio or wideband scanner. aO-130 MHZ. lOOmW output! VT-75 mi- crotransmitter chip S49.95 - 1.50 SStH. VfSA. MC. MO, CODs add S4.00. DECO INDUSTRIES, Box 607, Bedford Hills, NY 10507. 1-800-759-5553. CIRCLE 127 ON FREE INFORMATION CARD AUDIO UPDATE AES: Audio Fact and Fantasy, LARRY KLEIN The theme of the recent 91 st Audio Engineering Society Convention heid in New York — 'Audio Fact and Fantasy" — was one dear to my heart. I thor- oughly enjoyed both the formal ses- sions and the lunches and hallway conversations with some of my old friends and new acquaintances. As I've done in years past, I intend to discuss some of the more inter- esting papers. But first, I'd like to set the stage, so to speak, with a recapitulation of what I see to be some of the basic problems of high- fidelity reproduction— which is what the 91st Convention was all about. What's the Problem? In the very early days of hi-fi we kept talking about "concert-hall re- alism." Later, it came as a shock to many of the audio faithful to read that some new or rebuilt concert flails failed to achieve the "realism" supposedly inherent in live sound. In any case, how can the live listening experience ever be even approxi- mately duplicated by scattering a dozen or more microphones throughout the ranks of a strangely grouped orchestra? And then when pop recording went multi-track, fre- quently done in several venues over weeks or months, the philosophical problems of duplicating a live sound that never was became intense— at least for the thinking listener Those and other questions arise during the process of getting the music into the storage medium. Ex- ^ tracting the music out again and de- ^ livering it to the ears of a listener in believable form is the other side of ^ the coin, Thesuccessof a recording o can only be judged during playback, g But playback through what equip- uj ment, into what environment, and % with what jury of listeners? cc A recording of a live event entails a selected sampling of the sound field in the recording environment, go The success of the sampling pn3- cess — which basically involves the choice and placement of micro- phones — depends mostly on the talent of the recording engineer If under reasonable playback condi- tions the recording can produce a plausible simulation of a live sonic event, it is deemed a success. Be aware that this thumbnail in- put-output description of the audio process leaves many questions un- answered. Not unexpectedly, the in- put part of the recording process excites far fewer passions than the playback end of things. In playback, the audiophite gets involved ob- sessively exploring the real or imag- ined effects produced by each of a wide range of components. Objec- tively, most electronic equipment is B 0.75m t^-^"^ 0,75m DRAPES "l"^ J;C(+0,6m) 1.3m 6 D SCREEN HEIGHT: 2.Bm -I- 1 LOUDSPEAKER _ AiMms pom 4 I i JL I 2.4m 0.9m GIOSED CABINET 1.0m I 0.6ni 0.9m CLOSED CABINET, BOOKSHELVES ABOVE K OPERATOR'S CHA!R FULL'HEISm^CLOSID-i CABINETS : FIG. 1— THE FLOOR PLAN of the Nation- al Researoh CounciJ of Canada's speak- er listening room shows loudspeaker and listener locations. Loudspeakers were placed at positions 3, 4, 5, and 6 in monopfionlc tests, wilh listeners at po- sitions 1, 3, and 5. In stereophonic tests^ loudspeakers were at position B and D, and listeners at positions 2 and 5. really very good. Speaker quality however, is somewhat variable from mode! to model and brand to brand. A third category of equipment, ac- cessories, ranges from the some- times helpful through the silly to the truly demented. (For further explo- ration of that last category, browse through virtually any issue of The Stereophife and The Absolute Sound.) Loudspeakers It seems to me that amplifiers are pretty much cut and dried in the sense that competent designers can give them any desired sonic quality. Although I find it strange that an engineer would, deliberately in- troduce — or fail to eliminate — non- linearities in an amplifier design, I know for a fact that this has some- times been done in the misguided pursuit of euphonic Cear-pfeasing) effects. In any case, it's not that difficult to produce a virtually per- fect amplifier, which is defined as one being free of audibly disturbing artifacts. Loudspeakers are an altogether different ball game. Their complex- ities are reflected in the seemingly endless series of technical papers, experiments, and products pro- duced over the years. The recent AES Convention provided an excel- lent overview of the raging contro- versies and unsolved problems still besetting the world of loud- speakers. The essential questions confronting the loudspeaker de- signer are: What should a loud- speaker do. and how can the designer determine when it's doing it correctly? A comprehensive, if somewhat weighty, overview of those speaker evaluation problems was presented by M,R. Jason of National Public Radio, ril discuss some of the is- sues raised by Mr Jason. The listener-preference approach as a means of evaluating loud- speaker performance would seem on the face of it to be an easy way to separate the good from the bad from the indifferent. But unless the evaluations are based on very care* ful procedures and sophisticated statistical analysfs* rather than sim- ple listening tests, the results are likely to be misleading. In fact* listener preference ap- pears to be so unreliable an &/alua- tton tool that a number of reputable academic researchers have sug- gested that listener-preference tests be replaced by detectable-dif- ference tests. Those would test the ability of a listener to discriminate between a lest srgnal and a refer* ence signal. The thought seems to be that preference is detennined by too many uncontrolled subjective variables* while "detectability" at least eliminates individual taste from the equation. "Deteclabilily" also eliminates some of the problems of fasl- Fourier transform lime^delay spec- trometry. One of the eadiest users of the technique confided to me at one point that while the displays were undoubtedly impressive-look- ing and contained lots of informa- tion about what was happening during the first several nr^ilHseconds of a pulse, the exact relevance to the music-reproductive abilities of ^ny particular speakers was. at best, unclear A Standard Listening Room No one argues that loudspeaker performance is independent of the room in which it is pfaying. Even if /ou had an ideal speaker — what- ever that is — the relative balance of the high and low frequencies, the evenness of the distribution of sound throughout the room, is strongly influenced, for batter for worse, by the room size, propor- tions, wall treatments, furniture^ speaker location(s), and listener po* sitions. All of those variable have to be standardized before evaluations can be meaningful to others who are working — or listening — with a dif- ferent set of conditions. A major step toward standardiza- tion was taken in 1985, when the International Electrotechnical Com- mission ClEC) specified a standard listening room when it published tts recommended practice for listening tests. Listening Tests on Loud- speakers publication 268 13. The standard room was not. as one might suppose, derived from some mathematically optimized ideal acoustic environment. It was based, instead, on a 22 x 13,5 x 9.2-foot room, shown in Fig, 1. used for lis- tening tests at the National Re- search Council of Canada in Ottawa. CThe NRC roughly corre- sponds to the National Institute of Science and Technology in the U.S., but does far more practical research in support of various Ca- nadian industries. The NRC test and research facilities are largely re- sponsible for the general excel- lence of Canadian loudspeakers — but that's another story for another month J The room's acoustics were ad- justed somewhat with drapes and upholstered chairs. I visited the room shortly after it had been set up and I remarked on its acoustic nor nrralcy. It was explained that it was intended to represent a good do- mestic listening environment typical of North America and Europe. Re- verberation time is 0.35 ± .085 seconds from 250 Hz to 4 kHz, ris- ing to 0.85 seconds at 40 Hz and falling to 0.25 seconds at 10 kHz. Having a common roference en- vironment for speaker listening tests is a necessary tool, but cer- tainly only part of what needs to be done. Without going further into the complexities of speaker evaluation, let it suffice to say that it is no easy task — and certainly not as easy as most audio publications would have you believe. Floyd Toole* formerly of the NRC. has done significant work in correlating listener evaluations with measured performance. In the view of many experts* Toole's efforts have advanced audio art sig- nificantly toward the goal of ■"What you hear is what you measure^and vice versa." Next month. 111 look at some ad- ditional AES papers that 1 think you1l find interesting. R*E LEARN . to ClBvV MAINfTAIlV RffAIR CAMCORDERS .(IhI h onk ritjuirt'im-iH iiH vntif v» tt»'K^' fKcr t'f M I'l a /'.If nhjl liw t.M tiUftmtx id uriM i»riU^ ni.il'tiiH tnifK liirHT likf VC'K>I> jir iUiv mytmplv tnt^ 4 h.iilH itt Uithm-... IVv * -1*1 \ tnt ttt tw li t v^t^ih tt\ rhi ^ • in I't I Lf l( i\\ I r» I M h Mm .,in ,n i 'TMh* i i4 S H .i N !> H r. svliilt' wnrLinn; .tl hfititt'l' Ccl In NHW — Sf Hin iditH urikfv VkiW \h* Ui.t* Vl H.^, 1. 1'., tHH* m *ilri>i)%4 i'vt^v lK»n*i' I iir .M lUiii imftf I UMnin^ jril)V(>ii *■ *in(MriiSt>''t iMMur Ic^s llun iO fiiirtuft'H wnk, I III J ( .%nn e field that (nterests yo^i most See how easy Jl is 10 irain 3\ horne toi a great career Of advancemcnl in your preseni job 1 -800-234-9070 OR MAIL COUPON TODAY! Internatlanal CorrespTndence Schools" IT^'J DepL ADES22S, 925 Gait Street. ScranlOfJ. PA 16515 Pteasfl wnd etic \m facts, color brochitre and full tnfomiation on how 1 Ciiri r,tu[ly hDriic for tne camr I have ctiOS^n. Hd oblknlxjn CHECK ONE SOX ONLY! mOOATF IN SPtClALinO Bt;5]HtssDr[;iirE (w^rams lI duf UgrTH — f wet Optxn 1 ASSOCUT^ IN SPECIALIZED TEOMOUWr DtGR£E iftOCRAMS □ O/i EngKwrirg; Tecnnotogr^ □ MadoncatEnQVtttfino TsmAjoy pAcMtUKA* □ Swnnvio jnd Mjcpfig □ Condnonna 4 iMiginban □ f>DlciSpiraf □ . HAH or ^ " ai Ui Hi □ Annates DM CrtyiSUti -Zip. Our oscilloscope is shaping up nicely. RDBERT GRDSSBLATT If you're a regular reader of "Drawing Board. " you know that the principles of design are jiist as important as the particulars of the circuit. Even though each se- hes of columns winds up with a working gadget of one kind or othen the real idea behind all of it isn't to see how to design something in par- ticular, but how to design anything in general. The real message is the method, not the minutiae. /6 s CJ- pa 3 P/ £^ -fV CA /3 /6 /a / ^ 6 JC6 Cl^ jes GD MJ^ ^VC4 /J /4t IC 7'S a. /A I pS2, —T y o ^ a c £? A 3 C O 3^ s JL >f 30b o T , fcXc/-A. Of FIG. a^HERPS OUR OSCILLOSCOPE SO FAB. The NAND gate IC7-C is switched Into the Circuit rn the triggered sweep mode. It resets when the trigger signal puts a high on the second leg of the NAND gate. If we want the scope to be free running^ we switch the trigger le^ of the gate to ^ V< You should file this circuit away in •/our notebooks because it comes in landy when you least expect it. And or all you out there who were rained to eat absolutely everything :>n your plate, there are ways to rec- onfigure the circuit so you can use ^ry singie output of every srngle :hip. Without going into the details, he problem is to crBate some sort Df an external output enable control ox the 4017. That can be done with liuffers or transistors between the outputs of the 4017 and whatever he outputs are intended to control. But I leave that to you. Any more of these asides and 1 11 wind up wnt- ng like Lawrence Sterne did in Tn- stram Shandy — digression upon digression upon digression. By adding Fig. 2 to the stuff we did last month, we now have a work- ing version of the horizontal circuit we defined at the outset of this de- sign project. It does everything we specified and. if you wire it up on a breadboard, you "I! see that the only other piece you have to add is an eight-position, single-pole rotary switch Ca break-before-make type), so you can select the sv^eep speed being fed to the common clock in* puts of the 4017 s. Before we leave the horizontal section of the scope, this is a good time to talk about how the scope is going to be triggered. If you^re femil- iar with scopes, you know that most scopes offer you a choice of three basic ways to control the horizontal sweep: as a single shot, free-run- ning, or triggered. Each of them is useful in different situations and. with the exception of free-running (most scopes refer to this as "nor- mal"), the ctrcuilry to make them happen needs some of the signals well be generating when we get to work on the design of our scope s vertical drive. Any control of the horizontal sweep is dirBCtfy translatable into what we do with the reset control lines of the 4017 s. As you can see in Fig. 2. all the reset lines have been tied together and are controlled by contfnued on page 98 SELECT 5 BOOKS for only ^4- (values to $150.75) 84 Your most complete source for electronics books for over 25 years. counts as Membernus offers and special sales, with scores of titles to choose from. ■ Autonnatie Order,. If you want the Main Selection, do nothing and it will be sent to you automatical' ly. If you prefer another selection, or no t>ook at all, simp- ly indicate your choice on the reply forni provided. You will have at least 10 days to decide. As a member, you agree to purchase at least 3 books within the next 12 months and may resign at any time thereafter. * Ironclad No-FIIsk Guarantee^ If not satisfied with your books, return them within lOdays without obligation f • Exceptional Quality. All tx)oks are quality pubtlshers' editions especially selected by our Editorial Board. AM boQU AT* hmnHsmrm ur*ma nmtm 4 Iglkmct bf m *'P'* tor papmtMCk. €1992 £L£CTm)HJCS BOOK CLUO. 8iu« Ridpt Smrwni, PA >73M«10 Blue Ridge Summit, PA 17294-CIBlD n YES! Raas« accept my mofnoef^ip m Uie El«ctn^c$ Bock Out and send the 5 voktmes lisied betow. bilhng mo S4.95, It nol satisM. I may mum ihe books within ten days wttiout obligation and have my memt>efsti4p canc8l>«d I agt &o to purchase at Peas; 3 booH^ at r^ular Dub prices during the next 12 momiis and may resign any time Ih^reatt^. 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Leave your comments on R^E with the SYSOR RE-BBS 516-293-2283 PHONE^LINE MONITOR continued from page 58 TABLE 3— DECODED DTMF OUTPUTS liiffh-frequency tone groups, wliich are then decoded into one four-bit code per key» as shown in Tkble 3. The DTMF decoder informs the microprocessor when a tone has been detected by asserting 'rsTu. which drives bit 6 of port 1 of the 8031, shown back in Fig. 2. The 8031 then reads the 4-bit code by asserting t-ok through port CO of the PIO, and reading bits PB0-PB3 of the PIO. In addition to reading DTMF codes, the PIO also reads the status of configuration switch SI and off/standby switch S2, and can assist RS-232 data flow via the DTR output and the CTS input. Audible signaUlng The speaker driver is shown in Fig. 4-e, Digi-Call can gener- ate several different sounds, as follows, • Digi-Call produces a warble sound when the unit is turned on; it emits a beep when the user selects standby mode. Cannot be disabled. • Digi-Caii produces a ringing sound when the unit is on and the phone rings. Can be dis- abled. • Tlie turn-on reminder warble sound will chime every V-i hour when the unit is in standby mode. Can be disabled. • Power loss causes a short beep to be produced every min- ute. Cannot be disabled, • A RAM-full condition causes an alami to sound every minute until data is erased using the I^C^based utility program. Can- not be disabled, • Illegal configurations of SI cause a continuous slow-going high'low beep. Cancel by choos- ing legal switch positions. We'll discuss 81 further next Ume. The microprocessor has an internal serial interface that Digi-Call uses to transfer stored telephone data to the PC. How- ever, the microprocessDrs TVL levels are not compatible with standard RS-232 levels, so we use a MAX-232, shown in Fig, 4- DIGIT 03 02 01 DO i 0 0 0 1 2 0 0 1 0 0 t 4 Q Q 0 5 0 i 0 1 6 0 1 t 0 7 0 1 1 8 1 0 0 0 9 1 0 0 1 0 1 0 1 0 * 1 0 1 1 # 1 1 0 0 e, both to drive the RS-23:d lines, and to generate the ±9 voU signalling voltages. We alsc ^'steal" the - 9-vo!t DC output tc power op-amp ICl. Status indicators Three status LED s indicate Digi-Call's operational status. The green **On" indicatoi {LED4) lights steadily when the unit is on and the phone is on hook; it blinks when the phone line is off-hook or ringing. The red "Full" indicatoa (LED3) indicates that the date RAM is full and no further cal logging is possible. The "Full* LED also lights during the Power On Self Test (POST), anc during the diagnostics aceessi ble through the host PC soft ware. Last, LED3 blinks slowh if configuration switch SI is sei to an Illegal combination. The Watch Dog indicatoi (LED5) blinks slowly Linder nor mal circumstances, and rapidh if powered by the batteries. The power supply, shown ir Fig. 5, is designed to operate even in the absence of AC power Blocking diode D9 isolate; back-up cells B1-B6 while AC power is present; resistor R3] determines charge current inte the batteries. Digi-Call car function with nonrechargeabk batteries, in which case R3J should not be installed. Next time we'll build the unii and get it up and running. R-I 48 HOUR SHIPPING ELENCO & HITACHI PRODUCTS c/^T^r^e AT DISCOUNT PRICES 1-800.2927711 Hitachi RSO Series [Portable R«aMini« Dig^ai Slarsge Qs^CiliO&CDpes} S1,S95 S2J95 S2,995 ^.495 VC-6023 • ZOMHz, ZOMS/S VC^6024 * 50MH2, 20MS/S VC^6025 - 50MHI. 20MS/S VC-6045 ' lOOMHi. 40MS/S VC*6145 ' IOOMH1, IO0MS/S_ RSOs from Hitacfii feature ton mooe. avflrag-fig; ^ve moitiDry, smoothing, mlgrpolalion. preirlggdttnE^. cursor measurernents ThOfiO scopes enable mars accurate, sjmpilre'r obscrvulion of conrtF^iJK wavabrms. m addittan \q such runcllons as hardcopy via a plorior intertoca and wavflTorm tranafar vsa the RS'232C inteiffeica Enpy tho comfofl ol a/ia'oQ and tne power fo ^^gitaf 25MHz Elenco Oscilloscope SPECIAL BUY V-212 - 2OMH2 Scope S425 Hitachi Portable Scopes DC 10 50MHJ. 2-Choj*nel. DC otfsef func- llon, AllefTtate magnifier funclion V-525 - CRT Readoul, Cursor Meas. $995 ' Delayed Sweep S975 ■ Basic Modat SS76 ■ 40MHz S776 $695 S625 HJTACHl COMPACT SERIES SCOPES _ Tfis Mfws p^w^dK ffi&fiy r^w* ^jidc^.'^s syci &i CRT Ft«eaK.r!. Cursor nv**5ijrBfT>e rtts (V- 1 \ Ci65A'C>65A}. f ro- cjflncy Qr, (V-1(JflS). Sw«flptime Autwangfjvg, D«l*yvd sweep tvi Tnpper lock usang a 6-inch CHT.Yoj oofil r««3 ne conpoanflss in tffrms ai pfrrtomanca And pptraMui. V-660 ■ eOMHz. Dual Trace . V-665A * OT, w/cursor V-1060 ' 100MHz. DualTrace_ V-523 ■ V'522 V-422- - 2 DM Hz delayed swaep _ V-222 ' 20MHz deluxe $349 S-1325 ♦ Diraf Trace imV Sef5Sit(vjty • 6" CRT » X-Y OpefBiion • TV Sync 1 0x Pfobes indudecf PRICE BREAKTHRU! , Si. 149 SI ,345 . SI .395 V-1065A' 100MHI. DT, w/cufsor Si .649 V-1085 - lOOMHz, QT w/cursor Sl.995 V-1100A- 100MHz, Quad Trace. $2,195 V*tlSO - iSOMHz, Quad Trace S2,695 Elenco 40MHz Dual Trace "Good to e^QC 50MH1 20 MHz Digltol Storage OsciHotcope ft 2K KwofO p*r cnanflti msflvry DS203 • tOI4S/»umpkngni^ $795 # High lumiftarsce 6" CRT i • ^mVSensit^vrty | 1 J . 1 * 1 QKV AccaJefaikjn Vohage ' * Jf • 17ns Rise Ttme • in-iuGss (2) Ix. tOx Probes ]| scop^ Lru:lud0 probes. scMecnatbs. operaiors maiuial and 3 year (2 yrs for Eterioo scopes) world M^« osdlbscopes. 1 1 0x Scopo Probes: P> 1 65 MHz (19.95* P-2 1 DO MHz $26.95 B + K TEST EQUtPMENT All Models Available Coll for special price Digital Capacitance Meter CM-1550B $58.95 1p! ^0.000ufd .5% bssft KCf Zero control wf Cas« Digital LCfl Meter LC-1B01 S125 Moasurod: CoilJ lgH-200H dpi .1pl-20&ut Bigi'DfSpby Muili meter with Copocltance & Transistor Teslef $55 CM-1500B Read^ Vo^ts. 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STANDARD AMATEUR RADIOS Now available - Ihe worlds finest amateur radios. Unsumassed quality and leatures make STANDARD I he worlds most poputar line of amateur radios. Mini Petuxe NTs: C16BA2metef Q46BA 450MHz Twin Band HTs C22dA 2M/22DMHZ C528A 2M/440MKZ Twin Band Mobile C560SOA 2M/440MHZ CALL CALL CALL We also tiave many accessories tor theso radios and most heatti radios. CalMor details. WE WILL NOT BE UNDERSOLOI S Stijppmg: 45 Slotes 5% i Mirr SIO Mox) Shipping Res,. 7.5% Tox FAX: 708^520^0085 C & S SALES INC. t2-l5 RcistutKKt, Deerritld, tL 60OI5 iSOC>i2y3-77II <70S>54l-n7IO 15 Day Money Bock Guarantee 2 Year Warranty ^^^^ svacc: to c^^f^^t WRITE FOR FREE CATALOG 89 CmCUE 109 ON FREE INFOAIAATION CARD COMPUTER CONNECTIONS Industry evolution JEFF HOLTZMAN IBM dominates the news this month. Since fast time. Big Blue signed an historic accord with Intel, formed a trade group with Ap- ple and Motorola, and commenced internal restructuring that, if sue- cessfuL could point the way to sur- vival for several major U.S. industries Cnot just the computer in- dustry). If, however, that restructur- ing IS unsuccessful, it may be a harbinger of how the computer in- dustry will follow the automotive and steel industries down the tubes. IBM + Intel With the new- found friendship among IBM, Apple, and Motorola reached last summer you nr^ay have wondered about IBM's commitment to the Intel platform. Well, wonder no longer IBM and Intel signed a ten-year agreement under which they will collaborate on the design of new 80x86 IC's. About the signifi- cance of this deal. Intel's CEO An- drew Grove has said. "This is probably the biggest deal I have signed in my professional career." The two companies will establish a 100-person development center composed of scientists and engi- neers from both IBM and Intel Intel will contribute CPU designs: IBM will contribute systems -!eve) exper- tise and semiconductor manufactur- ing technology. (It s not well known ^ that IBM is one of the largest semi- g conductor manufacturers m the ^ world.) It w»ll take about two years to ^ produce results, including highly in* ^ legrated modules that incorporate 8 CPU. cache memory, memory man- I agement, bus interface logic, disk 1 conlrolfer. and graphics. The com- panies will develop these products -6 jointly; IBM will have a four-month lead in commercializing systems, after which time Intel can sell IC's on the open market. IBM has had the 90 right to build and enhance its own 386 CPUs since 1987. (An en- hanced CPU would include the 386SLC. the *"weird" CPU men- tioned here last time as part of IBM's UIti media PC.) However the new agreement precludes IBM from enhancing future 486-based CPU s. IBM s four-month lead- as well the changing business climate, has competitors like Compaq deeply worried. For years Compaq was one of Intel's most Icsyal customers Re- cently however the company has been warming up to AMD. which is expected to release a line of 486 clones sonnetime in 1992. Because AMD and Chips & Technologies have already successfully cloned the 386, Intel's marketing effort is focusmg more and more on the 486 line. AMD is achieving great suc- cess with its 386 line by exceeding its own sales forecasts of 386 clones by 400% through t991, for a total of about 20% of the 386 mar- ket. Intel also suffered a setback m the math coprocessor clone depart- ment: a judge in Texas has ailed that Cyrix may continue selling tts FasMath clones until a combined antitrust/patent infringement case reaches trial in late summer 1992. The good thing about all of this ts that Intel is not content with trying to protect its prior accomplishments, and in the process leaving the fate of the company Cnot to mention the industry that depends on x86 chips) up to its lawyers. Rather, it is morving ahead and designing innovative new products, thereby staying a step or two ahead of the doners. If the soft- ware industry followed this kind of model, we'd probably be much fur- ther along in the move toward graphical operating environments, IBM Apple ^ Motorola Those three companies are form* ing a trade association. Power- Open, dedicated to defining and promulgating software standard; for the RISC-based PowerPC archi tecture announced as part of las summers historic Apple/IBM ac cord. These standards involve defi ning the instruction set of tht PowerPC, a cross platform binar compatibility layer called the Ap plication Binary Interface CABl). am high-level programming interfaces The intent of these technologies i to provide a "universal" softwan envin^nment that will support future Macintosh and OSF/Motif appticc tions. as well as current Mac an- DOS applications (through emt tators). and AIX applications. CAIX i IBM's version of UNIX,) IBM an Apple are also talking about mere mg AIX and AU/X (Apple's versior over the next few years . With both Motorola and Intel in it hip pocket, IBM now stands poise to build an incredible machine, on that provides hardware-level sup port for the major operating syj tems of the 90 s: Macintosh, DOS Windows, and standards-base UNIX, 1993 will be an interestin year for PC System architecturei IBM restructuring IBM s restructunng may seem t be one of those ho-hum things th^ the company seems to go thrBug with increasing frequency in recer years. Don't t>eton it. IBM is in dee trouble. Not only IBM the compan but America's whole way of doir business. If IBM fails, we're all goir to be liable to significantly increase risk of domination by unfriendly fc eign vendors. There are people wh believe that this risk represents greater threat to our society an way of life than the political and mi tary risks usually harped on by th press, in Washington, and in oi state and local governments. Yc may not like IBM, but you*d bett< hope that it finds a way of respon* ng competitrvely lo the changes go- ng on in the world at large. The most visible but probably east strategicalJy important change ^^s the *^^educt^o^" of 20,000 jobs, 3t a one-lime cost of $3 billion, viore significant is the decision lo Bduce control over and grant in- creased autonomy to IBM s major divisions (mainframe, AS/400. lS/6000. PC's, core technologies, jtcJ. Under this new scheme, each iivision will exert greater control ys/er its fate, thereby allowing faster espouse time to rapidly changing narket conditions. In recent years. BM has suffered increasingly at the lands of smaller, more efficient nore integrated companies that :ould detect and rapidly respond to :ome market need, be it portable ^C's. engineering workstations, op- crating systems, or what have you. 3M suffered again and again be- :ause its bureaucracy got in the way )f responding to rapidly charigmg customer needs. In addition the ompany suffered from internal Jtckenng over product features and narketing In some cases, com- ietilors were able to commercialize iroducts before IBM could get out >f the planning stage. Meanwhile, he company's market share and redibility dropped on a yearly basis » chieving cnsts level in the early part if this decade. It s stifl too early to tell whether hese changes will provide the eeded benefits. There are plenty of keptics who say that A) the hanges do not go far enough, and i) even if they did. they cannot be nplemented in time. I hope the nay-sayers are wrong, he U.S. needs new modeb of oing business on a very large cale; IBM is poised to lead the way. IBM fails H who. if anyone, will be ble to show us how? lews bits Intel has leaked more details of ie 586, which will contain 256K of ache memory, a 64- bit data bus. nd a 36 bit address bus. It will run t speeds of 33-, 50-. 66-. and 100- 4Hz, and it will execute common istructions at a rate of two per lock cycle. By contrast, the 486 jns at a nfiaximum of one instruc- on per cycle, and the 386 at two Phoenix Technologies (of clone BIOS fame) has created a reference design for a nev/ class of device called a Companion PC. It will have a 6" X 10" footprint, a full keyboard. CGA graphics, long battery life, and software support (including DOS 5.0 m ROM) by Microsoft and Lotus. Sony meanwhile, has shown 3 hand-held pen-based input device, currently sold only in Japan for about $500. The PTC-SOO mea- sures about 2.5" X 6" X 1". and has a large LCD used for both input and output. The device performs sched- PRODUCTS AND VENDORS • Adobe Type Manager (S99), Adobe Systems Incorporated. 1585 Charleston Road, RO. Box 7900, Mountain View, CA 94039-7900. (800) 833-6687. (415) 961-4400. CIRCLE 41 ON FREE INFORMATION CARD • CrossTalk for Windows 1.2 (SI 95). DCA. 100O Aldennan Drive. Alpharetta, GA 30201-4199, (404) 442-4000. CIRCLE 42 ON FREE INFORMATION CARD • Designer 3.1 {S695). Micrografx, 1301 Arapaho. Rrchardson, TX 75081. (800) 733-3729, (214) 234*1769. QRCLE 43 ON FREE INFORMATION CAIID • Word for Windows 2,0 ($495), Microsoft Corp., One Microsoft Way. Redmond, WA 98052-6399. (206) 802-8080, CIRCLE 44 OK FREE INFORMATION CARD # Muftfnredia Programmers Refer- ence (S27,95), Multimedia Author- irrg and Tools Guide (S24.95), and Multimedia Programmers Refer- ence (S22.95). Microsoft Corp, ORCLE 4S ON FREE INFORMATION CARD • The Programmer's PC Sour- cebook ($39.95), Microsoft Corp, CIRCLE 46 ON FREE INFORMATION CARD • Lantaslic 4.0 ($99/S50 upgrade), Lantastic for Windows {S299K Ar- tisoft, Artisoft Plaza, 575 River Road, Tucson. AZ 85704. (602) 293-6363. DRCLE 47 ON FREE INFORMATION CARD uling. database, and note-taking functions, appears to have a cal- culator-style keypad, and communi- cates with a docking station via infrared link. Apple is known to be vrorking with Sony on some sort of miniaturized hand-held device, pos- sibly CD-ROM based. Product watch About twice a year or so I feel obligated to report on the software 1 m currently using. Things have ac- tually settled down in the past year and a half or so: I haven't switched a single major applicetton in that time. Best Windows word processor: still Word for Windows, recently up- graded to version 2 0. It is unques- tionably the most powerful and best integrated product for the Wmdows environment. Its desktop publishing features are still weaker than I'd like, but otherwise, I have few com- plaints, WW2 now has builtHn draw- ing and charting packages, and a much more logical user interface. Clf you install all the extras, you 11 need about 1 5MB of dtsk space. I know it hurts, but this is a trend that seems likely to continued The program lists for S495, but just about anyone can obtain an "upgrade" for $129 by calling C800) 323-3577. Ext. W87. Drawing/illustration package: De- signer which boasts much in- creased speed compared with the previous version, text along a curve, batch printing, and more. Best Win- dows utility: Adobe Type Manager (ATM), version 2.0. Print any font on any Windows-supported printer, and see it accurately displayed on- screen. Best telecommunications program: Crosstalk for Windows, version 1.2, This version adds sup- port for networked modems, icon- based session launching, dialing queues, and numerous small enhan- cements. I regularly transfer huge files in the background at 9600 bps with total reliability. Best small-office network; LAN- tastic 4,0 The fatest version adds speed and support for operating both servers and workstations un- der the 386-enhanced mode of Win- dows 3.0 (see Fig. 0. A new utility allows a dedicated server to devote all its resources to the network, greatly improving performance. LANtastic for Windows provides full IE Copyright 19S1 flrtispft loc. Resource hdnc => Local Fdth/Deuice Yoii can also set up printer and nail resources. These resources are sjiecial and require an at sign "e'' at the beginning the nanc. dftniHIX Js an ejcaitpic of a printer resource, uhilc GRAIL is aluai/s the nanc of the nail pcsoitrcc* Printer resources can refer to the seruer's parallel or serial ports. /Hone/PqUp-Go up, i/End/FqDn-do 6am t 3-2oofli tsc-Exit he! FtG. 1<^LANTASTIC 4.0 provides greater speed and security, and full support for Windows 3,0. A separate Windows utilily allows full access to all r>etwork and manage- ment functions. Windows- based versions of the NET and NET — MGR programs which allow you to log on and off the network, administer network re* sources, etc. If you're in the mar* ket for a fully Windows-integrated. loW'COsL DOS-based local area network, there s really no other choice. Book nook If you're interested in getting started with multimedia develop- ment under Windows, but don't have a clue about how to get start- ed, check out these three volumes; Multf media Programmer's Refer- ence. Multimedta Authoring and Too!s Guide, and Muttimedia Pro- grammars Reference. All three an published by Microsoft: they an also included as part of Microsoft" Multimedia Development Kit. Th* Reference details Windows syster calls, file formats^ and data struc tures: the Workbook describe sample applications: the Guid^ shows how to build multimedia ap plications. Another impressive Mi crosoft volume is the seconi edition of the The Programmers Pi Sourcebook, which contains abou 800 pages of tables covering jus about everything you could possibl want to know about the PC arch tecture, both hardware and soft ware. Want to know how to cross wire a 9- to 25-pin RS-232 adapter No problem. How about the struc ture of the boot sector of a flopp disk? Easy. Maybe a listings of a BIOS, DOS. and Windows functio calls? Simple. Mayb 8088/86/286/386/486 instructio sets? Piece of cake. Not to mer tion: physical sizes and shapes c XT/AT/EISA/MicroChannet expar sion cards, expansion bus pinouts IC pinouts, etc.. etc., etc. If you ow just one technical reference on th PC architecture, this should be it. Next times An in-depth look £ CompuAdd s Multimedia upgrad components. R- MESSACINC SYSTEM con tinu ed fro m page 64 whenever ag or a7. or both, are low at the time ce goes low. The ISD 1016s storage array is ar- ranged in 160 segments of OA sceond each. The segments are numbered 0-9Fh, They may be accessed randomly, howcv^er play and record operations will access them sequentially begin- ning with the address supplied by DIP switch S4 at ao-a7, until an HOM marker is encountered, or the operation is terminated by bringing CE high. lb determine the address to use to select a particular mes- sage, or to record a message at a specific point in memory, we will use a simple example. Suppose we want to hear a message we know starts at the 5-seeond point in memor^^. Each memor\^ segment is O,l*second long, so our message starts at segment 50 (5/0.1 = 50), Now we simply convert the decimal segment number into hex (50 decimal = 32 hex). Thus S4 switches 1^ must be a binary "3*' and switches 5--8 must be a binary "2/* so switches 2, 5, and 6 would be open (bits 1, 4, and 5 highl. Configuratioii mode If address bits 6 and 7 are both high (S4 switches 7 and 8 both open) at the time ce goes low, the ISD 1016 enters the "Configuration Mode," in which address bits Ao-Af) (S4 switches 1—6) take on a different mean- ing, in this mode, those address bits no longer specify ad- dresses. Instead, they select among the various options available as shown in Table 2. To illustrate the use of Config- uration mode, lets assume w recorded a message ttsing th instructions given earlier, an< we would like to have it repes continuously (Make sure th message is less than 16 second long so the '*overfiow" conditio won't disable the chip after th first replay. Also, the Addressin mode and Configuration mod are mutually exclusive, so yo can have only one message i Configuration mode.) To pla the message back continuousl we want to be in the Configuri tion mode: A3, ai*, and at hig (open), and the rest of the ac dress switches closed. Now si Power dowrVUp to the "up" pos tion, and set Disable/Enable I the "enable" position. The mes sage that your recorded will no^ repeat contintiously until cb i set to the "disable" position (o of course, until your battery power gets used up). BUYER'S MART FOR SALE ESTRICTEDiechnical informalion: Eleclronic jEveiiiance, schamatics. locksmithing, covert :ience5. hacking, oic. Huge selection. Free -ocf>ures. MENTOR-Z* Drmor 1549. Asbury irk. NJ 07712. FIBER optics kits. ExperimentefS S24.50. Daialink w/PCB S36 25, HILL ELECTRONICS, Box 47103. PhQQnix. AZ 65068-71 03. CABLEBOX: Fully acUvale your Zenith ST5612. with no parts! Ulustraiod instruction manual S9.99. JIM CHASE, Box 148332, Nashville. TN 37214. CLASSIFIED AD ORDER FORM to run Yxur own cUtt)1i*d ad, put orw word on uch of the lin«a bitow snd i*nd thim form «long rcut eh*ek fa: Radio-Electron ICS ClassiOed Ads» 500-B Bi-County Boulevard, Farrrvingcfale. 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Card Nunit>er Expiration Dafe PleasflPrmi Namo Signalurcr IF you USE A BOX NUMBER YOU MUST INCLUDE YOUR PERMANENT ADDRESS AND PHO^E NUMBER FOR OUR FIL£S, AOS 5U6MrmO WTTWOUT THIS INFORM ATIOH WLL NOT BE ACCEPTED, CLASSIFIED COMMERCIAL RATE: (tor fums Of jndJViriua^s otiefinq commefc al prtxJydS or servaces) S3.t0 p^f wofd pf^pa»d {no charge aid NON-COMMERClAi RATE: (for indiVFduiils who wnrnt to buy or sell a personal el em) S2.50 per ^xyrti proparti no minimum ONLY FIRST WORD AND NAME Gel m bofd caps oE no extra charge. AddittcntiE bo^cJ Nicij (not ^T^-nilabie as ali caps) SS< per word additional, Bncire ad m boldlace, $3 70 per word. TINT SCREEN 8EHIND ENTIRE AD: S3.e5 per word. TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD: S4 50 per word EXPANDED TYPE AD: S4, 70 per word prepakl. Entir^ad in hofdface. S5 60 per woid TINT $CRE£N BEHIND ENTIRE EXPANDED TYPE AD: S5 90 per word. TtMT SCREEN BEHIND ENTIRE EXPANDED TYPt AD PLUS ALL BOLD FACE AD: Se SO per wford, DISPLAY ADS: T 2' *' S-ilOOO 2 ■ 2' ■ — SflSOOO, 3 ■ 2V*' — Si 230 00 General Information: Frequency rates and pfopaymenl discciynts are available ALL COPY SUBJECT TO PUBLISHERS APPROVAL. ADVERTISEMENTS USING RO. BOX ADDRESS WtLL NOT BE ACCEPTED UNTIL ADVERTISER SUPPLIES PUBLISHER WITH PERMANENT ADDRESS AMD PHONE NUMBER. Copy to be in our nands on the 5th of ine third monih pfeOMBng the d^ of Uw issue El 0 . Aug i^sue copy must be feceiwd by May 5th) When normal dosing (Me 1w on Salufdiq^ Sunday or Holiday, i^ue cioses on prece<$rr>g woriiing diay. Send tor me dass«1ied brochute. Circle Nun^Mr 43 on the Free Inforrnation Card. CABLE TV conveners: Jerroid, Oak, Scientific Allantia Zenilh & many others. "New MTS'^ stereo add-on: rrnrlo & volume Ideal for 400 and 450 Ownersf 1 (BOO) 826-7623, Amex, Visa, IVI.C ac- cepiod. B $L B INC., 4030 Beau-O-Ru© Drm, Eagan. MN 551 2g. TUBES» now, up 10 90% off, SASE, KIRBY^ 298 West Carmel Drive. CarmeL IN 46032. T,V, noich fillers, phone rejcordlng equipment, bro- chuf5» SI -00 MICRO THific. Box 63 6025. Mar- gate, FL 33063, (305) 752-920a WmELESS CABLE flECElVERS 1.9 TO 2.7 GHi mooia, u. tsvr Mjamatm CIRCUIT Ooards — Complete printed circuit lab- ficatron from single SidecJ 10 production mylli- layors Twenty -four hour turnaround available. CfRCUIT CENTER, PO Box 128, Addison, 11 60101 1708) 543-0671. JERROLD, Tocorri and Zenilh 'HeM" chips. Fully activates unll. S50.0D. Cable de- scramblers from $40,00. Orders 1 (flQD> 452-7090. Ififormatlort (310) 367-0061. TEST equipment pre-owraed now at affordable pfjces Signal generatOTS from S50 00, OS- oiEoscopos from i50 00, ottierequFpment, )r>diJd- ing manuals available. Send S2.00 U S, lor catdloQ. refunded on 1st order. J.B. ELEC* TRONICS^ 3446 Dempster, Skgkie, IL 60076. (706)982-1973, DESCBAMBLERS: Oak Sigma. Varisync, Hamlin, Scientific Atlanta. Jenold. Pioneer. SyJ- vania. Caiaiog S5 00 morreyorder {credited first OfCterL seivtce manuals, sdnematics, SURPLUS ELECTRONICS, PO Box 10009. Colorado Bpfim* 00 80932. CB RADIO OWNERS! We specialize in a wide variety of technical information, parts and services for CB radios 10-Meter and FM conversion kits, repair books, plans, high-pertormance accessories. Thousands of satisfied customers since 1976! Catalog S2 CBC INTERKATIONAL P.O. BOX 31500RE. PHOENIX. AZ 85046 SPEAKER fepair. All makes ~ models. StefBO & professional Kits available. Refoamsng $18. 00, ATLANTA AUDIO LABS, 1 f&OO) 568-6971 ENGINEERING software aod hardware, PC/ MSDOS. Circuit design afid drawing, PCB layout, FFT analysis. Mathematics, Circuit analysis, etc. Data acquisition, generation. 1/0 RGB's, etc. Call or write for free catalog, (614) 4gi'0832. BSOFT SOFTWARE, INC., 444 Colton Rd., Colymbus, OH 43207, OSCILLOSCOPE 50 MHz, Hewlett-Packard, sol- id state calibratsd, manual $200.00 t [600} 835-6335 X-t59. CABLE TV EqulpmenL Most type available. Speda): Oak M35B S39.95. No catalog. COO or- ders only 1 (800) B22-9955. (£3 N jD 9- D O 93 DESCRAMBLER5 THE ELECTRONIC GOLDMINE All major brands carried ♦jerrold, ♦tocom, *zen1th *ge:neral instruments ♦scientific atlanta, ♦oak ♦hamlin, *eagle, *pioneer 7ih Year in bus mess. Thank You Member a f Omaha Chamber of Commerce 1 Year wananty on new oqyipmeni 30 Day money back guarantee Orders shipped from stock wiihin 24 hours CALL TODAY FOR A FREE CATALOG 1-800-624-1150 C.O.D. ■S, ^ 8T5S0.72DdSL C6362 $tO« «itmcLE amn kit M'^ ^ 3 LTrtn t •Of C6374 [NSANmr ALARM JUT C36447 PStC CALLER KIT C45Ge $4*" SIGN KTT DiTMAKKD DnTCTOn Ci-^ Mkrti r>-. 1^ r, i,-^ J ■ n-lri-J *- — - " - CS441 S5," CmCLE 53 OH FftEE INFORM AHOK CABO Aiiti w «ni uonir OM CIRCLE 177 OK FREE IHFORMATIOM CARD Quality Microwave TV Antennas M — t WMIELISS OiU - ftS - ■ ftnutwr Vi PHIILIPS-TECK EtECTRONfCS Pybp' P.O. Bdi 6533 • Scolt^dale, kl 85252 UrETIME 1 6^^} 947-7700 «U Credii ill phonfl Dfitofif Si i O ■D fa 94 ELECTRONIC supermarket surplus prices! Trarislormer specials, railroaders, builders, ongi- rteers. oxperimenlers, LSASE, FERTIK'S, 5400 Ella, Phila,. PA 1912Q. OUR morvthly p^cluie flyer Bsts quahly surplus parts al lew prices Send today for youfs. STAR- TROHtCS, Box 6B3. McMinrwilte. OR 97t gS. PHOTOFACT folders under #t4O0 S5 00 Others $7.00. Posi;^Ki. UOEB. 414 Diestnui l-ane. East Meadow. NY H554, (5iej 4©l-i3e0. FREE CATALOG FAMOUS ^TIRESTIK" BRAND CB ANTENHAS AHO ACCESSORIES. QUALITY PRODUCTS FOR THE SERIOUS CB fif. SINCE 1962 FIRESTIK ANTENNA COMPANY 2614 EAST ADAMS PHOENIX, ARIZONA 85034 REMOTE telephone recorder, S379.00, wilb roorn moniror, S479.O0. Room monitor S175.00. Room & tolophone S275 00. Catalog, $3 00, LISTEN ELECTRONICS. 603 Elgin. Muskogee. OK 74401 (918) 683-9589. f*m *i* 5:ri RNALLY — A cross part database program for industry standard pari number*, Crosses In- dustry siandard part numtjers to two man- ufacturers of replacement components. Gives the user technical information and allows the user to create a database of electronic compo- nents. (3) — 3 \'2 disks. IBM PC compatible. Send S38.00 to CPS SOFTWARE^ PO Box 28. Blackwel l. OK 74631, IMPOSSI BLE cable systems. New user program- mable untis authorize any of all teniuros of Pi- oneer or Jerrold descrambiers. TAKE CONTROL, t (800)968-4041. ^ 80CS2' Basic microcontmllcr t>oard. Basic inter- preter 32K RAM, 16K Epfom, E prom programmer, RS232, expansion connector Bare board with manual schematics S22 95 80C52- Basic micro- processor chip S25 95 Assembled mc lested S124.95. PROLOCIC DESIGNS, PO Box 19026, eallimore, MD 21204. Advanced solld-stote LASER SUB WOOFER desiqn software Desjgn: porte* sealed, JSobar;iL er^dosures. Calculates optmu to* Size, graphs porfomiance any subwoofer IB 5.25 disk: S19.95, SUB-ENGtNEERlNG. Be 1236-R. CorvalUs. OR 97330 m TV AKtJ SAraUTE DISCIIAIIBUMC ALL NiW 1 99Z lOtHa N Ail NIW : :HJHa tagL aiQiCs ybirrr 01%, EOtf^ Di ' :ii m (te U0>ft(M fiS % M 1 : 9i : - 5.-1 i VMm tfimm S tin » VPS Meiu DESCRAMBLERS. M^35-B $19.00, RTC-5 $69.00. Z-Tac St 99.00, 5503 S199.00. SAS- S59.00. FTB S59 00. al! brands m stock. MOUN HOOD ELECTRONICS, <206) 260-0107, CABLE boxes. All brands and models, FutI wa raniy, same day shipping, examples RTC-5 5503'VIP turn on chip $29.00, M*35-B ' (it S14.00 ea. S.A.g, 1 (BOO) 622-3799, CABLE test ctllps, S-A B550. S-A 8600 — 31 311, 320. 321 (spec(ty) — S33.9S. S-A e580'3: — S69.95. Tocom 5503 07 VIP — S33.95. TEL! CODE. PO Box 6426-RE. Yuma. AZ 85366-642 CABLE TV DESCRAMBLER LIQUIDATIQ FREE CATALOG! HamJln Combot S44. Oak MISS S60 (min. 5}, e WEST COAST ELECTRONIC For Informalioni 818-709-175B Catalogs & Orders: 800-628-9656 LAND General mobile radios. CB's, scanner radar detectors, auto alarms, marine (ran celvers catalog $2.00. RAYS. Box 14S62RE. I Worth, TX 76117-0662. TUBN-ON kits for Staicom VII, S40.00: Starco VI, S30.00, Siafcom OPBB, $50 00; Pione< S75.O0: Tocom VtP 5503 5507. S25.0O, S . $30,00; Zenith. S25.00; Call RE- ENGlNEEi IWG, (617) 770-3830. TUBES: "Oldest, ' ^latest." Parts and schematic SASE for iists. STEINMETZ, 7519 Maplewo< Ave.. R.E.. Hammond. IN 46324, PLANS AND KITS FASCINATING electronic devices! Dazor Laser s! FM AM pfione transmi Iters! Detector Kits assembled? Calalog S2.00. QUANTUM Rl SEARCH. 166^15-113 Avenue. Edmonton, A! T5M 2X2. H 0 B B Y b road casii ng HAM C B/su rve i llanct transmitters, ampltfiers. cable TV. science, buc othef great projects' Catalog St. 00, PANAX! BOK 130-F3, Paradise, CA 95967 PROJECTION TV Convert your TV to pro|ecT 7-?ooi picture . Easy? Besutts comparatDte $2,500 OC prq^ors Plans and lens $29.95 Protessionaf systems ^i-ajtabo I fusJraied cal log rrM.„ MACROCOMA, 1SGG Majn Slrei Wisfiinqum Crossing. Rft 18977... Creditcaid t ders 24hrs. 1 (800) 955*3979. tmm 10% on (3 two or mcfe! $175,00 b«im (i^m. fl Jt |0 nit pnwmr POLARIS Industries Wtr,,, , 1(4) 'HUE- rUHl U CtS r^u Tm^I t^r* lliif ITt^lf^ iMm 1-800-222-5620 REMOTE CONTROL KEYCHAIl find +S vdc RF rocsiv FuWf ««»£mblcd including plAi to tiuild ycur own Mt> alar Otieniity discouriia *v»ilab iS^nA ntr Chock. V! a a o r M ^d^.)^0 Addsauhippii VISIT ECT INC. BQt 14 150, ffemofiL (510) 651-1425 Fax (510) 651-84; PCB aod schematic CAD. S195.00 IBM EGA CGA Muftifay^r rubborband. auiovia. MC dn i. iiisor, do* malrjjt, ploner, library. Gerber. AUTOSCEKE. 10565 Bluebird Sr., Minneapolis, MN 55433. (612) 757-8564 free demo disk. VIDHOClPHER II scanner cab Ee sate'Eitomodi- ficat ons tX50^s Catalog — S3 00 TELECOOE, PO Box 6^26-R£. Yyma. AZ 85366-6426 DESCRAMBLEfl kits. Complete cable kil $44. 9S. Compleie saieEliie kit S49,95. Add S5 00 shipping Fnse brochure. No New YoiK sales. SUMMIT RE, Box 489. Bronx. NY 10465. SURVOLLAWCE transmitter kits tune from 65 to 305 MHz Mains powered duple k. telephone, room, combination to'ophono rcxim. Catalog wilh Popular CommunicatEofts, Popular Elec- tronics and Radio- Electronics book reviews oi "Electronic Eavesdropping Equipment De* sign/" 52.00 SHEFFIELD ELECTRONICS, 7223 Stony IsEand Ave.. CNcsgo. IL 60^9-2B06. CREDIT card encocing. standard oicpfaine§m to SOU pto dioct» 1051 wnh audbw conUm^. S cutT«n] rangn to IDA. Buitt-tnbafiwymiand LFE ti»i fE>f Nl^N and PU? t!^a?tisstoft, To*l l&ads. in*trijci«)nt and C3.'7yir.g caa* iiXiicSed. #RD-390-l40 Infrared Detector Pen The wof first handliald. Banery pottwvS, IntraRedDeiactorpen. Insiaiuhr rocoffmiei r^rafod Ighi rrotn Toiavbon. VCR. am nwno ^amc^ comro^. VCR tape slop d^ia. aiiirTn perimaier d«t«aoi9, and thouundt of t^m IR contFoied product. Matr^fw^aafimW* DJ W«C i C»c( Wig^ lBniynHlnwefiMBWtag. Sim liind optmfini maliH I tatf 10 fittcti n i9cntsw on cfQNKl VCR tap9 nwd'ijrtw*- A i^ffy^na caM fo V"Mia and uantport your S-LR-D. A avaSbi« lor Saj$, order 93aQ-m . #RD>39i^200 $34| IC Protector Kit ConwivfS ss into pl»». Standard fflptapfrffi^T p^sstc box 'or cassettes. Black basfi' wtih dear lid in ih« U.SJL f^^ #RD-260-29S 95|a;:h #RD-Z00-O«0 ♦Each Pioneer 4-1/2" Full Range This veiy popular woofer Is portocJ tof mjTJ( I ng boc^ishelf speak o r s or for car f^to^eo instaJSations. Response: 7EM5 ' KHz. fl- 70N2, SDwansRWS.SS WBQtn^^ SPl.-90d5 tWHM. to 02. mtgmt. e o^m Frrpedance. Poneof iAllECS&O^. Wol*o^M: 2 bs. #HD*29(WH0 59fach 18** Eminence Woofer Bau rat'At fwcfer wdi rbbad papv qpm and irs^ed dbdi accord^ •urnxmd^ Giiart IQO oz. magn«t. 20Q iimRM$.3C»winamxK. T.2 tiy«r %oice ood. S ohm impwsafice (7.5 Q^JTl dcR) Frttqusne^ msporss: Z7-3.000 Hi, fs- Zi.ot Hz #RD*290-200 acJi S99^ 12** Pioneer Subwoofer \T f ijpflir duty, diuia] voks coQ MibwooTor. 30 01. rT:^neK, r vo3ce cojL 100 warts RMS. 14S wans majt. 25 rosongnr fiToqucncy. eoh-m jrrp^anoe £4 andeohmcorrpaiiblsK Sensillvl/: 94 dB lW/tM Ro4pon$H; 2^1,&00 H2. PlOflMr iA30GLf3Cr-55D, #RD-290-145 $39^, 30 da/ monay back guaiiimoo ' S?0,00 minimum order * We accepi MaslsrcardT. V^s^^, Discovor, and C O. D, Ofdftrs, * snipping chargo - UPS Chan rate » Sl .OO safQfl) ■ Hours 8:30 am ■ 7.tX)pfnEST, lond^.iy ■ Fnda/ ' 9;Do am - 3 00 pm Saturday, UaH ofdor £4 hour i hipping jS3.50 minimum chargfl cu$(oni9rs, pl»aM CAil (or thippirig esiimato on ortfon OK^edinf ' ._'__.! wfld £5.00 U,3. luftd* ^ cttaJeg pwtggb * CALL TOLL FREE S^^^ 1-800-338-0531 FREE CATALOG 9 m 3 3 95 CIRCLE 56 ON FREE INFQI^IIATION CAflD CaunmoiM Survive * DlMcotmt Pfic&t * F*9t Sh;pplr}g ALL ELECTROniCS p. 0. Box 567 ' Van Nuys, OA 91408 Electroluminescent BACKLIGHTS At Iffis^l A bw coel fl1eCTfiOluiTine$cen! glow strp and invert&r. Th«£a bfand-n^ unris wsfa d«&ign>ed to back- light smaU ICO TVs mada by the Citizen Watch conipany. Jh» ifivwter dfCuit chafvgs* 3 or 6 Vdc lo ajpJOJtimalflly 100 Vac, lha voltage requj/ed to light the gtowslrip. LumifW6C»f^( aurifaoe afoa ifi 1,7" X The sthp is a sa^n cator in hs oti stale, and gSows whiste when energized. Th# dicuit boartJ 1& 2.r X 1 V Glow Btrp and drculiry can be renrtovod oA^ily from pkubc hfli^sing. IdeoJ lor spacbJ lighting etfecfS and baddighiing. Two models avai tabkj; Citizen* 9 1 TA cperales on 3 Vcfo C ATi Si U ^ l Cit^«rwt 92T A opciratos on 3S Wc C ATJT B LU-tl QUANTtTY AVAILABLE l0fOfS32.00 • 100fofS2?5.00 Special Deal 12 VDC COOLING FANS T0VOFaft# TFDeOlSnXAL 12 vex;, 0.1 1 a cooling fan. 3J75* square X 0.92' thick. 7 blad* irrpeHor. 11 ' long pigtail leads. CAT«CF-124 10lor»50.00 SUPER SMALL Surface Mount Green LEO Surfaoe mount LEO chip, JC^X when oflr green when lit. ^^^3* Very tiny ■ whole unil ia 0,1 1 5" X 0.055" X 0.05" [hick. 1 mna {0.041 dlamoi^r. Gold^p^ted moufiting aur1ace« lor a iperlor conduct IvHy. CAT# SMLED^2 lOOfOftie.OO lOOO for $140.00 Pushbutton SMK Manirfaduflrtg 0.47* sqitare btack pushburtoa SPST fiomruiay open. 4 p^. pms lor mounting. IdeaJ lor km cun«nt swQChIng applications, CAT« P8-2S 1 00 fOfi 15.00 PHOTORESISTOR 1 K ohmfi bright Bght.l&K Ohms dark. 0,1 aa" d ia, X ,Oani Ig h. 0. 1 S" long l*adfi . CATi PRE*7 lOOfOf S45,00 1000 for iiOOOO TOLL FREE ORDER LINES 1-800''826'5432 fofttii46 contintmat U.S. A, S3. 50 pif otd^r. AM Qth*n inducing AJ<,Ht,PRof Canada msj^pAy fuff shippinQ. M Qfld^f* dttvAftd in CALFORNiA miat Vv^udv 9t9t9 timitvd, NO CO O. Priaaa subjici to chAng^ w/out mikm. Catt or WritG For Our FREE 64 Pago Catalog {Outstda The U.S. A. Send $2.00 Paat»go) ALL ELECTRONICS CORP. P.O. Box 567 ' Van Nuys, CA * 91408 f ^ « % ^ PRESErsmWG * * * * CABLE TV DESCRAMBLERS ***** STARRING ***** JERROUI, HAMUPI, OAH AND OTKEff FAWOUS MAJVUFACTUfiE RS • FINEST WAfTRAN'TV p-RCX^RAM AVArLASLE • LOWEST RETAJL i WHOL ESALE PRUZEl IN U.i. • ORDERS SHIPPED FPaM STOCK W!THI^^ 24 HJ?S. • ALL MAJOR CREDrr CARDS .ACCEPTED FOR FRFr CATALDG ONLY 1-800-145^27 FOfl All mwomMAtiOH 1*619-709-9937^ PACIFIC CABLE CO., INC. 7325'/i Reseda Blvd., Dent. 211 2 Reseda. CA 91335 SATELLITE TV FREE catalog — Lowest prices worldwide. Satis- (action guarantee on everything sold — systems, upgrades, parts, ail major brands factory fresh and warraniiod. SKYVISION, 1012 Frontier, Fer- gus Falls, MH 56537. 1 {800) 334-64SS. Outside OS f2lB} 739-5231. SATELLITE TV — Do it yourself — systerris. Up- grades. Parts. Major brands discounted 40% — eO%. We ll beat everyone's price. L.J.H. INC., call Larry {609) 596-0656. VIDEOCIPHER II, descrambltng manual. Sche- matics, video, and audio. Explains DES, Eprorr, CloneMasler, 3Musketeer Pay-per-view (HBO, Cinemax. Showtime, Adult, elc.) S16.95, $2,00 poslage. Schomalics for Videocypher Pfus, $20.00, Schematics for Videocypher 032, Si 5. 00. Collection of software to copy and alter Eprom codes. S2S.0O. CABLETR0NIC5, Box 30502R, Boihesda, MD 20824. / ELECTECH / CABLE T.V. DESCRAMBLERS * All quality brand nanries • < All fully gyaranteed - All the time • Knowledgeable Sales Service Department FOR FREE CATALOG BOO-253-0099 EDUCATION & INSTRUCTION F.C.C. Commercial General Radiotelephone li- cense, Elecironics home study. Fast, inexpen- sive' Freo" details. COMMAND, D-176, Box 2824. San Frandsco. CA 94126. Be a TV/VCR Repair Specialist Now y04j can iraini at home >n 5pare tsmc fo^ a money- nnaking tare&f as a TV.VCK Repair Specialist No previous ejcperj- ence nccessafy Ho need to Qtjit yotir loEj or scnoal. tvery thing 3S ejfpldfned in e^sHo^EJi^t^^^^siand l3rtgLt3.ci& with plenty of draw- ings, diagrams and ptiotos. We stioAj ytju tnjw to troubEeshoat jnd lepair vidett-ca^sett^ fccorders and TV sets, how Jo handle house calls arjd shop repairs lof afmcsl any make of fetevtsion or VCR Tools are included with your course so you can get ■ rtands-on" practice as you follow your Eessons step by step Send lor free facts about I be excittrg opporC unities in TV.'VCft Repair and lind out how you can ^tart irakirtg money in this great career^ MAI^CuUPON TODAY_ ^ J«* . 925 Oak Street. Scranton, PA 10515 J Pi east ^end mt lull intormatidri and color bfochuie on bow E can I learn TV'VCR Repair at home m rtiy spare (irre. I understand I I here is no o ligation and no salesman wilt visil me. ^Age Name I /Address I City/Slala [^lione|__)_ _ Apt #_ -Zip ELECTRONIC enqineerinq. 6 volumes complele. 5109.95, No prior Knowledge required. Free bro* Ctlure. BANNER TECHNTCAL BOOKS, 1203 Grant Avenue, Rockford, IL 61103. VCR tapes by college instruclor covering elec- tronic topics. Send for free demo S3. 50 P&H O.CS., PQ 292. Fori Mill, SO 2971 S. NEW book. Ceiling Started in Nuclear Physics. Easy 10 follow with illustrative footnotes and ad- vanced practical procedures. S19.95, FARAK FAR AH, PO BOJc 2464, Sarnia, Ontario, NTT TTl Canada. CABLE TV DESCRAMBLERS ALL TYPES 800-582-1114 FREE CATALOG M.K. ELECTRONICS<79S8P\nesBM Suite 276 • Pembroke Pines, FL 33G24 BUSINESS OPPORTUNITIES YOUR own radio station! Licensed/unlicensed AM. Ffvl, TV. cable. Informalion Si .00. BROAD- CASTING> 80K 130-F3. Paradise, CA 95967, LET the government finance your small business. Grants' loans to $500,000, Free recorded mes- sag&: {707) 449-6600. {K$1). EASY work! Excellent pay I Assemble products at home. Call toll free T (800) 467-5566 Ext, 5192. MAKE S$S! Become an American electronics deateri Profit opportunities since 1965. Call SCOTT PRIiETT, 1 (SOO) 873-1373. HOME assembly work availabtel Guaranteed easy money! Free detailsl HOMEWORK-R» Box 520. Danville, NH 03819. MONEYMAKERSI Easy! One man CRT rebuild- ing machinery. $6,900,00 rebuilt. $15,900,00 new. CRT 1909 Louise. Crystalake. IL 60014, (815) 459-0666. Fax (815) 477-7013. c AiM.i: T\ i>i:s* liAMiti.Kks BEST BUYS BEST SERVICE BULLET PROOF TV TESTED WAMT TO BUY; TOCOM. SA S5eci,PPVT2l2 Cafl fa Vour Who£*l^* ML3iiJ,Vt*l&n (402)331-3228 8 0 0-835-2330 ElflcireriiCi™ 2730 S0.123rd Cl^US Omiti. NE 6HlAi WANTED INVENTIONS' new products Ideas wanted: call TLCI for free informalion inventors newsteller. t (600) 458-7200 24 hours day - USACanada, INVENTORS: We sub mi I ideas to industry Find out what we can do for you. 1 (600) 28840 E A. INVENTORS! Confused? Need help? Cai IMPAC for free information kit. USA' CANADA: 1 (SOOl 225-5800 (24 hours!). MASTERCARD AND VISA are now acceptec for payment of your advertising. Simply complele the form on the first page of thE Market Center and we will bill THIS IS AN EXPANDED TYPE AD. Notice how it stands out on this page. To get your ac set in this type style mark your cfassified ac order. "Expanded-type ad." and calculate your cost at S470 per word. CIRCLE 107 ON FREE tNFORMATlOM CARD CORI\ lECIRONICS LASER DIODES TOCK ■ MFG. WAVE- LENGTH OUTPUT POWER OPER. CUHR. OPER. VOLT. 25-99 TOSHI&A 3fnW 0S mA 2^V m.n 123.49 111.14 S920O TOSHIBA 670rifn JmW as mA 2JV <7.99 43.19 S92t>l TOSHIBA e70nni 5 mW BO mA ^4V 5B,99 56,99 51,29 S9211 TOSHIBA 5rnW 50 mA 2.3 V B^M 66.49 59.64 S3215 TOSHiaA E70nm 10 mW 4S mA 2.4 V 1 09.30 104.49 94.04 S32D0 NEC GTOnm 3mW 85 mA 2.2 V 5i.90 56,99 51,29 S022 SHARP 780nm SmW 65 mA 1.?S V 17.09 31053 PHILLIPS 10 mW m A 2.2 V 10 09 10 44 940 AO II PROGRAMMABLE ROBOTIC KIT Ttie pen mechanism eluded wrth |hc ro^Mjl allows it ID draw, in aodiuon lo drawing fUaigm imes^ il eati Also ^GOt- dimw out wordt «iid Mrt phrases. WO M comes with tZS X 4 bits RAM Mfd 2K ROM. afM3 is programirted directlfy via itie keypad anactiKi io it With its buiitt-inconm'clnr port. V/AO II is ready lo cornmunicato W(lh your computer With ttrc optovemcnt program, as wtW q$ savafig. and loading a profjfnm car bo porformEd by I ho Inlorface Nil. The kit Includos soltwarc, cstile, card, and inslructio^s The programming language is BASIC DEscfltpnon I V56 1 WAQ n Pfpg/ammaNe HobcHc Kif tO-24 25^ SINCE 1983 — YOUR i.C. SOURCE — AND MUCH MORE!' NO SHIPPING CHARGES ON PRE-PAID ORDERS!* NO CREDIT CARD SURCHARGE! SCHOOL P.O.'s WELCOME! PROTOBOARD DESIGN STATION ' Variable DC OMtpiil ■5 ' to -1 & voc (iv 05 amp. nppte * 5mV t Frequency ffert«t«tor trequeniCy range; 0.1 Hz lo 100 KHj m6 rnngos Oulput voltiigo: 0 to ± 10V (20 Vp^p) OLi[putirnpodtinc€:600 loxceptTTL) Output currtint: IDmA majt.. Short circuit protected output wsveTorn^: aine; ^uare, (riartde. TTL une wave: dJslorlion 3^ < 1 0 Hi to 100 KHi) TTL pu^: rue and fall Itmc 25ns drrw* aO TTL kMKJ> Square wave, rise artd tell timv ^ t .5 s I L^>Qtc todlcaiofv 3 LED's act-i»e ftigh, 14 vt>t1 (rtommali rhfesti^a np^ts p'oredcd to 1 30 vOlt» I Ocbeunced puthbutiont (pi^Htfi.! 2 pmh-tiulion dfwrased, opetxsomeiar ooipul iMMfi, cMtt Mfitli I normitfj^ open, 1 novrnsMy-closed otitpot. Eftcti output can sink up to 250 mA • Potenllomelen 1 - IK . 1 lOK . all ifMdfl ftvaiiabkf and uncofflm-tled ) BMC oofin«cton 2 connedors pm avaiiabi« artd uncomrmiTed shell GOnnectOd to ground t Speaker 0.25 W. B a • BresdbORrdlng arqii 2520 unco m nutted lie poinis ' Olchf^nslons 1 1.5" long s i 6" Aide X 5 5'' high k Input 3 vt\t& AG line i niKjt n 7 7 v. 60 • Mght rtbs • The tQta! design wonhslatkin - itKfudmg expanded instrurrmotation. IxBadbdifd and pow^ jmppiy • loedi tot anaiOiO, f^tftt and mkro- pf ocesKw cifcutti • ft io$pc probo cwtuiti • Ftmciion fefieniof «iili com ictyomty variatile tiot, 9quan&, mangte iH9ffi 1orm5. plus TTL pulSCS • Triple ppiMr supply otters taxed 5 VDC ^ppfy piyj 2 variable outputs - * 5 - 15 VDC and *5 * t5 VDC • S TTL eompalJ&4C LEO tndicalEffx. swilctics • Pulsers • PolDnliomcters • Audio Cxp((rfhvfrftlfltjOfli S^peakof • MuHfple fciilures in one compJele leial InsUumerit ftavos huntlreds of dollnrs riG^dod Eor in^lividLinl unit^ • UnJimited iifotlmo guaranty an bread- board lC>CkOt3 • fkxvi DC dulpul * S VDC 1 0 amp. f 5 ppfe - 5 mV • Varlatile bC outpul -5 - to '15 VDC ^ 0.5 amp, r 5mV 3m 68.39 34 m OESC«EPTT0M P6503 t-9 a* ?99 99 2S4 99 toe BENCH ASSEMBLY PRESS tafi»fl tool ^mrgnta ler fv* volume, tpttt tiwTiiinittOA ot *«nov» IOC cpnm clo f * on ttw ineruSHiiiTf wiltiuuE any |0oi) r«quii[Kl • AiOi jidoniii &cet)*iioritii Uslow * Ini^n - 10- W K Ct.W D X r H c^lumahhg pen ttm opcf BKng vona^Q a4 ?^-2 ^ @ 90-iUmA 4 thiigntd lawtf ponv^ jippiiC'iioiif such u 0^ uriffviir tile fijon-hefrnolie tta^iinmiMwi CAM •1 nsccrFn^iy fiittti^pied tor «)f aJ^fln- m$rti in an opucH iMd or wnt? Vf^am Rfto oxtaoJi * Iwi v)d a Mm ii>ode The iwn lytiem ccnmatai thv dti^vg^ qujiiil^ inJitrmciion l.milwJ Tn{' iir)i;'..Mi) II tifcular arid eiTPc0«i device designed fot a mau mnna Qi cipplicanons. OtM ■ d-arn « 5" DESCI^IF'TKIN 1-1 H* STOCK tt DESCfUFTlON %tHtA 3S« ^TOCK* OCSCRlPTiON COLUMAnNG LENS DUAL MODE LASER POINTER km euambiy cQ'^'tb at r bvni Hm adi flt a tiaat WfH. 12 '4 LD«13S-J ' LOUlJS-t ^^itintlir«ia3«rpafitet4onl|r r | LDM13S-3 ,n jUnnvtot t ft' i.- lorn Jinij inpgiH undsr 2 Of . £70 nm ^ tmtt than t iriW prodmt m 8 mni btam 2 \mafi !70» ^ue@ t»» 1B0«i MS*i m» 10999 irog? »$99 19949 msi He-Ne TUBES artd m «9r fjpdtyl ? AAA tiarMfiM EHS CQl'mjfi'i'J tens Aw^Cfl' ?4 99 ?J71 ?1 ^ POWER SUPPLY ROBOTIC ARM KIT ■ * *i2v^i4A • •Sijfi ?■ I. K 5 i" W « ? ■■ H STOCK B PS 1003 PfllCE S13.99 ^ ^.'Ls'ii wdfit of«0 cordirtv^ ici icifi laiAj of ptitbng iDQciiriAf tofflp*** pfodudt ro&ot«CA am iifif»no iheif wOf into mwo and more induftrwi Tlv Rotiat^c Arm KiT It an educAiiOfi^l kit thai tchicli09 ijasm TO^Mcatm lundAmtrfiTniiaawui! es loiting your own mcslot iHiiUs CommfiniJ 1I to c>erfo»m mnipio (Ai-ks. STOCKS* YOt PRICE S43.39 An, ingeHtgom roMt rhit knomt ho* 1.9 m^td tiiitm^ w^.iis Tti^i robot emit! an mfra-fod b(jnrn which d62-lQl9. ilS IS AN EXPANDEO'TYPE AD WITH A NT SCREEN. See how it jumps out on the ,^e. To order your ad in this format calcif- e ths cost at S5.90 per word for tlie ex* nded-type and the tint background. CABLE TV DESCRAMBLERS * CONVERTERS ★ and ACCESSORIES. SAVE MONEY. DON'TRENT? PANASONIC, JERROLD, OAK. PIONEER. SCIENTIFIC ATLANTA AND MORE LCVEST PRICES FREE CATALOG To'-MSTNriSOO) 234.1006 FREE CATALOG! 1-800-648-7938 JERROLD HAMLIN OAK ETC CABLE TV * Sp&aa! Oaaier Pricesf • CofVfyarQ our Low Retaif Prices} ■ Gvaram&ed Pficss £ W&rrantiesf REPU8UC CABLE PRODUCTS, INC □ 4080 Pa/adise Rd. #t5, DwRE392r^ 3 Us Wgas. NV 89109 CZJ Fd* al Oth#f infermaJion (702) 362 9026 DESCRAMBLERS CABLE W EQUIPMENT cm TOLl FREE 1-800-228-7404 ca5| OUR rvoouos/K PBOOFI 30 DAf MONEY BACK GOAfpr iKV min m M Hcia M oui VM^^ WCARf?/ All WUOftlSAm BEST PRICE BEST SERVICE THf OOKNBCnotI J^<^ NU-IEK ELECniONICS CALL OR WRTTE 1-612-260-6031 Si.--;. Stop Srr»oking. ^ Amertcan Heort AssociQlion MflRK V €L€CTRONICS, INC. Competitive Pricing * Fast Shipping Since 1985 A indicates level of dirficulty in ihe assent bli rig ol Oiir Products. * TAJ 77 Special offer will be given to the purchase ol Amplilter + Metal Catiingt + Power Transformer] 3£00 « ^ IN CA 1'800-S2T'MARK (orders only) DtnSIDE CA t-80D*423^FIV£ [m^m QRlf ) QROEHBY FAX {213} SSS-eSSa CATALOG & INFORMATION (213) 830^6934 Beginner A A intermediate AAA Adva nced * F ully Asswrtbte d MticauMioiis m uam rjb-300 DESCRIPTION 'Ttm* 1 JOit im Im PT<-tto^fM Ptmm *w am. lC»>l?CW> JOCSteMP»tWMl lPgl AAA A »« an t7n I9(a am Jin mm mm mm not »m r^da moil IV 23 rv-36 TY38 rv-4j TT^ n^f CI? DftCN#1Klil hrirtrt« flimw CqMtV lint I fe^CMit TtOiQaRmltMwA 3311 4614 in* ma ■?« }(SK tun H 'I 73 is .... rtv t D-MTCHnG L&iifti r tr f T4 im tAjfrA f a 2790 lGr1i?4 r ir 11 . IA«t UrSCQTATTeift.? rA^lK2 TATOaU L£TSS ■ If ll^r tA lAlOa UC} TA1^a) TA^om TA^UV} lErTiii 3vitr r tA^*:i TA^toa fAi^QC ti T?gvfe : Pirn 31 io 3«0D 9- o m o o 99 SSfUtl J r AAA 4'. HifttCWfi &^ll fmAICElEaf CjaiAAA MOO Hm 41 24 »D Mm M» ' T,' ■ ? M TS^ iM.Saik fUpa U jm tAITJA IA4T7 inoe 3a 00 nm 1700 ilea iitoBCd«i<^^C^Cvn tao^On*^ OwsoandiCDn cydM cot} Vii>«tii^ iXr-r^vmrntnta *it»f^t^i^r^^-^vx^''^ t*oaiJF*u*flp,iis*vw BufindSsA Showfocrfl hows iPaoSc TirTie> osa^toLfi R«wu^h^uwiCMDjr'w^^sr«r»n^ MQn thru Fit ^ am ta 5 OO pTI MARK V ELECTRONICS, INC. -8019 E. Slauson Ave, Montebello, CA 90640 H CIRCLE 9S ON FREE IKFOFtMATION CARD Your Natural Resource for Wide Test/ Measurement and Prototype Equipment minvkindt ur]>riirim-pitij(: ^(id citcun ^pi. t^rg^ft miKkii Ui\m^ i hci^^-duiv jluminiin) backing wiih ^ittltigp" ind gmunding pt*^n. Part Dim* OmUd Biniiin|( JE21 »-'S*_M2^ Am\ (I S4,9S JE25 *vi«i»i*'i m\ \i 6^95 JE24 UM%SM^ }MA\ : Pan mm. CenUd Uindlin|! PcMtit* Pmo Price jK26 Mt'^iV?'^ 2JW 4 22.95 JE27 Uio 4 3L95 OotdSffar 20JVlHx DuqI Trace Oscilloscope [ritin|![ jnd mci<»4iRmvni nocdi? J cjfmri irdudt J 6" ('R Tdiipbv, Af5ii hinilwidtlk JriiinlKItii lOMHiL Tht (iiildHtjr CKilliH>L()fie uimo lAiih rntx piobci. hah prmtr ciud, npmridfl rtunijjL H:hfliiJiic\ jcul hkuk 4iui vi'mn-^ dugrjni, lii;lu\ivi^ht jnd [^ruhlc with $399.95 MIC Cable Assemblies for GS7020 BNCl BNCtM) 10 BSGMf Kt,^ A/UtB'U S5.95 BNCl mem ti> Klut^ Hoak RGIT4 ^91J™*,,.^.95 BNC3 BNOMI iti H<»1 RGI74 CJ9^U^......,3-95 ^4 P J AMECO ElfCmOMC COMPOMEM15 COMMUTE n PRODUCTS 24 HiHir TiTjl'I'rcc Orda Hotline 1 •800*831-4242 Minioture RS232 Breakout Box I UiTts ij,uikkty Jiid r>L%ily, jumprf * jihI mMhtnr (imjI lotkc «) BBMF „S9.95 ll$332 tnterfoce Check Tester HHpi jvfml vhfiwing villi simple intcriJiir prufilciHA. \n mofid) the Crr252 will I he lurus iiF lin^ 2» 3» 4i» 5^ 6. U . l'> jfid atl. I he trr2,12 incliidcs tnjU' til fcntjic DB2^ tiinnctn>r^, CT232.„. SI 4.95 Metex Hlgital Multimeters ^TJiti^, AO [ X. tuirc n ' . M5800 i.sij.piMuJi.mcffT $39,95 e' * '^i Mi6^ M5610 Vit^tMulrimcTcr S59.95 «tiit l i^iJJW! - ,559*95 ^ 401*'' ^ *' r K^ \ & t .574*95 \ 0^^^ - ^1°''^^. M4650 -i-suppiw/i' & i ftiJd ^wiEch.« S99.95 \ Jameco Logic Pulser I Jameco Logic Probe ' (:<»BijtjiibIc *ith TTt^ DTL RTl. KTL HML Ml>SinJCMOS lO > IMU Si-riL input impcdiacc * Ihit&o' mnk autpul turtcnt: EOvnA * Squat? carrmt mutfiiit: iraA * Audtbk lonc LP54§. .516.95 i(E)FROM Progrommer 1 Sockef 16K-1Me9 • \Uk i iL-qurthy Hj:>MH/ • Minimum dctRtiWc pul»c: lOm ■ 1 inpur inrf^damr • Max, *uppfi- ^i^Iugr. ^l^V - TtlxhtMd UnJ*C*>V iOjV. (Hi) *2.}\' itilV • CMOS ihioiwki (Lit .M>^ S24,9 UVP iPROM Eraser * Buil(-in Ndrrti.il, Intdligcnt I&H.and Quitk'puk 4lgtiri£hms • XP60f>OA Eict'tJcd for opera [ion • Software included XP6001 .SI 19.95 XP6000A AtUpictOid .......$29*95 • KM^-* ill IIPROM^** Kri«^ I chip in IS niimno^ndH^hip in 21 1 " DE4„ .-SS9*S EPROMs - lor your programming needs TM.S25i6 S4.25 TMS2532A 6*95 TMS2564 5*93 TMS27I6 *_5*95 l?02A...^ 3.95 2708 ™„4.75 2716 3*39 2716-1 3.75 27C16**« ._^4.25 2732.*. „«4*95 2732A-20,„. .«4.49 2732A-25 3*49 a732A-45 ..2.95 27C32 — .**** 4*75 Prict Pan No. Jifkt 2744-20 $3,95 2764'25 .«3"S 2764A-20... J.75 27&4A-25*— ,.^.-3*19 27C64-15 — ^. 3-95 27C64-25,,™..«3*25 271280TP.^ 2,49 27I2R-20..„ .7*95 27128-25 *.™7*75 27l2aA-15 4.95 27l28A-20..**«**«4.49 27 IZBA 25 3.75 27C128-15,,,,, — 5,75 27C1 28-25 .7.95 272560TP S3,7 27256-15 *5*4 27256-20 *^4.9 27256-25.-.,^ .4.4 27C256-15™™5.9 2TC256-20™««4.9 27C256-25 275120TP ^43 27512-20,^ ^6.7 27512-25 5.S 27C5I2.15 .6,7 27C512-20... 6.'1 27C5I2-25 5.S 27C010-15..«......9.^ 68766-35* 4.9 * Partial Listing • Oifer 4000 Electronic and Computer Components in Stock! too CIRCLE 1 14 ON FR£E INFORMATION CARD Selection & Competitive Prices Computer Upgrade Products and Electronic Componettts Upgrade your existing computer systetni Jameco Jamec0 80386SX Motherboard ' /. n. .■■ ,i!k ■.'..11! .i^\rj[mn * N j[!f.,riv,.^iu»S\!UHj RAM » Inu t ^iU.^iH"SX^tli)lTlpaIlbk nulh cofinxmcK xnckct • AMI mos JE35I6SN...... ^299.95 Cotiiier IHE Hord Drives :P3000 lUMh .l.*^"* rrDmc_....S249.95 .V5" l ow Pmlli[: ...S479.9S 2> 1 10. 29 .19 117-,^ 35 .25 Ii20,«. .„ ^9 .19 B2.... 35 .25 147 .B9 .79 i74 39 .29 i76 45 .55 t86 45 35 !89.. 2,95 2.75 i90..... 59 .49 ill I 49 .39 1192 ....79 .69 il93«......... .79 .69 Linear ICs* inN a . 1-9 10* 1082CP , $.59 S.49 ^mrr. .65 .55 ^B24N 35 .29 V(336Z - ..L05 .95 vf339N 39 35 E555V ...29 .25 V155(jN.... .49 39 Vf723CN .49 .39 W74ICN ..29 .25 V114S8N 35 .29 vll48flN......... 45 .39 V114B9N ...45 .59 LN20O3A 69 .59 ^914N..... .1.95 1.75 E5532 1.19 1.09 I05T 45 .41 I12T .45 .41 * Gt// fir J (mmpieit Iniing of iO Memory 412^120 SI looorio DIP 120(11 _S1.79 2^ Dip lSOi» 1.69 I MB DIP mm .,5.99 \mD\r ^oon% .5.49 !ijrr ioori _.i«,95 :%KM\iM 20.95 IMHSirP 84»m_59.95 Miscellaneous Components* Potentiometers i Lirv JtUHc imvtn dhmi iPfa ipKC nurbki I mu IK. ^K. lOK. 20K. UK. mK. \StH] S.99 ...89 Many more Upgrade Products atuiilabUi Connectors Toshibo 1.44MB 3.5" Intemo) Floppy Disk Drive - IBM fOXlVATanciccKnpjjililc* • l'imi|tjiib1r with DOS ^fnton* .ij or Hi(^ • Inclinlct 4ll nrcciiin' iiutillatjc?ri hjrtl^aie • 1 .44MII Itirnurrfd hi^h dt■n^t^v mfuJc ■ 7i(lKH forns.iticd Inw iUtimii. iiuiitjf • "Sm', 1 'H V X i ixuliI drive \\tc\ i56KU.. .»««„„»„.499-95 IC Sockets DcHTiption Price OB2SP Maks 2 3 -pill S.65 DB2SS I'cmalc, 25-piii .75 DB25H Hood 39 DB25Mlt .Mcul tHood 135 LEDs XC209R S.14 XC556C ri 3/4jGrccn) .16 XC556R Tl 3/4.(Rcii) J2 XC556Y rt 3/4. (Yellow) .16 8LI* S.10 8WW S.49 14LP .11 14 WW' .69 16LP -12 J 6 WW .79 24LP .19 2i>X^' 1.15 Z8LP .22 2SWW 139 401-P 40WW 1.89 St^drruti Sid mLiri W //riiirr Ping jwvlm Aho Aiytiiithlf 45PXX 3/4Wait45 Turn. 65PXX 1/2 Wan. I Turn . l^nsistors And Diodes PN2222 PN2907 1 N't 004 2N2222A lNi735 2N3904 JMT123 sri>T, tlri On iTiJSiLlc) SI. 15 206-8 S nST . I f.-pj n i 0} V I 1 *09 MPC121 spim OR4>frun rrog^i 1.19 MS 1 02 Sr^l . Vttimcn ujy ( r'u%h- Milium} 59 24- Hour Toll-Free Order Hotlinci 1.800*831-4242 Call or Write for a FREE 90-Page 1992 CatalogI S30.00 Mininium Order • Daia Sheets - 50< c*th $.12 1N75I S.I 5 .12 C106B] .65 ,10 2N440I .15 .25 1N4148 .07 .25 2N3055 .69 IN270 .25 Switches J AMECO ELECTRONIC COMPONEISTTS COMPUTER PRODUCTS 1355 Shorcway Road B^lmoni, CA 94002 ¥f\Xi 1*800*237-6948 BBS Support: 415'637-9025 tiiicrit4iJOJial Si]» * CuiUimrr Service * Technk^L A.%iut4ini;e * C«dU Ocpanmcnt • All Oilier Ini^uifJCi: 415-592-8097 * 7AM * 5PM P.S.T. ( A Rriiilf riti ^M ^7V^ or K, S\ \iln Tj* Irrms uibfccr lo jilibdjiv Jnd pm» witc. jiijitioiuL lu I :d ft) o m 101 anCLE 114 ON FREE LNFORUATION CARD Cable TV Descrambler Kits Universal Kit S55.00 incLu{l(»s &\[ parts and PC Board. tncludtd IS ih6 iic iiclaptor or ^ndcisure- Tri-Mode Kit. $39.00 tnclud«s all parts, PC B&ard and AC AaaptD-. No; SB.3 Kit S29.00 included aEi Dan&. PC Soard and AG Ad^aptcr. ^Joi: ir^clud«plbet\ Call To[I Free 1-800-258-1134 Visa, MasterCard & COD M & G Electronics, Inc. 301 V^estminister Street Providence, Rl, 02903 cmcue 190 ON free [nformatiok card 102 CABLE TV DESCRAMBLERS THE MOST ADVANCED TECHNOLOGY IN CABLE EQUIPMENT: • BASE BAND - JERROUD • PIONEER • TOCOM • HAMLIN * ZENITH • SCIENTIFIC ATLANTA * OAK For out of this world prices call WORLDWIDE CABLE 1 800-772-3233 FREE CATALOG AVAILABLE 7491 Cr5 N. FEDERAL HWY, , SUfTE 1 42 BOCA RATON. R. 33487 MC / COD / VISA MQ FLDRQft SAlS ADVERTISING INDEX R ADIO-^ELECTnONICS does not assume any responsibility for errors that may appe in the index below. Free Information Number Page im AMCSa!^ 78 75 Atv Prt^dticts . 97 107 All Electronics . 96 I HB A iiier j cu n Rei ianct I n c 79 84 Appliance Service 79 77 B&K Precision \5 im C & S Sales m — CIE ...H, 40 184 Cal>le Warehouse. . 78 — Command Productions ........ 77 127 Peco Industries . . 79 177 Electronic Goldmine ...... 94 — Electronics Book Club 23, 84 121 Fluke Manufacturing XV2 186 Global Specialties 25 — Grantham College ,45 m Heathkit... 13 192 Hewlett Packard , . . 7 — ICS Computer Training HI 114 Janieco I(X). 101 115 Jensen 'Ibols , .79 I9fl M&G Electronics , 102 89 MAT Electronics . , . 77 53 MD Electronics 94 I7H M JS Design , . . 79 93 Mark V* Electronics 99 — NRISchools.., .21. 32 180 Optoelectrtjnjcs 29 56 Paria Express , . . . 95 183 People *s College 27 78 Radio Shack 3 187 SCO Electronics 52 Free Information Number Pa — Science Probe . , , , . . C 92J79 Tektronix .... 123 Test IVotHiS . . . . ~ The School of VCR Repair 191 Unicom I8H U.S. Cable 181 J82 Viejo Publtcalions ......... L 189 Worldwide Cable ... t ADVERTISING SALES OFFICE Gernsback Publications* Inc, SQO-B Bi CountV Blvd. Farmingdale^ NY 11735 M516J 293-3000 President: Larry Stockier For Advertising ONLY 516-293-3000 Fax 1-516-233 3115 Larry Steckler publisher Christina Estrada assistant to the President Arline Fishman advertising director Dcinise Haven advertisinig assistant Kelty McOu^de credit manager Subscriber CtJStomer Service 1-800-288-0652 Order Entry for New Subscribers 1-800-999-7139 7:00 AM ' 6:00 PM M F MST SALES OFFICES EAST/SOUTHEAST Stanley Levltan, Eastern Sales Managei Radio- Electronics 1 Overlook Ave. Great Neck. NY 11021 ^ '5 1 6-48 7-9357, 1 ■ S 1 6-293- 3000 Fait 1-516-487-8402 MIDWEST/Texfis/Arkansas/Okta. Halph Bergen I Midwest Sa^es Manager R^dio- Electronics One Northfietd Plaza. SuFte 300 Northfidd. 1160093-1214 170B 446-1444 Fax 1-708-S59-0562 PACIFIC CO AST/Mountain States Marvin Green* Pacific Sales Manager Radi o- E lectmni cs 5430 Van Nuys Blvd. Suite 3!6 Sherman Oaks. CA 9 140 J 1-818-986-2001 Fax 1 -81 B 986^2009 RE Shopper Joe Shore, National Representative P.O. Box 169 Idyl I wild, CA 92549 1-714-659-9743 1^ 1-7t4-659 2469 CIRCLE 189 OK FReE INFORMATION CARD science PROBE! — the only lagazine devoted entirely to Amateur icientists! If you are fascinated by sci- nce in all its many forms ... if you can't tay away from a microscope, tele- cope, calipers, or test tube — we in- ite you to share the wonders in every ssue of Science PROBE! You will join community of Amateur and Student Scientists who enthusiastically seek cientific knowledge or follow scientific ursuits for their own sakes and not lerely as a profession. )btain your next issue of Science *ROBE! by visiting a quality News- tand, Convenience Store, or Super- larket or by reserving your personal opy through the mail by completing le coupon below. rom your very first issue of Science ^ROBE! you will be involved in a world f scientific facts, experiments, and tudres pursued by amateur scientists /ho are university students, investors, cademicians, engineers, or office /orkers, salesmen, farmers— whose ^uest is to probe into the mysteries of cience and reveal them to all. Han to become a Science PROBE! Bader! Welcome to. . . EIMCE The /Imateur Scientist's Journal Embark on an irresistible new journey into the realm of mystery, challenge, and exploration! The perfect magazine for the budding scientist, the serious amateur, the professional who would like to relax, and those who simply want to gaze at the stars. Articles to appear in upcoming issues of Science PROBE! are: How an Amateur Mapped the Milky Way Make your own Seismometer Operate a Solar-powered Weather Station Grow Crystals Automatically Experiment with a Saltwater Aquarium How to Keep a Science Notebook If you're fascinated by science in all its many forms, if you are compelled to experiment and explore, then Science PROBE! is your kind of magazine! Science PROBE! 5Q0-B Bi'County Boulevard Farniin|,'dale, NY 11735 7RC27 ■1 Please forward my copy of Science PROBE! as soon as it c don't Ix surprised to discover some unusual tools in their service kits. Signal flares, for instance, On the other hand, portable test gear from Tek gets technicians to the root of * •A the problem long before the problem gets to them, Evei^thing from oscilloscopes and spectmm analj'zers to handheld DMM As a result, your customers will be bad on their feet happy for that. Not to mention a whole lot nicer to in that'll seem like no time at all. They'll fc E" work with. For your employees' sake, get 1 touch with a Tektronix representative today Or keep an eye peeled for signs of distress. TALK TD 1IK/1-BD0-42S-22pi Tektronix y^tA and Measurement CIRCLE 179 ON FREE INFORMATiON CAHD