E Men a NOW TELEVISION IS TRANSMITTED

CB Power Mikes-PunchingYour MessageThrough

SEPTEMBER- OCTOBER FOR 1977 BEGINNERS $1.00 e men a NOW TELEVISION IS TRANSMITTED

AND RECEIVED e tir.'. OUR BASIC COURSE SPECIAL HOME COMPUTER ISSUE *How to Run a Computer Terminal inYour Home *Assembling the SWTP-6800 Microcomputer l Programming with the Hewlett- Packard HP -65 Calculator *Previewing Heath Home . Computer Systems

LAS VEGAS LE LetsYou Run Your Own Roulette

FLASH MA KeepsYour Camera Out r of the Dark

PLUS

J SCA Adaptor HEATH H.ME COI.APUTER CON PONENT3 s Hi -Fi DX 8 Digital Comp /ter f --- fig CRT Termina 0 HIS Papertape 11 ,rte Reader /Punch CB Test Reports 1_ Digital Com:uter s EC Writer II Ke -3oard u/ Antique Radio News Printer Termir al J And Much Much More! A DAVIS PUBL [>TION

www.americanradiohistory.com Read what the U.S. Dept. of Labor* says about these growing career fields:

1. Electricians.(Construction and Maintenance) In selecting apprentice applicants or trainees, employers look for young people who have GOOD JOBS FOR manual and are interested in learning SIX dexterity how electrical equipment functions. Appli- cants also need good color vision because electrical tiectriri.ur wires are frequently identified by color. Al- though physical strength is not essential, agility and good health arc important. Employment of construction electricians is expected to increase rapidly through the mid- 1980's. Employment of maintenance electricians is expected to increase moderately through the mid- 1980's because of the growing amount of electrical and electronic equipment used in industry. 2. Auto Mechanics. For entry jobs, employers look for young persons with mechanical aptitude, and a knowledge of automobiles. Generally, a driver's license is required. Courses in automobile repair offered by many high schools, voca- tional schools, and private trade schools are helpful. Courses in science and mathematics help a person better understand how an automobile operates. Employment is expected to increase because expansion of the driving age population, consumer purchasing power, and multicar own- ership will increase the number of automobiles.

3. Accountants. Greater use of accounting information in business management, changing tax systems, and growth of large corporations all point to excellent opportunities for accountants. People planning a career in accounting should have an aptitude for mathematics. Neat- .. and accuracy also are necessary. Employers ness...,..seek applicants who handle responsibility and work with little supervision. Employment of accountants is expected to increase rapidly through the mid- 1980's as businesses and government agencies continue to expand in size and complexity.

4. Engineering and Science Technicians. Industrial expansion and increasing complexity of modern technology underlie the anticipated increase in demand for technicians. Those interested in a career as a technician should have an aptitude for mathematics and science, and enjoy technical work. An ability to do detailed work with a high degree of accuracy is necessary; for design work, creative talent also is desirable. Employment opportunities are expected to be favorable through the mid- 1980's.

S. Air-Conditioning, Refrigeration, and Heating Mechanics. Increases in household formations and rising personal incomes should result in a very rapid increase in the number of air conditioned homes. Air-conditioning in offices, stores, hospitals, schools, and other buildings also is expected to increase. Employers prefer high school graduates who have had courses in mathematics, physics, and blueprint reading. Mechanical aptitude and an interest in electricity are important qualifications. Good physical condition helps in lifting and moving heavy equipment. Employment is expected to increase very rapidly through the mid- 1980's.

6. Draftsmen. Those planning careers in drafting should: be able to do detailed work requiring a high degree of accuracy; have good eyesight and eye -hand coordination because most of their work is done at the drawing board; be able to function as part of a team since they work directly with engineers, architects, and skilled workers; and be able to do free -hand drawings of three dimensional objects. Employment of draftsmen is expected to rise rapidly as a result of the in- creasingly complex design problems of modern products and processes. Prospects will be best for those having post-high school drafting training.

'Bureau ¿Labor Statistics, Occupational Outlook Handbook, 1974 -75 edition.

www.americanradiohistory.com If you're looking for a new career, you should keep in mind that some job fields will grow faster than others over the next ten years. (Some, such as barbers, railroad workers, meat - cutters, etc., will actually decline.) THE 70s &80's Why do we tell you this? We're ICS - International Correspondence Schools -and we offer career training in fields the government experts say are likely to increase over the next decade.

INCREASE IN JOB OPPORTUNITIES, 1972 -85

96.3%

48.9

30% 31% 18.4% 111 Engineering IAuto Air Con- Elcc- Accoun- Drafts- & Sci.Tech. * Mechanics ditioning tricians tants men

', 111

ICSInternational Correspondence Schools, Scranton, Pa. 18515

Please mail me the Free Career Booklet and Free Demonstration Lesson for the field I have checked below. I understand I am under no obligation.

Electrician Air Conditioning & Refrig. ICS Center for Degree Studies Engineering Automotive Mechanics Associate in Specialized Business Accounting Business Management ee in: Drafting Airline Travel ccountin Business Mgt. Electronics Technician Interior Decorating Associate in Specialized Technology TV Service & Repair Income Tax Degree in: Surveying& Mapping Motel/Restaurant Management Civil Eng. Electrical Eng. Construction Electrician Appliance Servicing & Repair Mechanical Eng: Chemical Eng. Diesel Mechanics High School Electronics Mechanical Design

Print Name Age

Address City

State Zip Telephone Veterane Taken for career purposes. ICS Programs qualify for VA Benefits. XA104H Canadian residents use Scranton, Pa. address for service from ICS Canadian, Ltd. In Hawaii: 931 University Ave., Honolulu. Hawaii 96814. www.americanradiohistory.com September /October 1977 THE STAFF elementary Volume 17, No. 5 Editor -in -Chief and Electronics Group Coordinator Julian S. Martin, WA2CQL Managing Editor Alan H. Rose, K2RHK Communications Editor Neil Shapiro, WB2KQI, KAFA7222 Editor Audio lectronicsElectronics Digest' Christine Begole, KFC3553 Dedicated to America's Electronics Hobbyists -Including Citizens Band Editor Kathi Martin, KGK3916 SPECIAL HOME COMPUTER ISSUE into one of the new Workbench Editor * 41 Computers Phone the Future -you can link your home Hank Scott computerized nerve centers 46 e/e previews the -Heath Home Computer Systems Art Director * HP -65, one of the 61 Computer Readout-Norm Meyers looks at the Hewlett- Packard Ralph Rubino * first programmable calculators on the latest in Assistant Art Director 64 Computer New Products -e /e continues to keep you up to date Augustus Ginnochio home and hobby computer technology the -SWTP 6800 Microcomputer kit Cover Art Director 75 e/e assembles Irving Bernstein ONE -OF -A -KIND CONSTRUCTION PROJECT roulette wheel Art Assistants 49 Las Vegas LED -build a new career with your own electronic Modero Robert EQUIPMENT FOR YOU TO BUILD Caroline Imparato MORE AND BETTER 58 Flashmate -keeps your camera out of the dark electronically Joni Erlon * with * 87 Super Soother -SCA adapter lets you enjoy the long autumn afternoons Advertising Director continuous music good David J. Miller, KCX1268 91 LEDIT -keeps your Silicon Controlled Rectifiers and Diodes looking Advertising /Research Associate CITIZENS BAND UPDATE Jyll Holzman, KAKZ1490 through the 'r 53 CB XCVR Checkout -four more of the newest 40- channel rigs are put Production Director mill by the e/e lab Carl Bartee 67 CB New Products -keep your signal crisp and clear with these new accessories 92 Production Manager 68 Kathi's CB Carousel -our new TV star checks out the E. F. Johnson Messenger Carole Dixon hand -held /e brings together the best of the power mikes, Production Manager 71 Loud and Clear, Good Buddy! -e Assistant them Mary Carfagno and shows how to use Circulation DX IN HI -FI AND UNDER COVER Newsstand stations Director 21 DX Central -Don Jensen lifts the wraps on some of the secret shortwave Don Gabree 81 Hi -Fi DX -your FM can pull in DX too, and clearly Subscription Circulation & UP -TO- THE -MINUTE ITEMS Marketing Director 48 Master Truckers Learn on Mini- Trucks -remote control trucks sharpen drivers' skill Robert V. Enlow 70 Camera Fights Tooth Decay-ultra - violet electronics save you a lot of trouble Subscription Circulation Manager 80 Aerogenerator -your electricity troubles are gone with the wind Eugene S. Slawson 90 Not According to Hoyle- computers and LEDs give Bridge a new twist Director of Market Development OUR REGULAR DEPARTMENTS consumer items from the electronics manufacturers James C. Weakley 6 Hey, Look Me Over -newest 16 Bookmark -by Bookworm 30 Newscan -what's going on in electronics Knows answers keep on coming Publisher 34 Ask Hank, He -his President and Antique Radio Corner-Jim Fred shows you how to replace those old tubes with Joel Davis 78 new, and keep the same sockets received Vice President and * 93 Basic Course -how TV signals are transmitted and General Manager 98 Literature Library Cover Stories Leonard F. Pinto Vice President and Treasurer Victor C. Stabile, KBP0681

ELEMENTARY ELECTRONICS Is published bimonthly by Davis Publica- tions, Inc. Editorial and Executive C"'' z offices: 229 Park Ave. So., New York, NY 10003; all subscription orders and mail regarding subscriptions should be sent to P.O. Box 2630, Greenwich, CT 06830. One -year subscription (six Is- sues)- $6.50; two -year subscription (12 issues) -$13.00; three -year subscrip- AUTHORS IN THIS ISSUE four -year tion (18 issues) -$19.00; and Fred, subscription (24 issues) -$25.00. Add David R. Corbin, James 67 cents postage for each year for U.S. Herb Friedman, Lawrence Fried- possessions and Canada; $1.34 each man, Frank I. Gilpin, Harry L. year, all other countries. For change Don of address, please advise 4 to 6 weeks Helms, Jr., Jorma Hyypia, before moving. Send us your current Jensen, Kathi Martin, Norman mailing label with new address. Adver- Meyers, Hank Scott, Walter Si- tising offices: New York, 229 Park Avenue South, 212- 673 -1300; Chicago, koniwiz, and the ELEMENTARY 520 N. Michigan Ave., 312 -527 -0330; E LECTRONICS Editorial Staff. Los Angeles; J. E. Publishers' Rep. Co., 8732 Sunset Blvd., 213- 659 -3810, Second -class postage paid at New York, NY and at additional mailing office. Copyright 1977 by Davis Publications, Inc. 4 ELEMENTARY ELECTRONICS /September- October 1977

www.americanradiohistory.com Reg. U. S. BUILD 20 RADIO Pat. Off, and Electronics Circuits PROGRESSIVE HOME RADIO -T.V. COURSE

Now Includes * 12 RECEIVERS * No Knowledge of Radio Necessary 3 TRANSMITTERS * No Additional * SQ. WAVE GENERATOR * Parts or Tools Needed * SIGNAL TRACER * Solid State Circuits * AMPLIFIER Training Electronics Technicians Since 1946 * SIGNAL INJECTOR * Vacuum Tube Circuits CODE OSCILLATOR FREE EXTRAS YOU DON'T HAVE TO SPEND SET OF TOOLS OF DOLLARS HUNDREDS FOR A RADIO COURSE SOLDERING IRON The "Edu -Kit" offers you an outstanding PRACTICAL HOME RADIO COURSE at a ELECTRONICS TESTER rock -bottom price. Our Kit is designed to train Radio & Electronics Technicians, making PLIERS -CUTTERS use of the most modern methods of home training. You will learn radio theory, construc- VALUABLE tion practice and servicing. THIS IS A COMPLETE RADIO COURSE IN EVERY DETAIL. DISCOUNT CARD You will learn how to build radios, using regular schematics; how to wire and solder, CERTIFICATE OF MERIT In a professional manner; how to service radios. You will work with the standard type of TESTER INSTRUCTION MANUAL punched metal chassis as well as the latest development of Printed Circuit chassis. HIGH FIDELITY GUIDE QUIZZES You will learn the basic principles of radio. You will construct, study and work with TELEVISION BOOK RADIO RF and AF amplifiers and oscillators. detectors, rectifiers, test equipment. You will learn TROUBLE -SHOOTING BOOK and practice code, using the Progressive Code Oscillator. You will learn and practice MEMBERSHIP IN RADIO -TV CLUB: trouble -shooting. using the Progressive Signal Tracer, Progressive Signal Injector. Pro- CONSULTATION SERVICE FCC gressive Dynamic Radio & Electronics Tester, Square Wave Generator and the accompany- AMATEUR LICENSE TRAINING mg instructional material. PRINTED CIRCUITRY You will receive training for the Novice, Technician and General Classes of F.C.C. Radio Amateur Licenses. You will build Receiver, Transmitter, Square Wave Generator, Code Oscillator, Signal Tracer and Signal Injector circuits, and learn how to operate them. You will receive an excellent background for television, Hi -Fi and Electronics. Absolutely no previous knowledge of radio or science is required. The "Edu -Kit" is SERVICING LESSONS I the product of many years of teaching and engineering experience. The "Edu -Kit" will I provide you with a basic education in Electronics and Radio, worth many times the low You will learn troubleshooting and price you pay. The Signal Tracer alone is worth more than the price of the kit. Servicing in a progressive manner. You will practice repairs on the sets that you construct. You will learn symptoms THE KIT FOR EVERYONE and causes of trouble in home. portable and car radios. You will learn how to You do not need the slightest background ages and backgrounds have successfully use the professional Signal Tracer. the In radio or science. Whether you are inter- used the "Edu -Kit" in more than 79 coun- unique Signal Injector and the dynamic ested in Radio & Electronics because you tries of the world. The "Edu -Kit" has been Radio & Electronics Tester. While you want an interesting hobby, a well paying carefully designed, step by step, so that are learning in this practical way, You business or a job wîtb a future, you Will find you cannot make a mistake. The "Etlu -Kit' will be able to do many a repair lob for the "Edu -Kit" a worth -while investment. allows you to teach yourself at your own your friends and neighbors. and charge Many thousands of individuals of all rate. No instructor is necessary. fees which will far exceed the price of the "Edu- Nit." Our Consultation Service will help you with any technical prob- PROGRESSIVE TEACHING METHOD lems you may have. The Progressive Radio "Edu -Kit" is the foremost educational radio kit in the world. and is universally accepted as the standard in the field of electronics training. The "Edu. Kit" uses the modern educational principle of 'Learn by Doing." Therefore you construct. FROM OUR MAIL BAG learn schematics, study theory, practice trouble shooting -all in a Closely integrated program designed to provide an easily -learned, thorough and interesting background in radio. J. Stataitis, of 25 Poplar Pl.. Water- You begin by examining the various radio parts of the "Etlu- Kit." You then learn the bury. Conn., writes: "I have repaired function, theory and wiring of these parts. Then you build a simple radio. With this first several sets for my friends, and made set you will enjoy listening to regular broadcast stations, learn theory. practice testing money. The "Edu -Kit" paid for itself. I and troubleshooting. Then you build a more advanced radio, learn more advanced theory was ready to spend $240 for a Course. and techniques. Gradually, in a progressive manner, and at your own rate. you will but I found your ad and sent for your find yourself constructing more advanced multi -tube radio Circuits, and doing work like a Kit." professional Radio Technician. Ben Valerio, P. 0. Box 21, Magna. Included in the "Edu -Kit" course are Receiver, Transmitter, Code Oscillator, Signal Utah: "The Edu -Kits are wonderful. Here Tracer, Square Wave Generator and Signal Injector Circuits. These are not unprofessional I am sending you the questions and also "breadboard" experiments, but genuine radio circuits, constructed by means of professional the answers for them. I have been in wiring and soldering on metal chassis, plus the new method of radio construction known Radio for the last seven years. but like as "Printed ircuitr These circuits operate on our re. ular AC or DC house current. to work with Radio Kits, and like to build Radio Testing Equipment. I en- joyed every minute I worked with the THE "EDU -KIT" IS COMPLETE different kits; the Signal Tracer works fine. Also like to let you know that I You will receive all parts and instructions necessary to build twenty different radio and electronics cir- feel proud of becoming a member of your cuits, each guaranteed to overate. Our Kits contain tubes. tube sockets, variable, electrolytic, mica, ceramic Radio -TV Club." and paper dielectric condensers, resistors. tie strips, hardware, tubing, punched metal chassis, Instruction Robert L. Shuff, 1554 Monroe Ave., Manuals, hook -up wire, solder, selenium rectifiers, coils, volume controls. switches, solid state devices, etc. Huntington, W. Va.: 'thought I would drop you a few lines to say that I re- In addition, you receive Printed Circuit materials, including Printed Circuit chassis. ceived my Edu -Kit, and was really amazed special tube sockets, hardware and instructions. You also receive a useful set of tools, a that such a bargain Can be had at such professional electric soldering iron, and a self -powered Dynamic Radio and Electronics a low price. I have already started re- Tester. The "Edu -Kit" also includes Code Instructions and the Progressive Code Oscillator, pairing radios and phonographs. My in addition to F.C.C. Radio Amateur License training. You will also receive lessons for friends were really surprised to see me servicing with the Progressive Sigm.l Tracer and the Progressive Signal Injector, a High get into the Swing of it so quickly. The Fidelity Guide and a Quiz Book. You receive Membership in Radio-TV Club, Free Consulta. Trouble -shooting Tester that comes with Pion Service, Certificate of Merit and Discount Privileges. You receive all parts, tools. the Kit is really swell. and finds the instructions. etc. Everythino is yours to keep. trouble, if there is any to be found.'

Progressive "Edu- Kits" Inc., 1189 Broadway, Dept.: Sb Di Hewlett, N.Y. 11557 PRINTED CIRCUITRY I Please rush me free literature describing the Progressive At no increase in price, the "Edu -I(i "r now includes Printed Circuitry. You build I Radio -TV Course with Edu -Kits. No Salesman will call. a Printed Circuit Signal Injector, a unique servicing instrument that can detect many Radio and TV troubles. This revolutionary new technique of radio construction is now NAME becoming popular in commercial radio and TV sets. A Printed Cirituit is a special insulated I ADDRESS chassis on which has been deposited a conducting material which takes the place of I wiring. The various parts are merely plugged I CITY & STATE ZIP. in and soldered to terminals. Printed Circuitry is the basis of modern Automation Electronics. A knowledge of this PROGRESSIVE "EDU- KITS" INC. subject is a necessity today for anyone interested in Electronics. 1189 Broadway, Dept. 5 8 6 DJ Hewlett, N.Y. 11557

CIRCLE 15 ON READER SERVICE COUPON

www.americanradiohistory.com vides complete electroplating capability and can be used in total safety. Unlike conventional methods that require a series of expensive and toxic plating baths, the Ranco EP -1 uses patented Hey, felt-tip pens. Advantages of the Ranco EP -1 system include: complete porta- bility, no special skills required, total look me over plating capability, non -polluting, completely non -toxic, no baths or solutions, Showcase of New Products disposable plating pens for 10 different metals, and low cost. Completely contained in its own case, the EP -1 allows Electroplating System anyone to produce professional quality A new, low -cost portable electroplating electroplating the very first time. The system, specifically designed for plating Ranco EP -1 Portable Electroplating Sys- craft and hobby projects, has been in- tem is available at $410. Non -toxic, dis- troduced by Micro Materials. Designated posable plating pens are available in 24K silver, nickel, chrome -color, rhodi- the Ranco EP -1, the advanced unit pro- gold, CIRCLE 62 ON READER SERVICE COUPON um, black nickel, copper, tin, and zinc. A pure chromium pen is available on special order only, since it contains toxic chromic acid. Each pen will produce more than 10 square feet of electroplating. Additional pens are currently under development. For more information, write to Micro Materials Corpora- tion, 100 Grand Street, Westbury, NY 11590.

Two in One for Lab The Logiklab Model 151 by Integral Elec- tronics features the innovative combination of a digital signal source together with a logic power supply. The supply is highly regulated, short- circuit proof and capable of delivering 1 A at 5 VDC. The signal source, in the Astable Mode, simultaneously provides true and com- plementary TTL compatible square waves and pulses over the frequency range from 10 Hz to 100 KHz. Manual and remote

sound and safe CIRCLE 58 ON READER SERVICE COUPON gating of the oscillator is available. In the Monostable Mode, single pulses, con- imailmi CB Hump Mount Speaker. tinuously variable from 5 microseconds Eliminates CB installation prob- hassle. Acoustically designed to 50 millseconds are produced, either lems. Any transceiver mounts on speaker deadens static and chan- by manual or remote trigger. Fail -safe the Kamel speaker, speaker nel noise, eliminates voice distor- design procedures and full power burn -in mounts on the hump, fits snugly tion. We make having an expen- guarantee a highly reliable and versatile when driving. CB dials easy to see, sive CB rig in your vehicle safe and instrument at a moderate unit price of easy to reach. For safer operation. worthwhile. Isn't it about time $79.50. For further information, write to To remove, just unplug antenna somebody did? Integral Electronics Corp., P.O. Box 286, and power leads, lift entire unit and Commack, NY 11725. place in trunk for maximum sec- KIfket ' urity. No screws' to unscrew. No Budget Speaker The SSU -1050 is Sony's new budget as /Klnket. priced speaker delivering clean, low -dis- Acoustic Fiber Sound Systems, Inc. tortion sound over a wide frequency Indianapolis, Indiana range. The two-way acoustic suspension All afse /KRIKET® products are manufactured In the U.S.A. design features an 8 -in. woofer and 21/4- Inc. Copyright 1977, Acoustic Fiber Sound Systems, in. tweeter positioned in high- density, CIRCLE 5 ON READER SERVICE COUPON thick chipboard enclosure which is sealed and lined with fiberglass to prevent unwanted vibration and resonance. Ampli- fiers supplying between 10 and 50 watts

6 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com NEW WIDE FIELD TELESCOPE Enjoy clearest, brightest, most spectacular wide - SAVE 50% angle views of stars, 8 x 20 MONOCULAR moon, comets with our Top -quality Spy Scope, a unique, easy -to -use, port- $30 value, now $14.95! able 43/4"; f/4 Newtonian Special purchase saves reflector. Top quality op- you 50 %. 100% coated tics provide fine resolu- $149.95 optics; 393 ft. field of tion. Only 17 ", 10 lbs.! view. Only 2 oz.- stores Ppd. No. 2001 in pocket, purse, glove box. $14.95

SAVE 50%- DELUXE AM /FM WALL RADIO Great surplus buy saves you 50% on brand new re AM /FM Deluxe Wall Radio w/ handsome silver/ black control panel. Mount anywhere den, kitchen, bedroom, office, workshop. Self -cont. Philco-Ford radio chassis (143/4 x 313Ae x 31/2") w111 transis- PRO ELECTRONIC SOUND CATCHER tors, vol. control, AM /FM hi- sensitivity tuner, AFC Parabolic mike w/ 183/4" transparent 23/4" dia. speaker, 71/2" 110V AC cord. Orig. cost reflecting shield & 2 I.C.'s in amplifier $30 ea. in 3000 quant. for natl. motel chain. Re- magnifies signals 100X over omni- tail value over $40! Buy several now. direction mikes. Catch sounds never before heard; highest signal to noise No. 72,275 (READY TO PLAY!) .. Ppd. ratio poss. 51/2 lb. $19.95 No. 1649 (REQ. SAVE! buy 3 or more @$17.95 EA. 29V BATT.) ...

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www.americanradiohistory.com of power are recommended to drive the been the need for manual tuning, a dif- HEY, LOOK ME OVER SSU -1050. Nominal impedance is 8 ficulty that is completely eliminated in ohms. The unit's frequency response Surveyor's new Model 10P, three -band, measures from 50 Hz to 20 kHz with a VHF hi /lo UHF scanner. The Surveyor crossover frequency at 1 kHz. Designed l0P Scanner, in addition to its numerous to be placed vertically or horizontally, the other featuers, has two facilities with unit features removable grilles. The units great appeal to SW listeners. The 10P are finished in Summertime Teak vinyl, has a top level programmable switch, weighs 18 lbs. and sells for $130.00 a letting the listeners program easily and CIRCLE 54 ON Get all the facts direct from your quickly to any and all bands. There is READER SERVICE pair. write to Sony also a priority switch that is the listener's COUPON local Sony audio dealer or Corp. of America, 9 West 57th St., New assurance of hearing transmission on York, NY 10019. CIRCLE 63 ON Programmable Scanner READER SERVICE COUPON As a hobby, shortwave listening has kept pace with the boom in CB. One of the problems of the SWL in the past has

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100 %ó state, dc power cord Take it with you anywhere. The SSR -1 is a complete fine ssb cw tuning solid dc operation from auto or general coverage SW receiver with operation from available for external 12V telescoping antenna, provision for 500 kHz to 30 MHz. Compare these features: Built- boat Built -in -in speaker Drake HS -1 in ac power supply and provision for internal D" external antenna Built CIRCLE 56 ON READER SERVICE COUPON impedance- matched headphones now cell batteries in built -in battery holder Synthesized cushioned, in an 8 -track 13' wide, 11" deep, 5.5" high longer interests you, slip circuitry means no range crystals to buy Dial cali- available Small size of 14 cm) Weight 14 lbs. (6.4 kg). stereo tape or switch to a local AM or bration within 5 kHz at all frequencies Product (33 x 28 x The BM -1126 has detector for ssb /cw reception Clarifier for extra FM station. versatile a multitude of unique features including send name and date of this publication to To receive a FREE Drake Full Line Catalog, please pushbutton eject, a cartridge compart-

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Mry we send you your choice of these 3 practica 111111(11111111fs11ti111111111111111l1111111111 time- and -money -saving books as part of an un- Facts About Club Membership usual offer of a Trial Membership in Electronics ELECTRONICS BOOK CLUB Book Club? The 3 introductory books of your choice carry publishers retail prices of up to S51 75 They are yours for only 99e P.O. Sox 10 Here are quality hardbound volumes. each each (plus pottage and handling) with your Trial Mem Blue Ridge Summit, Pa. 17214 especially designed to help you increase your tership know -how. earning power. and enjoyment of elec- You will receive the Club News. describing the current Please open my Trial Membership in ELECTRONICS tronics. Whatever your interest in electronics. Selection Alternates and other offerings. every 4 weeks (13 times a year) BOOK ,CLUB the 3 I you'll find Electronics Book Club and send me books circled below offers practical. If you want the Selection. do nothing it will be sent to you understand the cost of the books I have selected is only quality books that you can put to immediate use automatically B you do not wish to receive the Selection, or d 99c each, plus a small shipping charge. It not de- and benefit. you want to order ore o) the many Alternates offered. you lighted. I may return the books within 10 This extraordinary offer is intended to prove to simply give instructions on the reply form (anc in the en- days and owe velope) provided. and return d to us the you. by date specified nothing. and have my Trial Membership cancelled. I through your own experience. that these very This date allows you at least 10 days in which to return the agree io purchase at least four additional books during real advantages can be yours...that it is possible to torm h. because of late mail delivery, you do not have 10 the nert 12 months. after which I may cancel my mem- keep up with the literature published in your areas days to make a decision and so receive an unwanted Selec non, return bership at time of interest. and to save substantially while so do- you may t at Club expense any Personal service tor your account -nn computers used, ing. As part of your Trial Membership. you need To complete your Trial Membership. you need buy only 101 563B36 510 628 582 743 purchase as few as four books during the coming 12 lour additional monthly selections or alternates during the 780 790 754 785 800 841 -months. You would probably buy at least this many next 12 months. You may cancel your Membership any time 861 905 909 anyway...without the substantial savings offered atter you purchase these four books. 913 919 1010 through Club Membership. All books -including the Introductory Offer-are fully re- turnable after 10 days if you're not completely satisfied To start your Membership on these attractive All books are offered at low Member prices. plus a small Name Phone terms. simply fill out and mail the coupon today. postage and handling charge Prepaid orders shipped You will receive the 3 books of your choice fin- postpaid 10-day inspection. YOU NEED SEND NO MONEY: Continuing Bonus If you continue atter this Trial Mem- Fddrexs bership, you will earn a Dividend for 1f you are not Certd+cate every book delighted. return the books within 10 you purchase Three Certificates payment days and plus of the City your Trial Membership will be cancelled nommal sum of $1 99. will entitle you to a valuable Book without cost or obligation. Dividend of your choice which you may choose from a list provided Members State Zip ELECTRONICS BOOK CLUB, P.O. Bon 10. Blue Ridge Summit. Pa 17214 (am onor valid for new Members only Foreign and Canada add 10 °0 EE -97

www.americanradiohistory.com and the warning sequence is repeated. HEY, LOOK ME OVER During normal conditions, the unit picks up the weather station's continuous re- For more information, write to Boman port. Operates within 40 to 50 miles of Industries, 9300 Ha -1 Road, Downey, a transmitter. Optional Antenna Kit ex- AC- powered, CA 90241. tends range up to 80 miles. with battery back -up feature. Should an Siren -Equipped Weather Radio electrical failure result from a weather Weatheralert offers 24 -hour protection emergency, unit automatically becomes against loss of life and property from powered by an internal 30 -hour battery. tornados, severe thunderstorms and Sells for $39.95. Write or phone Weather - other weather emergencies. The receiver alert Co., 639 South Dearborn Street, sounds a siren -triggered by a signal Chicago, IL 60605. Enclose $2.50 addi- from the local U.S. Weather Service tional for shipping and handling. Transmitter -whenever dangerous condi- At Right Angles 64 ON READER SERVICE COUPON tions threaten. A complete report on the CIRCLE like as an equivalent to emergency is broadcast directly after, Here's a new product that looks Connector performs someone read the blueprints with double the cube tap. Intra- Connector is available vision when the product was made. No in the five most popular flat ribbon matter, the final product is a great aid to cable line widths to work immediately people using flat ribbon cables and with the bulk of all of today's systems: standard double -row socket connectors. 20, 26, 34, 40 and 50 contacts (lines) Called, the lntra-Connector, it consists wide. Intra- Connector is available from of a standard female double row socket A P Products distributors, who can be connector and two sets of mating male located through the company's toll -free contact pins, at right angles to each Faster And Easier Line, (800) 321 -9668. other. Thus, Intra- Connector can be used Prices range from $6.00 to $10.50. Write as a through -line connector, either A P Products, Box 110, 72 Corwin Drive, straight or at right angles, with a re- Painesville, OH 44077. dundant set of male pins to facilitate Hole Cutting Kit signal tracing and measurement at various points throughout flat cable sys- Drill burr -free holes for easy mobile CB tems- wherever, in fact, a connector is antenna installation or for electrical and now installed. In this application, Intra- hobby uses with the unique Conecut Kit con- Connector is a valuable testing tool. from GC Electronics. The kit (3420) Intra- Connector can also be used to ex- tains two drill bits (No. 1 drills holes pand upon existing systems by residing from 1/4-in. to 13 /16 -in; No. 2 from 5/8 -in. as a line "tap," the full cable wide. Thus to 1- 3 /16 -in.), cutting compound and as- daisy chains can be built into existing sortment of fiber hole gauges, all in a COUPON CIRCLE 51 ON READER SERVICE systems quickly and easily. Here, Intra- convenient vinyl pouch. Holes can be

C Solderless strips, backing board and binding Pick an ACE for Faster and posts. Everything you Send for our complete A P catalog, and test your Easier solderless circuit need to build testing. The Faster and Easier Book. own circuit. Used to be you'd building and Price get a circuit idea, lay out a pc board, ACE Tie DIP No. No. Board Size Part (inches) Each it, together, No. Model No. Points Capacity Buses. Posts print solder everything 4- 9/16 :5.9/16 $18.95 923333 200 -K (kit) 728 8 (16's) 2 2 change your layout, 8 2 4- 9/16x5 -9/16 28.95 troubleshoot, 923332 208 ( assem.) 872 8 (16's) 1032 12 (14's) 2 2 4- 9/16x7 24.95 try a new board, and spend abso- 923334 201 -K (kit) 34.95 212 (assem.) 1224 12 (14's) 8 2 4- 9/16x7 923331 - 46.95 lutely too much time breadboarding. 1760 18 (14's) 10 2 6- 1/2x7.1/8 923326 218 (assern.) 59.95 2712 27 (14's) 28 4 8x9-1/4 Now A P ACE All Circuit Evaluators 923325 227 ( assem.) 79.95 36 (14's) 36 4 10- 1/4x9 -1/4 let you breadboard in a fraction of 923324 236 ( assem.) 3648 the time. Make your changes immediately. Keep full leads on your Order from your A P components. Avoid the heat damage distributor today. Our A P PRODUCTS possible with repeated soldering distributor list is growing INCORPORATED and de- soldering. A P made the first daily. For the name of the Box 110 72 Corwin Drive modern solderless breadboard, and distributor nearest you call Painesville, Ohio 44077 we still make them best. Toll -Free 800- 321 -9668. 216/354 -2101 TWX: 810-425-2250

CIRCLE 6 ON READER SERVICE COUPON ELEMENTARY ELECTRONICS /September- October 1977 10 www.americanradiohistory.com Introducing the mobile that can move And like all Cobras it comes equipped you out of the world of the ordinary with such standard features as an easy - and into the world of the serious CB'er. to -read LED channel indicator. The Cobra 138XLR Single Sideband. Switchable noise blanking and limiting. Sidebanding puts An RF /signal strength meter. And you in your own Cobra's exclusive DynaMike gain control. private world. A You'll find the 138XLR SSB wherever world where there's Cobras are sold. Which is almost every- less congestion. where. Because Cobra's got a nationwide More privacy. network of dealers and Authorized More time to talk. Service Centers offering sales, installation, It's all possible because instead of 40 service and advice. So come on in. channels you get your choice of 120 And move on up. channels. Both AM and SSB. And , , .. instead of 4 watts of legal power you - ,.,, get 12 watts of legal power. So you get ® almost double the range of AM. ob/-r With the 138XLR Single Sideband Punches through loud and clear. there's less background noise and less Cobra Communications Products interference. So there's cleaner, clearer DYNASCAN CORPORATION reception. Because like all Cobras, the 6460 W Cortland St., Chicago, Illinois 60635 Write for color brochure 138XLR SSB is engineered to punch EXPORTERS: Empire Pleenvtew. N Y CANADA. Atlas Electronics Toronto through loud and clear. Even in crowded CIRCLE B ON READER SERVICE COUPON metropolitan areas. 11111) LIZY.

www.americanradiohistory.com drilled in almost any thin material with HEY, LOOK ME OVER the Conecut drill bits -steel, sheet metal, tubing, conduit, plastic or formica. Pilot holes or center punch marks are unnecessary, even on curved surfaces. Sells for $34.95. For more information, write to GC Electronics, 400 South Wyman, Rockford, IL 61101. Amateur Desk Clock The QTR -24 Yaesu World Clock is one of the newest additions to the Yaesu line of CIRCLE 68 ON READER SERVICE amateur equipment. It is a 12- hour /24- hour clock which indicates the daylight/ COUPON dark hours around the world. The clock $30.00. For more information, write to is run by a single size C drycell which Yaesu Musen USA, Inc., 7625 East Rose - will last a year. It is 53/4 -in. in diameter crans Ave., Unit #29, Paramount, CA x 21/2-in. deep, and sits on the desk or 90723. CIRCLE 65 ON READER SERVICE COUPON it can be mounted on the wall. Price is 30 MHz Portable Frequency Counter P.O. Box 4430A Santa Clara, CA 95054 MHz (408) 988-1640 30 portable frequency counter by Same day shipment. Fest line parts only. Factory B &K- Precision is not much larger than a tested. Guaranteed money back. Quality IC's and pocket calculator. The new Model 1827 other components at factory prices. offers full six -digit LED display and oper- INTEGRATED CIRCUITS 1B 0408 ation to 30 MHz. The B &K- Precision B OTEL 74L530N 39 LW, 50 5Ú40r0 .. . 74006 1) ]4LS)dN 46 LM3)9 1827 features 1 ppm resolution on a 74026 1 LS%SN 65 1613006 ELECTRONICS !4046 )4LS90N 10 IM301 23 á9691N 1 1U LM382 six -digit scale with ±.25 ppm stability. '4059599 1 09 1.1.12036 3 90 SPECIAL P000UCTS

74196 63 4 1.510'6 52 1.61)09H 4 00 RE5151065 65 Slupxalcn Irma, 9 OU )4156.26 St L617245 500 .a",.P The input circuitry is sensitive enough )42326 1 39 741.51.36 52 0M%3399 995 ns0 per ,o. r SVdlerms Mom Pu 3547304 50 76 9M)4ICM 2m p4, azs 3 D m9 M4M l is ñ p 4 ] to display a 100 mV sinewave signal, M426 18 4 Sí366 9 961]4i6 5 50 c ryeea 9 íi r n 85 1 IOBO Nwó '4456 4151516 6 4617476 KEYBOARDS olperalz goopiLV. to s 50 94061556 .d6113 5L1ó 05 but is protected against an input signal 74486 »L5151N 17991 %.° 5.165 enroder CLOCK MODULES 74606 333 1. 9 55 Cumplele alarm Rooks rea, Sit63x 27 ][140)5 of up to 200 volts (peak AC & DC). An Teal kook 5,97 2 CA 04026 3 d 6' ..5nA. 0 wt 7 optional signal tap allows the 1827 to sé ó4óz a Si 35Ae, dnrea3M e `adB4á;t. )s .A,13,,3:'33 Comm B043 II 50 6161002A C or f 59 8 95 1 50 60403 0 . D wm4oÁ41w113 44 2 3 Tran,rNrmer 2 25 continually monitor the output frequency e 50 c500i t10 I 10A C E 37006a 2aÁ Ix aud e EMMfa1Ma,.3. or 75 C09040 i j,5 102. Iran 25 59 .94042 , IC of a 23- or 40- channel CB transceiver 'd 34 m44 z9 Specol 55 69.41 J 00 pme.r nuS5n Lw rnrt°'.°4,,v Switche, when 2p 5 1 P Mw 10 JumOo ém : 95 without affecting normal set operation. sú Ora 25 óia 18 LEO MaVMIMMP. 25 Pr 56 s CIPIN3 95 20 ambe, preen, yarrow The 1827 is designed to provide fully N15p 16 ' DISPLAY LEOS NE 55N 61ANI CA 2'3 2 90 Bi23 5 CRYSTALS 625569 05 MHz 450 20100MM1 3 50 MAN, 00 4 50 09)652 MNr ] IS CA 3W 1 W CIRCLE 66 ON 1 t5 E565A CÚ4069 5 3 MHT ICaOPROCESSOR C 1 1 05 a 5 2 a520 MMa 2 50 3W W Co4069 16 3 81'26 5 BUBOwrt Á data I 25 SERVICE N -5 CO40,0 5 MNe a 25 ] 2P08 Lou 50 READER ari 2B 215 e n a W 90 50088MM3 50 ULIO)R CA 00 1 00 6045,r J45 450 425 3 `A 1 »N I 19 )91.05 9I1 CO30_, d 00 9MIU 390 $1BSMMa u 500 90 COUPON 4198 45 021C w jo + i 90 ,1756 39C,05 1 0U CO.:' MW 390 51M3MIN 450 01.)g I 36 a5o 741906 695 T 65006MN( 450 .747 M10 1 25 ) C04f" 05A,EMOaYaAMB22 e50 32 IOU 4192N 2308 Mt 49000 B 33. M6a 4 1C NU359 CC 353 70 50 P 50 rNU CC 500 90 .41 N5 i 35 39 76392MMe%w ]2rBdMna +. ;r61. 233 4 0251 1195 5452LN 39 CoB2040B1 35)95MNe1iU rN 510 CA 500 0 rr143130000 LC ROO _ 30 9BN 1 3, 0 04 50 iRAMSPORMERf 0000 JP10u2C5 24 F60901 909 220 ,5'S4CN 10 gpll ma vamlormet r 1i 3M12i12 nan6 f U C P U2LI 30 00 3W 058 nrmnsuul 1 15 %N910N ti L04490 U500 26V5LTWOw 825 55 UARlúlw 06, fluorescent I zo % 9266 p45W 43204 1±5 TS 12V20n wall plug 99 r5'013 ..¡Ur 5 dim, :34UN ' 55 2;494011 L04506 12V CT 250 nia wal plug 3 sr 2,1980. I I 90 1341 6 NSÑ33M 3rg- M18dn 39 A le O CORVERIER MM5392 5o COMPUTER BOARD KITS M3a06 tl 604515 MIOM 66X699 digit pisplay w 20 55 tt RAM Bpdrd xn 225 00 60 CO3515 I 01p 520 Claire. pbotpeells 50 1MHOx11 B700LN J200 p5330 a EPROM NU 114 50 34 L0a51- 50 4,05N LM 3x.15 B)50 ,3 95 04i10-3 400 k.',12. 00 r:0ewnlxN U 123'tMe, gm dMl M ;41.5006 28 1.MJ40tl 24 ' COa518 i23 0130 25 PO. IL 4 3W 4 5 de0'ardwcaennnn0r'2550 900 5 50 N925'26 V to F a0 42UOZ 1900 i 9a00 r enwa I. UVclóMtc i0 liguio xAe30w 41.5í3N 61 .1.613401 B 70 800 5xrFgOM board a4xl 8500 41.5146 1 30 t .7915139 ` 'SN Slanc RAM board nd 495 00 2924 50 406206 28 M34ñ4 .5 I .0 COÚII I ALOC6S TV GAME CHIPS Id 290 14010031a .16900 No 0 .. :.. 290 ..,

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Digital Thermometer $65.00 2.5 MHz Frequency Counter Kit Home Alarm Kit $18.75 General purpose or medical 32 - 230 °F. As low as 10 Hz 6 -.50" digits with PC Designed for use with electronic siren Disposable probe cover .2 accuracy. board and full instructions. $40.00 module. AC power, battery backup, entry Completely assembled w compact case. exit delay. Instant alarm for night use autoranging operation, or can be NO /NC circuits. Test and arm indicators switched to a 1 second position for 1 Hz Function Module Card Kit 2 amp switching capability. All parts with Not a Cheap Clock Kit $17.45 frequency counter into 3'oo Converts any complete instructions minus power sup- resolution -even while measuring CB Includes everything except case. 2 -PC digit DVM. digital thermometer, pulse ply. Electronic siren module kit. $2.75 radio boards. 6 -.50 LED Displays. 5314 clock S square generator from 10 Hz to 100 kHz. frequencies. Decimal point position chip, transformer, all components and Complete kit minus power supply. $25.00 is automatic, as is a MHz /kHz indica- full instructions. Same clock kit with .80" Kit $29.95 displays. $22.75 Clock Calendar tion. An exclusive battery saver feature Volt/ohm Probe CT7015 direct drive chip displays date Batt. oper. AC DC to 125 V. 2 pos. volt. and time on .6" LEDS with AM -PM indi- electronically shuts off power to the Digital Temperature Meter Kit and 2 neg. volt. plus continuity. Stainless cator. Alarm /doze feature includes buz- LED display after 15 seconds of opera- Indoor and outdoor. Automatically steel. pocket size. comp. assem. $34.95 zer. Complete with all parts, power supply switches back and forth. Beautiful. 50" tion, making the 1827 ideal and instructions, less case. for field LED readouts. Nothing like it available. service. A touch of the Needs no additional parts for complete, 30 MHz Frequency Counter Kit display button full operation. Will measure -100' to Crystal time base. Covers audio, amateur Hobbiest Electronics Course restores the display for another 15 sec- +200 °F, air or liquid. Very accurate, CB 6.5" digits, prescalable with and band. Beginning course in practical electronics, onds. When operated Complete instructions. by an external $39.95 PC board and full instructions. $55.00 no theory. Lab experiment format. 12 les- Fully wired and tested. power source, DC or AC, the re- $75.00 sons. can be purchased one at a time. display Variable Power Supply Kit $10.00 per lesson mains on continuously. Price is $120.00. 0-12 VDC @I/zA, less than .1% line, load Stopwatch Kit $26.95 For additional information, B regulation. Remote sense capability. Con- Full six digit battery operated. 2 -5 volts. write to &K- stant voltage /circuit limit can be modified 3.2768 MHz crystal accuracy. Times to 60 Hz Crystal Time Base Precision, Dynascan Corporation, 6460 for other V/I ranges. Complete with board 59 minutes, 59 seconds, 99 1/100 sec. Kit $4.75 Converts digital clocks West Cortland Avenue, Chicago, IL and transformers. $24.00 Times standard, split and Taylor. 7205 from AC line frequency to crystal time chip, all components minus case. Full base. Outstanding accuracy. Kit includes: 60635. 1977 IC Update Master instructions. White or black plexiglass PC board, MM5369, crystal, resistors, case. $5.00 capacitors and trimmer, Manual Complete integrated circuit Magnetic Mount for 140 MPH data selector from all manufacturers. 1,234 page master reference guide to Cosmac 'ELF' Kit RCA CMOS Ex- Auto Clock Kit $15.95 The Channel Master Mag -Ne -Tenna is the latest IC's including microprocessors pandable Microcomputer. New PC board DC clock with 4 -.50" displays. Uses Na- a full -size, base loaded mobile antenna, and consumer circuits. 17,000 cross with monitor on PROM included. No hard tional MA1012 module with alarm option. references for easier sourcing of hard to wiring required. All on board including Crystal time base PC boards and full in- providing high performance with 23 and get parts. Special pricing: 524.95, with power supply. Complete kit of parts with structions. Add $3.95 for a beautiful 40 channel sets, AM and single sideband. assembly users manual. $109.00 dark gray case ready to install. This is free update service thre 1977. Domestic The antenna has a 6 -pole, 8 -ounce mag- Lpostage $2.00. Foreign $6.00. Board only $14.95. Special case $15.00 the best value available anywhere! net, and was successfully tested on the TERMS: $5.00 min. order U.S. Funds. Calif residents add 6% tax. FREE: Send for your copy of our 1977 surface of an airplane flying at 140 BankAmericard and Master Charge accepted. OUEST CATALOG. Include 13y stamp. Shipping charges will be added. miles per hour. Its exceptional holding power means it is particularly effective CIRCLE 34 ON READER SERVICE COUPON 12 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com Punch out the big signal from 60 feet up with Shakespeare's Big Stick. The omnidirectional fiberglass base station antenna Shakespeare's that outperforms anything on the 40 channel band. Illuminating 12 times more capture area. And sending Pig StickTMAntei the signalg energygY out to the horizon in a unique, low angle radiation pattern. World famous This half -wave coaxial sleeve antenna incorporates exclusive Shakespeare engineering in fiberglass to outrange taller, heavier metal antennas under all condi- performance. tions. Withstanding ice and winds up to 125 MPH with no damage to

reception_. And pretl ned to a low And right in SWR over the 40 channel band yóu Move up for the big gain with Shake- speare's Big Stick. Pretested. No ground. radials. Works anywhere with any length own backyard of cable. Also available in a low cost, 2- piece model, Big Stick II. xr

ñnä ne. An cómi RCLE 17 ON READER SERVICE COUPON

Big Stick, Style 176 Used as part of this country's DEW line defense system.. Less than $45.

Shakespeare Company /Antenna Group, P.O. Box 246, Columbia, S.C. 29202 In Canaca: Len Finkier, Ltd., Ontario.

www.americanradiohistory.com HEY, LOOK ME OVER This is easy- on vinyl surfaces -even padded vinyl surfaces. Electrically, the Channel Master Mag -Ne -Tenna is a superb performer be- anyone can solder cause it features an in -line, ferrite bead RF choke, a must for vinyl top cars. The WITH choke maintains stable SWR, aids in tuning, eliminates background KESTER SOLDER noise, and

Handymen! Hobbyists! KESTs.wEt

DO-IT-YOURSELFERS! CIRCLE 75 ON READER SERVICE COUPON Let Kester Solder aid you in your home repairs or hobbies. For that household generally enhances performance. Drift item that needs repairing radio, TV, model train, jewelry, appliances, minor -a and RF interference are eliminated. The electrical repairs, plumbing, etc. - Save money - repair it yourself. Soldering with Kester is a simple, inexpensive way to permanently join two metals. antenna is fully -weather -protected; A 24 foot length of coaxial cable is furnished go Class" use Kester Solder. When you Solder "First - for simplified installation. When not in For valuable soldering information send self-addressed stamped envelope to use, the Mag -Ne -Tenna is easily removed Kester for a FREE Copy of "Soldering Simplified ". from the surface of the vehicle, leaving no tell -tale signs for CB thieves. Model 5029; list price, $34.95. For further in- KESTER SOLDER formation, contact Channel Master, El- Litton 4201 WRIGHTWOOD AVENUE /CHICAGO, ILLINOIS 60639 lenville, NY 12428.

CIRCLE 13 ON READER SERVICE COUPON Rapid Hide -Away Antenna The Hustler "Hustloff" instant re- Revolutionary New Wiring "Pencil" Makes moval, store -in- the -trunk, instant remount antenna has performance equal to most permanently mounted mobile installations! The special design trunk lip Interconnections mount firmly clamps to any trunk lid with the twist of a knob. is in 1/3 the Time! Operation CIRCLE 72 ON READER Create Finished Wired Circuits II SERVICE COUPON in Hours, Not Days For Breadboarding, Prototypes and Production Interconnects Circuit Elements in Digital and Analog Circuits Easy for anyone - just hook up your components using the insulated "solder

thru ' wire (your choice of blue, red, green or clear). Wire feeds off a replaceable spool thru the P173 tool body and out of a steel tip so fine it easily routes wire around even the smallest I.C. lead. A touch of the iron, with solder, completes instant and easy. Positive grounding is the joint. assured with the heavy duty, case -hard- Available accessory items include P179WS Wire Spacers ened clamp assembly. Mounted antenna for neat routing, tenth -tenth Micro-Vectorbords., circuit be Padbords and frames, like the 3677 -6 and 51X -1. Order a cannot removed when trunk is closed. P173 Now! Supplied with two 200' spools of AWG solder Deluxe features include a 180 degree thru wire (1 red, 1 green), complete instructions. $950 swivel for positioning antenna to opti- At your Vector distributor U mum vertical location, 17 -ft. coax with Mail orders, shipping and handling charge. add $2 all connectors factory attached. The California residents add 6% sales tax. sa Hustloff antenna is available with 48 -in. '4'771 standard and 55 -in. heavy duty stainless steel antennas. Price is $28.95 for the W P DIVISION VJ X74 J C HT -27 and $31.25 for the HHt -27. Ad- ELECTRONIC COMPANY, INC. ditional information may be obtained from New -Tronics Corporation, 15800 12460 Gladstone Ave. Sylmar, CA 91342 (213) 365 -9661 Commerce Park Drive, Brookpark,OH. CIRCLE 41 ON READER SERVICE COUPON 14 ELEMENTARY ELECTRONICS /September -October 1977 www.americanradiohistory.com President. A whole new class of CB radio. First class. variable mike "614, ® andANL on our least With 40 channels and all the gain and our MIL ,;; ®=ims, expensive units. power the law will allow. sophisticated 11 Maybe a Every single President radio is compression -_ President is more CB thoroughly tested to make sure it circuit fora than you bargained works perfectly before it ever gets out new standard of CB talk power. for. But then... isn't that what of the factory. And every President comes with makes a bargain? Every President model is a little something extra for its price. engineered with quality features like Like 100 mm digital channel readout PRESOCILZ CIRCLE 14 ON READER SERVICE COUPON Engineered to be the very best. PresidentBectrorvcs, Inc. 16691 Hale Avenue Irvine, CA 92714 (714) 554 -7353 In Canada: Lectron Radio Sales Ltd., Ontario

www.americanradiohistory.com FoRao wN looked up-be it American, European, Japanese, Taiwanese, or whatever -and immediately referenced to which of the six PERSOaNAL major manufacturers of general replacement parts makes it. And even more than COMPUTING that, the user can also check out the basing diagrams for all listed units. So now the needless running around, the headscratch- POWER Only ing, the costly guesswork can all be eliminated; at least one of these replacements is carried by every parts jobber in the coun- Math Unraveled. For those people baf- try. And all their parts are cross -referenced fled by math, here is the book that takes in the same easy -to -use master guide! Pub- math out of the twilight zone and into the lished by Tab Books, Blue Ridge Summit, sunlight of everyday use. Mathematics PA 17214. Unraveled -A ' New Commonsense Ap- proach by James Kyle tells the how and Old But Good. Here is the fourth edition why of mathematics, and best of all, how of an old favorite, Tape Recording for the to really enjoy mastering math. It's written Hobbyist by Art Zuckerman. His text is in an easy -to -read style, and it's backed written especially for the hobbyist, not the with up by nearly 100 practical illustrations. professional. In non -technical language, it Here's what Kyle says in his Preface: discusses numerous types of recordings and MOTOROLA'S EDUCATOR II "Since first becoming interested in elec- explains the method used to make each of MICROCOMPUTER HEP KIT tronics, I have been forcibly reminded them. The author shares his knowledge of (every time I have to calculate a voltage, tape recorders. helping the reader to Motorola M6800 Technology current, or power level) of the importance Test -as- you -build in easy steps - normally one evening assembly of mathematics to today's technology." Completely self- contained with toPedate all parts, cabinet and instructional manual ec Learn MPU theory and programming as you build, and then get ready to expand ~ " your computing power with these new C, '°a accessory kits that will be coming soon - Video Display Card / Keyboard Kit Soft cover Module Card Rack and Power Supply 160 pages Memory Modules $4.95 Application Programs on Cassettes Soft cover 280 pages best Also available... $6.95 choose the recorder and techniques suited to a particular purpose. Practical MOTOROLA HEP EDUCATOR II situations are covered -field recording, us- Kyle presents the subject in a logical, ing the recorder at a party, editing and progressive, building -block way that lets producing tapes, producing special effects, POWER SUPPLY!T the reader assimilate knowledge as he making movie and slide show tracks and reads. It's a fact -packed, entertaining his- maintenance tips. Published by Howard tory of the development of the art. Also, W. Sams and Co., Inc., 4300 West 62nd it's right into that controversial New Math. St., Indianapolis, IN 46268 The reader will be surprised to find that he knows most of it already. And what he 8080 Designer's Guide. A new design- doesn't know is explained simply with er's guide covering the applications of pro- words and illustrations. Then the relation- ships of numbers, equations, and mathematics are explained. There is much more. Designer's Guide Write to the publisher for the book cata- to Programmed log. Published by Tab Books, Blue Ridge 5 V a 1.0 Amps Logic Summit, PA 17214. Designed specifically for Educator II 8080 Microprocessor Microcomputer Kit Kit parts, cabinet Complete - all Substitution Guide. Here is a super - manual and construction colossal six -in -one guidebook with a today for more information about one -stop cross reference list for the simpli- Send Soft cover Educator II fied replacing of over 80,000 transistors and integrated circuits labeled with manu- 148 pages Please print label clearly. $7.50 grammed logic and featuring specific uses NAME of 8080 type microprocessors deals primarily with design and documentation of 8080 ADDRESS microprocessor subsystems. Illustrated with drawings and tables, the guide contains numerous sample programs and ex- CITY periments, demonstrating programming and program /hardware integration. Titled The STATE ZIP 1q41 une Clou newts-use mawai Ina, Designer's Guide to Programmed Logic Tns e,ee,ro.e Soft cover moots blot o.e ü S featuring the 8080 Microprocessor, cov- Woo bapfupanr. 518 pages it MOTOROLA $7.95 ers desgin and engineering approaches to 114A Semiconductor Products Inc. microprocessors as developed by Pro -Log HEP/MRO OPERATIONS facturer's parts numbers. It's Master Tran- and used to design its own MPS 880 \705 West 22nd Street -Tempe, AZ. 85282` sistor /IC Substitution Handbook. Now product line. Discussed in the Implement - virtually any part number can quickly be (Continued on page 19) CIRCLE 19 ON READER SERVICE COUPON 16 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com THE GREAT UPRISING! 4gtsw4,_Di - "HOorimu PIGIFON7 the first all- indoor CB base antenna with all -out performance.

The "Homing Pigeon" is your antenna answer to . operating CB from any location, condominium, office, home, apartment, motel etc. No installatMon required; antenna is supported between floor and ceiling like a pole lamp. Communications range is equal or superior to better mobile installations. The "Homing Pigeon" incorporales a unique method of easily and quickly adjusting SWR. One settling covers all "the home of originals" channels for outstanding performance with any 23 or 40 channel CB rad o, AM or SSB. Antenna is supplied complete with 17' coax, connectors attached, liesTOit ready to use. Model HP -27. AVAILABLE FROM ALL DISTRIBUTORS WHO RECOGNIZE THE BESTI Patent for "Homing Pigeon' applied for by New -Tropics. Other Hustler antennas are protected by one or more New -Tronics patents: 3287732, 3513472, 3327311. 3419869 ,35992,4.3873985,3582951.

neuu 15$00 commerce park drive AVAILAaLI: IN CANADA FROM- - tronics brook par -c, ohio 34142 (216) 267 -3150 superior Model HP -27 __corporation - SUPERIOR ELECTRONICS INC - CIRCLE 12 ON READER SERVICE COUPON www.americanradiohistory.com Americans have been using Motorola`. 2-way radios to find campsites for years. synthesizer provides precise tuning (automatically, of course). A professional- quality 3 %2- inch top -fire speaker ives the Motorola B an audio quality that must be heard to be fully appreciated. And every Motorola CB gives you the added advantage of a power mic that doesn't need batteries. That doesn't cost 50 bucks extra. It's a fact that the people who first The Motorola 40- Channel CB radio. put radio on wheels also made the first We believe it's the most sensibly radio on wheels on the moon. engineered CB radio on the market. We believe But it's not surprising. it will deliver years of service Because Motorolá makes more at a level of performance few could match. radios for police, firemen, taxis, and lunar Put a Motorola rovers. CB radio under your And now Motorola makes a dash and you'll 40- Channel CB radio that shares much more believe, too. than a name with our professional 2 -way radios. The clean, uncluttered lines of the Motorola CB, for instance. Features that many manufacturers leave on the outside of their sets (or don't offer at all) are built into a Motorola CB. Gain control, noise limiting, audio compression, even a TV interference filter are built-in, fully automatic circuits that actually make communication better. And operation easier. A digital phase lock loop

From the voice of experience in 2 -way ra

To find the dealer nearest you, write: Customer Relations Manager, Motorola Inc., Automotive Products Division, 1299 East Algonquin Rd., Schaumburg, Illinois 60196. Motorola is a registered trademark of Motorola Inc. CIRCLE 23 ON READER SERVICE COUPON www.americanradiohistory.com BOOKMARK Telephone Accesso!ies (Continued from page 16) ThE BOOK y0U'VE YOU CAN BUDD ing Programmed Logic section are: the Alb X ui»a NExAGtïCIMA FO R scientific approach to problem solving; AlpITED both system design and modular approach- 72,c6 HERE! es to microprocessor use: how to use ° Is multi -level modules; and program listing, Pu ING ODE Q VOJ labels and patching. An extensive section INDEX1i, REGISTER QPIr is devoted to programming applications TA GP Soft cover Pov that includes detailed examination of the oy QP use of sub -routines and different addressing 84 pages N Q EPpGMs modes available in the 8080 microproces- $3.95 sor. Also covered are timing, counting, Build opens the door to a world of tele- compare, logical operations, and arithmetic phone electronics for hobbyist and techni- applications. Contact Pro -Log Corp., 2411 cian alike. Published by Hayden Book Garden Road, Monterey, CA 93940. Company, Inc., 50 Essex St., Rochelle Park, NJ 07662. More Than Pot Luck. Now you can cook up delectable programs with this mouth- Manual For Scientific Calculators. Do watering gourmet's delight of all new you want to get the most out of your "6800" software. Scelbi "6800" Software scientific calculator? Well, now you can Gourmet Guide and Cook Book is now with help from a new manual just pub- available and tells how to use the original lished by TK Enterprises. Everything manufacturer's recommended mnemonics You've Always Wanted to Know About and assembly formats, with hexadecimal RPN But Were Afraid to Pursue is a com- notations. General purpose routines for pact manual that devotes an entire section multiple precision operation. Programming to Reverse Polish Notation (RPN) , the time delays for real time applications. most efficient technique for expressing complex calculations. Divided into two parts, this comprehensve text first describes the basic operations of the Corvus 5110 calculator, which is also functionally iden- UMERST4NDING Everything yotivel always wanted to know about RPN xll ry ír:SO , II Soft cover r:LICBD 200 pages $9.95 CUNPUTEßS AND SMALL COMPUTER SYSTEMS Random number generators. Completely Soft cover Here, at last, is a profusely illustrated, assembled relocatable floating point arith- easy -reading, "must" book explaining funda- 118 pages mental metic program, with 23 bit concepts behind operation of signed man- $7.50 almost all microcomputers ... in simple tissa and 7 bit signed exponent. Input/ English... giving you that extra knowledge output processing for basic 1/0 program- tical to the APF Mark 55 and OMRON to read and understand computer magazines ming. Interrupt processing. Code, numeric 12SR and manufacturer's literature ... and feel calcualtors. The second part of the "at home" around computers. Things like: conversion routines. Real -time program- manual presents a selection of application How a CPU is organized; how it follows ming. Search and sort routines. And too problems and their accompanying solution sequences of orders to solve problems many more goodies to mention here. Pub- programs. Typical problems are demon- I lustrates basic instructions from lished by Scelbi Computer Consulting Inc., strated in almost every microcomputer Discusses financial, statistical and simple common memory addressing modes - 1322 Rear Boston Post Road, Milford, algebraic calculations. Problems illustrated illustrates typical uses What to know to CT 06460. should pyove useful to all who use a tell a computer what to do when using scientific calculator. The manual is machine language programming Use of avail- flow charts; program worksheets; hand Adding on to Ma Bell. Already one of able directly from the Publisher, TK En- assembly of source codes into object codes; the most common and useful of all home terprises, 16611 Hawthorne Boulevard, memory maps; purpose of Editor, appliances, the telephone has the potential Lawndale, CA 90260. Assembler, Monitor. of being much more than simply a com- only $995. Order your copy today! municative device. It can remotely control How a computer communicates other appliances, automatically dial any Commonly used I/O devices and number (police, fire department) when operational concepts Practical aspects of selecting a small computer system Plus, triggered by an alarm, code phone con- hundreds of other practical facts and versations to insure privacy, even act as information! If you're curious about small a burglar alarm when equipped with the computers, you must own this 300 page proper accessories. But up to now, these no- nonsense easy- reading text. Includes easy -to -use glossary of key microcomputer - accessories have had to be purchased at oriented words. prices ranging from $30 to $200. Jules H. UNDERSTANDING MICROCOMPUTERS. The Gilder, in the first guidebook of its kind, name says it all! Only $9.95 ppd. now shows how to build these accessories, Order your copy today! and at a small fraction of their retail cost S(EIB1 (OMIIIIER -many for less than $5. Telephone Ac- cessories You Can Build includes the (ONSlJIIING IN(. P.O. Box 133 - PP STN, Dept. EE basics of telephony and pertinent tele- Milford, CT 06460 phone regulations. The easy -to- follow plans Price shown for North American customers. Master Charge. Postal and Bank Money Orders preferred. it provides are all geared to practical ap- Personal checks delay shipping up to 4 weeks. plication. Containing useful schematics, Pricing, specifications, availability subject to change without notice. SCELBI Books are avail- basic building tips, and printed circuit able in many fine Computer Stores. layouts, Telephone Accessories You Can CIRCLE 36 ON READER SERVICE COUPON

ELEMENTARY ELECTRONICS /September- October 1977 19 www.americanradiohistory.com NEW LSI TECHNOLOGY FREQUENCY COUNTER EE -OF- THE -ART COUNTER FEATURING THE TAKE ADVANTAGE OF THIS NEW STATE MANY BENEFITS OF CUSTOM LSI CIRCUITRY. THIS NEW TECHNOLOGY APPROACH TO INSTRUMENTATION YIELDS ENHANCED PERFORMANCE, SMALLER PHYSICAL SIZE, DRASTICALLY REDUCED POWER CONSUMPTION [PORTABLE BATTERY OPERATION IS NOW PRACTICAL], DEPENDABILITY, EASY ASSEMBLY AND REVOLUTIONARY LOWER PRICING!

SIZE: e6\Gs` 3" High 6" Wide 51/2" Deep

FEATURES AND SPECIFICATIONS:

13/4 LBS. DISPLAY: 8 RED LED DIGITS .4" CHARACTER HEIGHT COLOR: GATE TIMES: 1 SECOND AND 1/10 SECOND BLACK [AUTO DEC. PT. PLACEMENT] RESOLUTION: 1 HZ AT 1 SECOND. 10 HZ AT 1/10 SECOND. FACTORY DIRECT PRICES FREQUENCY RANGE: 10 HZ TO 60 MHZ. [65 MHZ TYPICAL]. SENSITIVITY: 10 MV RMS TO 50 MHZ, 20 MV RMS TO 60 MHZ TYP. KIT #FC -50C 60 MHZ COUNTER WITH CABINET & P.S $99.85 INPUT IMPEDANCE: 1 MEGOHM AND 20 PF. KIT #PSL -350 350 MHZ PRESCALER NOT SHOWN[ 23.95 [DIODE PROTECTED INPUT FOR OVER VOLTAGE PROTECTION.] KIT # PSL -650 650 MHZ PRESCALER NOT SHOWN] 29.95 ACCURACY: + 1 PPM I+ .0001 °,1:AFTER CALIBRATION TYPICAL. STABILITY: WITHIN 1 PPM PER HOUR AFTER WARM UP [.001 XTAL MODEL #FC-50WT 60 MHZ COUNTER WIRED, TESTED & CAL. 165.95 IC PACKAGE COUNT: 8 ALL SOCKETED] INTERNAL POWER SUPPLY: 5.2 V DC AT 800 MA. REGULATED. MODEL #FC- 50 /600WT. . 600 MHZ COUNTER WIRED, TESTED & CAL. 199.95 INPUT POWER REQUIRED: 8 -12 VDC OR 115 VAC AT 50/60 HZ. KIT NFC -50C IS COMPLETE WITH PREDRILLED CHASSIS ALL HARDWARE AND STEP -BY -STEP POWER CONSUMPTION: 4 WATTS INSTRUCTIONS. WIRED & TESTED UNITS ARE CALIBRATED AND GUARANTEED. PRESCALERS INPUT CONNECTOR: BNC TYPE WILL FIT INSIDE COUNTER CABINET. 60 HZ. PLEXIGLAS SEE THE WORKS Clock Kit CABINETS Clear Plexiglas Stand XTAL TIME BASIL Will enable ' for or any LED Great Clocks 6Big 4" digits Digital Clock Kits SPECIAL PRICING! Digital project. Clear -Red 12 or 24 M. time or Clock-Calendar PRIME - HIGH SPEED RAM Chassis serves as Bezel to . 3 set switches Kits to operate 345 OS increase contrast of digital Plug transformer from 12V DC. parts included .0111 ABINET I displays. all 1 "x2 "PC Board

Plexiglas i5 Power Red : 5 -15V -3 ekoe%s Y4 Black, White or 21L02 3 "H,6 "W,5 % "D Pre -cut & drilled (25MA TYP.) LOW POWER - FACTORY FRESH CABINET II Clear Cover Easy 3 wire hookup Kit N850 -4CP Accuracy: ! 2PPM 1 -24 $1.95 ea 100 -199 $1.60 ea $6.50 ea 25 -99 1.75 ea 200 -499 1.45 ea 2Y2 "H,5 "W,4 "D Size. 61-1,4 1/2"W,3"0 #TB -1 (Adlustable RED OR GREY PLEXIGLAS FOR DIGITAL BEZELS ASVPEP Lf Complete Kit '2350 2/'45. C`OOK $495 OVER 500 PCS. $ 1.39 ea. 3 "x6 "x1/8" ' E ea ' it & Cal .9.95 JUMBO DIGIT CLOCK I-1_I111_111 j+=j_I1\'1111_111111 1\11 I featuring : _ A complete Kit (less Cabinet) OR E - TIME- 517 "" - ;31_130-11 ; MORE KU Inni six .5" digits, MM5314 IC 12/24 Hr. FOR THE BUILDER THAT WANTS THE BEST. FEATURING 12OR24 HOUR TIME - time, PC Boards, Transformer, Line 29-30-31 DAY CALENDAR. ALARM. SNOOZE AND AUX. TIMER CIRCUITS Cord, Switches and all Parts. Ideal Fit in II Will alternate time 18 seconds) and date 12 seconds) or may be wired for time or date display only, Cabinet with other functions on demand. Has built -in oscillator for battery back -up. A loud 24 hour alarm Kit #5314 -5 ,995 2$38. with a repeatable 10 minute snooze alarm, alarm set & timer set indicators. Includes 110 VAC /60Hz power pack with cord and top quality components through-out 77 JUMBO DIGIT $095 ea. eo 70010 06 4f CONVERSTION KIT 7 KIT-70019 WITH 6 -.5 ..539.95 DISPLAY IN" p),i .. ' "DIGITS Convert small digit LED clock to large KIT - 7001C WITH 4 -.6" DIGITS Fr 2'' Aid-P8 2- .3 " DIGITS FOR SECONDS ..... $42.95 .5" displays. Kit includes 6 - LED's, KIT -7001X WITH 6 -.6 "DIGITS ..545.95 01282 qS 3 Q a NQ©® Multiplex PC Board & Hook up info. ARE Kit #JD -1CC For Common Cathode KITS COMPLETE ILESSCABINETI :, : x DISPLAY 7001 e DISPLA1 Kit #JD -1CA For Common Anode ALL 7001 KITS FIT CABINET I AND ACCEPT QUARTZ CRYSTAL TIME BASE KIT N T: - 1 PRINTED CIRCUIT BOARDS for CT7001 Kits Specify for7001 sold separately with assembly into. PC Boards are llll_"1;111_ _=11 _"1 : drilled Fiberglass, solder plated and screened B,CorX -57.95 with component layout. 1212414'R VARIABLE REGULATED AUTO BURGLAR MODEL 12 VOLT AC or 01 j5 1 AMP DC POWERED ALARM KIT POWER SUPPLY KIT #2001 N EA, 1O ASSEMBLE ANO EAST TO INSTALL II NOT 6 JUMBO .4" RED LED'S BEHIND RED FILTER LENS WITH CHROME RIM M PROVIDING MANY FEATURES . VARIARLE FROM .% to t 4 FOUND KEYLESS ALARM HAS HIDDEN 12/24 -Hr. TIME FORMAT NORMALLY . SHORT CIRCUIT PROOF SET TIME FROM FRONT VIA SWITCHES PRO015,05 FOR POS S GROUNDING STYLISH CHARCOAL GRAY CASE OF MOLDED HIGH TEMP. PLASTIC SWITCHES OR SENSORS WILL PULSE HORN 723 IC REGULATOR RELAY AT 'HZ RATE OR DRIVE SIREN KIT 21,43055 PASS TRANSISTOR BRIDGE POWER INPUT CIRCUITRY - TWO WIRE NO POLARITY HOOK -UP PROVIDES PROGRAMMABLE TIME DELAYS Key in Car, AT T Amp OPTIONAL CONNECTION TO BLANK DISPLAY [Use When Off Etc.] FOR EMIT ENTRY 4 ALARM PERIOD UNIT . CURRENT LIMITING TOP QUALITY PC BOARDS & COMPONENTS - INSTRUCTIONS. MOUNTS UNDER DASH REMOTE SWITCH KIT #ALR -1 KIT IS COMPLETE INCLUDING CAN BE MOUNTED WHERE DESIRED CMOS DRILLED b SOLDER PLATED MOUNTING BRACKET INCLUDED RESISTS FALSE ALARMS 4 RELIABILITY $9.95 PC KIT 42001 PROVIDES FOR ULTRA DEPENDABLE ALARM FIBERGLASS BOARD AND 115 VAC DO NOT BE FOOLED BY LOW PRICES' THIS IS #ALR -1 WT ALL PARTS (Less TRANS. COMPLETE KIT Powerpatk25A Tir WITH ALL PARTS $2915 MORE TOP DUALITY COMPLETE FORMER) KITRPS-01 $8.95 [Less 9V. Battery] $2795EA. NAC -1 INCLUDING DETAILED DRAWINGS AND IN WIRED& STRUCTIONS OR AVAILABLE WIRED AND TRANSFORMER 24v CT will ASSEMBLED UNITS WIRED & TESTED $3995 3 OR N 96 TESTED TESTED provide 300MA al 12V and ORDER 62001 WT (LESS 9V. BATTERY] EA. MORE 37 EA. $19.95 1 Ampai 5V. $3.50 Wired for 12 -Hr. O.. if not otherwise specified.

ORDER BY PHONE OR MAIL OPTOELECTRONICS. INC. 0115 COD ORDERS WELCOME ealos MINICBMO Orders Under $15 Add $1.00 Handling BOX 219 HOLLYWOOD. FLA. 33022 13051 9212056 Fla Res. Please Add 4% Sales Tee. S. 21 AVE WE PAY ALL SHIPPING IN CONTINENTAL USA - OTHERS ADO 5% [ 10% FOR AIRMAIL! CIRCLE 21 ON READER SERVICE COUPON

www.americanradiohistory.com For the ox central serious CB'er... reporting an indoor antenna A world of SWL info!

BY DON JENSEN Called the Antenna!Went PBS 3 D Direct satellite to home television broadcasting is technically possible now, The Pacer people cfter The only indoor gain base although just when this technology actually will be put to use for more than ex- station antenna on the market designed especially perimentation remains to be seen. for apa-tment dwelling CB'ers. Lightweight, portable Tests and demonstrations conducted at and POWERFUL, the E4" AntennaMent is free the Montreal headquarters of the Canadian Broadcasting Corporation (CBC) have standing and completely collapsible. Made of shown that excellent color television recep- Pacer's Mil tary grade fiberglass, this base antenna tion is possible directly from satellites using a small dish type antenna, about two goes anywhere indoors and outdoors a transceiver feet across. The CBC has conducted its can gc. The AntennaMent handles 500 watts and tests using its communications technology operates across all 43 channels with an SWR 1.2:1. satellite Hermes, which for the past year - of and -a -half has been hovering in a geostationary orbit 22,300 miles out in space. For travelers, campers and stay -at-home CB buffs, Hermes and two other communications satellites are featured on a brand new QSL another Pacer quality product ... for the serious card now being issued by the CBC's Radio CB'er. Canada International. One of these featured satellites is Alouette I, the first of four Canadian satellites designed to carry out Suggested retail price S34.95. ionospheric studies. It was launched from Vandenberg AFB, Calfiornia, back in 1962. Its primary purpose was to measure the earth's ionosphere from above. It was Quality and performance called, therefore, a "topside sounder." The signals sent back from this satellite pro- across 40 channels ... for the duced a sort of radar map of the iono- serious CB'er from sphere. The ionosphere, by the way, is that region beyond the atmosphere from which shortwave signals are bounced back to earth, thousands of miles away from the transmitting antenna. Alouette I -named after a high flying Canadian song bird of Pacer the lark family -is expected to orbit the 44 earth, some 625 miles out, for another Manufactured in the USA. 2,000 years. Progress, Inc. Brotherly Satellite. Also pictured on 3321 N.W. Radio Canada International's new QSL is 79th Avenue Anik I, a third communications satellite Miami, Florida 33122 launched in November, 1972. It was the world's first domestic geostationary corn - munications satellite, providing television, CIRCLE 26 ON READER SERVLCE COUPON telephone and data transmssion links to all parts of Canada. It offered, for the first time, live television service (rather than in kilohertz. He should also include some and 9,655 kHz) and 0400 (5,960 and videotaped programs run days later) to the brief details about the content of the pro- 9,655 kHz), and 0400 (5,960 and 9,655 TV stations in the larger communities of gram heard. The card is then mailed to the kHz), GMT. the Canadian North. CBC's Radio Canada International head- The new QSL card is very attractive and Anik is parked over the equator, south quarters in Montreal. a fine addition to any SWL's collection! of Calgary, Alberta. Its parabolic antenna If the details on the card are correct, the End of a Clandestine. Forty years after can "see" all of Canada. reception will be verified and the card will it first began broadcasting -though with The attractive blue and white satellite be returned to you as your QSL. Cards two breaks in those four decades-the QSL card is now available to those SWLs with incorrect reception details will not be Voice of the Basque Resistance, Radio who tune Radio Canada International returned. If you have not received a Radio Euzkadi, ceased 'operations on April 30, shortwave programs. Under the QSL policy International program schedule and blank according to an official European source. begun last year by Radio Canada Interna- 1977 satellite QSL card, you can get one In 1937, Radio Euzkadi (pronounced tional, the listener may receive one QSL by writing to Radio Canada International, ooze -kandi) went on the air from Bilbao in card per year. The blank QSL card is Post Office Box 6000, Montreal, H3C 3A8. the Basque region of northern Spain. In a mailed out with the Radio Canada Inter- Radio Canada International has a full bid for Basque loyalty in the civil strife, national summer -fall 1977 program sched- shortwave schedule, but, for starters you Madrid's Republican government granted ule. When a listener tunes a Radio Canada can look for half -hour English language the Basques. semi -autonomy. But ten International program, he fills in the card programs at 0100 (9,535 kHz), 0200 months later the Basque republic had with date, hour of reception and frequency (9,605, 0,655 kHz), 0300 (6,000, 9,605 crumbled before the armies of Francisco

ELEMENTARY ELECTRONICS /September- October 1977 21 www.americanradiohistory.com DX CENTRAL Franco and his German and Italian allies. Radio Euzkadi was silenced. A Basque government in exile was QSL formed in Paris. When World War II Radio Canada began and the Nazis took the City of Lights, the Basques fled again, this time to International the U.S. After the war, the exiled Basque leaders set up shop in France. Radio Euzkadi was born in December, 1946. From that time until mid 1954, the station operated from on board an old Radio Canada's new fishing trawler in the harbor at Bayonne, satellite QSL card. France. Transmitters were low powered Three of Canada's sat- and the station was not audible in the ellites are featured on U.S., although European SWLs logged it the card, and the back on either 6,300 or 7,000 kHz on occasions. contains space for ver- When the Basque struggle against the ification information. Franco regime began to heat up, the Span- ish government applied political pressure on France, which had until then, closed its eyes to the clandestine broadcasts corn- tained the fiction that it somehow operated country, Radio Euzkadi can withdraw from ing from its territory. The French were secretly from the Pyrenees Mountains in the air with honor. pressured into silencing Radio Euzkadi. northern Spain. Apparently the Venezuelan Thus ended one of the most interesting A reborn Radio Euzkadi returned to the government also chose to look the other clandestine broadcasters of the past 40 air a third time, probably in 1965, with a way and spokesmen denied any knowledge years. shortwave transmitter on about 13,250 of the station or its whereabouts. Trans World Radio, Guam. Scheduled kHz, a frequency it used right up to the And so Radio Euzkadi operated until to begin in June or July, so probably on end. Later a second transmitter was added, the end of April. Apparently with the the air by the time you read this, is the which used several frequencies, but wound Basques winning some concessions from fourth and newest of the Trans World up on about 12,105 kHz. The stations the new regime in Madrid it was time to Radio stations on shortwave. claimed to be using transmitters running take a lower profile. SWLs are, no doubt, familiar with Trans 80 kilowatts. In its closing announcement, Radio Euz- World Radio stations at Monte Carlo,

This time the station appeared to be kadi said it was ending its operations "to Monaco; . Bonaire in the Netherlands An- transmitting from the northern coast of prepare for our appearance on the soil of tilles, and in Swaziland in southern Africa. South America, almost certainly Vene- our own land in freedom. . . . Since the The latest addition to the family of zuela, although its location was never of- Basque national flag is once again flying religious- oriented shortwave stations is ficially disclosed. Instead, the station main- proudly from all mastheads in the Basque KTWR on the island of Guam in the

TT I' THIS ADVERTISEMENT IS ONLY A SAMP E OF THE THOUSANDS OF SURPLUS BARGAINS AVAILABLE - SEND FOR OUR FREE CATALOG OR RELIEVE ONE WITH AN ORDER! TTT, DRINK INPUT /OUTPUT TERMINAL FANTASTIC SPEAKER CABINETS TV TENNIS GAME KIT T MIXER Fantastic air -suspension enclosures, de- KIT signed for direct dispersion of the hi -fre- ; Through a lucky pur- s +'- - , quency driver and wide dispersion of the chase we obtained some pap woofer. By adding the speakers below -r O ©o you can obtain a frequency response of 0 'ei new drink mixer parts. s ©Y We have all parts except EWE 30 to 20,000 Hz. Sold in matching left T - AS Is" the top cover, and right -hand pairs, with grill cloth and but you rum 1 or 2 players - 1 to ball speed dual -.T can OÍ3LI instructions. Size: 17" x 10'/: x 9'/: deep. make your own or paddle size - sound. These games were 000 Requires an 8" woofer and 4" tweeter. operate without it. Now you can build a never finished at the factory. You do a Sh. Wt. 25 Lbs . 70670200 .$25.00 /pair $20.00 mixer for under $5.00. Great for O ©® little soldering and mounting to complete 4 pair for $80.00..70870200. $80.00/4 shakes, kids love 'em. Includes motor, The IC board is al- the work left undone. fi mixer, screws, line cord, stand, switch + 4141L, has i SPEAKERS ready assembled and passed Q. C. Just and 16 oz. mixer cup. add some hardware to complete the pro- aó and } Sh. Wt. 5 Lbs. . . .7M370053. . . .$4.88 ject: a TV game for under $10. Complete A great place to start for building a Spare MIXER CUP for above: CABINETS with instructions, qty. ltd. Sh. Wt. 4 Lbs. m microprocessor. These units were part Sh. Wt. 8 oz. ..7M370054.. $1.50 each COMPONENT SPECIAL! 7ZÚ70250...$8.88 ea .. $69.99 for 10 of a comlex computer system. The term- e T The super cabinets described above, plus filna conans:contains: keyboard;e CRT; drive cir- m JOYSTICKS y 2 woofers, 2 tweeters, 2 crossover net- TV cuits; ASC1 1 output; and a complete } Two POT'S works, grill cloth and instructions. Build 128 page technical manual with operas- REMOTE Í / m Super for X -Y funs- own and save! ing and repair instructions, which makes your CONTROL 10 ions: audio, computer, Sh. Wt. 35 Lbs..7ZU70242. $49.50 /set it easy to modify the terminal for your UNIT m (emote control, graph- applications. (Character generator was TOUCH -TONE A universal control unit operates your r acs, etc. Sh. Wt. 8 oz. of a separate control section which TV at your command from up to 35 feet m 7J70163 $4 95 part GENERATOR is not supplied. The terminal can be CHIP away. Fits all sets with standard VHF T used when modified using character gen- turret tuners, changes channels as well as POWER New, 2 of 8 encoder chip ME8900, (sim- m C' erator LSI chips, such as the 2513, 2516 turning TV on or off. New, with instruc- SUPPLY filar to the MC144101. Sold with data other such IC's). [ions. Qty. Ltd. Sh. Wt. 15 Lbs. KITS ta1;y1, or sheet on uses of MC14410 chip.p. No m The keyboard is a 50 key al ha- numer- 7M170225 .. $39.95 ea... $150.00 for 4 1. C.B. POWER SUPPLY KIT y p crystals required. Sh. Wt. 8 oz. is (and others) block keyboard, with TV A complete kit which puts out 10 to 24 7VL70160...$6.95 ea... $60.00 for 10 COLOR CHASSIS ai ASCII output. Display capactiy is 768 TS -951 & TS-953 VDC at 2 amps, regulated, 115 VAC in. MM5240 STATIC CHARACTER r (12 lines of 64), 384, 256, 128 and so have found some 2,000 TV chassis Can be wired for coolant 13.8VDC, ideal GENERATOR CHIP We m on, depending on character size desired. that were damaged enroute to mfr. They & compact for C.B. Kit includes PC card, 64 - 8x5 characters, 2,560 -bit. With data. r The character size may be adjusted from were intended for use in late model sets, components and instructions .. . just add Sh. Wt. 8 oz... 71070231... $6.00 ea . m approximately typewriter size up to '' /.' and all solid state. Most have cracked your own case. Super as a bench supply! are ! The viewing screen of the CRT utilizes TV to MONITOR INTERFACE KIT PC Sh. Wt. 6 Lbs....6C60498....$14.88 boards or bent frames, etc. Parts a- ' a high contrast, low persistence, emerald TV game board allows interface of any lone are worth 5 times as much as our R 2. 5A, 10 to 24VDC Reg. P.S. KIT T green phosphor. Each character is com- TV as a video monitor for computer use. low prices. All units are sold "AS IS ", all A simple, adjustable regulated power sup- posed from a 5 x 7 dot register- With power supplypp & data for 300/75 sales are final. 13" & 15" chassis include m ply. Kit includes all components, vector p pPattern, 9 y clearly and sharply against a dark ohm. Home brew money- saver! 3 Lbs. tuners. Sh. Wt. 12 Lbs. each. r, board and complete schematics. All you Ing background. Controls provided include: 7ZU70213 ... $5.00 ea ... $27.88 for 5 13" Chassis 7DZ70059 $22.50 add is the case. A powerful supply! ...... á on /off; brightness; focus; and character 15 Chassis ... 7DZ70060 . . . .$22.50 ; Sh. Wt. 15 Lbs . . .6M160301. ..$14.88 PHONE ORDERS WELCOME! height. 17" Chassis ... 7DZ70061 .... $14.88 3. 0 to 30V AC /DC P.S. KIT Bank Americard, Master Charge and I. Great as a microprocessor input & out- 9 12" Chassis ... 7DZ70062 .... $14.88 T, This highB ampp adjustable supplypp is an American Express Accepted. I y put device. The display stations are used, of !easy kit to build. It includes a 0 to 40 removed from airline reservation sys- Phone: 1617) 531 -5774 / 532 -2323 B &F ENTERPRISES New volt nsform other c 24V 5A r tems, hotel reservation systems, stock 510.00 Minimum on Charge Orders 119 FOSTER STREET Under New tformetransformer and all other components. Management ,. exchanges, etc. Sh. Wt. 35 Lbs. Mass. Residents Add 5% Sales Tax. PEABODY, MA. 01960 T, Useful as a battery charger, bench supply or any use requiring high current. NEVER BEFORE at this LOW PRICE! POSTAGE: Please add sufficient postage. SEND FOR F.O.B. Peabody, Ma. 01960 FREE CATALOG Sh. Wt. 9 Lbs . . . .6C60462. . . .$14.50 6N860336 .. $29.95 ea.. $100.00 for 4 A HONE ORDERS WELCOME? - 11171 S31.5774/532 -2327 - BANKAMERICARD / MASTER CHARGE / AMERICAN EXPRESS CREDIT CARDS ACCEPTED 'ORDER TODAY! CIRCIwww.americanradiohistory.com F 9n AN RFAr1FR SFRVICF rfl11Pf1N wire wrapping center

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CIRCLE 38 ON READER SERVICE COUPON www.americanradiohistory.com DX CENTRAL GLOSSARY OF DX TERMS Pacific. At this writing the tentative fall sched- CBC-The Canadian Broadcasting Cor- ule of broadcasts is 1100 to 1500 GMT on poration, the government radio and New 9,575 and 11,705 kHz; 2100 to 2200 GMT television organization of our northern on 15,155 kHz; 2200 to 2300 GMT on neighbor. GMT -Greenwich Mean Time, B &K- PRECISION 15,155 kHz; 2300 to 000 GMT on 11,705 or Uni- and 15,155 kHz; 0000 to 0120 GMT on versal Time. This widely used 15,155 kHz; 0900 to 1100 GMT on 11,780 standard time reference is equivalent kHz; 1015 to 1100 GMT on 11,705 kHz; to EDT + 4, EST or CDT plus five 31/2 digit and 2200 to 2245 GMT on 15,155 kHz. hours, CST or MDT plus 6 hours; Target areas for broadcasts are China, MST or PDT plus 7 hours; and PST the USSR and South Asia, but 'the 100 8 hours. kHz -Abbreviation a kilowatt transmitters should be easily for kilohertz, portable DMM standard unit of radio frequency heard in North America. Reader Feedback. `I've lost HCJB, my measurement signifying a thousand cycles per second. Typical shortwave favorite radio station," writes Steven Shaf- frequencies might fer. "I've lost it in a sea of German and be 6,075 kHz, 9,500 kHz, 11,135 Spanish stations. I think it's the wind cur- kHz, etc. kw- Abbreviation for kilowatt, a rents or something is wrong with HCJB's unit of transmitter. My mother thinks it's mf set power measurement. A kilowatt equals 1,000 watts. because all I have is a whip. My father QSL-A reply from a station, in response thinks like I do. The 49 meter band is the to a listener's report of reception. A only place I could hear them and now I'm QSL,.or verification, confirms that sunk. Could you please help me ?" the SWL's report was correct. a Steven. First, I have to agree Often Okay, colorful, well with your mother that you'd do far better designed postcard, such as the one from with more than just a whip antenna. You Radio Canada Inter- national illustrated. don't have to have a fancy antenna. For SWL- Shortwave listener; one who starters try a 20 to 30 foot length of wire tunes the shortwave a on a portable bands as antenna -too much antenna hobby. rig like yours could tend to overload it. Then try HCJB on one of its other fre quencies, like, say, 9,560 kHz during the Corner' on Sundays." evening hours in North America. That is good news, Mark, and thanks Model 2800 for passing the word along to DX Cen- rr tral readers. A medium wave question from George Industrial Quality Rogers of Chickamauga, Georgia. "Will you please tell me where in Cuba at $99.95! the Radio Progreso relay on 880 kHz and the Radio Caribe relay on 1040 kHz are 31/2 digit bright LED display located and what are the powers of these Completely portable -use it stations." anywhere! The former, George, is located at Pinar runs 10 kw power. Auto -zeroing on all 22 ranges del Rio and of The This well- equipped SWL listening post be- Radio Caribe outlet on 1040 kHz is on the Fully overload protected on all longs to Bart Tammaro Jr., of West Haven, has ranges Islande la Juventud. It a power of only Conn. Not all of it is visible in this shot, 1,000 watts. Typical DC accuracy is ±1% but Bart lists the following receivers: Drake Up the Dial. (Times in GMT, frequen- reading 100% overrange SPR4 and 2C; Halicrafters SX122A, SX133 cies in kHz) 3,385 -One of the more High -/Low -power ohms for and SX100; and a Hammarlund SP600. unusual catches from South America is in- circuit resistance measurements Bill Bergadano of Staten Island, N.Y., France Regions III, a shortwave outlet at or semiconductor checks observes that during 1976 he had some Cayenne, French Guiana. Look for this 1mV, 1µA, 0.1 ohm resolution occassions when he logged stations not one very early, say around .0930 ... 6,130 Full range of optional accessories heard before or since on 41 and 49 meter -CHNX, Halifax, Nova Scotia, Canada, available bands at 11 a.m. to 1 p.m. local time. is one of the handful of private, non -CBC Compare features, performance Bill notes that reception on the lower stations on shortwave in Canada. It had and price...you'll choose the new bands is usually strictly "local" in nature been missing from the air for perhaps a 2800 from the "cost- effective" during the midday period. "What I'd like year. Now it is back. Listen about 1200 ... instrument specialists at to know," Bill asks, "is if we can expect 9,770 -There are unconfirmed reports that B &K- PRECISION. another phenomenon like that soon, and if a new station called Radio Nationale is Available for immediate delivery at in the near future, how many months, due to come on the air on shortwave from your nearest B &K- PRECISION years from now ?" Haiti For now, though, the best -and per- distributor. Some other DX listeners also reported haps the only -way to hear this Voodoo unusual 49 meter band reception when the island in the West Indies is via 4VEH, sun was high in the sky last year. Cape Haitien. In Spanish it can be heard ifj4KPRECISION As to your question, if I knew when around 2300 . . . 11,920 -Radiodiffusion conditions like that will occur again, I'd Television Ivorienne at Abidjan, Ivory use that sort of prognostication talent in- Coast, West Africa, can be heard around DYNASCAN stead to pick race horse winners or Wall 2130 after Radio Nacional Espana signs CORPORATION Street stocks! off. Programs are in an African vernacular 6460 West Cortland Avenue "Dear Don," writes Mark Vincent of language. Chicago, Illinois 60635 312/889-9087 Lockney, Texas, "In an earlier column (Credits: Leon Tannenwald, NY; you mentioned that Radio Canada Inter- Michael Delman, NY; Derek Davey, In Canada: Atlas Electronics, Ontario OH; Intl. Sis: Empire Exp., 270 Newtown Rd. national had discontinued its DX show. Kenneth Earhart, PA; American SWL Plainview, LI, NY '1803 Well, Radio Canada International, starting Club, 16182 Ballad Lane, Huntington June 4, has a new DX show entitled, `DX Beach, CA 92649) CIRCLE 7 ON READER SERVICE COUPON 24 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com When the world tal you can listen.

EALISI/G - . E.4LIS1/G soin lists C1YII1 IIICA110R 1(151551 esa. ..cl.,.e.. T T1 .,M ,.0 i .,.t .«.e.w` '''I'll'' w me with the Realistic® DX-160 Receiver Full- feature designn for granAMisw listening 16995*

The modern world is a "global village" when you own the out" those distant stations. Main tuning control plus pre- versatile DX-I60. Five bands covering 130 kHz to 30 MHz cision bandspread tuning calibrated for the Amateur let you monitor all types of transmissions from all over bands. A product detector and Bß=0 assure superior SSB the world. Pick up all the CB channels, both AM and SSB. and code reception. Controls for audio and RF gain, BFO Hear local programs and news from places like Paris, pitch and antenna trim. Switches for automatic noise London, Cairo, Rome and Moscow. Tune in longwave limiting, AM -to -CW /SSB, Fast or slow automatic volume aviation /marine weather reports and special civil defense control, and standby for use with a transmitter. FET's in all disaster frequencies. Receive WWV time signals and critical stages for maximum sensitivity and selectivity and radio propagation forecasts. And you'll be surprised at crystal- filter IF stages for reduced noise. Illuminated the DX -power you get on the standard AM broadcast S- meter. Headphone jack. And the matching speaker is band. Eleven controls and switches let you really "pull included. U. L. Bisted. The DX -I60-what a way to travel!

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ELEMENTARY ELECTRONICS /September- October 1977 25 www.americanradiohistory.com Where do the pros get their training?

Almost half of the successful TV servicemen have home study training and with them, it's NRI 2 to 1. It's a fact! Among men actually making their living repairing 1V and audio equipment, more have taken training from NRI than any other home study school. More than twice as many! 26 ELEMENTARY ELECTRONICS, September- October 1977 www.americanradiohistory.com A national survey *, performed by an independent research organization, showed that the pros named NRI most often as a recommended school and as the first choice by far among those who had taken home study courses from any school. Why? Perhaps NRI's 62 -year record with over a million students ... the solid training and value built into every NRI 25" Diagonal Color TV... Widest Choice of course ... and the designed -for- And 4- channel Courses and Careers. learning equipment originated Quadraphonic Stereo. NRI doesn't stop with just one by NRI provide the answer. But As a part of NRI's Master course in TV /Audio servicing. send for your free NRI catalog Course in color TV /Audio serv- You cari pick from five differ- and decide for yourself. icing, you build a 25" diagonal ent courses (including an solid state color TV with advanced color course for prac- console cabinet. As you ticing technicians) so you can build it, you perform fit your training to your needs stage -by -stage experi- and your budget. Or, you can ments designed to give go into Computer Technology, you actual bench exper- learning on a real, digital com- ience. And you get a puter you build yourself. Com- Quadraphonic system munications with your own 400 with 4 speakers. NRI's channel digitally- synthesized instru- VHF transceiver. Aircraft or ments are Marine Electronics. CB, Mobile a cut Radio, and more. above the average, Free Catalog... including No Salesman Will Call. a transistor- Send the postage -paid card for ized volt ohm- our free color catalog showing meter, triggered details on all NRI electronics sweep 5" oscilloscope, CMOS courses. Lesson plans, equip- Two Famous Educators... digital frequency counter and NRI and McGraw -Hill. ment, and career opportunities digital integrated circuit color are fully described. Check card NRI is a part of McGraw -Hill, TV pattern generator. They're for information on G.I. benefits. world's largest publishers of top professional quality, designed No obligation, no salesman will educational material. Together, to give you years of reliable serv- call. Mail today and see for they give you the kind of train- ice. You can pay hundreds of yourself why the pros select ing that's geared for success .. . dollars more for a similar course NRI two to one! practical know -how aimed at and not get a nickel's worth giving you a real shot at a better extra in training and equipment. If card is missing, write, c job or a business of your own. You learn at home at your con - lenience, with "bite- size" *Summary of survey results upon request. ?ssons that ease learning and NRI need comprehension. Kits RI SCHOOLS esigned to give you practical McGraw -Hill Continuing Education Center 'nch experience also become 3939 Wisconsin Avenue, 6 -076 st -class professional instru- Washington, D.C. 20016 its you'll use in your work. atyENTARY ELECTRONICS /September -October 1977 29 Acc, Nac1 www.americanradiohistory.com AVANTI® to smaller companies, because the system can be supported from service HIGH bureaus operating the mainframe computer. newscan The new distributed version of PERFORMANCE CADAM, which is available as a commercial product under license from Electronics in the News! Lockheed -Calfiornia, is a complete C.B. ANTENNAS modular software system accurate to six significant digits. Presently being 40 CHANNEL ENGINEERED Computer- Graphics For Rent used by one U.S. company in facilities Lockheed -California Company's high- which are remote from the host com- rASTRO PLANE' speed computer graphics system has puter, the new distributed CADAM remote terminals which offer immediate permits engineering and manufacturing shared without regard CB Base Antenna display, change, and recall of pictures data bases to be and drawings to users in product de- to their geographic separation. Design in thou- Co- inductive sign and manufacturing. Called Com- changes can be incorporated puter- Graphics Augmented Design and sands of drawings overnight. The omni -directional CB sec- antenna that radiates from Manufacturing (CADAM), it is the In advanced applications, one the top - for greáter range first system of its kind with the capa- tion of a complex design can be dis- and performance. 4.46 db played and immediately changed from gain over isotropic - bility of being operated simultaneously stronger signal, clearer from computer terminals anywhere in any of the terminals and composite reception. No coils to drawings can be displayed to present burn or short. Vertical the world. polarity. Patent #3587109 The CADAM system, which has been the total picture. Through interaction Model AV- 101...price $39.95 in commercial use in 12 locations with the computer, animation, rotation= 2.8x more power throughout Europe and the United image- zooming and stacking can be E.R.P. of com- Avanti CB base antennas States for two years as a single cen- achieved to show the operation `rom $20.50 to $404.00 tralized unit, now enables designers and plex designs without production draw- engineers to look instantly at the same ings. The, host computer can then perfor further TM picture from separate locations in order manently store all input RACER 27 to analyze preliminary drawings, detect recall. errors without waiting for printing CB Mobile Antenna drawings and to make necessary design Magnetic mount changes. Dumb is Beautiful The added remote capability of the While the rest of the world concen- Easy to mount on roof or trunk host of trates on so- called "intelligent termi- holes to CADAM system gives rise to a for car, van or truck - no Lear Siegler appears to have drill - fast removal for hide away new applications in small businesses and nals," or car washing. Strong magnet industries. It can be used extensively in taken a step in the other direction by assures position. Mylar pad guards introducing a low -cost terminal -but vehicle finish. only because it's smart to be dumb. Hermi -coil (Hermetically sealed coil) whose -A special molding process Unlike most manufacturers provides a weather -proof coil video terminals have been getting environment. Helps maintain the and more expensive, Lear characteristic antenna impedance, "smarter" even in damp or salt water Siegler has introduced a new 12 -inch, atmosphere. Hermi -coil also helps bare -bones video terminal, which is surface leakage. eliminate internal dumb only in the sense it is a simple Ribbed base - Provides a long leakage path used in high voltage input /output device that the user gets insulators, spark plugs, etc. to tailor to his specific application. Specifications: Electrical Vi wave length The ADM -3LC video terminal offers MHz Unity gain 27 a 960 -character display in 12 V.S.W.R. - 1.3:1 or better standard Coil - shunt fed hermicoil lines of 80 upper and lower -case char- MODEL AV-727 Mobile Antenna System acters. In applications now using tele- cable with with 48" whip, 17' coaxial Each remote CADAM display unit is the ADM -3LC is software magnetic mount. 40 channel $32.95 typewriters, connected to a central computer. Here, the a complete line of high Avanti makes in design of a performance mobile CB antenna systems operator makes changes from $11.95 to $72.50 truck. She uses an electronic pen and a J keyboard, instead of the traditional draftsman's tools, to alter the drawing. electronics, automotive design and manufacturing, general mechanical manufacturing, architecture, engineer- Avanti Research ft Development, Inc. ing, shipbuilding and aerospace. Established 1964 The software program, which is based 340 Stewart Ave., Addison, IL 60101 USA on simple descriptive geometry, oper- It works like a typewriter, which most creators of the ates on standard IBM 360, 370 or people already have been trained at. The famous It makes com- Lear Siegler "dumb" terminal is not so , ©Copyright 1911. equivalent hardware. in most applications Al rights reserved puter -aided design and manufacture dumb, since it works using a common data base accessible at moderate cost. CIRCLE 24 ON READER SERVICE COUPON ELECTRONICS /September- October 1977 30 ELEMENTARY www.americanradiohistory.com "Direct" to you

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The LAB -400 makes studio performance both affordable and convenient. The massive die -cast platter rests directly atop a 16 -pole brushless DC servomotor. Platter and motor rotate at the same speed, 331/3 45 either or Two speeds with Neon light with RPM. No idler wheels, reduction gears or belts to alter the music that's controls for ±4% strobe disc for stored in your record's grooves. The result: wow and flutter is less than pitch adjustment. checking speed. 0.03% WRMS, rumble is better than 63 dB (DIN Bi. Fully automatic tonearm has an effective tonearm length of 811/16", for flawless tracking down to 1/2 gram. Handsome walnut veneer base with ultra- modern, slim design. Elliptical -stylus magnetic cartridge and detachable steel -hinged dust cover significant "extras" that aren't extra. - All for $199.95.* _ow- profile styling with precision shock- mounts to stop acoustic feedback.

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www.americanradiohistory.com duplex. The.transmit and receive speed N EWSCAN is selectable from 75, 110, 150, 300, Digital 600, 1200, 1800, 2400, 9600 to 19200 and hardware compatible, and it can be bauds. Electronics used for direct replacement of the tele- Word format is also tailored to the typewriter. The ADM -3LC is ideal for application with a choice of standard inquiry response applications; in fact, 9, 10, or 11 bit words with odd, even nearly 90 percent of the applications or no parity, plus one or two stop bits. for video terminals require no more Being dumb has other advantages- than a dumb terminal. the ADM -3LC requires almost no The standard 59 -key office -type key- operator training, because it's so easy board, with upper and lower -case shift, to use. It has higher inherent reliability, permits generation of the complete because it takes fewer components to USASCII set. The ADM -3LC displays be dumb. However, hobbyists will have 1 Octal, hexadecimal and binary number systems; representation of nega- upper and lower case in high contrast to wait for surplus units in a few years, tive numbers; binary multiplication characters in a standard 5x7 dot matrix. unless they can afford the $1095 price. and division. Data entry is at the bottom line of 2 OR and AND functions; NOT, exclu- the ADM -3LC screen. Advancing to a Getting Bigger Displays sive-OR, NAND, NOR and exclusive - new line causes the entire data page to The largest liquid crystal display sys- NOR functions; multiple input gates; scroll upward, typewriter style. Full tem ever developed, capable of selec- truth tables; De Morgans Laws; Kar- control of the display is provided by tively displaying more than six -hundred naugh mapping. a display 3 Half and full adders; serial, parallel Clear Screen, Carriage Return, Line alphanumeric symbols, has adders; processors and arithmetic Feed, and Space Bar keys. Backspace area of 0.4 meters (16 inches) by 0.5 logic units (ALUs); multiplication and and character overwrite capability allow meters (20 inches). The successful de- division systems. display editing. End of line is announced velopment of this experimental model 4 Flip flops; shift registers; counters; by an audible tone to alert the operator represents a major step toward the use feedback counters; random access to go to the next line manually. of large -area liquid crystal display sys- memories (RAMS) and read only The ADM -3LC contains both a 20 tems in computer terminals, airport and (ROMs). mA current loop interface and the EIA railway arrival and departure informa- 5 Calculators; keyboards; displays; registers; control unit; program ROM; standard RS232C interface for direct or tion panels, electronic blackboards and address decoding; instruction sets data communication connection to any other educational aids. The result of and decoding; control program. standard computer port. research carried out since 1972, the 6 Central processing unit (CPU); An EIA RS232C extension connec- liquid crystal display system was subsi- memory; character representation; tor, included at no extra charge, per- dized by a grant from the Japanese program storage; address modes; mits easy interfacing with most asyn- Ministry of International Trade and input/output; interrupt priorities; 'programming; assemblers; operating sys- chronous serial printers for hard copy Industry. tems and time sharing. recording of the video display informa- Liquid crystal is an organic com- DWI Compiler Digital Comm.* tion. This bidirectional extension port pound having the fluidity of a liquid, WO, Logic and .. Eknironio may also be used to daisy chain multiple which undergoes a change in transpar- e;rZi. data terminals, or to interface a mag- ency when voltage is applied. This netic recorder for storing larger mes- change in transparency can be clearly 8s sages. seen even in bright daylight. The power Contents include: Binary, octal, and A switch panel next to the keyboard necessary to activate the change is al- decimal number systems; conversion allows operator selection of the ADM - most negligible; only a few microwatts between number systems; AND, OR, 3LC operating mode, either full or half (one microwatt = one -millionth of a NOR and NAND gates and inverters; watt) . Boolean algebra and truth tables; De For this reason, liquid crystal displays Morgans Laws; design of logic circuits have found wide acceptance in devices using NOR gates; R -S and J -K flip flops; binary counters, shift registers such as pocket calculators, wrist watches and half adders. and clocks, in which small display areas are sufficient. SEVEN -DAY MONEY -BACK GUAR- The development of large -area liquid ANTEE: If you are not satisfied with your course, return it within 7 days for crystal display systems had heretofore a full refund. been unsuccessful, primarily because of the long time -lag that occurred between ro: GFN Industries, Inc. EE -9 the application of the voltage and the 6 Commercial St., Hicksville, N.Y. 11801 change in transparency of the liquid Design of Digital Systems crystal material. (6 vols.) $19.88 The Japanese research team over- Digital Computer Logic & Electronics came this obstacle by improving the (4 vols.) $14.88 liquid crystal material, designing new Both courses (10 vols.) $29.90 methods of panel fabrication and driv- Sales tax (N.Y. residents) ing technique, and employing a "dy- Shipping and handling $2.50 per set namic scattering mode." With the dy- Total $ namic scattering mode, the panel indi- a whitening of the The world's largest liquid crystal display cates characters by Name is system is shown in operation at the offices liquid crystal material when voltage applied. Further research is continuing Address of Hitachi, Ltd., one of the three Japanese - based companies who have been engaged toward the simplification of production since 1972 in a joint research project to processes, and application of LSI in the City/State/Zip develop a large -area liquid crystal display. dimming circuit. 32 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com ELECTRONIC TOUCH ORGAN KIT ELECTRONIC Fantastic new design uses CMOS I.C. and a to SWITCH KIT tal of 39 semi -conductors to give a touch con CONDENSER TYPE trol keyboard, all the electronic parts in one PC Touch on Board. This organ is easy to build, yet has fea- Touch Off tures like a full two- octave range touch key- use 7473 I.C. board, variable tremolo; two voices; built -in I.C. and 12V relay amplifier with volume control, complete with $5.50 each speaker and a specially designed plexi -glass case. $1e FM WIRELESS MIC KIT BATTERIES NOT INCLUDED *Ideal beginner f kit for or gift for children á24.50e0. / `y!" Transmit range up to 100 ft. SLIM LINE 41a'ß =.7, Easy to assemble -- (Mic included) CALCULATOR TOGGLE SWITCH $4.50 each 6 Functions with % and memory Half -size of submini toggle switch 8 Digits LED display e. rated 3 amp 125V AC contact Sub -Mini Size One full year guarantee Condenser Microphone 1 10 -99 Special Price Only -9 $2.50 each $8.50 Ea. MS-2432P SPST 0.90 0.80 FET Transistor Built -in ATTERIES NOT INCLUDED MS-244 SPDT 1.00 0.90 MS-245 DPDT 1.20 1.10 SIGMA 7BREI, 12DC RELAY 40042 COIL SPDT CALCULATOR LARGE QUANTITY AVAILABLE FOR OEM with STOPWATCH $1.30 ea. or 10 for $10.00 6 Functions with % and memory ALL BRAND NEW UNITS 8 Digits big green display Built -in X'tal controlled stop TV Games Computer Grade Capacitors watch count to 1/10 of a second. f' 2000 50V 2.00 ea. Special Price Only 111. Fcc 3000 40V 3.25 ea. Spa 8000 55V 3.75 ea. $16.50 Ea. 1000 50V 3.95 ea. BATTERIES NOT INCLUDED Dlr.et t1 I.C. TEST CLIPS S.I.s Only CLOCK KIT Same as the E -Z clips $2950 MOST POPULAR - With 20" Long Leads In Black and Red Colors KIT $1.75 Per Pair Garnes-Tennis, Hockey. Racquet Handball and Single WITHH A NEW CASE l' Handball. L1 Features. 12/24 !-lour Display Avtogovnterdisplavonihesereen. 12V DC REED RELAY SPDT 50/60 HZ Input 6 Digits Readout Kit 7Includes: Grey Color Plastic Case DATRON/ES DIV. SW AUDIO AMP KIT MM5314 Clock Chip PC Boards and Trans PART NO. LH30-029 former, 6 Green Color 0.3" Tube Readouts, Use 2 LM 380 with Volume Control $1.25 ea Power Supply 6 18V DC All other transistor Drivers and other Cor n pDnentS. Multi -Color LED Indicator wily tS.00ea. Special Only $14.95 ea. Red -Green Colors in one LED js- with Plastic Housing TV GAME MODULATOR UNIT WIRE QUARTZ CRYSTALS FCC Approved 1 MHZ $4.95 99e Ea. For channel 3 and 4 WRAPPING ., 2 MHZ $5.25 with occ. 4 MHZ $5.25 Voltage 2V 20 MA per LED Coll TOOL 10 MHZ $5.25 ONLY $4.50 Battery 3.579 MHZ $1.25 TIMER KIT $33.50 nitre Color TV Tyne Time Controlled from 1.100see. Wire Wrapping emee TI 1955 tad Ideal to be used as time delay Alternative ÁY38500 -1 Wire in Bulk SAE DIP SWITCHES unit for burglar alarm, photo e Geme (28 Pin Dip) Red or Black coNlterE wm I Rr service, and other purposes. TV Game Chi p with Data AND 4IfVl Max. loading 110V, 2 AMP. Tennis Squash hockey. Supply voltage 12.18V D.C. practice & 2 shooting. Special Only $11.0. MATCHED PAIR P.rr Nu 1004692 4. ,PST SW eTian ELECTRONIC IC TIMER $11.50 each POWER TRANSISTORS MOTOROLA M2E2955 PNP 100869ZCrSPST SW MJE3065 NPN 4 ,OST hey on a Mrn pir NI -CD 10 AMP 60 VOLT 90 WATTS tn,l. Electronic Police Sien Kit S t 50 e RECHARGEABLE i $2.25 PER PAIR e.. a60P Ideal for use as an alarm .. 52 60 ea unit. High output up to 5 BATTERIES watt at 12V DC supply. AA SIZE, 12v $1.25 ea. Sub Mini Size SUBMINIATURES TOGGLE Can be used with horn - CSIZE,12V $1.50 ea. V 'PANEL METER 7 type speaker. $14.00 SWITCHES each SUB C SIZE ea. 500 UA SPDT ea POLiCE AL ARNE uNIT $1.50 On OH sí30 F SIZE,1.2V $2.50 ea. ONLY $1.20 ea DPDT On Off a1...50 - -ÿr1 3POT On s1.75 ea. Music on Light COLOR ORGAN KIT Min Sir. Rocker TYeu AUTO ALARM KIT AC POWER SUPPLY Also Available at the some Pnce in Colour u IU Operates in low voltage 19 V- C, Irin lighter Auto Adapter Typo Transrormar 24V Can 12V AC 200 MA Output DCI. control up to Alarm IS an me. QUAD VOLUME CONTROL 100 low voltage light bulbs. sell rolled auto pro $2,75 Each Light bulbs change colors to ..$rani system, normally the tones of music. Connect within the glove hoe ot Jrl mobile Melts Alan.. CI.ak to the speaker output of the nel M a I o °k ° k c T701E. 60He. 12 hr Portional to the angle o turning oft the $ ignition. amplifier. .r LT7010. 60Hr, 2. hr. aisoley Perfect $10.50 the alarm automatically sell COLOR UNIT per kit turns Power Supply 12v AC When the auto entered, the, horn will ideal for panel clock, oink clock, 11101V $7.50 ^a,.rró and alter a 1045 second entry delay. The o auto Don't move ! LIGHT CONTROL automobile owner, by serti0* the roo,rron key, will activate.$ he alarm. Once activated, PUSH- SUTTON SWITCH the will sound for two minutes before SWITCH KIT alarm N /Open Contact autmatically turning oil. The alarm then re 500 UA Color: Red, White, Blue, Can control TV, radio, lights sets and rs ready to again protect Ihn vehicle VU METER or can be used with the Police from unwanted envy 3reen, Black. 4/$1.00 Special Price N /Close Siren Kit to form a burglar FEATURES Simple installation 5 wires also alarm system. Automatically turns o when a is parked, 2 for $1.99 Available 500 ea. $4.50 each Adjustable entry tie. Extended r exit time to LARGE QTY. AVAILABLE allow for u ushed wart from vehicle. Numer- SO UA PANEL METER applications include protection of boats. SOLID STATE ELECTRONIC loi BUZZER campers, trailers, motorcycles, trucks, Cannot Size 1 '.3 4 ".3 4 POWER r `SCared'l n. O,ErtO SUPPLY KIT be deactivated by "hot w ing" an auto, Can- but can be easan Supply voltage r. 5V 1- not anti 0 -35V D.C. REGULATED be turned oil withoutt ignition key, Neg- Own scale out on Ton SPood Ideal for Alarm Uses UA723 and ZN3055 Pow,: ative ground only new of Tone Indicator PER Only $3.80 ea. TR output can be adjusted 1,0n, ONLY $10.00 KIT $1.50 NM or 2/$2.50 0 -35V, 2 AMP. Complete with PC board and all electronic parts. $9.50 each MINIMUM ORDER $10.00. Californid residents add 6% wee tee. 8/77 All orders add 10% postepe for out of state. Overseas countries odd 15% of total order tOr notzage MA1003, 12V DC CLOCK MODULE SEND CHECK OR MONEY ORDER 1-0 Built in X'TAL controlled time base. Protected against INTERNATIONAL INC. automotive volt transients. 12603 CRENSHAW BOULEVARD HAWTHORNE. CALIFORNIA 90250 C9 dFORMULA1` Automatic brightness con- For more information please call (213) 6795162 trol with 0.3" green color STORE HOURS 767 Monday - Saturday 9AIIRAMERIGRE display. Display turnoff $23.50 EACH with ignition "OFF ". a

CIRCLE 30 ON READER SERVICE COUPON ELEMENTARY ELECTRONICS /September- October 1977 33

www.americanradiohistory.com for the Experimenter! INTERNATIONAL CRYSTALS and KITS

.O2° Calibration Tolerance EXPERIMENTER CRYSTALS $325 (HC 6/U Holder)

-1 $425 The OF oscillator is a resistor /capacitor circuit Cat. No. Specifications providing oscillation over a range of frequen- 031300 3 to 20 MHz - For use in OF -1L OSC Beep the Metal Dish cies by inserting the desired crystal. Specify when ordering. 2 to 22 MHz, OF-1 LO, Cat. No. 035108. 18 to 60 MHz, 031310 20 to 60 MHz - For use in OF -1H OSC My husband says that you cannot use a -1 HI, No. when ordering. OF Cat, 035109. Specify when ordering. Specify metal dish in a radar oven. 1 do, and it works OK. Where do people get the idea Enclose payment with order (no C.O D.I. Shipping that you can't use metal dishes? MXX -1 Translator RF Mixer and postage (inside U.S.. Canada and Mexico only) -Y. G., Bronx, NY 3 to 20 MHz, Cat. No. 035105 will be prepaid by International. Prices quoted for 20 to 170 MHz, Cat. No. 035106 $4.50 ea. U S.. Canada and Mexico orders only Onlers for shipment to other countries will be quoted on re- -1 dishes reflect radar waves without SAX Transistor RF Amp quest Price subleçt to change. Address orders to Metal 3 to 20 MHz, Cat. No. 035102 converting any of them to heat. Radar 20 to 170 MHz Cat. No. 035103 $4.50 ea. M/S Dept.. PO. Box 32497 Oklahoma City. Oklahoma 73132 BAX-1 Broadband Amp waves bounce from all directions inside 20 Hz to 150 MHz Cat. No. 035107 $4.75 ea. WRITE FOR BROCHURE the oven cavity and through the food. A glass shelf, which freely passes radar waves, supports the food above the bottom International Crystal Mfg. Co., Inc. of the oven, thus waves enter the food 10 North Lee Oklahoma City. Oklahoma 73102 from below. Prevent the radar waves from entering the food from the bottom, and you have reduced the efficiency of your CIRCLE 9 ON READER SERVICE COUPON oven 25 -50%. By the way, let's call it a microwave oven and microwaves, and leave FRIENDS radar to the navigators. No, you will not FRIENDS DON'T LET damage your microwave oven with the .aUA,ESo..Y DRIVE DRUNK. metal dish, but since it must run for a long time for each meal, the overall effective life of the unit is reduced and electricity bills increase. 'WIItH 'WI N! O,r,,,r,Nr OrT1,brORT,nOM. N,MM,1. NIONMAY nArnc UM, ADNIMnO,tqN

Long Life to You Hank, I predict Citizens Band radio GET CABINET, TERMINALS AND STRIPPER -CRIMPER will die. What I mean is that interest in the ALL FOR LESS THAN VALUE OF TERMINALS! band will diminish and instead of 10,000,000 CBers, we'll have 100,000 or so. What do you thnk? *240 of the most used, -F. Y., Drain, OR insulated, "color- coded," solderless terminals I'll believe it when they take the squelch *Heavy-duty, 25 drawer, control out of the CB transceiver. We are steel cabinet entering an era of personalized two -way radio communications which will be as (91/2" H x 12" W x 51/2 D) big as the land -line telephone. Both com- *Finest quality combination munication forms will be with us for a wire stripper and crimping long, long time, until someone develops tool, $5.85 value included ESP with a private channel for everyone. A terrific selection of the most used, insulated, color coded, Radio Contact crimpable, solderless terminals. What is the best time to pick up Radio That's right! You get terminals, Nigeria? My son is working there for the cabinet PLUS stripper- crimper ($5.85 value)...All for less than next year. -D. I., Cumberland, OH (wt) PIECES Plus $300 the normal retail price of the shipping and terminals alone. Unconditional RING TYPE handling money -back guarantee. Tool The best time for picking up Radio Ni- 9 SIZES 90 and terminals 1st quality geria is around 0430 -0455 GMT. At 0455 American made. GMT, they sign off. Look for them on FORK TONGUE 7255 kHz in the 41 -meter band. No, I 8 SIZES 80 30 DAY MONEY BACK GUARANTEE didn't hear Radio Nigeria! A local SWLer 0:135',) BUTT -SPLICES QUALITY TERMINALS, DEPT. EE7 filled me in. Listening to broadcasts from 3 SIZES 30 368 Hillside Ave., Needham, Ma. 02192 your son's part of the world will make EJ Check or money order enclosed for letter writing easier and more interesting. QUICK DISCONNECT $24.95 plus $3.00 shipping & handling 1 MALE - 3 FEMALE SIZES 40 Mass. Residents add $1.25 Sales Tax Playing With Matches TOTAL NAME What is the difference between an an- NO OF PIECE' 240 box a base station i ADDRESS tenna match made for and one made for an automobile? QUALITY TERMINALS CITY -R. T., Pine Bush, NY 368 Hillside Ave., Needham, Ma. 02192 ZIP Residents add $1.25 Sales Tax STATE Mass. L J There should be none provided they are 34 CIRCLE 35 ON READER SERVICE COUPON ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com both rated for the same power. Base units fying glass attached to your glasses or are made fancier, some are made with one that comes on a headband. Be sure desk -top finishings, etc. Hams should not to rush, your fingers can't move as fast The Allmeric,n watch maximum ratings carefully. CBers as your eyes. need not. Just about every match box Wide FLeceivep made can handle the power. The Folks Don't Like It Fix the Trouble I have terrible TVI from my CB rig. 1 Would a shortwave radio receive CB tried filters on the output, including a signals better than a CB could? My rig dummy load -no help! What can 1 do? gets a lot of cross-channel and sideband -E. B., Kearny, NJ interference. -J. T., Montreal, Canada Try an AC line filter. You may be pumping RF into the AC line. Also, By cross-channel, I assume you mean ground the case of the CB rig to a good DRAKE SPR -4 adjacent channel reception. If this were electrical ground. And, if you changed the Short Wave Receiver the case, the receiver section of your CB microphone, go back to the original -you Direct Frequency Dialing *All Solid State is out of alignment. Most modern day CB never can tell! Programmable Coverage FET Circuitry rigs have an adjacent channel rejection of 45 dB. I don't know whether your A general purpose receiver, the SPR -4 may short- Simple -Syn Erratta. A few errors be programmed to suit any interest: SWL. wave receiver can do better. As for SSB crept into last issue's schematic diagram Amateur, Laboratory, Broadcast, Marine interference, if it's on your channel, your Radio, etc. Freq. Coverage: 150 -500 KHz of our Simple -Syn plus any (23) 500 KHz ranges, .500 to 30 MHz rig, or any other receiver cannot elimi- Music Machine. Please make the following nate the trouble. I'd suggest you have a corrections: FEATURES: Linear dial with 1 KHz read- pro tune C8 is shown with reversed polarity. out 4 -pole crystal filter in first IF -up the receiver section of your 4 -pole LC filter in second IF Three CB rig and check out the antenna system Be certain the negative side goes to bandwidths: 0.4 KHz, 2.4 KHz, and 4.8 KHz carefully. ground. for: CW, SSB, AM Superior cross - modulation and overload performance R4 is mistakenly shown on the sche- Power: 120 VAC, 220 VAC, or 12 VDC Old and Delicate matic as 3.3K but it should be 330K Crystals supplied for LW, BC and seven SW I am restoring a pre -WW portable re- bands Built -in speaker Notch Filter. (330,000). R5 is shown as 1200, but ACCESSORIES: 100 KHz calibrator, noise ceiver and I can't find a 1F3. What can I should be 12,000. R10 is shown as blanker, DC power cord, loop antenna, crys- do? tals for other ranges. 220K, but should be 270K (270,000). -F. S., Fargo, ND All the values are correct as listed For complete in details contact: DRAKE The vacuum the parts list, only wrong in the sche- 1F3 tube can be replaced R. L. DRAKE COMPANY by the 1T4 type. I owned an old Philco matic. portable using tubes of this type 540 Richard St., Miamisburg, Ohio 45342, and they Phone: (513) 866 -2421 Telex: 288 -017 popped everytime I pulled a tube from the Lend A Hand set and replaced it. Be sure the battery Here are the requests from a few read- CIRCLE 28 ON READER SERVICE COUPON supply is disconnected and the electrolytic ers. If you can assist, please write directly capacitors are discharged before removing to the person in need, do not send to me. and replacing tubes. Sending help via my office will only delay the mail. Armchair Copy Bigger Spread A C. A. D'Andrea needs service and in- Hank, is it true that Cadmium Sulfide structional manual for the Lafayette Radio photocells see better than the human eye? TE -19CRT rejuvenator- tester, Knight My teacher says so, and I think he is 83Y145J RF generator, and Knight wrong. 834135J signal tracer. Send whatever you -D. G., Boulder, CO have to 414 West 35th Street, Lorain, OH 44055. The human eye has an approximate A Schematic diagram and info on a - range five of 500 to 600 microns for the wave- inch reel -to -reel Shinagawa SSS -501 tape length of light it sees. The cadmium sul- recorder is needed by George Poitras, 91 fide uses about 500 to 700 microns. So you Boucher St., Edmundston, N.B., Canada see, your teacher is correct, provided you E3V -1P8. are talking about the light spectrum. A If you know Basic, can you tell Carl Rosen how to plot points on a graph, Shortwave Listening Too Many Thumbs while following an equation. It's a Hewlett - Our ONLY occupation is Every time 1 have to replace a phone Packard computer. Write to Carl at 174 -A cartridge, I am all thumbs. 1 break leads, Boney La., Nissequoque, NY 11780. supplying everything you lose screws and spacers, etc.; it's a disas- A Paul Crowson, 529 Witsell Rd., Jackson, need to tune the mediumwave ter! Why don't they make snap -in units for Miss. 39206 would like to get the manuals and shortwave bands -and guys like me? and schematic diagram of a Philco Model identify what you hear. Our -M. P., Gillette, WY 60 cathedral radio and a Zenith Model NEW mini -catalog details 10Aí- radio /phono. Barlow Wadley, Drake and They do make snap -in units, but only A Dr. S. G. Hueston, 97 Edward St., Yaesu receivers, WORLD on cheaper cartridge models. Weight is London, Ont., Canada N6C -3H6 would RADIO TV HANDBOOK, logs, very important, the lighter the mass on the like to have the schematic diagram and receiving antennas & tuners, tonearm, the better is the sound reproduc- operating manual for Signal Corp. receiver calibrators, FM or TV guides, tion. Thus, convenient mounting systems R274 -FRR made by Hallicrafters. AM pattern maps, QSL which are heavy cannot be used. But that albums, ITU Got a question or a problem with a project -ask publications, doesn't help you. Do what I do, when in- Hank! Please remember that Hank's column is RTTY displays, CONFIDEN- stalling a phono limited to answering specific electronic project cartridge. When inserting questions that you send to him. Personal replies TIAL FREQUENCY LIST, screws, put a bit of bees wax on the screw- cannot be made. Sorry, he isn't offering a circuit clocks and all SWL books. driver blade so that the screw will afix to design service. Write to: it. It helps to hold it, and the bees wax is Hank Scott, Workshop Editor GILFER ASSOCIATES, INC non -corrosive. Also, use tweezers to handle ELEMENTARY ELECTRONICS the delicate clips and fine wire that attach 229 Park Avenue South P.O. Box 239, Park Ridge, NJ 07656 New York, N.Y. 10003 to the phono cartridge. And use a magni- /lßl,.llll ,lll t ,Il 1. 1,.1w111.J Iß..1,,1u111..11ß-.t..l Ill.. ELEMENTARY ELECTRONICS /September- October 1977 35 www.americanradiohistory.com The better the training

Sendfor the better you'l REE ú i ated IN- CIRCUIT TRANSISTOR TESTER career TROUBLESHOOTER guide COMPU- TRAINER VOM

s tóletroE

SOLID -STATE i OSCILLOSCOPE

NTS /HEATH GR2000 Digital Solid -State Color TV 315 sq. in. Picture

(Simulated TV Reception) ELECTRO -LAB

As an NTS student you'll acquire the know -how that This electronic gear is not only designed for train- comes with first -hand training on NTS professional ing; it's field -type - like you'll meet on the job, or equipment. Equipment you'll build and keep. Our when you're making service calls. And with NTS courses include equipment like the NTS /Heath easy -to -read, profusely illustrated lessons you learn Digital GR -2000 Solid State color TV with first -ever the theory behind these tools of the trade. tuning; digital features like silent varactor diode Choose from 12 NTS courses covering a wide range and channel selection, (with optional digital clock), of fields in electronics, each complete with equip- big 315 sq. in. ultra -rectangular screen. ment, lessons, and manuals to make your training more practical and interesting. Also pictured above are other units - 5" solid state oscilloscope, vector monitor scope, solid -state ster- Compare our training; compare our lower tuition. eo AM -FM receiver with twin speakers, digital multi - We employ no salesmen, pay no commissions. You meter, and more. It's the kind of better equipment receive all home -study information by mail only. that gets you better equipped for the electronics All Kits, lessons, and experiments are described in industry. full color. Most liberal refund policy and cancella- 36 ELEMENTARY ELECTRONICS /September- October 1977

www.americanradiohistory.com and the equipment be equipped.

HIGH FIDELITY SPEAKERS

SOLID -STATE STEREO AM /FM /MULTIPLEX RECEIVER

CO:OR BAR /DOT GENERATOR

]

TUBE & TRANSISTOR TESTER F ET -VOM AM /FM /SW PORTABLE SOLID -STATE RECEIVER

74 sq. in. VECTOR MONITOR Solid -State SCOPE B &W TV

..mil:. 3 lt..:.

SIGNAL GENERATOR DIGITAL 5" OSCILLOSCOPE SOLID -STATE 2 -METER FM MULTIMETER SOL D -STATE TRANSCEIVER & POWER SUPPLY POCKET RADIO tion privileges spelled out. Make your own com- parisons, your own decision. 'NATIONAL TECHNICAL SCHOOLS Dpa 222. Mail card today, or 4000 South Figueroa St., Los Angeles Calif. 90037 - clip coupon if card is missing. Please send FREE Colo., Catalog and Sample Lesson. NO OBLIGATION. ND SALESMAN WILL CALL. Colar TV Servicing Electronics Technology NO OBLIGATION. NO SALESMAN WILL CALL B & W TV and Radio Servicing Comduter Electronics 1 EIe.Nronic Communi:a:ions Basic Electronics APPROVED FOR VETERAN TRAINING FCC License COL rse Audio Electronics Servicing Get facts on new 2 -year extension 1 NAME. AGE

ADDRESS_ _. APT tt TECHNICAL NATIONAL SCHOOLS CITY__ STATE TECHNICAL -TRADE TRAINING SINCE 1905 Please fill in Zip Code for fast service Resident and Home -Study Schools ! Check if interested in G.I. Bir information. 4000 So. Figueroa St., Los Angeles, Calif. 90037 El Check if interested ONLY in classroom training in Los Angeles - Its - EMI t - S = JI ELEMENTARY ELECTRONICS /September- October 1977 39 www.americanradiohistory.com CSC's done it again. life, the entiredisplay flashes at a for use in lab or field. Internal alkaline Broken the price and perfor- 1 Hz rate. or Ni Cad batteries. 110 or 220V with mance barriers with new MAX -100. MAXimum versatility. MAX can charger /eliminator. 12V with auto- The multimode, professional porta- be used with clip -lead cable sup- mobile cigarette -lighter adapter/ ble frequency counter that gives you plied. Mini -whip antenna. Or low -loss charger. And external 7.2 -10V power more range, visibility, accuracy and in -line tap with UHF connectors. For supply. versatility than any comparable unit AM or FM; CB, ham, business radio MAXimum value. Accurate at anywhere near its low, low price. and R/C transmitter or receiver align- enough for laboratory or field- service MAXimum performance. ment. Monitoring audio and RF gen applications, MAX is surprisingly MAX -100 gives you continuous erators. Checking computer clocks economical. At S134.95* complete readings from 20Hz to a guaranteed and other digital circuits. Repair of with clip -lead cable, it's priced low 100MHz, with 8 -digit accuracy. Fast depth sounders and fish spotters. enough for educational or hobbyist readings with 1/6-sec. update and Troubleshooting ultrasonic remote use.

1 -sec. sampling rate. Precise readings, controls. And hundreds of other ap- For more information, see your derived from a crystal -controlled plications. CSC dealer or contact us directly. time base with 3ppm accuracy. High - MAXimum visibility. MAX -1100 sensitivity readings from signals as features a big, bright 0.6" multiplexed CONTINENTAL SPECIALTIES CORPORATION low as 30mV, with diode overload 8 -digit LED display, with leading - protection up to 200V peaks. zero blanking. So you don't have to Input signals over 100MHz auto- squint, or work up close. And, MAX's flash the most flip -up stand is -in. matically significant built 44 Kendall Street, Box 1942. New Haven.G CT 06509 digit. And to indicate low- battery con- MAXimum flexibility. MAX -100 203 -624 -3103 TWX 710-465-1227 West Coast 351 California St.. San Francisco. CA 94104 dition and extend remaining battery operates from four power sources, 415-421-8872 TWX 910-372-7992

SPECIFICATIONS FOR MAX -100

Frequency Characteristics Ranee: 70 Hz to 100 MHz (guaranteed): 110 sixth and seventh digit when input frequency exceeds 1 MHz. Overflow:

MHz typical. Gaiety; 1 sec. providing 1 Hz resolution throughout freq. When input signal exceeds 99,999,999 Hz, the most significant (left hand) ± range. Accuracy; 1 count -- Time Base error. digit flashes, allowing user to read in excess of 100 MHz. Display update: Fixed 1/6-second plus 1 second gate time. Low Battery Indicator: When

Input Characteristics impedance: 1 M(1 shunted by 56 pf. Connector: phone batteries or power supply falls below 6.6 VDC, all eight display digits flash jack.Çouotin: AC Sine Wave Sensitivity: 30 mVRMS; 10 Hz -50 MHz; 100 at a one -Hz /second rate. During battery operation, flashing display extends mVRMS, 50 MHz to 80 MHz; 300 mVRMS, 80 MHz and above. Maximum operating time of unit. Input: 200 V Peak, 20 MHz- 500Hz; 100 V Peak, 500 Hz -1 KHz, 75 V GENERAL Power Requirements: 6 AA Alkaline or NiCad batteries (internal Peak, 1 KHz -10 MHz; 50 V Peak, 10 MHz and above. battery compartment; External: 110 -220/AC Battery Eliminator charger; Internal Time Base Characteristics Freauencv 3.579545 MHz crystal Automobile cigarette lighter adapter for both charging and operating: 7.2 to oscillator. Setability: ± 3 ppm @ 25 °C. Trimmer Adjustment - 4 ppm. 10 VDC external power supply; Battery Life: Alkaline, 3 hrs., Cont. use; Temperature Stability: Better than 0.2 ppm / °C, 0 to 50° C. Maximum Anina 8 hrs. intermittent use. NiCad, 3 hrs., Cont. use, 6 hrs. intermittent use. Rate: 10 ppm /year. Battery Charging: 12 -14 hours required for full charge. Size (HWD): 1.75" x 5.63" x 7.75" (4.45 x 14.30 x 19.69 cm). Weiaht Less than 1.5 lb. Display Characteristics Display: Eight .6" high LED digits, with anti -glare (0.68 kg) with batteries. Accessories Included: 100 -IPC clip -lead input window. Lead -zero blanking: decimal point automatically appears between cable; detailed applications /instruction manual. FREQ. OU i

'Manufacturer's suggested retail CIRCLE 29 ON READER SERVICE COUPON 40 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com elementary Se19.7Oct. Electronics

PHONE 1H11

How to link your borne to today's new, computerized nerve- centers.

by Herb and Lawrence Friedman

EVEN IF YOU NOW haven't the vaguest pany charges you for the privilege of to communicate with computers. Since interest in personal computers, with- having a telephone. the average reader will have access to in a year or two you will likely be Whether you opt for a personal a time -share dial -up computer, (via the up to your neck in personal computing computer in your own home, or a con- telephone) or a personal computer in whether you like it or not; and by nection through your telephone to a the home, we are going to cover only personal computers we don't mean a time -share computer service you are the terminals that work with both sys- Hewlett- Packard or TI programmable going to need a terminal, the device tems. There is no reason to spend sev- calculator- though they are, in fact, that lets you communicate with the eral hundred dollars for a terminal personal computers. computer. that works with a personal computer Personal computer means a full Trouble is, the surplus market is only to find that if someone offers you blown computer you can use to keep loaded with computer terminals that are free time on a giant time -share system and process business and family rec- really worthless for general use, so this your terminal can't be used ords; one your children can, and prob- article is going to serve as both an in- Two Piece Terminals. At the very ably will, use for their math, science troduction to computer terminals and minimum a computer terminal consists and social studies -at all levels from a guide as to what's available arid of two separate devices: a typewriter grade school up; a computer your pre- really worthwhile. style keyboard that transmits informa- school children might use to play games Because of space limitations we can- tion to the computer, and a display de- such as Star Trek and Klingon Capture; lot cover every type of terminal used vice that "prints" the information com- a computer you could use for adult ing from the computer. The display can education courses taken in the comfort either be some form of printer that of your own home. "types" a written record -called "hard For less than the cost of a decent copy" -on paper; or a CRT, which can hi -fi system, or a console color TV with be a TV monitor, a modified TV re- remote control, you can have a corn - ceiver, or anything else using a CART. puter in your own home as powerful as As a general rule the two sections - some of the big IBM jobbies, and the keyboard and printer -are totally inde- whole computer won't take up much pendent even though you might have more space than a couple of shoe - used, or observed, a working computer boxes. If you don't have room for and seen that whatever was typed on two shoeboxes worth of electronic the keyboard was printed out on the hardware you can rent computer time display. The keyboard transmits infor- from regional and national companies. mation to the computer, which then For example, did you ever wish you echoes back to the display so the user had an hour or so of computer time By simply feeding punched tape through can check the entry. If the user types the reader, as shown, a computer will to finish a school problem? Call Data the word ready the computer echoes accept a program at the maximum TTY back the word and the display shows will charge you as low as $6 per hour speed of 110 words per minute. This the word ready. Without the echo the (educational rate) for using their com- particular program will require a full puter. If all you need is a couple of thirty minutes of computer time and will user would have no idea whether he hours on their computer per month the check every single bit of memory tin an was transmitting correct data into the bill could be less than your phone corn- 8K word memory board. computer. The condition of separate

ELEMENTARY ELECTRONICS/September-October 1977 41 www.americanradiohistory.com @/@ PHONING THE FUTURE

ISTARrI I 3 4 5 1 6 7 8 STOP STOP! keyboard and display is termed full- 2 duplex, meaning two things can occur ASCII MARK at the same time -you can transmit and CHARACTER LEVEL 8 receive simultaneously. SPACE LEVEL Another condition is termed half - duplex, and there appears TELETYPE TRANSMISSION. to be several MARK LEVEL IS 20 M A. versions of what is meant, by half - SPACE IS OPEN CIRCUIT. 110 BAUD duplex. The most common use feeds the keyboard character to the display SPACE and the computer. When the computer ASCII MARK echoes back, the display shows both the CHARACTER original keyboard entry and the echo. In ., RS 232 ELECTRICAL TRANSMISSION IS GENERALLY INVERTED SO MARK full -duplex, a keyboard entry of ABCD IS 0 (REFERENCE) AND SPACE IS is displayed via the echo as ABCD. In POSITIVE. 300 BAUD half -duplex the display shows AABB CCDD. In full -duplex the word ready is displayed as READY; in half-duplex it appears as RREEAADDYY Half - duplex transmission is commonly used when time cannot be allowed for the RS232 ASCII CHARACTER "0" computer to echo back. There are cer- 300 BAUD tain conditions when this is necessary, and the half -duplex mode, at the least, All time -share and most of the On to the next confusion. The 8- allows the user to check spelling and larger personal computers use an level ASCII character code really codes as they are entered into the electrical character code termed uses only seven bits to transmit the computer. ASCII, short for American Standard character; the eighth bit is for some- Local is a term meaning the key- for Communications Interchange of thing termed parity, and even here board is connected directly to the print- Information, and pronounced "as- we don't stop because there must be er so that keyboard entries are fed key." signals to synchronize the sending only to the display and any recording The 8 -level ASCII code presently in and receiving equipment. After all, device attached to the display. In this use was designed for teletype so the something has to tell the printer that manner a tape can be prepared for associated terminology refers to TTY the electrical pulses to follow are a transmission to the computer at a later operation even if the entire communi- character and not line noises. So we time. cations system is electronic with a add a start bit in front of the charac- If the terminal is in the vicinity of CRT for the display. ter. Now we must turn off the printer a computer it can be connected directly The TTY terminology in turn goes so it doesn't generate "garbage" to the computer via multiple wires -this back to the days of the telegraph sensing line noises as character bits. is termed hard wired. On the other when one or a series of magnetic For this we follow the parity, or hand, it is possible to use the telephone sounders was connected in a battery eighth bit, with two stop bits. Now to "converse" with a computer on the powered loop through the telegraph we have a total of 11 -bits making up other end of town, or even the country. keys. Since everything was in series, the 8 -level ASCII TTY character, as The terminal is connected to a device the normal off condition was for cur- shown in our earlier diagram. called a modem, an acronym for Mod- rent to flow in the loop and this con- Note that each bit is 9.09 msec ulator- Demodulator. Some modems can dition was called mark. When the wide, making a total character length be hard wired directly to the telephone key was open to send a character of 100 msec. The start bit turns on line; others can be acoustically coupled the current loop was broken, the the printer, the first seven bits rep- by simply placing the telephone's hand- sounders made a "click" and the resent the character -either letter, set into a built -in receptacle. The open current loop condition was numeral, control function, etc. -and modem takes the signal from the key- called space. We still use the terms the stop bits insure the printer stops board and converts it into audio tones mark and space today. When a corn - and resets for the next character. which are fed to the computer through puter's TTY is connected to its as- The parity, or eighth bit, is used to the telephone line. At the receiving end, sociated equipment and it is not "test" the transmission when there is a different type of modem converts the receiving a character signal it is fed the possibility noise can obliterate, audio tones back to an electrical signal 20 mA of current for the printer -the or add, a bit. The keyboard can be for the computer. Each modem is a mark condition. To send characters programmed so the parity bit is two -way device. The modem at the the current is interrupted -the space added to provide odd or even parity; computer takes the computer's output condition. (You might have to read that is, the total number of character electrical signal and converts it into this over a few times to get the sense bits from one to eight is even or odd. audio tones for transmission to the ter- because it appears to be the oppo- Assume the keyboard is pro- minal. At the terminal the modem con- site of what's needed. As we'll show, grammed for even parity and the let- verts the audio tones back into electrical in electronic systems we invert the ter Q is transmitted. The letter Q uses signals needed to drive (produce) the signal so mark is generally zero cur- three bits- Numbers 1, 5 and 7. Three display. To avoid a mix -up on the rent or voltage and space is some is an odd number so the eighth bit telephone line the audio tones from the amount of current or voltage.) is automatically added, making the

42 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com terminal are at a different frequency than those from the computer. 8 LEVEL ASCII CHARACTER The basic input /output device for both time -share and most personal computer systems is the model 33 tele- START BIT BIT BIT BIT BIT BIT BIT PARITY STOP STOP BIT 2 3 4 5 6 7 BIT 8 BIT BIT type, and the terminology for the model 33 has become, more or less, the ac- 9.099.09 cepted terminology for all I /Os. A MS. MS. model 33 printer (no keyboard) is 110 BAUD TTY CHARACTER, IOOMS. 4.1 called an RO for Read Only. CRT displays, or any other type of printer without an associated keyboard are waveform with the bits positive -going. I~ 8 LEVEL ASCII -el usually termed ROs. (Yes, RS -232 provides for a negative - S A model 33 teletype which consists T S 7 T going waveform resembling the TTY A 2 3 4 5 6 8 of a printer and keyboard is termed a R D waveform shown in the topmost fig- P KSR for Keyboard Send and Receive. T ure). Note that RS character the -232 Any other type of TTY or CRT ter- shown is 300 baud sothe second I k-3.3 MS. minals with a keyboard and display is stop bit is eliminated. termed a KSR. 300 BAUD In both the top and middle figures CHARACTER, 33MS, Then there is ASR for Automatic 1 is bit number not used so the start Send and Receive. This is a model 33 bit stands alone. The bottom figure TTY with an attached paper tape punch when bit 1 is shows what occurs and a reader to read back the paper total number of bits transmittted four, part of the character. The letter tape. The tape can be punched either an even number. At the receiving end "U" has alternating bits starting from the keyboard in the local operat- only the first seven bits are pro- at bit 1, so bit 1 combines with ing mode, or by the computer via the cessed, the Q. A the to form a giving character start bit "pulse" dou- echo. The punch is mechanically at- parity detector, however, counts all ble the reference bit length of 3.3 tached to the printer so whatever the the bits; if It's not an even result the msec. The receiving device senses printer receives (with some exceptions an the printer might indicate incorrect leading edge of the start bit, programmed through a "stunt box ") character has been received, or the times out for 3.3 msec. and since it gets punched out on the tape. The parity detector might light a lamp or "sees" a signal at the start of the reader feeds out as does the keyboard. sound a to indicate is bell something next 3.3 msec. interval it "counts" If the tape is played (or read) by the wrong with the transmission. If the 1. bit It is through the timing that the reader, the output from the TTY is character originally had an even num- receiver bits. For counts example, just as if it was sent from the key - ber of bits, such as the letter V which in the top figure bits 4, 5 and 6 run hoard. Both the punch and reader can uses bits Numbers 2, 3, 5 and 7, the together and "appear" as part of a be controlled from the computer by eighth parity bit is not added since square waveform. In actual fact the special signals, hence, this type of TTY the transmission has an even num- TTY doesn't recognize a square is termed Automatic Send and Receive, ber bits for and of the character, the wave; its timing mechanism simply or ASR Any similar terminal device is parity detector "sees" an even count. counts three contiguous bits followed known as an ASR. Both the keyboard and parity detec- by a space. Though the model 33 TTY, and its be tor can programmed for even or In both TTY, modem, and most designations such as RO and KRS, is odd parity. Where there is a direct personal computer use each ASCII the common standard of reference for connection to the computer, or a character is transmitted serially, most hobby and time -share computer circuit with little likelihood of noise, meaning one bit follows the other. systems there are other keyboard -printer the parity detector is usually disabled There are special circuits, however, devices that provide similar functions. or simply not used. that require a parallel transmission, Other straight TTY equipments are Though a TTY requires a bit length that is, all bits are transmitted available as ASR and KSR equivalents of 9.09 msec. the resultant 110 words through at least seven wires at the of the model 33; and there are special per minute printer speed is too slow same time (eight wires if parity is line printers that print an entire line for most users. 300 WPM is the stand- used). This is generally done elec- of copy at high speed, in contrast to ard for electronic terminals used by tronically with each bit represented the TTY's one -letter -at -a -time printout. time -share (with echo) and personal by a high (logic 1). Smart and Dumb. Another variation We computers. get the higher speed The subject of the ASCII code and is the "dumb" CRT terminal. This is a by simply reducing the time of each its transmission is rather extensive. keyboard and CRT display made to bit to 3.3 msec., and by eliminating We have featured the general high- function exactly as a KSR TTY. the second stop bit. lights you'll need to know as you get Though all- electronic, it puts out exactly The actual TTY transmission of the started in using computers. A more the same type of signal as a TTY and No. 8 is shown in the topmost figure. complete explanation geared for responds to the same input signal, print- Note that the reference is mark, and hobbyist use can be found in the ing one letter at a time at TTY speed the transmitted bits are start, 4 -5 -6, Sam's publication TV Typewriter on the CRT. A slightly different version stop -stop. The middle figure shows the Cookbook by Don Lancaster. If pos- of the KSR electronic TTY puts out electrical equivalent as would be sibe, avoid the TTY service manuals something called an RS -232 signal, an transmitted by an electronic keyboard and handbooks; you need a whole industry -wide TTL (transistor-transistor using the EIA's RS -232 standard. Note set to find out what's going on and logic) compatible signal used for direct that mark is now "O" (zero) and the the Cookbook is faster and more connection to computers and some mod- waveform appears as a conventional easily understood. ems; but it's still a "dumb" terminal.

ELEMENTARY ELECTRONICS /September- October 1977 43 www.americanradiohistory.com I@Ag PHONING THE FUTURE For computer use a terminal -whether TTY or electronic with CRT -is generally arranged in the full -duplex mode, What's a "smart" terminal? An elec- FULL DUPLEX meaning the keyboard and display are tronic terminal with a built in mini- RECORDER independent of each other. In some computer. A smart terminal allows the OR instances the keyboard will have an PUNCH user to type a full page into storage, associated reader that can provide output 4 examine the page for errors, make cor- from a punched tape (or other player), rections, and then transmit the signal. while the display has an associated recorder, or a punch for paper tape. If In some smart terminals additional in- DISPLAY (CRT ECHO OR PRINTER) there is an associated reader and punch formation can be typed into storage as the complete terminal is an ASR (Automatic the previously entered information is COMPUTER Send and Receive). sent out. On the receiving end, a smart The keyboard sends the characters to terminal can often store several pages the computer which in turn sends back an READER KEYBOARD of transmission, allowing the user to INPUT instantaneous echo to the printer/display. electronically roll back to previous It appears to the user that he is typing directly to the display though there is, in pages. (A full screen is usually a connection the page.) Some terminals fact, no direct between smart are actu- keyboard and display. ally full computers with built in KSR and can store thousands of words, but this is esoteric equipment. The typical hobbyist and time-share user is more likely to use an inexpensive, dumb KSR HALF DUPLEX In the half -duplex mode a form of electronic terminal such as the highly ECHO multiplex device somewhere in the system can be a simple wire rated Micro -Term ACT -1, which has ECHO overall -it DISPLAY KS from the keyboard-sends the keyboard 300 baud (we'll explain baud later) +-- signal to the display even if the com- OUTPUT RS -232 output that can be fed directly puter's echo is turned off. If the echo is to a hobby computer or into a modem left on the display will show each MULTIPLEXER COMPUTER such as the Omnitech 701A (the in- character twice, once from the direct dustry "work horse" available used for connection from the keyboard followed the Half- duplex is generally about $150) that has both a TTY and INPUT by echo. used RS -232 connection. KEYBOARD when the terminal operates at baud rates For those who need both a direct too fast for the printer to follow the RS -232 output and a modem, but who echo, or too fast for the computer to incoming don't want the modem as an extra handle the character plus the echo. In time -share and hobby personal piece of gear with its required wiring READER computer systems the echo is usually there is the ACT -2 terminal shown in turned off at baud rates higher than 300. the photographs. The one shown is a prototype sent to ELEMENTARY ELEC- TRONICS for test and evaluation. It is something termed baud or baud rate. width for a total of 100 msec. Now essentially the ACT -1 with a built in Very simply, baud is expertese for soMe- baud, or baud rate is very simply the modem. thing we used to term pulse width, or reciprocal of the pulse width of each Baud. Whether you go into personal time; it's sort of like when the experts bit. Since the pulse width of each or timeshare computer systems you're decided to upgrade electronics by de- ASCII TTY bit is 9.09 msec the baud going to hear and read much about ciding we must all call cycle -per- second rate is 1/.00909, or 110. That's all hertz. there is to it. We could just as easily In order for electronic systems to communicate there must be some form of synchronization; each character or command must be transmitted and received in a specific time interval. If a printer was programmed to receive a character in say, 100 milliseconds (msec.), and it received one and a half characters in 100 msec., obviously it would be confused and display incorrect information, just as it would if it received only half the character information in 100 msec. Nothing could be simpler than using the As you might have guessed, we ACT -2's coupler. Just place the telephone Here it is -the standard of reference for achieve synchronization by transmitting handset in its niche and have full access to and personal computer such systems as Call Data which many time -share any character in a specific time interval. installations. This model 33 teletype is accommodate virtually all programming If you refer to the illustration of an used whenever hard copy, a written languages. Call Data, for instance, can do record, is required. The model pictured is ASCII TTY signal you'll note it con- such things as feed back a cross assembler an ASR -Automatic Send and Receive. sists of 11 bits -the start bit, 7 character for your personal computer, or provide Visible to the left is the paper tape punch bits, parity, and two stop bits -with access to the Dartmouth University and reader. each bit being precisely 9.09 msec. in program library.

ELEMENTARY ELECTRONICS /September- October 1077 www.americanradiohistory.com When a terminal is switched to the local mode the keyboard is connected directly to the display via a loop, and the computer is disconnected. In this way the RECORDER keyboard entries are fed directly to the printer and tape punch of an ASR TTY, and tapes can be prepared for feed to the computer at a later time. It also permits OUTPUT DISPLAY characters such as control functions to be i added to a punched tape that has been previously made from a feed by the COMPUTER LOOP- computer using the full or half duplex Here we have both the accepted standard TH RU modes. (In half -duplex the computer can of the industry and a promising new- KEYBOARD J feed the display if the keyboard is not in comer. The modem on the left is the INPUT use. This is usually accomplished by Omnitec 701A and originally cost more sending special control signals to the than $400. It handles both TTY and RS -232 computer.) In electronic terminal systems inputs and can be directly connected (hard with CRT display the recorder might well wired) to the phone line; it also provides be a digital tape recorder rather than a half and full duplex switching. Used ones TTY -type tape punch. can be had for about $150. On its right is the new Omnitec 501A- specifically made for the model 33 TTY. It is available fully A terminal can be connected to a corn - assembled for $150, and as a semi -kit for puter through voice -grade telephone $100 -all PC board wiring complete, it just circuits using a device termed a modem, needs to be placed in its cabinet. It too an acronym for modulator -demodulator. provides both half and full duplex. Avoid The modem converts the terminal's hobby -type modems which do not have a Or MODEM electrical pulses to tones in the duplex switching option directly available TERMINAL approximate 1000 to 2000 Hz range. When on the front or rear. the tones are received by the computer's TELEPHONE modem they are converted back to minute they cannot print faster than the CIRCUIT electrical signals. Each modem is a two - information is transmitted, and the limi- way device: the computer's modem tation remains the speed at which the MODEM converts the computer's signal to audio ASCII characters are transmitted. But, COMPUTER tones and feeds it to the terminal's the ASCII format applies to the se- modem where it is converted back to an quence of the eight bits making up the electrical signal for the printer or display. To avoid confusion between the terminal character and parity (a self -checking and computer the tones from the terminal feature). If each bit were shortened are completely different from the tones each character would take less time to generated by the computer's modem. transmit, and that's exactly what is done. By general convention, for most personal and time -share high speed have called it the "Irving rate," the minute typing rate, which is fine for terminals the character bit rate is short- "Gloria rate," or the "9.09 rate." We someone typing away, but slow when ened from 9.09 msec to 3.3 msec., call it baud rate, and a 110 baud rate getting information back from a com- Almost three times as much information is always 8 -level TTY speed. puter. may be transmitted within a given time Trouble is, the TTY is capable of Though there are printers capable of interval as compared to a 110 baud printing a maximum of 100 words per displaying more than 100 words per TTY. If we find the reciprocal of 3.3 msec (1/.0033) we get an answer of 300, meaning a 300 baud rate. You will find most hobby CRT terminals such as the ACT -1 and ACT -2 to be 300 baud. The fact that 110 baud means 100 words per minute and 300 baud means 300 words per minute doesn't mean there is a direct relationship between baud rate and words per minute. The close relationship is purely accidental. (If you get out the calculator and start multiplying you'll probably claim a 300 baud rate should produce less than 300 words per minute. The "error" comes in because the TTY signal ha; two stop bits which take up a total of 18.18 This actual prototype of an ACT -2 uses an older ACT -1 (hence the label) with a built -in modem for interfacing to the telephone lines. The video output feeds a msec. The complete TTY signal is 11 TV monitor (CRT) and the two pieces make up a complete terminal. Inputs and hits; start, 8 characters with parity, 2 outputs are RS -232 and when phone plugs are inserted the modem is automatically stops. The 300 baud system has only disconnected. A switch for full duplex or half duplex is located directly under the one stop bit -ten bits total for the phone jacks. Using the modem is just a matter of pulling the plugs and then character -so the stop is 3.3 msec, placing the handset in the coupler. (Continued on page 104)

ELEMENTARY ELECTRONICS /September- October 1977 45 www.americanradiohistory.com On a warm spring day a few months ago we packed off the ELEMENTARY ELECTRONICS staff to a wedding at Ben- ton Harbor, Michigan. Right! That's the home of Heathkit, and the wedding was between Heathkit and the Digital the Heath Name Equipment Corp., more generally known as DEC. Now when you have two giants getting together, Heathkit of Computer Systems electronic kit renown and DEC, one of the biggest names in microcomputers Flexibility is the keynote as these new kits can whose PDP -11 is considered by even be scaled from home and hobby to industrial use. the Pentagon as the best designed computer system, we're entitled to expect some new and impressive breakthroughs Heath's H8 computer has in personal computer kits. been designed with the Well, we got more than we ever hobbyist in mind. It is expected, or dreamed was possible in built around the hobby's kits. Basically, Heathit and DEC have most popular microproces- come up with a system concept that can 8 -bit 8080A. The sor, the be scaled to accommodate any needs, H8 also features a built -in to 1K x 8 ROM which con- from hobby /personal computing edu- tains a monitor program. cational, small business or industrial The front of the H8's use. panel contains a 9 digit, Top of the Line. The Rolls -Royce of 7 segment octal display. the new Heathkit line is their H -11 Digital Computer which features the prewired DEC LSI -11 microcomputer module. With a teletype interface the Heathkit H -11 is essentially a PDP- 11 /03 minicomputer, which uses DEC software such as the DEC BASIC and Heath's top of the line H11 languages, PAL -11 assembler, is a 16 -bit digital computer. FOCAL The H11 utilizes a 16 -bit on -line debug, etc. This all might sound central processing unit (fully at the present time like a lot of gobbly- wired and tested) with 4K gook, but those who have any back- x 16 dynamic RAM; the ground in using minicomputers realize memory expandable to a that we are talking about the general full 20K. Remember, this is availability of software (programs) a 16 -bit system -so the basic from DECUS, the DEC user's organi- memory is equivalent to 8K makes a whole in an 8 -bit memory board. zation. In fact, Heathkit new ballgame out of personal computing because the hobbyist no longer ends up with a "black box" for which he must now locate software. The H -11 comes complete with the BASIC and FOCAL higher languages, editor, etc. Just this package alone will give you computer facilities exceeding those of Heath is now making the LA36 DEC Writer II avail- many schools with extensive computer able for use with their programs. Fact is, the average hobbyist new computer systems. will probably end up with a lot better The LA36 features an computer installation than his son uses ASCII encoded upper/ in school. lower case keyboard with Heath Support. Just as Heathkit sup- characters. 95 printable ports the builder with software at the The terminal can operate time construction, so too will they on either full or half- of duplex, and has a parity support the user in the future through check on output. self -instructional programming courses and a Heath User's Group (HUG) which will share new programs among users of the H -11. CIRCLE 31 ON READER SERVICE COUPON The mail -order price of the H11 with

46 ELEM ENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com its software package is $1295. Acces- sories include a serial interface ($95), parallel interface ($295) and a 4K x 16 The H9 alphanumeric video termi- static RAM (Random Access Memory) nal is designed to accompany the H8 and H11 computers, but will Keep in ($275). mind the H11 is a 16 work with any digital computer. bit system, so 4K memory really is The H9 features a full 67 key equal to 8K in the typical hobby/ ASCII keyboard with a 12 -line, 80- personal computer. character format on a 12 -inch CRT. A Computer for Everyone. For those It also features: an option of four who find the H -11 somewhat expensive columns of twelve lines -20 characters Heathkit also showed their 8 -bit digital wide, a cursor control, batch transmit, and plotting ability. computer called the H8. The H8 is built around the 8080A microprocessor and is configured for 32K of memory with a total capacity of 65K addressable memory. Unlike most other 8080A personal computers which are "black boxes" with front panel con- soles that require initial keying by hand of the loading program, the Heathkit H8 computer has a built -in monitor program in ROM (Read Only Memory) for controlling the front panel and load -dump operations. Speaking of the front panel, it's like nothing we've seen before on a hobby/ personal computer using the 8080A. The H10 Paper Tape Read- Firstly, the H8 has a 16 -digit keyboard er /Punch Unit is intended for entry of data and control functions. for use with the H8 and A 9- digit, 7- segment octal display can H11 computers. The H10 show the register and memory is a mass storage peripher- contents, al unit that will also func- while a built -in speaker and LED status tion with all other digital lights permits the user to monitor ma- computers. It uses the chine states. Again, Heathkit doesn't standard size roll or fan leave you stranded with a "black box." folded tape. The reader sec- The H8 kit sells mail order for $375 tion reads tape at 50 char- and includes a fully wired CPU (central acters per second (cps). processing unit), assembly and operations documentation, and all systems software on audio cassette. Accessories -which many of you must use -include an 8K memory board with 4K of static RAM (Random Access Memory) for $140, a 4K expansion chip set for $95, a serial interface board with 1200 baud (very fast) audio cassette inter- Heath's new kits face make for $110, and a three port parallel the home computer sys- interface for $150. tem a reality. It lets you Talking To Your Computer. Okay, computerize your home, you've got a computer, now how do and live in the future you talk to it? If you still want to take today. A computer in the kit route Heathkit has a 12 -inch the kitchen can keep CRT terminal called the H9 which sells your worries on the shelf. mail order for $530 including the cabinet. The H9 utilizes the full 67 character ASCII keyboard with a 12 -line 80- character format, cursor control, batch transmit and a plot mode. The standard serial interface (connection to the computer) includes EIA, TTL, and 20 mA loop (for teletype). The Baud rate is selectable from 110 (Continued on page 100)

ELEMENTARY ELECTRONICS /September- October 1977 47 www.americanradiohistory.com

Master Truckers Learn On inOrucks time and money. the student's s saving c heck drives which will habits beginning system of bad driving in - teach to the printouts driving trucks being added clutch, tin y tYPtypewritten the clutch. . making as riding 30 different Electronic Training Institute, driving,, cured, such 13 to Driver s using must be have on. at the the big rig which (big trucks and so wheel, inac- drivers to drive operate Wrong gear truckYork, learn student drivers oP con- full-sized rad¡o- radio- n egear "drives" using New simulator.ulator. the tiny ratios-"speeds"),student and brakes, including Brooklyn, truck signals to parking lots While the clutch, maneuvers, Which send roads, P multi-speedeed his the instruc- radio-controlled on table-top Driver Training ator, duplicates along With Ze controls, operate the celer, truck exactly actually full-sfull-size Which director of more than controlled students observe, whichWhich could trolled truck Herb Gruen, Simulator eqequals Other failures etc. on a truck. "end his mistakes. vehicle rs failure, and highways. days a full-size c can introduce loss, that four driving trucks ® tor, oil-Pressure says practice "The real the road, Institute of actual P Gruen adds. on nature tractor-t weeks is occur left m cab two mistakes. a computer body andan savesmoves costly trailer's carries it up." successful removed)moved) $25,000 and been so tha` (cover receiv- has ctroncs f The emulator electronicsI com- and executing full - ingma student's siznds from controls: sized wheel, brakes, - and pedal. Stu gas is clutch, lower left dent at while watching backing action via rear- photo M iddle vieww mirror. show electronics. (below) is the mock- Lower right for multi -speed utcft Picture a practice. "driving" shows student forward.

ELEMENTARY ELECTRONICSíSeptember- October 1977 www.americanradiohistory.com las Vegas LED Always win oribe red with electronic roulette 4,,Walter Sikonwí

alb 41. .44111P7 4A, 441

Tak3 a look at the schematic diagram. The voltage across capacitor C3 is our control voltage, and you can see how pressing S2, the accelerate button, charges the capacitor through R13. Once S2 is released, charge accumu- lated on C3 drains away through R13, PEOPLE HAVE .kLWAYS BEEN fascin- behind our Roulette game. We start R11, and decay control R12. Setting ated by games of chance, as di- with a very simple voltage -controlled R12 to its maximum resistance pro- versions and obsessions. Inverte- oscillator. We then devise some means duces the slowest rate of capacitor dis- rate gambler or not, chances are you'll for converting the oscillation of our charge; hence, as we'll see later, the really like Las Vegas LED, our version VCO into the apparent revolution of a revolving light will take a maximum of that old favorite, Roulette. Here's spot of light (this might seem hard, but amount of time to come to rest. more good news -you won't have to we'll see how simple it is later) ; the Brake switch S3 also discharges C3, drop a bundle to cash in on the fun. velocity of the light will be directly this time through R14. Since the re- Las Vegas LED's spinning wheel proportional to the VCO's frequency. sistance of R14 is set to a relatively of fate is a revolving dot of light, pro- The VCO's frequency, however, is pro- small value, the rate of discharge is vided by a ring of ten LEDs. A glance portional to the control voltage applied quite rapid, and produces a quick cut at the photographs will show you that to it. We can produce acceleration of in the speed of the light. It is the volt- play is governed by three controls: Ac- the revolving light if we cause the age on C3 that is to be our control celerate, brake, and decay. You start by VCO's control voltage to gradually rise voltage. Transistor Q11, functioning pressing the accelerate button, which while the accelerate button is depressed. here as an emitter follower, reads C3's causes a red dot of light to revolve at Conversely, deceleration of the light is voltage; and because the emitter fol- an ever -increasing rate until a terminal synonymous with a gradual reduction lower configuration is used, Q11 will velocity is reached. If you release ac- in control voltage. How do we produce not significantly contribute to the dis- celerate, the spinning light will gradu- a control voltage that behaves in such charge of capacitor C3. At Q1 l's emit- ally coast to a standstill. The rate of a manner? We can charge and discharge ter we now have a voltage proportional deceleration is determined by the decay a capacitor through resistors, and use to that on C3, which is used to drive control. Pressing brake while the light the voltage across the capacitor as our our VCO. is coasting causes a more rapid, but control voltage. Unijunction transistor Q13, along not instantaneous, halt to the spinning. with R16, R17, R18, R19, and C4, At least two games are possible, with cw comprise a relaxation oscillator, the this control format. Using a little imagi- frequency of which is proportional to nation, you can probably devise more. NO.B the input voltage present on the left - The first possibility is similar to stand- N0.9 0 N0.1 hand end of R16. We don't have the ard Roulette. A player presses acceler- O N0.8 O nice, linear, voltage -to- frequency con- ate, then releases it, and hopes that the NO I N0.9 version of fancier VCOs, but what we number he has predicted beforehand CCw have serves our purpose well enough. will be the one at which the light ulti- NO 7 N0.3 The output signal of our VCO appears 0 NO 3 NO.7 mately comes to rest. Alternatively, the across R19, and is a series of short - player starts the light into motion; then, duration spikes with an amplitude of a upon the release of accelerate, he tries NO 5 N04 volt or two. Such a signal won't be to stop the light on a number designated N0.40 O N0.5 acceptable to the circuitry that follows, by his opponent, using only one pulse so we first feed it to transistor Q12, set N0.6 of the brake switch for this purpose. NO.2 up so that only a small input signal This second variation is quite a frus- O NO.10 Q saturates it fully. The resultant output trating game; particularly so if various N0.2 N0.6 signal, available at Q12's collector, is a decay times are used. Decay times from N0.10 well- defined series of negative -going about 1.5 to 15 seconds can pulses, approximately be selected Mount the LEDs in one of the two 9 volts in ampli- via orders the decay potentiometer. shown here, which one depending on tude. How It Works. Before discussing whether you wish your wheel to "rotate" Now we convert the variable -fre- construction, let's delve into the theory clock -wise (cw) or counter -clockwise (ccw). quency pulses from Q12 into the ap-

ELEMENTARY ELECTRONICS /September- October 1977 49 www.americanradiohistory.com rent to illuminate an LED. Whenever a particular output is high, its associated I LAS VEGAS LED driver transistor will supply current to a LED, and light it. parent revolution of a dot of light by We arrange these LED's in a circle using an integrated circuit known as a so that as we progress in a clockwise decade counter. One essential character- direction, starting at the LED associated istic of such an IC is that it has ten with output #1, we encounter, in outputs, and at any given instant of proper consecutive order, those LEDs time, nine of these outputs will be at a associated with output #2 through out- low potential, while the tenth will be put # 10. When we feed an input signal high. The second important feature of to our IC, we see the LEDs fire se- the decade counter is that whenever its quentially so that a spot of light ap- input, (pin # 14 in this case) , senses a pears to be revolving in a counter- specific change in potential (high -to -low clockwise direction. One full revolution in this case), the lone high signal ad- of the light requires ten input pulses, vances serially along the outputs. Spe- and the rate of revolution is in direct LEDs are to be wired to the foil side, with cifically, successive input pulses to IC1 proportion to the input frequency. their leads left long enough that their heads will cause the high signal to advance Let's review what we have: i) the poke through the front cabinet (see text). from output #1 all the way to output frequency of our VCO is controlled by Observe polarity; the negative leads of the #10, and then back to output #1 the gradual charge and discharge of a LEDs are notched, as shown, and should be as both the pictorials and the again. You might logically assume out- capacitor; 2) the variable- frequency connected schematic indicate. put #1 to be available at pin #1, and signal from the VCO feeds a decade so on; however, this is not the case. We counter, which drives ten LEDs; and won't discuss the actual location of the 3) proper LED arrangement results in cabinet to accept the ten LEDs. With individual outputs, because this infor- the apparent revolution of a single dot a compass, lay out a small circle on a mation is available on the data sheet of light, with a velocity proportional to sheet of paper. If you intend copying that accompanies this Radio Shack IC. the frequency of the VCO. That's all the PC layout provided, the circle's From the schematic, we see how Q12's there is to it. radius should be exactly .9 inch. With a output feeds IC1's input, pin 14. The Wiring. Since nothing about the cir- protractor centered at the circle's cen- at 36- outputs of IC1 (pins 1 through 7, plus cuit is critical, you may build it any ter, divide the circle into arcs pins 9, 10, and 11) connect to ten way you wish. Perfboard construction degree intervals. Trim away any excess LEDs through buffer transistors Q1 is good. Alternatively, you might want paper, leaving just the circle and a small through Q10. These buffers are emitter to copy the PC layouts provided; the border around it. Position the circle followers; they're necessary because the choice is up to you. A good place to conveniently on your cabinet, and tape IC alone cannot supply sufficient cur- begin construction is by drilling your- it down. With a fine, sharp awl make

RIO I-_ +

IC PIN I R9

II\ +

IO Q3 TO B +ON MAIN BOARD

B- B-ON R4 DISPLAY LED CONNECTION POINT (LED R5 B+ ON OTHER ON DISPLAY SIDE.) TO B- ON MAIN BOARD

MAIN BOARD DISPLAY BOARD

IC pins are The component sides of the main and display boards are shown in this pictorial view. Make certain that the main board's all interconnected properly to the solder -points on the display board, as labeled. Connect, for example, IC pin 1 to Q10. Don't forget about R11 which is not shown and is wired point -to -point between R12 and 52.

/September- October 1977 50 ELEMENTARY ELECTRONICS www.americanradiohistory.com slight indentations in the cabinet at the symmetric pattern is employed instead +, and the ten counter output leads. points where the circle is subdivided of the usual rectilinear layout. The main board contains the rest of into arcs. Remove the circle, and at When installing components on the the components. Note that if the PC each indentation drill holes through display board, follow the dimensional patterns supplied are copied, the main which the LEDs can protrude. details in the accompanying drawings. board may be stacked right behind the The drawing given shows the order Note that Q1 through Q10, and R1 display board. This makes for a very of mounting of LEDs for both clock- through R10 mount on the component dense packing arrangement, but if you wise and counterclockwise revolution. side of the board. LED1 through have ample space, the boards may be The PC layout supplied for the display LED10 mount on the opposite foil side, mounted in any manner you like. R11 board provides counterclockwise revolu- with leads of such a length that the tops does not appear on either circuit board; tion of the light. of the LEDs extend beyond the spacers instead, it is wired point -to-point be- The majority of the components and through the cabinet's panel. The tween R12 and S2. Be sure to use a 16- mount on two circuit boards -either semiconductors that mount on the dis- pin socket for IC1. This IC is a CMOS the main board or the display board. play board are not especially fragile, unit, and should be inserted into its Even if you decide not to use a PC but as is the case with all solid -state socket only after all soldering is fin- board, the PC layout provided for the devices, excess heat can be damaging. ished. If, in checking out your unit, display board may be helpful to you. Solder all connections quickly, using a you should find an error that requires Note that the arrangement is particu- 25 -watt iron and fine, rosin -core solder. rewiring, remove IC1 before applying larly simple, even though a good many Twelve wires will run between the dis- a soldering iron to the board. parts are involved, because a radially play board and the main board; ground, In assembling the circuit, pay atten-

+9V

S2 --I ACCELERATE RIB 0 27K SI b li +9VDC R13 V / IOOuI .luf IOOK +l RII I-- S3 e R16 BI - !r` T 150K BRAKE IOOK 9VDCT R20 V C3 < R15 1K e RI 2 22uF 68K C4T DECAY 2M .47uP RI9 IDOK 220n (6 AA CELLS IN SERIES

/1 -15-II Inside 16 view of Vegas LED 2 15 +9V showing stacking of PC 3 14 boards. 4 ICI 13 5 12 NC. 11 021 031 04 05 031 071 081 091 010 C 6 II 7 10 8 9 - L ED LED LED LED LED LED LED LED LED LED 2, 3, 4/ 5i 6/ 8/ 9/ 10/

\\ RI R2 R3 \\ R4 R5 ç\\ R6 '1/4 R7 \\ R8 \ R9 RIO 3.3K 33K 3.3K 3.3K 3.3K 3.3K 3.3K_ 3.3K 3 3K 3 3K

Completed Vegas shown fully assembled, and installed in case.

PARTS LIST FOR LAS VEGAS LED

B1 -Six AA (penlight cells) 1.5 VDC (Radio Q13- Unijunction transistor (Radio Shack 276- R19- 220 -ohm resistor (Radio Shack 271 -000 Shack 23 -552 or equiv.) 2029 or equiv.) or equiv.) C1- 100 -uF, 16 -VDC capacitor (Radio Shack R1- R10- 3300 -ohm resistor (Radio Shack 271- R20 -1000 ohm resistor (Radio Shack 271- 272 -955 or equiv.) 000 or equiv.) 000 or equiv.) C2 -.1 -uF capacitor (Radio Shack 272-135 or R11- 150,000 -ohm resistor (Radio Shack 271- R21- 100,000 -ohm resistor (Radio Shack 271- equiv.) 000 or equiv.) 000 or equiv.) C3- 22 -uF, 16 -VDC tantalum capacitor (Radio R12- 2- Megohm potentiometer (Radio Shack Sl -SPST Toggle switch (Radio Shack 275 -612

Shack 272 -1412 or equiv.) 271 -093 or equiv.) or equiv ) C4- .47 -uF, capacitor (Radio Shack 272 -1071 R13, R14, R16- 100,000 -ohm trimmer (Radio S2, S3 -SPST pushbutton switches, normally or 272 -1404 or equiv.) Shack 271 -220 or equiv.) open (Radio Shack 275 -1547 or equiv.) IC1- Decade Counter /Divider CD4017 (Radio R15- 68,000 -ohm resistor (Radio Shack 271- Shack 276 -2417 or equiv.) 000 or equiv.) LED1 -LED1O -Light Emitting Diodes (Radio R17- 47,000 -ohm resistor (Radio Shack 271- Misc. -Battery clips (Radio Shack 270 -325 or Shack 276 -026 or equiv.) 000 or equiv.) equiv.), IC socket (Radio Shack 276 -1998 or Q1- Q12- 2N3904 transistors (Radio Shack 276- R18- 2700 -ohm resistor (Radio Shack 271 -000 equiv.), aluminum spacers, wire, solder, 1603 or equiv.) or equiv.) hardware, etc.

ELEMENTARY ELECTRONICS 'September-October 1977 51 www.americanradiohistory.com TEN FRONT - PANEL LAS VEGAS LED HOLES THROUGH WHICH (D/1@ THE LEDs PROTRUDE LEDs MOUNTED ON FOIL SIDS SO THAT TOP OF LED IS 5/8 tion to the orientation of C3 and Cl. ABOVE SURFACE OF BOARD Likewise, make sure the transistors and IC are correctly positioned. The LEDs must also be properly oriented. The leads of all these devices are identified on the packages in which they are sold. Because of the circuit's low power consumption, six 1.5-volt penlite cells in series will power it for a long, long time. A single 9 -volt transistor battery 1/4° N0.4 could also be used. BOLT Because this is not a finicky circuit, 1/2° NO .4 the operating controls and circuit boards THREADED SPACER can be,mounted in any convenient way inside your cabinet, but be certain to NO 4 NUT The two boards may be easily and neatly allow sufficient room to accommodate mounted to the front panel by following the batteries. When you've completed the method shown here. Make sure you cutting and drilling the cabinet, finish in NO. 4 BOLT leave the LEDs enough lead, and that you off the front panel with press -on decals. mount them to the foil side of the display As shown in the photographs, LED1 board. through LED10 should be identified with numerals applied in a random order. display is equally undesirable. it, and press brake. Note the rate at Final Calibration. After assembly is Release the accelerate button, and which the display is slowed down. Ad- complete, only a few simple adjust- the velocity of the light will diminish just R14 while alternately pressing ac- ments are necessary to put the circuit rapidly. Press accelerate again, and then celerate and brake until you obtain a into operation. Turn R12 so that its release it, repeating the cycle sevei.I rate of deceleration that you like. A resistance is at a minimum. Set R13, times, and at the same time adjust R13 very rapid braking action is undesirable; R14, and R16 to the midpoints of their to get an acceleration response that you the brake should diminish the velocity, ranges of rotation. Apply power, and like. In general, the best position for not halt motion instantaneously. depress the accelerate button. Within R13 will be somewhere in the middle The game may be used as already several seconds you should see a spin- of its range of rotation. described in the opening paragraphs.. ning dot of light. Adjust R16 for the Turn R12 so that its resistance (and However, just as dice can be found as desired maximum velocity. Too high a the decay time) is a maximum. Press constituent parts of many other games, maximum speed blurs the image and the accelerate button until the display so too can Las Vegas LED be spoils the effect, whereas a slow -poke reaches maximum velocity, then release adapted to games of your design.

o t ;11 8g8g8ge

1 88

Las Vegas LED uses two compact PC boards to keep its "wheel" spinning. The display board, on the left, takes advantage of a repetitious circuit to achieve a neat, clean symmetry of design. The main board, on the right, is also simple to etch and wire. Use these two full -size patterns as templates for your own Las Vegas LED.

52 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com COBRA 138 XLR CB XCVR PEARCE -SIMPSON LION 40 PRESIDENT JOHN Q.

CHECKOUT MIDLAND 77.882

ELEMENTARY ELECTRONICS has been sion receiver with jacks for external PRESIDENT JOHN Q. able to obtain more of the new 40 -chan- and P.A. speakers, LED digital chan- $169.95 (President Electronics, Inc.) nel CB transceivers for review, and pre- nel indicator, S /RF- output meter. General Description: A 40- channel sents the test reports here. These units AM transceiver for mobile, PA opera- are not prototypes, but are "stock stand- tion. Power supply 12 to 13.8 VDC ard," the same as the transceivers that PEARCE -SIMPSON LION 40 you can buy over the counter. If you $249.95 (Pearce- Simpson, Inc.) with negative or positive ground. don't find the particular unit you are General Description: A 40- channel Overall dimensions are 21/2-in. h x interested in reported on here, check AM transceiver for mobile, PA, base 61/4 -in, w x 93/s -in. d. Front panel the newsstands for the 1977 edition of operation. Delta tuning ± 1.5 kHz controls and switches for Channel the CB BUYERS GUIDE. is provided. Power supply 12 VDC to Selector, Volume, Squelch, Micro- 13.8 VDC with negative or positive phone Gain, Panel Light Dimmer, COBRA 138 XLR ground. Overall dimensions are 21/2- PA /CB, ANL, Local /Distance Sensi- $349.95 (Dynascan Corp.) in. h x 71/2-in. w x 91/2-in. d. Front tivity. Standard accessories are micro- General Description: A 40- channel phone, mobile mount, DC power AM /SSB transceiver for mobile and cable. ± PA operation. Fine tuning 1.5 kHz Receiver Section Test: is provided. Power supply is 12 to Input Sensitivity 0.4 AV 13.8 VDC with negative or positive Adjacent Channel Rejection 51 dB ground. Overall dimensions are 2%- AGC Action 11 dB in. h x 77/a -in. w x 101/2-in. d. There Input Level for S9 40 AV are front panel controls for Channel Transmitter Section Test:

Selection, Volume, Squelch, AM/ RF Output _ 3.8 watts LSB /USB, RF Gain, Voice Lock, Modulation to 85% yes CIRCLE 69 ON READER SERVICE COUPON Dynamike, Tone, LED Dimmer, and Relative Sensitivity for switches for ANL /Noise Blanker, panel controls and switches for Chan- PA /CB. nel Selector, Volume, Squelch, RF Receiver Section Test: Gain, Tone, SWR Calibrate, S /RF/ Input Sensitivity 0.3 IN AM SWR Meter, ANL, Noise Blanker, Adjacent Channel Rejection 67 dB PA /CB, CB thru PA Speaker, and Delta Tune. Standard accessories are microphone, mobile mount, DC pow- ,r ®y er cable. 4"*..**( Receiver Section Test: Input Sensitivity 0.6 AV CIRCLE 71 ON READER SERVICE COUPON Adjacent Channel Rejection 62 dB 85% Modulation dB CIRCLE 67 ON READER SERVICE COUPON -35 AGC Action 9 dB Modulation Limited to 100% yes AGC Action 8 dB Input Level for S9 300 AV Editorial Remarks: The President SSB Opposite Sideband Transmitter Section Test: John Q. has a relative reading S- Rejection 50+ dB RF Output 3.7 watts meter, double conversion receiver, ex- Input Level for S9 20 AV Modulation to 85% yes ternal and PA speaker jacks, LED Transmitter Section Test: Relative Sensitivity for digital channel indicator, and S /RF AM RF Output 4 watts 85% Modulation -32 dB output meter. SSB RF Output 11 Watts P.E.P. Modulation Limited to 100% yes Modulation to 85% yes Editorial Remarks: The Pearce -Simp- MIDLAND 11.882 Relative Sensitivity for son Lion 40 has a relative reading $199.95 (Midland Communications Co.) 85% Modulation -39 dB max. S- meter, double conversion receiver, General Description: A 40- channel Modulation Limited to 100% yes external and PA speaker jacks, and AM transceiver for mobile, PA oper- Editorial Remarks: A double conver- S /RF output meter. (Continued on page 101)

ELEMENTARY ELECTRONICS /September- October 1977 53 www.americanradiohistory.com Learn electronics easier...

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ttttttiti M tttttttit Ri tttittttttti HEATH -- - titi ti - ®! Schlumberger Order Form /Agreement Heath Company, Dept. 139 -331 Benton Harbor, Michigan 49022 Please send me items checked below and include FREE $7.95 - Our most advanced self -learning computers and more. Assumes value Weller Soldering Iron (GDP- 1105). course prepares you for the completion of Heathkit courses Send one course (checked below) with the Experimenter /Trainer (ET -3100) at the special price world of computers and micro- 1 through 4 above, or of only $89.95 plus $3.00 shipping equiva- and handling. processors, with particular em- lent knowledge. The special DC (EE -3101) AC (EE -3102) phasis Semiconductors (BE -3103) on circuit design. Covers digital techniques experimenter/ Send me the Electronic Circuits Course (EE-3104) with the Exper- digital fundamentals, semicon- trainer helps you perform all imenter /Trainer (ET -3100) at the special price of only $99.95 plus ductor devices for digital cir- the experiments in the course, $3.00 shipping and handling. cuits, digital integrated circuits, and when you complete the Send all four of the courses above (EE -3101, 3102, 3103, 3104) Boolean algebra, flip -flops and course, build and design your with the Experimenter /Trainer at the special price of just $199.95 plus $4.50 shipping and handling. registers, sequential logic cir- own circuits. Course includes In addition, please send the following courses (less trainer): cuits, combinational logic cir- text, records and 44 parts for DC (EE -3101) AC (EE -3102) Semiconductors (EE -3103) cuits, digital design and digital 24 different experiments. Aver- for just $39.95 plus $1.50 shipping and handling each. applications. Discusses TTL, ECL, age completion time, 40 hours. Electronics Circuits (EE -3104) for just $49.95 plus $1.50 shipping CMOS, PMOS, NMOS; integrated 4.0 Continuing Education Units and handling. circuits; SSI, MSI and LS I; and a certificate for passing Send me the Digital Techniques Course (EE -3201) with its Exper- ROM's, PLA's, microprocessors, final imenter /Trainer (ET -3200) for only $109.95 plus $3.00 shipping and exam. handling. ORDER DIGITAL TECHNIQUES PROGRAM AND TRAINER.... $10995 Also send me that IM -17 VOM kit for just $32.95 plus $1.50 shipping and handling. Michigan residents add 4% sales tax. HEATH 1M -17 VOLT -OHM METER I enclose check money order for $ or Charge to my: BankAmericard Acct. No Exp Date All Electronic Learning Programs require a VOM to Master Charge Acct. No. Exp Date make electrical measurements. We suggest the Heath IM -17 as the ideal "all- purpose" unit. All If Master Charge, include Code No solid state with FET input for better accuracy. Portable Signature X battery operation, zero and ohms adjust, accessory probe jack. Comes with DC polarity switch, three test Name (please print) leads; batteries not included. Easy 3 hour assembly. ADDRESS ORDER KIT IM-17 $3295 CITY STATE ZIP ED -105A www.americanradiohistory.com FLASHMATE - THE PHOTOGRAPHER'S DREAM Photoflash problems vanish with this easy- readout solid -state meter.

Frank I. Gilpin

Any photographer, amateur or pro, including sunlight. The sudden light compromise is that you must take care will tell you the biggest bane of his life provided by the electronic flash causes to set the pot directly on the reference a is figuring exposures for electronic flash a sudden drop in the phototransistor's marks before taking readings for photography. If you know the manu- resistance. This sudden drop in resis- given ASA. If you exercise care and facturer's guide number for your flash tance pulses the trigger circuit of Q2- patience when calibrating the unit, this unit, and if that number is close enough Q3. This pulse allows Q3 to charge will present no, problems in later use. to being accurate for your production capacitor C2 to a value proportionate The two PNP transistors Q2 and Q3 line unit, and if you can remember it to the intensity of the energy -producing are audio signal types and almost any will from one shooting session to another, light striking Q1. The value ' of this high gain experimenter grade units and if you remember how to use it, and charge on C2 is then measured by FET do. There are, however, few substitutes if your flash is fully charged, and if Q4, and indicated on the meter. Be- for Q1. It has a very high resistance to you use straight, harsh flash instead of cause of the high input resistance of ambient light, has a reaction time on the order of 2.8 microseconds and has bouncing it, and if. . . . Well, flash the FET, C2 does not discharge for photography is very often ifly. several minutes and you have plenty of a wide range of illumination sensitivity. Theoretically, you divide the guide time to take a reading. You can use a HEP -312, or a Clairex number by the number of feet between A discharge path for the meter and CL902, which also have the necessary the flash and subject, and the answer C2 is provided by R4 and S 1. The reaction times and ambient light resis- you get is the f-stop. This has to be switch turns the unit off and simultane- tances required to keep the trigger cir- figured for every shot, if you move be- ously discharges C2, leaving it ready cuit biased off until a bright, sudden tween shots and this guide number is for another reading, in about two sec- light is sensed. The FET, Q4, is a P- only good for one film type. Again, it onds. channel, small signal unit and there are gets pretty iffy. There are, to be sure, Sensitivity adjustments for varioUs a number of substitutions possible, such flash meters on the market, but the least film types are effected by adjusting R8. as 2N5461 through 2N5465. expensive one I know of costs nearly A rotary switch could be used to con- Assembly Options. You have a $100, and they are all rather bulky. nect a different trimmer resistor to the choice of assembly methods. Your The answer to these problems is meter for each ASA number, but that Flash -Mate can be ,assembled on a Flash -Mate. It's smaller than an Insta- would boost the cost, increase the size perforated board using point -to -point matic camera, inexpensive to build, re- ' of the unit and limit the number of wiring, or on a printed circuit board, liable and accurate, and easy to build, ASA numbers for which Flash -Mate for which the foil pattern is shown. with readily -available parts. It takes all can be calibrated. Layout is not overly critical and you the IF variables in stride, and gives Potentiometer R8 can be calibrated can vary the arrangement. Q1 is made you the right f-stop for any flash at any for any ASA value, and as many as you with a clear epoxy lens which is quite distance and for any film type from want. You can even add more calibra- durable, but an extra measure of pro - ASA 10 to ASA 400. Flash -mate can tions later. The only drawback to this tection can be provided by covering it be either of two basic types of meters. One, called an ambient light meter, Flash -Mate, a gadget that measures the light output of your flash, photographers have dreamed aimed right at it. The other type, for of for years, is here- measuring reflected light, is aimed at waiting for you to build! the subject and reads the light reflected It's not by the subject. Your Flash -Mate can expensive and it's type, as you be calibrated for either quick and choose. easy to How Circuit Works. The silicon assemble. phototransistor used as the light- sensing element in Flash -Mate has a very high resistance to ambient light, therefore the unit will work effectively under a wide range of lighting conditions, even

ELEMENTARY ELECTRONICS/September-October 1977 58 www.americanradiohistory.com ambient readings, or the reflected light reading mode, you will need a reliable electronic flash with an f -stop computer disc. You should also be sure the unit is charged fully, or has fresh batteries. Ambient Light Reading Calibration. Set the flash computer to ASA 400. Determine the distance -from -subject necessary for an f-stop of f22. For instance, if your computer says a distance of three feet for f11, two and a half feet for f16 and 18 inches for f22, place the meter on a table and the flash mounted on a tripod exactly 18 The layout of Flash- Mate's perf (or PC) To calibrate Flash -Mate you will need an inches in front of it. Carefully remove board is uncritical and the arrangements of accurate electronic flash with an f -stop the clear plastic meter cover. Turn on the components may vary. The roominess computer disc. Calibration can be done the meter and set R8 fully clockwise of the box allows for a clean layout either for ambient light or bounce flash. and after a few seconds to stabilize, fire the flash. The meter needle should TO TO TO travel all the way upscale. Adjust R8 SIB SIC R8 until the needle rests exactly on the uppermost reference mark of the meter scale. Label this spot "f22." Reset the meter with SI and consult your flash C3 Here's the component T computer once more to determine the side of Flash- Mate's PC distance for f16. Measure off this dis- board. The layout is sim- tance, set the flash at that spot and fire RIO ple and straightforward, which helps keep assem- it at the flash meter. The needle should bly time to a minimum. rest at a spot lower than the first. Mark Flash -Mate is a great this spot on the meter scale "f16." weekend project; accu- Take care not to disturb the setting of ú rIr rate, unique, and goes R8 during this calibration step. OFF- together easily. A B C RESET Follow this procedure all the way ON through the scale to f2, remembering to 9V reset the meter after each reading. BATTERY 3 -LUG MOUNTING CLIP STRIP When you've finished this step, replace the cover on the meter face and label the panel adjacent to R8's indicator The foil side of Flash - knob "400." Mate's board is quickly This completes the etched, especially if you calibration of the use this full -size pattern. meter scale for all ASA values and the You could reduce or en- calibration of R8 for ASA 400. Select large this as size and the next highest ASA on the computer layout are not critical in and find the distance for an aperture this circuit. of f16. Set the flash that distance from the meter and fire it. Adjust R8 until the needle rests exactly on the previ- with a clear pilot light lens or other hole in the cabinet facing the adjust- ously established mark for f16. Now clear plastic dome. The phototransistor ment slot in the trimmer. mark the panel adjacent to R8's indi- can be mounted in several ways. You Some potentiometers have a knurled cator knob and label it for the ASA can press -fit it through a rubber grom- plastic wheel for adjustment which can number used to determine the distance. met in the front panel of the cabinet, be manually roated regardless of its The meter is now calibrated for that epoxy it through a hole, or it can be mounting position. ASA. Repeat this step for each ASA mounted on the chassis board so that When you are sure all is in order and value desired. I have my meter cali- it is rigidly suspended behind a hole in you have double checked your wiring, brated for 25, 64, 80, 125 and 400, the the front panel. apply power to the unit with .S1. Turn five films I use most, but I can easily After all components are mounted R8 fully clockwise for least resistance add more at some later date by using a and wired to the chassis board and and adjust R10 until the meter needle reliable flash and the above procedure. connected to M1, R8, Q1 and S1 on rests on zero. After this one internal Reflected Light Calibration. The the front panel, check to make sure all adjustment, you can close the cabinet, best situation is to find any wall which polarities are correct. Remember that screw down the front panel and prepare is an 18 percent gray, but any neutral when the chassis board is mounted in for the calibration procedure. You'll color wall, or off-white bedsheet will do. the cabinet, you have to be able to need a tape measure, a tripod and a In this procedure, the wall (or a sheet reach R10 to make adjustments. If the flash unit. tacked up on a wall) becomes your shaft is slotted you can drill a small To calibrate Flash -Mate either for "subject." Using the reference flash

ELEMENTARY ELECTRONICS /September- October 1977 59 www.americanradiohistory.com Flash -Mate is one useful gadget -bag stuffer. Forget FLASHMATE about computing f -stops and concentrate on com- unit's computer to determine the first posing those pictures. The distance for f22 at ASA 400, place the photo- sensitive transistor (above the meter) meas- and flash this distance from the meter ures the light, and the wall. Both the flash and meter are meter reads directly in f- aimed at the same spot on the wall. stops. The unit can be cali- Fire the flash from just above and a brated to read either few inches behind the meter to avoid ambient light or for "blinding" it with a strong sidelight bounce flash photography, from the flash. Mark the meter face for depending on your own f22 and continue moving the meter and artistic preferences. flash farther from the wall until f2 is calibrated. Repeat for other ASAs as in the previous step. Using Flash -Mate. For the ambient R2 R6 R9 le 50 150 light reading model, the procedure for 27K taking a reading is as follows: Place 02 03 R5 Q4 Flash -Mate at the same location as the e C3 O 20M R8 subject, facing the flash, and set R8 for IOOK V. , MI the ASA of the film you're using and g . 00 uF it on. Place the flash where you C2 turn RI 100 RIO 4.7K CI 50K want it and fire it using the open flash R3 02 uF R4 - IOK IK R7 button. Read the f -stop from Flash uF 27K Mate and set your camera to that f- stop. To use Flash -Mate calibrated for re- BI + SI flected light readings, place it facing the 0 -11I1I1 subject in the same position as the flash. ON RESET /OFF from 9V Fire the flash, take the reading Schematic for Flashmate circuitry. Be sure when wiring in the transistors Flash -Mate and set your lens to that that you carefully observe lead keying, and always avoid allowing them to f -stop. heat too much. Personally, I prefer the direct, or ambient reading mode of calibration. b (NOT USED) For me, it offers more versatility. For example, your model need not be present to take a reading in advance. If you were going to shoot portraits using QI, P- CHANNEL 02, Q3 direct flash, bounce flash, or the popu- PHOTOTRANSISTOR FET, 04 lar umbrella reflector technique, you select need only set up the flash and PARTS LIST FOR FLASH MATE where the model will sit or stand for the picture. Place Flash -Mate at that C1- .02 -uF capacitor (Radio Shack 272 -1066 Shack 271 -000 in series) Shack position, take a reading and set your or equiv.) R6- 150 -ohm, 1/4 -watt resistor (Radio camera lens. When the model arrives, C2, 3- 100 -uF, 16 -VDC electrolytic capacitor 271 -000 or equiv.) 1/4 resistor (Radio all you need do is focus and shoot with (Radio Shack 272 -955 or equiv.) R7, 9- 27,000 -ohm, -watt 271 -000 or equiv.) no wasted time and wow, will you ap- M1 -0 -50 microampere DC panel meter Shack R8- 100,00 -ohm printed circuit board- mount- pear professional with no fumbling (Radio Shack 22 -017 or equiv.) Q1- Photo -sensitive transistor HEP -312 ing potentiometer (Radio Shack 272 -220 or over f -stop computations or camera or Clairex CL902 (Radio Shack 276 -130 or equiv.) If you plan to shoot from sev- - fiddling. equiv.) R10- 50,000 -ohm printed circuit board these 271- eral positions during the session, 42, 3- General- purpose PNP silicon transis- mounting potentiometer (Radio Shack spots and their readings can be de- tor, 2N5139 or HEP -51 (Radio Shack 276- 219 or equiv.) (Radio termined beforehand and noted. A 2034 or equiv.) S1-Single-pole, double -throw switch piece of masking tape on the floor Q4- Field- effect transistor, P- channel, 2N- Shack 275 -613 or equiv.) f on 5460 or 2N5461 (Radio Shack 276 -2037 or with the appropriate -stop marked Misc.- Printed -circuit board kit (Radio Shack equiv.) it will remind you of the correct set- 276 -1576 or equiv.); cabinet 61/4 -in. x R1- 4700 -ohm, 1/4 -watt resistor (Radio Shack ting for that position. This technique is 33/4 -in. x 2 -in. or larger (Radio Shack 270- 271 -000 or equiv.) also handy for those special awards 627 or equiv.); knob; hookup wire, hard- R2 -47 or 50 -ohm, 1/4 -watt resistor (Radio luncheons, handshakes, weddings, ware, solder, etc. Shack 271 -000 or equiv.) graduations, or any other planned above are R3- 10,000 -ohm, 1/4 -watt resistor (Radio Note: Radio Shack part numbers events. You can go a little early before Shack 271 -000 or equiv.) for capacitors intended for printed circuit of the event and take your readings and R4- 1000 -ohm, 1/4 -watt resistor (Radio Shack board mounting. If you use other type pick your spots from which to shoot 271 -000 or equiv.) construction such as perf board, axial -lead and when that once -in -a- lifetime event R5- 20- megohm, 1/4 -watt resistor (if not capacitors will be more convenient occurs, you'll have a perfect exposure available, use two 10- megohm, Radio to mount. of it.

60 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com PPUT[1 READOUT by Norman Myers, Computers Editor

Ols a pocket calculator a kind of micro- most of the scientific functions you could desirable feature to have in calculators; computer? What can a microcomputer do want and it is programmable. By pro- once you write and test a program you that a programmable calculator cannot? grammable we mean that a sequence of can use it many times over with confi- Which should I buy? These are some of key strokes can be stored in the calculator dence. Writing a program one day, then re- the questions you've mailed me. This and used repeatedly to solve problems. entering it a keystroke at a time into the month we will look at calculators, especial- More on this later. The Hewlett- Packard calculator weeks later, leads to errors, be- ly the programmable type. We will begin HP -25 ($175) is another popular key - sides being a bother. The classic calculator with an overview of calculators and recent programmable calculator but both the SR- for program storage is the HP -65 which electronic developments, then we will dis- 56 and the HP -25 cannot store programs shook the world just three years ago by cuss details of what calculators can do by after thé unit is turned off. The storage offering magnetic strips as the storage concentrating on the Hewlett- Packard HP- medium is called "volatile" as opposed to medium for programs. You write a pro- 65, and finally we will make some obser- "non- volatile." The HP -25C, however, gram., enter a tape in a side slot of the vations about how microcomputers and keeps the program stored with microwatts HP -65, a motor pulls it through and out calculators differ. of power from the batteries after the unit the other side. Your program is invisibly Scientific calculators contain various is switched off. A company called Casio written on the magnetic strip like voice functions, such as squares and square has a similar battery supported non -volatile patterns are stored on a magnetc tape. roots, and are distinguished from business memory approach with their 101 calcula- The HP -65 allows programs to be stored calculators which are generally simpler tor. for long periods and read back into the and have fewer functions. Scientific units Non -volatile program storage is a most calculator for replay at any time. Engi- have become very popular in the last two years for two reasons. Hand -held units have decreased to a fraction of their origi- The HP -65 is one mein, nal price while their mathematical powers WRITE programmable machine PROGRAM/ have increased. Power of these hand- RUN PROGRAM from Hewlett- Packard. It held units has increased in spite of the cost SWITCH was the first hand -held to cuts. The credit for increased power at less offer magnetic -strip cards cost goes to microelectronics -the micro- for memory storage and scopic transistors and resistors packed by is truly a classic the hundreds on quarter -inch square chips. calculator. Programs may Lower power consumption and higher be stored on the cards density of components on chips has made LABEL KEYS at any TO NAME and played back more storage available in random access PROGRAMS time in the future. Cards memories (RAMs) and more computing are simply entered into power available in arithmetic units. Fabri- the slot on the side of cation methods have been improved while the HP -65, and an sales volumes have increased, both of internal motor pulls the which allow prices to drop. STORE card through and out the If all this can happen to hand -held AND side. This RECALL other brought calculators, we can imagine what may KEYS the ease, reliability and happen to microcomputers. We have re- accuracy of pro- viewed several computers in this column grammability into the that are no bigger than a book and contain price range of many readout digits and a keyboard. I expect the workers in science and microcomputer market to become especial- industry. The calculator ly popular as microelectronics reduces has 35 multiple function computer sizes even more (probably to the keys, a few of which are size of hand -held calculators) and allows labeled in this photo. more and more storage. Prices may well Each key is marked with drop and microcomputers may become its basic function, and $100 tools required by some high school with two others which and college courses. can be chosen by the By looking at what has happened to user. Add to this the calculators, we can guess what will happen programmable capability to ni icrocomputers. and you have great Pick -A -Peck. There are dozens of hand- versatility. Once pro- held calculators on the store shelves. RUN /STOP KEY grammed, the HP -65 can Among the best known are the Hewlett - FOR INSERTING DATA run through complex Packard (HP) and Texas Instrument (TI) number manipulations calculators. Texas Instrument's SR -56 over and over again. ($100) has been a popular basic unit with CIRCLE 57 ON READER SERVICE COUPON

ELEMENTARY ELECTRONICS /September- October 1977 61 www.americanradiohistory.com Press COMPUTER READOUT 5 5 put into X register and displayed neers, technicians, businessmen, and hob- enter 5 bumped up to Y byists all had versatility they had never register thought possible. Today, a new calculator 3 3 put into X register and called the HP -67 ($450) offers over twice displayed the storage (224 storage locations versus + X + Y = 8 putintoX 100) and computing power of the HP -65 register and displayed at about one -half what the HP -65 cost 7 7 put into X, 8 bumped two years ago! Texas Instrument's SR -52 to Y ($250) and the HP -67 both use magnetic enter 7 bumped to Y, 8 cards for program storage and are thought bumped to Z by most to be the most powerful units 9 9 put into X available today. National Semiconductor's + X + Y = 16 put in X 7100 ($400) is expected to be on the and displayed, 8 drops market soon and will offer program stor- down to Y age of 4096 locations on read only mem- X (times sign) X x Y = 128 put in X ory (ROM) cartridges instead of cards. and displayed. The cartridges will reportedly plug into The calculation has been done in one the 7100 calculator. The user will, for smooth set of operations without having to example, be able to store about 40 pro- think of storing and recalling intermediate grams of about 100 steps on each cartridge. results. Results can be displayed in "fixed" Printers Too. Printers are also becom- or scientific format. To get fixed format, ing available for use with calculators. for example, press "DSP . 3 " (DSP is The HP -65 and its supporting software. The HP -97 has essentially the same func- one key) to get three decimal places Packaged with the calculator are user tions and storage capacity as the HP -67 (10.234) on the display. For scientific aids such as reference booklets, instruc- but the 97 is a bit larger and includes a notation, press "DSP 3" to get 1.023 X tion manual, pre- written programs -and printer which records data and programs 101 on the display. a selection of pre- recorded, magnetic on a strip of paper. Likewise, Texas Instru- The HP -65 has nine addressable registers card programs. ments has a printer (the PC -100) to which called R1 through R9 which can be used their programmables can be conneected. to store data. They are usually, used to of that number is simply transferred to the In summary, the input to calculators is store constants or intermediate results from X register. The HP -65 can also do a passel through the keyboard, and the output is the .X stack register. To store a number of fancy functions, like sine, cosine, logar- through the familiar LED displays or appearing on the display (and therefore in ithms, square roots, factorials, and more. through printers, or both simultaneously. the X stack register) one presses the STO These functions are needed in all types of Now let's look closer at the classic, pro- key then any number 1 through 9. The engineering and design fields such as elec- grammable, magnetic card calculator -the data will be stored in the selected register tronics, civil engineering, and architecture. HP -65. until over -written by another entry or until The calculator with these functions allows Classic HP -65. The HP -65 has 35 but- you turn off the calculator. To recover the student, layman, and curious hobbyist tons or keys and most of the keys perform and use the stored digits, press .the RCL to invent, experiment, and learn what can multiple functions. The basic function for (recall) key and the appropriate register be done. Suppose, for example, that a de- each key is marked in black on the top of number, 1 through 9. Recalling a number signer says adding more sound absorbing the key itself; but other functions are does not erase it from the register -a copy items to yogi- room cuts the noise by 20 marked near the key in yellow and in blue. The key with the number four on it, for SOME OF THE HP -65 KEYS AND THEIR USES example, also has a blue 1 /x and a yellow SIN associated with it. To make the key Keys calculate a reciprocal, press the blue "g" }, -, X,- Arithmetic functions. function key followed by the blue 1 /x. To get a sine function, press the yellow "f" 0 through 9 Used for entering data and with STO /RCL. key followed by the yellow SIN key. To get the inverse sine function, that is to enter Causes data to move up in stack registers as a computation "undo" the sine, press f-1 then SIN. aid. More on functions later. DSP Selection of number of decimal places. Numbers are stored and maniplated in the HP -65 in registers. Each number takes CHS Change sign. up one entire register and a number can be as large as 9.9999999 X 1099. (Re- STO, RCL For storing and recalling data from any one of nine registers. member, 1099 is scientific notation which simply means the decimal point is moved GTO "Go to" key tells calculator where to start in a program. 99 places to the right. 100 is 1.0 X 102.) The register containing the number on LBL, A-E Used to give names or "labels" to sections of a program. the display is called the X register. It is one of four registers in an "operational RTN Instructs calculator to return to start of program. stack," but only the X- register contents are displayed on the LED readout. The SST Used to single step through a program. four registers are called X, Y, Z, and T, Run /Stop used to stop program temporarily. but could be called anything you like. The R/S value of a stack is that it aids in solving f, g There are "f functions" marked in yellow on many keys, and equations by reducing the need to store "g functions" marked in blue on the same keys. Hitting f then - intermediate results. This stack is used a key is one function. Hitting g then a key is another. This with the "enter" key. Suppose, for ex- gives many functions with few keys. ample, we want to calculate (5 + 3) X (7 + 9). The steps would be

62 ELEMENTARY ELECTRONICS /September -October 1977 www.americanradiohistory.com dB -what does that mean? Well, 20 dB appears on the display. You subtract either just means 20 = 10 log R where R is the 1, 2, or 3 from the number. The calcula- ratio of the new sound level to the old tor then selects (via its program) whether and "log" is the logarithm function. To to subtract 1, 2, or 3, then executes that find R, place 20 in the X register, divide subtraction as the display changes auto- by 10, press the yellow "f-t" key, then the matically. Then it is your turn again. The "log" key to get antilog (2) = R or R player (you or the calculator) reaching = 100. So the noise will be cut by 100 zero first loses. If the computer wins, it times. writes 55178 ( "BLISS" upsidedown); and Mathematics. The trigonometric func- if it loses it writes 3507.1 ( "I LOSE "). tions in the HP -65 are sine, cosine, and From all of the above discussion you tangent. These allow you to figure out the must have rightly gathered one main point length of sides of triangles when the an- -programmable calculators can do a lot. gles and one side are known. If, for Now answer this question: Which, in example, the shadow of a tree is 40 feet general, is more powerful and more flex - long and the sun rays make an angle of ible-a calculator or a microcomputer? 30° with the ground, the HP -65 will show The answer is a microcomputer. In fact, you that the tree is 20 feet tall. There is a a calculator is really a specialized micro- function that converts from octal code - computer where the various functions like the very numbering system many micro- sines and logarithms have been writteñ as computers use (remember, in octal, 07 is 7 equations and pre -programmed onto ROMs in decimal, 10 is 8 in decimal, and 11. is inside the calculator. If a microcomputer 9) -to decimal code or vice- versa. This has sufficient memory, you can program conversion function is made to aid com- it to do anything a scientific calculator puter programmers. The square (x2) func- can do and more, but you cannot get a tion on the HP -65 is useful in many equa- Texas Instruments announced a new line of calculator to do all that a microcomputer tions but if some other power is needed programmable calculators just as this issue can do. A microcomputer can be made to besides 2, the calculator has a "y to the went to press. Above is the TI 57 ($79.95). accept input data lines and to pulse data x power" function, where you specify any This is a new, scientific programmable de- out to a teletype or to a control device; y and any x. There is also a factorial func- signed with the student user in mind. it can control your model railroad; keep tion, which sounds fancy but is easy to Rather than a simple instruction manual, inventory of your supplies and automati- understand. If there are four horses in a which can be confusing to many first -time cally write orders; play complex games race, it turns out there are 24 different users of programmables, the 57 is complete like chess; and even generate sounds or ways they can be lined up crossing the with the book "Making Tracks ." tones through a speaker. A pocket calcula- finish line, where, for example, 2 - 1 - 3 tor cannot do those things simply because - 4 is one way. The number 24 comes ber (4, 8, whatever) in the X register and it is not designed to. Convenience is the from 1 X 2 X 3 X 4= 24 and the expres- press the "n!" key. How long would it keyword. A press of a key gives a pre- sion 4! (called four factorial) is just an take you to calculate 69! ? A calculator programmed function, whereas with a abbreviation for 1 X 2 X 3 X 4. The HP- does it in about two seconds. microcomputer you have to write that pro- 65 calculates factorials. Just put your num- Programs. Programming a pocket calcu- gram into memory and then you can use a lator basically means one thing -a sequence single key to access it. With a microcom- of key stroke instructions are stored in puter you have essentially unlimited po- the calculator's memory. When you want tential but you have to build all the to run the program, you press the start programs into it. Tune in next month key and the calculator runs through its for more micro mania. memory of key strokes performing each function as it goes. You can imagine the stored program causing an invisible hand to be working the calculator keys in exactly the proper order to perform the calculation you need. Why have a programmable calculator? Because by putting the program in the calculator once, you can use it again and again with different numbers as inputs. Suppose, for example, you want to manufacture electronic games by special order and you have worked but a formula to give the prices you must charge your clients based on the number of integrated circuits in the game he wants built, the size of the order, the delivery date, etc. By programming the equation into the calculator, a price quote can be given to the client without having to go through the long formula each time. Both the HP -65 and HP -67 accept pre- With the HP -65 (or HP -76, or SR 52) the recorded programs via magnetic cards. program can be stored on a magnetic strip The cards are fed into a slot on the side for use at any later time. Hewlett- Packard of the calculator and are pulled through and Texas Instrument have written many The TI 59 ($299.95) represents a new ad- by a motor. The user may also record useful and fun programs onto magnetic vance in hand -held programmability, due his own programs onto blank tapes. This strips you can buy from their program to what Texas Instruments terms a "library system allows programs to be saved and library. One typical fun program is the module." A library module is a plug -in IC filed for later use so the calculator game of NIM wherein you play against chip which can contain up to 5,000 pro- doesn't have to be programmed over the calculator. After inserting the programmed steps -more information than can and over again. gram via the magnetic strip, a number be recorded onto 25 magnetic cards.

ELEMENTARY ELECTRONICS /September- October 1977 63 www.americanradiohistory.com £Dfl1FUTEF PPiEJIJLJCTS Here in one place each issue of e/e you will find product information on the newest hobby computers and accessories.

Auto -Boot Loader -RMQ Systems says the company's Power -Start auto -boot loader frees you from ever keying in a bootstrap program again. The simple action of pressing RESET on the front panel automatically loads your computer from your loading device -disc, cassette, paper tape or other medium. The device is compatible with the Altair 8800, and allows it to be run without the front panel. All that is needed is an ON /OFF switch and a RESET button. Power -Start is available as a complete auto -load board, with its own ROM, or it can be purchased without the ROM and used with your own ROM or PROM memory. It can be configured to execute a loading program located anywhere in your memory address space. Rewiring of your computer is not required; just plug into the backplane, like any other board. An on -board switch permits disabling of the board. Power -Start is DC Power Supplies -Adtech Power offers available in two kit forms and two assembled versions: Model PS-1K is priced at four TAPS Series triple output DC power $195; model PS -2K, the kit without ROM, is $165. Assembled model PS -1A costs supplies for microprocessor and other $295; model PS -2A, also assembled but without ROM, is price- tagged at $265. RMQ multiple DC power applications. All three Systems, 1044 University Ave., Berkeley, CA 94710. Circle 50. outputs are isolated from each other so that either positive or negative can be grounded on any output. Adjustment of Keyboard Encoder -Radio Shack now output voltages is accomplished by means stocks an ASCII Keyboard Encoder that of screwdriver adjust isolated wire -wound utilizes the Shack's exclusive "Project - potentiometers. The units are constructed Board" concept. You purchase the on an aluminum chassis with approximate- printed circuit board with a complete, ant 11I11111111110 ±lwrrr ly 20% more heat sink area than on com- step -by -step assembly instruction manual Ar9!!11l111**1111}Plrwls. petitive units, according to Adtech. All for as- and parts list. All necessary parts !*1l111111'1l1rl14lr 1R,: units may be mounted in various orienta- sembly of the encoder, including a 63- tions with various optional fasteners. Over - key computer control keyboard, are avail- voltage is included in all units on the 5V able from Radio Shack. Or you may use outputs, and foldback current limiting is parts from your own "junkbox" collection. The encoder can be used with TV type- standard for all three outputs. Remote writers, minicomputers, microprocessors, electric typewriters, or any other devices sense is also provided on the 5V output. requiring positive or negative ASCII encoded alpha -numerical characters. Features DC outputs specs and prices: TAPS 1, 5V to and include: repeat key control all characters symbols; negative -going or @ 4A, ± 12 -15 (a 0.5A, $94.15; TAPS 2, 5V last key and positive -going data valid strobe; latch outputs (stores code); shift shift @ 6A, ± 12 -15 cßì 1.0A, $107; TAPS 3, lock capability; true or false ASCII outputs; six extra control keys. The encoder 5V @ 9A, ± 12 -15 1.5A, $137; TAPS 4, handles an a 208 output of 833 characters per minute and has repeat key rate of 5V @ 12A, ± 12 -15 (i 3.0A, $163. Units are CPM. An external power source of 5 VDC at about 500 ma is required. The project also available ± 9 -12V as an option. Other board with complete assembly and parts manual costs $14.95. All parts needed to specs: regulation, =0.1% for line and load assemble the encoder, including the circuit board, manual and keyboard, but ex- with universal input of 115/230V ± 10 °%o, cluding hardware and case, are available from Radio Shack for $57.80. Radio Shack, 47 -62 Hz; ripple, 5mV peak to peak maxi- 2617 West 7th Street, Fort Worth, TX 76107: Circle 32 on Reader Service Coupon. mum (typically 1mV); stability, ±0.2 °/o; transient response, less than 50 micro- Super- Compact Computer - Microcom- seconds. Adtech Power, Inc., 1621 South computer Associates' Super Jolt is one Sinclair Street, Anaheim, CA 92896. Circle of the most compact single board com- 60 on Reader Service Coupon. puters available. It measures 41/4" x 7" and contains an 8 bit 6502 microprocessor, 1,024 bytes static RAM, 32 bidirectional and programmable I/O lines, a 1 megahertz crystal controlled clock, an interval timer, 4 interrupts including a timer interrupt and a non -maskable interrupt, three serial interfaces. The system includes a 20 ma current loop, RS232 and TTL, as well as 5,120 bytes of resident ROM program memory that includes a complete single pass Resident Assembler Program called RAP, a resident TINY BASIC interpretive language designed especially for JOLT systems and the 1,024 byte DEMON DEbug MONitor program. Super Jolt can function as a single card development system permitting assemblies to be Floppy Disk -OSI's 470B floppy disk, an made with only a single pass of a source program from a terminal or via a TTY upgrade of the company's popular 470 paper tape reader. Programs can be debugged, and higher level language can be model, features a GS! model 110 disk drive used. Single unit pricing for the Super Jolt card, fully assembled and tested is $375 for 240K bytes single density storage. without RAP and TINY BASIC ROMs, and $575 with the ROMs. Microcomputer There's also a head load indicator and a Associates, 2589 Scott Blvd., Santa Clara, CA 95050. Circle 55. (Continued on page 101)

54 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com o flEW PRODIDUCTh e/e puts together in one neat package some of the newest CB rigs, r 1 antennas and accessories for you to use in CB contacts this year!

CB Filter System Calibration marks permit the user to return CB Mobile Converter The NFS -1000 Noise Filter System from Spark - to any previously determined setting. Priced Car radios can easily be converted into CB omatic for use with CB transceivers and AM at $46.50. For further information, write to receivers with the CB /AM Converter by GC and FM radios, is a unique combination of Mura Corporation, Westbury, NY -1590. Electronics. Tune in any of the 40 CB chan- filters designed to eliminate interfering noises nels with an ordinary car radio. The CB /AM from all vehicular sources including ignition Co- Phased Antenna System Converter works from any car antenna, in- spark, alternator /generator, other accessor- Designed especially for trucks. motor homes cluding windshield types. It's an ideal way ies, metal to metal contact. The unit effec- and recreational vehicles, and operable on to be advised of road and weather conditions. tively reduces noise levels without impairing all 40 channels, Avanti's AV -529 CB Antenna No license is required to operate the con- engine performance or power. NFS- 1000's system consists of two 4 -ft. fiberglass Avanti verter. The AM radio reception is unaffected special features are the dual line noise Racer antennas in a co- phased arrangement. This arrangement increases performance approximately 25% over a single roof -mounted antenna, and minimizes the problem of a

CIRCLE 65 ON READER SERVICE COUPON when the converter is switched to the Off CIRCLE 74 ON READER SERVICE COUPON CIRCLE 73 ON position When in the On position, the red designed to filter the power line and READER SERVICE filter LED indicator light goes on. Hardware and COUPON eliminate residual noises. Accessories such complete instructions are supplied. Installa- as mechanical voltage regulators and electric tion is simple. Sells for $19.95. GC Elec- fuel pumps produce interference in the form tronics, a division of Hydrometals, Inc., of- of an irregular "frying" sound. The filter con- fers a complete line of CB radios, antennas both low high tains and frequency filtering and accessories. Get all the facts, by writing circuits and is generally effective at these to GC Electronics, 400 South Wyman, Rock- all Also and other disturbing frequencies. in- ford, IL 61101. cluded are: an ignition noise suppressor, alternator noise filter, and generator noise New Hide Away Antenna filter. The NFS -1000 sells for $15.95. Get all The Hustler Hustloff Instant -Removal, store - the facts from Sparkomatic Corporation, Mil- skewed or shifted radiation pattern. The in- the -trunk, instant- remount antenna has per- ford, PA 18337. mounting assembly fits most mirror bracket formance equal to any permanently mounted arrangements including west coast types. It is mobile installation! The special design trunk readly removable for easy transfer to another lip mourt firmly clamps to any trunk lid with Twin Scale CB Meter vehicle if desired. The co- phasing harness, the twist of a knob. Operation is instant and Here comes Mura's Model CBM -30 meter. A completely factory tested to assure maximum easy. Positive grounding is assured with the twin meter unit, there are separate power and performance, connects quickly and easily to heavy duty, case -hardened clamp assembly. SWR scales permitting simultaneous monitor- the mirror mounts. Priced at $53.95. For Mounted antenna cannot be removed when ing of RF output power and VSWR. The meters more info, write to Avanti Research & De- are sensitive d'Arsonval types with an SWR velopment, Inc., 340 Stewart Ave., Addison, scale that has a range extending from 1:1 to IL 60101. 10:1 and can measure up to 100 watts with a plus -minus accuracy of 20 %. The CBM -30 CB Noise Suppression Filter ON has an input and output impedance of 52 The EMI -TVW2 is an improved twelve -element CIRCLE 72 READER SERVICE ohms and so does not disturb the impedance low -pass TVI filter for CB base stations. In COUPON of the connecting coaxial cable. The unit can practice, the harmonics of a 1 -kW, 28 -MHz ham transmitter are held to 20 dB below the

trunk is closed. Deluxe features include a CIRCLE 49 ON READER SERVICE COUPON CIRCLE 46 ON READER 180-degree swivel for positioning antenna be permanently installed between the cable SERVICE COUPON to optimum vertical location, 17 -ft. coax with and the input to the transceiver with minimum connector factory attached. The Hustloff is insertion loss. By having a permanent instal- available with 48 -in. standard and 55 -in. heavy lation the CBer can constantly monitor power minimum useable TV signal. Even better per- duty stainless steel antennas for 40- channel and SWR to make sure that the transceiver/ formance is realized in the CB band. Insertion coverage. Priced at $28.95 for the HT-27 and antenna combination always supplies optimum loss is under 0.4 dB below 30 MHz. Sells for $31.25 for the HHT -27. Additional informa- RF power output. No switching is required and $16.95. For more facts, write to Marine Tech- tion may be obtained by writing to New - both meter pointers are controlled by a con- nology, 2780 Temple Avenue, Long Beach, Tronics Corporation, 1580 Commerce Park tinuously variable knob on the front panel. CA 90806. Drive, Brookpark, OH 44142. ELEMENTARY ELECTRONICS /September- October 1977 67 www.americanradiohistory.com by Kathi Martin, KGK3916 Hathï's CB Carousel Kathi -now a TV star -checks out the E. F. Johnson Messenger 92

Ah yes! I remember them well. CB cifically, the E. F. Johnson Messenger the rear cover, as shown in the pho- walkie-talkies I could actually push 92 hand -held. tographs. In normal use this type of down in the pocket of my jeans and Pocket Power. Look at the photo of rechargeable pack can take between still slide into the seat of a ' vette. Only the Messenger 92. Anything look 500 and 1000 charge- discharge cycles. problem with the pocket -sized hand - strange? Right! The antenna is only a Because there's no wasted space be- helds was the under -100 mW input bit longer than the case -93/4 -inches to tween cells the 92's battey contains a power barely got the signal down the be exact. It's really a rubberized flex- lot of energy in a relatively compact block, let alone to the next campsite; ible antenna -often called a rubber case, so the overall weight of the hand- but for short-range communications ducky-the same type of antenna used held is sharply reduced. Note, also, they were great -as long as you took on the over -$1,000 police /fire hand - there's no connecting wires between the care not to spear someone's eye with helds. Now look at the size of the case battery section and the transceiver it- the extended antenna. in proportion to the hand-which be- self. Two pressure contacts at the top To push the signal out farther hand- longs to one of the techs in the tèst of the battery automatically make con- held power was increased to 1 -watt, lab. Note how the Messenger 92 actual- nection to the transceiver when the 2- watts, 3-watts, and would you believe, ly fits the hand, just like a police fire/ cover is secured with a single captive even 5- watts. The package got bigger unit. Aha! You think Kathi is pulling mounting screw. and bigger, the spear when fully extend- a fast one and the Messenger 92 isn't User -Programmed. As for features, ed got loner and longer, and the Nicad a CB transceiver. Wrongo! The Mes- the Messenger 92 is user -programmed batteries usually needed for extended - senger 92 is a CB hand -held, but it has for up to five channels using separate, time full -performance made the hand - the convenience features of police /fire and inexpensive (standard) transmit helds heavier than an SSB mobile rig. models. and receive crystals. The crystals plug As long as there was nothing better To start, the Messenger 92 is about into the small strip holder near the top we had to put up with the oversize and the size of the hand -helds you see that's exposed when the battery cover overweight hand -held because that was tucked into the hip pocket of your local is removed. An aluminum write -on la- the only way we were going to get high - beat cop. Similarly, instead of being bel on the back of the battery cover performance in a mini- package. But loaded with ten or twelve Nicad AA allows you to indicate what selector now as they say in the TV commer- penlight batteries the 92 has a special- position is which channel. cials, I've found the better way. Spe- ly shaped Nicad that occupies most of The channel selector is located with the volume and squelch controls on the top, along with a screw -jack for the CRYSTAL PUSH -TO -TALK rubber ducky, micro -mini jacks for an SOCKETS BAR external antenna and remote speaker, and a battery- saving LED battery con- Unlike the typical CB dition indicator. Under normal condi- hand -held that uses ten tions -when the battery charge is up- or twelve penlight Nicad the LED is off, so no extra current is batteries the Messenger SPEAKER being used telling the user the battery 92 has a special Nicad is okay. When the battery charge is shaped to fit the cover, reduced through use to the point where thereby providing the you had better recharge soon or you'll most power in the small- be talking to yourself then the LED possible space at a est -mini sharp reduction in over- lights. Unlike the mini LEDs used SEALED on some rigs which can barely be seen all weight. The crystals - JOHNSON NI CAD which are user selected- CELLS at night let alone in daylight, the LED plug into a strip near the The supplied battery charger plugs into a top of the main section. CAUTION charging jack in the bottom of the case. m et 41,11011( It is a trickle charge, taking 10 to 16 hours for a complete recharge, but the low rate allows the charger to be left connected without worry about damage to the battery.

68 ELEMENTARY ELECTRONICS/September-October 1977 www.americanradiohistory.com CHANNEL SELECTOR The three controls mount- EXTERNAL ed on top are for vol- BATTERY ANTENNA ume, squelch and chan- INDICATOR nel selection. (The 92 REMOTE SOCKET FOR handles up to five chan- SPEAKER "RUBBER DUCKY" nels.) The rubber ducky ANTENNA antenna screws into the antenna socket. Micro - mini jacks are provided for an external antenna and remote speaker. An VOLUME JOHNSON Messenger 8:. SQUELCH LED battery condition indicator lights only when the battery is starting to run down; it is off when the battery has a substantial charge.

dB. This is good even when compared in the next production run. Otherwise to many high -priced double conversion you'll be totally impressed with the 92. models and is more than adequate for The Messenger 92, supplied complete hand -held use. Overall sensitivity with with Nicad battery and external charger the signal generator connected to the is priced at $169.95. Crystals are op- antenna input jack measured a hot 0.3 tional. No, that's not a police /fire hand -held, it's uV for 10 dB S+N /N (signal plus For additional information circle No. Johnson's new CB Messenger 92 which noise to noise) ratio. 47 on the reader's service coupon. comes complete with a short rubber ducky In Actual Operation. The Messenger antenna. The thing really does fit inside a 92 proved to be a real winner. The re- pants pocket. ceive and transmit sound quality is ex- ceptionally good, very crisp and clean indicator on the Messenger 92 is rather -a signal easily heard over ambient large and can be seen under typical noise. Naturally, the short rubber ducky sunny skies. antenna does not radiate as efficiently Because separate crystals are used for as the longer spear type telescopic transmit and receive the circuit is about whips, but if you're not trying for five as straightforward as you're likely to miles range from a hand -held the Mes- find anywhere: something I like in senger 92 holds up well. The nice part portable equipment because the fewer is if you tuck the 92 in your jeans or the number of circuits and parts the clip it to a belt the antenna doesn't jab less likelihood there is something will you in the ribs, it simply bends out of break down when least expected. the way and then snaps back. It also The Crucial Figures. The transmitter doesn't stick in someone's eye. uses but three transistors to produce Overall, I'm much impressed by the 1.9 watts output at the antenna jack Messenger 92. My only gripe is the into 50 ohms. Modulation is limited to micro -mini jacks for the remote speak- 100% and the microphone sensitivity is er and particularly the remote antenna. -21 dB- exactly average. It's very hard to locate a micro -mini to Kathi Martin, along with other not- The receiver is single conversion UHF adaptor plug, and the micro-mini ables in the CB field such as Jon with a bandpass filter providing a meas- plug is a bit small for most coax cable. Gallo, Phyle Home, Leo Sands and ured adjacent channel rejection of 58 I hope Johnson changes to mini -jacks others, took part in the filming of an i NBC Knowledge Series on Citizens Band Radio. Unfortunately, when you read this notice, the first airing would have taken place, August 1 through August 5 on KNBC in Los Angeles. Programming information for the Chicago, Cleveland, New York and Washington (D.C.) areas are planned but not firmed up at this

time. Also, almost all NBC affiliates E will repeat these TV- casts. We sug- 3 gest you call your local TV station E carries NBC programming to ithat 1 obtain dates and times of the Know- E É ledge Series on Citizen's Band Radio. -The Editor

ELEMENTARY ELECTRONICS /September- October 1977 69 www.americanradiohistory.com CAM ERA` FI TO DECA

Ultra- violet camer, gets to the roo of decay.

"An ounce of prevention is worth a instant photographs of a paient's teeth, pound of cure." This age -old adage so that the areas of plaque would be seems to be the personal motto of Dr. highlighted for the dentist's use. Israel Kleinberg, the chairman of the Now, a camera of this sort has been dental research team at the State Uni- perfected and has been in use for one versity of New York- Stonybrook. Dr. year at Stonybrook University. A small Kleinberg has been developing ways of tube at one end of the camera houses preventing tooth decay since 1955. In a lens. After an initial thorough clean- hopes that eventually drilling & filling ing of the teeth, the camera is used to teeth will rarely be necessary. check for persistent areas of plaque. A Dr. Kleinberg's decay prevention sys- patient's lips fit around the tube and a tem is based on the fact that 90 percent picture is taken of the patient's clenched or more of all tooth decay is the result teeth. The instant picture shows the of "plaque." Plaque is a protein film plaque areas which are then treated and that builds up around the teeth. Plaque cleaned again. A second picture would At top right the camera's developer, Dr. harbors bacteria which eat into the tooth hopefully reveal that all the plaque has Gwinnette, changes the front lens attach- enamel and causes cavities. Thus, keep- been removed. Any remaining stains ment, which varies according to the shape ing teeth plaque -free would prevent would indicate that a cavity had begun of the patient's mouth. The front lenses are decay from setting in. to form. completely interchangeable, and attach to an internal There was one crucial problem which Dr. Kleinberg and his research team the main unit by means of Dr. lsreal Kleinberg (at right) assists Dr. Kleinberg had to solve: under nor- feel that in the future this sort of equip- clamp. in the process. In the middle right photo- de- ment will be used widely to prevent mal' conditions plaque is not easily graph, the side view of the camera is tooth decay from occurring in the first tected by the human eye. Under ultra- shown as the two doctors discuss its opera- his violet light however, plaque is easily place. Under other circumstances tion. At the rear of the camera the polaroid visible as a darkened area which stands work might be recognized with an film attachment, which allows instant de- out from the rest of the plaque -free honorary plaque, but since he's dedi- velopment of the photographs, can be enamel. After making this discovery, cated to plaque -prevention, some other seen. Bottom right shows the plaque cam- Dr. Kleinberg & his research team set sort of trophy would probably be more era as it is directed toward the mouth of out to build a camera which could take appropriate. a patient.

70 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com LOUE AND CLEAR GOOD CIRCLE 32 ON CIRCLE 59 READER SERVICE ON READER BUDDY! COUPON SERVICE COUPON

Keep your hands free for better things than holding a microphone, but still keep in touch with your CB Buddies using the CB -88 from Telex. This headset can be CIRCLE 48 ON worn from a headband or can be dipped READER SERVICE This Realistic 21 -1171 mobile preamplifying COUPON onto the user's eyeglass frames. It weighs mike offers variable gain to 25 dB; a less than three ounces and comes in dB; a sensitivity of -42 and comes with different versions to match all CB four -conductor cable. $19.95. transceivers. $69.95.

CIRCLE 44 ON itt READER SERVICE COUPON Superpunch! That's CIRCLE 49 ON Shure's name for this READER SERVICE handsome microphone. It includes such COUPON features as a "million cycle" leaf-type, press -to -talk switch and the capability of 44% being used with Voice Operated Relay (VOX) transceivers. $42.

e/e looks and listens tc CB power mikes Turner's Expander 500 mirophone would be at home on the bridge of the starship Mura's PRX -300 offers their PRM (Peak Enterprise, or next to your favorite CB Redistribution Modulation) feature, a by Jorma Hyypia transceiver. This futuristic design includes "distortion- limiting" extra. The futuristic separate volume and tone controls, and a design houses a mike of 28 dB gain, meter which measures both audio input and variable impedance and -36 dB sensitivity. battery strength. $65. It requires a 9 -volt battery. $60.

"Come back ?" out by your CB set; but it can load miracles? A tiny battery- powered am- If you keep hearing that request from your carrier wave with more audio in- plifier built into the mike strengthens your modulatin' Good Buddies, al- formation, and do it with less distortion, the audio signal before sending it to though you talk as clearly as a Shake- than is possible with the cheapy mike your CB transceiver. Thus, the trans- spearean actor, it can mean but one that came with your CB set. As much mitter has more to work with and can thing; your CB rig just isn't putting as 35% of the potential information - more easily put out a fully modulated out as clearly as you are putting in. carrying capacity of your carrier wave carrier wave. This can be overdone. But, forsooth, don't make haste to may now be wasted. By packing more Overloading results in distortion, which junk your transceiver, which might be audio into it, your speech will sound is why the better power mikes have a perfectly good; the varlet garbling your clearer -albeit not louder -even to those volume control that permits you to speech may only be the original equip- reading your mail out at the fringes of adjust the carrier loading right up to ment microphone that came with your your CB range. The end result: it seems 100%, but no more. CB set. Replace it with a power mike that you are getting better distance. The following market survey will get and you will start hearing bounteous Certainly, improving your reach by you started on your hunt for just the praise for the quality of your audio, clarifying your speech makes more right power mike. Your local plealer instead of those wearisome "Come back sense than adding an illegal linear amp- can provide more detailed specs. If pos- again" pleadings. lifier just to splatter unintelligible audio sible, test several power mikes on your A power mike will not (and should further around the landscape. own rig while a friend modulates with not) actually boost the RF signal put How does a power mike work such you from the other side of town. Pick

ELEMENTARY ELECTRONICS /September- October 1977 71 www.americanradiohistory.com by an omnidirectional dynamic element M -606 ($35) is similar to the M -607 are amplified to provide adjustable out- but lacks the variable gain control. I I LOUD AND CLEAR, GB put levels from 0.63 to 14mV for 1 Superex also offers a VOX -type base microbar input. Other specifications station microphone, model M- 606VX, the one that makes your speech easiest are: Frequency response, 200 to 6000 selling for $110 complete with "Vox - to understand. Hz; output impedance, 5000 ohms; load Box" control. We'll consider three different cate- impedance, 500 ohms; cable type, 3- Turner is out to tempt you with a gories of power microphones: (1) Base conductor shielded; power source, 9- broad selection of base station mikes, mikes that have integrated stands to volt battery. including the Expander 500 which re- hold them upright on a table, (2) hand- Shure's Model 444T preamplified tails for $65. This really jazzy-looking held Mobile mikes and (3) Hands -Free base station mike ($37.50) has a vol- job sports separate volume and tone mobile jobs. Let's take them in that ume control, and a push -to -talk bar controls, an audio input indicator meter order. with an optional lock. The height of as well as a battery strength meter, Incidentally, manufacturers of com- the pickup head is adjustable. Specs: press -to -test button to check the bat - munications mikes often stress the rela- Frequency response, 200 to 6000 Hz; ery, adjustable tilt head and a press -to- tively limited frequency ranges of their impedance, less than 1009 ohms; output talk switch with slide lock for extended microphones. This might seem puz- level, adjustable from 2 mv to 45 mv transmissions. The Expander 500 util- zling to hi -fi audio fans until it is re- for I microbar input; comes with a 4- izes a dynamic cartridge and is pow- membered that these mikes are intended conductor cable. ered by a 9 -volt battery; maximum out- for voice reproduction. Suppression of The Superex model M -607 ($45) is put level is -30 dB, and the output im- frequencies outside the normal voice an electret condenser type base station pedance is 5000 ohms; comes with a range can be desirable in order to mini- microphone with a preamp powered by 5- conductor cable. mize background noises. one AA battery. The mike features an Turner's model CS-1 base station Base Mikes. Mura offers two base adjustable gooseneck support, variable mike, listed at $85, was designed station power microphones that have gain control, interlocking push -to -talk for transceivers requiring 6- conductor housings of decidedly "modern" styling. switch and 500 ohms impedance. Model cables and special switching. The ceram- The Model PRX -300 retails for $60, and the DX -2000 for $50. The specs on both microphones are: Sensitivity, -36 dB; gain, 28 dB max.; impedance, variable to 2500 ohms; switching, relay or electronic; color -coded, 5- conductor cable. They both feature slide -type CIRCLE 44 ON gain control, push -to -talk and lock READER SERVICE switches, and a dynamic amplifier COUPON powered by a 9 -volt battery. The PRX- 300 adds Mura's PRM feature. The letters stand for Peak Redistirbution Modulation, and Mura maintains that this patented circuit results in less distorted modulation. Every Good Buddy wants a sidekick -and CIRCLE 48 ON READER SERVICE COUPON Radio Shack their offers Realistic maybe the Super Sidekick will do. An Shure's Model 524C Ranger 2 is a cute little brand 21 -1173 base station microphone adjustment in the base allows for its handful. It features a transistorized amplifier ($29.95). The maximum variable out- impedance to be matched to either tube- claimed to have enough oomph to permit put of the mike is 25 dB; sensitivity, type (high- impedance) or transistorized use of a 100 feet of unshielded cable. It -42 dB; impedance of 3300 ohms; and (low impedance) sets. The neck and base requires 2.5 to 35 VDC and uses a switchable for electronic or relay opera- are jet black, the head is chrome. $58. 4- conductor cable. $66. tion. It requires two AA batteries. Primo offers a model DM- 1524A1 base station mike retailing for $55. It has a transistorized preamp, gain control lever, switch locking lever and push -to -talk switch. Inside the case there's a changeable switch for relay and electronic switch wiring; either a 3- conductor or 5- conductor cable may be used. This dynamic cardioid job has au output level of -40 dB and an output impedance of 100 ohms. The Shure Model 526T Super Punch CIRCLE 45 ON CIRCLE 59 ON base station mike ($42) has a lockable READER SERVICE, READER SERVICE "Million Cycle" leaf -type press -to -talk COUPON COUPON switch, a modulation level volume control, and a Normal /Vox selector switch Telex's CB -73 is a power and noise - for press -to -talk or for use with VOX - RMS Electronic's CMB -5006 is powered from canceling mike all in one. It features operated transceivers in which the a 9 -volt battery. It has a two -position gain "aviation" styling and an unspecified sound of the operator's voice triggers control and 20 dB gain. $29.95. amount of variable gain. $39.95. the transmit circuit. Sounds picked up

72 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com is generating element is unaffected by Mobile Microphones. The hand -held three separate levels that are user ad- temperature or humidity. The 9 -volt microphones discussed in this section justable. Both use a 9 -volt battery, a battery usually lasts about 6 months. can be used with base station equip- 5- conductor cable, and have relay or Specs: Sensitivity, -23 dB; output im- ment if you do not dig the larger stand- electronic switching capability. The pedance, 5000 ohms; amplifier voltage up models. However, we list them under DX -116 specs include: Sensitivity, -42 gain, 0 to 33 dB adjustable; Frequency "mobile" equipment because most dB max.; gain, 20 dB max.; variable range, 300 to 3500 Hz. Model +3B is CBers will buy them for that purpose. impedance to 2500 ohms. The DX -120 identical to the CS -1 except that it has Mura's model PRX -100 ($40) offers specs: Sensitivity levels, -54 dB, -45 a black finish instead of a gold housing. variable gain controlled by a slide dB and -43 dB; gain settings, 23 dB, Turner's model +2 is a ceramic mike switch. The maximum gain is 16 dB, 21 dB and 12 dB; nominal impedance, with battery- powered preamp, a volume and other specs include: Sensitivity, 2000 ohms. selector controlling 0 to 30 dB gain, -50 dB; impedance variable to 2500 The Primo model DM -1618 mobile and a slide switch to adapt the unit to ohms. The PRX -100 is powered with mike ($40) features a gain control relay or electronic switching. Uses a 9- a 9 -volt battery, uses a- 5- conductor lever, slide switch to adapt for relay or volt battery and 3- conductor cable. cable, and has provision for relay or electronic switching, and handy battery Price: $48. electronic switching. inside the battery compartment Other Turner base station micro- By sacrificing variable gain, you can lid. The DM -1618 is available with phones you may want to check out in- get model PRX-200 for the more mod- either a 3- conductor or 5- conductor clude Model +3 ($55) which has a est price of $29.95. It has -58 dB sen- cable and has the following general maximum adjustable output level of sitivity, 7 dB gain, and a nominal 2000- specs: Type, dynamic omnidirectional; -23 dB; also the Super Sidekick ($58) ohm impedance. output level, -40 dB; output imped- which offers up to -25 dB gain plus a Two other Mura mobile power mikes ance, 100 ohms. setting in the bottom of the base to worth investigating are the DX -116 Realistic from Radio Shack prices adjust the mike to requirements of both and the DX -120, priced at $29.95 and their 21 -1171 mobile preamplifying tube -type (high impedance) and tran- $18.95 respectively. The DX -116 offers mike at $19.95. The 300 ohm mike has sistorized (low impedance) sets. variable gain whereas the DX -120 has a variable gain of 25 dB maximum, a sensitivity of -42 dB and uses a four - conductor cable. RMS Electronics offers an amplified mobile microphone, model CMB -5006, selling for $29.95. It operates on a 9- volt battery, has a two -position slide gain control, and provides "20 dB more gain than conventional microphones." A Shure model 524C Ranger 2 ($66) features a transistorized amplifier claimed to provide enough output signal to permit use of up to 100 feet of CIRCLE 44 ON unshielded cable. This dynamic type READER SERVICE CIRCLE 44 ON microphone has the following specs: COUPON READER SERVICE COUPON Frequency response, 300 to 5000 Hz; output level, -44 dB; load impedance The Turner Expander 400 lights up to let The Road King 77 combines preamplification range, 250 to 2200 ohms; maximum you know when its battery is low (a small with noise canceling versatility. Turner calls signal, 118 dB SPL at 1000 Hz pro- light is recessed above the grille). Complete it "the perfect truck microphone." The mike duces 0 dBV (1.0V) at 10% THD. The with a variable gain, the mike comes with is complete with a black mesh screen and DC supply voltage range is 2.5 to 35 6- conductor cable. $45. rubber lip guard. $44. VDC, and a 4- conductor cable is used. Superex pegs the price of its M -508 CIRCLE 48 ON mike at $25, for which you get auto- READER SERVICE matic gain control for signal COUPON equaliza- tion, and compression amplification to prevent overloading. It uses one 7 -volt mercury battery and has an impedance of 500 ohms. Sylvania offers two power mikes with variable gain control, relay or electronic switching capability, 5- conductor cables, and operation on 9 -volt batteries. Model SDX -100 ($40) has the following specs: Sensitivity, -50 dB max.; gain, 40 dB max.; impedance, 0 CIRCLE 44 ON Shure's HF 52 Mobile Communications to 2500 ohms. Model -70's READER SERVICE Microphone is a hands -free job. The SPM ($30) specs: COUPON dynamic mike can be mounted on the Sensitivity, -42 dB max.; gain, 16 dB dashboard, the sun visor or the steering max.; impedance range is variable to The Turner Road King 66 is a variable column. Also supplied is a footswitch. The 2500 ohms. volume mobile mike with a gain of 0 to system can be operated from any 12 VDC Telex says that its CB -73 mobile 15 dB. It can be yours for $42. negative-ground vehicle battery. $99.60. power mike is designed for "aviation standards performance" so it makes

ELEMENTARY ELECTRONICS /September- October 1977 73 www.americanradiohistory.com I LOUD AND CLEAR, GB

sense to package it in an "aviation type acoustic housing." For the list price of CIRCLE 44 ON $39.95 you get a dynamic type, noise - READER SERVICE COUPON canceling mike with -43 dB sensitivity, CIRCLE 48 ON 200 to 6000 Hz frequency response, READER SERVICE and an unspecified amount of variable COUPON gain. Heading the numerically generous selection of mobile power mikes offered by Turner is the Expander 400 which retails for $45. A unique feature is the battery light above the grille lights during trans- which automatically Shure's Model 444T has its ups and downs, If your transceiver requires a [-cable power needs re- mission when the battery due to its variable volume control and an mike, the Turner CS -1 fills the need. placing. The Expander 400 also offers adjustable height feature. Push to talk, with Powered by a 9 -volt battery, the mike a fine -tuning volume control, relay or an optional locking switch, the microphone features a separate locking control and a electronic switching capability, and a comes complete with a 4- conductor cable. ceramic generating element impervious to 6 -wire (5-conductor, one shield) cable. $37.50. temperature and humidity. $85. Expander 400NC ($47) is a noise- cancelling version of the 400 model. Space does not permit detailed description of the many other amplified mobile mikes by Turner. But here are worth checking some model numbers CIRCLE 32 ON out at your local dealer. Model M+3 READER SERVICE ($42) is a ceramic job powered by a 7- COUPON volt mercury battery. Model M+3B CIRCLE 44 ON ($42) offers amplifier voltage gain from READER SERVICE COUPON 0 to 15 dB, and an adjustable output level of -42 dB maximum. Model RK- 66 (Road -King 66) sells for $42 for which you get an adjustable output level to -42 dB maximum, amplifier voltage gain of 0 to 15 dB. Model RK- 77 ($44) offers an adjustable output to -49 dB, and a sturdy wire mesh front screen complete with a rubber Here's the Realistic 21 -1173 base station The Turner +2 has a light blue finish and -a lip guard to help position the mike for mike, with "Glide- Path" gain control. The chrome grill ring. It can be adapted to best noise -cancelling. Model M+2 mike has a push -to -talk switch, a locking relay or electronic switching via a slide ($38) has a rated output level of -40 switch, and a tiltable head. It requires two switch in the base. The push -to -talk bar dB adjustable. Most of these micro- AA batteries for operation. $29.95. may be locked for long transmissions. $48. phones are available in other versions, under different model numbers, for such applications as electronic switching. ing the mike off without noise on the tions Microphone consists of a tiny dy- Hands -Free Mikes. These usually audio line. Specs for the RE51 include: namic mike that can be mounted on a consist of headsets that include ope Frequency response, 60 to 10,000 Hz; car's sun visor, dashboard or steering earphone, but also have the option of impedance, 50 to 250 ohms; output wheel column; an amplifier with ad- a no -hands unit with a mike clipped to level (total including preamp), -54 justable gain; and a heavy -duty corro- the sun visor of the car_ dB; power source, two AA batteries; sion -proof footswitch. The system oper- The top -of- the -line headset unit of- type, omnidirectional dynamic. ates from any 12 VDC negative -ground fered by Electro -Voice is model RE51 If you are turned on by such minia- vehicle battery system. The footswitch which lists for $138 or $139.80, de- ture dynamic headsets, also check out keys the transmitter without disturbing pending on your shipping zone. A very the Electro -Voice 967 series. Model the operator's driving; the transmitter light microphone assembly mounts to 967M, listing for about $93, comes remains on until the switch is relased. eyeglass frames or to a lightweight with one connecting plug for the micro- The frequency range is 200 to 5000 Hz. headband which is supplied. A small phone; model 967ME (about $126) When the mike is 18 inches from the tube, which conducts sound from your uses two connecting plugs -one for the voice source it provides the same out- mouth to the microphone element, is microphone and the other to fit the ear- put as a "close- talked" hand -held job, positioned close to your mouth. A sup- phone jack used in standard private according to Shure. User net price of ple, lightweight cable connects the mike aircraft. the HF52: $99.60. to a separate, small, preamplifier box Shure offers a somewhat different Superex offers a preamplified head- which also houses a muting button type of "hands free" communications set microphone system for $55. Model (cough button) for momentarily turn- system. The HF52 Mobile Communica- (Continued on page 101)

74 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com e/e Cr liUUwig V+Wr

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When the computer bug bytes, this new unit is the right Rx.

CIRCLE 53 ON READER SERVICE COUPON

It seems so easy. Just send for a $1000, but all we have is a system that guage available. Yet another $500 kit box of parts. Spend a few evenings put- could be used only by someone with has a "Tiny BASIC" good for a few ting everything together, and when considerable training in machine lan- small problems and games (games you're all done you have a real com- guage, generally college level work. again) . puter; a computer powerful enough to Of course, most computer advertise- Our Choice. When we were all done equal many time- sharing systems owned ments make it look easy: "Own your we came up with one computer sys- by some small school districts and col- personal computer. Play Star -Trek, Tic - tem (kit) we presently consider a "best leges. The price? Less than that of a Tac -Toe, etc." If you believe a few buy" for the average hobbyist, the decent -not great -high fidelity system. games are worth $1000 or more then Southwest Technical Products Corp.'s Anywhere in the range of less than latch onto any personal computer kit. Model 6800 Computer System. $400 to under $1000. But, if you want to be able to use a The reason we've selected the SWTP Only problem is, a computer by it- computer for serious work without a 6800 is twofold. Firstly, it has a built self can do absolutely nothing. It just degree in computer science, then you in resident monitor that eliminates the sits there on the table. Possibly, it might need one easily and inexpensively need for panel swtiches and lights. You have a row of switches, and lights that programmed in a "higher language." don't need to know machine language wink and blink depending on the oper- BASIC is such a program. A BASIC - to use the 6800; because of the monitor ation sequence of the switches, but for equipped computer and terminal reads you can enter data in hexadecimal form the average electronic hobbyist it's use- out READY when it wants you to directly from the terminal. But even less. There must be some way to talk enter information. BASIC allows even more important, SWTP has a really to the computer, and for that we need a children to build simple programs such excellent 4K BASIC interpreter that in- terminal, an input /output device -or as A + B = C. It allows the electronic cludes multiplication and scientific nota- I/O as it's more commonly termed. hobbyist to program for reactive induc- tion (a rarity in 4K interpreters) and Cheapest I/O is a CRT video display tance -XL= 6.28(f) (L), and then an outstanding 8K BASIC -one of the terminal for about $400 in kit form, runs a hundred or so values of f or L very finest with exponentiation, direct $550 wired. Now we're up to at least in a minute. In fact, BASIC is the peripheral equipment address, patching, beginner's language, the one you see etc. The 8K program contains a whole people using that asks: "What is your slew of operations and commands not name ?" The language that talks to the user. Since we at e/e figure our readers will join the personal computing explosion - which many expect to be as big as CB in the next few years -we surveyed the marketplace for a computer system suitable for the typical hobbyist and student, something that could be used for general experimentation, or for school or business problems other SWTP's table -top "black box" microproces- than electronic. First thing we dis- sor computer and a terminal are all that's covered, is that a lot of money buys needed for a personal computing system. little in the way of easy operation. One The "mother board" and the power supply Simply press the white reset button on the computer kit has a $200 charge just are mounted on the cabinet's base. All front panel and you can program for directly the BASIC interpreter (the computer other circuits plug into the mother board, from the terminal -in this instance a with language program). Another kit priced wiring automatically completed by model ASR 33 TTY. the mother board's PC foils. in excess of $500 has no higher lan-

ELEMENTARY ELECTRONICS /September- October 1977 75 www.americanradiohistory.com a microprocessor /system board, a 4K move on to another package. (All the memory board, and a serial control in- components are not jumbled together SWTP 6800 COMPUTER - @/I@ terface board that can he programmed a welcome variation on the kit pack- for either a 110 baud TTY or a 300 aging we've been getting from the found on some slightly older time -share baud CRT terminal. The power supply "biggies" the past few years.) BASIC systems. The 4K and 8K BASIC components mount directly on the base Warning. SWTP does not supply interpreters for the SWTP 6800 com- of the "black box" cabinet. As as- sockets for the ICs; they specify the ICs puter are available on TTY tape and sembled by the user, the mother board should be soldered to the PC boards. cassette from about $5 to $20 depend- can accommodate five additional 4K Whatever you do, don't make this fool- ing on the program and its base (paper memory boards (under $100 each) for ish mistake. USE SOCKETS FOR tape or cassette). Though there are a total of 24K of memory, and seven EVERY IC. If you wind up with a de- other 6800 type computer kits avail- more interface boards for a total of fective IC (as we did), or intáll an IC able, it's SWTP's BASIC programs that eight peripheral I/O devices such as backwards (which is very easy to do) makes the SWTP computer our "best line printers, recorders, etc. You simply you'll make hash out of the board try- buy." plug in the optional memory or inter- ing to remove the defective or reversed Before going further, let's explain the face boards IC. A complete set of sockets for the whole bit about 4K and 8K memory Construction. The PC boards are basic 6800 computer kit is available systems: The "K" stands for a thousand first quality, and the ICs had a notably from the Computer Mart of New York, bytes -eight bit "words." A computer excellent failure rate -only one was de- 118 Madison Ave., N.Y., N.Y. 10016, with 4K memory RAM (random access fective. This, considering the large num- for $23 postpaid. They also have memory) can be programmed up to, ber of ICs supplied, is excellent. (We socket sets for the optional SWTP com- or has the capacity for, 4000 bytes. An have come to expect up to a 10 per- puter boards (such as additional 4K 8K memory means 8000 bytes Theo- cent IC failure rate in kits.) To suc- memory boards). retically, 4K BASIC should fit into a cessfully build this kit you must use a Do not handle any IC unless you're needle pointed soldering iron rated grounded just as specified by SWTP. about 25 watts. Anything larger will They even provide a 1- megohm resistor result in solder bridges -the printed foils so you can "safety-ground" from your are unusually close compared to the wrist to the electrical ground. A wire usual hobbyist kit's printed circuit to the ground bus or chassis of the board(s). Also, you must have someone computer is not a ground. You must well skilled in computer technology be grounded to the electrical ground. willing to help you debug the system; Any tool or knife used near the ICs we'll explain the need for this later. must be grounded. While not all the ICs Unlike a Heathkit, SWTP's instruc- are prone to damage by static elec- tions don't spell out every step. You get tricity, the C -MOS types are, and it This is what a 4K memory board looks a rather good pictorial (two color) for takes just a flick of the finger to zap ICs for 2K of memory. like with only the IC We've left the other 2K of memory chips each board, a separate parts list, a set an IC. So don't open any packages out so you can see the extensive use of of general instructions, and you use until told to do so, and don't open or sockets. Contrary to what SWTP says, if all three to determine what part goes handle the ICs until you're properly you don't want heartaches, use sockets for where, and when. The component pack- grounded. If your soldering iron doesn't all ICs. Only the voltage regulator, which aging is unusually good. As a general have a three -wire (grounded) power must be secured to a heat sink, does not rule the components are packaged for cord never apply the iron to the PC have a socket. a small number of steps; when you board(s) once the ICs are installed. complete one package you (generally) Testing. If you're extra careful, and 4K memory. Unfortunately, it doesn't. 4K BASIC actually needs about 4.5K of memory; so a computer must have about 6K of memory in order to program using 4K BASIC. On the other hand, 8K BASIC needs only 6.5K for the interpreter; so 8K of memory handles 8K BASIC very well. Since 4K of memory cannot handle 4K BASIC, most users of personal computers with 4K memory use a smaller version of BASIC known as "Tiny BASIC," which is good for little more than playing games. For the average hobbyist, we don't believe a computer system should be limited primarily to games. We strongly suggest the SWTP 6800 computer system should be obtained with at least 6K of memory. The stripped down SWTP 6800 com- These three boards, which plug into the'mother board, make up the basic computer kit consists of a "black box" puter. The central processing board is on the left, the 4K memory board on the ($395) with just an illuminated power right, and the serial input /control interface is in the center. Additional memory switch, a reset switch, a mother board, and interface boards can be plugged into the mother board.

76 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com double -check every step, the computer a special package price on the SWTP kit should take a couple of long eve- computer with an additional 4K of nings, maybe ten hours. To check out memory and the 8K BASIC. the computer you will need some form We suggest you purchase your com- of terminal. Many of you will not un- puter hardware from a local dealer derstand one word of the rather exten- because he will give you some degree of sive check out and programming in- free or low cost assistance if you have structions, that's where someone who problems. While our problem was only has taken a computer science course a single defective IC in the kit, it might comes in. He can run the diagnostic have been a real hassle to handle it by programs specified in the instruction mail or phone. Further, when we found manual. These diagnostics can pinpoint we had a defective 4K tape our local almost any defect, whether a defective Connections, from the terminals and other dealer swapped the tape on the spot. peripheral equipment, are normally made component or a wiring error If you Would We Do It Again? through grommeted holes in the rear of The answer have purchased the kit from a computer is the cabinet. We have installed a Type -D yes. Looking back at our problem(s), specialty store, such as one of the Com- connector so with proper jumpers in the the actual construction of the kit, and puter Marts, they might check out your associated plugs the single serial /control the final result in respect to the 8K boards in their own system; it depends interface can be used for 110 or 300 baud, BASIC available from SWTP, we would on the particular store and the guy and TTY or RS -232 input /output. start out in personal computing exactly running it. If you make a botch of the the same way, with a SWTP 6800 com- assembly, some computer specialty relation to other computer kits, its built puter kit. The only change we would shops will do the service for you at a in monitor system (Motorola's MIK- make in our system would be to save modest fee. A friend who has studied BUG) and a notably excellent BASIC space by using a CRT TV terminal computer science, or the specialty shop, interpreter. The system's only problem instead of a model 33 TTY, and we are your two best bets if you have is common to all presently available would use an inexpensive optical reader problems. SWTP tries hard but they're personal computers: you lose the pro- to feed the 8K BASIC tape into the just not geared for extensive service. grams when the power is turned off. computer. We would sacrifice the "hard They will supply parts by mail rather Either SWTP or an accessory supplier copy" of the TTY for the compact size quickly, and try to answer your letters. will eventually come out with a non- of a CRT terminal, adding a line printer But, getting them on the phone can be volatile extended BASIC (8K or for hard copy at a later time. But, all in rather expensive at long distance rates. greater) in PROM, ROM, or EPROM; all, we find we are using the SWTP That's why we suggest you latch on to and, there is word that someone is 6800 computer in preference to our a college student before you tackle a working on a FORTRAN compiler for time -share system; in the long run it computer kit, or deal with one of the 6800 system. will work out less expensive than pay- SWTP's major dealers (the price is the Getting Started. As you have sur- ing hourly charges for time -share com- same from SWTP or a dealer). mised by now, you need a lot more puting. The only problem we had with the equipment than "just a computer" in basic computer kit was a defective IC- order to have a computer system. For thank heaven we used sockets! starters; you must have an Automatic When completed, the computer kit Send and Receive Teletype (ASR had 4K of memory, which could do TTY) so you can feed in program very little other than run the diagnostics tapes: if you can't feed in long pro- and a few simple programs and games grams by tape you're back to games. (those games again). So, we purchased Alternately, you might prefer a CRT an optional 4K memory board, giving TV terminal, in which case you will us a total of 8K memory, and we need either an optional, punched tape loaded in a 4K BASIC tape, and found reader, (a reasonably priced accessory), we had no multiplication -the tape was or a cassette recorder and an interface defective. After getting a good 4K tape between the recorder and computer we had a flexible language suitable for (cost slightly greater than a paper tape high school level math, and many elec- reader, and you must build the inter- Our college computer technology student tronic programs. After a long wait, face. Programs are available on cas- was Morris Balamut, who is also the man- because the demand exceeded the sup- sette tape for slightly less than the cost ager of the Computer Mart of New York. ply at the time, we got our 8K BASIC of the same program on punched This is our memory board he's plugging in paper to the store's own SWTP 6800 to check for tape which opened up a whole new tape). proper operation one board at a time). world. The SWTP is a 8K BASIC You need the 6800 base computer, Turned out we had a defective IC. We powerful interpreter allowing such an additional 4K of memory, a termi- strongly urge you do not tackle a corn - things as trancendental functions char- nal, some form of paper or cassette tape puter kit unless you have a college level acter strings, and user defined func- reader, and a BASIC interpreter pro- computer technology student and /or a tions. Fact is, the SWTP BASIC is gram if you plan on anything more local authorized kit dealer to back you up much more powerful than the BASIC in than playing games or writing simple if you have problems. In many instances the time -share system of our local cen- programs. you'll find that store personnel and college level assistance are one and the same. tral high school district, and they have Often, if you make arrangements to a notably good computer If you must get service direct from a system and get all your equipment from one source computer manufacturer you might course. be in in a package deal, some items will be for a long wait. When the price direct or The SWTP 6800 computer is our thrown in at a "discount" or "free." At from an authorized dealer is the same present choice for -a personal computer the time this article was being prepared, (don't forget to allow for shipping charges) because of its relatively low cost in the Computer Mart of New York had get your computer kit from a local dealer.

ELEMENTARY ELECTRONICS /September- October 1977 77 www.americanradiohistory.com by James A. Fred In the last issue of ELEMENTARY using the 112A or 71A. Hello, out there in Radioland! we shouldn't forget the Your cards and letters have been most ELECTRONICS I wrote about substituting Of course which is a 2 VDC filament helpful in telling me what collectors tubes in AC- operated radios. There are type 30 tube want to replace all the want to know about their old radios. many tubes that were made in the 30s triode. If you a and have a 3 -volt battery Keep writing to me because this is the still around so you should have no trou- 201 As in set the filaments you can plug in only way I can help you find greater ble finding the ones you need. However to supply get good results. Just be enjoyment and satisfaction in your col- what to do with radios that use the type 30s and has the right sockets to old radio equipment. WD11, WX12, UV199, UX199, 201A, sure the radio lection of can also replace the Williams, an antique radio etc. is becoming a major problem to accept the 30. You Arthur with a type 30 if from New Zealand, is going to collectors. Some collectors have decided WX12, and UX199 collector filament voltage. tour England, Canada, and the United to wire transistors underneath the tube you use the proper Tougher Tube Substitutions. States during 1977 and 1978. He wants sockets and leave dummy tubes in the Some Now that we have discussed the simple to visit as many radio collectors as his sockets. Now that may be fine for the plug -in replacements let's get to the schedule will allow. If you would like collector who doesn't care about retain- difficult UV199 for the UX199. to visit with him drop me a line in care ing the integrity of an old radio. I am more has a different base pin this magazine and I'll turn your opposed to this practice as is every other The UV199 of from the UX199, which name and address over to him. He will serious minded collector who is trying to arrangement the normal pin size and location. then see if he can fit you into his preserve his old radios for posterity. has The tube pins are small nubs that only schedule. Some Good Tube Substitutions. This about I/s inch from the tube The Indiana Historical Radio Society column will deal with several methods extend and the filament pins are 180 de- a very successful meeting in con- of providing substitute tubes to make base held than side by side. with the Antique Wireless As- some of the older radios (1920 -1924) grees apart rather junction sketch of the tube pins as sociation at the Auburn- Cord- Dusen- operate in their original way. That is to Here's a viewed from the bottom of the tube. berg Museum in Auburn, Indiana the say I won't suggest changing tube sock- the UX199 has two larger - middle of April. Two radio auctions ets or mutilating the radio in any way, Note that diameter filament pins which makes it were held, there was a display of old but will tell you how to alter tube bases difficult to insert it improperly into the radio equipment, a flea market, and an or suggest tubes that can be plugged in socket. Back in the 20s adapters were old radio equipment contest which en- and give results equal to the original you could use a UV199 in the tertained the members. An evening ban- set of tubes. made so socket, or even use it in place quet brought an end to this very enjoy- To begin our discussion an easy con- UX199 of a WX12 or 201A. The 99s required able Antique Radio day. version is to use a type 40 in place of a 200A or a 201A. There are a few dif- only 3.0 to 3.3 volts DC on the filament ferences in the characteristic of the 40 which meant that you could use 2 No. and the 201 A. These aren't serious to 6 dry cells in series for the filament the collector, but I would not recom- supply. In remote areas this was more mend using the 40 in the last audio convenient than using a storage battery stage to drive a speaker. The 40 re- that had to be recharged every few quires 5 VDC at .25 amps, just as the 201A does. The amplification factor of the 40 tube is 30, while the 201 A's is 8. The plate current of the 40 is .2 mA while the 201A draws 3 mA. The 40 will tolerate a higher plate voltage because its plate resistance is higher. Another substitution is the type 112A or 71A in place of the 201 A in the audio output stage of a 5 -tube battery Since the 71A was used in many Beautifully restored and working perfectly, This Radiola 25 came complete with an- radio. there seems this Zenith 3R receiver was a winner in the tenna, and was entered by Lionel Haid, of of the early AC receivers restoration contest at the Indiana Historical Richmond, Indiana. As you can imagine, to be a good supply available. Usually Radio Society meeting, in Auburn, Indiana. this set is as rare as it is good -looking. a C -bias battery is recommended when

ELEMENTARY ELECTRONICS /September- October 1977 78 www.americanradiohistory.com weeks. You can make an adapter by lar glass bulb 1 -9/16 -inch in diameter. mounting a socket which will hold the This diameter may be too large for UV199 on top of a 4 -pin tube base and some of the older radios. The 1H4G wiring the socket lugs to the proper tube has the same characteristics as 30. base pins. Likewise you can make an The next step is to remove the glass adapter for the UX199 tube to be used bulb from the base. The wires soldered in a set intended for 201 As. The photo into the tube pins help hold the base to shows one such adapter. A long screw the bulb plus there is cement holding can be used to hold the socket and the base to the bulb. Over the years base together. much of the cement will have dried out I have saved the most difficult substi- and left the base loose on the glass. Put tution for the last. This is the substitu- on a pair of leather gloves and grasp tion of an 864/VT24, a type 30, or a the bulb in one hand and the base in 1H4G for a WD11. It is nearly impos- your other hand and twist Some sible to find a WD11, which many col- bulbs will come loose this way real find! lectors need for the Radiola III, the A This rare and beautifully restored and others won't. If the bulb Federal Jr. crystal receiver Balanced Amplifier, was seen on dis- Radiola IIIA, and doesn't come loose place the tube in the play at the Indiana Histoical Radio Society the Radiola Grand as well as other (Continued on page 99) meeting in Auburn, Indiana held recently. radio sets. Nearly every collector has one of these Radiolas, but very few TUBE ADAPTATIONS have working tubes in them. The 864/ FOR ANTIQUE RADIOS VT24 is a non -microphonic version of the WD11 developed by the PIN Army Sig- Fil. INDEX 1. Grid nal Corps, 1. except that it has the small, 2. Plate 2. Fil. + regular, 4 -pin base with .186 DIAMETER 3. Plate two large and 3. Fil. - 2/ t two small pins. The large pins are for 4. Grid 4. Fil. - the 1.1 VDC filament which is the same as the WD11 requires. This makes the 3 I O O i 4 INDEX PIN DIAMETER 864/VT24 compatible with the .125 .154 WD11 DIAMETER except for the base pin locations. There UV199 2 O t O 3 have been many methods used to adapt 3 the 864 to the WD11 configuration. 1. Fil. + W D-I I .125 You can remove the base from a de- DIAMETER 2. Plate funct WD11 and by grinding out the 3. Grid base, force an 864 into it. The main 4. Fil. - UX199 1. Grid trouble with this idea is that you have 864/VT24 made the WD11 unfit for use as a non- 2. Fil. - working display tube. A better way is 3. Fil. + 4. Plate to leave the WD11 as is and use it for display only. Some collectors have no desire for their sets to play, but only Here shown are the differences in pin size and placement for the four old -time tubes want them to look like new. discussed in the text. The pins are viewed here looking from the bottom of the base. Preferred Method. The method I pre- Note carefully the differences fer is to remove the glass bulb from the as to which pin is connected One of the main problems to be base (either the 864/VT24, type 30, or to Fil.-1 -, Plate, Grid and to faced when adapting old -time the newer 1H4G), remove the two Fil. -. It's hard to go wrong tube sockets is figuring out larger pins from the base, make a new if you follow these diagrams. just what each of the pins is large pin (plate) and stake it in the Your antique radio will soon connected to. There has never proper position along with a new small be as good as new -and even been any sort of standardization. pin for the other filament lead. Now work in the same way! In fact, even the diameters this isn't of the pins aren't constant. at all difficult if you have GRID patience, and are reasonably handy with tools, and have a source for the pins needed. The first thing you must do is to PLATE obtain a supply of 864s, 30s, or 1H4Gs. Check with your friends, old radio repair shops, war surplus electronic part stores, or look in a copy of BUDGET FIL REGULAR 4 PIN ELECTRONICS for a list of suppliers of TUBE BASE old vacuum tubes. The type 30 was made in two bulb shapes. One is tubular FIL. about the same diameter as a small 4- SOCKET TO HOLD A UV 199 TUBE pin base, the other has the small dome Here's an arrangement that allows you to shaped bulb. The 864/VT24 has a test old- style, four pin tubes in modern It's easy to make an adapter to use a tubular bulb 1 -3/16 -inch in diameter four pin sockets such as those on most of UV199 tube in place of the older UX199. which is nearly the same as the WD11. today's tube testers. (See text for details). The 1 H4G is an octal tube with a tubu-

ELEMENTARY ELECTRONICS /September -October 1977 79 www.americanradiohistory.com WithAnPower O GENERATOR"

Your energy troubles may be gone with the wind!

D Tilting at a windmill in Boroughbridge, the wiíid. up with an idea to link the blades to- England might prove a shocking experi- Sir Henry Lawson Tancred, an engi- gether like the spokes of a wheel. This ence to a latter -day Don Quixote. This neer, aviator and owner- designer of the did damp out the oscillations. He then windmill, situated on the country estate Boroughbridge windmill takes pride in used fixed -blades rather than ones with of a North Yorkshireman, is more than pointing out that his is the largest, private variable pitch in an effort to keep costs a scenic eyecatcher -30 Kw. more. venture into windpower since the 1950's. down. He solved the resultant problem The traditional, centuries -old tech- Sir Henry, both nobleman and techno- of variable rotational speed with a system nology of harnessing the wind has been crat, refers to his creation as an "aero- of hydraulic pumps that ensure a steady reworked and modernized with a view generator," to distinguish her from her pressure runs the generators. towards solving one of mankind's more plebian sisters who do nothing but According to the aerogenerationists, newest, and urgent, problems. Where is grind flour and look good amongst the windmills are the coming thing. Even the power to run civilization going to tulips. now, Sir Henry envisions a "100 meter in come from in the next decades? Fossil The aerogenerator can produce up to diameter wind -wheel rated at about two fuels are being depleted, nuclear tech- 30 Kw. of useable, electric power. Sir megawatts and costing a mere fraction nology seems caught in an environmental Henry's prototype presently drives a 5 of the US designs." bind, solar energy is not yet reliable on a Kw. generator that, even at low wind Windmills may be a part of the solu- large scale -perhaps we should look to speeds, can produce grid -synchronous tion to the energy crisis and, one thing power which can be fed to the grid net- for certain, Sir Henry's ideas aren't go- work and from there into homes. When ing to blow away! the wind rises, the aerogenerator can produce on a second generator another 25 Kw. of non -synchronous power to be used for many heating purposes. The windmill (pardon us, Sir Henry), could easily produce all 30 Kw. as grid - synchronous but, as Sir Henry said, that "would have been too much for the little single -phase grid line" which runs through Sir Henry's estate of Ald- borough Manor. Though the windmill uses standard components, which helps to keep its cost at a reasonable level, the technological problems involved in its design were nothing to be sneezed at. Americans at the Lewis Research Center in Sandusky, Ohio found that out when they tried to build a power -generating windmill. Their The aerogenerator uses standard compon- version cost much more than Sir Henry's On the pole to the upper left of the wind - ents such as fixed blades instead of variable - aerogenerator and, due to blade whip- mill you can see the special installation pitch ones. Even though it rotates, due to lash and tower oscillations, it never oper- which receives the grid- synchronous por- the fixed blades, at a constantly varying ated above 50 per cent efficiency. tion of the generated power. Once into the be directed to speed, a complex hydraulic system ensures Sir Henry drew on both his engineer- main power- network it can wherever it may be. needed. the generators turn steadily. ing and aviation backgrounds and came

80 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com Your FM is good for a lot more than local music - even portables can pull II-FI DX in distant stations if you play them right.

You say you have a problem? Feeling are propagated, or reach the receiver Both of these methods, however, involve low over Radio Moscow? The standard from the transmitter. Meteors provide techniques and methods of interest to AM band getting pretty bland? Ah yes, one way, as the ionized trails left by advanced DXers. Fortunately, most FM you have a case of the "DX blahs," which meteors entering the Earth's atmosphere DX is the result of propagation modes is the result of getting into a rut with your can actually reflect FM signals over that are easier to use. SWL activities. The only cure, my friend, great distances. Auroral reflection is an- Sporadic -E is by far the most spec- is to try the "higher Hertz " -88 to 108 other method, and is associated with the tacular method of FM DX reception MHz to be specific, the home of FM Northern Lights. FM signals are actu- that the beginner will encounter. Spor- broadcasting and FM DXing! ally reflected off the auroral curtain. adic-E takes place in the E layer of the FM DXing is now the "in thing" Earth's atmosphere approximately 50 among DXers in the know. You can't miles above sea level. For reasons not tune the world anytime you want, like yet completely understood, scattered on shortwave, nor can you easily tune patches of intense ionization form in in distant stations like on the AM the E layer of sufficient intensity to re- broadcast band -but where else can you flect FM signals over long distances. A DX in stereo or quadraphonic sound? typical range for sporadic -E skip is be- And FM DXing is trailblazing -we are tween 40 to 1200 miles. Sometimes the still unraveling the mysteries of long - FM signals will reflect off more than distance reception at FM frequencies. one cloud, resulting in reception at dis- Finally, you can DX without a kilo - tances of 2500 miles! Sporadic -E skip is dollar receiver or monster antenna sys- also one of the kindest DX methods for tem. If you have an ordinary portable the FM newcomer, for it is often just as or table radio that covers the FM band good (and sometimes even better) on you have all you need to start FM DX- portables and table radios as it is on ing today. expensive receivers and fancy antenna As one example, on a July afternoon systems. When sporadic -E is taking in 1975 your author heard FM stations place, stations over 1000 miles away from New Hampshire to North Dakota blast through at local levels, even over- on a simple $30 AM -FM portable using powering semi -local stations! only its built -in whip antenna. Such an A more subtle method of propaga- experience is actually common in FM The simplest type of FM antenna, the old tion is tropospheric bending. Tropo, as "rabbit ears." DXing. The secret lies not in your It can get some amount of it is called, takes place when two differ- equipment or in an extensive knowledge directivity by the easy technique of just rotating ing air masses meet. A typical. case is of radio. Rather, FM DXing depends the two elements by hand. When conditions are right, it will give surpris- where cool Pacific air from the West upon being in the right place at the ingly good results. lust remember, if you encounters warm, moist air from the right time! want this type of antenna, don't go for Gulf of Mexico. At the boundry point Propagation Possibilities. There are elaborate knobs and slides. They don't do where the two air masses meet, a "duct" four main ways in which FM signals anything at all to help reception. is formed that traps FM signals and

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Ranges for sea level to about virtually all of its sen- as as tropo DX are not ordinarily long sitivity is concentrated for sporadic -E, usually only a few hun- along the axis. dred miles, but tropo charting has produced reception of FM stations from Houston in New York. When to DX. Sporadic -E is highly un- predictable, and may take place any time of year. However, peak activity is black bars across the TV picture, cool dawn air and causes atmospheric garbled audio, ghost pictures on local inversions. Such conditions last until TV stations, and the appearance of TV approximately 9:00-10:00 a.m. local signals on channels normally empty. time and enable listeners to log stations When sporadic -E becomes noticeable on within a two hundred mile radius or channels 5 and 6, it is a sign that spor- less. adic-E is about to reach the FM band. Long -haul tropo of several hundred Generally, sporadic-E does not cover miles is most common in autumn. A the entire FM band. It reaches a cer- check of your newspaper's weather tain frequency, called the maximum maps can provide important tips as to usable frequency (MUF), the highest when tropo might be present. A key frequency on which sporadic -E can produce long distance reception. Sporadic - E skip is generally first noticed in the 88 -92 MHz educational portion of the band. This is where to start DXing if sporadic -E is present. Many DXers work their way up the band, logging new stations as they go, and follow the The servo -rotor unit for an outdoor anten- sporadic -E until it reaches the MUF. na rotator. This control, mounted indoors, Changes of direction are frequent in determines the direction to which the ro- sporadic -E, with DX signals first com- tator will point the antenna. ing from the north and then abruptly from early May to early August, with a swinging toward the west, for example. lesser period of activity from late De- This is due to the fact that the spor- to early January. Daylight hours adic-E clouds themselves are in motion. cember gear assembly for an out- with mornings and early eve- Your author has heard sporadic -E skip The motor and are best, door antenna rotator. The unit must be site usually best. all way from New England to nings at your DX swing the sturdy enough to withstand strong winds, it However, most top FM DXers make the Plains states in a single opening. and to be able to swing the long beam a point to check the band every chance Also, signals via sporadic -E skip are of the FM antenna around. It also must they get during the busy summer FM often loud but quite variable in strength. not be affected by weather extremes. DX season. Rapid fades and audio distortion are high Sporadic -E starts on lower frequen- common. It is highly erratic but superb clue is a slow moving pressure Duct- cies and works its way up the frequency fun while it lasts! system followed by a cold front. into the FM band. Smart FM Tropo is less spectacular but more ing which permits long- distance FM spectrum front DXers keep a check on television chan- predictable than sporadic -E. Tropo is reception will exist where the cold meet, and the nels 2 through 6 for signs of sporadic -E virtually a daily happening during peri- and high pressure area the activity on television. Sporadic -E on the ods of fair weather because of sunrise duct will run the entire length of two air TV channels can be identified by rolling tropo. When the sun rises, it heats the boundry line between the masses. Tropo is also common in coastal areas. Listeners along both the Atlantic and Pacific coasts will note enhanced reception of stations up and down both coasts during summer evenings. Tropo openings are also frequent between the coastal areas of the Gulf of Mexico. Tropo is fairly common in the eastern two -thirds of the United States, but is rare in the more arid and mountain- Two different types of omnidirectional antennas. Each one provides a pattern of sensi- the West. Tropo is excel- is as nearly circular as possible. With these units an antenna rotator is ous areas of tivity that the Pacific unnecessary since nothing is gained by turning them, although the lack of a reception lent, however, up and down pattern concentrated in one direction means that a lot of sensitvity is lost. coastline west of the mountains. (Continued on page 102) October 1977 86 ELEMENTARY ELECTRONICS /September- www.americanradiohistory.com SVA SCASOOTHER

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There are more possibilities for music than you thought in your FM tuner. e/e shows you how to make them real. by Herb Friedman OU CAN LISTEN TO SCA BROADCASTS longer will your SCA listening be re- permits reception of SCA programs at far greater distances with this stricted to local FM stations. You can that other low cost SCA adaptors can't SCA (Subsidiary Communica- now monitor fringe reception FM sta- detect. tions Authorization) adapter for your tions with SCA programming. What You Can Hear. For many years FM receiver or tuner than with pre- But before going further let's take a SCA has been used to transmit educa- vious designs, even those costing many look at what SCA is all about. When a tional programs and weather reports to times more. The secret lies in a new in- Subsidiary Communications Authoriza- specialized audiences; it has been used tegrated circuit now available at very tion is granted to an FM station by the for reading to the blind, and even for low prices which decodes the ultrasonic FCC the station is permitted to trans- broadcasting some school tests. The frequency the SCA signal is on. This mit up to three more programs in ad- most common use of SCA, however, is IC is a PLL (Phase -Locked Loop) dition to its regular program (called the transmission of background music which acts as the detector of the 67 the main channel program) by a spe- -the type heard in restaurants and kHz SCA carrier wave which the sub- cial method of modulation. A standard shopping centers -and ethnic music. sidiary signals are transmitted on. FM radio -either mono or stereo -can- For example, in the New York City Although most people are unaware not detect the SCA programs. The reg- area there are FM stations with SCA of it, many FM stations transmit not ular listening audience hears only the programs of the music of China, just the two signals of a stereo pro- main channel programming. In fact, Greece, Ireland, and many others. gram, but one, two, or even three other there is no way a listener with a stand- Best of all, this pleasant, interesting programs, usually music, which cannot ard FM radio can tell the station is music is rarely, if ever, interrupted by be heard by the owners of normal FM transmitting an SCA program(s). Only an endless barrage of commercials or tuners or receivers. These programs can listeners with FM radios equipped with the patter of an announcer in love with be heard only if you have a special an SCA adaptor can hear the SCA pro- his or her own voice. SCA receiver, or if you have an SCA gram. How It Works. SCA programming adapter, similar to the one described in If you would like to tune in to these is transmitted by a 67 kHz FM sub - this article. "phantom broadcasts" you can do so carrier (or sometimes 65 kHz impress- Our SCA Super -Soother is so- called with Super- Soother SCA Adapter. It's ed on the main FM carrier). When a because the most common use for SCA super because its extra -high sensitivity station broadcasting SCA is received is to transmit Muzak -like background music into stores and factories. It uses C5 C2 R2 CI two ICs which cost $6.00 (total, in- RII C13 C12 RIO CIO R9 C7 C6 C4 cluding postage) plus a handful of resistors and capacitors. Because of the advanced design made possible by the PLL IC, Super- Soother can grab SCA Here's the way the completed signals which ordinary SCA adapters board looks. You can make would lose completely, or at best re- your own circuit board, or order it. Perf ceive with lots of hash and distor- board construc- /or tion won't do in this project. tion -and who needs that with soothing background music, music to lull you by . . . or whatever? Using a two IC circuit in an amplifier / (PLL)-detector configuration R3 C3 RI Super- Soother will actually permit you CI7 RS CII R7 R5 R6 R4 to DX your FM -SCA programs. No

ELEMENTARY ELECTRONICS! September-October 1977 87 www.americanradiohistory.com @/@ SUPER SOOTHER by a standard FM radio or tuner the OUT SCA subcarrier is simply wiped out in the radio's detector and the listener has no idea it exists. To receive SCA the regular FM detector output must be fed into a 67 kHz detector before the 67 kHz subcarrier is eliminated by the standard FM detector's deemphasis network. Until recently it took a lot of expensive hardware to receive SCA programs: a very sensitive receiver and a rock -steady detector. (A good receiver is needed because the SCA subcarrier Exact -size printed circuit board layout is shown here. Transfer the image to copper clad is usually only 10% of the total FM board using carbon paper. This is the bottom (copper) side. signal.) Though many low -cost SCA adaptors have been available in proj- unusually high it must be assembled filter C9 and R5 to IC2, the PLL detec- ects, or in wired form, most had a sen- on the circuit board exactly as de- tor. IC2's output is passed through a dency to burp, gargle or distort on scribed to insure stability. You can't low -pass filter consisting of C12, C13, weak SCA levels. build this project on perfboard. C14, R9, R10 and R11 which provides While the radio astronomy crowd How The Circuit Works. The signal SCA deemphasis and noise suppres- had a great weak -signal detector known from your FM tuner's detector, before sion. The output level at C15 is about as the phase- locked loop or PLL, it deemphasis, is applied to operational 50 to 100 mV depending on the par- was also true that the astronomical -use amplifier ICI through a high -pass filter ticular signal, and can then be fed to PLL was astronomical in price. Thanks consisting of C2, R1 and R2. The fil- your hi -fi amplifier. to modern solid -state techniques, how- ter's effective frequency is 60 kHz, Since SCA audio response is limited ever, the Signetics Corp. has come up which removes just about all of the to a maximum of 7 kHz just about any with a PLL specifically intended for main - channel information. The fre- amplifier can be used. SCA detection that's priced well under quency response of the amplifier is Note that Super- Soother requires a $5. tailored by the feedback loop through bipolar power supply in the range of Available in both the standard 8 -pin R3 and C3 to further suppress main - ±6 to ±9 VDC. The supply can be round ar1. the 14 -pin DIP IC packages channel information. either batteries or a power-line bridge the Signetict SE /NE565 requires virtu- ICI's output is fed through high -pass rectifier using a center -tapped 12 -volt ally no external hardware for SCA detection. Most important, since the PLI_ automatically locks onto the incoming SCA subcarrier frequency the SE/ IIMMIA1111111111 NE565 will demodulate subcarriers of 111111111111/1111111111 either 67 or 65 kHz without need for "911P.Iir"r","41/1 individual adjustment. Combination Gets Results. Unfortu- r%`rArl/1rr< .Ii1r.ri nately, the phase -locked SCA detector requires at least 80 mV input from the FM detector for good reception, and .111/1111." this usually means that only one or two very strong, or local SCA stations can be received. To make our Super- Sooth- er the best there is we have combined the PLL with a high gain operational amplifier. The result is the Super- Sooth- er which can receive SCA programs even using a cheapie FM radio and an indoor (rabbit -ears) antenna. Another plus feature of Super- Sóoth- er is that no large filter coils are needed to suppress the main channel program. Even SCA programs on stereo stations are received cleanly, with no trace of stereo hash. And because large coils aren't need the entire adaptor can Oscilloscope patterns will pinpoint any possible difficulty. You can use a general purpose to be assembled on a 21/4-in. x 41/4-in. scope since the signals are under 100 kHz. With "triggered" scopes, set the time base u sec /cm. is as in A, printed circuit board which you can Photos B and C are input and output of IC1, the 67 kHz amplifier. If signal clipped purchase, or make, as you wish. main channel program may break through-see text for curves. Normal IC2 pin 9 waveform is Because the gain of the adaptor is shown in the waveform of D. Vertical sensitivity B, 20mmV /cm; C, IV /cm.

88 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com filament transformer as shown on the photo C, the trouble is in the IC1 circuit. lar battery power source or an AC schematic. Since the SCA adaptor re- If you get photo C but not photo D, the supply can be used. Since there is no quires only about 10 mA of current any trouble is in IC2. difference (in this case) in perform- small power transformer can be used. If you don't get photos C and D, there ance between a ±6 and ±9 VDC sup- Assembly. If you cannot make your is most likely a major fault in the assem- ply use whatever you have available. own circuit board, you can purchase a bly; we have specifically designed the For long -term battery life Burgess Z4 drilled and plated board. See the parts adaptor so one defective IC cannot dis- 6 -volt batteries are suggested. However list for information. able another IC. regular (or long -life) 9 -V transistor bat- If you make your own board use a Setup And Checkout. Either a bipo- teries will work fine. #56 bit to drill the holes for the push - in connecting terminals and trimmer PARTS LIST FOR SUPER -SOOTHER potentiometer R8. Drill the corner mounting holes to clear a #4 screw. C1,9- 470-pF capacitor (Radio Shack 272 -125 S1 -SPST switch (Radio Shack 275 -602 or Drill the component holes with a #58, or equiv.) equiv. C2 -47 or 50-pf capacitor (Radio Shack 272- #59, or #60 bit. Misc. -- Cabinet 6 -in. x 4 -in. x 2% -in. or 121 or equiv.) Install IC1 and IC2 before any other larger (Radio Shack 270 -252), two bat- C3- .005 -uF capacitor (Radio Shack 272 -130 components. Note that the ICl lead teries 9 -VDC or 6 -VDC unless power sup- or equiv.) ply is used, battery connecting clips, opposite the case tab is Insert the #8. C4,7- -.1 -uF capacitor (Radio Shack 272 -135 phone jacks, wire. solder, etc. leads- beginning with #8 and push IC1 or equiv.) within IA to 3/8 -inch of the board. C5,6-100-uF, 16 -VDC or better electrolytic An etched, drilled, printed circuit board for Solder the leads and cut off the excess. capacitor (Radio Shack 272 -1005 or equiv.) the Super- Soother SCA Adapter is available If this is your first IC project it C8 -.7 or 10 -pF capacitor (or use two Radio front Electronic Hobby Shop. Box I92, Brook- would be wise to use IC sockets. Shack 272 -120 capacitors wired in parallel) lyn, NY 11235 for $6.95. US orders add $1.50 Hold the board so you are looking at 010,11-- .001-uF capacitor (Radio Shack 272 - for postage and handling: Canadian orders add I26 the top, with IC1 to your left. Hold IC2 or equiv.) $3.00. No foreign orders, please. Postal C12,14-.02-uF capacitor (use two Radio money orders will speed delivery: otherwise so the notch is away from you and Shack 272 -1065 in parallel) allow 6 -3 weeks for delivery. NY state resi- insert IC2's leads into the matching C13,17-- .05 -uF capacitor (Radio Shack 272- dents must add sales tax. holes. Doublecheck the notch ' before 134 or equiv.) soldering. IC1 -op amp integrated circuit Signetics The two 1Cs for this project are avail- Install trimmer potentiometer R8 NE 531T (available from supplier listed able from Circuit Specialists Co., Box 3047. and solder. Then install the three wire below) Scottsdale, Ariz. 85257 for $6.00 which in- jumpers, and finally, the remaining 1C2- phase- locked -loop SCA detector inte- c'udes shipping and postage. grated circuit Signetics NE 565A (avail- components, taking extreme care the PARTS LIST FOR POWER SUPPLY able froin supplier listed below) polarity of capacitors C5 and C6 is -SOOTHER R1,5,6- 4700 -ohm, 1/2-watt resistor FOR SUPER correct. Note that C5 has the positive (Radio Shack 271 -000 or equiv.) C15, 16 --2000 or 2200 -uF. 20 VDC or better lead connected to ground. R2,4- 47,000 -ohm, 1/2 -watt resistor (Radio electrolytic capacitors (Radio Shack 272- While capacitors C12 and C14 are Shack 271 -000 or equiv.) 1020 or equiv.) indicated as 0.02 uF they aren't the R3- 470-ohm, 1/2-watt resistor (Radio Shack SR1 -4 -- Bridge rectifier or separate diode easiest to obtain in miniature size. You 271 -000 or equiv.) rectifiers -- anything orer about 15 mA will can substitute two parallel -wired 0.01 R7-1.300-ohm, ?í -watt resistor (Radio Shack do (Radio Shack 276.1151 is an inexpen- uF capacitors. 271 -000 or equiv.) sive bridge rectifie- rated more than R8 -5300 enough.) The three oscillosope traces show -ohm potentiometer, circuit -board mounting (Radio Shack 271 -217 or equiv.) T1- -Small 12.6 -VAC filament transformer what you can expect to get if you are R9,10,11 -1000 -ohm, !%s -watt resistor (Radio (Radio Shack 273 -1315 is more than ade- tuned to an SCA station. Photo B is the Shack 271 -000 or equiv.) quate.) input, IC1 pin 2; note the presence of a 67 kHz carrier. Photo C is IC1 pin 6; +6 TC Sic +9 VOLTS note the very strong ' 67 kHz carrier. Photo D is IC2 pin 9, the phase lock de- Y6 VOLT Bi C7 R7 BATTERY tector's voltage controlled oscillator tri- 100µF IµF 1.8K CIO SUPPLY Ce .001µF angular wave output. 10pF Siby, C2 If you don't get B, Cl -7 --1 I -V photo the trouble IOOK 470pF 47pF e Re c9 10 470pF 5K 132 is the connection between the tuner and --1 I SEE tEXTI ICI 6 2 _ F7. the adaptor. ,NPut 11 14 If you get photo B but not RI R2 2 NE531T,,4 IC 2 3 NE565A R9 RII C17 4.7K 47K IK I 1K .05µF FM DETECTOR I I R4 VV, TRANSFORMER 9C" 1 ^/------, R5 R10 41K C4 47K >47K 1- IK IµF 001 a2 Ci3 C14 NE565A R3 _µF .02µ, T 05µF 4701I --i F--- 14 8 T.02µF í) MPX 0 1 .l C31 ( OUTPUT I 4- CHANNEL 005 -I- C5 TrT T OUTPUT PF 100p IN SOME I 7 TOP VIEW OPTIONAL AC RECEIVERS -610 POWER SUPPLY TO STEREO -9 VOLTS Tr DETECTOR SR2 I--<+9VOLTS CONNECT MONO NE531T SRI +CIS SCA SUPER - SOOTHER IC OUTPUT 117 VAC HERE ° + 016 1 8 zSR4 The Super- Soother (or any other SCA adap- BOTTOM VIEW < 9 VOLTS tor) is connected after the FM detector, but before the deemphasis network, as here

ELEMENTARY ELECTRONICS /September -October 1977 89 www.americanradiohistory.com have the correct connection as they are adjusted. Note that some stereo sta- from before tions can cause sound bursts that ap- SUPER SOOTHER all FM detector outputs 10 the deemphasis network. pear to be SCA. If adjusting R8 doesn't Connect the tuner's detector output clean up the bursts it's not SCA. Note Super- Soother connects to your ra- to the Super- Soother with the shortest that once R8 is properly adjusted there dio or tuner between its FM detector possible length of shielded cable, or is no stereo hash interference with SCA and deemphasis filter. If you connect install it directly inside the tuner or signals; hash will only be heard from after the deemphasis filter you will receiver if there is sufficient room. Con- non -SCA signals. find the 67 kHz subcarrier has been nect Super -Soother's output to any Problems? The high sensitivity of filtered from, the detector's output sig- high -gain amplifier such as the micro- this system may require that the over- nal and you will get nothing but noise phone input of a hi -fi or general -pur- all gain be reduced. In the event you from the Super-Soother. The drawing pose amplifier. cannot receive any SCA stations you shows a typical FM detector output, the Locking The Loop. Tune in a station either have none in your area or you deemphasis network, and the correct you know (or believe) is transmitting have made a construction error. Here connecting point for the adaptor. Since an SCA program (a call to the station are some hints to help. it is possible the Super- Soother will should get you the info) and adjust 1) If your problem is a weak signal load down the detector for normal FM trimmer potentiometer R8 for best SCA resulting in high frequency noise try reception I suggest a switch be installed sound quality. Normally, the reception changing C12 and C14 to 0.05 uF. so it can be removed from the circuit will be almost completely garbled and 2) If your problem is background when not being used for SCA listening. then fade into a clean signal as R8 is breaking through from the main chan- Super- Soother is most conveniently adjusted. As R8 is adjusted further the nel the problem is probably caused by connected through a phono jack install- sound will again garble. Set R8 so it adaptor overload (clipping). Simply ed on the rear apron of the tuner or is approximately midway between the change Cl and C9 to approximately radio, though you can use a direct wire two settings that produced garbled 300 pF. This will attenuate the sub - connection. sound. Usually, the adjustment is quite carrier and clean up the breakthrough If you have one of the older FM broad so don't be too fussy. on very strong signals, though very tuners with an MPX output you al- If you don't know which stations are weak signal might get lost (you can't ready have the correct connection be- transmitting SCA set R8 to its mid - grab, or hear, them all). A second, cause the MPX output is the non - position and tune the station very care- simple corrective procedure is to in- deemphasized detector output. Similar- fully and very, very slowly. When you stall a 100k ohm resistor in series with ly, if you have a modern FM tuner hear anything that sounds like distorted the input from the radio or tuner's de- with an FM detector, 4- channel, or music try adjusting R8 -if its real SCA tector. This effectively cuts down the FM Quadrasound output jack you also it will turn into clean sound as R8 is input signal and eliminates overload-8 Since long before 2001 -A Space Odyssey's Hal, the smarter -than -human computer was born, bridge players have NOT ACCORDING TO HOYLE dreamed of a machine they could play on which would do their remembering A tricky computer can stop you from trumping a partner's ace. for them. And now it's here, called Bridgemaster and it works using a light pen to play the cards. The four -hand electronic game board uses light-emitting diodes (LEDs) and light- sensing pens instead of cards. It allows the players, at the touch of the diode with the pen, to deal hands in split seconds-electronically selected at random by the board -store or recall from the memory bank every card, trick and play of the game. Bidding is simplified with the aid of the memory. In front of each player is a display board consisting of the four card suits, Spades, Hearts, Diamonds and Clubs, with each card shown from One through the Ace. Along with each card sign is a diode which lights up when that card is used. The central area of the display board contains the panel which shows the state of play and the reset diodes. Each player holds his light -sensitive pen to the chosen diode in order to activate his play. Playing the conventional way, with an open partner's hand Each opponent has his own display before him. The light- emitting- diodes (LEDs) show is It's a matter of turning each card in the player's own hand; then, with a touch of the light- sensitive pen to the easy, too. just recall diode the LEDs change to show the cards already played during the game. This the display board around 180 degrees feature frees the player's minds from having to recall cards. after the bidding.

90 ELEMENTARY ELECTRONICS /September -October 1977 www.americanradiohistory.com "Bad SCR" LEDIT Said It Here's a device to check those cheap, surplus bargains.

by David R. Corbin

Everyone loves a bargain, and bar- current and minimum holding -current around today. The correct connection, gain bags of semiconductors often yield are naturally provided by the ohmmeter. when identified, provides for short tests great buys in the form of perfectly All but the cathode -to -gate path may between gate and cathode, cathode and good, but unmarked and untested di- check "open," making it impossible to anode, and anode to gate. It also pro- odes, transistors, and silicon -controlled identify the leads on an unmarked SCR. vides for open tests between cathode rectifiers (SCRs). The trouble is, how What LEDIT does is to provide a and anode, and cathode to gate, and do you go about identifying the leads quick and low -cost way of putting a turn -on /turn -off functions. and testing these semiconductors? safe current through the SCR gate and Here's How It Works. Light emitting A simple, one -evening project using anode circuits, while providing enough diodes D2 and D3 have a current rating light-emitting diodes (LED) both as current to turn on and latch virtually of about 10 milliamps, with between indicators and as functional circuit all small SCRs found in grab -bag assort- 1.5 and 1.8 volts across them. This is parts in the testing process can now ments. normally enough current to turn on be built for less than five dollars. This By placing an ' adjustable resistance any common SCR connected to termi- LED -indicating tester (LEDIT) will and a current meter in series with the nals J2, J3 and J4, and to keep the SCR check out diodes and SCRs, and to anode and gate, you could obtain the conducting after the gate voltage is some will even identify leads of and specified current levels, but for most removed. With the SCR turned on, cur- test many transistors . for opens and quick testing of SCRs (open, shorted, rent will flow through D3 in the anode shorts. or perhaps not even an SCR after all) circuit until the current is interrupted. While transistors are actually quite LEDIT will provide all the information Then the SCR will turn off again, and easy to check on a standard ohmmeter, needed. power can be reapplied to the circuit using the lower voltage, middle -range Checking SCRs. There are five ways without illuminating D2 or D3. scales to prevent excessive voltage or to misconnect an SCR to the three As the schematic shows, voltage is current through the transistor, an SCR posts, and one correct way. None of supplied through J1, or from a 9 -volt is a bit more difficult. As shown in the the incorrect ways will damage a good battery if you prefer. A 9 -volt DC drawing, an SCR contains the equiva- SCR among the vast majority of those transistor radio or tape player AC sup- lent of two transistors connected in a closed feedback loop. One lead is the anode, the other the cathode. A third ANODE ( +) ANODE (+) lead is called the gate. How SCRs Work. Whenever the gate is brought close enough to the voltage on the anode to cause a specified minimum current to flow in through the Ihm cathode and out of the gate, the SCR G ATE GATE ( +TURNS ON ANODE - will suddenly turn On and exhibit a (+ TURNS ON CATHODE) ANODE- CATHODE) "short," similar to the action of a conducting diode, provided current is per- CATHODE (-) v, mitted to flow in the cathode -to-anode circuit. It will stay in this Silicon -controlled rectifier (SCR) is really a mode even CATHODE (-) if the positive voltage is removed from diode which conducts only when a third the gate. Only by reducing the anode element, the gate, lets it. Circuit between anode ( and cathode ( is normally current below a specified minimum ) -) Equivalent circuit of an SCR looks like this - open, until the voltage on the gate ap- two NPN transistors connected. Gate is level can the SCR be turned Off again. proaches the anode. When that happens same as base of lower. It can turn On the The problem with trying to check electrons flow from cathode to anode al- lower transistor, which turns On the base of most common, small -size SCRs with an most as though the diode were a "short." the upper. ohmmeter is that the minimum gate

ELEMENTARY ELECTRONICS /September -October 1977 91 www.americanradiohistory.com then the SCR either cannot remain on Di anode current (which is with a 10 mA CATHODE i LEDIT not too likely, but possible) or it is defective. ly is a very convenient way to power Pushing normally -closed switch S2 small projects like LEDIT which have interrupts the anode current. The, clear low current requirements. More light will go out. When that switch is D2 very JI GATE importantly, if LEDIT is used only released, the light should not come on If it does, there is likely a prob- D3 occasionally a battery may tend to run again. 9 R3 lem with the SCR, or possibly R1 is not VDC 220 down, leak, and become a nuisance ANODE when left on the shelf too long. One small enough for that particular device. si 9 -volt DC supply can power any num- This is not very likely since 1000 ohms ber of projects simply by plugging it in, is getting near the minimum value S2 if you use an external supply jack as used with most SCRs. R2 330 shown here. If Si is pressed and D2 (red) does A negative 9 volt potential is applied not light, then the gate is open. Actu- through diode DI to the rest of the ally, D2 will light very weakly through circuit as a precaution against applying the 1000 -ohm shunting resistor even PARTS LIST FOR LEDIT SCR TESTER reverse power. Resistor R1 is a 1000 - without an SCR in the tester, but it is D1- 1000 -Ply, 2.5 -A rectifier, HEP R0170 ohm cathode -to -gate resistor which easy to tell the difference between a Radio Shack 276 -1114 or equiv.) shunts the flow of current rushing into good light -up and this weak glow. D2 -Red LED (Radio Shack 276 -041 or equiv.) the internal capacitance of the anode - Put It Together. None of LEDIT D3 -Clear LED (Radio Shack 276 -047 or to -gate junction whenever voltage is part values are critical, and any con- equiv.) R1- 1000 -ohm, 1/2-watt resistor (Radio Shack an SCR under test. If it venient "next- size" part can be used first put across 271 -000 or equiv.) the SCR would turn with reasonable results. Resistors R2 were not for R1, R2- 330 -ohm, 1/2 -watt resistor (Radio Shack on every time it was connected, even and R3 are necessary to limit the cur- 271 -000 or equiv.) without a gate signal voltage, an effect rent to D2 and D3 (LED indicators), R3- 220-ohm, 1/ -watt resistor (Radio Shack called dv /dt and meaning "change in and shouldn't be much smaller than 271 -000 or equiv.) voltage with a change in time." The indicated in value. If anything, use St -SPST normally -open pushbutton switch rapidly- applied anode voltage causes a slightly larger values. The gate turn -on (Radio Shack 275.1547 or equiv.) small current to flow which charges the current is rather stiff for small devices S2 -SPST normally-closed pushbutton switch junction capacitance, and it flows so don't hold them "on" with the turn - (Radio Shack 275-1548 or equiv.) Misc.- Cabinet 4 -in. x 21/2-in. x 21/2 -in., -to -gate circuit un- on button any longer than necessary. through the cathode Shack 270 -231 or equiv.), -to- I've tested innumerable smal devices approx. (Radio less shunted by R1. Since cathode jack for battery connection (any convenient were damaged by LEDIT but gate current is what normally turns on and none type), 5 -way binding posts (Radio Shack an SCR, there is nothing very mysteri- when dealing with unknown parts, it's 274 -661 or equiv.), wire, solder, etc. ous about this dv /dt effect. (Continued on page 100) More on LEDIT's Action. Two pushbutton switches control the gate and anode currents of the SCR under test. Switch S1 is in series with R2 and D2 CATHODE and is normally open. This is the gate DI POST RI D2 SI R2 signal voltage. Since "ground" is positive in this design, pressing 51 lets cathode -to -gate voltage flow through D2 and R2. R2 limits the current to a safe value for both the SCR and D2. If the gate is either normal or shorted, D2 will emit red light. But only if the gate is normal will D3, the anode current indicator, come on with a clear light. Letting up on Si should let D2 go out and leave D3 on. If it does not, Author's LEDIT is finished and ready to test unknown SCRs as well as units which have their leads identified. The LEDIT is an easy JI project for a ( FOR weekend BATTERY) builder. Find out the truth Here we have a view of LEDIT's interior, specifically the reverse side of the about those front panel. No PC board is necessary or recommended, just follow the SCRs and author's design of direct point -to -point wiring for neat and easy assembly. diodes!

ELECTRONICS October 1977 92 ELEMENTARY /September- www.americanradiohistory.com BASIC C 011ES IN ELECTIICITY &ELECTRONICS 0/0 RECOMMENDED THEORY FOR ALL CB OPERATORS

This series is based on BASIC ELECTRICITY /ELECTRONICS, Vol. 4, published by HOWARD W. SAMS & CO., INC.

WHAT YOU WILL LEARN. You will learn how the modulated by the video signal. picture is picked up by the TV camera at the There are several different types of TV cameras. The broadcast station, and how the picture and vidicon, plumbicon, and image orthicon are examples. the sound are transmitted by the TV station. You The latter is the type most frequently used. Although will learn how the TV signals are received and con- the manner in which they accomplish their purposes differ, their basic operating principles are the same. verted into and sound pictures in your TV set. The video camera, much like its photographic coun- You will also learn that the same basics are used terpart, deposits a scene through a lens on the target in transmitting TV pictures and sound as are em- Sync (Scanning) Injection ployed in FM and AM broadcast radio receivers. TO CARRIER The basic electronic principles are the same. WAVE (RF) PLIFIER TV Transmission The AM or FM radio transmitter has only the single VIDEO AMPLIFIERS task of putting sound on a carrier. The TV transmitter

must modulate two carriers, one with sound and the TIMING (SYNC) other with video (picture). The audio section is in a GENERATOR separate channel of its own. Shown in the TV block diagram here is a camera which sends a weak picture within the camera. Light rays from all parts of the signal to the video amplifier to be strengthened. The scene are focused through the lens, reproducing the output of this section is a video frequency used to image on the target. If the target were a photographic modulate a very high frequency (VHF) carrier negative, the light rays would excite deposits of light - TV Transmitter Block Diagram sensitive materials in proportion to the intensity of light, varying from white through shades of gray to ANTENNA black. A similar process occurs in a TV camera. The light -

TL HRR, Ek sensitive target receives a picture of the scene. Tiny WAVE GENERATOR on the treated target are thereby (AM)54 -216 MHZ areas chemically electrically charged in proportion to the light intensity of that part of the scene. VIDEO VISES + CAMERA AMPLIFIERS Scanning A very narrow beam of electrons is moved back ANTENNA and forth across the target from top to bottom. The MICROPHONE beam samples the intensity of the charge in each of

AUDIO AUDIO CARRIER the tiny areas. The amount of each charge indicates WAVE AMPLIFIER GENERATOR (FM) whether that portion of the scene is black, white, or some shade of gray. As the diagram shows, the target is scanned in a se- generated in the transmitter block. Superimposing the quence of 525 lines from top to bottom. A complete video (picture) on the carrier is done by amplitude scan of the target is made 30 times each second. The modulation, the method used in an AM broadcast radio same procedure is duplicated on the screen of your transmitter. The audio is frequency- modulated, just as receiver. In a TV receiver with a 17 -inch screen, the in your FM radio. electron beam in the picture tube travels across the screen at the rate of approximately 13,000 miles per TV Video Transmitter hour. In the video section, video signals from the camera A following diagram shows how this is accomplished. are amplified and fed to a power amplifier in the car- The beam moves across the target in the camera from rier generator section. Here, the carrier is amplitude- left to right, sampling the intensity of each tiny area

ELEMENTARY ELECTRONICS /September- October 1977 93 www.americanradiohistory.com be it passes. At the end of the line the beam is blanked times a second, a line- tracing frequency that cannot the rate of (shut off) and returned to the left side of the target to noticed by the eye. If it were being done at start the next line. The beam is turned on again and 30 times a second, the eye might be able to see the recognized as a flicker. This Video Camera changes, which would be process of scanning every other line is called interlaced scanning. The camera thus identifies the light and dark areas of a scene and converts this information to currents and voltages that change in proportion to the light intensity. Interlaced Scanning

CAMERA TARGET

SOLID LINES. ACTUAL S25 LINES SCANNING line. This process is continued OF NORIZ samples the second SCAN DOTTED NES,, until the, bottom of the target is reached. The beam is SEAM RETURNS blanked and returned to the upper left -hand corner again. When the beam is on and mov- to start scanning 30 COMPLETE ing from left to right sampling the intensity on the SCANS PER SECOND target, it is said to be scanning. When it is shut off and being returned to a new starting point, it is retracing. Sync Generator QUESTIONS The timing of the scanning events is very critical. at a precise point 01. The video camera target is by an The beam of electrons must begin odd - electronic beam. near the top of the camera target and scan every beam 02. How many lines does the beam trace each second? numbered line in 1/60 of a second. The electron must be blanked out precisely at the end of every line scan of all all ANSWERS and at the end of the field. A complete odd -numbered lines (or even -numbered lines) is called by an elec- Al. The video camera target is scanned a field. tron beam. When the odd -numbered field has been completed, A2. 15,750 lines per second (525 x 30). the blanked beam must be returned to a new position begin scanning the even -numbered Interlaced Scanning at a precise time to field. Each action and position of the camera beam of problems in controlling the beam and of Because must be followed precisely by similar action in your flicker to the viewer when line -by -line scan- noticeable TV receiver at home. The stage in the TV transmitter the beam is caused to scan every ning is performed, that establishes this precise timing is known as the other line. Synchronizing generator, or sync generator. the shows, the first scan starts at line As illustration The sync generator in the preceding illustration the charged areas, and is retraced to line 1, samples feeds pulse waveforms to the camera. The amplitude 3. This action continues to the bottom of the target, and timing of the pulses are such that they synchronize the odd -numbered lines. When it reaches scanning (cause all events to take place at precise time inter- Electron Beam Scanning vals) scanning, blanking, retracing, and positioning of the electron beam. The same sync pulses (for syncho- nizing the same events in the receiver) are fed, with PORT ON OF VIDEO CAMERA TA the amplified video, to another stage of video amplifiers. From this point the entire signal -video and sync 3 pulses -is passed to the final amplifier of the carrier 5 for modulation purposes. SOLID LINES = 7 from the preceding discussion, FIRST SCAN As you have learned 9 the composite video signal contains a great deal of II information. A series of video waveforms is shown. DASHED LINES = 13 Remember that a waveform is a graph of amplitude SECOND SCAN and time. CONTINUED TO BOTTOM 0 F TARGET QUESTIONS Q3. scanning skips every other line. the beam returns to the top of the plate the bottom, 04. Scanning is synchronized by a -numbered lines. Full scan, top to and scans the even What information is carried in the composite second. To scan the entire 05. bottom, requires 1/60 of a video output signal? requires two passes, which takes a plate, the beam ANSWERS total time of 1/30 of a second. On the receiver screen a new image is being presented on every other line 60 A3. Interlace scanning skips every other line.

ELEMENTARY ELECTRONICS /September- October 1977 94 www.americanradiohistory.com A4. Scanning is synchronized by the sync generator. satisfactory since the sound and video carrier frequen- A5. Video signals and sync timing pulses. cies are quite close together (the sound carrier is 4.5 megahertz higher). Video Modulation Both carriers are amplified and converted to an The video and timing pulses are placed on the car- intermediate frequency (IF). The two signals are ampli- rier frequency by amplitude modulation. fied and sent to separate audio and video detectors. In The carrier -frequency section is similar to the same the sound section, the audio component of the fre- circuits in a broadcast radio transmitter. quency- modulated wave is detected, amplified and The oscillator generates a continuous and constant sent to the speaker, In the video section, the picture frequency. The output of the oscillator is increased in signals and blanking pulses are taken from the ampli- Video Signal For Two Scanned Lines tude- modulated wave and sent to the cathode -ray (picture) tube.

BLANKING PULSE FOR SYNCHRONIZING PULSE RECEIVER - COINCIDES F OR CAMERA AND TV Receiver Block Diagram WITH CAMERA BLANKING /RECEIVER TIMING

BLAU /IMAGE

RF SECTION

CRAY TONES

WHITE EA AGE SYNC VERTICAL SYNC SEPARATOR CIRCUITS

0 HORIZONTAL I B HIGH VOLTAGE SYNC POWER SUPPLY TIME CIRCUITS IJKV+

frequency and amplitude by the multiplier and amplifier sections. In the power amplifier, the carrier is Synchronizing (sync) pulses also present in the raised to the desired power level required by the sta- video signal control the frequency of oscillators in the tion, and is amplitude -modulated by the video signal. vertical and horizontal circuits. The outputs of these Linear amplifiers are used to boost power output be- stages cause the image to appear properly synchro- yond that provided by the modulated stage. nized on the screen of the cathode -ray (picture) tube. QUESTIONS Scanning There are 525 horizontal lines in a complete picture Q6. A video signal has and dimensions. on a TV screen. Each line represents an image line 07. VHF has (shorter, longer) wave -lengths than UHF. Q8. A TV video signal is modulated. scanned by the TV camera. The entire 525 lines are called a trame. ANSWERS In the discussion thus far, video signals and blanking pulses have been fed to the ray tube 06. A video signal has amplitude and time dimensions. cathode for each scanned line of the picture waveform Q7. VHF has longer wavelengths than UHF. entering the set. The video portion of the waveform Q8. A TV video signal is amplitude modulated. controls the intensity of the electron beam, while the periodically TV Carrier (RF) Wave appearing blanking pulses shut the beam off at proper intervals called the retrace period. A is HF' COMPOSITE system needed to move the beam on the re- ARR ER VIDEO SIGNAL ceiver screen from side to side and top to bottom in synchronization (in step) with the action that takes place in the camera. Each of the video waveforms (two are shown in the diagram) represents one particular MULI INDIERSI RF POWER scan line among the 525 lines that appear on the OSCILLATOR AND AMPLIFIERS AMPLIFIERS screen of a complete picture. The camera scans every other line (interlaced scanning) for viewing ease (eliminates flicker). The re- SYN AND PICTURE INFORMATION L, ^j (FROM VIDEO AMPLIFIERI J ceiver beam must do likewise, sweeping every other line precisely in sequence with the camera. In the first pass, the beam must start in the upper left -hand corner HOW THE RECEIVER WORKS and trace every odd line, ending at the middle of the A single antenna brings both the FM sound carrier bottom line for a total of 2621/2 lines called a field (1/2 and the AM video (picture) carrier to the TV set. This is of 525). The beam must then return to the top center

ELEMENTARY ELECTRONICS /September- October 1977 95 www.americanradiohistory.com also stops the flow of elec- of the screen and sweep each even line in sequence, electrons. The control grid pulse appears. completing 2621/2 lines of the field at the right end of trons when the blanking is present, the beam the bottom line. During the time a video signal from left to right across the screen. In the process, the beam must excite the phosphores- must be moved the right side, the blanking cent screen with the corerct intensity indicated by the When the beam reaches the beam moves back corresponding portions of the video waveforms. At the pulse shuts off the electrons and end of each line, the beam is blanked and must be to start the next line. line of the rapidly returned to the left to start the next Moving The Beam Across The Screen picture. When the beam reaches the bottom of the screen, it must be blanked again and rapidly returned to the correct position (left or middle) at the top to sweep the next field. It must complete a field (2621/2 VIEWED FROM ABOVE lines) in precisely 1/60 of a seocnd and a full frame (complete picture) in 1/30 of a second. RETRACE QUESTIONS GUN 09. The start and the position of each scan line on on the CRT screen are controlled by the lines to a field and ... fields to a 010. There are ... HORIZONTAL frame. DEFLECTION COILS LEFT ANSWERS the of each scan line on A9. The start and position A horizontal -deflection coil through which the neck are controlled by the sync the CRT screen of the tube is inserted moves the beam from side to pulses. side. Current moving through the coil sets up a a field and two fields to A10. There are 2621/2 lines to magnetic field which has an attracting and a repelling a frame. effect on electrons. the is its effect on Moving the Electron Beam The stronger the field, greater the beam. To increase the strength of the field requires We know that a negative voltage repels and a posi- an increase in current through the coil. The illustration tive voltage attracts electrons. The cathode -ray tube shows the beam during retrace. (CRT) uses this effect to send an electron beam to the The change in strength of the magnetic field during screen and control its movement. a sweep must coincide with the time duration of the Tube Cathode Ray (Picture) scanned line. A gradual rise of current within the coil during this time period accomplishes this. The starting ELECTRON time is triggered by the sync pulses that ride on the ELECTRON HORIZONTAL BEAM at the GUN COILS blanking pulses. If the current decreases rapidly VERTICAL the blanking pulse), the sud- COILS end of each line (during den drop in magnetic field strength returns the beam to the left very quickly. VIDEO A similar magnetic field is set up by a second coil SIGNAL (the vertical -deflection coil) which controls the move- .1 ment of the beam line by line from the top of the screen to the bottom. On completion of a field (2621/2 lines), the beam quickly retraces to the top. QUESTIONS 011. The sweep of the receiver beam must be with the camera beam. PHOSPHORESCENT beam in the CRT is generated by SCREEN 012. The electron an to the screen of the CRT by The basic construction and connections of a mag- 013. Electrons are drawn netically deflected CRT are shown. At the left end an a Q14. move the CRT beam. electron gun shoots a narrow stream of electrons in current through a deflection coil toward the screen. To speed the electrons on their 015. An increase (increases, decreases) the magnetic field. way, the inner surface of the flared portion of the tube has a conductive coating energized with a voltage that ANSWERS is several thousand volts positive with respect to the The sweep of the receiver beam must be syn- electron source. All. chronized with the camera beam. The CRT is connected to the output of the last video beam in the CRT is generated by amplifier from which it receives the video and blank- Al2. The electron an electron gun. ing signals. The CRT control grid, which controls the Electrons are drawn to the screen of the CRT by number of electrons, responds to the varying amplitude A13. a positive voltage of thousands of volts. of the video and releases the required quantity of

ELEMENTARY ELECTRONICS /September- October 1977 96 www.americanradiohistory.com Sync Control ANSWERS A16. Timing of the magnetic field developed in the FROM VIDEO horizontal and vertical deflection coils is con- AMPLIFIER trolled by sync pulses extractea from the video PICTURE waveform. TUBE A17. The sync separator separator separates the narrow and wide timing pulses from the video SYNC waveform. The narrow pulses control horizontal IFIERS1 AMPL deflection and the wide pulses control vertical deflection. A18. Horizontal -sync pulses occur during the horizontal blanking portion of the video waveform. VIDEO AND SYNCHRONIZING Sweep Circuits SIGNALS The two sweep circuits (horizontal and vertical) generate a linear rising voltage each time they receive a sync A14. Magnetic fields move the CRT beam. pulse. The horizontal -sweep circuit is triggered 2621/2 A15. An increase in current through a deflection coil times during the same time the vertical -sweep circuit is increases the magnetic field. triggered once. Horizontal sweep is produced by an oscillator which generates a slowly rising and rapidly Sync Control Circuits decaying sawtooth waveform, whether the set is tuned The beam movement is accomplished by steadily to a transmitting station or not. This accounts for the increasing the current flow in each of the deflection raster (lines on the screen when the TV receiver is coils during precise time intervals. The starting times on but no signal is being received. for these intervals are controlled by the sync pulses. Horizontal Sweep Circuit Video waveforms arrive at the sync separator from the video amplifier. There is one narrow sync pulse for each line of scan. This pulse is intended to control the starting time of each horizontal sweep across the RISE TIME DECAY TIME screen. When one field of 2621 lines has been completed, the video waveforms are followed by a sync pulse many times wider than the horizontal sync pulses. This wide pulse is the trigger that develops a verti- HORIZONTAL sweep to move the beam from line to line down the FROM SYNC TO face of the screen. Every other vertical sync pulse SEPARATOR SWEEP HORIZONTAL - DEFLECTION starts in the middle of a video waveform, accounting COIL for 2621/2 lines in each field of interlace scanning. an* _p The illustration shows the comparative widths of the horizontal and vertical sync pulses and the relative starting times of the second and third fields. The sync pulses are removed from the complete video waveform The purpose of sync pulses is to trigger oscilla- by a sync separator. tors to start at the same time as the line scan in the The narrow and wide pulses are distributed to the camera. Capacitor and resistor combinations convert appropriate sweep circuits (horizontal and vertical) the oscillations to the sawtooth waveshapes shown in after sync separation accomplished by capacitor and the diagram above. Rise time of the sawtooth causes resistor combinations which can distinguish between the current in the horizontal -deflection coil to increase voltage waveforms with short time durations and those gradually, moving the beam across the screen in step with long durations. The short sync pulses are sent to with the line scan in the camera. At the end of the line, the horizontal sweep circuit and the long pulses to the coil current decreases rapidly, returning the beam vertical sweep circuit. (which is now blanked) to the left of the screen. There are 525 lines to each frame, so the frequency of the horizontal oscillator must be 15,750 cycles per second QUESTIONS (525 x 30). 016. Timing of the magnetic field developed in the The vertical sweep oscillator and amplifier are al- and deflection coils is con- most identical to those in the horizontal sweep section. trolled by .... pulses extracted from the video The main difference is that the frequency of oscilla- waveform. tion is much lower -60 times a second, to match the 017. The sync separator separates the narrow and frequency at which each field is swept. The rise time wide timing pulses from the video waveform. The (plus a short decay time) of the vertical sawtooth lasts narrow pulses control deflection and the for 1/60 of a second before another vertical sync wide pulses bontrol deflection. pulse arrives to start the next waveform. Gradual in- 018. Horizontal sync pulses occur during the horizontal crease in current in the vertical deflection coil moves portion of the video waveform. (Continued on page 104)

ELEMENTARY ELECTRONICS /September- October 1977 97 www.americanradiohistory.com LITERATURE

LIBRARY323. Get Lafayette Radio's "new look" 1977 catalog 344. For a packetful of material, send for SBE's 301. Get acquainted with the new EICO products, _ mobile t^.designed for the professional technician and elec- with 260 pages of complete electronics equipment. material on UHF and VHF scanners, CB -scan TV tronics hobbyist. Included in brochure are 7 IC It has larger pictures and easy -to -read type. Over transceivers, walkie- talkies, slow systems, project kits, EICO's "Foneaids," security products 18,000 items cover hi -fi, CB, ham rigs, accessories, marine -radios, two -way radios, and accessories. test equipment and tools. and many varied kits. 345. For CBers from Hy -Gain Electronics Corp. there 327. Avanti's new brochure compares the quality is a 50 -page, 4 -color catalog (base, mobile and 302. International crystal has illustrated folders con- difference between an Avanti Racer 27 base loaded marine transceivers, antennas, and accessories). taining product information on radio communica- mobile antenna and a typical imported base loaded Colorful literature illustrating two models of moni- tions kits for experimenters (PC boards; crystals; antenna. tor- scanners is also available. transistor RF mixers & amplifiers; etc.). new is available from McGee 328. A free catalog 350. Send for the free NRI /McGraw Hill 100 -page Regency has a new low cost /high performance Radio. It product bargains. 303. contains electronic color catalog detailing over 15 electronics courses. UHF /FM repeater. Also in the low price is their 329. Semiconductor Supermart is a new 1977 cata- Courses cover TV -audio servicing, Industrial and channel monitoradio scanner that offers 5 -band 10- log listing project builders' parts, popu'ar CB gear, digital computer electronics, CB communications performance. and test equipment. It features semiconductors - servicing, among others G.I. Bill approved, courses 304. Dynascan's new B 8 K catalog features test all from Circuit Specialists. are sold by mail. eequipment for industrial labs, schools, and TV 330. There are nearly 400 electronics kits in Heath's 352. Send for the free descriptive bulletin from servicing. new catalog. Virtually every do -it- yourself interest Finney Co. It tells all about their new auto FM radio is 305. Before you build from scratch, check the Fair included -TV, radios, stereo and 4- channel, hi -fi, signal booster (eliminates signal fading). Radio Sales latest catalog for surplus gear. etc. 353. MFJ offers a free catalog of amateur radio 331. E. F. Johnson offers their CB 2 -way radio cata- of latest mo- equipment -CW and SSB audio filters, electronic 308. Get Antenna Specialists' catalog log to help you when you make the American vaca- acces- components, etc. Other lit. is free. bile antennas, test equipment, wattmeters, tion scene. A selection guide to the features of the sories. various messenger models will aid you as you go 354. A government FCC License can help you qualify for a career in electronics. Send for Infor- 307. Want a deluxe CB base station? Then get the through the book. mation from Cleveland Institute specs on Tram's super CB rigs. 332. If you want courses in assembling your own of Electronics. TV kits, National Schools has 10 from which to 355. New for CBers from Anixter -Mark is a colorful Is the word for Xcelite's 9 different 308. Compact choose. There is a plan for GIs. 4 -page brochure detailing their line of base station of midget screwdrivers and nutdrivers with sets 333. Get the new free catalog from Howard W. and mobile antennas, including 6 models of the handle to increase length and torque. "piggyback" Sams. It describes 100's of books for hobbyists famous Mark Heliwhip. A handy show case serves as a bench stand also. and technicians -books on projects, basic elec- 358. Send for Continental Specialties new bread- tronics and related subjects. 310. Turner has two booklets on their Signal Kicker boarding prototest devices. They vary in prices antennas. They give specifications and prices on 334. Sprague Products has L.E.D. readouts for those from a mini -budget kit at $19.95. Featured is the their variety of CB base and mobile line. Construc- who want to build electronic clocks, calculators, new logic monitor, giving information on what it tion details help in your choice. etc. Parts lists and helpful schematics are included. does, how it works, and how to use it. 335. The latest edition of the TAB BOOKS catalog line of base, mobile 311. Midland Communications' describes over 450 books on CB, electronics, broad- 357. Daga Scientific Instruments offers a 16-page marine transceivers, and hand -held CB equipment, casting, do- it- yourself, hobby, radio, TV, hi -fi, and booklet on how to build an electronic thermometer accessories scanning monitors, plus a sampling of CB and TV servicing. with control. Included is an introductory course on are covered in a colorful 18 -page brochure. thermocouples, schematics and many applications. 337. Pace communications equipment covers 2 -way 312. The EDI (Electronic Distributors, Inc.) catalog radios for business, industrial and CB operations. 358. PixTronics announces its new Model 200 Super is updated 5 times a year. It has an index of manu- Marine radiotelephones and scanning receivers are Sensitive Electronic Darkroom Exposure Meter, facturers literally from A to X (ADC to Xcelite). also in this 18 -p. book. used to determine the correct exposures of all Whether you want to spend 29 cents for a pilot - 338. "Break Break," a booklet which came into black- and -white and color negatives. Useable with light socket or $699.95 for a stereo AM /FM receiver, existence at the request of hundreds of CBers, con- any enlarger. you'll find it here. tains real life stories of incidents taking place on America's highways and byways. Compiled by the 359. Electronics Book Club has literature on how to Progressive Edu -Kits Home 313. Get all the facts on Shakespeare Company, it is available on a first get up to 3 electronics books (retailing at $58.70) Radio Course. Build 20 radios and electronic cir- come, first serve basis. for only 99 cents each ... plus a sample Club News cuits; parts, tools, and instructions included. package. 342. Royce Electronics has a new 1977 full line 316. Get the Hustler brochure illustrating their com- product catalog. The 40 -page, full -color catalog 380. Cornell- Dubilier has a 4- color, 4 -page, bro- plete line of CB and monitor radio antennas. contains their entire new line of 40-channel AM and chure on its Ham II, CD -44, and Big Talk rotor SSB CB transceivers, hand -helds, marine communi- communication systems. Exploded half tones detail their com- 317. Teaberry's new brochure presents cations equipment, and antennas and accessories. interior rotor construction, and tables list specs. plete lines of CB and marine transceivers and scanners for monitoring police, fire and other public service frequencies. i ELEMENTARY ELECTRONICS September /October 1977 Chemical 318. GC Electronics offers an "Electronic Box 1849, G.P.O. Handbook" for engineers and technicians. It is a Void After February 16, 1978 "problem solver" with detailed descriptions, uses New York, NY 10001 of 160 chemicals compiled for and applications Please arrange to have the literature whose numbers I have circled below sent to me as electronic production and packaging. They are used soon as I am 500 10 for all typas of electronic equipment. possible. enclosing for each group of to cover handling. (No stamps, please.) Allow 4 -6 weeks for delivery. 319. Browning's mobiles and its famous Golden Eagle base station, are illustrated in detail in the 301 302 303 304 305 306 307 308 310 311 312 313 new 1977 catalog. It has full -color photos and specification data on Golden Eagle, LTD and SST 316 317 318 319 320 321 322 323 327 328 329 330 models, and on "Brownie," a dramatic new mini - mobile. 331 332 333 334 335 337 338 342 344 345 350 352 320. Edmund Scientific's new catalog contains over 353 354 355 356 357 358 359 360 4500 products that embrace many sciences and fields. 300 Enter my subscription for 9 issues at $5.97. Check enclosed. Add $1.00 for Canada and all other coun ;ries. H71015 321. Cornell Electronics' "Imperial Thrift Tag Sale" Catalog features TV and radio tubes. You can also find almost anything in electronics. NAME (print clearly) 1977 catalog colorfully illus- 322. Radio Shack's ADDRESS trates their complete range of kit and wired prod- for electronics enthusiasts -CB, ham, SWL, ucts STATE ZIP hi -fi, experimenter kits, batteries, tools, tubes, wire, CITY cable, etc. ad

98 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com while the cement dries. Solder the ends Antique Radio of the tube pins, being sure to heat the (Continued from page 79) pins hot enough that the solder will flow down into the pins. Do not use exces- coldest part of your freezer for several sive solder, for it may run down inside hours then remove it and push the base the base and short the wires together. MUTH only down into some boiling water. The Use a small file to dress the of the You'll enjoy your work as a Locksmith ends because it Is more fascinating than a uneven coefficient of expansion will pins to a round surface the pins will hobby-and highly paid besides!! You'll so go on enjoying the fascinating work, year after year, in good times or bad sometimes break the cement loose. I go into a socket easily. "Was newer so en. because you'll be the man in demand thusd and de. in an overgrowing field offering big usually have success this way, but as a Now We Test It. To test the con- lighted with lessons pay jobs, big profits as your own boss. in my entire life. I last Train at Home -Earn Extra Right resort you could use a solvent. verted 864/WD11 in a regular four -pin grossed over $3,000 $55$ Away! Send for FREE booklet today! Next take a double -cut file and file tube socket you must n one year just make an adapter. working weekends." LOCKSMITHING INSTITUTE away the solder from the ends of the The easiest way to do this is to remove Rocky Ors Div. Technical Home Study Schools Azusa, Ca ifornia pins. With a soldering iron or gun heat a four -pin base from an old tube. Solder Dept1472- o!!- Little Falls, R.I. 07424 the pin tip and flip the tube to throw flame pieces of flexible wire about 6- inches (Please Print) the melted solder out of the pin. You long into the tube pins. Solder clips Address should now be able to see the lead wires with insulators to the opposite ends of City /state /2io through the holes in the ends of the the wires. Identify each clip as to grid, 0 Check here if Eligible for Veteran Training ' pins. When all four wires are un- plate, and filaments. Connect the clips soldered you will be able to pull the to the proper pins, set the tube tester bulb loose from the base. Whatever filament selector switch to 1.1 volts, and you do, don't forget which wires go to set the other knobs just the same as OE McGEE'S the plate, grid, and filaments. You can you would for a 30, and test in the identify the filament wires with a low - usual manner. If the lowest filament BIG SPEAKER CATALOG range, low-current ohmmeter, but if voltage on your tube tester is 1.5 volts 1001 BARGAINS IN you loose the grid and plate wires you solder a 1.5 ohm, 1/2-watt or larger in SPEAKERS - PARTS -TUBES - HIGH FIDELITY will have to look inside the bulb to series with one filament lead. This will COMPONENTS - RECORD CHANGERS trace the wires to their respective tube reduce the voltage to 1.1 volts. Tape Recorders- Kits - Everything in Electronics elements. The 864 will have two grid If you decide to convert a 30 or 1901 McGee Street, Kansas City, Missouri 64108 leads inserted into one pin. You will 1H4G to a WD11 replacement follow find the lead wires are an alloy that the same general directions, only use bonds readily to glass, but is difficult to the correct wiring and filament voltage PARTS! TUBES! solder to. Tin the leads for at least a for the tube you are converting. half inch when tit you reassemble the bulb If You Need. Help. For those of you 1RNiLt 36`rtube to the base. You may need to polish who are hew Color e "all thumbs" or do not have t11be ORDER FREE the C atalog 33ç IF NOI SHIPPED leads with sandpaper and use a the proper tools you can buy the pins vt 1f. Yee 'temt .N ! (1 ". OF 100 IN 24 HOURS' flux when tinning the leads. already made or buy a tube base with You are now ready to remove the the pins already staked into the proper VI f UNIVERSITY AVE SAN DIEGO, CALIF 92105 two larger filament pins from the tube holes. Write to Antique Radio Parts, -base. If you have access to a drill press P.O. Box 42, Rossville, IN 46065 for a HIGHLY this will be easy. Otherwise use a hand- brochure showing the necessary parts PROFITARL1 ONE-MAN held electric drill. Use a no. 28 drill bit with prices. If you need 30s or a 864/ ELECTRONIC FACTORY and carefully drill out (from the inside VT24 tube write to George Haymans, Investment unnecessary, knowledge not required, of the base) most of the staked portion Box 468, Gainesville, GA 30501 for his sales nandlsd by professionals. Postcard brings of the brass pin. With a sharp pick re- facts about this unusual opportunity. Write today! list of tubes and parts. Be sure and send Berta- ' ,Box 248, Walnut Creek, CA 94597. move the remaining parts of the stak- an SASE to either of these sources or ing, grasp the pin with a pair of pliers you may not get a reply. gently pull and twist until the pin So long for now! I hope I have given Now E Bonds pay 6% interest when held to maturity of destroyed you a 5 years (41 g96 the first year). Lost, stolen or comes out. If have lathe you can you some useful information on re- Bonds can be replaced if records are provided. When make the new pins that you need or you placing those nearly impossible tube needed, Bonds can be cashed at your bank. Interest is not subject to state or local income taxes, and federal can purchase them from the source types. Believe me, it is well worth the tax may be deferred until redemption. named at the end of this article. Now not inconsiderable effort. The thrill of that you have removed the pins you are receiving modern -day broadcasts on an ready to reassemble the tube. Insert the antique receiver-and a receiver which is large pin into its hole in the base, and operating exactly as it did in the old using a punch with a 90- degree point days -is something you have to experi- carefully flare the pin until it fits tightly. ence to truly understand. Somehow, Do the same with the smaller pin. Be receiving broadcasts on the newer, state - sure you stake them tightly into the of- the -art sets cannot compare to reliv- proper holes. The drawing shows the ing the old days when it was a DX like FA. base with the pins up. Run a bead of catch just to hear your home -town sta- cement around the glass bulb and insert tion, though many antiques are capable the previously- tinned leads into the of surprisingly sensitive and selective . stock proper pins. Remember the plate pin is operation. All in all, this is a hobby the large pin, across from it is the grid which has appeal for young and old in America. pin. The other two pins are for the alike. filament. Use masking tape to hold the See you next time with more antique 200 years at the same location. bulb and base together tor 24 hours radio news and views.

ELEMENTARY ELECTRONICS /September- October 1977 99 www.americanradiohistory.com LEDIT -checks your SCRs and diodes (Continued from page 92) ANNOUNCING LEDIT READOUT TABLE

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a c g x x normal turn -off a ov 's MISCONNECTIONS Sa g c a x x SCIENCE g c a x x x pICT10Nt . c a g x x

c a g x x R. a g c x x 1 GORDON DICKSON x ! a g c x BISHOP x IL c g a x ISAAC t ASIMOV c g a x x I KEVIN Jr x LED I O DONNELL, g a c x Clear 4 DEAN HLIN may be on MQpN D weak VING LED g a c x x Clear goes out 192 PAGES IN EACH ISSUE DIODES Reserve your subscription and mail your today, we'll a c x x normal

copies to your doorstep. a c x x open c a x x shorted Be sure you don't miss this c a x x normal "first" by one of the world's Use the above table to interpret LEDIT's displays. For further discussion of the leading science fiction writ- way by which LEDIT reads out, see pages 91 and 92. ers. better to be safe than sorry. times and see if the indicator D3 lights In thousands of parts tested I've every time, or just part of the time. never had a false indication except in Part -time turn -on indicates a definite the case of a few rare dv /dt turn -ons. dv /dt situation. Full -time turn -on usu- ISAAC ASIMOV'S When this happens, here's what to do. ally indicates a short. Thats all there SCIENCE FICTION MAGAZINE is to it! Box 1855 GPO Just interrupt the power with S2 several New York, NY 10001 Finally, for those who want a quick, I enclose $4.00 which includes New Heath Computers convenient way to save programs for for a 4- shipping and postage (Continued from page 47) future use Heathkit also introduced issue subscription. their model H10 Papertape Reader/ standard In Canada, all other countries, (teletype) to 9600. Punch. This device punches at the standard $5.00. If you need hard copy -a printed 1 -inch teletype tape record- here's the biggie: Heathkit will TTY speed of 10 characters per sec- Name sell the DEC Writer II Keyboard Print- ond, but unlike standard TTY readers (please print) er Terminal. For those of you who which read back at 10 cps the HI Address don't know why we call it the biggie; reads at 50 cps; you can load programs the DEC Writer II is the Cadillac of into your Heathkit computer at five City teletype -style terminals. It is probably times the punching speed. The punch independently and the most desired peripheral in any and reader operate State Zip A copy computer installation. (Peripheral is an can be used simultaneously. is standard accessory input or output, or input/ mode for tape duplication The mail order price in output device for a computer.) parallel TTL. ELEMENTARY ELECTRONICS /September- October 1977 100 www.americanradiohistory.com kit form is $350. use with OSI Challengers, including Summing Up. Overall, the wedding matching case and power supplies, for of Heathkit and DEC has been bold, $990. OSI's floppy disk bootstrap prom dramatic, and exciting. It has com- allows the owner of any OSI system to use floppy pletely changed the development and his disk immediately on power up marketing and is available for $29 with either version JEJJ' of personal and small -sys- of the 4708. Ohio Scientific Instrument, tems computing equipment in that 11679 Hayden Street, Hiram, Ohio 44234. (r' small systems will no longer be scaled - Circle 52 on Reader Service Coupon for !! down versions of commercial comput- more information about this product. U \]1 ers. In particular, having a PDP -11 in your home or office isn't a compromise 358 Ways To Save On between commercial and personal computers: most consider it among the Instruments, CB, very finest in minicomputers. And the Heathkit -DEC peripherals ate in the Burglar Alarms, same class. Automotive & Hobby For additional information circle No. 31 on the reader's service coupon. Electronics! Computer New Products The more you know about electronics, the more you'll appreciate EICO. Every EICO (Continued from page 64) product is designed to provide you with the most pleasure and quality performance for prefabricated fifty line interconnecting your money. The fact that more than 3 cable. An introductory special consisting million EICO products are in use attests to of a fully assembled drive and cable har- their quality and performance. ness, 6502 disk operating system, and a lousy 25 controller board in kit form costs $599. The "For a cent beer? No, won't change the "BUILD-IT- YOURSELF" and save up to drive is also available fully assembled I channel!" for 50% with our famous electronic kits. switches for Channel Selector, Vol- For the latest EICO Catalog and name of nearest CB XCVR Checkout ume, Squelch /PA, Noise Blanker, EICO Distributor, check reader service card or send 500 for fast first class mail service. (Continued from page 53) ANL, External CB (CB signal to PA EICO -283 Malta Street, Brooklyn, N.Y. 11207 speaker). Standard accessories are Leadership in creative 17 microphone, . mobile mount, DC electronics since 1945. E/CO; power cable. CIRCLE 2 ON READER SERVICE COUPON Receiver Section Test: Relative Sensitivity for 85% Input Sensitivity 0.6 i V Old Radio Adjacent Channel Rejection 62 dB AGC Action 9 dB Treasures Input Level for S9 70 µV Transmitter Section Test: AM RF Output 3.9 watts CIRCLE 70 ON READER Modulation to 85% yes SERVICE COUPON Modulation -36 dB Modulation Limited to 100% yes ation. Delta tune 2+:1.2 kHz provided. Editorial Remarks The Midland 77- Power supply 12 to 13.8 VDC with 882 has a relative reading S- meter, DON'T LOSE OUT positive or negative ground. Overall double conversion receiver, external Our books are your key! dimensions are 21/4 -in. h x 6% -in. w and PA speaker jacks, and S /RF out- VINTAGE RADIO, 1887 -1929: Pictorial x 77/s -in. d. Front panel controls and put meter. story of pioneer days, 1,000 photos, 263 pages. $10.95 hard -cover, $8.95 soft. magnetic receiver is claimed to mask A FLICK OF THE SWITCH, 1930 -50: Fun picture reference of home, military, Loud and external noise; and the voice signal is Clear, GB Ham, professional radio -TV- electronics, (Continued from page 74) amplified by a small, in -line variable 312 pages. $10.95 hard -cover, $8.95 soft. amplifier. Specs for the magnetic micro- RADIO ENCYCLOPEDIA, Gernsback's phone: Sensitivity, -48 dB; frequency 1927 classic beautifully recreated, 175 CB -SMC features a push -to -talk switch response, 100 to 4000 Hz. Specs for the pages. $14.95 hard- cover, $10.95 soft. which mounts onto the auto turn signal single magnetic driver: Impedance, 8 RADIO COLLECTOR'S GUIDE, 1921 -32: or gear shift. The mike is powered by ohms; sensitivity, 103 dB; frequency re- Data book with 50,000 facts on 9,000 an AA battery, and the earphone is sponse, 200 to 8000 Hz. models by 1,100 makers, 264 pages, $6.95. equipped with an anti -blast circuit. The Another headset by Telex that in- 1926 -38 RADIO DIAGRAMS: Beitman's CB-SMC can be used with either relay cludes a full -size, cushioned earphone classic of 600 models, 240 pages, $7.00. or electronic switching radios. is model CB -1200 ($59.95). Specs for IMMEDIATE DELIVERY! TODAY Telex CB -88 ($69.95) is a the ceramic mike: Sensitivity, dB; SEND to Vintage Radio, Dep't E, The light- -66 Box 2045, Palos Verdes, Ca. 90274. weight headset that can be worn by frequency response, 100 to 5000 Hz. We pay postage. Calif. residents add 6%. means of a headband or by clipping to Specs for the single dynamic driver: eyeglasses with an adapter. The headset Impedance, 8 ohms; sensitivity, 103 dB; weighs less than 3 ounces. The single frequency response, 100 to 8000 Hz. Year -round Fun!

ELEMENTARY ELECTRONICS /September- October 1977 101 www.americanradiohistory.com burglar -fire alarm catalog FOREIGN FM DX TARGETS Hi -Fi DX BERMUDA (Continued front page 86) ZBM -FM, Hamilton, 89.1 -FREE! ZFB -FM, Hamilton, 94.9 CUBA Foreign DX Too! While most FM DX MORE THAN CMQ -FM, Havana, 90.5 is restricted to the United States and Santa Clara, 90.5 900 PRODUCTS CMHW -FM, Canada, some foreign DX is possible. DOMINICAN REPUBLIC detectors, DXers within 1000 miles of the Mexi- HIZ -FM, Santo Domingo, 89.1 controls, can border have a shot at logging HION -FM, Santo Domingo, 92.5 HIJP -FM, Santo Domingo, 94.9 sounders, Mexican stations. DXers in the South- can to in the HIJB, Santo Domingo, 95.7 locks, east expect hear stations Caribbean. Bermuda is frequently re- HAITI tools -FM, Port Au Prince, 88.1 ported from states on the Atlantic coast. 4VUE JAMAICA and Such. Any radio Equipment Radio Jamacia, Spur Tree, 90.5 EVERYTHING NEEDED capable of receiving FM can be used Jamaica Broadcasting Corp., for sporadic -E work. In fact, many TO PROTECT HOME, Coopers Hill, 91.1 DXers actually prefer portables and Corp., BUSINESS, INSTITUTION Jamaica Broadcasting rabbit ears antennas due to their direc- Montego Bay, 92.1 Huge selection of high quality professional tional characteristics. The strength of Radio Jamaica, Coopers Hill, 92.7 alarm products. 64 fact -filled pages with most sporadic -E skip makes high sensi- the same general area should also be detailed specs, diagrams, technical notes. tivity and high -gain antennas unneces- heard, unless you have locals on their Products range from basic switches, con- if you have the trols, bells, sirens to most sophisticated sary. frequency. Therefore, detectors - radar, modulated or passive For serious tropo work most DXers relatively stable tropo signal of a station infrared, microwave, ultrasonics, ion, data prefer an outside antenna as high as a few hundred miles away, check the links using pulse code multiplex, FSK possible. The aim here is that the an- latest edition of White's Radio Log (an radio, automatic phone dialers, leased line connections and display panels. Full sel- tenna reach into the tropospheric duct. exclusive feature of our sister publica- ection of tools, relays, wire, foil, terminals, DX Strategies. Since FM DX open- tion, COMMUNICATIONS WORLD) for books. ings do not last as long as those on other stations in the same general area. WRITE FOR FREE CATALOG TODAY! medium or short wave, a strategy for Tune to their frequencies and odds are (Outside U.S.. send $1.00.) DXing must be devised. For sporadic-E, they'll be heard! it is wise to listen only long enough to Sure They QSL! FM broadcasters are mountain west alarm get sufficient material for a verifiable excellent verifiers. In fact, your author box 10780phoenix, az 85064 report. Once this is done, tune to an- has found that they are generally better (602) 263 -8831 other frequency. You may like to send verifiers than standard AM broad- hour -long reports to shortwave broadcasters. CIRCLE 11 ON READER SERVICE COUPON casters, but that's a luxury that you can- Forget all about SINPO, QSL, QRM, not afford FM. 73, and all the rest of that SWL lingo. ELEMENTARY ELECTRONICS on Tropo DX openings often last for FM broadcasters have no idea what it INDEX TO ADVERTISERS several hours or even days. Also, tropo means, so write your report in plain affects the entire 88 to 108 MHz English. Reports should be addressed to READERS PAGE the chief engineer, and always include SERVICE NO. COMPANY NAME NUMBER equally, in contrast to sporadic -E and its maximum usable frequency. In addi- return postage if you want a QSL. 6 A P Products 10 tion, if tropo is in from a certain area Record titles may be good material 5 Acoustic Fiber Sound 6 24 Avanti 30 on one frequency, all other stations in for reports to shortwave stations, but 20 B &F Enterprises 22 American FM stations don't keep lists 7 B &K Precision, Div. Dynascan 24 FM DX REPORTING DO'S AND DONT'S Barta 99 of songs played. Include music played - Cleveland Institute of Electronics 108, Cov. 3 Do enclose return postage with for it can't hurt. The best 8 Cobra 11 anyway, 29 Continental Specialties 40 each report. material is commercials and public ser- Cornell 99 Do address your report to the Chief R. L. Drake 8 vice announcements you heard and the 16 Engineer. 28 R. L. Drake __ 35 time when you heard them. Commercial 39 Edmund Scientific 7 Do use plenty of readily verifiable 2 Eico 101 broadcasters must keep lists of these 30 Formula International, Inc. 33 material in your reports, such as - Gilfer Associates 35 names of announcers, commercials and the time at which they are aired. - Heath Co. 54 -57 Other good items are announcer's name, 1 Heath Co. 82 -85 and public service announcements, International Correspondence Schools .... Coy. 2-3 station slogans, song ratings on rec- that station's record survey, and any- 9 International Crystal 34 13 Kester Solder 14 ord surveys, and any other item that thing that seems to be unique to that - Locksmithing Institute 99 seems to be unique to that station. station. Keep your reports concise and McGee 99 23 Motorola Inc. 18 Do describe reception quality in to the point. 19 Motorola HEP 16 plain English. Include details on your listening gear. 11 Mt. West Alarm 102 - N.R.I. Schools 26 -29 Do politely request a verification. If other stations were audible from the 36-39 National Technical Institute Do ask if any reports more distant same general area, you might want to 12 New -Tronics 17 than yours have been received. 38 OK Machine & Tool Co. _ 23 mention that fact. Be sure to ask if they 21; Optoelectronics ._ 20 DON'T use any SWL jargon as 14 President 15 have received any reports more distant 26 Progress Inc. 21 "QSL," "QRM," or the SINPO code. 15 Progressive Edu -Kits 5 DON'T rely solely on song titlesor than yours, for quite often you will Quality Terminals 34 35 a find yourself the most distant reporter 34 Quest Electronics 12 list of records played to prove your Radio Shack Coy. 4 reception. to a station! - Radio Shack 25 Radio Shack 31 DON'T demand a verification -ask Is there anyone who doesn't have a - Radio Shack 103 for one! radio capable of receiving FM some- Scelbi 19 36 DON'T report a unless you 17 Shakespeare 13 station where in their home? There's no reason Sinclair Radionics 32 are absolutely certain that you indeed then not to start FM DXing, so begin 18 Tab Books 9 heard it! If you can't be certain, re- 25 Telco 104 today. Discover what DXing's in crowd 41 Vector 14 port it as a tentative reception. - Vintage 101 has found out! 102 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com t*9 The ArcherKit Thermo Meter

An easy -to -build electronic thermometer that monitors both indoor and outdoor temperatures on a big 41/2" meter!

ArcherKitR obsoletes ordinary thermometers. Now you can monitor indoor or outdoor temperatures at a glance. All you do is push a button for big, accurate readings in fahrenheit and celsius degrees. A remote sensor moults outdoors or even in another rcom, basement or garage. And the dual -range scale reads temperatures from 40 to +120 °F and 40 to +50 °C. It's a low -cost introduction tc kit building you'll be proud to own. Solid -state circuitry assures h gh accuracy and years of service. Handsome simulated walnut -grair housing has keyhole slots for easy wall mounting, or place it or a desk or shelf. Operates on a 9V battery so you can use it anywhere. With instructions for easy assembly - build yourself a nice addition to home or office. Only 26.95*

FREE! New 78 Catalog * Retail prices may vary at individual stores and dealers Prices and products may vary in Canada. Come in for your copy and see what's íeady gePgS,-; new in electronics. 164 ftadue cages, 100 in full color. $haek A TANDY C)M,ANV FORT WORTH, TEXAS 76107 2000 exclusive items. OVER SOD LOCATIONS IN NINE COUNTRIES ELEMENTARY ELEDTRONICS /September- October 1977 103 www.americanradiohistory.com and reload into the computer. Some to get one, because the waiting list for Phoning the Future personal computing hobby recorders a new one dircet from Teletype is (Continued from page 45) run 1200 baud, and that 10 or 15 months and months) make certain you minute program can be saved and load- get it from a company specializing in which is less than one -third the time ed in a few seconds. (There are even rebuilt models, such as National Tele- of the 110 baud stop bits.) higher baud rate recorders.) type. Baud rates can be intermixed for Summing Up. Your first requirement If you opt for a CRT terminal the storage. Assume you have a Southwest for both personal and time -share com- proven one is the ACT -1; if you want Technical Products MC6800 personal puters is the terminal. With the personal to go the build -it- yourself route South- computer such as the one E/E will use computing marketplace growing at a west Technical Products is probably for our personal computing series. You rate exceeding Jack's beanstalk there your best bet at this time. might type in your program using a 110 are more and more ads from more and For modems, Omnitec is considered baud model 33 teletype. Allow for cor- more companies offering surplus TTYs by many the industry's workhorse. A rections, proofing and changes and as- and CRT terminals, both kit and wired. used model 701A is available for about sume you have worked'one hour loading Like the early days of anything, many $150 and handles both TTY and RS- the program. The final program -error won't be around tomorrow when you 232 inputs. They have newer TTY free -if punched out on paper tape need service or parts, and some of what models available in both semi -kit and through the TTY might take 10 or 15 will be sold won't work too well. In wired versions for prices between $100 minutes to load it back in the next time selecting a terminal, stick to the well - and $160. you want to use it. But you can have a known brands from companies that In later articles we will cover other "hobby standard" 300 baud recorder have deserved reputations. For example, equipment such as TTY tape readers, connected to the computer, and instead you can always get parts and service for high baud rate recorders, splicers, stor- of dumping the program out to the a model 33 TTY at reasonable prices. age systems, etc. TTY you dump to the recorder at three This is not necessarily true of any The age of personal computing is times the TTY speed. The recording will other TTY. If you're purchasing a used upon us so you might as well climb take only some 3 or 4 minutes to save model 33 (which is about the only way aboard at the beginning.

Basic Course-Transmitting and ReceivingTV QUESTIONS (Continued from page 97) 019. What is the horizontal sync pulse frequency? 020. What is the frequency of the vertical sync pulses? the beam from the top to the bottom of the screen. The ANSWERS decay of the vertical sawtooth waveform brings the A19. The horizontal sync frequency is 15,750 Hz. beam back to the top in time for the next sync pulse. A20. The vertical sync frequency is 60Hz. WHAT HAVE YOU LEARNED COMMUNICATOR SERIES CB /I-AM ACCESSORIES 1. A television transmitter actually consists of two separate transmitters. One section uses a camera to scan a scene, and a group of circuits to modulate COUNT 40 an AM carrier wave with the image. The other sec- 4O1MHz FREQUENCY COUNTER tion takes the output from a microphone and uses it to modulate an FM carrier wave. by Telco Hi- Briteness, Highly readable 2. Video information is obtained from the camera as it 7 digit, 7 segment scans a scene with an electron beam, one line at a W' LED readout time. The video signal, with the addition of blanking and synchronizing pulses, is amplified and then Nc direct connection used to modulate the picture carrier wave. This required! (eliminates amplitude -modulated carrier is raised to a specified insertion losses) power level with linear amplifiers and then fed to the antenna. 3. A TV receiver contains many circuits that can be Check your grouped into a few electronic functions. These in- MODEL CT -10 frequency instantly! clude the RF section (front -end), IF section, sound MADE IN U.S.A section, video section, vertical -sync control, hori- ...with the most economical, full feature zontal -sync control, cathode -ray tube, and low- and counter on the market! high -voltage power supplies. Many of the functions ...meet stricter FCC requirements are similar to those found in a radio receiver. COUNT 40 has more features COUNT 10 will display RF carrier frequency 4. The RF amplifier, mixer, and oscillator select the than higher priced counters! of a traumitter ( up to 40MHz) when held desired channel among the many appearing at the COMPACT SIZE. USE FOR near trarsmitter's antenna. No wires to cut, MOBILE OR BASE no plugs or connections required. Has 1 mV antenna and convert the sound and video -carrier Operates on 12VDC or 115VAC input sensitivity and is capable of reading frequencies to appropriate intermediate frequencies. with Optional AC Power Pack Milliwat "walkie- talkies ". Readout display CRYSTAL CONTROLLED TIMEBASE 5. The video section contains circuits to extract the to 10 cycles . Can be loop coupled for service NECESSARY ACCESSORY FOR SSB and aliglment purposes. a NEWEST IC TECHNOLOGY video signal and amplify it to level required for WEIGHT Z LW SIZE 7'i1'W It 4''4. H , 5' deep operating the beam -control portion of the CRT.

Now you can check all 40 with COUNT 40 ! This series is based on material appearing in Vol. 1 of the 5- volume set, BASIC ELECTRICITY /ELECTRONICS, published by ToICO INNOVATORS IN COMMUNICATION ELECTRONICS Howard W. Sams & Co., Inc. @$25.50. For information on the (5161759 -0300 complete set, write the publisher at 4300 West 62nd St., Ind. 46268. "MOULTS COW 44 SEACLIFF AVEGLEN COVE. N.Y. 11542 Indianapolis,

CIRCLE 25 ON READER SERVICE COUPON 104 ELEMENTARY ELECTRONICS /September- October 1977 www.americanradiohistory.com A photo print -timer that does A shortwave station finder/ A solid -state wind -chill factor everything but turn out the lights! marker. Suppose you pick up an meter that can tell you instan- Designed by a darkroom crafts- interesting but elusive station taneously just how cold you feel! man, it features instant reset, in Papeete, Kuwait or Kinshasa. backlighted digit -set dials, This stable wide -band oscillator A compact, portable gas alarm pushbutton stop and start. lets you relocate it any time you for home, trailer, car or boat. like- without hours of searching. It detects many kinds of danger- A battery- operated dickey flasher ous fumes -and could easily -guaranteed to liven up any A nostalgic crystal radio set - save your life! party! Suddenly, your shirt just like the one your grandad buttons start flashing sequen- had. You make it with a Quaker Chi tially! Some people laugh. Others Oats box. MEETS SWL IN GOOF-PROOF just stare. But it's funniest when page 47 they try to ignore you! A futuristic pulse -width modulated mini -audio amplifier. It can boost the volume of a pocket radio to dancing level! Elementary Electronics features YESTERYEAR It's low -cost, practical projects alarm trine. dale, the teat thing! an d !J!$w Quaker Build your own sou ni In Oats boil Osoc9 eae,. options tryst!, radio n simplest the way just like these in every issue! des,pn rot! 9randad did, usug teater,as Im duu,st column called "Ask Hank, He Knows!" a perteel,duplæele. Mail coupon today for your If you have any trouble on a project- complimentary copy! or with anything electrical -just ask Hank. He knows! Yes, every issue of ELEMENTARY ELECTRONICS brings you step -by -step And Kathi Martin, KGK3916, our Citizens instructions, with photos and diagrams, Band Editor. She writes "Kathi's CB for all kinds of devices you'll enjoy building Carousel" -the most entertaining and infor- -and be proud to own! mative CB feature you'll find anywhere! But that's not all. You also get instructive Plus the people who contribute our articles on electronics, CB and shortwave. columns on shortwave, antique radio, Lively columns. Exciting features that make new products, electronics news tid -bits -and much, much more! J ELEMENTARY ELECTRONICS America's son Mich the Mt-ode Yamaha All our writers, editors and columnists J'racócaa 08800 AM ¡rM most absorbing, down -to -earth magazine Antenna Tps Stereo Receiver for the SWL NoteOhepy for the electronics and radio hobbyist. know their stuff backwards and for- affdl nd1- Way -Out Out wards. And they know how to make 1.84 "WY i4Piiti nfrr Invaluable Basic Courses it interesting! With the same kind ELEMENTARY ELECTRONICS in electronic theory! of straightforward language you use P.O. BOX 2630 yourself when For example, you get the fundamental discussing H7I049 training you need to construct your projects electronics or radio. Greenwich, CT 06830 successfully -or lay the groundwork for What's more, they have fun. Which YES! Please send, without cost or obligation, my get-acquainted an electronics career. means you'll have fun, too! copy of ELEMENTARY ELECTRONICS. If I find it is everything you say Each issue presents a Basic Course that it is, bit me for a year's subscription (5 additional SPECIAL INTRODUCTORY helps you master an important aspect of OFFER: issues, for a total of 6 in all) at just $3.98. Just mail this coupon, and we'll send you If I don't wish to subscribe, I will write "Cancel" electricity or electronics. Recent subjects across your bill, return it, and that will end included: Resistors in Combination. a complimentary copy of ELEMENTARY the matter. Either way, the complimentary copy Understanding Transformer Action. ELECTRONICS. is mine to keep. Introduction to Alternating Current. And Send no money now. We'll bill you later Understanding Semiconductors. for a year's subscription -a total of six Name (please print) Our readers tell us these Basic Courses bimonthly issues for $3.98. But if you don't are one of the magazine's most popular and agree the magazine is everything we say it Address valued features. is, simply write "Cancel" across the face of the bill. Send it back to us, keeping the City A magazine with a personality complimentary copy. And you won't owe all its own! a cent. State Zip You'll meet a lot of interesting people in Act today. We're confident that once you the pages of ELEMENTARY ELECTRONICS see your first copy of ELEMENTARY NO-RISK GET -ACQUAINTED COUPON Like Hank Scott, our Workshop Editor. ELECTRONICS, you'll wonder how you did NO MONEY! He conducts a regular letters- from -readers without it for so long! SEND

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CLES FOR MAGAZINES, receive $5 -$10. in mail. 20, Brampton, Ontario, Canada L6V 2K7. FREE CATALOG: Electronic supplies -kits for the BOOKLET TELLS HOW and WHAT to WRITE, 4709 nth. 6% tax. hobbyist. Low prices. Anklam Electronics, WHERE to sell. $2.40 includes postage, AMAZING! $9$ possible mailing letters. Details 6th St.. Wausau, WI 54401. Calif. D. Tupper Gifts, 4011 A. West Ave. "I ", free. Sunrise, 1640 NW 2nd Ave., Pompano Beach, Lancaster, CA 93534. FL 33060. BUILD YOUR OWN TV CAMERA. Great for home and business. Free illustrated catalog. Phone or Broadway FREE! Book catalog sent on request. Cooper Enter- UNLIMITED earnings with fantastic money mak- write: 402 -987 -3771. ATV Research, 13 E. prises, 2108 Yale, St. Louis, MO 63143. ing method. Free details: W. D. McCabe. P.O. Box Dakota City, NB 88731. 68. New London. IA 52645. STOP PAYING EXPENSIVE TV REPAIRS "Do It method. Details FREE Magazine featuring 450 books natural Free details. 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/September- October 1977 106 ELEMENTARY ELECTRONICS www.americanradiohistory.com NEW ...... I. III III ...... III III !. III IN I IN.. I ! !.M...I...I. III ..MOWN PLACE Classified .....MIN .MINN . . MU...... a To be included in the next issue, please send order and remittance to K. S. Wayner, ELEMENTARY ELECTRONICS, 229 Park Avenue South, New York, N.Y. 10003

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ELEMENTARY ELECTRONICS /September- October 1977 107 www.americanradiohistory.com From CIE - Cleveland Institute of Electronics learn by doing! Perform more than 200 exciting experiments with CIE's fascinating ELECTRONICS LABORATORY PROGRAM!

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www.americanradiohistory.com You get your own Experimental Electronics Laboratory... work with components comparable to those used by industry!

With CIE's Experimental Electronics Labora- Testing and troubleshooting are an important Modern space -age components like this IC tory, you'll perform actual experiments and part of your learning experience. Included in (integrated circuit) are professional quality become adept at handling components. This your laboratory is a precision "multimeter" and can be used again and again in many of valuable "hands on" experience helps you to diagnose electrical and electronic troubles your projects. Lesson by lesson, piece by learn the "how" as well as the "why." quickly and accurately. piece your knowledge grows! Prepare now for a rewarding career in Electronics ... the Science of the Seventies. Electronics miracles are changing to- To get an FCC License, you must pass skills and knowledge day's world with breathtaking in demand. Com- speed. a licensing exam administered by the puters and data processing. This growth in electronics Air traffic technology government. And we are confident you control. Medical technology. has generated a need for electronics Pollution can successfully earn your license, if control. Broadcasting and communica- technicians trained in theory and practice you're willing to put forth an effort, be- tions. Once you have the solid technical to build the products, maintain them, and cause the vast majority of CIE students troubleshoot background you need, you can go after them during the Seventies have. In fact, based on continuing sur- the career and beyond. field you want ... work for a veys, close to 4 out of 5 CIE graduates big corporation, Don't just wait for something a small company, or to "hap- passed their FCC exams! even go into business pen" in your present job. for yourself. Get ready now That's why we can offer this Warranty: Yes, Electronics can for a career you'll really enjoy be the door to a ... with when you successfully complete any CIE whole new world of career opportunities the opportunity for a good income and career course which includes FCC Li- for you. And CIE training can be your key. the chance for advancement. cense preparation, you will be able to Send for FREE school Practical experience with experiments pass the Government FCC Examination catalog for the License for which the course pre- Discover the opportunities open to peo- "Hands on" experience helps to rein- ple pared you or you will be entitled to a full with electronics training. Learn how force basic theory. When you learn by CIE doing, you refund of an amount equal to the cash career courses can help you build discover the "how" as well as new skills the price of tuition for CIE's Course No. 3, and knowledge and prepare "why." You'll find out for yourself the you right way "First Class FCC License," in effect at for a meaningful, rewarding career. as well as the wrong way to use We have electronic the time you enrolled. This warranty is courses for the beginner, for the components. How to construct hobbyist, for your own circuits, to good from the date you enroll until the the electronics technician, discover trouble and for the electronics engineer. spots and learn how to fix them. last date allowed for completion of your Whether you are just starting out in CIE offers a number of course. Electronics or laboratory are a college- trained courses where you That's it! We warrant that you will get engineer in need of learn Electronics by updating (or anywhere "doing it yourself." You the License you trained for. in between), CIE work with your has a course own hands designed to fit your back- on electronics components You'll have attractive ground, experience, and lab equipment. This combination and future goals. of job opportunities Send today "head and hands" learning locks There for our FREE school cata- in your have already been many exciting log and complete career information. understanding of the crucial principles developments and breakthroughs For in Elec- your convenience, we will try to have a you'll use on the job in your new career. tronics and some people might assume And representative call to assist in course you do it all at home, in your spare there will be no new frontiers ... no new selection. time, at your best study pace. Mail reply card or coupon to CIE's out- worlds to conquer. Not so. CIE ... or write to (include standing lessons allow you to progress Electronics CIE name and is still growing. In nearly date of this publication), 1776 East step by step. An instructional technique every one 17th of the new and exciting fields St., Cleveland OH 44114. Do it TODAY. time- tested for over 40 years of special- of the Seventies you find electronics ized electronics independent home -study training. I- Importance of an FCC License 41.7L1lct1r1t, Cleveland Institute of Electronics, Inc. and our Warranty CIE 1776 East 17th St'eet, Cleveland, Oho 44114 If you want to work in commercial broad- Approved Accredited Member National Home Study Council casting ... television or AM FM Yes, I want your FREE school catalog and career information or broad- Under package today. casting ... as a broadcast engineer, federal G.I. Bill I am especially interested in: EL -$6 law requires you to have a First Electronics Technology Class Radiotelephone Industrial Electronics License. Or if you FCC License Preparation plan to operate Electronics Engineering or to maintain mobile All CIE career Color TV Maintenance Other two -way communications systems, micro- courses are ap- Mobile Communications wave relay stations or radar and signal- proved for edu- ing devices, a Second Class FCC License cational benefits is required. under the G.I. Print Name Even if you aren't planning a career Bill. If you are a which involves radio transmission of any veteran or in ser- Address Apt. kind, an FCC License is valuable vice now, to have check City as Government certification of certain box for G.I. Bill technical skills. It's a job credential rec- information. State Zip Phone Age ognized by some employers as evidence Check box for G.I. Bill information. that you really know your stuff. Veteran On Active Duty

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