(]j 4*783 UILD VOLTAGE DOUBLERS FOR HIGH-VOLTAGE PROJECTS ECHNOLOGY - VIDEO - STER =t>ii>t»]iMai TEpS - SERVICE uild this high-performan PECTRUM NALYZER or a fraction of the cost of ;ommercial units! n intuitive look at LECTROMAGNETIC HEORY uild R-E's LECTROCARDIOGRAN ;o keep tabs on your heart Ise our RS-232 ERMINAL/MONITOR o solve your serial nterfacing problems Build an electronic SPEAKER PROTECTOR : or your stereo system Jnderstanding and buildii JOLTAGE DOUBLERS "or high-voltage application: IQJpM * "a.%r;sa. SUB :*"• ' "71896"48783 111 1 $2.95 US $3.75 CAN IHJ:l)kH:M>J!l xxxxxxxx CAR-RT SORT ** CRQ3 75D456HRR5165S1D93 D3 89 NOLJ 93 RE FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT 7 SERIES II 8 New Meters. 8 Old-Fashioned Values. Introducing Fluke's 70 Series II, next- generation multimeters that meet the increasing demands of your job and your budget. Consider. At the top of the line, the new Fluke 79 and 29 deliver more high-performance features - capacitance, frequency, a fast 63- segment bar graph,Lo-Ohms range, Smooth- ing™, faster ranges- than DMMs costing much more. At the entry level, the new model 70, Fluke's lowest-priced DMM ever, delivers unparalleled Fluke quality at a price comparable to "dispos- able" meters. And in between are all the models that have made the 70 Series the most popular DMM family in the world - updated, refined and delivering even more value than ever. "BASICS" REDEFINED No matter which 70 Scries II you choose, you get simple, one-handed operation. High resolution. And built-in, go anywhere reliability. Automatic Touch Hold® - standard on every model - locks the reading on the display and signals you with a beep, automatically updating for each new measurement without a reset. Leaving you free to concentrate on your work, not on your meter. YOUR BEST CHOICE Best of all, every 70 Series II is a Fluke, backed by a worldwide service network and an industry- leading 3 year warranty. So the next time you're in the market for a new meter, ask for the one that guarantees old- fashioned value. Fluke 70 Series II. For more information call 1-8Q0-6789-LIT. Or call 1-300-44-FLUKE, ext 33 for the name of your nearest Fluke distributor. CIRCLE 121 ON FREE INFORMATION CARD Fluke 79 Series II S 29 Series II S1SV 4000 Counl Cip jlal Display 1999 9 in H; & -«- ) 63 segment Analog Bar Graph 3% Basic DC Vollage Accuracy AuiomaK Touch Hold" Diode Test. Auditle Conlinuity Beecer_ Amoranging. Manual [tanging Hoisler wiihFtei Stand 1 " Frequency Cotinler lo oret 20 kH; Carjacilanee IQpF »o 999Srif Lo-Dhms Range win Zero Ca I ibral or Smoothing"" 7DC Hmiis Battery Lite (aftaime) 3 year Warranty 79/77/75ff3/70 rut measurements lo 4800 V-A 29/23/21 lor hrgtier energy measurements. 'Fluke 70 Series II sufjjKlefj U.S. list prices range Iron) 169 to 1185. Jrjll Flute Mir) Co. Inc P.O Boi SOM M.S fflK E*rS[ WA 9aSHMMfi^ M^* l ?]:,7T,7T H ^g. "-cie^^E^r PAGE 55 ::: V O L T ft G E DOUBLER/\R3JaUO0 ■ m jtiiKyuiCTTc 6 VIDEO NEWS What's new in this fast- changing field. David Lachenbruch 22 EQUIPMENT REPORTS Sharp PC-3500 Pocket Computer. 69 HARDWARE HACKER Caller identification, and more. Don Lancaster frjaMsw* MHM S5£=S55 PAGE 61 77 DRAWING BOARD A PC board for our audible logic probe. Robert Grossblatt 80 AUDIO UPDATE Audiotapes: past, present, and future. Larry Klein 80 COMPUTER CONNECTIONS The friendly Amiga. Jeff Holtzman 96 Advertising and Sales Offices 96 Advertising Index 8 Ask RE 14 Letters 84 Market Center 31 New Lit 24 New Products 4 What's News > c a c CO o z o cr I Q < IE For examining the components of a signal spectrum, you can't beat the versatility and convenience of a spectrum analyzer. It allows you to measure parameters such as power, frequency response, harmonic dis- tortion, and the amplitudes of com- plex components. All those func- tions don't come cheap, however — unless you build our PC-based ana- lyzer, which costs about $300. Con- sisting of a single printed-circuit board, the spectrum analyzer re- quires a modestly configured PC to act as the host machine and display. The calibrated 0.1 + 810-MHz ana- lyzer provides repeatable, accurate measurements of frequency and power, and includes an array of spe- cial features. To get started, turn to page 33. mm THE SEPTEMBER ISSUE GOES ON SALE AUGUST 6. BUILD A MULTIMEDIA PC TO TV CONVERTER Put computer power to work in your home videos. BUILD THE MICROANALYZER For servicing microwave ovens, this handy tool will test in-circuit, high- voltage diodes, capacitors, magnetrons, and power transformers. BUILD A TELEPHONE LINE SENTRY Protect against losing that modem connection and other phone-line annoyances. AN INTUITIVE LOOK AT ELECTROMAGNETIC THEORY In Part II, we look at electric phenomena. As a service to readers. RADIO-ELECTRONICS publishes available plans or information relating to newsworthy products, techniques and scientific and technological developments. Because of possible variances in the quality and condition of materials and workmanship used by readers, RADIO-ELECTRONICS disclaims any responsibility for the safe and proper functioning of reader-built projects based upon or from plana or information published in this magazine. Since some of the equipment and circuitry described in RADIO- ELECTRONICS may relate to or be covered by U.S. patents, RADIO- ELECTRONICS disclaims any liability for the infringement of such patents by the making, using, or selling of any such equipment or circuitry, and suggests that anyone interested in such projects consult a patent attorney. RADIO-ELECTRONICS. (ISSN 0033-7862) August 1991. Published monthly by Gernsback Publications. Inc . 500-8 Bi-County Boulevard, Farmingdale, NY 1 1735 Second-Class Postage paid at Farmmgdale. NY and additional mailing offices. Second-Class mail registration No. R1251662B0. authorized at Toronto. Canada. One-year subscription rata U.SA and possessions SI 7.97. Canada S25.65 (includes G.S.T Canadian Goods and Services Tax Registration No, Rl 251 662801. all other countries $26.97. All subscription orders payable in U.S.A. funds only, via international postal money order or check drawn on a U.S.A. hank. Single copies S2.95. 'C 1991 by Gernsback Publications, Inc. All rights reserved. Printed in U.S.A. POSTMASTER! Please send address changes to RADIO- ELECTRONICS. Subscription Dapt., Bo» 55115, Boulder. CO 80321 5115. A stamped self-addressed envelope must accompany all submitted manuscripts and/or artwork or photographs if their return is desired should they be rejected- We disclaim any responsibility for the loss or damage of manuscripts and/or artwork or photographs white in our possession or otherwise. Electronics Hugo Gernsback (1884- 1967} founder Larry Stockier, EHF, CET. editor-in-chief and publisher EDITORIAL DEPARTMENT Brian C. Fonton, editoi Marc Spiwalk. associate editor Kim Dunleavy, assistant technical editor Tnri Scaduto, assistant editor Jeffrey K. Hottzman computer editor Robert Grossbf att, circuits editor Larry Klein, audio editor David Lachenbruch contributing editor Don Lancaster contributing editor Kathy Terenzi, editorial assistant ART DEPARTMENT Andre Duxant, art director Injae Lee, illustrator Russell C Truelson, illustrator PRODUCTION DEPARTMENT Ruby M. Yee. production director Janice Box, editorial production Karen S, Brown advertising production Mareella Amoroso prod ucti on ass ista n t CIRCULATION DEPARTMENT Jacqueline P. Cbeeseboro circulation director Wendy Alanko circulation analyst Theresa Lombard* circulation assistant Micbele Torrillo, reprint bookstore Typography by Mates Graphics Cover photo by DrvefStfiad Photo Services Radio-Electronics is indexed in Applied Science & Technology Index and Readers Guide to Periodical Liter- ature. Microfilm & Microfiche editions ere available. Contact circulation depart- ment for details. Advertising Sales Offices listed on page 94. RadiO'Etectronics Executive and Administrative Offices 1*516-203-3000. Subscriber Customer Service: 1 800 288 0652. Order Entry for New Subscribers: 1 800999-7139. ^ The Audi: Bureau ol Circulation 5 WAYS TO STOP WASTING TIME IN ELECTRONICS. Stop wasting your time soldering. Save hours of soldering, desoldering, resoldering with Quick Test™ sockets and bus strips. Connect/ disconnect resistors, capac- itors, transistors, ICs, etc. as fast as you can push in/puli out leads. Interlock for limit- less expandability. Priced as I low as $1.60, you'll wonder how you've done without them! 5-color coded binding posts and 17 sockets, for over 4,560 contact points. Lifetime guarantee American- made. Affordably priced 2. Stop wasting your time breadboard- ing. Here are three popular PROTO BOARD" Brand solderless' breadboarding systems that meet any budget or time schedule. First the diminutive PB-10's 840 contact points and 3-color binding posts. PB-102has 1,240 tie points, accepting up to 12 16-pin ICs. Finally, PB-103, with 2,250 contact points, and up to 24 16-pin capacity. They're affordable, American-made lifetime guaranteed. You'll soon see why PROTO BOARD Brand is Today's Standard for Quality in Breadboarding. Stop wasting your time jury-rigging large numbers of circuits. Here are two oversized PROTO BOARDS Brand, with expanded area, tie points, and more to keep your ideas together. PB- 104 features 3,060 tie points, which can handle to 32 16-pin ICs with ease. Four color coded binding posts, and roomy 9.2" x 8" metal panel make it big... but simple. The humungous PB-105 lets you load up to 48 16-pin ICs, and much more onto its 4. iRD Brand is 3. Stop wasting your timeplugging- in external power. We've added the power to the breadboard. And, what power! Up to triple voltage power, +5V, + 12V, - 12V, reg- ulated/current limited and DC. Up to 2,250 tie points, with 24 IC capacity and 14 pin DIPs. Now you can create, test and modify TTL, CMOS, Op-Amps and even microprocessor circuits. Plus, there is the standard Global Lifetime Guarantee on the sockets. And, wait 'til you see the modest prices! PROTO BRAND 5. <© GLOBAL Stop wasting time designing computer circuits. Now you can use your solderless breadboard concepts for designing accessory " circuits. PROTOCARD* is a PROTO BOARD Brand which fits any standard slot in your IBM, PC/XT or PC/AT computer. Some modules even include built-in basic decoder circuits for memory and I/O addressing. Breadboard areas up to 3,360 contact points. Buffered versions eliminate loading of pc buses. > c Q C V) Global Specialties. An Interplex Electronics Company. 70 Fulton Terrace, New Haven. CT 06512. Call toll-free for details IQftn JT"70 inOO QDC^^IAITICC TeleDhone ' < 203 > 624-3103. r. Inlerplex Electronics 1989. "OUU"D I d." lU^lO VlCvlMLiI ICO A;l Globsl Specialties breadboarding products made in USA CIRCLE 190 ON FREE INFORMATION CARD A0011 MMMlUm- A review of the latest happenings in electronics. o z o tr w 6 Q < DC Superconducting transistor used in electronic circuits Made from the new high-tempera- ture superconducting materials, a superconducting transistor de- veloped jointly by scientists at Sandia National Laboratories (Albuquerque, NM) and the University of Wisconsin, Madison, has been used in function- ing electronic circuits. Dubbed the Superconducting Flux Flow Tran- sistor CSFFT), the device can be con- sidered the superconducting analo- gue to the field effect transistor CFET), the "workhorse" semiconduc- tor that is in wide use worldwide. A transistor is an "active device" — one that can produce a power gain — and the SFFT is the first transistor made entirely from high-temperature super- conducting materials. Circuits incor- porating the device can operate above 77 K, the temperature of liquid nitrogen, a widely available and inex- pensive coolant. The SFFT consists of parallel, weak superconducting links that sep- arate two pieces of semiconductor and a control line to provide a local magnetic field. While a FET's output current is controlled by changing the input voltage, the SFFT's output volt- age is controlled by changing the in- put current. Acting like a gate, the current in the control line alters the magnetic field in the active region of the device, which modulates the out- put voltage and can provide gain at very high (microwave) frequencies. The team of scientists took the de- vice and coupled it with passive mi- crowave components in real circuits that represent the essential compo- nents of electronic communications and signal processing technology, in- cluding amplifiers, oscillators, phase shifters, and mixers. Microwave am- plifiers built with the SFFT show a gain of 1 dB at 4 GHz. The SFFT has also been used to make mixers- — de- vices that mix together two frequen- cies to produce a different output frequency — that operate at up to 35 GHz. The SFFT can serve as an interface between conventional, low-tempera- ture superconducting electronics and semiconductor electronics. The SFFT has a low input resistances and a reasonably high output resistance, which allows it to serve as an active link between superconducting and semiconductor circuits. In Sandia's experiments, a Josephson junction drives the input of an SFFT, which then drives the gate of a field effect THIS PHOTOMICROGRAPH of a superconducting flux flow transistor (SFFT) shows the source (upper right), drain (lower right), and the control line (left). transistor. Current research concen- trates on developing a technology around the SFFT that includes pas- sive and active components in a whole family of applications. CEBus developments CEBus, the home-automation standard being developed by the Electronic Industries Association/ Consumer Electronics Group (El A/ CEG), allows communication throughout the home between a vari- ety of electronic products over exist- ing power lines, twisted pairs (telephone), coaxial cable, and in- frared means. The infrared and twist- ed pair sections of the CEBus (Consumer Electronics Bus) stan- dard have been approved as interim standards. The new interim infrared standard covers the transmission of signal to integrated CEBus prod- ucts — for example, the interfacing of security devices with telephone equipment — while twisted pair stan- dard facilitates flexible room-to-room communication. The interim stan- dards are considered by the EIA/ CEG to be a major milestone on the road to a complete, overall standard, which is expected to be announced by the end of this year. The first public working display of CEBus technology is the Bright Home, in Indianapolis, which opened at the end of March for a six month period of public tours. The Bright Home links a variety of electronic equipment and appliances into a common intelligent-control system. The Bright Home display is intend- ed to demonstrate the "building- block" approach to CEBus tech- nology, which allows consumers to integrate as many CEBus products into their new or remodeled homes that their budgets and needs dictate. Among the various companies con- tributing products to the Bright Home project are Panasonic, Sony, and Thomson/RCA: the CEBus products and technology are provided by Hometronics, an integrated elec- tronics consultant that's located in In- dianapolis. RE (1) Talking Multimeter. Timesaving speech output! Press a button on the probe and this meter calls out the reading in clear English while displaying it. Features include full autoranging, liquid crystal display with low-battery and over-range indicators, continuity beeper, diode-check mode. #22-164 99.95 (2) NEW! Building Power Supplies. Easy-to-understand, 96-page book explains linear and switching supplies. Includes complete plans for building five useful supplies with Radio Shack parts. #276-5025, 4,95 (3) Mini Audio Amplifier. Great for computer voice/music synthesis, signal tracing and more. Has a built-in speaker. >fe" headphone jack, Va" input jack and volume control, #277-1008 11.95 (4) Digital Logic Probe. LEDs and tone outputs reveal logic states instantly. It's the fast way to check operation and pinpoint problems in all types of digital circuits, #22-303 16.95 Parts Special-Order Hotline. Your local Radio Shack store stocks over 1000 popular electronic compo- nents. Plus, we can special -order over 10,000 items from our ware- house—linear and digital ICs, tran- sistors and diodes, vacuum tubes, crystals, phono cartridges and sfyli, even SAMS 1 service manuals. Your order is sent directly to your Radio Shack store and we notify you when it arrives. Delivery time for most items is one week and there are no postage charges or minimum order requirements. (1) Shielded RS-232 Jumper Box. Top-quality inline D-sub 25 adapter. Wire the included jumper wires and board to suit your need. #276-1403 9.95 (2) RS-232 Tester. Dual-color LEDs monitor seven data/control lines to help you spot problems quickly. D-sub 25. Connects inline. #276-1401 14.95 (3) Grounded -Tip Soldering Iron. 15W. #64-2051 7.49 (4) Vacuum-Type Desoldering Tool. #64-2120 6.95 (5) Locking Forceps. 6" long. Stainless. #64-1866 4.95 {61 Rosin Soldering Paste Flux. #64-021 1.79 (7) Lead-Free Solder. 0.25 oz. #64-025 1.99 Over 100 soldering items and tools for electronics work are in stock at Radio Shack! (8) 10A Microwave Oven Fuses. #270-1256 Pkg. of 2/1.29 (9) 2-Anip Fast-Acting Fuses. #270-1275 Pkg. of 3/790 (10) 5-Amp "Blade" Car Fuses. #270-1205 Pkg. of 2/89C Big selection ot fuses, holders and accessories in stock! Computer/Business Machine AC Power Cords. 6 feel long. (11) Extension. #278-1259 4.99 (12) With Space-Saving 90° CEE Connector. #278-1260 5.99 (13) With Straight CEE Connec- tor. #278-1257 3.99 Since 1921 Radio Shack has been the place to obtain up-to-date electronic parts as well as quality tools, test equipment and accessories at low prices. Over 7000 locations to serve you— NOBODY COMPARES Prices apply a! participating Radio Shack stares and dealers. Radio ShacK is a division of Tandy Corporation CIRCLE 78 ON FREE INFORMATION CARD (1) Voltage Regulator ICs. Fea- ture built-in overload protection and thermal shutdown. Maximum input: 35VDC. 7805. 5V. #276-1770 1.19 7812. 12V. #276-1771 .... 1.19 (2) Low-Voltage Motor. Just the thing for science projects, robotics and solar power demos. Operates 1V2 to 3VDC. About W long. #273-223 99C (3) High-Speed 12VDC Motor. Up to 15,200 RPM, no load. About 2" long. #273-255 2,99 (4) "Ding -Dong" Chime. This IC and mini-speaker combo is ideal for a customer-entry alert or doorbell. Produces 80 dB sound pressure at 12 VDC. Operates 6 to 18 VDC. #273-071 8.99 (5) Surface-Mount Resistors. 200-piece assortment of 15 popular values. Rated Vs watt, 5%. #271-313 Set 4.99 Radio Shack Has 20 different project enclosures in stock! (6) Metal Project Cabinet. An at- tractive, easy-to-drill housing at a low price. 3 x 5V4 x 5 7 te" #270-253 6.79 (7) Project Labels. Four sheets Of rub-on letters, numerals and cali- brations. #270-201 2,99 (8) Power Supply Case. Vented 2'fex4 6 fex3Vi" molded case, #270-287 3.99 (9) to 15 DC Voltmeter. Panel- mount. #270-1754 7.95 (10) Box/Board Combo. Molded enclosure plus predrilled 2x3Ve" board, labels and more. #270-291 4.99 (11) Eight-Position Phono Jack Board. #274-370 1.39 (12) 1:1 Audio Transformer. 2: 600-90QO, #273-1374 3.59 (13) Three-Pin XLR Mike Plug. Metal body. #274-010 2.99 (14) Three- Pin XLR Mike Inline Socket. #274-011 2.99 (15) Three- Pin XLR Mike Panel Socket. #274-013 3.69 .Radio /hack AMERICA'S TECHNOLOGY STORE > c en c What's new in the fast-changing video industry. WIMHHIIME • Multimedia expands. Following the introduction of CDTV by Commodore (Radio-Elec- tronics, July 1991), several man- ufacturers are poised to introduce the standardized CD-I (Compact Disc-In- teractive) system this fall. Philips has announced that it will field Magnavox brand players in the U.S. in October, followed by a Philips brand unit a month later, and Sony, Panasonic, and others have indicated that they'll he in the market this year. The Magnavox CD-I players will carry a suggested list price of $1,400, but are expected to sell at ahout $1,000. They'll play standard CD audio discs, CD + Graphics (CD + G) discs, and the forthcoming Photo CD discs as well as multimedia CD-I discs. Discs will sell for around $20 to $60. Although initial discs will have animation at 15 frames per sec- ond, true full-motion video won't be available until some time in 1992. At that time, a simple plug-in adaptor (containing an MPU chip) will be of- fered to update players, but the origi- nal software will still be playable. When full-motion, full-screen video fi- nally is available, the five-inch CD-I disc may well replace the 12-inch laserdisc as the preferred carrier for recorded movies. The jury is still out on the various CD ROM multimedia products — at least with regard to the extravagant claims that they constitute the next hot consumer-electronics product or the successor to print publishing. • Closed captions. The FCC has accepted industry recommendations to implement the closed caption law with a relatively simple method of achieving captioning for the hearing impaired. Congress passed a law re- quiring caption reception capability in all sets 1 3 inches and larger manufac- tured or imported after June 30, 1993 (Radio-Electronics, May, 1991). An FIA task force recommended a system that uses on-screen graphics capabilities already employed by many TV set manufacturers. Some features that are now mandatory in the captioning rules will be made op- tional, and other features will be add- ed. Zenith has indicated that it will introduce closed-caption receivers well in advance of the deadline, with the first sets to appear this year at moderate prices, starting at around the $299 area. The captions, when generally adopted by the industry, are expected to be useful in areas other than assisting hard-of-hearing con- sumers, and could even lead to some kind of program identification sys- tem — such as display of the name of the program or episode — or even a possible automatic system that would permit viewers to program their VCR's by the name of the pro- gram to be recorded. • Widescreen VHS. JVC and Thomson Consumer Electronics (whose U.S. brands are RCA and GE) are working together on a com- patible system to record widescreen 16:9 images on standard VHS video recorders. According to JVC, the system would involve "identification signals" for automatic switching be- tween 16:9 and standard 4:3 aspect ratios. The system presumably would be a version of Super VHS recording. In Europe, widescreen enhanced-def- inition programming is already being transmitted by satellite, and in the U.S. Thomson and Philips are push- ing ACTV, an enhanced widescreen system, as an intermediate step be- fore HDTV. Thomson and Philips are consulting with other manufacturers on the proposed parameters, and JVC says it hopes to commercialize the system within a year. • Video compression. All of a sudden, everybody's talking about compression technology. From satel- lites to multimedia to HDTV, band- width compression is now regarded as the biggest breakthrough since color TV. A cable system in Queens, N.Y is now planning to offer 150 channels through a combination of compression and optical fiber. HBO will soon be offering a three-channel service to cable systems which can take advantage of compression to let viewers choose the starting time of the movies they want to watch. Sky- pix pay-TV service is squashing six channels into one on a satellite tran- sponder. Multimedia services, such as CD-I, are now talking about full- motion video on 5-inch optical discs through the use of compression. The computer has changed the nature of television. Soon there will no longer be a scarcity of spectrum because of the ability to squeeze many channels into one. • Big -screen sets gain. In spite of an 8% decline in total sales of color TV sets in the first three months of 1991 (as compared with the same period in 1990), direct -view sets 27- inches and up rose by 13%, and proj- ection set sales were up 15% — indi- cating a growing move to larger sets. Sets 27 inches and larger, including projection, rose to 16.8% of total sales from 12.2% in the similar year- earlier period. Direct-view sets with sizes 30 inches and larger jumped by 43.6%. • VCR popularity contest. What's the biggest-selling brand of camcorder? Why Sony, by a large margin. The latest survey by Television Digest newsletter gives Sony an 18% share of the camcorder market, followed by Panasonic with 14%, RCA with 13%, and Sears and JVC with 7.5% each. Runners-up to that top five were Sharp, Magnavox. GE. Hitachi, and Canon, in that order. The same survey which produced those rankings showed manufac- turers think 8mm wilt be 1991 's lead- ing format, accounting for 44% of camcorder sales, followed by full-size VHS with 40%, and VHS-C with 16%. In video decks, RCA was the un- disputed leader with 11% of the mar- ket, with Panasonic second at 8%, Emerson. Sharp and Magnavox 7% each, followed by JVC, Zenith, Sears, and Goldstar. The survey re- flects shares and rankings for the full- year of 1990. R-E 48HOHR ELENCO & HITACHI PRODUCTS 4 8hour SHIPP.NG AT DISCOUNT PRICES SHIPPiNG Hitachi RSO Series {Portable Real-lime Digital Storage Oscilloscopes) VC-6023 - 20 MHz. 20MS/S $99'mo" 50 MH z . 20 M S/s _ $ 1 ZOImo' (135/mo* J12S/ino # (200/mo* VC-6024 VC-6025 • 50MHz. 20MS/S. VC-6045 - 100MHz. 40MS/S LEASING AVAILABLE For all Hitachi Scopes - Coll lot detail t • Based on 24 months raoept V-1 150, VC-6045, VC- 61 45 [36 months} VC-614S • 100MHz, 100MS/S RSO's tram Hitachi feature roll mode, averaging, save memory, smoothing, interpolation, prstriggering, cursor measurements. These scopes enable more accurate, simplier observation of complex waveforms, in addition to such functions as hardcopy via a plotter interface and wavelorm Iransler via the RS-23ZC interface Enjoy Ihe comfort of analog and Ihe power to digital. 20MHz Elenco Oscilloscope $375 MO-1251 • Dual Trace Component Tester ■ 6' CRT ■ X-Y Operation • TV Sync « 2 P-l Probes Hitachi Portable Scopes DC lo 50MHz. 2-Charmef, DC offset func- tion, Alternate magnifier function V-S25 - CRT Readout. Cursor Meas. _ $1,025 V-523 - Delayed Sweep $995 V-522 - Basic Model _ S895 V-422 - 40MHz S79S V-223 - 20Mhz delayed sweep S695 V-21 2 - 20MHz $425 HITACHI COMPACT SERIES SCOPES This series provides many new functions such as CRT Readout, Cursor measurements (V-1 085/1 065'fi 65). Fre- quency Ctr (V-1 085). Sweaptime Autoranging, Delayed sweep and Tripper Lock using a 6 -inch CRT. You don't feel the compactness in terms of performance and operation. V-6S0 - 60MHz. Dual Trace V-665 - 60MHz, DT. w/cursor V-1 060 - 100MHz, Dual Trace V-1 065 ■ 100MHz, DT, wteursor_ V-1 065 - 100MHz, QT, w/cursor " V-1 1 00 A - too MH z. Quad Tracel V-1 150 - 150MHz. Quad Trace_ _S1,195 $1,345 1$ 1.42 5 $105/mo' I$125/mo' _$ 125/010' _$115/mo- Elenco 35MHz Dual Trace BHM^ $495 MO- 1252 * High luminance &' CRT ■ ImV Sensibly • 6KV Acceleration Voltage • 10ns Rise Tfme ■ X-Y Operation * Z Axi^ * Delayed Triggering Sweep « Includes 2 P-1 Probes All scopes include probes, schematics* operators manual and 3 year (2 yrs for Elenco scopes] world wkre warranty on parts & labor. Many accessories available for all Hitachi scopes. Call or write for complete specifications on these and many other fine oscilloscopes. FREE DMM with purchase of ANY SCOPE SCOPE PROBES P-l «MHz, Ix, lOx $19.95 P-2 100MHz, )x, lOx $23.95 I*.* *i?D Beckman TEST EQUIPMENT All Models Available Call for special price Digital Capacitance Meter CM-1550B $58.95 9 Ranges 1p!-20. would .5% basic accy. Zero contra! w/ Cass Big 1 ' Display Digital LCR Meter LC-1801 $125 Measures: Coils 1UH-200H Gaps -lpl-200ul Res .01-20M Big 1" Display Multimeter with Capacitance 6V Transistor Tester $55 CM- 15 DOB Roads VoNs, Ohms Cunent, Capacitors, Transistors and Diodes I with case FLUKE MULTIMETERS All Models Available Call for special ptlce Quad Power Supply XP-580 ,$59.95 2 -20V @ 2A 12V @IA 5V@3A ■5V .5A Fully regulated and short circuit protected Triple Power Supply XP-620 Assembled $65 Kit $45 2to15V@1A. -2lo-f5V@1A (or*lo30V@1A) and 5V @ 3A All Ihe desired leaiures lor doing experiments. Features short circuil protection, all supplies AM/FM Transistor Radio Kit with Training Course Model AWFM1 OB $26.95 1 4 Transistors * 5 Diodes Makes a great school project True RMS 4 1/2 Digit Multimeter M-7000 $135 .05% DC Accuracy ,1% Resistance with Fraq. Counter and Deluxe Case GF-8016 Function Generator with Freq. Counter $249 Sine, Square. Triangle Pulse, Ramp. .2 to 2MHz Freq Counler .1 - 10MH: GF-B01 5 without Freq. Meter $ 179 Function Generator "__ „ ;• ■■ Blox liT**| $28.95 Provides sine, triangle, square wave from 1 Hi to 1 MHz AM or FM capability Learn to Build and Program Computers with this Kit Includes: All Parts, Assembly and Lesson Manual Model MM-SO00 Wide Band Signal Generators $129.00 Starting from scratch you build a complete system. Our f*cro-Master irainor loaches you to wrtta Into RAfcAs, ROW; a/id run a 60S 5 microprocessor, which u$o$ sJrTpjlar machine language as ISM PC. Robotics Kit for above c a c to CIRCLE 109 ON FREE INFORMATION CARD ASK RE Write to Ask R-E. Radio-Electronics, 500-B Bi-County Blvd., Farmingdale, NY 11735 to o z o tr - o LU I LU o Q < SINGLE-CHANNEL FILTER Is it possible to buy a filter that would attenuate only one station (channel 58), by about 6 dB? The channel is causing ghosting on neighboring channel 56. 1 live in a fringe area and channel 58 is many miles closer than channel 56. I have several TV sets and only my new Heathkit TV is suffer- ing from this problem. — R. Law, Wetlfleet, MA I've never had a problem like this so I can't give you a ready-to-wear an- swer to the problem. There are some things about your predicament that surprise me however, and t have a few suggestions about what you can do. The first thing that struck me is that you're getting channel crosstalk and interference on only one TV — and a new one at that. If this had been a problem on every TV in your house I would have called it an unavoidable problem but, since it happens on only one TV, it's logical to suspect the tuner in that TV. I called Heathkit to ask them about your problem and everyone that I spoke to went on at length about the quality of their tuners and was sur- prised that you were having that prob- lem. You didn't include signal- strength readings with your letter- — if you have such readings you can con- tact Heathkit again and they'll tell you whether the tuner in your TV is per- forming up to spec. If you don't want to do that, or if you don't have any access to a signal- strength meter, you can accept the crosstalk as a feature (?) of your TV and, as you asked in your letter, do something to attenuate the chan- nel-58 signal before it gets to your TV. There are several companies around that specialize in making traps to remove either individual channels or a range of channels and you'll find that a bunch of them advertise in Ra- dio-Electronics. I called Star Cir- cuits of Las Vegas (1 -800-433-631 9), a Radio-Electronics advertiser who makes channel traps. The peo- ple there were extremely helpful and, when I explained the problem, they were sure they could come up with something that would do the job. They sell their traps for about twen- ty five bucks and, even though I still think the problem is in your TV's tuner, it's probably a lot less of a has- sle to add an attenuator to the anten- na input than it is to start fooling around with the circuitry in your TV. MOTORCYCLE REBUILD I'm rebuilding a 1970's era motorcycle and am stuck on how to go about setting up a power- management system. I have an alternator and am now looking for a voltage regulator. In the best of all possible worlds I would have a redundant system so that if one fails I could switch over to the other one. Can you help? — G. Perry, Barrington, NH Every once in while a letter comes in that I can take a particular pleasure in answering. You couldn't have sent your letter to a better person — I own a 1968 Jaguar and recently finished rebuilding a 1968 Triumph Bonneville. For my money, that's the best bike ever made. I had a similar problem to yours when it came to the electrical sys- tem. All the original stuff was made by Lucas (why do the British drink warm beer? — because they use Lucas re- frigerators), and I had no desire to use the original parts. And when I found out that the original Lucas reg- ulator cost eighty-five bucks. I was doubly sure I wanted to do something of my own. After all, a voltage reg- ulator is an electronic thing and I know about that stuff. The circuit shown in Fig. 1 is the voltage regulator I've been using in both my car and the bike. It's been working in my car for about eight years and I ve never had any trouble with it. As you can see, it uses stan- dard parts that can be gotten almost anywhere. Before you go out and get every- thing you need to build the circuit there are some things you have to know about an alternator. Different bike and car manufacturers use dif- ferent techniques to handle all the alternator connections and you have to know how your bike is set up be- fore you get started. Since you're re- building everything anyway, it may be possible to set things up in a manner different than what was done origi- nally by the manufacturer. Even though an alternator pro- duces three-phase AC, as far as the external world is concerned it's a DC machine. There are usually six diodes on two D-ring heat sinks that rectify the AC before it leaves the alternator. What sets an alternator apart from a generator is not only the need to rec- tify the output of the windings (a gen- erator will produce DC directly), but also the presence of the field coil. Alternators have a working sim- FIG. 1— THIS VOLTAGE REGULATOR can be used with cars and motorcycles. It uses standard parts that are easily and inexpensively available. Learn to Use Your Computer's Full Potential. - r^^ New Career Course from •* CIE! 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And it's a course designed to fit around your lifestyle and commit- ments today, so you can be assured of professional successes and financial gains tomorrow. Please, do yourself a favor and send the attached card or fill out and mail the coupon below for more information about CIE's Computer Operation and Programming course. Do It Today! Computer not included with course O YES! I want to get started. Send me my CIE school catalog including details about the Associate Degree program (for your convenience, CIE will have a representative contact you - there is no obligation). Print Name Address City Apt. State . .Zip, Age Area Code/Phone No„ Check box for G.I. Bulletin on Educational Benefits O Veteran CLEVELAND INSTITUTE OF ELECTRONICS 1776 East UthStrcei Cleveland, Ohio 44114 (216)781-9400 □ Active Duty (fir) A school of thousands A class of one. Since J 934. AE21 > c a c Cn 11 ilarity to transformers. You can think of the main three-phase windings as the secondary and the field windings as the primary. Like a transformer the more voltage you have across the pri- mary, the more you'll get out of the secondary. A voltage regulator for an alternator is essentially a controller that monitors the system voltage and tries to keep it at a certain level by adjusting the amount of current (and hence the voltage) present in the field windings. Given all that, a standard alternator has four terminals that have to be connected to the electrical system. The secondary windings (the main al- ternator windings) are usually sent to power and ground, but the connec- tions made to the field windings vary with the manufacturer of the car or bike. The field terminals can be treated in one of the following ways: Both field terminals can be brought out of the alternator and left floating for you to connect any way you want, one side can be grounded inside the alter- nator (called a grounded field), or one side can be tied to the DC positive inside the alternator (called a pulled- up field). The schematic in Fig. 1 is designed to work with a system that has a grounded field. Since you've been fooling around with your own de- signs, you should be able to easily modify it to work with a pulled-up field if that's the situation in your bike. Basically, the voltage regulator monitors the system voltage and controls the field current by modulat- ing Q2 and Q3 (they're set up as a Darlington pair because I found it dif- ficult to get the Darlington I wanted to use). The output is being modulated and the transistors are being run sat- urated (used as a switch) because they run a lot cooler that way. The three external connections are ■fV (connected to the battery), the field (connected to the free end of the field coil), and ground (connected to system ground). Let me repeat that this regulator is designed to work in a system that has a negative ground and in which one side of the field windings is grounded as well. If your system is set up for a pulled up field and you use this circuit, you'll blowup the regulator and possibly destroy some other electrical stuff in the bike as well. As I said, I've been using this reg- ulator in both my car and bike without any problem at all. I included LED1 in the circuit because it gives me a visu- al indication that the charging system (or at least the regulator) is working. You can use the potentiometer to ad- just the knee of the regulator. The setting here will determine what the steady-state voltage of the regulator will be. Moving it to one end will effectively turn off the charging system (although why you'd want to do that is beyond me), and turning it to the other extreme will cause the alternator to put out a lot of juice. That can be handy for those times when your battery is either in need of a charge or you're putting a heavy cur- rent demand on the electrical system (lights on in stop-and-go traffic during a heat wave and rainstorm). If you're using the regulator in a car, you can mount the potentiometer and LED in- side the car so you can monitor its action and make adjustments while you're driving. The regulator should work well regardless of the con- struction method you use. I designed a PC board for it and, if you're inter- ested, drop me a line and I'll send you a copy of the foil pattern. Best of luck from a fellow biker. 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LETTERS Write to Letters, Radio-Electronics, 500-B BhCounty Blvd., Farmingdale, NY V 735 CO o o LU o a Accredited by the Accrediting Commission of the National Home Study Council GRANTHAM College of Engineering Grantham College Road Slidell, LA 70460 TONER CARTRIDGE OMISSION We were shocked and disap- pointed that Chenesko Products, Inc. was not mentioned by Don Lancaster in Hardware Hackerin the May issue of Radio-Electronics. The compa- ny has been involved with toner-car- tridge recharge for five years and sells to both end users and dealers engaged in the recharge business. Our catalog has been out for more than three years, and we carry the most extensive line of products in the industry. EDWARD W. GRENZIG. PRESIDENT CHENESKO PRODUCTS, INC. 62 North Coleman Road Centereach. NY 11720 BRING BACK THE TUBES As a working audio professional, after reading his recent Audio Update columns, I think it's fairly obvious that Larry Klein simply doesn't know what he's talking about. He and the other "scientific audio authorities" such as Bob Carver and the crew at Mcintosh are about as scientific as pro wrestlers. I work mainly with mid western pop, country, and jazz recording artists. While few of them are "audiophiles" in the classic sense, very few are not capable of hearing the difference, and preferring older, simpler, and most often tube gear over modern stuff sporting superior measurements. Tube condenser microphones such as Neumanns, tube compressors (such as those from Fairchild and Pultec), and most especially, tube guitar amplifiers and effects are very popular and their value is increasing every day. Various companies are now making new tube studio hard- ware, which, while often expensive, seems to be selling quite well. Recording-studio owners are not "tweeks" and faddists, but hard- nosed and often intrinsically cheap fellows who buy gear strictly on the basis of the results generated. Pro- ducers and artists can hear the dif- ference, and among those who care a great deal about their sound, a good deal of tube equipment is the rule, not the exception, especially for miking vocals and for guitars. The bottom line is that the current battery of audio tests are not even close to sufficient for "objective" analysis of what is going on inside audio amplification and processing gear compared to the limits of what even the rudimentarily trained human ear can discern — when its owner's conscious mind has not stopped it from doing so. The "subjectivist" crowd of audio reviewers are only at- tempting to fill a void in the knowl- edge accrued on the subject, however successfully, and if Mr. Klein and friends cannot do better, I sug- gest they leave it to those who can. To close, I can do no better than to paraphrase L.A. Rollins famous lex- icon: "Spec worship; Sense of life experienced by (audio) objectivists and other breeds of dog." RICHARD CARYSFORTH Lenexa, KS EASIER INDICATOR I would like to suggest a simpler remedy to the problem posed by T Waller in Ask R-E in the May issue of Radio-Electronics. Mr. Waller asked for a visible indication that he is using the print-screen function of his IBM compatible. Your response points to a complicated hardware so- lution that would not really solve the problem. As I see it. Mr Waller wants to know when a screen print is in progress, and not just that the print- screen key has been pressed on the keyboard, A short software routine would pro- vide a simple solution to the problem. The print-screen key press could be determined by intercepting either the BIOS keyboard character fetch rou- tine or, better yet, the actual print- screen routine itself. For example, he could change the BIOS print-screen routine vector to point to his own custom patch. The first thing the patch does is to turn on some kind of indicator that shows a screen print is in progress. When that subroutine re- turns control to his patch, he can sim- 14 Now, You Can Eavesdrop On The World. Introducing the new Drake R8 Communications Receiver. It's world class, world band radio, made■■■ . 1 WCSt 1 fHWO 'T 51 " 7 s " 7=^ ■ ---S I has been setting the standards in electronic communications. . .and then raising them. Today, there's no better shortwave receiver than the Drake R8. Out-Of-This-World Performance. The new Drake R8 has more standard features than other shortwave radios. You get wide frequency range (100 KHz to 30,000 KHz), coverage of all world and local bands, and excellent dynamic range. But you also get important features you won't find on receivers costing hundreds of dollars more. A multi-voltage power supply. Pre-amp and attenuator. Five filter bandwidths and synchronous detector. Dual mode noise blanker and passband offset. Non-volatile 100 channel memory. All designed to give you the best reception with the least distortion. Down-To-Earth Design. 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I don't know anyone who uses the scroll-lock indicator, so it is probably available. All that Mr. Waller must do is write the scroll lock on character to the keyboard through the proper BIOS call when his patch routine starts. At the end of the rou- tine, he can write out the scroll-lock- off character. An AT or better is re- quired because a PC or XT cannot write back to the keyboard. If the ma- chine is a PC or XT, an external LED indicator can be wired into an unused serial or parallel port pin. I hope this is a more workable solu- tion to the proposed problem. JEFF SCHMOYER Colorado Springs, CO MIND OVER MONEY I read with interest Alex Funk's let- ter in the April issue questioning the "idiocy" of Charles Colby's article, "Build a Macintosh-Compatible Computer" (Radio-Electronics, January 1991). I used that article to build the SE-30, and there are a cou- ple of points I'd like to make. If all you want is a computer, then you are probably better off buying ei- ther a new one or a good used one form a friend or a reputable dealer. The real purpose in building your own system is to learn about its design and construction. Half the articles in Radio-Electronics are about building devices that are almost al- ways commercially available, al- though at generally higher costs. But buying the finished product defeats the whole purpose of having elec- tronics as a hobby. The idea of charg- ing yourself 10 hours of construction time, as Mr. Funk does in his cost assessment, makes no sense to the hobbyist. Mr. Funk also includes in his expen- ditures for building a Mac $50 for a motherboard and $50 for a monitor. He apparently is talking about the Mac 128K, the least powerful of the Macs. His conclusion is accurate: It just isn't cost effective to build such a low-end system. For the same amount of labor — or even less with the help of the article and Colby's video— you can build an SE-30, a far greater value for your money. The cost of construction falls into the $2200-$2400 range, compared to the $4500 retail cost of the same Mac. While that kind of money might be out of reach for many hobbyists, it still demonstrates the potential in cost savings. I suspect, however, that in Mr. Funk's case, the problem has less to do with money than with one's attitude. Finally, I would like to say that I found Mr. Colby's article very enjoya- ble, I had the opportunity to speak with him by phone during the con- struction of my Mac, and both he and his company were very helpful with their advice. KEVIN HOLLEY Reston, VA IBM-PC PROPONENT I say "Right on!" to Jeff Holtzman in his response to Raymond Cheng (Letters, Radio-Electronics, April 1991). My first computer was a Texas In- struments Tl 99/4A. There were Tl 99/4A zealots at that time. The com- puter served its purpose: It helped my family to better understand com- puters and to learn a bit about BASIC and other programming. It was treat- ed as an educational tool, but was little more than a toy when it came to useful applications. Several years later we bought our first MS-DOS personal computer. We delayed this purchase until there was some hint of standardization, competitive marketplace, and long- term usefulness due to its com- patibility at work and at home. The entry of IBM clones provided that confidence. In less than three years, we purchased four MS-DOS com- puters. The second and third were for two children in college (engineering and business). The fourth was to up- grade our own computer and to pass on the first one to our oldest son. Radio-Electronics has gauged its readership well. In my opinion, Ra- dio-Electronics covers items that are of interest to the vast majority of its readers. I like the computer arti- cles, but my primary interest is in new technology and explanations of how devices work. I seldom build anything anymore. However, articles on con- struction usually describe how the equipment functions, and why. Keep up the good work. T. LAMAR MOORE Alexandria, VA R-E Why take chances in today's job market? Graduate as a fully trained electronics professional. To get ahead and stay ahead in today's economy, you need the electronics training CIE has been providing its 150,000-plus successful graduates with for nearly 60 years. Meet the Electronics Specialists. When you pick an electronics school, you're getting ready to invest time and money. And your whole future depends on the education you receive in return. That's why it makes so much sense to go with number one... with the specialists... with CIE! There's no such thing as a bargain education. 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People who have: No previous electronics knowledge, but do have an interest in it; Some basic knowledge or experience in electronics; In-depth working experience or prior training in electronics. At CIE you start where you fit and feel comfortable where you start, then go on from there to your Diploma, Associate Degree and career! Today is the day. Send now. Fill in and return the postage-paid card attached. If some ambitious person has already removed it, cut out and mail the coupon below. You'll get a FREE CIE school catalog, plus complete informa- tion on independent home study. Mail in the coupon below or, if you prefer, call toll-free 1-800-321-2155 (in Ohio, 1-800-623-9109). □ YES I I want to get started. Send me my CIE school catalog including details about the Associate Degree program, (For your convenience t CIE will have a representative contact you — there is no obligation,) Print Name Address City . Age A tea Code/Phone Net- Apt. State -) — .Zip- Check box for G.I. Bulletin on Educational Benefits O Veteran □ Active Duty 'an INSTITUTE OF ELECTRONICS, INC. ) 776 EbsI 17th Slmet ' Cleveland. Ohio 44114 ' (216) 781-9400 -' ~Mltl±y . A school of thousands. { ■"S'T £ A class of one. %■**■!/ Since 1934. AE20 > c Q c 17 Troubleshooting & Repairing VCRs * Radio-Electronics® Special — Choose Electronics Hobbyists . . . SELECT 5 BOOKS for $495 only when you join the Electronics Book Club SM 261 3F 517.95 £370 £32.35 Counls as 2 3157P $16.95 2925P 39-9$ Battery- powered TwoIC Projects 3155 517.95 I' HOOOKDUdf . ELECTRONIC CIRCUITS ' 34*4 S39.9S CounlG As 2 2TQ7P 517.9S 1939 560 00 Count* aa 3 2SB0P $14.3$ ACiDC . EU-fTIHriTY & SLfcCTRONICS MADE EASY SECOND EDITION 3285 S25.95 Counls H 2 3632 Slfl.SS Liif.imist.vic DGCrURGE PfiOTECnON 23 i^i 3- 3312 523.95 Grcal Sound Stiwtt Spcakrf Manual ffil 3550 S34-9S Counts ss 2 2965P 51 4.9S 327-1 J25.95 Counts ss 2 3329 $29.95 Counts ,15 2 .lUEOf' 514.95 UAH llHIIIMTsUflKJl 9299 33.5.90 Counts AS 2 TRTKQ11PMEST 3475 $27.95 Counts ss 2 25 OOP SI 6. 95 3465 527.95 Counts as 2 All books are hardcover unless number is [allowed by 3 "P" for paperback, (Publishers' Prices Shown) A shipping/haAdiir.g charge and sales tax win be added (0 all orders. to 199:1 Electronics Book Club. Bhjs Ridge Summit, PA 17294-OSitQ O by Gang back Publications, Inc. _^^_^^_ 2JS.7P Stfl.95 MOV J- EXECTHOMl s FIX-IT BOOK INK STRIAI. 2883 P HB.95 3321P 516.95 3343 529.95 3D31P 317.95 Your most complete source for electronics books for over 25 years. 29B0P 519,95 303*P S13-95 HOW THE CLUBS BIG SAVINGS: In addition to this introductory offer, you keep saving substantially with members' prices of up to 60% off the publishers' prices. BONUS BOOKS: Starting imme- diately, you will be eligible for our Bonus Book Plan, with savings of up to 80% off publishers' prices. SHOP-AT-HOME CONVENIENCE: Every S4 weeks, you will receive the Book Club News, describing the Main Selections and Alternates, as well as bonus offers and special sales, with scores of titles to choose from. AUTOMATIC ORDER: If you want the Main Selection, do nothing and it will be sent to you auto- matically. If you prefer another 18 the club that suits your needs . . . Electronics Engineers . . . Take any 3 PROFESSIONAL BOOKS *° r |y $ 9~ when you join the ELECTRONICS ENGINEERS' BOOK CLUB COWdJWMTIIJNS RECEIVERS re menus C J 151 en a ■ 053970-1 56 1.95 Counls as 2 3117 S3B 95 9243P SI 2.95 029975-9 599.50 Counts as 3 3099 S44.50 Counts as 2 Your source for quality, affordable, and timely authoritative engineering books. 9255 $97.50 Counts as 3 WORK FOR YOU! selection, or no book at all, simply indicate your choice on the reply form provided. You will have at least 10 days to decide. As a member, you agree to purchase at least 3 books within the next 2 years and may resign at any time thereafter. Books purchased for professional purposes may be a tax-deductible expense. IRONCLAD NO-RISK GUARANTEE: If not satisfied with your books, return them within 10 days without obligation! EXCEPTIONAL QUALITY: All books are quality editions from the leading publishers and experts in both the electronics and engineer- ing fields, especially selected by our Editorial Board for timeliness and accuracy to members. 3198 552.00 Counts as 2 3313 522.95 057537-1 139.95 Counts as 2 9305 S59.50 Counts as 2 THE PROGRAMMABLE LOGIC DEVICE HANDBOOK 3140 S49.95 Counts sa 2 296 2 P SI 7. 95 055443-3 157.50 Counts ss 2 m ELECTRONIC CIRCUITS V 313SH £60 -00 Counts as 3 ELECTRONIC COMMUNICATIONS ~*^m PRINTED CIRCUITS DESIGN Foaturtng Computer' Aided Technologic; GERALD L £1 HI 11*5 3365 S3 4. 95 10016 S39.$S Counts as 2. 31 M S75.00 Counli 9* 3 033559*1 S27.9S PRINTED CIRCUITS HAHDBOOK 3531 $26.95 9340 S44.95 Counts ss 2 G29735-X S79.50 Counts ss 3 3151 S42.95 012609-7 $04.95 Counts ss 2 CMOS SYSTEMS 10037 S44.95 All books ato hatdcover unless number Is rultowed by a "P" lor paperback. (Publishers' Prices Shown) A shlpplngjhsndling charge and salBS la* will be added in all orders. ©1991 Electronics Engineers' Book Club, Blue Ridge Summit, PA 17294-0860 > c o C a c CD 23 NEW PRODUCTS Use the Free Information Card for more details on these products. PC-BASED LOGIC ANA- LYZER. NCI's PA485 PC- based logic analyzer has been upgraded in two ways: It now operates at 50-MHz on 48 channels in either state or timing modes, and it now comes with Windows 3.0-com- patible software. The up- graded board offers 4K bits per channel of memory, 16 trigger words. 16-level trig- ger sequence, selective storage on each trigger level, and numerous dis- assemblers for various mi- croprocessors. The software allows the user to simultaneously view and scroll through a numerical window, a wave- form window, and an as- sembly window. The soft- ware also lets the user cut and paste timing diagrams Cor any other window) to a word processor for docu- mentation of results, and run the analyzer in one win- dow while working on an- other application in another window. Other software features include an indexed CIRCLE 16 ON FREE INFORMATION CARD on-line help system, a com- mon edit box for multiple windows, and the ability to simultaneously view up to 25 channels in the timing diagram with a VGA monitor or more than 40 channels when used with even higher resolution monitors. The complete PA485 system, including the board, pod, and software, costs $1895.— NCI. 6438 University Drive. Hunt- sville, AL 35806; Phone; 205-837-6667. Fax: 205-837-5221. MODULAR INDUSTRIAL PC. Rapid Systems PCX! CPC Extended for Industry) is a modular, industrial per- sonal computer based on a 6-, 7-, or 13-slot passive backplane. The PCXI in- cludes a 7'/2-inch, color Sony Trinitron monitor inte- grated within a table-top (PXW12/1490) or rack- mount (.PX1010/1490) g chassis. Applications in- z elude production tests, § data acquisition and con- p trot, factory automation, networks, and worksta- tions. The rack- mount ver- sion, with a 6-slot passive backplane, VGA monitor CIRCLE 17 ON FREE INFORMATION CARD with 720x480 resolution, 0.26-mm dot pitch, and RGB analog input, makes an ideal test platform. Vari- ous single-board comput- ers, From 286 to 486, are available, completely en- closed in metal modules to shield from EMI/RFI emis- sions. The PCXI features frond-end cabling and con- nectors and accommo- dates all commercially available PC boards. The PCXI modular indus- trial PC costs $3095.— Rapid Systems Inc., 433 North 34th Street, Seattle. WA 98103; Phone: 206-547-8311; Fax: 206-548-0322. TEN-IN-ONE INSTRU- MENT. Boasting the ver- satility of a complete line of instruments in one 3 3 /i-dig- it, 4000-count multimeter case, Global Specialties' Protometer 4000 handheld instrument system fea- tures ten test instruments capable of performing 35 measurement functions. The Protometer 4000 com- bines a DC voltmeter, AC voltmeter, ohmmeter. am- meter, diode/LED tester, transistor tester, capaci- tance tester, autoranging frequency counter, logic probe, and continuity test- er. Special heat-resistant components extend the current-measuring range to 20 amps AC/DC. The one unit can be used to check every electronic compo- nent — capacitors, tran- sistors, diodes, resistors, and LED's — eliminating the need for a separate com- ponent tester. Standard features include a large LCD readout, 4000-count accuracy, peak hold, and a unique high-voltage warn- ing indicator. The Pro- tometer 4000's Its rugged construction and drop-re- sistant case make it well- suited for field-service and industrial-maintenance. The Protometer 4000 ten-in-one test instrument costs $139.95.— Global Specialties, 70 Fulton Terrace, New Haven. CT 06512; Phone: 203-624-3103; Fax: 203-468-0060. CIRCLE 18 ON FREE INFORMATION CARD 24 LOW-NOISE POWER SUPPLIES. Two benchtop DC power supplies from Hewlett-Packard offer high performance plus ripple and noise less than 200 mV RMS. The models HP E36I0A (pictured) and HP E36I1A feature dual-range outputs and CV/CC oper- ation with automatic mode crossover. The CV mode is for devices requiring con- stant voltage and the CC mode is for those requiring a constant current. The E36WAs Range 1 is 8 volts/3 amps and Range 2 is 15 volts/2 amps; the E3611A-S Range 1 is 20 volts/1.5 amps and Range 2 is 35 volts/0.85 amps. For user convenience, each of the 30-watt power supplies has separate dig- ital displays for voltage and current readout, a CC-set button for setting the cur- rent level of the supply CIRCLE 19 ON FREE INFORMATION CARD without having to short the output, and mode-indicator LED's to show whether the unit is in CV or CC mode. The E3610A and E36 HA low-noise DC power sup- plies are list priced at $300 each, — Hewlett-Pack- ard Company. Inquiries. 19310 Pruneridge Avenue, Cupertino, CA 95014; Phone: 1-800-752-0900. TELECOMMUNICA- TIONS WIRING TEST- ERS. According to Paladin Corporation, their Patch Check\s the first hand-held instrument that can specifi- cally identify the exact con- nection point of two con- nections at each end of a modular cord assembly. Designed to check tele- CIRCLE 20 ON FREE INFORMATION CARD phone (RJ11) and comput- er data link (RJ45) wiring, the Patch Check identifies open, shorted, and cross- connected wires on a clear LED display. It also verifies the correct wiring config- uration of unshielded twist- ed pair in the 10BASE-T baseband medium. The in- strument is easy to use: the user simply presses a button to review a sequen- tial comparison of the wire position and continuity of the modular plugs at each end of the cable. The Patch Check tele- communications wiring tester, complete with in- stalled battery and one- year warranty, has a list price of $49,95— Pal- adin Corporation, 3543 Old Conejo Road, Suite 102. Newbury Park, CA 91320; Phone: 805-499-0318. STANDARDS-CON- VERTER VCR. New tech- nology enables the 50/60 Image Translator VCR from Instant Replay to produce 525-line, 60-Hz NTSC sig- nals from 625-line, 50-Hz PAL/SECAM, allowing the user to play PAL or SECAM tapes on Ameri- can CNTSC) TV's or monitors. The 50/60 is a true standards converter CABLE - TV SIGNAL REMOVERS ■FOR ELIMINATION OF SEVERE INTERFERENCE ■FOR "CENSORING - OF ADULT BROADCASTS • ATTENUATION - « dB TYPICAL • BANDWIDTH - 4 MHi AT 5 dB POINTS • INSERTION LOSS - 2 dB uOOEl TUNING RANGE FOR CHANNELS PA9SBAMD price a,<,ppiKG !3H S0-6-S UH2 2.3 [m 6 mtltr bim) 50-350 MHl 130 NO SHIPPING or C.O.D. CHARGES 45 FM e$.10$MH; ■'■ 5 i ■:.' in, FM| 50.300 UHl S3 3 1417 1Z0-14* MH: 14(A| 1S[B} 16(C) 17(D1 W-400 UHl 130 IB22 141174 Mhz 1»[E] 19(F] 20(G) J1|H)!2(I( 50.400 V i: $30 713 174.21 E MHl 7 S 9.10 11.12.13 50-400 MH: S30 3 for $75 - 10 for $200 - mix or match CALL TOLL FREE FOR C.O.D ORSENDCHECKTOORDER FAST DELIVERY 30 D A Y MON EY B AC K GU AR ANT E E {3 F !LTE R LIM IT) Star Circuits P. 0. Box 94917 Las Vegas, NV 89193-4917 1-800-433-6319 CRAMOLIN DeOxidizer IMPROVES CONDUCTIVITY DEOXIDIZES * CLEANS • PRESERVES • LUBRICATES FoiAII Metots, Including Gold! CRAMQUN 8 DeOxidizer improves conductivity by dis- solving oxides thnt form on metal connector ond cor> toct surfaces, eliminating unwonted resistance ttiot impedes electrical performance. CRAMQLIN" is on active ingredient that does not rely on solvents for perform once. Due to the excel' lent migrotion properties, CRAMOLIN® toots me entire melol surface ond protects it from future oxidation. CRAMOLIN 8 continues to tie the most effective ond economical product for improving ond mointoining electrical component reliability. FOR MANUFACTURE MAIHTENANG AND SIRVia OF: • Switches S Relays * Coble Connectors £ Adaptors • Edge Connectors • Teiminol Strips • Plugs 8 Sockets • Gold Pinter! Connectors • Potentiometers • Battery Centals USED BY THOSE WHO DEMAND THE BEST: • Bell £ Howell • Capitol Records * Dolby Laboratories • Hewlett Pockord • John Fluke Mfg. • Mcintosh Lobs • MCf (Sony) • Motorola • NASA • Nokorrichi • RCA • Swittficmft • ond Mony More. P.O-BoxJ EsairddQ,tt9203M479 (619)743-7143 mtwmm I LABORATORIES, INC. 'EnvnonmtnltHy Conscious' CIRCLE 50 ON FREE INFORMATION CARD > C C in 25 o z o DC I- O LU _l 111 6 < a: CIRCLE 21 ON FREE INFORMATION CARD and full-featured VCR with tuner, timer, and wireless remote contra!. No prob- lems with picture rolling are created in the conversion process, and no vertical hold control is required. The converted signal is rec- ordable. The standard NTSC signal and the con- verted output are available as composite video, RF, and with S-VHS outputs in S-VHS models. The new conversion technology is compatible with previous and current Image Trans- lator products, and owners of earlier Image Translator VCR's can have their units retrofitted with the 50/60 digital frame standards module to allow complete compatibility with all TV's, monitors, and projection systems, and for stan- dards-conversion pur- poses. Prices for the 50/60 Im- age Translator VCR's begin at $995 —Instant Re- play, 2601 South Bay- shore Drive. Suite 1050, Coconut Grove. FL 33133; Phone: 305-854-8777; Fax: 305-858-9053. SCANNER ANTENNA. Designed to provide great reception at a low price — and be rugged enough to withstand wind and weather — the Super Scan- ner Stick from Electron Processing receives all scanner frequencies be- tween 25 and 1200 MHz. Its unique internal multi- pole construction allows the compact antenna to cover such a wide range of frequencies, and an inter- nal 15-dB "Signal Inten- sifier" amplifier ensures strong signals, even from distant stations. Com- pletely encased in a PVC tube, the Super Scanner Stick withstands weather conditions that routinely destroy other scanner an- tennas. The 35-inch-long antenna comes completely assembled with mounting clamps for masts up to 2- inches in diameter, so in- stallation is easy. To con- nect the antenna to its 1 1 5- VAC power unit, a 25-foot CIRCLE 22 ON FREE INFORMATION CARD coaxial cable is included; longer lengths are avail- able. The power unit con- nects to a scanner via a supplied jumper cable. The Super Scanner Sf/c/ccosts$80;a12-VDC version is available for $84 —Electron Pro- cessing, Inc., P.O. Box 68, Cedar, Ml 49621; Phone: 616-228-7020. IC MAILERS. iTOI Enter- prises offers a simple, low- tech solution to a high-tech problem — how to safely ship delicate electronic components. Designed to physically and electrically protect IC chip sets and cir- cuit components during shipping and transport, the ChipShip family of mailers features double-folded cor- rugated wrap to prevent crushing, conductive foam inserts to prevent ESD CIRCLE 23 ON FREE INFORMATION CARD damage, and bonded cushions to reduce vibra- tion and shock damage. Foil-lined versions also of- fer protection from EMI/ RFI radiation. ChipShip is a real time saver, replacing the assorted spare tubes, conductive foam, bubble wrap, anti-static foam, foil wrap, and boxes with a sin- gle, ready-to-go, pre- assembled package. The containers are available in two sizes C5!/2X 3 x 1 '/ 2 inches and 6V2XAV2XV/2 inches), in foil-lined and un- lined versions, and can hold various quantities of 8-. 16-. 28-, or 40-pin DIP ICs. ChipShip packages are priced from $2.95 to $4.95 each, and are shipped in cartons of 10. — iTOI En- terprises, P.O. Box 59, Newton Highlands, MA 02161; Phone: 617-332-1010. UV EPROM ERASER. According to Logical De- vices, their Palm-Erase is the industry's smallest UV EPROM eraser. It is par- ticularly designed for field service and engineering applications where space is at a premium. The Palm- Erase can erase EPROM 's in less than three minutes. It incorporates a small tray that can accommodate a single 24-, 28-, 32-, or 40- pin EPROM at a time. The device is packaged in a 4x 2 x 2-inch gray-and- white plastic enclosure and operates on 110-VAC input power. The bulb intensity is 1.7 |i,W/cm 2 , and the aver- age bulb lifetime is rated at 3000 hours. The Palm-Erase UV EPROM eraser costs $49.95— Logical De- vices, Inc.. 1201 NW 65th Place, Fort Lauder- dale, FL 33309; Phone: 1-800-EE1-PROM; Fax: 305-974-8531. PC-COMPATIBLE CIR- CUIT BREADBOARD. With a unique bus-grid de- sign that allows easy ac- cess to power and ground hook-up points. Radio Shack's Archer Experi- menter's Plug-In Card CCat. No. 276-1598) can be used CIRCLE 24 ON FREE INFORMATION CARD CIRCLE 25 ON FREE INFORMATION CARD by technicians, students, and hobbyists to bread- board digital and analog cir- cuits. The board is made of sturdy epoxy-glass-com- posite material and has a card-edge that is compati- ble with XT-style micro- computer expansion bus connectors. In addition, the Experimenter's Plug-In Card has an input/output port designed to hold a right-angle DB25 con- nector. Board holes are plated-thru For electrical continuity and measure 0.042-inches spaced 0.100-inches on centers. The board itself measures SVsXlO'/ieX'/ie inches. The Archer Experi- menter's Plug-In Card sells 26 Now with NRI's new training you can enjoy the rewards of a career in computer programming A top-paying career in computer programming is no longer out of your reach. Now you can get the practical training and experience you need to succeed in this top-growth field. It's training that gives you real- world programming skills in four of today's hottest computer languages: BASIC, Pascal, C, and COBOL. Hands-on training that includes a powerful IBM AT-compatible computer, modem, and program- ming software you train with and keep. Comprehensive, at-home training that gives you the competitive edge to succeed in one of today's leading industries. The kind of experience-based training only NR1 can provide. As a trained computer programmer of the '90s, you can enjoy long-term career success. In fact, ihe Bureau of Labor Statistics forecasts that during the next 10 years job opportunities will increase by 71.7 percent for the skilled computer program- mer. With NRI training you can be one of the increasing number of computer programmers using their skills to build a lop-paying career — even a business of their own — in this professionally and financially rewarding high-tech field. em ▼ The only programming course that includes a powerful AT-compatihle computer sysfr and programming software you keep Right from the start, NRI training gets you actively involved in the challenge or real-world computer programming. You learn how to create the kinds of hi 1 1- fe at ured , po wer f ul pro- grams today's employers and clients demand. And, unlike any other school, NRI lets you experience first-hand the power of an IBM PC/ AT-compatible computer system with modem, a full — megabyte of RAM, disk drive, and moni- tor — all yours to train with and keep. Plus you explore the extraordinary capabili- ties of not one or two but fo_m in-demand computer languages. You leam to design, code, run, debug, and document programs in BASIC, Pascal, C, and COBOL. In the process you become uniquely prepared for the wide variety of programming opportuni- ties available today. ▼ No previous experience necessary Immediately, you start getting the money-making job skills you need to secure a future in computer programming — no matter what your background. With NRI training you move easily from computer novice to computer professional with step- by-step lessons covering program design techniques used every day by successful micro and mainframe programmers. You'll find no heavy textbooks to plow through. No night classes to attend. Instead, NRI's at-home, step-by-step training covers all the bases, guiding you from the impor- tant fundamentals to real- world methods and techniques. With the help of your NRI instructor — offering one-on-one, personal guidance throughout your course — you quickly gain the skills you need to handle with confidence a wide variety of program- ming applications. You even use your modem to "talk" to your instructor, meet other NRI students, and download programs through NRI's exclusive program- mers network, PRONET. ▼ Send today for your FREE catalog Now you can have the professional and financial rewards of a career in computer programming. See how NRI at- home training gives you the experience, the know-how, the computer, and the software you need to get started in this top-paying field. Send today for your FREE catalog. If the coupon is missing, write to us at the NRI School of Computer Programming, McGraw-Hill Continuing Education Center, 4401 Connecticut Avenue, NW, Washing- ton, DC 20008. ~l SSI ■i.-'i r Schools McGraw-Hill Continuing Education Center 4401 Connecticut Avenue, NW, Washington, DC 20008 [jet Check one free catalog only □ Computer Programming □ Microcomputer Servicing D PC Systems Analysis □ Desktop Publishing and Design □ PC Software Engineering Using C D Word Processing Home Business Name (please print) .Age. Address j City Accredited Member, National Home Study Council . State . .Zip. 5415081 _J > C Q C CO ED 29 for $29.95 at Radio Shack Stores nationwide. — Ra- dio Shack 700 One Tan- dy Center, Fort Worth, TX 76102. CLAMP-ON METER. Amprobe s RS-3 amp/volt/ ohmmeter has been up- graded with the addition of high-energy protection to 600 volts. The RS-3 is CIRCLE 26 ON FREE INFORMATION CARD fused to protect both the user and the instrument against accidental misap- plication. The amp/volt/ ohmmeter offers a com- fortable shape and locking, all-weather test leads. It also features a magnified rotary scale for easy read- ings, and a pointer lock that captures readings in hard- to-see places. The full-ca- pacity, locking transformer jaws provide accurate read- ings and long instrument life. The RS-3 amp/volt/ ohmmeter has a list price of $74 85. — Amprobe In- struments, 630 Merrick Road, Lynbrook, NY 11563; Phone: 516-593-5600. DC POWER SUPPLIES. Housed in dark metal cab- inets that blend in with modern amateur-radio and communications equip- ment, Tripp Lite's PR-Se- CIRCLE 27 ON FREE INFORMATION CARD ries of DC power supplies give an integrated, profes- sional appearance to any radio or electronics in- stallation. The power sup- plies power practically all types of 12-VDC equip- ment, including base or mobile radios, test equip- ment, and other electronic gear. Continuous-duty per- formance stands up to ex- tended periods of use for reliable operation. The power supplies provide IC voltage regulation, auto- matic over-current protec- tion, and full-line operation. They are available in 3- to 60-amp sizes. Suggested retail prices for the PR-Series DC power supplies start at $38.50.— Tripp Lite, 500 North Orleans, Chi- cago, IL 60610-4188; Phone: 312-329-1777; Fax: 312-644-6505. R-E Try the tfecframcs. bulletin board system (RE-BBS) 516-293-2283 The more you use it the mare useful il becomes. We support 1200 and 24D0 baud op e rat ion. Parameters: 8N1 (8 data bits, no parity. 1 stop bit) or 7E1 (7 data bits, even parity. 1 stop bit). Add yourself lo our user tiles In increase your access. Communicale with other R-E readers. Leave your commenls on R-E with the STSOP RE-BBS 516-293-2283 w o z o EC t- o Li] _l LU 6 < IT 30 jnNv<'> your reliable source for a world of crystal clear communication i i • Commercial Two-Way • Microprocessors • Amateur/Experimental • Scanners/ Monitors/ Pagers • Satellite-Telemetry • Plus custom applications EXPEDITED ORDER SERVICE! FOR FREE CATALOG. CALL OR WRITE: JAN CRYSTALS RO. Box 06017 Ft. Myers, FL 33906 (813) 936-2397 TOLL FREE 1-800-526-9825 FAX ORDERS: 1-813-936-3750 VISA ^t^eSFBfe-' ^S*£*V si* «»ik« <&&&• $&' tf^fl* ■^i::*^ CIRCLE 104 ON FREE INFORMATION CARD CIRCLE 108 ON FREE INFORMATION CARD EARN YOUR DEGREE THROUGH HOME STUDY Our New and Highly Effective Advanced-Place- ment Program tor experienced Electronic Tech- nicians grants credit for previous Schooling and Professional Experience, and can greatly re- duce the time required to complete Program and reach graduation. Mo residence schooling re- quired for qualified Electronic Technicians. Through this Special Program you can pull ali ot the loose ends of your electronics background together and earn your B.S.E.E. Degree. Up- grade your status and pay to the Engineering Level. Advance Rapidly! Many finish In 12 months or less. Students and graduates in an 50 States and throughout the World. Established Over 40 Years! Write for free Descriptive Lit- erature. COOK'S INSTITUTE OF ELECTRONICS ENGINEERING gSfW"E 4251 CYPRESS DRIVE ^— »■*■■ JACKSON. MISSISSIPPI 39212 CIRCLE 58 ON FREE INFORMATION CARD NEW LIT Use The Free Information Card for fast response. WIRING GUIDE; from Car Audio Specialists Association/Vehicle Se- curity Association (CASA/VSA), 2101 L Street, NW, Washington, DC 20037; Phone: 202-828-2270; $14.95 (members), $24.95 (non- members). Originally presented as a series of articles in CASA/ VSA's monthly publication, struments — oscillo- scopes, IC comparators, digital multimeters, signal CIRCLE 40 ON FREE INFORMATION CARD the Mobile Electronics Monitor, the "Wiring Guide Series" has been released as a set of 12 leaflets com- plete with an index identify- ing all vehicles featured and a binder to which additional guides can be added. The guides feature wiring di- agrams that identify vari- ous OEM radio plugs, color codes, pin positions, and related information. Avail- able separately are individ- ual binders with index and single copies of guides in the ongoing series. To date. 17 guides have been published. TEST INSTRUMENTS BK-91; from B&K- PRE- CISION. Maxtec Interna- tional Corp., 6470 West Cortland] Street, Chi- cago, IL 60635; Phone: 312-889-1448; free. B&K-PRECISION s full line of electronic test in- CIRCLE 39 ON FREE INFORMATION CARD and function generators, video test instruments, component testers, power supplies, probes, and ac- cessories — is covered in this 68-page catalog. With a glossary of terms for each major project catego- ry, as well as summaries of key product features and selected product applica- tions, the catalog helps purchasers identify the right instrument for a given task. Complete specifications are provided both in the de- tailed product listings and in easy-to-use comparison charts. A complete line of accessories, designed to enhance the functionality of many different test in- struments, also is de- scribed. SECRETS OF RF CIR- CUIT DESIGN; by Joseph J. Carr. TAB Books Inc., Blue Ridge Summit, PA 17294-0850; Tel. 1-800-233-1128; $19.95. This hobbyist's guide to radio-frequency circuit the- ory and experimentation is written to demystify that part of the electromagnetic spectrum. Aimed at ama- teur experimenters, ham- radio operators, shortwave listeners, and electronics students, the book ex- plains in clear, nontechnical language what RF is. how it works, and how it differs from other electromagnetic frequencies. Broad in scope, with hundreds of helpful di- agrams and equations to clarify the text, the book explains how to repair vari- able circuits, align RF cir- cuits, and cope with elec- tromagnetic interference. With an emphasis on prac- tical applications, the book also shows how to design and wind inductor coils; de- sign and build simple wire CIRCLE 38 ON FREE INFORMATION CARD antennas with ten BASIC programs, RF amplifier cir- cuits, and preselector cir- cuits: and build a digital frequency-counter module. Also covered in the guide are the basics of receiver operation, the proper use and repair of components in RF circuits, and the prin- ciples of radio propagation from low frequencies to mi- crowave. BUILDING POWER SUP- PLIES; by David Lines. Master Publishing Inc., available at Radio Shack stores nationwide (Cat. No. 276-5025); $4.95. This book has two main goals: to provide a thor- ough understanding of how power supplies work, and to explain how the reader can build their own power supplies. Covering both regulated and unregulated CIRCLE 37 ON FREE INFORMATION CARD power supplies, the book describes the basic func- tion of each of the compo- nents in a power supply and how those compo- nents work together to form a functioning unit. Opening with a discussion of the fundamentals of AC and DC energy sources, the book provides in-depth looks at unregulated power-supply systems — including transformation, rectification, and filtering to produce a DC voltage from an AC source — and regu- lated power supplies — in- cluding the basics of how to control a DC voltage to close limits as input or out- put varies. Complete con- struction plans are in- cluded for three linear regulated power supplies and two switching regu- lated supplies. Using easy-to-under- stand text and clear illustra- tions, the book guides the reader through the design and construction steps. A c chapter on measurements, c calibration, and trou- h bleshooting closes the ^ book. r-e 2 31 ElEctrnnics DTfDDtJDD FREE CATALOG! ELECTRONIC TOOLS 4 TEST EQUIPMENT. Jensen's new Master Catalog, available free, presents major brand name electronics tools, tool kits, and test in- struments, plus unique, hard-to-find products for assembly and repair and custom field ser- vice kits available only from Jensen. All fully described and illustrated. Enjoy free technical support and rapid, post-paid delivery any- where in the Continental USA. JENSEN TOOLS INC., 7815 S. 46th St., Phoenix, A2 85044. Phone: 602-968-6231; FAX: 1-800-366-9662. 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FAX: 516-293-3315 FREE CATALOG OF TEST INSTRUMENTS & TOOLS is packed with thousands of prod- ucts for testing, repairing, and assembling electronic equipment. Featured are brand name instruments such as Fluke, Tektronix, Leader, Weller, 3M plus many more. Also in- cluded are DMM's, hand tools, power sup- plies, tool kits, test equipment, static supplies plus many other new products. Orders placed by 4 PM are shipped before we go home! CONTACT EAST, 335 Willow St., No. An- dover, MA 01845, (508) 682-2000, Fax: (508) 688-7829. CIRCLE 55 ON FREE INFORMATION CARD CABLE TV CONVERTERS AND DE- SCRAMBLERS SB-3 $79.00 TRI-BI $95.00 MLD-$79.00 M35B $69,00 DRZ-DIC $149.00. Special combos available. We ship COD. Quantity discounts. Call for pricing on other products. Dealers wanted. FREE CATA- LOG. We stand behind our products where others fail. One year warranty, ACE PROD- UCTS. P.O. Box 582, Saco, ME 04072 1 (800) 234-0726. CIRCLE 75 ON FREE INFORMATION CARD SIMPLY SNAP THE WAT-50 MINIATURE FM TRANSMITTER on top of a 9v battery and hear every sound in an entire house up to 1 mile away! Adjustable from 70-130 MHZ. Use with any FM radio. Complete kit $29.95 + $1.50 S + H. Free shipping on 2 or more! COD add $4. Call or send VISA, MC, MO. DECO INDUSTRIES, Box 607, Bedford Hills, NY 10507. (914) 232-3878. CIRCLE 127 ON FREE INFORMATION CARD 32 Spectrum Analyzer DAN DOBERSTEIN AND JOHN CARDONE A SPECTRUM ANALYZER IS AN 1NVALU- able tool for examining the com- ponents of a signal spectrum. It provides a way to measure such parameters as power, harmonic distortion, frequency response, and the amplitudes of complex components. With our calibrated 0.1 to 810-MHz spectrum ana- lyzer, repeatable, accurate mea- surements of power and frequen- cy are possible. The PC-based spectrum analyzer we present in this article offers features nor- mally found only in instruments costing many times more. Although the "guts"' of the ana- lyzer resides on a single PC board, an IBM XT or compatible computer is required to act as a display, as well as to precisely po- sition phase-locked loops (PLL's) for frequency control and to pro- vide look-up tables for power cal- ibration. Using a PC allows us to include such features as marker and della-marker readout of fre- quency and power, hardcopy printer output, instrument-set- ting memory so that "front-pan- el" settings can be saved and recalled, and tunable FM demod- ulation. Refer to Table 1 for com- plete instrument specifications. A modestly configured PC is re- quired to work with the spec- trum analyzer: A single 360K floppy drive, CGA or EGA video adapters, and 512K RAM are all that's required. The card either plugs directly into an 8-bit slot or, with an external power supply, runs off the paraltel printer port. That dual interface allows the user a wide choice of host ma- chines — from basic laptops to high-end machines. So if you al- ready have a PC, for about S300 you can have a very capable in- strument that allows spectrum analysis from 0. 1 MHz to over 800 MHz. Before we go into the theory be- hind our spectrum analyzer, let's briefly discuss what this instru- ment actually does, and how it operates. Spectrum analyzer displays Electronic signals, whether they are periodic, aperiodic, or transient, can be shown in a time-domain plot where the am- plitude is a function of lime (left side of Fig. 1). All time-domain plots have an associated spec- trum that can be graphically de- scribed in a frequency-domain plot where the amplitude of the signal is a function of frequency. (Mathematically, that's done using the Fourier transform.) It is in the frequency-domain where the spectrum analyzer draws a picture, so that you can analyze the signal spectra in question. A spectrum analyzer is used to display the power distribution of a signal as a function of frequen- cy, as shown in the right side of Fig. 1. It is basically a tuned re- ceiver with selectable frequency ranges and intermediate-fre- quency (IF) bandwidths. A spec- trum analyzer separates an input signal into its various frequency components and displays each component as a vertical line on a CRT, The height of each vertical line on the display represents the amplitude of each frequency component, the horizontal posi- tion of each line indicates the fre- quency location. Figure 1 shows three examples of input signals represented in > c o c CO 33 TABLE 1— SPECIFICATIONS Parameter Highband Lowband Notes Frequency Range 50-810 MHz 0.1-100 MHz Available Spans 0.625, 1.25,2.5,5, 10,25, 50, 100, 200, 300, 400, 500, 600, 800 MHz 0.625, 1.25. 2.5, 5, 10, 25, 50, 100 MHz 0.625 MHz to 800 MHz Resolution Bandwidths (RBW) 10 KHz, 280 kHz 10 kHz, 280 KHz Maximum frequency re solution is 10 kHz Power Accuracy* ±3dB ± 3 dB from 4-1 00 MHz (Below 4 MHz, ±5-6dB) With min. 6-dB (50-ohm) pad on input. Sensitivity > - 98 dBm > -92 dBm With internal attenuation set to dB and 50-ohm source. VSWR Input (50 ohms) <1.2(6dB) <1.3(10dB) 50-ohm pad on input. Spurious Response (Birdies) < - 95 dBm <-92dBm Unit outside of PC case, 50-ohm terminal on input. Intermodulation Products <-95dBm <-90dBm (280-kHz RBW) Dynamic Range >58 dB (all bands and RBW's) Internal Attenuation 0, 10, and 20 dB Maximum Input Power + 10 dBm Frequency Accuracy <10 kHz Limited by 10-kHz RBW. Reference Oscillator 4.000 MHz crystal, ± 100ppm All VCO's phase-locked to this reference. FM Demodulator 280-kHz bandwidth, quadrature detection, manual volume control. Tuning stepsizes 1 25 kHz at 280 kHz RBW; 62.5 kHz at 10 kHz RBW. FM demodulator is for wideband FM, Narrow- band FM is demodulated, but because of the 1 0-kHz RBW, it cannot be seen on the display Power Requirements + 5VDC at 0.45A, ■+ 1 2VDC at 0.1 2A Interfaces PC bus or parallel interface (Centronics) System Requirements 360K disk drive, EGA or CGA graphics adapter, 51 2K Ram, DOS 3.0 or higher. 'The power accuracy noted above is for factory calibrated units. Kit builders who use the generic calibration tables will degrade by about 3 dB from the above numbers, assuming proper adjustment. Relative power accuracy within a narrow band (less than 25 MHz) is usually better than ± 2 dB over a 45 to 50 dB range of power for kit builders and factory calibrated units. o z o I w _i u 6 □ < DC time and frequency domains. When two different signals, f a and /" b , are simultaneously ap- plied to the input of the spectrum analyzer (Fig. 1-a), two frequency components would appear as ver- tical lines at 200 kHz [Q and 300 kHz (f b ). The amplitude of f a would be twice that of f b . With an amplitude modulated (AM) signal applied to the input [Fig. 1-b), the waveform is separated into its carrier frequency, f c , and two sidebands. An apparently perfect sine wave, f s (Fig. 1-c), might show harmonic distortion as multiple frequency components of the input signal. Now that we have an idea of what a spectrum analyzer dis- plays, let's take a look at some of the techniques used in the opera- tion of these instruments. Techniques There are three types of spec- trum analyzers: the swept filter, heterodyne, or heterodyne with tracking filter type. Although the swept-filter method (Fig. 2-a) is seldom used, we will discuss it first because it's easy to under- stand. The swept-filter analyzer sweeps, or tunes, a bandpass fil- ter over the frequency band of in- terest. The voltage output of the filter is plotted against frequency, resulting in the spectrum dis- play. The problem is that narrow- band, wide-tuning range filters just don't exist. The most common type of spec- trum analyzer, however, is the heterodyne type (Fig. 2-bj. With that technique, the bandpass fil- ter is fixed at some frequency and a swept oscillator, in combina- tion with a mixer, performs the same function as the swept filter. The fixed filter determines the resolution of the analyzer. The 3- dB bandwidth of that filter is re- ferred to as the resolution band- width (RBW). The advantage of mixing, or heterodyning, which converts energy at one frequency to energy at another frequency, is that the filter is cut to a particular frequency and, therefore, its characteristics are fixed. Its also much easier to build a sweepable oscillator than a narrow-band swept filter. Voltage controlled os- 34 FIG. 1— TIME AND FREQUENCY DOMAINS of input signals. Two different signals applied at the same time results in two separate frequency components (a). An AM signal is displayed with its carrier and two sideband frequencies (b). A sine wave that appears perfect on an oscilloscope may show harmonic distortion on a spectrum analyzer (c). cillators (VCO's) are used for that purpose. There are problems, however, with the heterodyne type. In the mixing process, unwanted fre- quencies can appear in the flxed- filter bandwidth — additional noise is added and there is a re- duction in dynamic range (the difference between the smallest signal detectable and the largest signal allowed). One way to help eliminate the unwanted heterodyne frequen- cies is to use tracking filters (Fig. 2-c). A tracking filter is a filter that is tuned by voltage. In prac- tice, tracking filters are used ahead of the mixer stage to re- duce the number of frequencies that are mixed with the oscillator. A tracking filter is just a swept filter used in different way. It is designed to follow the oscillator (usually a VCO) so that some pro- tection from the unwanted fre- quencies is provided. Our analyzer uses the hetero- dyne principle in combination with tracking filters. Fixed ce- ramic 10-kHz and 280-kHz band- pass filters provide the two reso- lution bandwidths. Phase locking Phase locking a VCO takes an otherwise unpredictable beast and nails down its frequency. VCO's, if left on there own. wander in frequency due to tem- perature, vibration, and a host of other causes. Frequency calibra- tion is impossible with such vari- ations. Frequency wandering can be gready reduced by phase- locking the VCO with a highly stable source, such as a quartz- crystal oscillator. The VCO's in our analyzer can wander as much as 1 to 5 MHz. When phase- locked to the 4.000-MHz refer- ence, the frequency drift is only a few hundred hertz. That accuracy does not come without a price. Phase locking to a given frequency takes a signifi- cant amount of time. That re- sults in longer sweep times when compared to sweeping an un- locked VCO. Also, phase- locking forces frequency steps on the VCO, whereas the unlocked VCO can be put at any frequency, at least in theory. For our design, the advantages of PLL's far out- weigh the disadvantages. The big picture Figure 3 shows the overall block diagram of the spectrum analyzer. At the heart of the unit is a Zenith tuner module (IC17). The tuner takes highband inputs from 50 to 810 MHz and converts them to a 45-MHz IF, which is the first IF stage. After that con- version, the first of two Signetics NE615 receiver ICs (IC16) down- converts the 45-MHz IF to a 10.7- MHz IF, which is the second IF stage. The 10.7-MHz IF is tapped off and sent to another NE615 (IC13) where the 10.7-MHz is downconverted to the standard 455-kHz IF, which is the third IF stage. Figure 4 shows the circuit of the first 45-MHz IF stage. Of the four local oscillator's (LO's) used, three are phased-locked using Motorola's MC44802 IC (IC14, IC15, and IC23). The LO for the 10.7-MHz IF is crystal-controlled by XTAL1. The PLL's used for the tuner IC also perform band switching, which will be dis- cussed in more detail below. Those PLL's are self contained and have a serial interface. A 4- MHz crystal oscillator (XTAL2. Fig, 5) is used as a common refer- ence for all the PLL's, as indicated in the block diagram (Fig. 3). The circuit of the second and third IF is shown in Fig. 5. FM demodulation is provided by IC13 and IC16. The output of the 10.7- MHz IF is suitable for wide-band FM such as standard FM radio broadcast. The FM output of the 455-kHz IF is not very clean but can be used for narrow-band FM signals such as voice-only broad- casts. However, only the FM from the 10.7-MHz IF is sent to the au- c dio amp (IC22). § The NE615 receiver ICs (IC13 <3 and IC16) have a received-signal ^ strength indicator (RSSI) out- 2 35 ). A heterodyne type with tracking filter eliminates undesired heterodyne frequencies [ c). PC BUS OR PARALLEL INTERFACE iii. x/ 7 PLL2 (IC23> LOWBAND 0.1 -100MHz PLL1 MC15t I L0 Vm (IC24) UPCONVERT 145MHz IF HIGHBAND 50-81QMH2 DAC (IC7) AT0D(IC121 L0 V™ TUNER (IC171 AGC 45MHz IF RSSI 10.7 MHz IF -J (IC16) FM EXTERNAL SPEAKER H PLL3 (IC14I RSSI L0 V T | 455kHz IF (IC13) FM T AUDIO AMP [IC221 COMB OUT FIG. 3— A BLOCK DIAGRAM OF THE SPECTRUM ANALYZER shows the tuner module, phase-locked loops, receiver blocks, DAC, ADC, and the PC bus connection. 36 COAX FEED C4 .047 R5 22K R6 22K 18 R13 4701 17 (FEED X" FROM FIG.5 XTAL 2, PIN 8 i 4MHz OSCILLATOR KI 16 )r/~ EN FROM FIG.10 IC9. PIN 5 IN COMP REF. DATA IC15 MC448D2 PLL1 FROM FIG 10 :S-a,PIN III H11 22K 14 \\1 K 66 n 85 RFfN TO REAR* PANEL VIA COAX IC17 OE-175-14 TUNER UHF V ^cc LO OUT + 5V DECOUPLING CAPACITORS O +5V +33.3V CSS 220(if RG. 4— THE FIRST 45-MHz IF STAGE. The tuner takes highband inputs from 50-810 MHz and converts them to 45 Mhz. the O.l to 100-MHz band. A lowpass filter, consisting of L5. C68. and C69. with a 100-MHz bandwidth is used on the input to the mixer to reduce unwanted frequency products at the out- put. The tuner is set up to receive the 145-MHz IF from the NE602 mixer. The NE602 is turned off for the highband mode using Q7 as an on/off switch, which is con- trolled from a PLL1 band-switch- ing output. The input is fed directly into the tuner module (IC17) in the highband case. The tracking fil- ters are Internal to the tuner, as previously described. Two band- pass trackers are used with a buffer amp between them. The output of the second filter is fed to the mixer for downconversion to the 45-MHz IF. A 45-MHz band- pass filter, with a 6-MHz band- width, follows the mixer. The local oscillator (LO) must be 45 MHz above the input signal to mix to the 45-MHz IE For the 50 to 810-MHz bandwidth, the tuner VCO must have a range of 95 to 855 MHz. The LO from the tuner is internally buffered and is sent to PLL1 (IC15, Fig. 4) for fre- quency locking. The 45-MHz IF is fed through a 6-dB attenuation pad (R16-R18, Fig. 4) and a tuned circuit to the mixer for the 10.7-MHz IF. The attenuation pad is used to reduce signal gain from the tuner and to provide a wide-band termination for the output of the tuner mixer. The tuned circuit, consisting of LI, C8. and C7 (as seen in Fig, 5). acts to match impedance, filter, and to adjust the voltage gain. The tuning of LI (Fig. 5) affects the overall gain and noise floor of the instrument. The 10.7-MHz IF is produced by mixing the 45-MHz IF with a 34.3-MHz third overtone crystal- controlled oscillator, which is tuned by L2. The 10.7-MHz out- put of the mixing process is bandpass filtered by two 10.7- MHz ceramic filters (FL1 and FL2) with a buffer amp between them. The 10.7-MHz IF is fed to a limit- ing amp and a quadrature tank (Tl) to perform FM demodula- tion. The functions of LO. mix- ing, amplification, and FM de- modulation are performed by IC16. The bandwidth of the 10.7"- MHz ceramic filters is 280 kHz. With the tuner or lowband LO set to a step size of 125 kHz and swept over the frequency span, those filters provide the 280-kHz resolution bandwidth (RBW) using the received signal strength indicator (RSSI) from IC16 (Fig. 5). The RSSI is lowpass filtered by R41 and C43 to smooth the voltage. The lowpass filter forms what is commonly called the video bandwidth. The audio from the 10,7-MHz IF is lowpass filtered by C52 and R43 and sent to the audio amp (IC22). A sample of the 10.7-MHz IF is taken just after the first 10,7- MHz ceramic filter, passed through FL5 and sent to IC13 for downconversion to 455 kHz. The additional ceramic filter is used to further reduce unwanted mix- er products and to provide isola- tion between the 10.7-MHz IF and the 455-kHz IF. To produce the 455-kHz IF. a 10.245-MHz LO is needed. That LO is provided by phase-locking the oscillator of IC13 using PLL3 (IC14. Fig. 5). The oscillator of IC 13 in our analyzer has been set up as a VCO using a varactor di- ode (Dl). A sample of the LO is buffered by Q6 and sent to PLL3 (IC14) for error generation and locking. The LO is swept from 10,21375 MHz to 10.27625 MHz in step sizes of 3.90625 kHz. That is a total span of 62.5 kHz; the step size of the tuner LO, or the lowband LO when the RBW is set to 10 kHz. It is necessary to sweep the 10.245-MHz LO because a step size of 3.90625 kHz is not possi- ble with the tuner LO or the low- band LO phase-locked loops. Those step sizes must fall within the 10-kHz bandwidth of the 455- > c q c — . EG s 37 FIG. 5— SECOND AND THIRD IF STAGE. IC16downcon verts the 45-MHz IF to a 10.7-MHz IF, which is tapped off and sent to IC13 where the second IF is again downcon verted to the standard 455-kHz IF. Pretuned ceramic filters FL3 and FL4 provide the 10-kHz resolution bandwidth (RBW). CD u Z o DC F o Q Q < E kHz ceramic filters. That com- bination of dual LO sweeping with the 455 kHz ceramic filters provides the 10-kHz RBW. As with the 280-kHz RBW. the 10- kHz RSSI is lowpass filtered using R36 and C42. That forms the video bandwidth for the 10- kHz RBW. The 10.245-MHz LO is not swept in the 280-kHz RBW. As with the 10.7-MHz IF, the 455-kHz IF is FM demodulated using quadrature detection (T2). The comb generator, shown in Fig. 8, provides a wide-band test signal. Transistor Q8 is biased to produce the harmonics of the 4.0-MHz reference. XTAL2. That signal has detectable harmonics past 500 MHz. Now that we've gone over the operating theory in some detail. FIG. 6— RF SIGNAL PROCESSING block diagram. we will discuss some of the more important IC's in this design, and the reason why each of them were chosen. Tuner module The tuner is a CATV type made by Zenith. No modifications to the tuner are needed to use it in our analyzer. Along the bottom is a row of pins for the AGC input, + 5 VDC, VCO tuning input, IF out and band-switching inputs. Band-switching inputs are used because LOs cannot sweep from 95 to 855 MHz. Instead of one LO. there are four that are switched in one at a time to provide the complete span. Table 2 shows the points where the LO is switched at various frequencies. The frequencies shown in the table are with respect to the input frequency; to get the LO frequen- cy, just add 45 MHz. Not only is the LO switched, so is the mixer! Two mixers are used: one for the VHP band and one for the UHF band. The mixers are switched by the same inputs as the LO so no additional switching logic is needed. The band switching re- sults in two effects: a momentary delay in the sweep at the band switching points, and a slight step up or down in the noise floor at the switching points. The switching also affects the opera- tion of the tracking filters. The tracking filters are internally tied to the VCO control voltage so that the input signal is always kept in the center of the bandpass filters. PLL IC MC44802 The Motorola MC44802 IC, TABLE 2— BAND SWITCHING BANDS SWITCH SETTINGS VHFB + Highband Superband UHFB + Lowband VHFLow(50to100MHz) + 12 Open Open Open Open VHF High (100 to 200 MHz) + 12 + 12 Open Open Open Super Band (200 to 372 MHz) + 12 + 12 + 12 Open Open UHF Band (372 to 810 MHz) Open Open Open + 12 Open Lcwband (0.1 to 100 MHz) I 12 + 12 Open Open + 12 used in IC14, IC15, and IC23, is tailor made to interface to a band-switching tuner. Figure 9 shows a block diagram of that IC. All the switching logic is provided in the IC for band switching. An on-board prescaler with associ- ated divide counters enables the MC44802 to directly sense and control VCOs up to 1.3 GHz. An error/driver amp is also included that is used to provide VCO tun- ing voltages from to 35 volts. Programmable reference dividers are also present in the IC. All of the internal settings of the MC44802 are controlled via a three- wire interface. You can continually change the contents of the VCO divide coun- ter by sweeping the VCO being controlled by the step size se- lected. You can control tuner band-switching by writing to the band-switching register of PLL1 (IC15). Transistors Q1-Q4 are used as drivers for the tuner band-switching inputs. To set the PLL to a particular frequency, divide the frequency by the step size, truncate, and insert the resulting number into the divide counter. For example, if you want to set the tuner VCO frequency to 400 MHz using a step size of 125 kHz, the divide > c Q C CD to 39 CO y z o s f- b LU Q < FIG. 7—0.1 T0 100 MHz FRONT END. An oscillator/ mixer, IC24, provides the up conversion to the 145-MHz IF. The oscillator in IC24 is swept from 145 MHz to 245 MHz to cover the 0.1 to 100-MHz band. ooaxfeedJ^ FIG. 8— THE COMB GENERATOR provides a wide-band, 4-MHz test signal. counter should be loaded with 400/0.125 = 3200 counts, of course you would also have to set the band switches accordingly. All of that programming is done by the host PC. A complete dis- cussion of the details of program- ming this 1C is too long to be presented here. You can refer to the Motorola Linear and Interface Data Book if you would like more information on programming the MC44802. Because of the high frequencies involved, the use of sockets is not recom- mended for these IC's. Receiver IC NE615 The Signetics NE615 IC con- tains all the necessary compo- nents to do frequency con- version. The RSSI output has a 90-dB dynamic range, although our analyzer only has a 60— 70-dB dynamic range due to compres- sion in the tuner. The oscillator can be either crystal controlled or LC-tank controlled. If a varactor diode is added to the LC tank, you have a VCO. One feature of the NE615 that is not used in our unit is the au- dio mute. That input allows for killing the audio output when no signal is present. The IF section has a total gain of 90 dB. The high gain can cause stability problems and consequently per- formance of this IC is greatly effected by circuit board layout. If you build a kit, do not put a nor- mal socket on this chip! Individ- ual, high-frequency, pin-type sockets can be used, but those are hard to come by. ADC0834 The only thing that is unique about this ADC used for IC12 is its serial interface. Just four wires are needed to interface this IC to a processor. The ADC is used to convert the analog RSSI voltages to 8-bit digital informa- tion which is read by the PC. Di- ode D2 provides the reference voltage of 4.3 volts. This ADC has 40 I j TTTTTTT T~ ■H3J 1 i i IL \ I i i I i I i i i i B7 B6 B5 B4 B2 B1 SWITCH BUFFERS OSCILLATOR 62.5 hHz PROGR, REFERENCE DIVIDER A I 7-BFT LATCHES MC448Q2 fj5>- T SCL SDA I9S3H2 3906Hz 7812Hz 15625Hz TRI-STATE PHASE COMPARATOR BUS RECEIVER HI r -O* PRESCALER V 15-BIT PROGRAMMABLE DIVIDER FIG. 9— BLOCK DIAGRAM OF THE MOTOROLA MC44802 IC. All switching logic is pro- vided in this PLL IC. An on-board prescaler with associated divide counters allow the MC44802 to control VCO's up to 1.3 GHz. four channels, all of which are programmable. Channels and 1 are used for the two RSSI volt- ages from the NE615s. Channel 2 is unused. Channel 3 is con- nected to the DAC and is used for self testing. As with the MC44802, the details of pro- gramming this IC are too lengthy to be presented here and the reader is referred to National Semiconductor's Databook. 8-bit DAC AD558 This Analog Devices DAC was chosen for IC7 primarily because of its self contained reference and voltage output. It also needs only one supply voltage, + 12 VDC. In keeping with the serial interface approach, a 74164 8-bit shift reg- ister (IC8) is tied to the input data of the DAC. Three lines, a clock, data, and strobe, are use to insert the shift register and load it into the DAC, DC to DC converter The PLL s used need + 33 VDC to control the VCO's over the spans used. Motorola's MC34063 (IC3) can be configured as a step- up or -down DC-to-DC converter. In our case it is used to convert + 12 VDC to + 33 VDC. Only 3 mA are needed to drive the three PLL's. The input and output volt- ages are heavily filtered by C57, C100, R24, C55, C99. and R62, as any ripple on the supply will show up as unwanted FM on the LO's. Interfaces As already stated, the analyzer can communicate via the PC bus or the parallel port LPT1 through LPT4. A header is provided on the board for a ribbon cable to con- nect to a Centronics-type adapter cable. If the card is operated ex- ternal to the PC, an external power supply must be provided. The supply plugs into a 3-pin, Molex-type connector toward the back of the board. A good quality DC supply with -1-5 volts at 1.0 amp and +12 volts at 0.4 amps is adequate. None of the DIP switches need to be set to select PC or LPT inter- face. When the Centronics cable is attached to the computer, it pulls pin 30 of the connector low which selects the LPT interface. The software, however, must be instructed by the user which in- terface is going to be used. That is done using the setup program, which will be discussed in our next issue. You can actually oper- ate the card plugged into the PC bus using the LPT interface. In that configuration, the PC inter- face is used just for power. Figure 10 shows the PC bus in- terface circuitry. The entire LPT interface is accomplished by using two 74LS244s (IC4 and IC5) and one 74LS04 (IC6). The 74LS244S are three-state octal drivers, which are used to buffer the signals to and from the LPT interface. The PC bus interface is considerably more complex. It consists of one 74LS688 com- parator (IC20), two 74LS138's 3- to-8 decoders (IC18 and IC19), two 74LS374 8-bit latches (IC9 and IC10), one 74LS245 bidirec- tional buffer (IC21), and one DIP switch (SI). The DIP switch is used to select the PC bus ad- dress. The default address is 768 decimal. The default DIP-switch setting for SI is: positions 1-5 on, positions 6 and 7 off. If another address is desired you will have to use setup to change the address used by the software and of course set the DIP switches to the new address. Details of setting the address switches are included in the README.DOC file contained in the SPECAN.ARC file. SPEC- AN.ARC can be copied from the Radio-Electronics BBS (516-293-2283. modem settings: 1200/2400, 8N1). If you never in- tend to operate the analyzer from the PC bus IC9, IC10, IC18, ICI9, IC20, IC21, and IC11 can be re- moved from the circuit. The PC interface does a com- parison of the address bits A3 through A8 to determine where a block of eight decoded addresses will fall. Although eight read/ write addresses are decoded, only two of the eight write addresses are used, and one of the read addresses. That is mod- eled after the LPT interface, which has two write registers and one read register. Operation The PC host controls all as- pects of the spectrum analyzer's control and data collection. After the user selects a start or center frequency and a span frequency, computations are performed to set up the various LO's that need > c a c CO 41 o z o a. F O LLI -I UJ 6 Q < IC9. PIN2 Q IW-a i/, 74244 16 IC4-b I IW-c V« 74244 12 M/8 74244 « 1C9, PIN3 9 IC4-d Vi 74244 12 AA A A A A A ^riA A A T2 „ , 4 .„ 8 ]6 8 ICS-b B ICS-c 4 3 J , CA . IC5-fJ 2 ICS-e 17 ICS-f 15 2k. 'r?;L:Ai, ,7.™ ak .„, Vi 74244 Vt742« !,.«»« '/< 742*4 v« 74244 v» 74244 IC6-e .'« 74LS04 IC6-1 J/6 74LSH 31 lie J^ 6 o * * • o v CONTROL REG V DATA RFT, status lire — s/ — data nr < : FIG. 10— PC BUS INTERFACE CIRCUITRY. The entire LPT interface is performed by IC4 and IC5. Those two 74LS244's buffer the signals to and from the LPT interface. 42 All resistors are %-wait unless other- wise noted. R1. R33— 3300 ohms R2, R31, R32, R43— 5600 ohms R3-R12, R37, R38, R46, R47, R49, R50, R66— 22,000 Ohms R13, R22, R23, R27, R39, R40, R48, R53. R54. R57. R61— 470 ohms R14, R56. R60— 1000 ohms R15, R28-R30— Not used R16, R17, R24—18ohms R18, R45, R59. R62— 68 ohms R19— 180 ohms, Vi-watt R20. R52— 1800 ohms R21— 47,000 ohms R25—240 ohms R26 — 180 ohms R34, R35, R51, R55, R58— 56.000 ohms R36, R41, R42— 100,000ohms R44, R64— 10,000 ohms R63— 390,000 ohms R65— 10,000 ohms x 7 SIP resistor Capacitors CI, C2, C36, C40, C44, C45, C56, C63, C64, C91— 1 m-F, 50 volts, tantalum C3, C48, C60— 0.1 m-F polyester C4, C49, 059—17,000 pF polyester C5, C6, C9-C18, C32, C46, C47, C61, C88--C90— 0.001 fiF ceramic disc C7, C62— 330 pF ceramic disc C8, C68, C69— 100 pF T ceramic disc C19, C38, C66— 22pF ceramic disc C20, C26, C34, C37, C41— 10 pF ceramic disc C21. C35, C67, C72, C73— 1000 pF chip C22 — 1 nF, 50 volts, ceramic disc C23, C71, C74— 2.7 pF, ceramic disc C24, C25. C97— Not used C27-C31, C33, C50, C70, C76-C87, C92-C95— 0,01 n-F, ceramic disc C39 — 200 pF, ceramic disc C42— 0.047 u.F. polyester C43, C51— 0,01 n.F, polyester C52— 1000 pF, polyester C53 — 1 (xF, 50 volts, tantatum or polyester C54— 1000 pF polyester C55, C57, C99, C100— 220 nR 35 volts, electrolytic C58— 220 u-F, 16 volts, electrolytic C65— 5 pF, ceramic disc C75— 0.01 ti.F polyester C96— 10 u.F, 16 volts, tantalum C98— 10 \lF, 16 volts, tantalum PARTS LIST Semiconductors IC1 , IC2— Not used IC3— MC34063, step-up voltage reg- ulator, Motorola IC4, IC5— 74LS244, three-state octal driver tC6— 74LS04, hex inverter IC7-AD558, 8-bit A/D converter, Analog Devices IC8— 74LS164, 8-bit par out shift register IC9, IC10— 74LS374, three-state octal driver IC11— 74LS32, quad or gate IC12— ADC0834, A'D converter. National Semiconductor IC13. IC16— NE615, receiver. Signelics IC14, IC15, IC23— MC44802, PLL, Motorola IC17— OE-175-14, tuner. Zenith IC18, IC19— 74LS138, decoder IC20— 74LS688, address decoder IC21— 74LS245, bus transfer IC22— LM386, audio amp. National Semi- conductor 1C24 — NE602, oscillator/mixer, Signetics Q1-Q4, Q7— 2N3906, PNP transistor Q5, Q8— MRF901, double emitter NPN transistor, Motorola Q6— 2N3904, NPN transistor D1, D4— MV209 or MV2105, varactor di- ode, Motorola D2— IN5229B, 4.3 volts, Zener D3— 1N4003, diode LED1— Any red light emitting diode Other components Li— T10307, 0.15 rrtH, 7-rnm can type. Toko L2— T10407, 1,0 mH, 7-mm can type Toko L3— 421F224, 5.8 to 3.7 mH, 7-rnm can type, Mouser L4 — 220 mH coil, Mouser L5— 3 turns of #30 AWG wire on #23 drill, 18=0.138" L6— 5 turns of #30 AWG wire on #42 drill, LS-0.2" L7— 3 turns of #30 AWG wire on #42 drill, LS = 0.138" T1 — +2IF128, 10-mm can type. Mouser T2— 42IF102, 10-mm can type, Mouser FL1, FL2, FL5— SK M1, 10.7-MHz ce- ramic filter. Toko or Murata Erie FL3, FL4— CFM2-455E, 455-kHz ce- ramic filter, Toko XTAL1— 34.3000-MHz standard crystal XTAL2— X107, 4.00-MHZ TTL oscillator S1— 7-position DIP switch Connectors J1 , J2. J4 — Female F-type bulkhead con- nector J3— RCA audio jack, PC board mounted (90°) J5, J6 — F-type connectors are part of tun- ing assembly (IC17) J7— 3-pin type. Molex, 0.156" O.C. power connector P2— 36-pin DIP header Two RCA male connectors for coax to tuner connection Miscellaneous • Bottom shield— 3-7'8" x 3-7/8" sin- gle-sided PC board with glass epoxy, copper side facing away from board. Four VS-long screws, four 4-40 nuts and bolts, four lock washers and insulating washers. • Lowband shield— 2-1/4"x2-1/2" sheet metal. • Rear panel with mounting screws. • 3 inches of 0.047 mtniture coax, • 16 inches of RG174 coax. Note: The following items are available from DKD Instruments, 1406 Par- khurst, Simi Valley, CA 93065; (805) 581-5771: A complete kit including a 5-1/4 inch disk with all executable files, and manual, $255,00; Cen- tronics interface cable, $13.00; power cable, $4.00; an assembled, tested, and calibrated unit, $500.00. Send check or US postal money order. Allow 3 to 5 weeks for delivery. California residents add 6% sales tax. to be swept using the PLL's. Once everything is properly set up, the computer starts sweeping the ap- propriate LO s and collecting data via the ADC data from the RSSI outputs. If the RBW is 280 kHz, the 10.7- MHz RSSI output is read. If the RBW is 10 kHz, the 455-kHz RSSI is read. The LO's are not swept continuously, but rather in steps. The steps are determined by the internal settings of the PLL's, The steps used for the tuner are 125 kHz and 62.5 kHz. Steps for the 455-kHz IF are 3.90625 kHz. Those different step sizes are needed to accommodate the two filter bandwidths of 280 kHz and 10 kHz. As the computer is sweeping the LO's, it is also con- trolling the AGC via the DAC, which is there to keep the gain flat. The overall basic sequence is • Command LO's to the next fre- quency. • Set AGC level from the look-up table. • Allow adequate time for set- Uing of PLL's. • Read RSSI voltage. • Calibrate RSSI data to Power in dBm. • Display the power/ frequency pair on the screen. • Repeat. Those operations are performed continuously by the computer until interrupted by the user. > In our next edition, we'll go g over the software, kit con- c struction, tuning, power calibra- 2j tion, and troubleshooting of the S spectrum analyzer. r-e ® 43 ELECTROCARDIOGRAPH LAST MONTH WE DISCUSSED THE OPERATION OF THE C1R- cuitry for our electrocardiograph, or ECG. This month we'll build the unit and explain how to use it. ■ ^^^^^S£. your health (earn about medical electronics with the Radio-Electronics electrocardiograph. H. EDWARD ROBERTS, M.D. t I 1 co o z o cc O UJ _i LU O □ < EC WARNING!! This article deals with and involves subject matter and the use of materials and substances that may be hazardous to health and iife. Do not attempt to implement or use the information contained herein un- less you are experienced and skilled with respect to such subject matter, materials and substances. Furthermore, the information contained in this article is being provided solely to readers for educational pur- poses. Nothing contained herein suggests that the monitoring system described herein can be or should be used by the assembler or anyone else in place of or as an adjunct to professional medical treatment or advice. Neither the publisher nor the author make any represen- tations as for the completeness or the accuracy of the information contained herein and disclaim any liability for damages or injuries, whether caused by or arising from the lack of completeness, inaccuracies of the infor- mation, misinterpretations of the directions, misapplica- tion of the information or otherwise. \ ECG construction The ECG is relatively simple to build. Double- sided plated-through, silk screened, and solder masked PC boards, as well as all of the necessary components, are available from the supplier listed in the sources box. Software for checkout, data- acquisition, and display are also available. How- ever, we are providing foil patterns so you can make your own PC boards, and we'll post the software on the RE-BBS (516-293-2283, 1200/2400, 8N1] as ECG .ARC. Mount the components according to the parts- placement diagrams — Fig. 1 for the controller board and Fig. 2 for the front-end board. Most of the IC's are CMOS, and must be handled according- ly. A grounded work bench and soldering iron are strongly recommended, and a static wrist strap is also a good idea. We also recommend you use IC sockets for all the IC's. Install the IC sockets first, making sure they are flush with the PC board. Then solder in the remain- ing components on both boards. Make sure the polarized components are properly oriented before you solder them. Inspect the finished boards thor- oughly before beginning the system checkout. Do not insert the IC's in their sockets just yet, and don't wire the two boards together until instructed to do so. The finished controller board is shown in Fig, 3 and the finished front-end board is shown in Fig. 4. Checkout Begin the system checkout by attaching an RS-232 cable between your PC and the DB25 con- nector on the controller board. The cable should be wired as shown in Fig. 5 if your PC has a 9-pin communications port, or as shown in Fig. 6 if your PC has a 25-pin communications port. Apply power to the PC and measure the voltage at pins 1 and 8 of IC19. Pin 1 should read about + 12V and pin 8 about - 12V. Also, check pin 14 of IC26 for 5 volts. If those voltages are correct, install the IC's in the controller board and proceed with the checkout. Install an unused battery in the B3 battery clip and insert the battery in the holder. Press the reset button on the controller board and measure the output of voltage-regulator IC32 at pin 3. If the output is about 5 volts, the power-on circuitry is working. Remove the battery from the circuit. The remainder of the checkout will be accom- plished by running a checkout program that pro- vides a step-by-step procedure to verify each section of the controller and the front end. Some of the checkout software resides in the ECG program EPROM, IC9, on the controller board. The re- mainder of the checkout software runs on your PC. When the checkout process is complete, install the two boards in the case and prepare to take your first ECG. Take an ECG Skin electrodes with a conductive adhesive back- 44 .- FIG. 1— MOUNT THE COMPONENTS lor the controller board as shown here, and use IC sockets for all the IC's to reduce the risk of component damage during assembly. ing are recommended to attach from the source listed in the the leads from the ECG to the sources box. Stick one electrode body. The electrodes are available on each wrist and ankle and at each of the six torso locations shown last month in Fig. 3. Use alcohol to clean the area where COMPONENT SIDE of the controller board. SOLDER SIDE of the controller board 45 «— R59-» , *-R63 •— neO-*' »-R57 •— R62-» «-R58 C16* — • #-fi52-* s-R45^» icia "~C27"-- {■ • " " ■-•-■ "I ■ f f ' » ■ ■'• G21 FM7 □S021 "J wf «-R61-» ,, \ »-R49~» «-R51-» SS022 . *-RSQ -»4B>U «^R 40 -» ■-. «-R48-» ffl ' C37S ■ ; IC4 ' *__ , tl u * * * * »v< HS03 ■tea r n ] Clip IC5 * C38b IC6 C4S C40 7 R30 f R34 * i « . »T * L . . . . » . »l 4 *''k \ *-R13-« — R32- — R35- -R31 -R36 C34 > 1C.1 ' I _l D7 Dl — /*" ► V, *' V-R42-* ; * *-R27-» ! } ' R41 . . *-rim-» *-Rt4-«| #-fM3-* ,»-R28r*:*; nsG7i . B * I'll * . t l • * i * * . * * « DS027 R66 ■ J , ©S029 •-R23 -♦rs «-R64 -• R24 IC2 •-R24-* < « ■ ' ) I -J i I : • . t . i jc3,. ? *g; 07 Dl D4 Db D 5 D9 Dl 1 013 08 D2 D3 D6 _ 016 D10 012 _. D14 _ PA SOI Q see 513 V' JO. J HI S07 □ SOS 03 06 □ a SOS S03 D D SOB S04 R8 I _ OWW 3Hg □ a SOS SOI 5 d a 9010 S016 R9 _TT_ 012 D14 018 D19 lul ana S013 SOU S019 S017 D D D D $014 S01? S020 S016 FIG. 2— MOUNT THE COMPONENTS for the front-end board as shown here. Most of the IC's are CMOS, so care must be used in handling them. the adhesive electrodes will be trode in an area with minimal to each skin electrode. placed to improve the connection body hair. Using the alligator To acquire the ECG, make sure and the signal, and place the elec- clips, attach the appropriate lead the ECG controller and your PC u z o o HI _i UJ 6 < COMPONENT SIDE of the front-end board. SOLDER SIDE of the front-end board. 46 PARTS LIST— FRONT-END All resistors are 14-watt, 5%, unless otherwise noted. R1-R9. R1 3— 20,000 ohms R10, R24. R60, R63— 30,000 ohms R11— 1800 ohms R12, R25, R44— 10,000 ohms, potentiom- eter R14, R18, R26— 4700 ohms R15, R17— 19,200 ohms R16— 39.2 ohms. 1% R19— 200.000 ohms R20-R22, R41— 100 ohms R23— 1500 ohms R27— 910 ohms R28, R39. R40, R43, R55, R59, R62, R67— 10,000 ohms IR29, R46, R48— 15,000 ohms R30— 200,000 ohms, potentiometer R31, R36— 680,000 ohms, 1% R32— 500,000 ohms R33— 68 ohms R34 — 15,000 ohms, potentiometer R35— 100 ohms R37, R38, R43, R61— 470 Ohms R42, R64— 1000 ohms R45, R51— 680,000 ohms R47— 5000 ohms, potentiometer R49— 330,000 ohms R50, R58— 2200 ohms R52, R56— 1.5 megohm R53— 150 ohms R54 — 150,000 Ohms R57— 12,200 ohms R65— 3300 ohms R66— 1000 ohms, potentiometer Capacitors C1-C1 0—220 pF. 1000 volts, ceramic disk C11, C19. C20— 10 mP, tantalum CI 2, C13— not used C14, C23, C24— 1 (i.F, ceramic C15— 0.001 m-F. metal film C16— 39 pF, ceramic disk CI 7 — 120 pF, ceramic disk C1S— O.01 fiF, metal film C21, C22, C31-C47— 0.47 fiF, ceramic disk C25-C30— 1 \i.F, tantalum C48, C49— 47 u.F, 16 volts, electrolytic Semiconductors IC1-IC3, IC9, 1C10— LM348 op-amp IC4 — AD 625 instrumentation amplifier IC5-— TL431C precision voltage reference 1C6 — 4051 analog switch IC7^4052 analog switch ICS — Altera EP320 PAL IC14, iC15— OP18012 optoisolator IC16, IC17—PS2501 A optoisolator 1C18, IC20— 78L06AC voltage regulator IC19— 78L05AC voltage regulator D1-D20— lN914diode Q1, Q2— (RFD123 N-channel HEXFET Other components B1-B3— 9-volt battery are connected with the RS232 ca- ble used when you checked out the system. Load and run the data collection batch file, ECG.BAT, in your PC. Input the patient information that the pro- gram requests, terminating each ORDERING INFORMATION Note: The following items are available from DataBlocks, Inc., Glenwood, GA 30428, (912) 568-7101. • Design package including sche- matics, assembly instructions, and checkout- and plot-software design specifications (ECG-DP): $27.00. • Front-end PC board, controller PC board, and design package from above (ECG-PC): $74.00. • Complete kit of parts, including both PC boards, IC's, sockets, passive components, design package, ECG software, and checkout software (ECG-KIT): S289.00. • Lead kit consisting of 50 feet of 29-gauge shielded cable, 10 al- ligator clips, heat-shrink tubing, and instructions (ECG-LDJ: $53.00. • EPROM containing ECG soft- ware, ECG resident portion of checkout software (ECG-PROG): $45.00. • Set of four programmed PAL's (ECG-PAL): $67.00. • Case as shown with mounting hardware (ECG-CASE): $29.00. • Package of 100 self-adhesive electrodes (ECG-EL): $20.00. Please include $5.00 shipping and handling for design package and electrodes, $10.00 shipping and handling for all other products. Georgia residents must add sales tax. answer with a carriage return. After the last response, press the reset button on the ECG to initi- ate data collection. Make sure the patient does not move during the collection process. You will see a message on the PC as soon as the data collection process starts. After about 30 seconds you will see a message on the PC indicating that data is being transferred between the ECG and the PC. That is an in- dication that the ECG has finished collecting data. After the data has been transferred, your PC will begin processing it for display. Depending upon the speed of your PC, the graphs of the ECG will appear after a few seconds of processing. In addi- tion to the plots shown on the CRT, each of the plots may be sent to your dot-matrix printer for a permanent record. Now let's examine the hard- ware and software interactions involved with taking the ECG you just finished. Firsts assume the PARTS LIST— CONTROLLER BOARD All resistors are Vi-watt, 5%, unless otherwise noted. R1 — 10 ohms R2, R7-R1 0—10.000 ohms R3-R6, R15, R16— 1000 ohms R11— 7500 ohms R12— 24,000 ohms R13~-30,000 ohms R14— 10,000 ohms x 8, SIP Capacitors C1-C22, C25. C26, C28. C29, C33. C34. C42 — 0.47 jiF, ceramic disk C23, C24— 22 pF, ceramic disk C27, C30— 0.001 nF, metal film C31— 220 pF, ceramic disk C32— 10 u.F, 10 volts, electrolytic C35, C38, C39— 10 n-F, 10 volts, tantalum C36, C37, C40, C41— 1 pF, 10 voSts, tantalum Semiconductors IC1— Z80 CPU IC2-IC5, IC12— 74HC245 bus transceiver IC6, ICS— Altera EP320 PAL IC7— Altera EP600 PAL IC9— 27C256 EPROM IC10, IC11— 55257 static RAM IC13— 74HC688 equality comparator IC14—74HC138 1-of-8 decoder IC15— 62C52 UART IC16, IC17— 74HC573 octal latch 1C18— 74HC74 dual D flip-flop SC19— MC145406 RS232 transceiver IC20— AD0829 A<'D converter IC21, IC22— DAC0830 D/A converter IC23, IC24— NE5532A op-amp IC25— 74HC14 hex Schmitt inverter IC26— 74HCO0 quad NAND gate IC27— PS2501A-2 optoisolator IC28, IC31— not used IC29— ICL7660 DC-DC converter IC30— 78L06AC voltage regulator IC32— 7805 voltage regulator D1-D4— 1N914 diode D5— 5.1-volt Zener diode D6 — 6-volt Zener diode Q1— IRFZ10 N-channel MOSFET Other components XTAL1— 2.4576 MHz crystal XTAL2— 8.00 MHz oscillator S1 — SPOT momentary contact switch S01— DB25 connector RS232 ports between the ECG and the PC have been connected, the PC has been booted, and the ECG batch file run. As soon as the ECG reset button is pressed, the microprocessor in the ECG controller boots up and enters a wait loop, waiting for the PC to announce to the ECG that it is time to begin taking data. After the initialization prompts for pa- c tient information, and the name £ of the file that will be used to store ^ the ECG data has been entered g through the PC keyboard, the PC 2 47 FIG. 3— THE FINISHED CONTROLLER BOARD will look similar to this one, although this is an early prototype board. Inspect the finished boards thoroughly before beginning the system check- out. FIG. 4— THE FINISHED FRONT-END BOARD. This, too, is an early prototype, so your board won't look exactly like this one. Do not wire the two boards together until you are told to do so. 00 g z o g o < software transmits a control character to the ECG that causes it to start the ECG data-collection process. The ECG turns both batteries on and enters a calibration rou- tine. The first part of the routine determines whether the batteries are charged. That is accom- plished by digitizing the output of IClO-d in the front-end elec- tronics with the differential in- puts to the instrumentation am- plifier, both connected to ground through IC7. If the batteries are good, the voltage measured will be the 2.5-volt offset from the dif- ferential amplifier. If both bat- teries are not fully charged, the voltage from the divider formed from R31, R34, and R36 will change, causing the output of IClO-d to change from the ex- pected 2.5 volts. If the batteries are not good, the ECG outputs a "low battery" message to the PC and stops. If the batteries are good, the channel calibration routine is entered. The channel calibration rou- tine determines the appropriate channel offset for each of the nine input channels. That is ac- complished by sequentially con- necting each of the input channels to the positive input of the differential amplifier and comparing its voltage to that of the Wilson electrode connected to the negative input of the differen- tial amplifier. If those two volt- ages are equal, the digitized output of the differential ampli- fier will be its offset voltage, 2.5 volts. If the input lead is not equal to the Wilson electrode, a bias is added to the channel by incrementing the output of ei- ther IC21 or IC22 in the appropri- ate direction; IC21 is used for coarse changes, while IC22 is used for smaller increments. That change is added to the out- put of the other D/A converter at the summing junction of IC24-b and passed to the front-end board. On the front-end board, the change goes through the optical isolator IC17-a and op-amp IC9-C to the summing junction of IC3- c, where it adds with the input channel being measured. After an appropriate delay to let the voltages in the loop settle, the output of the differential ampli- fier is sampled again. The pro- cess is continued until the difference between the input channel and the Wilson electrode voltage is within acceptable lim- its, at which time the system se- quences to the next channel. The digital values required to adjust the analog output of IC21 and IC22 to bring the channel biases within acceptable limits are stored in the software to be used during the data-acquisition pro- cess. The data-acquisition routine is entered immediately after the last channel bias has been deter- mined. This routine digitizes the difference between each input lead and the Wilson electrode, in sequence, and stores the sample in memory. Prior to digitizing the sample, the channel bias values for the channel being sampled, determined during the calibra- tion sequence, are retrieved from the software and placed in the D/ A converters, as previously de- scribed. Each channel is sampled as rapidly as the pro- cessing and loop settling time will permit. The software then enters a wait period before sam- pling the next data set to achieve a 400-sample-per-second rate on each of the nine channels. Two thousand samples are obtained from each channel and placed in memory for subsequent transfer to the PC for display. At the completion of the data- acquisition phase, the ECG con- troller turns the batteries Bl and B2 off and signals the PC that the data is available for transfer. When the PC detects that it ac- knowledges the message and starts its transfer routine. The ECG also sets up a transfer rou- tine and the data is passed from the ECG to the PC. At the con- clusion of the transfer, the ECG powers itself down, waiting for the PC to signal that it is time to acquire another ECG. The PC be- gins to process the data it just received during the transfer. The data transferred to the PC must be processed before it can be displayed as one of the twelve standard ECG leads. Remember that the digitized information is the difference between the input channel and the Wilson elec- trode. The first six ECG leads, however, are combinations of in- 48 put channels compared with one or more other input channels. For example, consider the stan- dard ECG lead I. This lead is de- fined as the electrical activity from the heart measured on the left arm with respect to the right arm. Let SI designate a sample from the right arm with respect to the Wilson electrode, and S2 designate a sample from the left arm with respect to the Wilson electrode. In other words: 51 = RA-W 52 = LA-W Now, I = LA-RA = (S2 + W}-(S1+W) I = S2-S1 so that the PC must subtract Sample 1 from Sample 2 to get lead I. In an analogous manner leads II and 111 are derived from their definitions as: D=S2-S3 111 = SI -S3 The augmented leads are some- what more complicated to derive from the samples. Recall that an augmented lead is denned as the electrical activity on one of the three input leads with respect to the other two leads. For example: AVR = RA-{LA+LF) Now, 51 = RA-W 52 = LA-W 53 = LF-W so that AVR = S1-S2-S3-W Recall that W, the Wilson elec- trode, is the sum of RA, LA and LF (W=RA + LA + LF) so that: 51 = RA-W = RA-RA-LA- LF=-LA-LF 52 = LA-W = LA-RA-LA- LF= -RA-LF 53 = LF-W=LF-RA-LA- LF=-RA-LA Adding the samples: Sl + S2 + S3= -2RA-2LA -2LF= -2W or W=-(Sl+S2 + S3)/2 and AVR = S1-S2-S3-W = Sl-S2-S3 + (Sl+S2 + S3)/2 AVR = SI + (SI - S2 - S3)/2 Using the same arithmetic, it can be shown that AVL = S2 + (S2 - SI - S3)/2 AVF = S3 + (S3 - S2 - SI )/2 The chest leads VI through V6 are defined as simply the elec- trical activity on the lead with re- spect to the Wilson electrode. The processed data is stored on your disk drive under the file DB25 MALE CONNECTOR ATTACHES TO ECG GND DTR CTS RX RTS TX DSR CD DB9 FEMALE CONNECTOR ATTACHES TO COMPUTER FIG. 5— THE RS232 CABLE between your PC and the DB25 connector should be wired as shown here if your PC has a 9-pin communications port. CO ?.<< DTR 7 GND 19 6 DSR 18 5 CTS RTS RX TX DB25 FEMALE CONNECTOR ATTACHES TO COMPUTER OB25 MALE CONNECTOR ATTACHES TO ECG FIG. 6— IF YOUR PC HAS A 25-PIN communications port, wire the the RS232 cable between your PC and the DB25 connector as shown here. name you entered. In addition, three traces are plotted on the CRT with each trace broken into four parts. The traces are seg- mented as follows: Trace 1 = Lead I, AVL, VI, V4 Trace 2 = Lead II. AVR, V2, V5 Trace 3 = Lead III, AVF. V3. V6 You should have enough infor- mation now to use the ECG. How- ever, if you're not a doctor, don't think of yourself as one — and be sure to see a medical doctor if you suspect any health problems, R-E > c a c o c i 51 — i ,, na toe 1 a INPUTS S 4 J PRIK 2 < i < * 1 i i > < > i ' 2 ^_ 3 3 4 5 6 7 3 2 ^ t i i i. 5 » e .6 , 7 7 , 8 ^ 8 » 20 < TER- 20 IARV — ~Oi 5M1NAL OWTOR JS SECONDARY Si TERMIN MONfTDR TXD RXD RTS CTS DSR 110 DTR a . . . this is the data on the txd line . . This is the data on the rxd line . . . T 6 ... CO 55 54 42 ... 77 90 44 22 88 42 43 44 45 56 22 ... 66 76 FIG. 2— WIRING DIAGRAM for the termi- nal/monitor. Connectors J4 and J5 are standard DB-25 males. o z o 17>'^ ■ ''-'•2 yC< '" ■>'< ; \ ; '?■ /" V '-- V'M^/ jtj vfe'v^' " -;V ■■■ ir' ' 'v ''' ' Vl»V '■-'s? - l '', : , ;'i .V>i-" ^ 'J Hi/s simple circuit will protect your stereo speakers in the event of amplifier failure. IF YOU'VE HAD FIRST-HAND EXPER1- ence with damaged speakers due to a faulty amplifier, or if you val- ue your speakers enough to want to prevent such damage in the first place, then the circuit de- scribed in this article is for you. The circuit will protect speakers against an amplifier that may have a shorted output stage and thus deliver excessive DC volt- ages that will easily ruin a speak- er coil. If your amplifier has a sound-processing delay after the power has been turned on, a functionally similar circuit is al- ready built in. This article will give you a basic idea of the delay's function and how it works to pro- tect the speakers. The circuit is designed for solid-state ampli- fiers and is not necessary for tube-type amplifiers that have output transformers. (An output transformer blocks any DC from the speaker terminals.) MARK A. VAUGHT The circuit is very versatile and can be customized for many dif- ferent applications. Plans for home stereo, automotive, and commercial PA/guitar amplifier applications are included. The most common cause of speaker failure is catastrophic amplifier failure. That's in con- trast to the conception that the speaker has been overdriven by an amp that's operating nor- mally Most often the speaker power level has been chosen to match the driving amplifier. Semiconductors designed to handle high current, such as bi- polar power transistors and MOSFETs. usually short when they blow out. Often these de- vices are connected directly to an amplifier's DC power-supply rails or through a small amount of re- sistance that can't effectively lim- it the current when the short occurs. The DC level of an amplifier's power supply is designed to ac- commodate the peak power levels that occur when the amp is driv- ing the speaker at full power. A 100-watt amplifier has power- supply rails of at least 40 volts. Under normal operating condi- tions, that level would never be applied to the speaker coil for more than a few seconds. How- ever, if an output device in the amp shorts, the DC is applied to the speaker continuously. In the case of a 100-watt amplifier, that causes a power dissipation of: P D =(40V/speaker resistance) 40V Speaker resistance is usually one to two ohms less than the AC im- pedance. If a blown amplifier is > connected to a 100-watt speaker § with a 7-ohm DC resistance, the 5 power being dissipated is: P D =(40V/7II)40V g =228 watts ® 55 to o z o pc F O LU The speaker will be able to dissi- pate that power for only a couple of seconds before the coil is damaged due to excessive heat. When the protector circuit senses a DC voltage on the speak- er line, it activates a relay whose contacts are in series with the speaker: after two seconds the re- lay disconnects the speaker until the DC is removed, A fuse is inad- equate for this application be- cause the value needed to protect the speaker against DC will blow out at peak power levels during normal operation. Conversely, a fuse value chosen to allow peak power operating levels will not protect the speaker against a DC voltage. The protector circuit al- lows peaks to occur in the power level and also protects the speak- er against DC. It should be used in conjunction with a fuse value calculated from peak power lev- els. The fuse should be placed as close to the amplifier as possible, if not in the same chassis, and is therefore not shown in the pro- tector circuit's schematic. Circuitry The protector circuit's, sche- matic is shown in Fig. 1 and the power supply is shown in Fig. 2. Up to four individual protector circuits can be powered from one supply, although most applica- tions will require only one or two circuits per chassis. The optional 9-volt DC output jack can be used to power a footpedal or fuzzbox, eliminating the need for a DC wall transformer when the cir- cuit is used to protect guitar-am- plifier speakers. The power sup- ply can be modified for different applications, and we'll talk about them later. Referring to Fig. 1 , the voltage- divider resistors R3— R6 are used to bias the positive and negative inputs of the window comparator formed by ICl-a and ICl-b. The inputs are biased at plus and minus 3 volts. The voltage divid- er also provides a 9-volt reference for the negative input of com- parator ICl-c. Resistors Rl and R2 form an input voltage divider fed from the speaker terminals of an audio amplifier. The input divider is ref- erenced to analog ground, and the output of the divider is con- nected to the negative and positive inputs of the window INPUT TERMINATION SEE TEXT T R2 4.7K + o 12VDC INPUT ICl-b V< LM339 FIG. 1— IF AN AMPLIFIER OUTPUT SHORTS, this circuit will protect your speakers from the harmful DC voltage that will be present at the amplifier's speaker outputs. FIG. 2— THE POWER SUPPLY can be used for up to four individual protector circuits. The optional 9-volt DC output jack can be used to power an electric-guitar footpedal or fuzzbox. comparator (ICl-a and ICl-b). The outputs of ICl-a and ICl-b are open-collector stages, wired together, and pulled high through R7. That forms a wired or function and completes the window comparator. When the output of the R1-R2 voltage divid- er exceeds the reference levels set by R4 and R5, the output of the window comparator goes low and removes the bias from Ql. The input voltage at which that hap- pens is determined by the value of Rl. The formulas for calculat- ing Rl are presented later in this article. Transistor Ql is turned off while the output of the win- dow comparator is low, thus al- lowing timing-capacitor CI to begin charging through R8. Under normal input condi- tions (an AC audio signal), the output of the window com- parator will return to a high level when the input returns to the plus and minus 3-volt range. That biases Ql into conduction and immediately discharges CI. If a DC signal large enough to trigger the window comparator is present on the input, thenQl will remain in its off state and CI will charge until it reaches 9 volts with reference to the power-sup- ply ground. When CI reaches 9 volts it triggers comparator ICl-c causing its output to go high and bias Q2 into conduction via R9. When turned on, Q2 grounds one end of relay RY1 thereby activat- ing it and disconnecting the au- dio passing through its contacts from the speaker. The relay con- tacts will remain open until the DC input is removed from the protector circuit. Diode Dl pro- tects Q2 against reverse-bias spikes generated by the relay coil. The circuit has two separate grounds: a speaker ground and a power-supply ground. Under no circumstances should these two grounds be connected together. If two circuits are used together, then three entirely separate grounds will exist: a power-sup- ply ground and a speaker ground for each circuit (see Fig. 3-a), Some stereo amplifiers, es- pecially those used in car-radio amplifiers, have differential or floating-ground outputs for each channel and cannot be con- nected together. Figures 3-a, -b, and -c are AC model diagrams showing the equivalent connec- tion paths between two circuits 56 TABLE 1 R6 4r R6 15K V LEFT RIGHT CHANNEL STEREO CHANNEL RECEIVER . LEFT CHANNEL LEFT RIGHT CHANNEL STEREO CHANNEL RECEIVER ::ru R2 HSh 30K R1+R2 ^7 . ^7 FIG. 3— THE CIRCUIT HAS A SPEAKER GROUND and a power-supply ground that should never be connected together; a shows that the current flowing in either loop is not a function of the other; b shows the power-supply capacitor from a (C s ) replaced by a wire; and, in c, the equiv- alent resistance between the two speaker grounds is shown as 30K. operating from a single power supply. Figure 3-a clearly shows that the current flowing in either Loop 1 or Loop 2 is not a function of the other. The speaker grounds return to the common power supply rails through the voltage- divider resistors R3-R6. Figure 3-D shows the power-supply ca- pacitor from 3-a, which is seen as a short to AC, replaced by a wire. Finally, in Fig. 3-c, the equivalent resistance between the two speaker grounds is shown as 30K. DO NOT short the two grounds together under any cir- cumstance. If the amplifier speaker grounds are connected inside the amplifier, they should NOT be connected at the speaker pro tec- POWER 4-OHM LEAD 8-OHM LEAD RMS PEAK R1 FUSE RMS PEAK R1 FUSE OUTPUT VOLT- VOLT- VALUE VALUE VOLT- VOLT- VALUE VALUE OF AGE AGE IN IN AGE AGE IN IN AMP (W) OHMS AMPS OHMS AMPS 10W 6.3V 8.9V 5.2K 2.2A 8.9V 12.7V 9.2K 1.6A 20W 8.9V 12.7V 9.2K 3.2A 12.7V 17.9V 15.2K 2.2A 30W 11.0V 15.5V 12.5K 3.9A 15.5V 21.9V 19.6K 2.7A 35W 11.8V 16.7V 13.8K 4.2A 16.7V 23.7V 21.5K 3.0A 40W 12.7V 17.9V 15.2K 4.5A 17.9V 25.3V 23.3K 3.2A SOW 14.1V 20.0V 17.4K 5.0A 20.0V 28.3V 26.6K 3.5A 60W 15.5V 21.9V 19.6K 5.5A 21.9V 31.0V 29.6K 3.9A 75W 17.3V 24.5V 22.4K 6.1A 24.5V 34.7V 33.7K 4.3A 85W 18.4V 26.0V 24. 1K 6.5A 26.0V 36.9V 36.0K 4.6A 100W 20.0V 28.3V 26.6K 7.0A 28.3V 40.0V 39.6K 5.0A 120W 21.9V 31.0V 29.6K 7.8A 31.0V 43.8V 43.9K 5.5A 140W 23.7V 33.5V 32.4K 8.4A 33.5V 47.3V 47.8K 5.9A 150W 24.5V 34.7V 33.7K 8.7A 34.7V 49.0V 49. 7K 6.1A 175W 26.5V 37.4V 36.8K 9.4A 37.4V 52.9V 53. 9K 6.6A 200W 28.3V 40.0V 39.6K 10.0A 40.0V 56.6V 58.0K 7.0A 250W 300W 31 6V 44 7V 44.8K 49.7K 11, 2A 12.3A 44.7V 49.0V 63.3V 69.3V 65.3K 72.0K 7.9A 8.7A 34.7V 49.0V tion circuit's chassis. High cur- rent is assumed to be flowing in each speaker ground lead and connection of separate ground leads anywhere except inside the amplifier will degrade perfor- mance. Calculations To calculate the value for Rl, which determines the time it takes CI to reach nine volts, the following example analysis is pre- sented. The first step is to calcu- late the RMS (average) voltage applied to the speaker terminals to obtain the rated amount of power. We'll arbitrarily use 100 watts and a speaker load of 8 ohms. From the equation: P = (I 2 )R we can substitute values 100W = (I 2 )8 divide by 8 12.5 = I 2 take the square root of both sides 1 = 3.53 amps From the equation: V=IR we can substitute values V=8(3.53A) = 28.28 volts RMS As a final check use the formula p=rv we can substitute values P = 3.53A(28.28V) = 99.82 watts To calculate the value for Rl we use the equation: t(V IN (R2))/V OUT )-R2 = Rl and substitute values = ((28.28V(4,7K))/3V)-4.7K = 39.60K To calculate the fuse value for amplifier short-circuit protec- tion, use the equation: Vp = V RMS /0.707 and substitute values 28.28V/0.707 = 40volts From the equation: I=Vp/R we can substitute values 40V/8 ohms = 5 amps If you would rather avoid mak- ing all of the calculations. Table 1 shows the correct resistance val- ues to be used for Rl for 10- to 300-watt applications. Appropri- ate fuse values are also provided in Table 1. The next step is to calculate the maximum time that CI will charge, and the voltage level it will reach before it is discharged, under normal operating condi- tions. This is a necessary analy- sis in order to prove that the circuit will not trigger falsely when peak audio power levels are reached. The lowest frequency normally associated with audio is 20 Hz. It has the longest time period (50 milliseconds) in the audio spectrum so we'll use it for analysis of the speaker protector circuit. (An actual audio signal is quite complex, but the complex- ity of the waveforms only de- creases the time that CI will charge, so we'll therefore use 20 Hz.)' > c Q C m 57 e, = E M (sin(360/)) we divide by E M e,/E M = sin(360/) we now take the inverse sign sin-l(e,/E M ) = 360/' and divide by 360f (sin-l(e,/E M )]/360f=t now we substitute values (s in- 1 { 28 . 28/40) )/360(20Hz ) = 45/7200 = 6.25 ms From those equations we can conclude that, for the sine wave of Fig. 4-a to travel from to 28 volts (0.707 x peak value), it takes 6.25 ms, or one eighth of the total period (50 ms) of the waveform. 6.25 ms is also the time it takes the sine wave to re- turn to zero volts. Therefore: 6.25 ms(2)=12.5 ms 12.5 ms is the total time CI will charge (4-e). The last step is to calculate the voltage level of CI at t = 12.5 ms, and we'll assume that e c is the capacitor voltage at t, E is the power-supply voltage (12V), e equals 2.718, t equals 12.5 ms.C equals 22 |iF. and R equals 68K. Now we take the equation: e r = E(l-e-« CR ») FIG. 4— SHOWN IS THE INPUT TEST SIGNAL (a), the Q1 base voltage (d), and the Q1 collector voltage (c). is between 28 and 40 volts, we'll first assume that e, is the in- stantaneous voltage level (28.28 VRMS), E M is the maximum or peak voltage level (40.00V P ), the frequency is f (20 Hz), pi (it) is equal to 3. 14, t is the time for sine wave to reach 28.28 V RMS , and that 2k radians equals 360 de- grees (and we'll stick to degrees from this point on). That out of the way, from the equation: ■ 2 INCHES- o z o i LU I LU 6 < MAIN FOIL PATTERN shown actual size. Capacitor CI will charge when- ever the input voltage exceeds the RMS voltage level necessary to produce 100 watts if Rl is equal to 39. 6K. Figure 4 shows the analysis waveforms for the cir- cuit; shown is the input test sig- nal (a), the Ql base voltage (fa), and the Ql collector voltage (c). Referring to Fig. 4-a, to calculate the time that the input waveform POWER SUPPLY FOIL PATTERN Shown actual size. and substitute values = 12( 1 — 2 7i8- 12 - 5ms/(22,1F)6SK ) = 12(0.0084) = 100 mV The speaker protector circuit will disconnect the amplifier from the speaker after a 2-second interval using the values shown for R8 and CI. That amount of time will protect the speaker un- der most circumstances. Charg- ing time for CI to reach 9 volts can be calculated by rearranging that equation and assuming that e equals 2.718, In is the natural log (the inverse of e x ), E is the power-supply voltage (12V), e c is the capacitor voltage (9V), t is the time for C to charge to 9V, C equals 22 jxF. and R equals 68K. The rearranged equation is: t = CR(ln(E/E-e c )) now we substitute values t=(22 u.F(68K))(ln(12/(12-9))) = 1.49(1.39) = 2.0 seconds To change the time delay for the speaker protector circuit to dis- connect the speaker from a DC voltage use the equation R8= t/1.39C to recalculate the value of R8. Construction Construction of the protector 58 SPEAKER INPUT SPEAKER GROUND SPEAKER OUTPUT O— INPUT FROM POWER SUPPLY FIG. 5 — PARTS-PLACEMENT DIAGRAM for the protector circuit. The 5-amp relay will mount right on the board, while the 1 5-amp relay must be mounted on the edge of the board using double-sided tape. + o 12VDC OUT 120VAC INPUT FIG. 6— PARTS-PLACEMENT DIAGRAM for the power-supply board. PARTS LIST All resistors are '/i-watt, 10%. R1 — value depends on your setup (see text and Table 1) R2— 4700 ohms R3-R6— 15,000 ohms R7, R8— 100,000 ohms R9— 2200 ohms Capacitors C1— 22 u.F, 35 volts, radial electrolytic C2— 470 uP, 35 volts, radial electrolytic Semiconductors IC1 — LM339N quad open-collector voltage comparator 1C2— 7812 12- volt regulator D1—1N4004 diode D2— ECG 5065A 3-volt Zener diode (required for optional 9-VDC out- put, see text) Q1, Q2— 2N2222 NPN transistor BR1— ECG 5882 1-amp bridge rectifier Other components T1— 120/1 2- VAC 300-mA transformer RY1 — 5- or 15-amp relay (see text) J1 — optional 9-VDC jack (whatever type best suits your needs) Miscellaneous: PC boards, AC plug and line cord, 18-gauge stranded hookup wire, cabinet(s), speaker- input and -output jacks (RCA jacks, spring-terminal board, etc.), solder, etc. Note: The following items are available from Applitron Elec- tronics, 2721 Creswelt Road, Bel- Air, MD 21014: Kit of parts for the speaker protector circuit includ- ing an etched and drilled PC board and all parts that mount on it for $14.95. Please specify the value of R1 you desire (stan- dard 10% values only) and P.A. guitar, home stereo, or auto- motive version. Add an addi- tional $3.50 for the optional high-current (15 amp) relay. A kit of parts for the 12-voit supply is also available that includes an etched and drilled PC board and all parts that mount on it for $14.95. Include $1.95 postage and handling for each kit or- dered and allow 3-4 weeks for delivery. Maryland State resi- dents must add 5% sales tax. circuit depends on the intended use. Once you have a clear idea of the application, then you can customize the circuit to meet your needs. To use the circuit to protect car-stereo speakers, re- place R4 and R5 with 3-volt Zener diodes. That will ensure that the window-comparalor reference voltages, with respect to analog ground, will be independent of the DC supply voltage. For power levels below 100 watts, you can use the 5-amp relay shown in the parts list; above 100 watts, you must use a 15-amp relay. The parts-placement diagram for the protector circuit is shown > G Q C CO 59 in Fig. 5. The PC board is config- ured for on-board mounting of the 5-amp relay that the author used. A compatible relay with a dif- ferent pinout can be used. How- ever, it may have to be mounted on the edge of the board using double-sided tape; it will then have to be hardwired to the board. The parts-placement di- agram for the power-supply board is shown in Fig. 6. After mounting all compo- nents, solder leads of adequate length to the boards, and use dif- ferent colors for the speaker and power ground leads to avoid con- necting them together. Next, con- nect the power leads between boards, and connect an AC line cord to the power supply. The au- thor's completed unit, con- taining a protector circuit for both the left and right channels and one power supply, is shown in Fig. 7. The completed boards can be $gS>* DSOs Limited Quantity Model 3060D LBO-5825 jpM8S_$2999 $29SI $1999 ■■mmmm-\ RF CONNECTORS BNC Self-Terminating Receptacles (Built-in Resistance) When Ihe plug is removed, Ihe receptacle termination closes to mainta n Ihe internal circuit electrical current automatically. 40-MSs DSO'60-Mfc Analog The 30600 is a CRT readout, 40- Mas Digital Storage and 60-MHi Real Tine Oscilloscope featuring 4k memory, sine and pulse interpola Son, X1 00 expansion and video Sine select ol field land 1 ■ * '. **_• * 5-MSr-s DSO/35-MHz Analog A versatile DSO and 35-MHz real time oscilloscope packed with features thai are rial normally found on DSOs of its class, it uses a separate A/D converter lor each channel, Also available are reliable high quality circular connectors for sophisfcaled industrial applications. Call tor a tree catalog. 1 800-372-1616 212-691-9050 in NY direct /ound DIHECT SOUND CORPORATION 1 50 FIFTH AYE. , SUITE W ■ NEW YORK. 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Complete coverage ot Theory of Operation — Read manual, view 1-hour 22-minute video I FREE INFORMATION PACKAGE! Call 1/800-537-0589 Viejo Publications, Inc. 5329 Fountain Ave., Dept. REA Los Angeles, CA 90029 CIRCLE 192 ON FREE INFORMATION CARD FIG. 7— HERE'S THE AUTHOR'S PRO- TOTYPE. It contains a protector circuit for both the left and right channels and one power supply. The entire unit is only about 4 inches wide by 6 inches long. mounted in a case like the one pictured in Fig. 7. Otherwise you can use whatever case you like. When drilling holes in plastic cases, start with a small drill bit and work your way up to the final size. Otherwise you may find yourself with a handful of plastic fragments. As a final word, the circuit is designed to protect speakers from excessive DC levels caused by amplifier faikire. However, it will not protect a speaker that's rated at power levels much less than the driving amplifier can supply — only your own common sense in keeping the volume down will protect your speakers in a situation like that. r-e Eli Try the bulletin board system (RE-BBS) 516-293-2283 The more you use it the more useful it becomes. We support 1200 and 2400 baud operation. Parameters: 8N1 (8 data bits, no parity, 1 stop bit) or 7E1 (7 data bits, even parity, 1 stop bit). Add yourself to our user files to increase your access. Communicate with other R-E readers. Leave your comments on R-E with the SYS OP, RE-BBS 516-293-2283 60 «H«-" *>-**-» )t- "-M-" <►-«-•» "-H-" ■ »-H-" HC-f n n ?i n ih i"! n t-K- Hf-f -H-" IF YOU"VE BEEN LOOKING FOR A WAY to generate high voltage, you've undoubtedly run across the volt- age doubler. Voltage doubling using diode-capacitor combina- tions is a common practice. How- ever, whole banks of doublers, called cascades, can also be used for producing extremely high DC voltages from moderate to high AC voltages. Such high DC volt- ages may be needed for TV sets, lasers, air purifiers, industrial smoke-stack dust removers, negative-ion generators, and, of course, for experimenting, on which we'll concentrate here. Half-wave doubler Figure 1 shows a half- wave volt- age doubler; we'll assume that CI and C2 are initially discharged. During the first half-cycle shown in a, the upper input terminal is positive and the bottom negative, so Dl conducts and CI charges to about 170 volts peak. Diode D2 can't conduct, since it's back-bi- ased, so C2 discharges through R L . In the second half-cycle (£>), the analysis is similar, except that D2 conducts and C2 charges. The circuit is really a transfor- merless voltage amplifier. While Tl can provide isolation, as well as increase the AC voltage ini- tially going into the doubler, the amplification due to the doubling action would occur without it. When the polarity reverses, both the input voltage and the charge across CI are in series like two batteries, producing about 340 volts peak. One problem, though, is that a half- wave doubler can't be used with a load that draws much current. Full -wave doubler Let's see how a full-wave voltage doubler is related to and built from both positive and negative half-wave rectifiers. Figure 2-a shows a half-wave rectifier with a positive output, Fig. 2-b shows the same version with a negative output, and Fig, 2-c shows the two combined into a full-wave voltage rectifier. The full-wave voltage doubler shown in Fig. 3 has been redrawn for greater clarity; it has better regulation than a half-wave ver- sion, and is easier to filter. The circuit produces nearly double the peak AC voltage of 170 volts, or about 340 volts peak across R L . For the first half-cycle (a), D2 is cut off and Dl conducts, so that V C1 equals approximately 170 volts DC. On the next half- cycle (b), the positive voltage is replaced by a negative voltage, so D2 conducts and Dl is cut off. R L goes across CI and C2 in series, effectively creating a doubled level of about 340 volts DC. Warning!! This article deals with and involves subject matter and the use of materials and substances that may be hazardous to health and life. Do not at- tempt to implement or use the information contained herein, unless you are experi- enced and skilled with respect to such subject matter, materials, and sub- stances. Neither the publisher nor the au- thor make any representation as for the completeness or accuracy of the informa- tion contained herein, and disclaim any liability for damages or injuries, whether caused by or arising from the tack of com- pleteness, inaccuracies of the informa- tion, misrepresentations of the directions, misapplication of the information, or other- wise. Unlike the half-wave voltage doubler, the full-wave version has two capacitors across R L rather than one. Whereas CI shown in Fig. 1 is cut off and unsupplied for half of every cycle, CI and C2 in Fig. 3 are supplied on alternate half cycles. When the capacitor corresponding to the diode that's cut off discharges, it can only do so through the capacitor being supplied, slightly decreasing both its current and the max- imum voltage it reaches. Measuring high-voltage DC Voltage measurements will be possible only to about the second or third stage of a cascaded volt- age doubler with most volt- meters. Beyond that, you'll need to use either a high-voltage DC meter or an external voltage di- vider for use with a standard high-impedance voltmeter (10 megohms or more). A good voltage divider that can be used for the purpose of high- voltage measurements is the RCA SK3868/DIV-1. a high-volt- age DC divider; it's used in TVs to reduce the final anode voltage go- ing to the CRT to the level re- quired for the focus voltage. It consists of resistors Rl (200 megohms) and R2 (40 megohms) in series, as shown in Fig. 4. There are three leads, one for the free ends of each resistor, and the other at their juncture. If you put both a 10-megohm meter (shown as 2 M in Fig. 4) and a 2.7- rnegohm resistor (R3) in parallel with the 40-megohm resistor c (R2), you can achieve almost ex- § actly 100:1 range multiplication, ^ for a full-scale deflection of 20 -» kilovolts DC. <2 61 CO o o w Q Q < EC FIG. 1— HALF-WAVE VOLTAGE DOUBLER. During the first halt-cycle [a), D1 con- ducts, D2 cuts off, C1 charges to 170 volts peak, and C2 discharges through R L . For the second half-cycle (□), the Input polar- ity is reversed, and both the input and CI are in series, producing 340 volts peak. Now D1 cuts off while D2 conducts, and the current divides between C2 and R L ; the cycle then repeats. iTT^T — V 120VACS!H£18VAC jfc C1 1 , 25VDC 4- K'OVAC -M- D1 18VAC 3fc CI 01 120VAC •>— Q + ci 25VDC ^0- 25VDC FIG. 2— TWO HALF-WAVE RECTIFIERS, one with a positive output (a) and one negative (o), combine to make a full-wave voltage doubler (c). Cascaded voltage doubters Figures 5-8 show four addi- tional voltage doublets. The one shown in Fig. 5 is the most straightforward. If you build it, use 1N4007 diodes with peak in- verse voltage (PFV1 ratings of 1 kilovolt for D1-D6, and 0.068-0.1 jxF capacitors with working voltages of 400 volts DC. Figure 5 is electrically identical to the one in Fig. 6, so keep that in mind if you should come across either format. Figure 7 shows an extended version that's better C2 DISCHARGES SLIGHTLY, IF PREVIOUSLY CHARGED + — 120VAC -O— ^ t D1 170V5SC1 ^02 170V ;£c2 t t ^?*-rr C1 DISCHARGES SLIGHTLY. IF PREVIOUSLY CHARGED FIG. 3— FULL-WAVE VOLTAGE DOUBLER, redrawn for greater clarity. For the first half- cycle (a), D2 is cut off and D1 conducts, producing about 170 volts DC across C1. On the next half-cycle (b). D2 conducts and D1 is cut off. The output voltage is now across C1 and C2 in series, doubling the level to about 340 volts DC. HV (RED WIRE) fl HVDC TV CRT FOCUS DIVIDER RCA PART #SK3868/DIV-1 r @l WHITE - WIRE R1 2O0MEG -WV R2 40MEG R3 2.7MEG —WW 10MEG KQ^l BLACK WIRE V DC VOLTMETER FIG. 4— TO MEASURE HIGH VOLTAGES with an ordinary 10-megohm meter, you can use the RCA SK3868 DIV-1 high-volt- age divider. The circuit provides a 1:100 voltage division, allowing 20 kilovolts to be measured on a 200- volt scale. FIG. 5— THIS CASCADED DOUBLER uses 1N4007 diodes rated at 1 kilovolt PIV, and capacitors from 0.068-0. VF with a 400- volt DC working voltage. stabilized for moderate-current applications; it's called either a Cockcroft -Walton or Greinacher cascaded voltage doubler. You can use a sewing needle as an emitter for the doubler shown in Fig. 8 to generate "corona wind." That will sound like a his- FIG. 6— THIS VOLTAGE DOUBLER is the same as the one shown in Fig. 5, although it's drawn differently. You should be able to recognize both versions. sing noise. (We'll shown you how to demonstrate the "wind" later on.) The circuit delivers 3.75 kilovolts DC when powered from 120 volts AC, or 7.5 kilovolts DC when powered from 240 volts AC. The output of a cascaded volt- age doubler should be termi- nated with at least 200 megohms, and only then be al- lowed to extend beyond a protec- tive plastic case, for safety. Voltages as high as 5 megavolts DC have been generated using 62 cascaded voltage doubters, es- pecially when operating in a pres- surized atmosphere. The biggest advantage to using voltage dou- blers is that they use inexpensive low-voltage parts. Otherwise, if all the parts had to be of the high- voltage variety, you would have to use expensive and rather large capacitors like the one shown in Fig. 9. If you have problems with the circuit in Fig. 8 (or any other high- voltage circuit), you must discharge every capacitor (we'll tell you how in a minute) before you check for malfunctions. When examining the circuit for problems, closely check the sol- der connections, and then the di- ode directions and continuity. The 1N4007S should have a re- sistance of 1.1K when forward- biased and be open when reverse- biased, while the capacitors FIG. 7— THE COCKCRO FT- WALTON, or Greinacher cascaded voltage doubler. has improved performance tor moderate- current applications. should all have infinite resis- tance. To properly discharge capaci- tors, build a discharging wand like the one shown in Fig. 10. Use a 2-foot wooden (or plastic) dowel, and connect a stiff wire tip 91 '"^PT If T f 1/ »<^# J FIG. 9— HIGH- VOLTAGE CAPACITORS. A 0.25 }xF, 7.5-kilovolt capacitor is on the left; a 100 pF, 15-kilovolt capacitor is in the middle; and 0.0005 hF. 5-kilo volt capacitor is on the right. powa FIG. 10— A HIGH-VOLTAGE GROUNDING wand is used to discharge capacitors. A 2- foot wooden dowel is attached to a stiff wire tip. The metal tip must be connected to an earth ground, such as a cold-water pipe. FIG. 11— HOMEMADE SWITCH for high- voltage DC. The line filter at left is a safety measure to keep high-voltage DC out of the house wiring. FIG. 12— A TYPICAL CASCADED voltage doubler. Note the wide spacings between the diodes, the long connecting wires, and the smooth solder joints. FIG. 13— THIS IS THE DOUBLER from Fig- ure 12, after being sealed in candle wax. For better protection, you can immerse it in pure paraffin oil. (piano wire works well) to a cold water pipe as earth ground with a good electrical connection. Dis- charge all capacitors twice, since they generally either hold charge, or tend to recharge from other capacitors. Don't use an AC line ground or chassis ground in- stead of an earth grounded water pipe, or you may blow a fuse or damage parts. Figure 11 shows a switch for high-voltage DC that you can use with any of the cascaded voltage- doublers shown here: standard switches may present a shock hazard. Also, use an electromag- netic interference (EMI) line filter like the one seen at left in the photo to keep high-voltage DC out of house wiring, and to pre- vent shock from static charge. The EMI filter is from Oorcom Corp. (1600 Winchester Road, SEWING NEEDLE AS EMITTER mSmfp ELECTR0DE ZUUMtt. F0R CORONA WIND 3.75/7.5WDC D1-D26:1N4007, 1kV PIV C1-C26:,068-.1nF.400VDC FIG. 8— THIS 2 5- STAGE VOLTAGE DOUBLER will generate "corona wind." It delivers 3.75 kilovolts DC when powered from 120 volts AC, or 7.5 kilovolts DC when powered from 240 volts AC. > c © c V) CD 63 FIG. 14— CORONA WIND DEMONSTRATION. The flame will deflect toward the ground plate. Note the black ground wire attached near the screw threads. When you build a cascaded voltage doubler, you can encase the circuit in pure paraffin oil or candle wax to reduce the chances of getting shocked. It will also minimize corona loss, so the high-voltage DC arrives where it's needed. Figures 12 and 13 show a typical ladder-type voltage dou- bler before and after being sealed in wax. c Q C CO m (5 67 Gaussian surface enclosing a charge q, as in Fig. 5-a. Divide the surface into an infinite number of infinitesimal surface areas ds. Area is a vector because it has a magnitude and also a di- rection, or orientation in space which is taken as normal (per- pendicular) to the surface, and pointing outward away from the enclosed volume. Each infi- nitesimal area is essentially a small plane with an E vector through it. Because the surface is arbitrary, each ds and its E vec- tor does not have to be parallel. In other words, E may not be nor- mal to the plane. To find the apparent outflow, we need to consider only the com- ponent of E normal to the plane; the rest is just flowing over the surface. The scaler, or dot prod- uct, Eds. does that by giving the product of the magnitude of E parallel with ds times the magni- tude of ds. That is the same as the product of the magnitude of the effective area (the projected area with ds parallel to E) times the magnitude of E. The appar- ent flow is electric flux. Summing the contributions from each ds over the entire surface gives the total flux kfi=/E-ds(N/Cm2) \]i is proportional to the charge q within the volume since E is pro- portional to q. Because E obeys the 1/r 2 law, and the effective area obeys the r z law, \\> is independent of the surface. If a number of point charges were contained in- side the volume, tji would be pro- portional to the total charge w o z o QC h- O LU o □ < 68 because the total E field is the linear superposition of their E fields. The proportionality con- stant is l/e , therefore Charges outside the volume would not contribute to the E field. The reason for that is if some E came tn through some ds's, it would go out through some other ds's in just the right amounts to cancel out because of the 1/r 2 and r 2 dependence. Graphically, lines having the di- rection of E at each point, and with their closeness proportional to i|/ are sometimes used to depict the E field. That's a convenient approach, but it must be remem- bered that the E field is actually a vector at each point in space. If the Gaussian surface shrinks down to a point, then all the ds's would shrink to zero and so would flux ty. The ratio of the change in flux to the change in volume as the surface shrinks reaches a limiting value. That limiting value is called the diver- gence, and is symbolized by V-E=d»(./d volljme That must be proportional to the charge per unit volume dQ/dvoinma = p, which is called charge density within the surface, therefore V-E = p/e D (N/Cm) Since e is a constant and is inde- pendent of the volume, the above equation could be written as V eo E = p A number of E field instruments (small +q's) scattered around a region, would diverge away from a positive charge (a positive di- F16, 5 — CHARACTERISTIC OF AN E FIELD. In (a) a Gaussian surface composed of an infinite number of infinitesimal areas d„ surrounds a positive charge q. The total apparent flow of the electric field and the electric flux is the sum of Ed s over the entire surface, which is proportional to q. Flux from charges outside the surface does not contribute because whatever flux "flows" through the surface must also flow back out. In (b), an amperean loop composed of an infinite number of infinitesimal lengths, dl, encircles the charge. The electric circulation around the loop JE-d, is zero. vergence) or converge upon a negative charge (a negative diver- gence). A field with zero diver- gence cannot start or end at the point. The apparent rotation of the E field around a point can be mea- sured by imagining an arbitrary closed curve, called an amperean loop, of length 1, encircling a charge q as in Fig. 5-b. Divide the loop into an infinite number of infinitesimally small lengths, dl. The direction of dl is taken as counter-clock wise. A loop is used because the dl's define general di- rections around q, whereas for a surface, the ds's define general directions away from q. Each dl is so small that it is essentially a straight line segment with an E vector through it. The apparent rotation at each dl is the magni- tude of the component of E, par- allel to dl times the magnitude of dl. We must again use the dot product E-dl to allow for the fact that E may not be parallel to dl. That gives the magnitude of the E component parallel to dl times the magnitude of dl. Imagine moving around the loop, summing up E-dl to obtain the total apparent rotation, or electric circulation. Since E points radially along r, the only place E-dl is non-zero is where dl has a component parallel to r. But the entire loop is closed, so for any amount it moves out radi- ally, it must at some place move that same amount inward. The field is symmetrical, therefore whenever E-dl is positive along some dl's, it is negative by the same amount along other dl's, with a net result of zero. In cal- culus notation fE-dl = The circle on the integration symbol reminds us that the loop is closed. Again, by linear super- position, that is true for any stat- ic charge configuration. If the amperean loop shrinks down to a point, all the dl's would shrink to zero, and so would ° J"E-dl (even if it weren't already zero). But the ratio of the change in jE-dl to the change in the enclosed area as the loop shrinks reaches a limiting val- ue. That limiting value is called the curl, and is symbolized by vxE=d(fE-dl)/d afea . The curl is a vector, since area is a vector. It's direction is taken as continued on page 79 Focused X-ray breakthrough, C-60 and the new Buckyballs, electric power research info, getting telephone information, and caller number delivery secrets. Let us start off with a few up- dates to the infrared people detectors we looked into a col- umn or two ago. It seems Amperex/ Phillips decided to jump ship and abandon their line of IR detectors, Their great ap notes seem to have been discontinued. Several remain- ing pyroelectric detector chip sam- ples are supposed to still be available through their sales support line (401-762-3800). On the other hand, people detec- tors have suddenly become a low- cost commodity. So much so that it is now usually cheaper to buy retail and modify, rather than building your own motion sensor up from scratch. Es- pecially when you factor in the critical Fresnel lens design. One cause for the sudden price drop is a new Cali- fornia law which mandates these on nearly every light switch in new office building construction. Herbach and Rademan offers a great ready-to-install infrared people detector as #TM90SE1491 for $12.50. And the Heathkit folks have several new occupancy and intrusion detector variations in their free home- security electronics catalog. Or, you might also want to check your local price club or warehouse builder's supply outlet. A reminder that we have a great help line available for tech questions, off-the-wall networking, and useful consultant referrals. All per the box below. And please remember that we are using California time during the summer. Those 4:30 AM calls tend to get just a tad old. And please, please carefully read the entire column, es- pecially the Names and Numbers sidebar. Oh yeah — please note the French mathematician's name is "Fre'-nell," not "fresh-nell." And. of course, the correct pronunciations found on our ongoing voice helpline are "hee-lah" and "ten-ah-hah." Our biggie for this month involves telephone caller identification chips and standards. But, first, let's find out how you go about... Getting telephone information Contrary to popular belief, it's real easy to get full technical details on nearly everything that involves the telephone company. All you have to do is ask them. There is a great publication known as the Bell System Technical Journal that has been around for over 60 years now. Included are full details on just about everything involving tele- phone hardware and software. Check almost any large technical library for your access. There's also the Bell System Record, but it focuses more on nontechnical policy issues. For ongoing telephone standards and tutorial information, start out with the no-charge Bellcore 1991 Catalog of Technical information. Then order the individual papers you want. These do tend to be a tad on the pricey side, with $20 to $90 being typical. VISA orders are accepted with one-week delivery. Sorry, but I don't know of any library that has a full set of these to loan out. Please let me know if you find a lower-cost access source. The library obviously screams to be made available on CD ROM. Caller number delivery Most of your telephone operating companies are now in the midst of upgrading to a totally digital system that includes a number of new CLASS services. By far the most popular new service is known as NEED HELP? Phone or write your Hardware Hacker questions directly to: Don Lancaster Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 Caller Number Delivery, which can show you who is calling you before you pick up your telephone handset. Caller number delivery does ap- pear rather controversial. But, for most people most of the time, know- ing who is calling you is infinitely more important than protecting people's "rights" to make undetected obscene phone calls. Very sadly, at least one state (Pennsylvania) has stupidly banned this wonderful new service. In other areas, the caller is given the option of blocking their call- er ID, for those one-in-a-thousand calls when your anomynity might le- gitimately be desired. Maybe for a drug overdose hotline. Blocking can get done by entering a three-digit code before you make your call. So what is caller ID. and how does it work? Figure 1 shows you some of the more interesting Bellcore documents that involve caller ID. But the key horse's-mouth paper you'll need is Technical Reference TR-TSY- 00030 and titles SPCS Customer Premises Equipment Data Interface. The cost is $25 via VISA. Figure 2 shows you the exact placement of the tone codes. Caller number delivery is normally provided as a code burst between the first and second full rings while your phone is still on its hook. Enough delay is pro- vided to allow for the short half-sec- ond breaks sometimes involved in selective ringing. After your first full ring gets de- tected, a data path is established. A data path is simply any method of receiving some modem tones. The ID tones are then routed to suitable cir- cuitry to recognize the data burst and strip out the needed information. The format and codes are related to the digital codes used in pagers. The tones sent out are plain old c serial binary modem tones at 1200 § baud. A digital logic one (or a mark) is <$ defined as one cycle of a 1200- Hz ^ sine wave. A digital logic zero (or a ^ 69 w o z g F o I space) is defined as nearly two cy- cles of a 2200-Hz sine wave. Each eight-bit character is preceded by a space start bit and a mark stop bit. The transmitted signal level is -13.5 dBm. While the code trans- mission is asynchronous, phase co- herence is preserved throughout the entire caller ID message. No more than 20 marks are permitted between characters. Figure 3 shows you the data for- mat. It might appear fairly compli- cated at first, but making sure the number is valid is quite important. Al- most certainly, you will elect to use a computer, or at the very least, some simple microcontroller in your caller- ID display circuitry. The first thing sent is called the channel seizure signal. That consists of 30 bytes of a Hex $55 code. After decoding, another way to look at this "hey wake up!" signal is one quarter second of a 600-Hz square wave. After the channel seizure signal, a carrier signal is sent. It's used to con- dition your receiver for valid data. The carrier consists of at least 1 50 millise- conds worth of marks. After the de- coding, you have a one-sixth second 1. NYNEX Catalog of Technical Information, #NIP-7400, Free, 2. SPCS Customer Premises Equipment Data Interface, #TR-TSY-0030, $25 3. CLASS Feature: Calling Number Delivery #FSD-02-1051 . $30. 4. CLASS Feature: Calling Number Delivery Blocking #TR-TSY-000391, $33 The main Bellcore service number is (800) 521 -CORE, Of these resources, (2) is by far the most important. FIG. 1— HERE'S THE KEY INSIDER SECRET PAPERS involved with telephone system caller number delivery. CALLER ID TONES FIRST RING SECOND RING FIG. 2— THE CALLER ID DATA BURST is sent between the first and second rings as shown. The transmitted level is -13 dBm and enough delay is provided to allow for distinctive ringing patterns. A typical number ID will take half a second. The phone must remain on hook while the ID is being received. CHANNEL SEIZURE SIGNAL CARRIER SIGNAL MESSAGE TYPE WORD MESSAGE LENGTH WORD DATA WORDS CHECK SUM WORD r NEW FROM 1 DON LANCASTER HARDWARE HACKER STUFF Hardware Hacker Reprints II or 111 24.50 Midnight Engineering Reprints 16.50 Incredible Secret Money Machine 12.50 CMOS Cookbook 24.50 TTL Cookbook 19.50 Active Filter Cookbook 19.50 Micro Cookbook vol t or II 19,50 Lancaster Classics Library 109.50 Enhancing your Apple I or II 17.50 AppleWrller Cookbook 19.50 Absolute Reset lie & lie 19.50 Enhance 1 or II Companion Disk 19.50 AppleWrlter CB or Assy CB Disk 24.50 POSTSCRIPT STUFF Ask The Guru Reprints 1, tl or III 24.50 LaserWriter Secrets (lie-Mat.-: PC) 29.50 PostScript Show & Tell 39.50 Intra to PostScript VHS Video 39.50 PostScript Beginner Stud 39.50 PostScript Cookbook (Adobe) 16.50 PostScript Ret. Manual (Adobe) 22.50 PostScript Program Design (Adobe) 22.50 Type 1 Font Format (Adobe) 15.50 LaserWriter Reference (Apple) 19.50 Real World Postscript (Roth) 22.50 PostScript Visual Approach (Smith 22 .50 Thinking In PostScript (Re id) 22.50 The Whole Works (all PostScript) 29S.50 FREE VOICE HELPLINE VISA^MC SYNERGETICS Box 809-RE Thatcher, AZ 85552 (602) 428-4073 J The | CHANNEL SEIZURE SIGNAL | is made up of a string of 30 bytes of Hex $55, and Is equivalent lo 250 msec, of a 60D Hertz square wave. The | carrier siqnal| consists of — ' 150 mlllseconds of marks, equal to digital logic ones. The | messaqe type word] is a" Hex $04 when providing for the identification of a catling number. The | checksum word | is the twos-complement 8-bit sum of the message length and data words. It can be used for error trapping. -The | data words] are the actual caller ID digits in ASCII character form, least significant digit first. Each digit byte Is preceded by a zero "space" start bit and followed by at least one "mark" stop bit The | MESSAGE LENGTH WORD the number of characters being provided as the calling number. FIG. 3— THE DATA FORMAT for the caller ID service. solid string of logical ones following your quarter-second burst square wave at 600 Hz. Your caller-ID receiver circuitry is supposed to use this "wake up call" and string of marks to prepare itself for valid data reception. After setup, the first valid data byte is called a message type word. If that burst is for the caller number delivery, your message type word will be a hex $04. Other codes could get used for other purposes. For instance, a hex $0A means "message waiting" for pager applications. The next byte is called the message length word that tells you how many digits are to be provided in the caller ID numbers that are to fol- low. The message length does not include itself or the checksum in its count. The actual ASCII characters for the caller phone number follow starting 70 NAMES AND NUMBERS Bellcore 445 South Street, Room 2J-125 Morristown, NJ 07926 (201) 829-4785 CIRCLE 301 ON FREE INFORMATION CARD Communications Specialists 426 West Taft Avenue Orange, CA 92665 (800) 854-0547 CIRCLE 302 ON FREE INFORMATION CARD Dialog Information Services 3460 Hillview Avenue Palo Aito, CA 94304 (415) 858-2700 CIRCLE 303 ON FREE INFORMATION CARD Electric Power Research Ins. 3412 Hillview Avenue Palo Alto, CA 94304 (415) 855-2000 CIRCLE 304 ON FREE INFORMATION CARD GEnie 401 North Washington Street Rockville, MD 20850 (800) 638-9636 CIRCLE 305 ON FREE INFORMATION CARD Herbach & Rademan 401 East Erie Avenue Philadelphia, PA 19134 (215) 426-1700 CIRCLE 306 ON FREE INFORMATION CARD Mouser Electronics 11433 Woodside Avenue Santee, CA 92071 (800) 346-6873 CIRCLE 309 ON FREE INFORMATION CARD National Semiconductor 475 Ellis Street Mountain View, CA 94043 (213) 323-3923 CIRCLE 310 ON FREE INFORMATION CARD Power Quality 2742 Eastman Avenue #33-34 Ventura, CA 93003 (805) 650-7070 CIRCLE 311 ON FREE INFORMATION CARD Satco 924 South 19th Avenue Minneapolis, MN 55404 (800) 328-4644 CIRCLE 312 ON FREE INFORMATION CARD SGS-Thomson 100 East Bell Road Pheonix, AZ 85022 (602) 867-6259 CIRCLE 313 ON FREE INFORMATION CARD Sierra Semiconductor 2075 North Capitol Avenue San Jose, CA 95132 (408} 263-9300 CIRCLE 314 ON FREE INFORMATION CARD There are a number of caller ID devices commercially available, with pricing in the $60 to $500 range. Typ- ical are the Allied incoming call identi- fier, the Bellsouth calling line identifier, the Cidco Slimline series, and the TC-1021. TC-1080, and the TC-1082. One discount source of all these is VSI Telecommunications. Do note that your caller number delivery service must be provided to you before you can use any of these devices. If the code is not being sent, there is no way you can receive it. There might be certain state laws pro- hibiting their use as well. That, of course, can be cured by staking your state representative to the nearest anthill. Finally, anything you connect to the telephone line has to be FCC Type 68 approved. Meeting the rules for type approval is fairly reasonable and simple. But the approval process itself is a bear. We do have several experimental caller ID projects in the works here at Radio-Electronics, along with some simulator and test software. But there are ongoing problems with service availability, with meeting FCC part 68 specs, and in keeping the price low enough. Probably some ab- solute minimum general purpose call- er ID interface kit that demands use of a personal computer programmed in machine language to develop your own circuits makes the most sense at this time. Let us know what you want to see here, Materials & Electrochem Res. 7960 South Kolb Road Tucson, AZ 85706 (602) 574-1980 CIRCLE 307 ON FREE INFORMATION CARD Meridian Data 5615 Scotts Valley Drive Scotts Valley, CA 95066 (408) 438-3100 CIRCLE 308 ON FREE INFORMATION CARD with the least significant digit. For in- stance, a digit "2" should get ASCII coded as hex $32. Your message ends with a checksum word used for optional er- ror detection. The checksum is the two's complement of the 8-bit sum of the message type word, your mes- sage length word, and the number of data words provided. To provide an error detection, you run your own 8- bit sum of all the bits of all the data Synergetics Box 809-RE Thatcher, AZ 85552 (602) 428-4073 CIRCLE 315 ON FREE INFORMATION CARD VSI Telecommunications 9329 Douglas Drive Riverside, CA 92503 (800) 999-8232 CIRCLE 316 ON FREE INFORMATION CARD words, and then add the checksum to it. If there are no transmission or re- ception errors, you should get a zero result. A non-zero result means an irrecoverable error. I've just described the single data message format to you. Some nasty complications can arise if you have multiple data messages or several CLASS services active, such as call waiting. See the Bellcore info for fur- ther details. A caller-ID chip As Fig, 4 shows us, there are usu- ally four stages to the caller ID receiver. The first stage is called an FCC Part 68 Interface. That is needed to safely and legally connect to your phone system. Full details on Type-68 interface secrets appear in the Hardvsare Hacker //reprints. The second stage is the analog front end. The analog front end pro- vides filtering and amplification, and converts al! of your tones into actual TTL ones and zeros. Figure 5 shows you an analog front- end circuit that uses the brand new Sierra Semiconductor SC11211N caller-ID chip. You input the low- level telephone tones and get out a serial data stream ready for computer or c microcontroller interpretation. Inside ^ the chip is a fancy filter, an energy ¥\ detector, a tone demodulator, and a ^ clock. An ordinary TV color crystal 2 71 and four capacitors is all you need to use this circuit. Cost for the 16-pin mini DIP is in the $4 range in small quantities. There's also a fancier SC11210 chip fabricated in a smaller package that deletes the internal crystal os- cillator, the level setting, and all of the energy-detection features. Sierra also has ap notes on suitable FCC part-68 interfaces. While these chips are low in cost and work rather well, note that they are only analog front ends. "AH" they do is reliably accept low-level tones from the part 68 interface and then convert them into a string of digital ones and zeros. The third ID stage is the number extractor. The number extractor takes the serial data stream, makes sure it's valid, and then extracts and formats the calling number. The number might also be displayed. The number extractor almost has to be a computer or microcontroller, since it probably would be unbearably com- plicated and expensive otherwise. The final and optional stage is any "gee whiz" stuff. Things like looking up the actual name of the caller. Or pulling their sales or service records. Or keeping a full record of the last hundred calls. Or interacting with a humongous CD-ROM data base. Once again, be sure to let us know what you want to see in the way of further caller-ID projects. w o z o DC r- O 6 □ < PHONE LINE T 1 FCC PART 68 INTERFACE Meets the legal requirements lor accessing signals olt ol Ihe telephone network. ANALOG FRONT END Converts the low level tones into serial digital logic ones and zeros. NUMBER EXTRACTOR Converts the serial data stream into numbers that can be displayed. GEE WHIZ STUFF Does value added features such as changing numbers to actual names. CALLING NUMBER DISPLAY TONE INPUTS FROM PART 68 INTERFACE O CALL PROGRESS INPUT -O SERIAL DATA OUTPUT O ENERGY DETECT OUTPUT 58 Mhz Xtal 0.1uF FIG. 5— A CALLER ID ANALOG FRONT END that uses the Sierra Semiconductor SC11 211 chip. Low-level tones are accepted from the FCC Part 68 interface and get converted into serial ones and zeros for further digital processing. FIG. 4— THE FOUR STAGES INVOLVED in a calling number ID display. Buckyballs and C60 Carbon is one of the more interest- ing chemical elements. It forms the basis of all life as we know it. And, because of some energy and bonding restrictions, carbon quite possibly will also turn out to be the basis of all life as we don't know it. Carbon is also the key to most fuels, plastics, and foods. It bonds readily with many other elements, creating by far the richest assortment of useful chemical compounds. Until recently, there were only two known forms for any pure carbon molecules. These were the supersoft graphite and superhard diamond. But several chemists (Kroto, et al. Nature v318 p162, 1985) have discovered a uniquely bizarre third form of carbon molecule. By taking 20 hexagonal groupings of six carbon atoms and then fusing them properly with 12 pentagonal groupings of five carbon atoms, a hollow geodetic pure-car- bon molecule consisting of 60 atoms gets created. Since this hollow all-carbon C-60 molecule looks like a geodetic dome or a soccer ball, they were promptly given the name of Buckyballs. named after the late Buckminister Fuller, a leading early proponent of geodetic dome structures. Initially a few C-60 molecules were painfully hand collected, measured, and tested. And, sure enough, C-60 is for real. An experimental proof of the Buckyball shape has just recently appeared CHawkins, et al., Science, v252, p312), along with a very fine bibliography. After the discovery, several other chemists (Kratschmer, et al. Nature v347 on p354, 1990) were playing around with carbon rods in a plain old arc welder and figured out how to make lots of Buckyballs in a process almost as complicated as smoking a piece of glass with a candle. As a result, the price of Buckyballs has plummeted to an astonishingly low $1200 per gram. Quantity pricing is even less, and 100 milligrams of Buckyballs are available for $250 if you are on a limited budget. You can get all the Buckyballs you want off the shelf from Materials and Electro- chemical Research. The latest games include putting Osmium "handles" on a Buckyball to make them easier to align, and adding precise doping impurities to create several new families of "Dopey balls." While nobody has yet come up with a proven commercial use for Buckyballs, they are now by far the hottest topic in physical chemistry. Buckyballs will even superconduct, although only at rather low tempera- tures so far. The hollow molecule sug- gests all sorts of stunning new possibilities which include super lu- bricants, new batteries, ultra-strong fibers, improved semiconductors, and entire new classes of materials and compounds. Needless to say, Buckyballs are a sure-fire winner for a Science Fair topic or school research paper. And we here at Radio-Electronics would certainly be most interested in any Buckyball project that's even re- motely related to electronics. Let us know what you can do here. Ongoing info on Buckyballs will ap- pear in those Science and Nature 72 New! NRI course in Cellular Telephone Installation and Servicing prepares you to succeed in today 's fastest-growing communications field Now you can get the skills you need to cash in on today's booming cellular industry as you install and test your own state-of-the-art cellular telephone. Cellular business is big business! In the few short years since the first commercial cellular telephone system went on-line, over 1,000,000 people have signed up for service in more than 120 cities nationwide. Today, the industry is growing at an incredibly fast 4% a month, and experts predict that by 1991, at least 85% of the United States will be * covered for cellular service. Better \ yet, by 1993 total industry revenues will exceed $10,000,000,000-making cellular the fastest growing electronics communications field today. For you, that means extraordinary career and money-making opportunities Get a fasr start today with NRI's hot new course in Cellular Telephone Installation and Servicing. See how far you can go! lO-digit luminescent display with 24-digit number entry/review Help wanted! Urgent demand for field technicians who can install and test new cellular telephone equipment! Get the skills, knowledge, and confidence to install and test cellular telephone equipment, and you can name your price in this exploding new job market, Cellular system developers, retailers, and service providers— all on the ground floor of an industry that's still so young and growing so fast— are all willing to pay a premium for anyone trained to service this brand-new equipment. Now, with NRI, you can take full advantage of ever}' exciting opportunity in today's— and tomorrow's— booming field of cellular communications. Exclusive hands-on training includes high-performance mobile cellular telephone you keep Your NRI course starts with the electronics fundamentals you need to understand and service all telephone systems, then walks you step by step through the installation, troubleshooting, and repair of popular telephone systems in use today But that's just the beginning. With a solid conventional phone servicing foundation behind you, you're ready to build your expert understanding of the cellular telephone systems moving fast into communities all over the U.S. Following complete, easy-to-read guidelines, you install a full- featured mobile cellular telephone in your own car, then take it through a series of diagnostic tests to become fully acquainted with its operating functions. Best of all, if you live in an area already offering Ignition sense automatically turns your phone on and off with car's ignition Electronic lock prevents unauthorized use of your phone 22 memories including last number called Super speed dialing and 1 digit recall cellular coverage, NRI will help you actually go on-line with up-to-date, expert advice on choosing the best and most affordable cellular service available. Send for your FREE catalog today For all the details about NRI's exclusive new training, send the coupon today You'll receive a complete catalog describing NRI's Cellular Telephone Installation and Servicing course plus NRI courses in other high- tech, in-demand fields. If the coupon is missing, write to NRI School of Electronics, McGraw-Hill Continuing Education Center, 4401 Connecticut Avenue, Washington, DC 20008. Send Coupon Today For Free Catalog! ■iniM ImmsWM School of Electronics McGraw-Hill Continuing Education Center ■ 4401 Connecticut Ave, Washington, DC 20008 . 81 CHECK ONE CATALOG ONLY | □ Cellular Telephone n Computer Electronics Q TV/Video/Audio Servicing D Electronic Music Technology approved under Gl Bill □ check tor details. □ Data Communications □ Security Electronics D Robotics D Basic Electronics Name . .Age_ Street City/State/Zip Accredited Member National Home Study Council 3-081 > c O c en 75 magazines, and, of course, through the Dialog information System. EPRI The Electric Power Research In- stitute is a rather low-key research consortium. You have to be a power company to join them. Even then, their annual membership fees are as- tronomical. But, with their $400 mil- lion annual budget they now do all sorts of top-quality energy research, including thorough coverage of such subjects as solar power, efficient lighting, cogeneration, conservation, environmental quality, cold fusion, and alternate energy sources. Plus, of course, nasty old nuke stuff. EPRI does have plenty of videos, technical reports, papers and such available. They also have products for licensing. The summary report of most of their recent key papers costs $45. You might like to contact them directly for further info. New tech literature A new method of focusing X-rays known as a Kumhakov lens is now described on page 208 of Science volume 252. If it proves as good as it looks, this could revolutionize every- thing from high-density integrated cir- cuits to safer dentistry. The lens consists of scads of glass capillaries, and the X-rays skip along the sur- faces at low angles, rather than shooting right on through them. From National Semiconductor, a new General Purpose Linear Devices data book. And from SGS-Thomson a new Power Transistors Application Manual. Good stuff. Satco is a great source for oddball tools and supplies. They usually sell to those school vocational education programs. They do have a great new thousand-page catalog available. Unusual scientific images of all sorts of geologic, oceanographic and atmospheric stuff is available on a GRIPS-2 CD-ROM from Meridian Data. It is part of a new program to release obscure government re- search to a wider audience. Our unusual trade journal of the month is Power Quality, aimed at the higher-end users of uninteruptable power supplies. Chip capacitors and resistors for surface mounting are now finally be- coming widely available in small quan- tities at sane pricing. While Mouser Electronics is a good source, some ready-to-go $49.95 resistor and ca- pacitor kits are available through Communications Specialists. That's three cents each for the resistors and fourteen for the caps. Turning to my own products, for the fundamentals of digital integrated cir- cuits, do check out my TTL Cook- hook and CMOS Cookbook. Or you can pick up all of those "oldies but goodies" all at once in my Lancaster Classics Library. I also have a BBS up as GEnie PSRT. Besides all the PostScript and desktop publishing stuff, you'll find all sorts of ongoing Hardware Hacker and Midnight Engineering resources here. You can get yourvoice connect info by dialing (800) 638-9636. We also now have the Hardware Hacker ill, Ask the Guru III, and the new Midnight Engineering I reprints available, which have the latest and best of all these columns in them. All edited, revised, and indexed. Finally, I do have a new and free mailer for you that includes dozens of insider hardware hacking secret re- sources. Write or call for info. Our usual reminder here that most of the items mentioned appear in the Names and Numbers sidebar. R-E o z o rx & LU 6 o < 76 r FCC NO-CODE ' AMATEUR RADIO LICENSE The FCC recently passed Docket 90- 55 which for the first time allows a new codeless entry ham radio license of technician grade. Privileges 30 MHz and above — All modes! (See R.E, ar- ticle in April 1991 issue). Get all the no-code license details, study & testing information plus a one- year subscription to one of ham radio's longest running specialty mode publi- cations that will teach you all about the new modes you will be able to operate! FSTV SSTV FAX RTTY PACKET AMTOR OSCAR FM REPEATERS MICROWA VEAND LOTS MORE! SEND $25 CHECK OR MONEY ORDER f" siWJCo'M j OUR 24TH YEAR SINCE 1967! I The SPEC-COM Journal P.O. Box 1002, Dubuque, IA 52004 (319)557-8791 MCVISA (5% added) m Be an FCC LICENSED ELECTRONIC TECHNICIAN! Earn up to $30 an hour and more! at home in spare time, o previous experience needed! No costly school. No commuting to class. The Original Home-Study course prepares you for the "FCC Commercial Radio- telephone License."This valuable license is your professional "ticket" to thousands of exciting jobs in Communications, Radio- TV, Microwave, Maritime, Radar, Avionics and more. . .even start your own business! You don't need a college degree to qualify, but you do need an FCC License. Mo Need to Quit Your Job or Go To School This proven course is easy, fast and low cost! GUARANTEED PASS— You get your FCC License or money refunded. Send for FREE facts now. MAIL COUPON TODAY! r commdnD VRODucfiofis" " 1 FCC LICENSE TRAINING, Dept. 90 P.O. Box 2824, San Francisco, CA 94126 Please rush FREE details immediately! ADDRESS . CITY LEAIIN VCK CLEANING/MAINTENANCE/REPAIR EARN UP TO $1000 A WEEK.WORKING PART TIME FROM YOUR OWN HOME! THE MONEY MAKING OPPORTUNITY OF THE 1990S IF you are able to work with common small hand tools , and are familiar with basic electronics (i.e. able to use voltmeter, understand DC electronics), . . , IF you possess average mechanical ability, and have a VCR on which to practice and learn. . . .then we can teach YOU VCR maintenance and repair! FACT: up to 90% of ALL VCR malfunctions are due to simple MECHANICAL or ELECTRO-MECHANICAL breakdowns! FACT: over 77 million VCRs in use today nationwide! Averagp VCR needs service or repair every 12 to 18 months! Viejo's 400 PAGE TRAINING MANUAL (over 500 pho- tos and illustrations) and AWARD-WINNING VIDEO TRAINING TAPE reveals the SECRETS ot VCR mainte- nance and repair — "real world" information that is NOT available elsewhere! Also includes all the into you'll need regarding the BUSINESS-SIDE of running a successful service op- eration! pREE | HFuR mation CALL TOLL-FREE 1-800-537-0589 Or write to: Viejo Publications Inc. 5329 Fountain Ave. Los Angeles, CA 90029 Dept. RE CIRCLE 176 ON FREE INFORMATION CARD DRAWING BOARD A PC board for our audible logic probe. ROBERT GROSSBLATT Some things are enjoyable and some things aren't. This is true in life and it's just as true in electronics. Going through the whole process of a design — from idea to paper to breadboard — is a great exercise in brain stretching and a chance to let your subconscious do a- bit of work. For a lot of people (at least judging by the things I get asked about in the mail), the real hassle starts when they finish all the de- velopment work and have to come up with a final version of whatever they have on the bench. We've been spending the last cou- ple of months on the development of handy dandy bench equipment and the logic probe we just finished up is a really neat piece of gear to have around when you're working on a pro- totype circuit. Once you put it to- gether, you'll find that it's one of those things you'll always reach for first when you want to do some electron snooping. That's all well and good but, even though one measure of a tool's worth is how much it can do, another impor- tant criterion is how easy it is to use. Companies that make test equip- ment spend a lot of money designing the "user interface" since they know all too well that no matter how ver- satile their products are, if they're not convenient to use as well, people just won't buy them. The more time you spend in the electronics business, the more you'll learn that appearance and convenience is just as important as substance and power. All this is leading up to the fact that the logic probe we designed is going to be useful only if it's conveniently packaged and securely made. And that means you can't reasonably ex- pect it to be a permanent member of your toolkit unless you put it on a PC board. This is the part of the design process that most people dread. Lay- ing out a board is one of the most tedious and least enjoyable activities you'll ever come across in electronics. Because I'm a nice guy, I'm going to save you a lot of work and give you a foil pattern for the logic probe. I found the circuit so useful that I did a board for it not too long after the probe was first designed. Since it's not an overly complex circuit, it could be laid out on a single-sided board; we've printed the foil pattern here in case you want to make your own board. If you trace the circuit as it's laid out on the board, you'll see that' I made some changes to the original circuit we finished designing last time. The changes were done to make it easier to design the PC board and don't have any functional effect on the cir- cuit. Some of the comparators have been swapped and the LED's are set up differently so it was simpler to bring their leads out to the edge of the board. When I did the board a few years ago, I kept the board as small as pos- sible so it could be housed in a hand- held case. I wound up making my own case for the probe but there are sev- eral companies that make suitably sized cases. There's nothing critical about the board — none of the traces are very thin and there's plenty of room on the board to make them all at least a sixteenth of an inch thick. It's an easy board to etch with even the crudest equipment. The parts-placement di- agram is shown in Fig. 1 and the only components I haven't put on the board are the switches and the speaker. If you can find a small enough speaker, you can leave space for it on the end of the board. O PXOBB T/P /-E.D/ c 3 FIG. 1— PARTS-PLACEMENT DIAGRAM. The only components that aren't on the board are the switches and the speaker. 77 R-E Engineering Admart Rates: Ads are 2Wx2?4". One insertion $995 each. Six insertions S950 each. Twelve insertions 59Z5 each. Closing date same as regular rate card. Send order with remittance to Engineering Admart, Radio-Electronics Magazine, 500-B Bi-County Blvd., Farmingdaie, NY 11735. Direct telephone inquiries to Arline fishman, area code-1-516-293-3000. FAX 1-516-293-3115. Only 100% Engineering ads are accepted for this Admart. FCC LICENSE PREPARATION The FCC has revised and updated the commercial license exam. The NEW EXAM covers updated marine and aviation rules and regulations, transistor and digital circuitry. 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'COMMUNICATIONS SPECIALISTS, INC. 426 West Talt Ave ■ Orange, CA 92665-4296 Local (714) 998-3021 • PAX (714) 974-3420 Entire USA 1 -800-854-0547 CIRCLE 196 ON FREE INFORMATION CARD CO O Z o CZ o o D < rr The PC board is the final touch for the probe and, if you plan on using the circuit on the bench, you should give serious thought to making it. Just about the only problems you should have are the common ones that al- ways show up when you're making a board. These are things like solder blobs, bad joints, and backward com- ponents. You should use sockets for both the IC's. They add a bit to the PARTS LIST Ail resistors are 'A-watt, 5%. R1, R6, R12— 100,000 ohms R2— 39,000 ohms R3— 27,000 ohms R4— 470 ohms R5— 270,000 ohms R7-R1 0—1000 ohms R11— 10,000 ohms R13— 4700 ohms R14 — 50-200 ohms (sets audio volume) Capacitors C1 — 0.02 |xF, ceramic disc C2— 10 ixF, electrolytic C3 — 0.01 iaF, ceramic disc Semiconductors IC1 — LM339 quad comparator IC2— 555 timer D1-D3— 1N914diode LED1— red light-emitting diode LED2 — green light-emitting diode Miscellaneous: power and input leads, speaker, perforated con- struction board or PC board, wire, solder, etc. height of the board but the margin of safety they add is more than worth the extra quarter inch. The logic probe is a good example of the kind of test equipment you can build yourself that's just as useful as similar stuff you can buy in a store. There are additions that you can make to the probe that will make it even more versatile. One that I've had in the back of my mind for years is to add a pulse detector to the circuit. It's not hard to do since the probe already has a front end that can sense logic levels. I know myself well enough to be sure that I'll never get around to doing it but, while you have the circuit on the breadboard, it's a good time for you to think about doing it. I don't want to get into the details of the design but one of the first things that crosses my mind is that the heart of a pulse de- tector is a pulse generator. We al- ready have a 555 on the board and that's one of the chips of choice to use when you want to build a pulse generator. All you need is a bit of creative switching to convert the layout of the 555 on the board to a pulse generator that's triggered by the output of the comparator, if you really get into it. the natural way to go is to have the pulse detector produce two tones: one for a high pulse and one for a low pulse. If you don't want to fool around with switching the components on the existing 555, you can replace the chip with a 556 and use one side of it for the original probe and the other side for the pulse detector. If you add that feature to the probe, or if you think of something else that's particularly slick, let me know about it and I'll put it in the column. As a mat- ter of fact, well make a contest out of it and the two best modifications to the circuit will win something. I need some time to figure out what that something will be — either the usual magazine subscription or something else — but I'll let you know what it is. There's not enough room left this month to run through our next topic — a digital oscilloscope — but there is enough room for me to pass along the schematic shown in Fig. 2. It's a handy circuit that will monitor a power supply and let you know if the output voltage strays more than a half a volt away from five volts Cor whatever volt- age you set as the trigger). You'll notice that the circuit has two very similar sections. The first one, the low-voltage monitor, taps the sys- tem voltage through R3 and uses the Zener voltage to keep transistor Q1 turned on. The high-voltage monitor taps the system voltage through R4 and, until the voltage is high enough for the Zener to conduct, it keeps transistor 02 turned off. If you use multi-turn potentiome- ters, you can set the low and high thresholds just about anywhere you 78 FIG. 2— THIS CIRCUIT WILL MONITOR A POWER SUPPLY and Indicate whether the output voltage strays more than a half a volt away from whatever voltage you set as the trigger. ELECTROMAGNETICS continued from page 68 THE LOGIC PROBE CAN BE ASSEMBLED on this single-sided board. want. For standard TTL circuits, it's best to know if the voltage is more than half a volt away from five volts but, if you're really paranoid about this kind of thing, you can trim the circuit to get even closer to five volts than that. If you want to use the circuit to keep an eye on voltages that are higher than nine volts or so, it's a good idea to replace the 4-volt Zeners shown in the schematic with something higher. The exact threshold voltage of the diodes shown in Fig. 2 isn't important (anything around 4 volts is okay in- cluding the standard values between 3.3 and 4.3 volts) since the voltages seen by the Zeners are set by the two potentiometers. You can have the outputs of the circuit light LED's as shown in the schematic or, with a bit of work, they can trigger alarms, buzzers, relays, or whatever else you have in mind. If you really feel like doing some design work, you can keep the idea of a voltage monitor and throw out the circuit. Remember that you can use a comparator to do the same job. The front end of the logic probe is tailor- made for an application like this but you'll have to do some arithmetic to recalculate the resistor values to set the comparator windows and make the circuit trigger on the voltages you want to monitor. If you're not sure about how to do that, go back over the last few col- umns and you'll find a complete ex- planation of the calculations you have to do. If there's enough interest in doing this, I'll go through the math in a future column. Back issues of the magazine are probably in your local library but, if they're not, you can order back is- sues by writing to the magazine (Ra- dio- Elect r on ics Reprint Bookstore. PO Box 4079. Farm- ingdale. NY 11735). 1991 back issues are $4.00, 1990 are $4.50, 1989 are $4.75, 1988 are $5.00, 1987 are $5.25. and 1986 are $5.50. Indicate the month and year of the issue you want; if you don't want an entire is- sue, or if the one you want is not in stock, you can order copies of arti- cles for 50 cents a page. Shipping charges are $1.25 for orders up to $5.00. $2.00 for $5.01-$10.00, $3.00 for $10.01-$20.00. $4.00 for $20.01-$30.00, $5.00 for $30. 01 -$40. 00, $6.00 for $40.01-$50.00, and $7.50 for or- ders of $50.01 and up. New York State residents must add sales tax. Make checks payable to Gernsback Publications, Incorporated. When we get together next time, we'll look into digital scopes and, while they don't provide the greatest resolution in the world, all the circuits that go into them happen to be very interesting. R-E the direction of the extended thumb of the right hand with the fingers wrapped in the general di- rection taken around the loop. In the case of the static E field /Edl = 0, therefore v x e = o. The curl is a vector measure of the apparent rotation of the field about a point. If a number of E field instruments were scattered around a region, the group would not rotate. The divergence and curl of the types of fields we're discussing completely characterize the field; E can be found if V-E and V x E are known. This is known as Helmholtz's theorem. The curl of a vector field is al- ways zero, if, and only if the field is the gradient of some scaler field. Consider our h field exam- ple. If V x Vh were non-zero, then in following a closed path from some point and back to the be- ginning, one encounters dif- ferent rates of change of height times distance when taking dif- ferent paths. fVrrdl would be path dependent. That would amount to leaving from a point at, for instance, 50 meters in elevation and returning only to find the elevation is 300 meters, or 2 meters, depending upon what path was taken! The divergence of a field is al- ways zero only if the field is the curl of another field. Imagine the fields of Fig. 4 in 3-dimen- sional space. Curl the right- hand fingers in the direction of the apparent rotation around the point. The extended thumb is the direction of the curl vec- tor at that point. Conversely, consider the vectors shown as curl vectors. Direct the thumb along them and the fingers will curl in the direction of the field vectors. The field vectors seem to cancel, and not spread out. Those fields are the curl of an- other vector field. Try that with Figs. 2 or 4 and you'll get con- flicting results. Next time, we'll develop Ohm's law and look at the E field in materials, which will provide further insight into Maxwell's equations. r-e 79 AUDIO UPDATE The past, present, and future of tape cartridges. LARRY KLEIN ew audio/video formats are a big part of what makes life interesting for an audio jour- nalist. I've witnessed more than a few such introductions in the 30-odd years that I've been in the business. Some "revolutionary" new product designs immediately sank without a trace, others floundered for months or years struggling to keep afloat in the marketplace, and some — such as the LP. the cassette, the VHS VCR, and the CD — went on to make it big. What makes for new-format suc- cess? It's clear that the backing of a "big name" manufacturer is nor suffi- cient. As evidence, I cite the bal- lyhooed — but very short-lived — RCA, 3M, and Columbia home tape cartridges, the Fidelipac car stereo cartridge, and so forth. I'm sure that other ephemeral audio and video for- mats come to mind for those readers who made the mistake of investing in them. The Japanese are certainly not im- mune to cartridge-marketing mis- calculations. The Elcaset cartridge, introduced in 1976, was backed by Sony JVC, Technics, Teac, et a/,, and was intended to supplant both the open-reel and Philips cassette for- mats. As explained to me at the time by its project engineer, it was meant to appeal to those dedicated tape buffs for whom open reel was too inconvenient and cassettes were too low in fidelity. Although the Elcaset system worked well, its projected au- dience didn't exist in sufficient num- bers to get the product off the ground. Unfortunately several ware- houses worth of Elcaset players were ultimately scrapped. Obviously, I'm not trying to imply that the tape-cartridge/cassette for- mat, per se, is inherently unsalable. The Compact Cassette — to give it its g official Philips designation — got off to jj a slow start in the mid-sixties but ulti- § mately, as we know, became a huge £ success both for home recording and iii in its prerecorded form. My suspicion ^ that the positive response to the cas- 5 sette format had no necessary rela- £ tionship to its fidelity — or lack of it — was confirmed in the early 1980s. It was at that point that the annual sales of prerecorded music cassettes out- stripped those of the less expensive and better sounding LP's. If the fidelity of a format is nor the key issue for most music buyers, what are consumers looking for? Convenience, durability, and reason- ably low cost both for the machine and for blank and prerecorded tapes that feed them all are desirable at- tributes. And, of course, there has to be a wide range of popular artists available on the format. (The recent rapid replacement of the LP by the CD doesn't contradict my analysis. Sure, the CD sounds better than the LP, but the CD also is far more conve- nient to play, takes up much less space, and is much more durable. Furthermore, you can buy an excel- lent CD player at a fraction of the cost of an equivalent sounding, high-quali- ty record player and phono cartridge.) DAT disappointment When the home digital-audio-tape (DAT) machine was first introduced, my initial reaction was that it was an effective and sophisticated response to an essentially minuscule demand. There's no question that there has never been anything quite as good as DAT for the serious home recordist, for rock bands making live demo tapes, and for nature or sociological recordings. DATs wide audio band- width and excellent noise, distortion, and wow and flutter levels match or exceed those of the finest studio equipment. But is there a DAT advantage for the non-professional or the average music listener not obsessed by the need to be the first on his block to own a new product? If you were to compare a DAT recording to one made on a quality cassette deck, you would find DATs real-world sonic ad- vantage to be slight. And for playback in a car system, it would probably be nonexistent. That leaves longer play- ing time and ease of locating selec- tions as DATs only consumer advantage. Among DATs disadvan- tages are the high cost of both the machine and the blank tapes, and the dearth of prerecorded tapes — possi- bly because of difficulties achieving high-speed duplication. The Music Publishers Association (MPA) is still fighting for surcharges continued on page 83 THE NEW PHILIPS DIGITAL CASSETTES will deliver CD-quality sound in a player that is compatible with standard cassettes. 80 ;i;JI^;l»|i|?l?H»Wlil?l- The friendly Amiga. JEFF HDLTZMAN War — or at least an intense skirmish — broke out over my response to a letter from an Amiga-phile in the April issue. A reader chided us for not publishing more Amiga-related material; I re- sponded rather harshly. Since then numerous readers took the time to write and try to enlighten me. Several people simply rehashed Amiga tech- nical specs, but others raised some excellent points, especially regarding my admitted preference for IBM and compatible PC's. Ironically enough, in all the hubbub, we've still received no new articles on the Amiga, although a few are in the works. Before I discuss the reader re- sponses, let me explain why I have the attitude I do. Then when you dis- agree at least you'll understand where I'm coming from. How I became a PC-philiac In the fall of 1979 I bought a com- puter called the SYM. It had a 6502 CPU and 1K of static RAM, expanda- ble to 4K on- board. The SYM was 99% compatible with a previous 6502-based computer, the KIM. but better in that it had more on-board memory and I/O, better expan- dability, a faster tape interface, and the ability to display ASCII text on an oscilloscope. (Video terminals were so expensive in those days that peo- ple would use any CRT!) The SYM had a machine language monitor, but no assembler or BASIC. The company promised a ROM- based assembler and BASIC "real soon now CRSN)," but suffice it to say that it took a long time to get those items, during which time I learned much about the joys of pro- gramming in machine language by hand A user's group sprung up; by then I had written a machine-language de- bugger (which I sold through the user's group), a primitive RS-232 communication program (for transfer- ring files with a friend who used a SWTPC 6800), and had "modified" (disassembled and patched) a com- mercial text editor to work the way I wanted. (At work I used CP/M ma- chines, still too expensive for "per- sonal" use.) I also built my own EPROM burner and continually fid- dled with enhancing my software, burning it into 2716s, and installing them on the board. Eventually I bought a card cage and a memory board, and expanded to the limit of 32K. I almost bought disk drives at several points, but just couldn't justify spending $2000 for a pair of 80K drives (albeit with power supply). I learned a lot from those experi- ences, I used to know most 6502 op- codes in hexadecimal, and could view an uncommented assembly listing and get a pretty good idea of what was going on. I knew every address used for I/O in the machine. I knew every product on the market, as well as the expected release dates of all of those that were still in the RSN category. Eventually I got married and went to graduate school: at that point I couldn't afford to maintain the SYM as a full-time avocation. I needed something that worked, that I could count on, and that was supported in such a way that I knew I would be able to get the tools I needed. If you want- ed to pin down a precise moment when I adopted my current attitude, that was it. I looked long and hard at Apple ll's and Commodore PET's, for which lots of interesting software was avail- able, but found that their video dis- plays were poor, and expansion prices too high. Then Morrow Designs introduced a cheap (under $2000) 4-MHz Z80 system that included two 1 60K floppy drives. 64K of RAM, a 19,200 baud video terminal, and came bundled with some basic software, including WordStar and M BASIC. Of course, CP/M had its own assembler and de- bugger. The Morrow system got me through graduate school, and also helped me launch my career as a writ- er and journalist. I was working for a company in lower Manhattan that suddenly moved out to the middle of Long Is- land. Rather than change jobs, I bought a Radio Shack Model 100, and tapped out numerous stories while commuting on the Long Island WINDOWS AND DOS APPLICATIONS WINDOWS API SERVICES OS." APPLICATIONS P0SIX APPLICATIONS POSIX API SERVICES ^^ WINDOWS PROTECTED SUBSYSTEM jS OS/2 PROTECTED SUBSYSTEM | \ POSIX PROTECTED SUBSYSTEM V V EXECUTIVE [PROVIDES BASIC OPERATING SYSTEM SERVICES) | KERNEL~j £ A- r ^T HARDWARE:386-BA5ED. 4B6-BASED OR MIPS MACHINE > C CO c CO FIG. 1— MICROSOFT'S UPCOMING OS/2 3.0 provides an operating system kernel that can -i run Windows, OS/2, and POSIX applications in their native modes on Intel and MIPS 5. processors. _? 81 w o z O a: F o LU —I LU Q □ < EC Railroad. In fact, one of the first sto- ries I ever sold (to the now-defunct 80 Micro) was a hardware/software in- terface to allow the M100 to be used as a modem for a desktop machine — the Morrow. I used the Morrow until early 1986, when I decided that I just couldn't afford to let the PC world go by any longer. So I bought an XT, some IBM Technical Reference Manuals, and started learning everything I could about the machine. It was all down hill from there. I have no religious attachment to the IBM/compatible world. However, I do have a substantial investment in time and brain cells in it. I try to keep an eye on other markets, but it's im- possible even to keep up with all fac- ets of the PC market. Perhaps that type of personal his- tory has no place in a column like this. But I felt it important to show that I didn't just jump on the PC band- wagon arbitrarily. I've paid some dues, and I've always made my tech- nology decisions with care. On the other hand, as several read- ers pointed out, I as an editor of Ra- dio-Electronics have a respon- sibility to my readers. And I take that responsibility seriously. Over the years we've published stories on vir- tually all major personal computers, including Amiga's, Atari's, Macin- toshes, Apple ll's, etc. And don't for- get the 13-part series on the PT-68K we ran in 1986-87. Nonetheless, surveys repeatedly confirm that 80% or more of our read- ers own and use PC compatibles. And I suspect that 80% or more of our authors do as well. Unlike most other magazines, Radio-Elec- tronics relies heavily on its read- ership for editorial input. The lack of Amiga stories is traceable to that fact. Reader replies Anyway, here's what some readers had to say about the April column. Jim Belcher of Greenville. TX brought up an extremely important point: Standardization can stifle inno- vation. I agree — but there must be a balance, and it must be a dynamic, ever-shifting balance. Too much stan- dardization leads to innovation, which in turn leads to efforts at standardiza- tion, and so on. My interest in stan- dardization relates to interoperability, data exchange, and volume produc- tion. I'd like to be able to trans- parently connect numerous hetero- geneous computer systems to a network, and to share data among them. I'd like to be able to trade flop- py disks with Mac and Amiga users. I'd like to be able to plug-n-piay SCSI devices among them as well. I'd like video standards that would allow vol- ume manufacturing techniques to produce high-resolution video dis- plays as cheaply as TV sets. And so on. Innovation is absolutely neces- sary — but it must be carried out with- in the context of solving real problems. Paul Schick of Madison , Wl wrote a really thoughtful letter touching on standards and standardization, and points out that the issue is not "doomed PC's versus doomed Macs versus doomed Amigas, The issue is our own data, which we must some- how get out of that DOS window and onto that machine of the future, to say nothing of moving it from one application to another." Mr. Schick then goes on to lament how we have allowed manufacturers to bamboozle us into accepting proprietary data for- mats as a method of market control. Hear, hear! Tom Hutchison of Pilot Rock, OR suspects that the whole thing was an April Fools joke. Sorry. Neil Gjere of St. Paul, MN sug- gested that we do a price/perfor- mance comparison of various archi- tectures (Mac. Amiga, PC). When Apple first introduced the Mac II line, we approached the company for a review machine to do just that. The company unceremoniously declined. Attempts around the same time to contact Commodore went totally un- answered. IBM on the other hand has always been extremely cooperative, as have hundreds of other PC hard- ware and software vendors. We don't have the resources of Byte, PC Mag- azine, or Amiga World. But we don't try to compete with those magazines either. Patrick Greene wrote from Fort Ord, CA and objected to my state- ment that Windows has done more to promote graphical environments than all the Amigas and Macs put to- gether, and goes on to point out how the Amiga provides a better multi- tasking operating system. I did not say that Windows is better, but that it has been more successful in marketing the GUI, It wasn't long ago when the vast majority of PC users considered mice wimpy. The cultural shift brought on by the acceptance of Windows is amazing. Brian Redman of Richmond, BO (Canada) states that the success of the PC was due to two things, "its birth under the IBM logo, and the company's now recanted policy of open architecture." Good points. But then he goes on to say that, "The fact that IBM and Apple are just now wak- ing up to the usefulness of multi-task- ing, multimedia, etc., is a testament to the vision of the original Amiga development team, Xerox Star not- withstanding." Now there's an origi- nal way of distorting history. Multi- tasking predates both Commodore and the Xerox effort in the mainframe operating systems that were being used in the 60s. Frank Podroskey, Jr. of Mono- ngahela, PA berates my snobbish at- titude toward Amigas, saying that it "is what most Amiga owners resent more than anything else from owners of other machines." To that I plead guilty, and promise to try to be more open minded. Your turn So what are we going to do, read- ers? I say we because admittedly I can't do it all myself. You want more Amiga coverage? OK. Do it. The ball's in your court. It's time to stop saying "somebody oughta do some- thing" and start doing if. Don't re- write the technical specs, but do something creative — that's what all that multi-tasking and multi-media are about. Then tell us. We'll get the word out. Regarding news coverage, we'll try to keep a closer eye on the Amiga market. But if you see something you think should be publicized, let us know about it. Give us a company name, product/technology descrip- tion, and a phone number. We'll take it from there. News bits 486SX Released. Intel finally unveiled the 486SX, a 20-MHz coprocessor-less 486. Adding a coprocessor involves adding a new IC, which in effect is a full 486 that completely takes over for the 486SX. That's required because the CPU and the FPU must reside in the same package, else propagation delays negate any performance advantage. However, together the two cost 82 about 30% more than a real 486. Ini- tial benchmarks indicate that the 20- MHz 486SX runs roughly equivalent to AMD's 40-MHz 386. IBM, Acer, ALR, AST, Everex, and others imme- diately announced systems based on the 486SX, some priced well under $3000. IBM also showed a prototype 50-MHz 486 system, but there is no word from Intel on when production quantities will be available. One re- port mentioned a 486 that runs inter- nally at 50 MHz but has a 25-MHz bus interface: the chip could be a drop-in replacement requiring no system re- design or FCC certification. Clearly, with competition heating up in the 386 market, Intel is trying to establish a range of 486's at popular price points. Meanwhile AMD has an- nounced a 25-MHz 386SX but we don't know how much it will cost. Notebook Nirvana. HP and Lotus introduced a 10-oz hand-held 512K 8088-based PC compatible with 1-2-3 version 2.2 and several small application programs built in. It's amazing how much they packed in. but the display is only 40 charac- ters by 16 lines, and the keys are too close together for touch typing. Fu- jitsu has released Cin Japan only) a two-pound notebook that is an inch thick, has a full keyboard, runs for 8 hours on two AA batteries, and has no rotating parts (i.e., disk drives). It's based on Intel's 386SL and uses IC cards for volatile and non-volatile storage. And Kyocera has released Calso in Japan only) a pen-input DOS- based system built into a thin binder. The inside cover contains a 240 x 340 pixel screen used for both input and output. A separate tablet clips into the binder, communicates with the screen via inductance, and provides some sort of keyboard. There's talk of marketing the device in Europe, and possibly also here in the U.S., although no firm date has yet been determined. IBM and Microsoft continue to di- verge on Windows and OS/2. IBM has teamed up with Micrografx, a premier developer of Windows- based drawing tools, device drivers, and Windows-to-OS/2 porting tech- nology, to co-develop a 32-bit graph- ics engine to replace the current 16- bit engine for the OS/2 Presentation Manager. There's also talk that, like Windows. OS/2 2.0 will include a suite of basic desktop applications. In addition, IBM has shown OS/2 2.0 running DOS and Windows apps si- multaneously and faster than in their native modes. On the Windows front, Microsoft talks more and more about OS/2 ver- sion 3.0, AKA "New Technology," a portable version that will have the ability to run Windows. OS/2, and POSIX applications simultaneously over the same operating system ker- nel. Microsoft is still struggling with TrueType, its PostScript killer, and in the meantime, Adobe's ATM is get- ting lots of good exposure. In addi- tion, Adobe is about to introduce an enhanced version of its font tech- nology that will allow a continuous range of letter weights from very light to very bold. The FTC is investigating charges that Microsoft hasn't been on the up and up regarding separat- ing its systems and application divi- sions. Look for the company to split by year end. R-E AUDIO UPDATE continued from page 80 on blank DAT tapes to compensate them for the assumed losses result- ing from unauthorized dubbing of their copyrighted material. Their argu- ment is that since DAT copies of CD recordings are virtually perfect, con- sumers will be encouraged to engage in orgies of unauthorized dubbing. The fact that you can already make a virtually perfect copy of a CD with any high-quality cassette deck seems to have escaped the MPA's attention. And the additional fact that all DAT decks come with circuits that prevent multiple copies of the same CD seems to have deterred the litigating music merchants hardly at all in their pursuit of enhanced royalties. In my May 1988 column, I predicted that the DAT format — for ail the rea- sons discussed above — wouldn't make it as a mass- market product. CI was probably the only U.S. audio writ- er who wasn't all moist- and starry- eyed about DATs prospects during those early days.) The present word in the hi-fi industry is that DAT sales are poor and that as a consumer product it is dead or dying. Any child- ish pleasure that I may derive from "I told you so's" is offset by considera- tion of the enormous amounts of time, effort, and cash invested in de- veloping the DAT technology 1 hope it won't be a total waste, and that there will be some worthwhile spin-offs in the future. DCC? Are you waiting with bated breath for my pronouncements on the Dig- ital Compact Cassette? Or have you even heard of it? Philips promises that by mid- 1992, new format ma- chines will be available that will play both standard cassettes and similar size digital cassettes employing a new "precision adaptive sub-band encoding" data-compression sys- tem. PASC encoding, perhaps need- less to say, is incompatible with any current coding system. Philips promises that the DCC tapes will sound as good as CD's and will have the advantage Cover conven- tional cassettes) of CD-type program selection. Projected playing time is 90 minutes, but that will probably be extended. Tandy has already demon- strated prototypes, and there's a rumor that the giant Matsushita Cor- poration (Panasonic, Technics, JVC) is ready to commit to the format. Price of the machine is projected at between $500 and $600— about the same price as a high-quality cassette deck. Will DCC be a hit or a miss? Short of unlikely fidelity problems in the PASC encoding, and endless litiga- tion by the music merchants, I don't see how the format can fail commer- cially It incorporates the known and well -accepted virtues of conventional cassettes and promises CD-level performance and convenience for its digital cassettes. There are design er- rors waiting to be made in the new machines — such as providing less than state-of-the-art performance from the conventional part of the ma- chine — but if these are avoided, then DCC will be the wave of the future. I'm sure that Sony will go down fight- > ing for DAT — as they did for Beta — ® but I'm afraid it's a lost cause. As I've « said before in this column: In a year or -^ two, we'll know if I'm right. R-E <% 83 MARKET CENTER FOR SALE TUBES: "oldest," "latest." Parts and schematics. SASE for lists. STEINMETZ, 7519 Maplewood Ave., RE, Hammond, IN 46324. ■ ENGINEERI NG so ft ware , PC MS DO S/Ci re u 1 1 design and drawing, PCB layout, Logic sim- ulation. FFT analysis, Mathematics, Circuit analysis. Call or write for free catalog. 1 (800) 728-3805, BSOFT SOFTWARE, INC., 444 Colton Rd., Columbus, OH 43207. R ESTR1CTE D technical information : E lectronic s u r- veidance, schematics, locksmilhing, covert sci- ences, hacking, etc. Huge selection. Free brochures. MENTOR-Z, Drawer 1549, Asbury Park, NJ 07712. CABLE TV converters: Jerrold. Oak, Scientific At- lantic, Zenith & many others, "New MTS" stereo add-on: mute & volume. Ideal lor 400 and 450 owners! 1 (800) 826-7623, Am ex, Visa. M/C accept- ed. B & B INC., 4030 Beau-D-Rue Drive, Eagan, MH 55122. TUBES, new, up to 90% off, SASE, KIRBY, 298 West Carmel Drive, Carmel, IN 46032. C AB LE d esc ramb lers {Jerrold) from $40 . 00 . Toco m VIP test chip. Fully activates unit. Also Zenith test board. Fully activates Z-Tacs. S50.00. Call (213) 867-0081. PREVENT descrambler detection! Order Tech- Block today! Simple in-line connection. Only $19,95 P.P.D. THE STAGE DOOR VIDEO, PO Box 518, Belleview, FL 32620. For CO. D.'st (800) 395-4557. o o rr t- o UJ Q < rr CALL DOCTOR DESCRAMBLER ...for symptoms relating to scrambled cable T.V. signals. We have • JEREOLD • TOCOM • ZENITH •HAMLTU'OAK • SCIENTIFIC ATLANTA. Six month warranty! We ship C.O.D. Lowest retail/ wholesale prices CATALOG: VISA, AM.EX. Global Cable Network 1032 Irving St. Suite 109 S.F., CA 94122 NO CALIFORNIA SALES1I1 OPEN SATURDAYS FREE M.C., 1-800-327-8544 CHIPS burned. EPROMS, EEPROMS, PALS, GALS, bi-polar PROMS, 8748 S 8751 series de- vices. Dial our BBS at (606) 253-4962 for details. SHAREWARE, 1000s of programs available. 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Copy to be in our hands on the 5lh or the third monih preceding the date or the issue, (i.e., Aug. issue copy must be received by May 5th). When normal closing date falls on Saturday, Sunday or Holiday, issue closes on preceding working day. Send for the classified brochure. Circle Number 49 on the Free Information Card. 84 FREE CATALOG FAMOUS "FIRESTIK" BRAND CB ANTENNAS AND ACCESSORIES. QUALITY PRODUCTS FOR THE SERIOUS CB'er. SINCE 1962 FIRESTIK ANTENNA COMPANY 2614 EAST ADAMS PHOENIX, ARIZONA 85034 LASER beam in, animation out of spinning holo- gram! From stellar to sexy. Brochure. HOLOVI- SIQN, (206) 6S2-7559. ___ CABLE TV converters and descramblers. We sell only the best. Low prices. SB-3 $79.00. We ship C.O.D. Free catalog. ACE PRODUCTS, P0 Box 582, Dept. E, Saco, ME 04072. 1 (800) 234-0726. T.V. notch filters, phone recording equipment, bro- chure $1.00. MICRO THinc, Box S3.''6025, Mar- gate, FL 33063. (305) 752-9202 PHOTOFACT folders under #1400 S5.00 Others $7.00. Postpaid, LOEB, 414 Chestnut Lane, East Meadow, NY 11554. (516) 481-4380. CABLE CONVERTERS all major brands info * orders 1 (800) 782-0552 FREEWAY INC. (s.rti.p.), PO 5036, Burnsville. MN 55337. CIRCUIT Center — Complete circuit fabrication from single piece single sided to production multi- layer. Also — Laminate $5.50,'sq. ft., etch $3.50/qt. Thru hole plating available too. CIRCUIT CENTER, Dept. 001, PO Box 128, Addison, IL 60101. (708) 543-0671. WIRELESS CABLE RECEIVERS 1.9 TO 2.7 GHz Q 30 W PARABOLIC DISH SYSTFM S173.90 3D CH H0O WITErlNA SYSTEM 1193.90 30 CH CRYSTAL CONrROUED SYSTEM Si94.9$ SUN MICROWAVE INT'l.. INC. SEND S1 00 TOR P;0 RO MHZ UTALOG OH THESE FW) Effl K. M . I S067 AKD0THERFIHE 1 60?! 230 1Z« VI0E0 PRODUCTS CUtNTITY DISCOUNTS aaaERS OUT :.SKHJ4«» (IDE mi SUPER low prices on computers, motherboards, hard and floppy drives, add-on cards. We have ev- erything. Full line of test equipment at unbeatable prices. Call for free catalog. APPLIED ELEC- TRONIC RESEARCH, INC., 4701 SW45th Street, Ft. Lauderdale, FL 33314. (305) 987-9785. FREE catalog. Interfaces for IBM compatibles. Dig- ital I/O 48 TTL lines (2ea. 8255s) $69.95, 16 ch. analog input to 5v 8 bit. $89.95. JOHN BELL, 1381 Saratoga St., Minden, NV 89423. (702) 267-2704. CB RADIO OWNERS! We specialize in a wide variety of technical information, parts and services for CB radios. 10-Meter and FM conversion kits, repair books, plans, high-performance accessories. Thousands of satisfied customers since 1976! Catalog $2. CBC INTERNATIONAL P.O. BOX 31500RE, PHOENIX, AZ 85016 HOTTEST cable bargain, all descramblers come with a factory refurbished 61 channel remote con- verter at the price you would pay for a descrambler only. SA-3-B with converter $89.00, fast Tri-Bi with converter $89.00, MLD-1200 Hamlin with converter $79.00. S.A.C., 1 (800) 622-3799. PC scope. 24 Mhz digital scope board for the IBM PC & compatibles. 2k ram, PRE & POST trigger, ,5V to 50V range, software with FFT. Uses PC short slot, S175.00. Call or write for free demo disk. SOFTECH, 51 Willow Ct. Hamilton, NJ 08619. (609) 588-0679. INTERFERENCE tillers, all channels Best quality, cylinder type. Best prices. Visa, MC, COD accept- ed. Large quantities available. We now have ch# 10 and 11 in stock. 1 (800) B72-5912. EXOTIC miniature electronic devices, catalog $5.00, refundable. F&P ENTERPRISES, Box 51272. Palo Alto. CA 94303-L. CABLE TV converters & descramblers for Jerrolri and Scientific Atlanta. Low prices, one year warranty. We ship COD. BAY STATE ELECTRONICS, P0 Box 103, Boston, MA 02188. 1 (800) 359-9806. CABLE bargains, RTC-56 $99.00, Tocom 5503A $199.00, M-35-B Oak $35.00, Hamlin CRX-6600-3M $125, Hamlin MLD-1200 $49.00, X-12 Oak $49.00, 4040-DIC S89.00, all others in Stock. S.A.C., 1 (800) 622-3799. CABLE descramblers, new X-12 Oak descrambler $49.00 — 1, $39.00 — 10, 529.00 — 20, Hamlin CRX-66O0 with remote $129.00—1, $110.00 — 10. $99.00 — 20, Oak M-35-B $40,00 — 1, $35.00 — 10, $30.00 — 20, 5503A Tocom with remote $199.00, Sylvania-Texcan 4040-DIC with remote, replaces Jerrold 400-DIC S99.00 — 1 , $89.00 — 10, $69.00— 20, Oak RTC-56 with remote $125.00— 1, $115.00 — 10, $99.00 — 20, SA — Tri-Bi — Zenith — same low prices. MOUNT HOOD ELEC- TRONICS, (503) 253-0459. Quality Microwave TV Antennas WIRELESS CABLE - IFTS - MMDS - AmaT.ur TV Will High Gain 50* |+] • Tumitsto 1.9 to 2.7 Gtu. • 36- Oi aims' System Complete SI 49.96 • 1 2-Crisnnel Syslem Complete S 114.95 . Call or write [5ASE1 tor "FflEE" Crams PHILLIPS-TECH ELECTRONICS P.O. Boi 8533 ■ Scottsdate, AZ 85252 : (602) 947-7700 iss.orj Credit All phone erderil WARHANTY MasterCard • VI si ■ CD D ' E • Quintity Pric Ing VCR secrets. Booklet shows how to record 8 hours continuous audio on VCR. Nothing to build. Send $10.00 to: BROOKSIDE INNOVATIONS, Box 62, Martinsville, NJ 0BB36. COMPLETE IBM computer system, new, 640K memory with keyboard, monitor, two drives, $495.00. Includes one year warranty. Send $5.00 for information to THE DATA FACTORY, 7433 Kai- ser, Fontana, CA 92336. THIS, SPACE CONTRHW ED*5 * *LnXt St ftwCE A defense against cancer can be coolted up in your kitchen. "There is evidence thai dter. and cancer are related. Follow these rnodincjiions in your daily diet to reduce v v.j.i ices of getting canter: 1. Eat mure high-fiber foods such as fruits and vegetables and whole-grain cereals. 2. In dude dark green and deep ydJow fruits and vegeta- bles rich in vitamins A and C . 3. trvcludc cabbage, broccoli, brusscls sprouts, kohlrabi and cauliflower. 4« Re moderate in consump- tion of salt-cured, smoked, and nttrke-curcd foods. 5 - Cut down on total fat in- take from animal sources and fats and oils. 6. Avoid obesity 7. Be moderate in consump- tion of alcoholic beverages . No one faces can cer atonc ^AMERtCAM CAHCEfl SOCJETf SAlLQm CHOOSE FROM THE FOLLOWING PACKAGES: PKG.*1... ■J ft PANASONIC 1453G CONVERTERS $65" PKG. '2... 8 SCIENTIFIC ATLANTA 85364- COMBINATIONS $175 I IvUa «■)■■■ 5 SCIENTIFIC ATLANTA 8580 COMBINATIONS $215 PKG. "4... 4 ft MIX AND MATCH ADD-ONS «45 ! ALL EQUIPMENT IS BRAND NEW. FACTORY FRESH !!! (800)234-1006 MttUKADY tar aiikj'J rtomroruyt. jtij a catsoj v"^ t f PERFECT CABLE CONNECTION !! Perfect Cable Connection & totally committed to customer satisfaction. Our primary concern is lo provide you with (he nighest quality converters and descramblers at the lowest cost We employ lull lime technicians to insure hassle iree service and iroubleshoot any situation Call us today and let us prove lo you why we are the Perfect Cable Connection. ■ E months 100% parts & labor • 24 months warranty available ■ Full technical support ■ On-line computer system ■ 30 days money back guarantee ■ Most orders shipped within 24 hours ■ Visa. M C, AMEX - 5% ■ Dealers welcome • COD Jerrald SA 8S36 ft n F-.rji;,U fiC 83 W Ft N*w' 1 i- ', 4CO OflX 3 DtC W R 1 69 ■ 99 Ch capacity ■ i 1 119 to 69 ■ WlffllfttS remote »■. 5 89 ,,, 20 65 ■ AutpmiSlC 'n':a l..iiir:j to n KJ , -Q SO 60 ■ Parental lock ?0 69 50 65 w rjui 100 55 ■ Med* m Japan ' S«MfHTlllt ■ J*' IQO CALL | ■ F a^njo ffwiwy dwnti l.'-n:-:-. ' 450 DF1Z 3 DC W R 1 129 iW Zsnrlh ZTACS 5 99 IM All motfelj ' , 20 75 Call for prices . 64 50 CALL W . ... 100 CALL i all Jerrold 400 SA-ae FTB-3 ORX3105 Wfl 1 75 IMS Dltf-.l Wfl l 99 1 55 ID 48 H to 79 5 49 20 43 20 65 10 45 ■O i ■ 50 39 so CALL SO 40 100 35 irjo CALL WE WILL MEET OR BEAT ANY ADVERTISED PRICE IN THIS MAGAZINE. PERFECT CABLE CONNECTION 702-358-2763 2209 Oddie Blvd., Suite 321 Spark, NV 89431 > c © c 85 Cable Descramblers New Auto Tri-Bi guaranteed no Flashing $165.00 ZENITH SUPER SAAV! S199.0O TOCOM , $319.00 EAGLE..._ S119.00 COPY GUARD S59.9S STARGATE 2000... SS8.O0 SB-3 J99.00 TRIMODE. $109.00 HAMLIN. $99.00 SCEENTEFIC- ATLANTA Jl 19.00 OAKM3SB.... $99.00 zenith siTs.oo M.D. Electronics will match or beat any advertised wholesale or retail price. Your best buys and vt arranties f BT5S0.72ndSt lX„ JSF Ommtw, NE 6ST14 SY CXrmMK CftlLE TV lOOPMShlT FHOM M.D. ¥LBCTKDFaCS THE FLTBCe EASEE AGREES TO CCWPLY WITH ALLSTATE AND FKCGEALLAWS RECAKDTJVC; JTUVATE OWNtBECPCf CAILETV KfBBBtt, f YOU AM UN5LTSE OF Tl IE$E LAWS CHfiCK WITH TOUR LOCAL OFFICIALS. CIRCLE S3 ON FREE INFORMATION CARD CABLE T.V. DESCRAMBLERS w o z O rr F o LJJ I UJ I O Q < rr 86 BASE BAND $399.00 Starcom 7 DQN7V $120.00 SAS5S0 $299.00 TRIMODE $95.00 SB3 $74.95 ZENITH 1612. . . $329.95 PIONEER $399.00 DQN7 $99.00 MANY MORE.. .CALL OR WRITE FOR FREE FAST INFORMATION. YOUR BEST BUY'S & WARRANTIES FOR CABLE CONVERTERS AND DESCRAMBLERS START WITH A FREE CATALOG FROM: WORLDWIDE CABLE 7491 C-5 N. Federal Hwy. Suite *142 Boca Raton, FL 33487 ORDERS AND CATALOGS CALL TOLL FREE 1-800-772-3233 [ttoltuCetd C.O.D. BY ORDERING CABLE TV EQUIPMENT FROM WORLDWIDE CABLE THE PUR CHASES AGREES TO COMPLY WITH ALL STATE AND FEDERAL LAWS REGARDING PRIVATE OWES SHIP OF CABLE TV EQUIPMENT. IF YOU 4RE ] UNSURE OF i 'l££ LAWS CHECK " 1TH YOUR I CALC F1CWIS. PLANS AND KITS DAZER personal protectors! Lasers! AM/FM/ln- frared transmitters! Detectors! More! Kits/as- sembled. Catalog $2.00. QUANTUM RESEARCH, 16645-113 Avenue, Edmonton, Alberta T5M 2X2. SURVEILLANCE — Audio ; video/infra-red.')aser equipment. Industrial or private. 500 item catalog $7.00, SECURITY SYSTEMS, 3017G Hudson PL, New Orleans, LA 70131. DESCRAMBLING, new secret manual. Build your own descramblers for cable and subscription TV. Instructions, schematics for SSAVI, gated sync, sinewave, {HBO, Cinemax, Showtime, UHF, adult) $12.95, $2.00 postage. CABLETRONICS, Box 30502R, Belhesda, MD 20824. -LASERS^ New Laser Diodes s 15 Helium- Neon Laser Tubes from s 25 4H . :«■ COMPLETE HELIUM -MEOW LAS EH S FROM $59°° FREE CATALOG Call or Write Today I M E RE D IT K IN ST HUME NTS PC Bffi rwiGKrdilt. U 8S311 TO 53J-93S! SMD How to use surface mount technology. Build ultra miniature projects. Plans included free, infra red control, and an interesting light display. Send $15.00 to CHARLIE'S VIDEO, Dept. SRT. PO Box 7732, La Sierra, CA 92503. H QB B Y/broadcasting/H AM/C B/s u rveillance trans- mitters, amplifiers, cable TV, science, bugs, other great projects! Catalog $1.00. PANAXIS, Box 130- F8, Paradise, CA 95967. BUILD from simple materials, phenomenal econo- my carburetor. Detailed plans for five versions. Good science project. Send S2O.O0 cheque, money order or Visa to: VALLEY MICROWAVE, Station C, Bear River, Nova Scotia, Canada BOS 1 B0 or phone (902) 4< rT -3577. REMOTE CONTROL KEYCHAtN Complete whTdnWransmlltef':: end +i vdc HF receiver.': Fully Assembled including plans:: to build youf .own auto alarm: i: Quantity discounts available !:! Ana ftc ChecKVViss or MiC- 3>Z't,yp Add.SSstilppina;:: VISITECT INC. BOX 54«, SO.SAH FRAN, CA. 94080 (415)531-HB425 Fax (415) 531-8442 HYPNOTIZE or Relax electronically' Alpha'medila- tion goggles. Complete kit $53.00. Free information. MARK WORLEY, Box 261113, San Diego, CA 92196. SURVEILLANCE transmitter kits! Four models of each; telephone, room, combination telephone/ room transmitters tune from 65to 305 MHz. Catalog with Popular Communications and Popular Electronics book reviews of "Electronic Eaves- dropping Equipment Design," $2.00. SHEFFIELD ELECTRONICS, 7223 Stony Island Ave., Chicago, IL 60649-2806. FREE cable and satellite descrambler plans. Send self addressed stamped envelope. MJM INDUS- TRY, Box 531, Bronx, NY 10461-0208. ANNOUNCING: AN END TO HIGH MONTHLY CABLE FEES! All Jerrold, Oak, Hamlin, Zenith, Scientific At- lanta, Magnavox and all specialized cable equip- ment available for shipment within 24 hours. For fast service MC/VISA or C.O.D. telephone or- ders accepted. 60 Day Guarantee (Quantity Dis- counts). Send self-addressed Stamped enve- "^ 1-800-232-5017 HBH C.O.D. ORDERS \^^ I l^^» ACCEPTED UMM CABLETRONICS, INC. 1 3M E, A Igo n q u in Road Suite501 Algonquin, Illinois 60102 TBC frame synchronizer kits for 1/2 and 374 inch VCRs $595.00 to $1,895.00 ROGUE RESEARCH, (503) 582-4324, PO 729, Rogue River, OR 97537. INVESTIGATORS, experimenters — Quality new plans. Micro and restricted devices. Free catalog. Self addressed stamped envelope required. KEL- LEY SECURITY, INC. Suite 90, 2531 Sawtelle Blvd., Los Angeles, CA 90064. TELEPHONE caller identifiers. Displays incoming caller's telephone number, kit $49,95 postpaid, SURVEILLANCE catalog $5.00, EDE, FOB 337, Buffalo, NY 14226. DESCRAMBLER kits. Complete cable kit $44.95. Complete satellite kit $49.95. Add $5.00 shipping. Free brochuie. SUMMIT RE. Box 489, Bronx. NY 10465. No NY sales. MAXIMUM security for mini-price. Our versatile microcontroller lets you design the vehicle security system you want. Choose your options from those available in high-end systems, including: passive or active operation, zone status reporting, surveillance monitoring (informs of intrusions), chirp and sensor bypass, five monitored loops, three control outputs, panic alarm, valel mode, A/V display, full remote capabilities, etc. Kit includes micro-controller, sche- matic and instructions. To order, send $34.95 + $3.50 S/H to: KHEPRI TECHNOLOGIES, PO Box 460186, Aurora, CO 80046. Delivery in 2-4 weeks. Or call (303V 680-99A9 for detailed informational :'RCLc 19^ ON FREE INFORMATION CAHC ANTIQUE RADIO CLASSIFIED Free Sample! /^^^S^f^Sn Antique Radio's ^^^Tfflw^iJ Largest Circulation Monthly. | BB© M o 1 Articles, Ads & Classifieds Fj-Mont h Trl a I ■ $1 5 . 1 -Y r : S27 ($40-1 St C I ass) . A.R.C., P.O. Box 802-L9, Carlisle, MA 01741 CABLE TV Secrets — the outlaw publication the cable companies tried to ban. HBO, Movie Channel. Showtime, descr amblers, converters, etc. Sup- pliers list included. $9.95 CABLE FACTS, Box 711- R, Pataskala, OH 43062. BUILD subwoofers for home theater. Save. Com- plete instructions $6.95. WILLIAM CROWLEY, 2116 Wilson. Hollywood, FL 33020. PCB and schematic CAD. $195.00 IBM EGA CGA Multilayer, rubberband, aulovia, NC drill, laser, dot matrix, plotter, library, Gerber, AUTOSCENE, 10565 Bluebird St., Minneapolis. MN 55433. (612) 757-8584 tree demo disk. WIRE sorter, save time and money when Identifying multiple wire runs and bundles. Easy to follow prints and instructions. Send $5.00 to PATTEN ENTERPRISES, PO Box 1666, Spring Valley, CA 91978-1666. CA residents add 35 cents. CABLE DESCRAMBLERS OAK M35B COMBO 539.35 Jerrold, Zenith, Hamlin, Sci. Atlanta. Pioneer & MORE! OUR PRICES ARE BELOW WHOLESALE! CABLE+ PLUS 14417 Chase St. #481-A Panorama City. CA 91402 1-800-822-9955 • Other Info. 1-818-785-4500 NO CALIF. SALES - DEALERS WANTED I'LL HAVE MINE DESCRAMBLED If you find a better deal, We'll beat it! JBBROLD • TOCOM • HAMLLW • OAK * SCIENTIFIC ATLANTA • ZENITH • ask about our warranty program C.O.D. Visa, M/C, AM.EX. welcome. •FREE CATALOG • FHEE CALL •OPEN SATURDAYS I 800 562-6884 VIDEO TECH 3703 S. Virginia St. Ste. 160-304 Reno, NV 89502 SATELLITE TV FREE catalog — Lowest prices worldwide, save 40 — 60%. Systems, upgrades, parts, all major brands factory fresh and warrantied. SKVVISION, 2009 Collegeway, Fergus Falls, MN 56537. 1 (8O0) 334-6455. DO it yourself, systems, upgrades, major brands discounted, save 30% — 60%. Lowest prices anywhere. L.J.H. INC., call Larry at (609) 596-0656. THE ELECTRONIC GOLDMINE has ore tf fe paisa se-1 lacf ire ol unigje etecirarMl Mlabls in Gicwfltf IhvEIU - We have cro 130 1 DIFFERS J kits and awe i,wlma*S \ unique, barpain iffiffiH, pros}. ojrtBBerts IJSJuESTlOUFI ill HI CM w 1 coK TODMI rrr moose Prcr-.cn ncjsc nE* fcr me rTT IIJW ysrjrvi on-puif s-iircei tsrtvt wan caies. tor conairing crcui pc*i. mouse, softvrara tfaene aid irarifll. Ac 00 CS16 $5.< (NFRrWED DETCCTOtt KIT Goal For Kl/ig and wrtcaiHi of Wars! Qilpii U5H Kfisrjfl snsyr and efidrflruc drcu2ry to rBtfftf to HI tjflH or irfr^rt TV. VCR, ec njfrdc rarirolfcn and LEDs pmdifjrq tarti m lir/iling a tnr/U rsl LED, SW ttfsy [itf irduttd). Size li twnJ: IS t T.r, CcmpW£nflH all fB&, PC tcati and instrixrcrg CM41 55,95 ULTRASONIC PEST REFEOEH KJT - taDflfcng lo re- StStfl, taw irlEnstty ulirasorflc sound wms repel resets and small rodirtj. Tee cupif :' '■; kii 6 cftuioti ta me pes. but Q abefrt Iht-iraring ranjed titans, dOQS, Cafe, Vd EJirdS. boanc Z5" 1 2". CccrflWe itt ail cgrti. FC ton) and ns&ufim! C6350 $9.00 4KV TRIGGER COIL Us wlh any s;r;&! vbtB-a nfiKSl 3 lead 4KV tfgger. NI7O0 Si JS £X 100 for $80.00 IIWERTER TRANSFORMER Small 4 leid ifaftStflJiMf tor use wiih 555 € to ojfwrt twoc to aov iff tfroWtOrBOrt \JX wih schcratic. N1703 $2.00 EA 10 l;r Si 8.00 STROBE TUBE & SCHEMATIC^^ti Bright ananrf^^ Hash lute toff ( matonrj | { j/oCe Tift fcncWts xhe^c sltiwwg ily lute and iiigg-r coil show Si* Sis d lute 1.5* ULTRAVIOLET SENSOR SUN EXPOSURE METER hwxEJn i'-. Small ifccTon; dewa detects LP/ MWfl tail the sun and saxes a signal «ten yaj'vs had etoiqii Equsun. lias 2 dials lor iltin rype and am saan raling (SPF)l Ush C draiiiry and special UV sensv. Assemried and ready to ua, "lis new sjrplu) fe«-n is ficmr Mittbte il a haditfi 01 Ins micM cosJ (fteuees SV teneiy. net ocludetL) GSM $8.95 MINIMUM OBDEH: $10 DO plus $3 00 stippng aid fan we acem MO. visa and uomy Onten; SEND ORDERS TO: I)» EKanyK GoBrnna P O Bon 5403 Sconal*. AZ 85261 L PM01IE ORDEH5 (&02J -lS1-74n] FAX ORDERS 1GP2;, J51-94S5 CIRCLE 180 ON FREE INFORMATION CARD MARK V €L€CTRONICS, INC. Competitive Pricing * Fast Shipping Since 1985 A indicates the level of difficulty in the assembling of our Products. ORDER IN CALIFORNIA 800-521 -MARK ORDER OUTSIDE CA 800-423-FIVE FREE CATALOG & INFORMATION (213) 888-8988 FAX (213) 888-6868 Amplifier + Metal Cabinet + Transformer Kit Set Assmb. Set TA-3500 LG-1925 #007 $155.61 $179.36 TA-477 LG-1925 #003 $125.21 £141.3 6 TA-802 LG-1924 #001 $100.45 $113.54 TA-1000A LG-1924 #001 $113.52 $133.36 TA-1500 LG-1925 #001 ▲ Beginner 1A Intermediate AAA Advanced * - "I $1 30.00 $150.00 _i^^_JH H 1CI ^^ I! urji I Ira £5® TA-802 Fully Assembled TA-1000A ■ Due lo Itiis siwctal oiler & low price, we can only excharige or repair any ol lliese units ITA-3600. TA-477, TA-S02 £ TAiDOoft) wthln IS days ol your rec&lp! ■ The above pnees are lor Ihe complete srns. For separate unil pice, pleasa see below. TranstOrnter '^ AMPLIFIERS KIT 1.SSEMB. TA-477 Melal Cabinet H1SCELUHE0US KIT ASS EM B. MODEL TA-2IMK2 TA-50A(6 TA-50C rA-liOMK! TA-30D rA-3!3ft rA-377* TA-400 rA-477 rA-SuOMK! "A-sg; r«-lDO0A tA-1500 IA-!?(B TA-24Q0A ;;■;■::: TA-Z800 TA3000 TA-36M SM-!» SM-3?8 su-m SM-SSS SM-A68 OESCHIPTION Dkgilad V04C1 Memo AA Mulli-Puiposc Melody Ikfteraiorji MuiliP-j'pose Melody {Mjppy fliithday. Wedding March etc I 3oW C13SS "A° Main Power Mpno Amp. A A 30W Muhi-Purppse Single Cnannet Amp. A -^..^,— SOW • 60W Sleieo Power A-npli In: iwiih Mic InpullAA . 30W X 2 Sterep Pre-mam Amp. A . . $3000 1284 A 13.65 ....31 SO 30-00 Stale ot Ihe Ad Felly Complementary Symmetrical f ET Pre-Amp. . 40W Solid Slate Mono Amp. A , IJOWMMIetPowei Mono Amp. AA -—..—— 120W i 120W Low Tim Pre- Main Stereo Power Amp A. A _ WW . BOW Pure DC Stereo Main Power Amp AA . tOW Dtymmic Class 'A' Mam Power Mono Amp.AA 100W K ; Class 'A' OC Slereo Pre-Main *mp. AAA DC Fet Super Class '*• OC Pit-Amp AAA Electron* Echo £ Reverberation Amp + ~.. ~^.-_ KQ Pre-Amp wnOc-aoo graph* equaiiier * 01- FET IC Pre-Amp w/3 way tone cootrot AA „ _ _ _.... Slereo Simulator (For Mono TV pr Any Mom Sources A A ........ MOW HO Hi-fi Power Moirp Amp AAA 7 Sand HI-FI Sraphic EpiialiiH AAA 4 Chawiel Prolessional Color Light Controller* AudioVmeo Surrpurrd Soirml Processor AAA* Dynamic Haise Redirelron A ..„_, Llniversal AudioMdco itAFtAOKE Miner. Pre-Amp * . .. 67.00 -.3150 . 59.95 ..2800 59 00 639! .45 94 .59.69 73 70 47 70 48.90 27.00 85.00 26.40 65 00 1720 1871 42.80 29.00 78.00 42.80 75.00 3453 B5 00 5372 *60,S8 95 at 6624 96 00 68.80 6357 38.60 110.00 36.80 145.00 75 00 34.00 225 00 MODEL TT-23B TY-26 TY-35 TY-3- TY-3! IY-4tMd TY-42 T¥-4i TY.45 Ty-47 10.00O-. I CESCRIPTION 3 Channel Color Light Controller * Stereo Loudspeaker Proledpr A . rM Wireless Mcrophone A AODCOuirt! Digital Click a Sourid /Touch Control Switch i miivaf Fiemoie Cniuol Umi iw/Caset A a a 3ar/ Cot level Meier A A 31* Oigiiai Panel Meier A 20 Steps Bar / Do! Audio Level Drsplay A A . Superior ElectroAic floulene A A V Capacitor (Suspestco lor TA-3600. TA-477. TA-1000A 6 TA-802 1 .14 66 11 25 . 19.00 12.00 2200 24 15 29.00 38.45 19.46 S 65.00 20.85 ?i20 35.00 33.81 38.00 46.14 2724 2300 F1EGUUT0RS BT *SSEMB. TR.355A 1P-3558 TR-503 0-I5V 5A Regulated DC Power Supply I no case £ x loimer) A O-30V 3A Hegulaled DC Power Supplv I no case £ xTofmer) a '.-50V 3A Regulaled DC Power Supply mo case £ x'lormerl A A .615.GS 62176 1S.6S 21.76 16 75 23 65 METAL SABINE IS WITH ALUMINUM PANEL MODEL U3-1273 LG-16B4 U3-1924 LG-1925 LG-1983 H ■*■ t V MATCHING 3" 4' 4 5' 21 :? 16' I? \W irur 7- TA.260O, TA-37JA, TA-22O0 B - TA-323A. TA-377A. TA-2200 Ill* TA.802.TA.15O0.TA120MK2. TA-600 MW. TA-I00OA . Il» TM77. TA-800. MK2. tA-1500. TA-1000A. TA-3600 .. r TA-377A. TA-2800 TA-2200. TA-120WK 2 PRICE .622.65 ... 27 50 32.60 . 35 60 29 25 POWER TRAHSfORMERS DIGtTAL METER SAND COUNTER KIT ASSEMB. SM 43 SM-4B SM.48A SM-49 SM100 ; C-i-::ir..- 3 "r Mulu-runcKmal Led D P M tw/ABS plaslic case^AA 4IH Hr-Precision D.P M.AAA 4'£ Hi'Precisipn D.P M. (w'ASS piastre caselAAA ..- 3viMulti-FunclconalLCOD.M.P [wiHoldFunclionlAA . [50MC Digital Frequency Counter AAA 1 GHf Frequency Counter w ^_~_ 5 34 50 S13.0D . .33.00 48.00 .41 20 36 m 79.00 52 00 44 50 90 00 179 00 MODEL 001 002 003 004 005 006 007 DESCRIPTION 2BV 1 2 6A Id 30V 1 2 6A 36V«23A 40VS2 6A 24I/126A 26VK23A ISVI2SA 53V < 2 BA MATCHING PRICE TA-8O0 MK2. TA-802, TA-820A, TA-10OOA. TA-1500 S 27 00 Ift-503. IA-313A TA-400. TA-300, TA-377A 22,00 TA-477 ... 2BO0 TA-UOMK!- TR-355B TR-3S5A TA-3600 22 00 15 00 . ... 15.50 ...43.00 > c Q c CO 87 VM aoctpt rr^N Crwi.rCan3i Uonef Oi tjtrr* c>«ch» o«3 c O o OrcUrn COD tmhSSOO 1 MAnwnwdrffrisS^OO' • Vie *hip Uy uPS flfowix) ms** US i*r\M « Wj jno 4hip Of us. min Business 8 Showroonn hours: (Pacific Time) outMWUSn«4iHciMi oL*utoa*parm-mfiit&Qitm%ii!tt><2ioi o'kxtoQn'O'tbii ■M^M-^B«flijn.i5itrjwa»iMy»»i* *fifM-*?n[5 Mori Thru Pr i 9 : 30 am to 5.00 p-m of ca o*asc add uwM. Tfu 6 ?5V * Aft nnncwn fl*M tt v&* v* mtffet to w t*g Pnc« jv*» wbfoo. (o cnar»?9 wtonA pm itt* Wt w* r& imQorvJfr te tfpoQftf*M w Etc. Dealers Wanted - Quantity Discounts COD'S - VISA - MC . Discover ■ American Express All Orders and Free Catalogs Cabie Specialists, Inc. East Coast - Canada West Coast (800) 334-9494 (800) 666-9494 17SJC I Pnimlii! Blvd., Ste 431 3339 Sheridan Street, Ste. 112 NmrUi, CA MSB tMvvmm, a 3308. MASTERCARD AND VISA are now accepted for payment of your advertising. Simply complete the form on the first page of the Market Center and we will bill. BEST BY MAIL Rales: Write National, Bon 5, Sarasota, FL 34230 OF INTEREST TO ALL SHOP BY MAIL Catalog S5: Gilts N Things, Box 234, Sic, 1A 50583. LOW INTEREST VISA. Free application. Box 16801 (REI. Jacksonville Florida 32245-6601 CIGARETTES 30 CENTS Pack. Sources S2.00. IRWIN. Box 20961EE), Baytown, TX 77522-2096. GUARANTEED LOAN SI PERSONAL. Business. Credit Check! Prompt. Professional. (212)323-8006. No PERSONAL-MISCELLANEOUS ROMANTIC INTRODUCTIONS. CONFESSIONS. Fan t as lee. Secrets. All Lifestyles. 1-900-FUN-1990. $1.95 minute. 7 * * * * PRESENTING * * * ft CABLE TV DESCRAMBLERS ***** STARRING ***** JERROLD, HAMLIN, OAK AND OTHER FAMOUS MANUFACTURERS • FINEST WARRANTY PROGRAM AVAILABLE ■ LOWEST RETAIL I WHOLESALE PRICES IN US ■ ORDERS SHIPPED FROM STOCK WtTHIN 24 HRS • ALL MAJOR CREDIT CARDS ACCEPTED FOR FREE CATAtOC ONLY 1-800- 3 4 5- 89 2 7 FOR ALL INFORMATION 1-818-709-9937. s ^V SM0KET I Letfc close the book on forest fires. PACIFIC CABLE CO., INC. 7325V2 Reseda Blvd., Dept.2105 Heseda. CA 91335 j TV DESCRAMBLER LIQUIDATION! FREE CATALOG! Hamlin Combos $44, Oak M35B $60 (mln. 5), ate. WEST COAST ELECTRONICS For Information: 818-709-1758 Catalogs & Orders; 800-628-9656 ZENITH & TOCOM SPECIALS SUPER Zenith {Z-TAC) converters (w/flash- guard}... $179.00. Zenith "turn-on" module... $49.00. Tocom 5503(A) converters... Call. Tccom (5503- VfP 5503(A); 5507) -turn-on'' chips... $49 00. Tocom 5507 & Jerrold (security screw removal tool). ..$22.00. CINEPLEX VIDEO GROUP, 1 (800) 726-4627. CABLE BOXES BELOW WHOLESALE GUARANTEED STOCK - COD'S ■ DESCRAMBLERS • (QTY) (10) (20) (50) (100) TB 2-3 45 40 36 33 SA3-B 45 40 36 33 XN12 + 43 38 34 29 SB 2-3 43 38 34 30 60 CH REMOTE CONV/DECODER DRX-DIC 90 75 70 65 SYL DIC 75 60 50 45 • CONVERTERS W/REMOTES ■ Efr AUTOMOTIVE iT5[.4 Puttlit Service of This -Wajfoiinf "^^[^ J o*tm & The Advertising Council '*JM* «^T<- IS it true... jeeps for $44.00 through the U.S. gov't? For facts! (504) 649-5745 ext. S-5192. PANASONIC TZPC14S 5 YR. WAR. + PARENTAL + 86 CH TIMER + MEMORY + CH 2 OR 3 + NEW 70 65 61 57 REFURB 60 CH W7REMOTE S-4040 38 36 34 31 HAMLIN-ZENITH-TOCOM-CALL IT IS NOT THE INTENT OF LAKE SYLVAN SALES TO DEFRAUQ ANY CABLE "ELEViSlON OPERATOR FEDERAL AMD STATE LAWS PROVIDE SUBSTANTIAL PENALTIES FOR THEFT OF CABLE TELEvlSlQr* SERVICES LAKE SYLVAN SALES, INC. SORRY. NO MINNESOTA SALES 800-800-4582 DESCRAMBLERS PLUS! CIRCLE 187 ON FREE INFORMATION CARD ^ ^ 12" Subwoofer Box 12" Pioneer Subwoofer 800 Hz Horn The perfect high volume cabinet for dual voice coil subwoofers. Box comes with pre-cut wooter and port holes. Cabinet volume: 2 cu. fl. with dual ports. Charcoal carpet. Dimensions: 13"(H)x13' (D)x30"(W). Mel weight: 29 lbs. fjrjj PIONEER' 12" super duty, dual voice coil subwoofer. 30 oz. magnet, 2" voice coil. 100 watts RMS, 145 watts max power handling capability. 8 ohm impedance (4 and 8 ohm compatible). Sensitivity: 89dB1W7tM. Response: 25-700 Hi. QTS= .31, VAS= 10.3 cu fl. Net weight: 6 lbs Pioneer #A30GU30-55D. Piezo midrange/tweeter driver unit. Response: 800-20 KHz. Power handling capability: 20-30 volts (approximately 50 waits RMS). Sensitivity: 93 dB. 2.83W1M. 4" round. Motorola #KSN1 086. #RJ-270-085 $25 30 $23 95 C #RJ-260-495 $59 9 E ° aC h #RJ-290-145 $39*° $36 80 (1-3) (4-up) 18" Eminence Woofer Professional driver for use in auditorium and studio sound systems. Giant 100 oz. magnet. 250 watts RMS, 350 watts max power handling capability. Is= 30 Hi, QMS= 3.17, QES-. 373, OTS= .33, VAS= 10.5 curt, SPL.95dB1VW1M. Net weight: 29 lbs. #RJ-290-200 I (1-3) (4-up) 5-1/2" Cone Mid range EMINENCE $99«> $93 40 (1-3) , (4-up) 12" Pyle Woofer ^ - pyLE 12*. 70 oi. magnet woofer. 2-iffl' voice coil. 1 05 watts RMS, 155 watts max power handling capability. #RJ.292-050 $62»$59 80 #RJ-281-100 Original Sanyo high end system midrange. Large 5" paper cone with gold look dust cap. Heavy 12 oz. magnet. 1 ■ ferr o fluid cooled voice coil. 50 waits RMS H 75 watts max. Sanyo pari *Si2HiO. Netweight: 1-1/2 lbs. / SA*YO $5- $3 95 11-5) (6-up) (1-9) (10-up) Subwoofer Crossover Network Super duty. 200 watt RMS power handling capability. Designed specially for dual voice coil subwoofer systems. 12 dB per octave roll-cfl at V. ^-^ . 150 Hz into B ohms. Crossover also features a set of outputs tor use with your existing speaker system Network, is totally passive, requiring no power source o( its own. #RJ-260-220 $28 M $24 95 (1-5) (6-up) Parts ^ ■15 day money back guarantee ■ E 15.00 minimum order ■ We accept Mastercard. Visa, Discover, and C.O.D. orders, • 24 hour shipping ■ Shipping charge ■ UPS chart rate + Si. 00 ($3.00 minimum charge) ■ Hours 8:30 am - 7:00 pm EST, 340 E. First St.. Dayton, Ohio 45402 Monday - Friday • 9:00 am - 2:00 pm Saturday. Mail order Local: 1-513-222-0173 FAX: 513-222-4644 CALL TOLL FREE customers, please call for shipping estimate on orders exceeding 5 lbs. 1 "OQ0"OOQ"0531 Foreign customers please send £5.00 U.S. lunds lor catalog postage. FREE CATALOG > a c 0r> 2 CIRCLE 56 ON FREE INFORMATION CARD 89 msssmmm _^^^ m Converters, Remote Lontrols „ontrols, Descrambters, CD Players. JERROLD-OAK-SCIENTIFIC ATLANTA-HAMLIN ZENITH MANY MORE CALL TODAY! V Only qua! ity products sold V Easy to use vSatis faction guaranteed V Knowledgeable sales staff V Most orders shipped within 24 hours CALL FOR YOUR FREE CATALOG 1-800-228-7404 MAKE THE CONNECTION WITH 1S1U-TEK ELECTRONICS ll 51 14 Bakones Wood Dr.#307 Dept298 Austin, TX, 78759 EDUCATION & INSTRUCTION F.C.C. Commercial General Radiotelephone li- cense. Electronics home study. Fast, inexpensive! "Free" details. COMMAND, 0-176, Box 2824, San Francisco, CA 94126. COMPLETE course in electronic engineering. Eight volumes. Includes all necessary math and physics. Free brochure. BANNER TECHNICAL BOOKS, 1203 Grant Avenue, Rocktord, IL 61103. HIGH MONTHLY •RENTALS* If you find a bcuer deal, We'll beat it! JERROLD • TOCOM • HAMLIN • OAK • SCIENTIFIC ATLANTA - ZENITH • ask about our warranty pronram C.O.D. Visa, M/C, AM. EX. welcome. FREE CATALOG • FREE CALL • OPEN SAT- URDAYS GTV 1464 Garner Statiun Blvd #315 Raleigh, NC 27603 1 800 328-01 98 PAY TV AND SATELLITE DESCRAMBLING ALL NEW 1991 EDITION Our besi ye;. The very lates! in deMram&Jiiitf circuits, bypasses, itim-ons. for cablrf. wifeless arnl saletfitfl. QflEy $14.95. CMhtr pay TV editttois. VW. 1 (Basics c-1 a: ! Syssemsf Si 4.95. 19S9 Edition $14.45. Bu.'s saieiht* syslems under $600 $12.95. Wireless Cable Ha^dta* S3.95. Any 3/S29.95 « 5/$44 95. Scrambling News Monthly has all Info on lha new "Plain tonilla" descramblers which em- ulate B-Mac. VCIF, Plus and Orion. 5 ' 9.9S'y AH new eaialog S1 Scrambling News, 155? Herte! Aire.. Butlalrj. NY. 14216 COD'S ARE OK. (716) 874-208S YOUR HOME THAT HAS A SIMPLE SOLUTION. Call 1-800-SOS-RADON to get your Radon test information. SEPA JM CtJUKll o z o rx r- o LU o Q < EC UNICORN - YOUR I.C. SOURCE & MUCH, MUCH MORE! Laser Diode • Output: 3 mW (max.) Laser Diode (visible-red) * Current -55-100 mA {visible red) „ to ' °P- Volt: Z.3-3.0V a. W— = p\. ♦ Wavelength: 670NM fa Y\. I I £~ ' Lerls Required ' L r^ Vafc^gl ■ Data Sheet S ^"— ^8» '• :■ i - I ■: ; i ! '■ i I ■ 01 t ■:■ ■ ll STOCK # LS9200 Collimator Pen (Infra-red) PRICE $49.99 STOCK # LS022 • Output 1 : 5 mW {max.) * Current: 65-100 mA - Op. Voll .: 1-75-2.2^ • Vfave.englh: raONM * Lens Required ■ Data Sheet & Application notes inc, PRICE $19.99 Laser Diode {visible red) STOCK # SB3200 ■ Oulpul 4 mW [max.] ■ Current: 20 mA • Op. Vol..: 2 3-30V • Wavelength: 6T0NM * Lens Required * Data Si ■..■!_-■ •& Applicaiion noles Inc. PRICE $89.99 STOCK # LS9211 »Outpul:5rnW(maK.f * Currant: 60 mA * Op. Vol! : 2.3-3.QV » Wavelength: fiTONM • Lens Required • Data Sheet A Application notes imc PRICE $69.99 STOCK # LB 1052 • Oulput: 2.5 mW \max..\ • Cuirenl: 90*150 m A • Op- Volt; Z2-2.5V • Wavelength" B20MM • Data Sheej -'.: PRICE $39.99 Laser Pointer • Output: 3.5 mW ■ Wavelength: 670NM • Power Supply 2xAAA Salteries (included) « Beam: Appro*. 3" @ 100 yards Quanlily Discounts Available Power Supply STOCK* LSPOINT PRICE $199.99 STOCK ft PS1003 » Input: 115/230V 1 Outpul: -5v @ 3.75A -12v@ 1.5A -!2v@.4A • Sua: 7" L x 6W W X 2V H PRICE $19.99 Disc Drive & Computer Cleaning Kit Not just a drive cleaner- bul a complete computer cleaning kit. Includes swabs, nead cleaning riuid, anil- static cleaner, screen wipes and cleaning diskette. Disc Drive Head- Cleaning Kit Includes cleaning tluid and head- cleaning liu;d Anti-Static Screen Wipes For sialic -sensitive ~~T applications. Dispenser i— ^ packs, individually wrapped. 1702 2709 2716 2716-1 TMS2716 27C16 2732 2732A-2 2732A 2732A-4 TMS2532 TMS2532P 27C32 276420 2764 2764A-20 STOCK # SB 1099 SB1100 3W 5V." Kit Kit PRICE $6.99 $6.99 STOCK ft SB1105 3'A" Drive Kit SB 11 06 5 1 /." Drive Kit PRICE 51.99 $1.99 STOCK fj PRICE SB1104 SB1106 ir7£4* I ^h .g y Dispenser pack ot 25 wipes Dispenser pack ot 100 wipes CORN CT I ON ICS 10010 Canoga Ave., Unit B-8 ■ Chatswortti, CA 91311 OUTSIDECALIFORNIA: (800)824-3432{OrdersOnly) IN CALI FORNI A: (81 8) 341 -8833 ORDER BY FAX: (818) 998-797S Minimum Order S1S.0O • 24-hour ordering available MK4027 4115-120 4115-150 411S-20O 4116-250 41S4-10O 4164-120 4164-150 4164-200 4416-120 4416-150 STOCK # SB1053 • Outpul: 3mW (max.> • Current: flS-iOG mA • Op. Volt.: 2.3^3.QV • Waveler-glh' S20«lv. ■ Lens Requrred ■ Data Sheet inc. PRICE $9.99 EPROMS 1-24 25-99 100» STOCK ■ 1-24 25-99 100' 4.59 649 3.29 3.79 5.79 399 4.19 3.79 3.69 3.19 5.79 1.99 3.79 4.29 3.99 3 99 4.36 6.17 3.13 3.60 5.50 3.79 3.9E 3.60 3.51 3.03 5.50 1.89 360 4.06 379 3.79 3 92 5.55 2.82 3.24 4 95 3.41 3.58 324 3.16 2.73 495 1.T0 324 3.67 3.41 3 41 2764A TMS2564 27C64 27128-20 27128 27128A 27C128 27256-20 27256 27C2S6 27512-20 2TS12 27C512 2TC1024 5B764 86766 3.49 5.79 3.29 4.93 4.79 4.79 4.79 529 4.79 429 6.49 5.99 5.99 12.99 13.99 12.99 3.32 2.99 5.50 4.95 3.13 3.28 474 4.27 4.55 4.09 4.55 4.09 4. 55 5.03 4.55 4.06 6.17 5.69 5.69 4.09 4 53 4.09 3.67 5.55 5.12 5.12 12.34 11.11 13.29 11.96 12.34 11,11 DYNAMIC RAMS 1-24 25-99 100t STOCK" 1-24 2599 100' ,56 1.32 .94 .85 .56 1.80 1.61 1.51 1.32 1.89 1.70 50 4464-100 113 4464-120 .85 4464-150 77 41255-60 50 41256-80 1.63 4125S-100 155 41256-120 1.36 41256-150 1 19 511000-70 1.70 511000-80 1.53 511000-100 2.99 279 2.29 299 2.64 2.65 2.13 2.84 2.56 2.39 196 2.56 2.39 1.99 1.89 1.70 1.69 i.ao 1.63 1.79 1.70 1.53 6.49 6.17 5.55 5.99 5.69 5.12 5.49 522 4.70 90 CIRCLE 178 ON FREE INFORMATION CARD KELVIH. Electronics discount Center LED CENTER IPROJECT PARTS MULTIMETERS ^BREADBOARDS! RESISTORS ^Kl .Mplo ill! 11 liiiii 11 l: 1 :.'■ :■':::; ' ' " i | 1 ji J 1 1 III!' 1 ' \v I !■ m KELVIN PRO 400 KELVIN DIGITAL MULTIMETERS kelvin 100 Basic s 19. 95 KELWW150 Basic+ *29. 8S with Transistor Hie Test KELW/v^OO Advanced ...*39. M w.Transistot Hie, Capacitor Test kelvin PRO 4(30 J 69. 55 WiTranslslor, Capacitor, AC DC Test, L-ri-qn- 20 MHz Freq Counter. Durable Kelvin Meiers backed by a 2 Yr Warranty - Parts a Labor Protective Case *4. M For Model 100. 150. 200 Protective Case 'g. 85 6B009S Slock Ho. Post Contacts 680093 500..., z 4 680097 680098 680100 680100 VCH4RQOST ,' 4. 25 840 s 5. ss 1380 Ml. 75 For Model Pro o 91 CIRCLE 191 ON FREE INFORMATION CARD Perfectly Tuned for Test/Measurement and Prototype Equipment 51 -Piece Electronic Tool Kit Tools Included in Kit: 10' measuring tape 5.25* needle nose pliers Electric tape Ulilily component box 6 piece precision screwdriver set 6" long tweezers 8 piece hex key wrench set 7" brush and scraper Digital Multimeter Brush 7" line point probe Round needle file 1 piece screwdriver set: 6 Stalled & 4 Phillips 7" slotted probe Flat needle file 4.5" diagonal cutting pliers Global Specialties Protoboard® Design 6" adjustable wrench 3D Wall soldering iron 5.5" Siainiess sieel scissors Soldering stand Rosin core solder 5.25" Flal nose pliers Utility knife wilh extra blade Desoidering pump 5.25" Bent needle nose pliers Carrying case: t7.63*Wx12,5"Dx3.5 - H MS305 $1 19.95 Jameco Logic Pulser: Jameco Logic Probe • Compatirjls Willi TTL, DTL. RTL, HTL, HNtL, MOS ant) CMOS ICs ■ 1Mii Sync input impedance • Pulser mode output current: 10mA ■ Square wave current output: 5mA ■ Audible rone LP540 ..$16.95 Prototype Products Jameco Soldertess Breadboards -CXs Pin Dim. No. L" x W Contact Binding . Max Frequency 90MHz ■ Minimum detectable pulse: ir:-:. ■ 120Kti tnpul impedance - Max. supply voltage: --25V • TTL threshold: (Lo).O.ev i0.1V (Hi) <^.3V --0 2V ■ CMOS threshold: (Lo)30% VCC ;10% (Hi) 70% VCC i10% MS104 $24.95 Metex Digital Multimeters General Specs: ■ Handheld, high accuracy ■ AC/DC voltage, AC/ DC current, resistance, diodes, continuity, transistor nFE * Manual ranging vi> overload prelection M36S0 ,. M4650 only: * Also measure Irequencjr and capacitance M4650 only: ■ Data hold swilch ■ 4,5 digit JEZ1 JE23 JE24 JE25 JE26 JE27 3.25 X 2.125 6.5x2,125 6.5 X 3.125 6.5 X 4.25 6.875 X 5.75 7.25 s 7.5 400 830 1,360 1,660 2.390 3.220 $4.95 $6.95 $12.95 $17.95 $22.95 $32.95 J AMECO 24 Hour Order Hotline (415)592-8097 VISA MMC , . HtHIM Please refer lo Mail Key 2 when ordering M3610 3.5 DjgitMulIimeler $59.95 M 3 650 3 5 Digit Multimeter w.'Frequency & Capaciisnte $74.95 M4650 4.5 Digil w. frequency . CapaalanoG and Bala Hold Smith S99.95 Handheld Multimeter Features: ■ Ideal for analog, digital and microprocessor circuits ■ Triple DC regulated power supplies, +5V, +15V, -15V • 8 logic indicators • Function generator with sine, square, triangle and TTL waveforms ■ Two debounced push-button switches ■ Two SPDT slide switches, all leads available and uncommited ■ A total of 2520 uncommited tie-points • Potentiometers: onelKnandonel 0KI2 ■ Includes power supply, instrumentation and breadboarding PB503 $299.95 Soldering and Desoidering Stations 60 Wat! Analog Display Soldering Station ■ Electronic temperature control from 200° to 878" F ■ Cartridge heat- ing element for a longer life of the soldering tip XY1683 $69.95 30 Watt Electronic Temperature Controlled Desoidering Station • Electronic temperature control from 212° to 842°F • Self contained high rotary vacuum pump XY999 $299.95 A.R.T. EPROM Programmer • Programs all current EPROMs in Ihe 2716 to 27512 range plus the X2864 EEPROM • RS232 port • Software inciuded EPP $199.95 UVP EPROM Eraser r J ■ Erases al! EPROMs - Erases 1 chip in 15 minutes and 8 chips in 21 min ■ LtV intensity: 6800 UW/CM 2 DE4 $89.95 jT$£ ■ 3-5 digil LCD wiln automatic polarity indication * AC/DC voltage measurement up lo 50D volts • AC DC current measurement up to 200mA ■ Resistance measurement up lo 20M1 * Con- tinuity checker with audible tone - Diode and logic tesler ■ Aulo'manual range and dala hold functions * All range protection and (unction in- dications DMM905 $39.95 EPROMs - for your programming needs Part No. Price ' Part No. Price TMS2516 TMS2532-35 TMS2532A TMS2564 TMS2716 1702A 2708 2716 2716-1 27C16 2732 2732A-20 2732A-25 2732A-45 27C32 $4.25 9.95 7.95 5.95 5.95 3.95 4.95 3.49 3.95 4.25 4.95 4.95 3.49 2.95 4.95 2764-20 2764-25 2764-45 2764 A-20 2764A-25 27C64-15 27C64-25 271280TP 27128-20 27128-25 27128A-15 27128A-20 27128A-25 27C128-15 27C1 28-25 $3.95 3.75 3,49 3.95 3.25 3.95 3.25 2.95 6.95 7.95 5.95 4.49 3.75 5.95 7.95 Part No. Price 272560TP $3.75 27256-15 5.95 27256-20 5.25 27256-25 4.75 27C256-15 5.95 27C256-20 4.95 27C256-25 4.49 2751 20TP 4.95 27512-20 6.95 27512-25 5.95 27C512-15 6.95 27C512-20 6.49 27C512-25 5.95 27C010-15 11.95 68766-35 9.95 92 ■ Partial Listing Over 4000 Electronic and Computer Components in Stock! CIRCLE 114 ON FREE INFORMATION CARD Top Performance Computer Products and Electronic Components Assemble Your own Computer Kit! Jameco 16MHz 80386SX Desktop Computer Kit ■ Building your own computer provides you with a better understanding of components and their functions ■ In-depth assembly instructions included ■ Have your new computer assembled and running in an evening, using common tools • Software included ■ Purchase computer kits configured by Jameco or design your own J AMECO ^^ ELECTRONIC COMPONENTS COMPUTER PRODUCTS 24 Hour Order Hotline (41 5) 592-8097 $949 .95 -' "' - •■- • JE3816 isUapW ' muni""' 1 Jameco 1 6 MHz 80386SX Desktop Computer Kit Includes: ■ 80386SX Motherboard with 2MB RAM (expandable to 8MB) • 101 -key enhanced keyboard • Multi I/O Card • Toshiba 1.44MB, 3.5' 1 DSHD floppy disk drive • Baby sized desktop case - 200 Watt power supply • DR DOS 5.0 by Digital Research and AMI diagnostic software mzm Relisys14" VGA Color Monitor ■ Max resolution: 720 x 480 ■ Bandwidth: 30MHz •Input: D B 1 5-pin (analog) RE9513 $399.95 Jameco 16-bit VGA Card Integrated Circuits Part No. 1-9 iPt Part No. 1-9 19+ 7400 S.29 $.19 7472 $1.95 $1.75 7402 .29 .19 7473 .45 .35 7404 .29 .19 7474 .39 .29 7405 .35 .25 7475 .49 .39 7406 .39 .29 7476 .45 .35 7407 .39 .29 7483 .69 .59 7408 .35 .25 7486 .45 .35 7410 .29 .19 7489 2.95 2.75 7411 .35 .25 7490 .49 .39 7414 .35 .25 7493 .45 .35 7417 .35 .25 74116 1.19 1.09 7420 .29 .19 74121 .49 .39 7427 .35 .25 74123 .49 .39 7430 .35 .25 74125 .49 .39 7432 .39 .29 74151 .39 .29 7438 .45 .35 74160 .59 .49 7442 .49 .39 74161 .69 .59 7445 .75 .65 74192 .79 .69 7446 .99 .79 74193 .79 .69 7447 .89 .79 74194 1.19 1.09 • Supports VGA, EGA, CGA, MDA and Hercules modes * Comes with 256KB video RAM upgradable to 512KB (eight 41464-100) • Capable of 640 x 480 with 256 colors, 800 x 600 wilh 16 colors VG20 00 $149.95 Miscellaneous Components Potentiometers Values available (insert ohms into space marked "XX"): 5001J. 1K. 5K, 10K, 20K, 50K, 100K, 1MEG 43PXX 3 /4 Watl,15 Turn $.99 63PXX 'ft.Watt, 1 Turn , ,.$.89 PN2222 PN2907 1N4004 Tra $.12 .12 10 25 nsistors And Diodes 1N4735 $.25|2N4401... 2N3904 12J1N4148... 1N751 1S'2N3055... ..$.15 .. .07 69 2N2222A .. C106B1 5911 N270 25 Dynamic RAMs 4164-100 lOQns.&iKil $1.95 41256-100 100ns.266Ki l $1.99 4164-120 120ns, WK * 1 1.89 41256-120 120ns, 256K 1 1 1.89 4164-150 150ns, MKxl 1.S9 41256-150 150 ns. 25SKi 1 1.85 41256-60 fflns, sSBKii 2.75 511000P-80 Sftns. IMBxi 7.95 41256-80 80ns. 356K 1 1 2.49 ! 51 1000P-10 100ns. IMBxi 6.95 ■ Call tor a complete listing ol IC's Switches JMT123 SPDT, On-On [Toggle) $1.25 206-B SPST, 16-pin (DIP) $1 .09 MPC121 SPDT, OnOftOn (Toggle) $1.19 MS102 S PST, Momentary (Push-Button ) $.39 D-Sub Connectors and Hoods DB25P Mala. 25-pin $.65|DB25H Hood $.39 DB25S Female , 25-pin . . . $.75 1 LEDs XC209FtTi.(Red) $.141 XC556R T1 3 rt. (Red) ...$.12 XC556G T1 3 /4. (Graan} .. .1 6 1 XC556Y T1 3 rt. (Yellow) .. .1 6 IC Sockets Wire Wrap (Gold) Level #2 8WW $.49 14WW 69 16WW 79 24WW 1.15 28WW 1.39 40WW... 1.89 Low Profile SLP $.11 14LP 12 16LP 13 24LP 19 28LP..... 22 40LP 28 Soldertail Standard & Header Plug Sockets Also Available ^ Hard Drives Conner (16-bit IDE) CP3044 40MB 3.6' Low Pralite $399,95 CP31 84 BOMB 3.5'HH $599.95 CP3104 10OMB 3.5-HH $649.95 A DP20 Host Adapter, $29.95 Look to Jameco ■ Wide selection of integrated circuits and components • Quality prototype and test equipment • Computer kits and accessories Additional items that Jameco offers: • Tools ■ Cables ■ Connectors ■ Data Books ■ Motherboards • Memory • Math Coprocessors - Computer Accessories • Power Protection Equipment • Much, much more ! Let us show you what we have to offer; call or write for the latest Jameco catalog! $50.00 Minimum Order Data Sheets - 50c each Call for a FREE 90-Page catalog! © 1991 Jameco Eleclconics ftfSI CA Residents Add 6.00%. 6.50% or 7.00% Sales Tax Shipping, handling and insurance are additional. (Costs may wary according to weight anO shipping method) Terms: Prices subject lo change without notice. Items subject lo availability and prior sale. Complete lis! ol termsvrarranlies is available upon request IBM is j reguierKS Irartomai* a' Mameeonel Budneft Machine* J AMECO ® ^^ ELECTRONIC COMPONENTS COMPUTER PRODUCTS FAX: (415) 592-2503 (415)595-2664 1 355 Shoreway Road Belmont, CA 94002 • Customer Service -Technical Assistance • Credit Department • All Other Inquiries ■ (415) 592-8097 ■ 7AM -4PM P.S.T. CIRCLE 114 ON FREE INFORMATION CARD 93 We Have QUALITY PARTS • We Have DISCOUNT PRICES * We SHIP FAST mmMmtm><&im Highest Quality Metal C-60 Cassettes (Erased) Premium quality meia! tape in C-60 cassettes (30min. per side). One of the l i nest "brand-name" lapes on :hu market, in durable, clear pfastic 3 ran sport mechanisms. Recorded and bulk erased, [he record-protect labs have been removed and therefore, need lo be taped over to re-record. Audiophiles wilt ap- preciate the wide dynamic range of this tape, K your cassette deck has a "melaT setting you will hear l he deference. A real bargain! CAT#C60M 11.25 each- 10 for St 0.00 TOUCH DIMMER when connected to any lamp, will turn i[ on and off and change the brightness level when any metal part is touched. We donl have the wiring harness that originally connected this to the tamp, but we can provide a simple hook- up diagram and instruction sheet. The solid-state circuitry is contained in a thermo- plastic box 1,91" X 3.1 r X 0.635-. CAT#DMR-1 $3.50 each INFRARED SECURITY LIGHT (AS-IS) Electriko t SiL- 101 - Experiment with infrared sensors with these outdoor Security lights. Contain lots o( interesting components, and IR detector, photo resistor, relay, transformer. EC'S, vofUge regulator, capacitors, Irimpots and other goodies. Returned to the distributor for variety of reasons, we've round that most, of them work lo some extent. We don't want to test them and would prefer to sell them "as-ts" at a greatly reduced price. Mounts lo any standard electrical junction box. Enf rared sensor detects movement up to 65 feet and turns on lights. Sensor can be adjusted for sensitivity and duration ol lighting. The position of the sockets and the in! rared sensor can be easily adjusted. Will handte two 150 watt PAR 33 lamps. Suhable lor wet locations Bulbs not inctuded.CAT* IL-101 S7.50 each SWITCHES Dip P.C. Pushbutton ITT Schadow Digriast Series SE jCj S.P.D.T. momentary JaS?~3 pushbutton. Mounts In v^3fT 14 pin DIP conliguralbn. Designed lor tow current switching appli- caiions. Grey keycap is 0.6B" X 0.67". CAT#PB-2S SI. 00 each to lor $9 50 ■ 100 tor 185.00 Pushbutton Switch ^^^ SMK Manufacturing ^?¥^) 0.47" squa/e black pushbutton, * 4 *Ijri SPST normally open. 4 p.c. pins for mounting, Ideal lo: tow current switching applications. CAT* PB-2B 5rorS1.00-10OlorS15.tW Rotary BCD Switch r^\ EECO * 2310-02G lijwjj BCD 10 position V— 1 rotary switch. DIP configuration fits in standard 3 pin I.e. socket. Right angle style. Screwdriver actuation. 0.4? cube. CAT#RDIP-2 $1.75 each 10 for S16.00 ■ 1 00 lor $145.00 Miniature Toggles Rated: 3 amps @ 120 Vac S.P.D.T, (ON-ON) P.C. mount c AT* mts j) PC $ i .00 each a 10 lor $9.00- IOOforSSO.00 J S.P.D.T, (ON-ON) solder lugs „fe CAT*MTS-4 S1.35each Eg 10 lor $12.50- 100 (or $110.00 ^r D.P.D.T. (ON-ON) solder lugs CAT#MTS-8 $1,75 ea. 10 lor $15.00 D.P.D.T. (ON-ON) P.C. mount CAT*MTS-8PC $2.00 oa. 10 lor $17.50 TELEPHONE KEYPAD 12 button l el op hone Keypad. Ivory finish. 2.fl3-x 2.2" x 058' thick. Matrix encoded. Ideal for telephone or security keypad. CAT *KP"MS 1.00 each 10forS9.00 OPTO-SENSOR TRW/Optron # OPB 5447-2 IR emitter/ sensor pair in r -j"^ Rectangular package with A'f^^rj) 23" color coded leads. CAT#OSR-* 2 tor St. 00 PHOTOFLASH CAPACITOR Rubicon CE 210 Mfd 330 Volt photoll ash capacitor. 0.79" die, I > X 1,1" high. These are new capacitors that have been propped with 1 .4" black and red wire leads soldered lo the terminals. CAT* PPC-210 $1.25 each- 10 lor $11.00 100 for $100.00 Large quantities available. Call for pricing. RECHARGEABLE BATTERIES 6 Volt 1 Amp/Hour Japan Storage Battery Co. Portalac ss-J^ * PE5V1 S?"7> 6 Volt i Ah p J/| rechargeable \ J sealed lead-acid — — \s (gellcell). 2" X 1.S35 - X 2" ht. Batteries are propped with 5" black and red leads terminat- ed with Spin connector. CAT#GC-6i $4.75 each 10 for $42.50 Nickel-Cad AAA SIZE $1.50 each 1.2 volts 180 mAh CAT* KCB-AAA A4 SIZE $2.00 each 1.25vo1ts500mAh CAT# NCB-AA AA SIZE $2.20 each WITH SOLDER TABS CAT* NCB-SAA CSIZE $4.25 each 1 .2 volts 1200 mAh CAT* NCB-C DSIZE $4.50each 1.2 volts 1200 mAh CAT* NCB-D HALL EFFECT SENSOR P.C. RELAYS c= Microswitch *SS4t Tiny, solid state switch reacts Instantly to proximity of magnetic field. Operates at extremely high speeds, up to 1 00 khz. Case si:e: 0.1 f X 0.1 7" X 0.06" thick. 4.5 Vdc to 24 Vdc supply voltage, 10 ma. sink type digital output. Operating gauss - 1 5 to 40. P.C. leads. CAT* HESW-2 75e each ■ 1 for $6.50 1 00 for $60.00 • 1 000 lor $500.00 3 1/2" DISKETTES Quality, double-sided 3 1/2" diskettes. These diskettes were recorded. but never used. Flip the write-prolect tab lo oil position and use lor your own data storage at a fraction of the cost of new diskettes, CAT#DTS-1 SI. 00 each ■ 10 lor 59.00 AUDIO SLIDE POT Dual 1K audio. 3 1/2" long. 2 V2" slide CAT#ASP-1KD Reduced lo 50c each 100 lor $40.00 I.E.C. POWER CORD 6 foot BLACK, SPH-3S6 jack to 3 prong mokJed A.C. plug. Fits most computers, computer terminals and lesi equipment. CAT*LCAC-C6 $3.00 each FLASH ASSEMBLY New compact flash assemby from a U.S. manufacturer of cameras. Operates on 3 Vdc and measures ^ 2 1/2" x 1 1/4". Ideal lor use as a strobe, warning light or attention getter. Includes hook-up diagram. CAT* FSH-i $3.75 each 10 lor $35,00 • 100 lor $325.00 H l J i £ The following relays all have p.c. pins for both input and output as well as quick-connect terminals on the output, l .5" X 1 .05" X 1.08". UL t CSA listed. 12 Vdc, SPDT Potter & Brumlield * T91R5D22-12-02 12 Vdc 155 ohm coil. Normally open contacts rat- ed 20 amps. Normally closed contacts rated 1 amps. CAT#RLY-31 $2.50 each 10 for $22.50 12 Vdc, SPST N. O. Potter & Brumlield # T91R5D22- 12-01 12 Vdc, 155 ohm coil, S.P.S.T. normally open con- tacts rated 30 amps. CAT* RLY-3Z $2.00 each 10 for $16.00 LE.D.'S Standard JUMBO Diffused T 1-3/4 size (5 mm) RED CAT* LED-1 10 lor $1.50- 100 lor $13.00 GREEN CAT#LED-2 10 lor $2.00- 100 for $17,00 YELLOW CAT* LED-3 10 lor $2.03 ■ 100 lor $17.00 FLASHING LED W.' built in Hashing circuit 5 vo II opera! ion . T 1 -3/4 (5mm) r^*-— - RED $1.00 each CAT* LED-* 10 lor $9.50 GREEN $i.00each CAT#LED-40i 10 lor $9.50 YELLOW $i.00each CAT* LED-4Y10lor $9.50 LED HOLDER Two piece holder. *» & CAT* HLED to for 65c A ; &* L.E.D. FLASHER KIT Two L.E.O.'s flash In ^i^ unison when a 9 volt battery is attached. This kit Includes a p.c. board, all the parts and instructions to make a simple flash- er circuit. A quick and easy project lor anyone with basic soldering skills. CAT*LEDKIT $1.75perkh L.E.D. CHASER KIT Build l his variable Speed led chaser, 1 feds Hash sequentially at whoever speed you set l hem for, Easy to build kit indudes pc board, parts and instructions. Idea] for special lighting effects, costumes, etc. Oper- ates on 3 to 9 volts. PC board is 5" X SL2ST, A great one hour project. CAT* AEC $B.5Q each STEPPING MOTOR CONTROLLER KIT Learn about stepping motors while > building this simple circuit. Includes circuit board, stepping motor and all parts except 12 Vdc power supply, CATflSMKIT Sifl.OGeach METRONOME KIT BPr^r© This simple device can be set to click from 20 lo 1,000 beats per minute. Easy to build, includes circuit board, all componenis and instructions. Oper- ates on a 9 voll battery {not included). CAT* METRO $3.75 each PHOTO RESISTOR 1 .000 ohms bright light. &* 16K ohms dark. Tl 0.182" dia. X .oe-high.0.18" long leads CAT*PHE-7 2 lor $1.00 100 lot $45.00 • 1000 lor $400.00 ORDER TOLL FREE 1-800-826-5432 FAX (818) 781-2653 • INFORMATION (818) 904-0524 Call Or Write For Our Free 64 Page Catalog Outside the U.S.A. send $2.00 postage for a catalog. Minimum Order SI 0.00 -All Orders Can Be Charged To Visa, Mastercard Or Discovercard • Checks and Money Orders Accepted By Mail • California, Add Sales Tax • Shipping And Handling $3.50 for the 48 Continental United States ■ All Others including Alaska, Hawaii, P.R. And Canada Must Pay Full Shipping • Quantities Limited • No C.O.D. • Prices Subject to change without notice. ss MAIL ORDERS TO: ALL ELECTRONICS CORP • P.O. BOX 567 • VAN NUYS, CA 91408 94 CIRCLE 107 ON FREE INFORMATION CARD GOLDSTAR - 20 MHZ AND 40 MHZ DUAL TRACE OSCILLOSCOPES GoldStar ■CRT S7020A SPECIFICATIONS Graticule Acceleration potential Z-axis input ■Vertical Oellectlon System Large 6" screen with internal graticule. 6x10 div (1 rjiir=i0 mm] with 0,10,90 and 100% markers Approximately 2kV Sensitivity: At least 5 Vp~p Polarity: Positive-going input decreases intsnsity Usable frequency range: DC to 2Mhz Maximum input voltage: 30V iDC, AC peak) Input impedance: 47Kfi(typl S7020A 2 Year Manufacturer's Warranty ■20Mtii Dual-Trace Oscilloscope The Model S7O20A is a utility oscilloscope thai features scale illumination and beam rotation capabilities, plus a 6" rectangular CRT with an internal graticule. The acceleration voltage is regulated to ensure accurals measurements. This model offers 5mV7div (20Mhz), ImV/div (7Mliz), artrj a maximum sweep rate of 100 nsidiv (x 10 MAG). <40Mhz Dual-Trace Oscilloscope The Model S7040A is a standard oscilloscope that lealures delayed sweep triggered function, signal delay lines, scale illumination and beam rotation capabiiilies, plus a high-brightness, aluminized 6- inch rectangular CRT with an internal graiicute. The acceleration voltage is regulated to ensure accurate measurements. This model offers 5mV/div (40Mhz). tmV/div [7Mhz), and a maximum sweep rate of 1 00 ns/div (x1 MAG). Shipping Weight Sensitivity and accuracy Bandwidth Rise time Max. input voltage Input coupling Input impedance Display mode Polarity invert Dynamic range 5mV/div to SV/rjiv t3% 1 calibrated sleps 1 mV/div to 1 Wdiv ±5% (when using x5 magnifier) Uncalibrated continuous variable control between steps at least 1 :2.5 with uncalibrated DC to 20Mhz (-3dB) When using x5 magnifier: DC to 7Mhz f-3dB) Approximately 17.5ns When using x5 magnifier: Approx. 50ns 300V (DCtAC peak) or 5MVp-p AC at 1kH2 AC. GND, DC 1 MCl approximately 30±5pF CH1 , CH2, ALT. CHOP. ADD CHS only a divisions or more •X-Y Operation Input Bandwidth Sensitivity Phase difference CH1 : X-axis CH2: Y-axis DC to 500kHz (-3dB) SmWdlv to 5V/div (ImV/dlv to tWdiv whan using XS magnilier) less than 3° at 20kHz ■ Horiionlal Deflection Syslem Time base (A) Maximum sweep rata -Trigger System 0.2us/div lo 0.2s/div ±3% Additional error for magnifier ±2% Uncalibrated continuous control between steps 1:2.5 IQOns/div (20ns'div and 50ns/div are uncalibrated) Order # Price Description S7020A 399.95 20 Mhz Dual Trace Oscilloscope 20 lbs. S7040A 699.95 40 Mhz Dual Trace vil Delayed Sweep 22 ibs. SP100 49,95 100 Mhz Probe Kit (Pair) , 12 oz. SP101 34.95 50 Mhz Probe Kit (Pair) 12 oz. Trigger mode Trigger source Trigger coupling Trigger sensitivity TV trigger sensitivity EXT I rigger inpul AUTO. NORM. TV-V, TV-H INT (CHI, CH2), LINE. EXT AC, HF REJ. LF HEJ. DC Frequency INT (CHI. CHS) EXT DC to 2Mhz 2 to 20Mhz O.Sdhr t.Sdiv 200mV 800m V INT: Sync pulse more than tdiv EXT: Sync pulse more than 1 Vp-p 30pF (Max. input vollage: 300V [DC to AC peak] at 1kHz) SOLDERLESS PROTOTYPING BOARDS MATH COPROCESSORS FEATURES •Color coordinates for easy recognition ■Insertion wire: 20-29 AWG (0.3 - 0.8 mm) •Over 10,000 insertion cycles -Accepts all standard components nnn SB830 SB1660 SB3220 Super Savings Special!! Order # EasyTech Order # SB200 SB400 SB630 SB830 SB 1360 SB1660 SB2390 SB322Q Price 1-9 2.99 4.89 5.49 6.43 12.49 17.49 22.49 31.49 Price 10+ 2.49 4.39 4.99 5.99 11.99 16.99 21.99 30.99 Dimensions (in.) LxWxH 6.5 x .37 x .4 3.3 x 2.2 x .4 6.5 x 1.4 x. 4 6.5 x 2.2 x .4 8.5x3,9x1.2 8,5x5.1 xt.2 9.1 x 6.9x1.2 9.5x8.3x1.2 Dist, Strips Dist. Points 100x2 100 200 100 400 500 700 Term. Strips Term. Points 300 630 630 1,260 1,260 1.890 2,520 Binding Posts EPROMS Order # Price THS2532 6.95 27CMJ 4.7S 2716 3.45 2716-1 3,95 2732 3.95 2732A25 3.45 2732B4S 4.25 2764-25 3.75 2764A25 3.25 27C64A15 3.95 27128A25 3.95 27256-25 4.75 27256-30 3.45 27C512-15 6.95 Prop. DRAMS Order # Price Desc. 25V 25V 25V 25V 25V 21V 12.5V 21V 12.5V 12.5V 12.5V 12.5V 12.5V 12.5V MK4027N2... .75 4116-20 85 4416-12 2.25 4164-10 1.95 4164-15 1.75 4164-20 1.25 41464-12 2.75 41256-80 2.75 41256-12 2.15 41256-15 1.95 51 4256-60. ...8.75 51 4256-10. ...7 .95 511000-60 .8.75 511000-10....8.25 4x1 16x1 16x4 64x1 64x1 64x1 64x4 256x1 256x1 256x1 256x4 256x4 1Mx1 1Mx1 STATIC RAMS Order # Price 2101 .1.65 2114L25 .1.15 2147-3 .3.75 2148-3 .1.95 2149-35...... .3.75 5101 ..3.95 6116LP3 .... ..2.95 6116-3 .2.45 6264LP10.. ..4.95 6264LP15 .. -3.95 6264-10 .4.75 6264-15 .,3.75 62256LP10 ,7.95 62256LP15 .6.95 MICROS Order | Price 8031 3.55 8080A 2.75 B085A 2.95 4.45 4.25 8237 AS 4.15 8250 5.75 8251 A 2.25 8253 .....1.95 8253-5 2.25 82SSA5 2.75 8259-5 2.25 8275 18.95 8284A 2.25 80C2B7A12 149.95 80387-16 259.95 83D87-16 279.95 83D87-33 469.95 Price Description Pins Intel 12Mhz 40 For 80286 CPU Based Laptops Intel 16Mhz PGA68 For 80386 CPU Based Computers Cyrix 16Mhz PGA68 For 80386 CPU Based Computers Cyrix 33Mhz PGA68 For 80386 CPU Based Computers Extensive range of parts & components in stock Call to reserve your free copy of our new 1 991 catalog due in late July imaumuuiimmwiMi 2917 Bayview Drive ■ Fremont, CA 94538 Order Direct: 1 -800-582-4044 Fax Direct: 1-800-582-1255 Monday- Friday, 7am - 5pm (PST) /10am- 8pm (EST) HviSA H MasterCard OJCOD-No personal checks, US funds ($5.00 charge) EluSPS HuPS GJAirborne Express Add 5% of total for ground shipping charges ($3.00 min.) 'California residents, add appropriate sales tax. *12 month warranty on ali EasyTech products. *30 day money back guarantee. "We reserve the right to substitute manufacturers. 'Prices subject to change without notice. CIRCLE 179 ON FREE INFORMATION CARD > C Q c