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1. A draze an EV a e o e s Ple Mm Ps NUN ELEMENTARY ELECTRONICS January February 1979 ROJECT BUILDING is supposed to be generally is a challenging and entertaining adventure Yet there are times when it can turn out to be a miserable disappointment all because of a pesky little gremlin known as electronic noise To the electronic en gineer noise is a catch all term that refers to any signal appearing some place where it does not belong Even if you have constructed just a few proj ects chances are that you have been introduced to noise whether you real ized it or not While noise cannot be eradicated completely it can be effec tively minimized once you understand its origins In most instances the key to a noise free project lies in good con struction practice so let s examine some of the techniques used by skilled proj ect builders When dealing with electrical inter ference it is helpful to define two classes of devices noise sources and noise receivers Noise originates at some source and appears in another electronic circuit the receiver Almost anything can be a noise source Some of the more common ones are auto mobile alternators arcing motors the ever present 60 Hz power line high voltage or high current electronic cir cuits and digital logic Similarly al most any electronic circuit can be a receiver although high gain low
2. ane sense of accomplishment that Come ant batiding it your vel Portable It Room Size Electronic Air Cleaner An important addition to any d gt household it UTR removes dust dirt and pollutants from any room in your house while cleaning and refresh ing the air and all for just pennies a day It s especially important for insulated and tightly sealed houses where air can get stale after parties smoking etc Features 3 way cleaning operation to remove both large and small particles and household odors Variable speed control that lets you quick clean a room then lower the speed to maintain a fresh air level Handsome Southern Pecan vinyl finish cabinet blends nicely with any decor Easy NO SOLDER kit assembly too M ORDER Cary Read about these and nearly 400 5 re A other fascinating and practical electronic kits you can build yourself for fun for satisfaction and for savings Mail coupon for your catalog today ag Rd 716 244 5470 White Plains North White Plains 3 4d 10603 7 Reservoir Rd 914 761 7690 OHIO Cincinnati Woodlawn 45215 10133 Springfield Pike 513 771 8850 Cleveland 44129 5444 Pearl Rd 216 292 7553 Columbus 43229 2500 Morse Rd 614 475 7200 Toledo 43615 48 S Byrne Rd 419 537 1887 OKLAHOMA Oklahoma City 73112 2727 Northwest Expressway 405 848 7593 PENNSYLVANIA Phiiadelphia 19149 6318 Rcosevelt Blvd 215
3. k uL E t 19 i Lir 24 s po X Ww c 3 4 E E takes a look at of the simplest and yet most useful electronic devices in the hobbyist s inventory the transformer In these days of hyper fast electronic evolution the transformer has remained basically unchanged for the past fifty years and we will prob ably be still using them fifty years from now Understanding how they work is easy if you just read through this Basic Course This series is based on material appearing in Vol 2 of the 5 volume set BASIC ELECTRICITY ELECTRONICS pubiished by Howard W Sams amp Co Inc 25 50 For information on the complete set write the publisher at 4300 West 62nd St Indianapolis Ind 36268 UNDERSTANDING TRANSFORMERS W hat You Will Learn To understand how two common electrical devices work You will learn how a transformer transfers power from one winding to another You will learn how to cal culate the change in voltage current and imped ance produced by a transformer with a known turns ratio and how to select the proper turns ratio to produce a particular change You will also learn how a magnetic amplifier controls a large AC cur rent with a smaller DC current WHAT IS A TRANSFORMER A transformer is a device for changing the voltage of AC electricity Transformers work on the principle of induction Basically a transformer has two windings a primary and a secondary w
4. LOC Y Introductory Course page79 e S DO E eS Rall __ Make your own odds GD our LLI sports program U MICROCOMPUTER PROJECTS Make computer music page 29 Match wits witha microprocessor page 53 Count like a computer page 61 R 20Ts Super DX ANYdd IHY 80 NANSHLYY ONTONY Ig 5 i OU io Happiness cks out TES HOO progr ammabi FAN mo T89b40 by Cacnurive cer Information Unlimited EE Eoo Mutt Minder T WT es q e HE moms Four new 8 hot CBs E 1486 0 Hoof your way throug EL computer logic with 2342 Rhythm amp Elues Box 4 DAVES PUBLICATION FOR THOSE OF YOU WHO ARE HAVING SECOND THOUGHTS ABOUT YOUR FIRST CB Move up to the all new Cobra So if you re having second 29GTL It s the third generation of thoughts about your first CB make the trucker proven Cobra 29 your next CB the Cobra 29GTL like the 29 and the 29 XL before We back it with a guaranteed it it advances the state of the art warranty and a nationwide network Transmitter circuitry has been of Authorized Service Centers refined and updated to improve where factory trained technicians performance are available to help you with Heceiver circuits have been installation service and advice redesigned to include dual FET But more important than that mixers a
5. 6 2N2369 TRANSISTORS NPN switch like 282222 1992 1 00 12 1 01 3 8 AMP 50 PIV TRIAC TO S metal 5403 1 00 tor 1 01 D 2000 FACTORY REJECT DIODE zeners rect signal untested 2 5369 200 4000 tor 2 01 40 AXIAL ELECTROS aast d valuse amp capscitance 4 Shans nim dh 2 00 60 for 2 01 D 40 UPRIGHT ELECTROS seet d vaiuas capacitance 3229 2 00 80 fer 2 01 D 150 RED DISC SPECIAL Eris mostiy marked pop values arnev bec 2 00 300 fer 2 01 C 10 15 VOLT ZEMERS 400 mw gisss axial s 404 1 00 20 fer 1 01 BULLET RECTIFIERS Order by Cat No 60864 and vottage o m FULL WAVE BRIDGE RECTIFIERS 10 A PRY Sale Ztor O 400 199 M Order by Cat No O 50 1 29 1 30 O 600 225 226 2447 amp vetage 100 DON 1000 250 251 INFLATION PARTS amp SEMI ONE CENTERS 100 CAPACITOR SPECIAL disce myter lytics more 2738 E ae 10 VOLTAGE REGULATORS hobby LM 320 340 TO 3 ovs Mam ts t Pe 2 00 30 PANEL SWITCHES slides rotaries mod etc renis d ous 2 00 200 RESISTOR SPECIAL to 1W carbon metal v oh grate rt e nrbe 2 00 200 HALF WATTERS rsslators carbon metal Wu ee 2 00 100 NATIOWXAL IC BONANZA lineare 74005 ROMS 2860 Vo Ws 2 00
6. Br as a ere rhi rd far uv wee ie AU N i Mera espendahi ya PER 118 Kowd Serial 11 geaka Bewar I eaout vla ok SERI Rear MOM and 28 A BAM Fahy lntirinced wiih CRT ov am MES naet wis men uei xvi tut uius eut 9909 LESS 0 wan vm Nea N e Be mr E arit WWE rare Ke kad Sy Wn te ha me me imn d 1 8 1 1 _ MOLEX I C SOCKET PINS N 70 5 50 50 PROCESSORS __ ze YUE 4235 i PRE CY DOUBLE DIGIT DISCOUNTS SAVE YOU EVEN MORE HANDLING raar VOLUME CHARGES anrr ee DISCOUNT M 0 00 5 24 99 au MB atu a POM S 000 4 99 Add 7 08 gt tel 5 005249 44 50 75 25 005 9 99 lam 10 19 000 Add 50 50 7 ow 100 00 499 99 Lans HSN SO Add 0 25 ag T X Lan 70 100 00 amp i 1000 00 amp Up Lets 23 ac 2 MICR 32 gt 2 3 isi ugyon E DIODES i 30719 17 M B 1 f Y Y ST 141 ID CORPORATION E 44 ES a Oe w r t 2799224224 m ERL ZL R 333 C w DT ra 0 10 139 7170 HD 19 00 Fatt lt Quality Electronic Components iver Fats May 54701 m 9 0 Be
7. New bicycle lamp helps lower the frequency of hurts O ANY DRIVER WHO has ever come upon a cyclist who s bicycle has poor lights at night knows how really hard they are to see What seems bright and easy to notice to a bike rider is almost in visible at 100 feet In fact in a high per 72 by Elizabeth Fox centage of accidents where a bicycle is hit by a car at night the driver often says that they never even saw the cyclist or saw them only when it was too late A Boulder Colorado firm has come up with a device that they hope will re duce the hazards of nighttime cycling by making the bicycle highly visible from all directions The Laser Lite as it is called it has nothing to do with lasers is a fluorescent tube powered by a small wheel mounted generator The unit emits a bright green light that is easily visible for more than a quarter mile and can usually be seen more than a half mile away Green Lantern The light begins to glow at 2 mph and because of its construction it remains uniformly bright over the total speed range This color of green was selected because it has been shown that it is the most visible color in the spectrum The unit is reported to be durable weather resistant and to last for about 3 000 hours of use The entire system weighs only 19 ounces The Laser Lite retails for 14 and is manufactured by Life Lite Safety Products Inc 1140 Pearl Street Boulder CO 80
8. Today s Breadboard The CSC Model DM 1 Design Mate pro vides the three elements most basic to electronic circuit investigations a power supply breadboarding area and meter in one convenient package for only 69 95 The meter measures O to 15 VDC 5 accuracy and is independent of ELEMENTARY ELECTRONICS January February 1979 CIRCLE 62 ON Quo X rar udi we a iara HN L ae in Ns E ms HA E m ao M wr aN the power supply with leads brought out to a pair of five way binding posts Thus the meter can be used to set the adjustable power supply s voltage then to monitor circuit action The built in power supply is adjustable from 5 to 15 VDC output at up to 600 milliamps with better than 1 load and line regula tion and less than 20 mV ripple and READER SERVICE COUPON noise at full load The solderless bread boarding area is configured from CSC QT series Quick Test socket and bus strip elements It provides enough area to comfortably breadboard a circuit with 6 DIP ICs plus associated components The DM 1 requires only 12 watts or less at 117 VAC 60 Hz For additional infor mation contact Continental Specialties Corp 70 Fulton Terrace New Haven CT 06509 VOM Workhorse A new battery operated VOM from Leader reads as low as 0 25 Volt and 50 micro Amps full scale The Mode LT 70B Volt Ohm Meter is protected against overload and polarity reversal
9. 29 69 1 49 2 tor T 80 50 46 A6 30 20 1 50 30 1 50 120 1 80 1 50 1 50 1 50 1 50 1 50 1 50 1 50 1 50 1 50 1 50 1 50 ono 00000000000000 000 000 PENNIES FOR YOUR MEMORIES Type Description 1103 1K Dynamic RAM 5202 2K Prom 3 5262 2K x i Dynamic RAM 1702A 256 x 8 EPROM o MM5280 4K x 1 Dynemic RAM gt mua CAE order DY M and conduc 1 Sale d Sete s t 1 99 Cond 196 1 99 6 4 8 ett QE RR 0 yee LM340T 18 LM386N LM531H LM532N LM532H NE540H LMSS5V _ 556 LM558V LMSS8H LM561N LM565N LMS65H LM566 LM567 LM703N LM704H Each 1 49 1 49 49 KKK 944373 25 5 95 1 79 39 39 METTI 3423838 Sate ic Sale 1 29 1 36 2 95 2 96 99 1 00 4 95 4 96 3 95 3 86 Removed trom new tested equipment ZENERS by cat 5210A amp voltage amp wattage 1 Watt Sale 7 8 5 for 1 D amp 2V 5 for 9 1V 5 for 10 V S tor O 11 V 5 for 12 v tor O 45v 5 tor COPYRIGHT 1978 POLY PAKS INC Pub Wa dub m x T FO 220 Power Tab V Mini dip 10 3 1 2 fo 1 50 1 50 50 30 226 1 40 Order by Cat Mo 3459 amp Type No 1 SALE 10 tor 1 01 10 tor 1 01 10 fer 1 01 10 fet 1 01 10 for 1 01 10 for 1 01 10 tor 1 01 Type Mo 5N74184 c 874155 79 80 74156 39 49 D N74157 99 1 00 N74158 99 1 00 N74181 1 25 1 26 D N74161 1 39 1 40 D N7
10. Electronic Music Products cffects devices to computer controlled modular synthe sizers Select from experimenter s kits step by step product kits or fully assembled Eel equipment sf Extr Re W p di T J a n yas one 4 T 1 TE TOR es 28 C d S E wa VOTER ud imn m E 1 HAMA ELECTRONICS INC 1020 W Wilshire Blvd OklahomaCity OK 73116 SEND FREE CATALOG TO name address city State Zip__ HAA ELECTRONICS DEPT EE 1020 W WILSHIRE BLVD OKLAHOMA CITY OK 73116 URB NE CA us Um NP AN GR Gm GR NE AN GN Gm Gm Gm Gm Om Gm Gm em Guy SES x wa ms UP SONS UD UP UD ND UE NDS GA GR Gm GR Gm Gm Gm Gm AW AN UB UA W aw X CIRCLE 15 ON READER SERVICE COUPON 16 PORTS Hr FI REPOR 1 S prf k PORTS Hi 3 UM REPC REPOF 2 Hi Fi REPORTS Hl FI REPORTS HF i REPOR FI REPORTS HF REPORTS REPORT HIFI REPORTS REPORTS Hi Fi REPORTS HIFI REPORTS REPORTS H FI REPORTS H HiFi REPOR PORTS H F I REPORTS i Ci DQEDORT POR TS HI FI REPORTS HI FI REP gu Hi FI REPORTS HERP TS HI FI REPORTS ut FX OTC 31 V 7 Give your e the cassette advantage with Sanyo s budget priced RD 5350 or Pioneer s microprocessor controlled CT F 900 By
11. Input sensitivity 0 4 aV Adjacent channel rejection 50 dB AGC action e e 4 dB Transmitter Section Test AM RF output 3 2 watts Modulation to 85 NELEMENTARY ELECTRONICS January February 1979 v a e COBRA 142 GTL e MOTOROLA ELECTROSCAN CR 520 PRESIDENT VEEP e REALISTIC 470 Relative sensitivity for 85 HIDU T 29 dB Modulation limited to 100 yes Editorial Remarks The CR 520 has double conversion jack for remote speaker L E D digital channel dis play on microphone and memory which remembers the channel last used or tunes channel 9 when the transceiver is turned on L PRESIDENT VEEP 99 95 President Electronics Inc General Description A 40 channel AM transceiver for mobile and P A operation Power supply is 12 to 13 8 VDC with negative or positive ground Overall dimensions are 1 9 16 in H x 5 7 16 in W x 7 15 16 in D There are front panel controls for channel selection vol ume squelch Switches for PA on off ANL Standard accessories in clude a microphone mobile mount DC power cable Receiver Section Test Input sensitivity 0 4 aV Adjacent channel rejection 69 dB AGC action 13 dB Input level for S9 meter indication s 150 aV CIRCLE 104 ON READER SERVICE COUPON Transmitter Section Test AM RF output 4 0 watts Modu
12. The mint made o mistoke but we didn t i 1 Now is your chonce to toke odvontoge of their mistake 1 5 25 yeors 1 1968 5 Penny vex L 1 1960 D Smeal Date 1955 5 Poormon s Double Die OR 6 95 BUYS EVERYTHING IN BOTH OF THE ABOVE SPECIALS With Every OHer you Receive Add 5 25 tor Postage Bl More Free Coins w Or Free Brochures JIM De NINNO amp CO Suite 5 Pike Bldg Viewmont Village Scranton 18508 717 961 0203 CIRCLE 36 ON READER SERVICE COUPON shen Seve La R NEWEST EDITION ONE STOP SHOPPING FOR 5 WL S le RECEIVERS special OX mods ANTENNAS e PRESELECTORS e TUNERS e CALIBRATORS e CLOCKS e HEADPHONES e BOOKS LOGS GILFER SHORTWAVE Dept EE 1 Box 239 Park Ridge NJ 07656 BE A You ll enjoy your work as 3 Lociamith because it is more fascinating than a hobby and highly paid besides You ll go on enjoying the fascinating work year after year in good times bad because you ll be the man in demand in an evergrowing field offering big pay jobs big profits as your own boss Train at Home Earn Extra Right Away Send for FREE booktet today LOCKSMITHING INSTITUTE Div Technical Home Study Schools Dept 1472 019 Little Falls N J 07424 Was never so thused and de lighted with lessons in my entlre life grossed over 3 000 in one year just working weekends Rock
13. formance antenna fits any 24 nection Chrome plated ferrule with antenna including the Heliwhip No 24 thread Clamps to 1 pipe new mount or cable is needed with Model 12 this adaptor Model 1 i Top loaded CB antenna with CLASS Anixter Mark s new standard of excellence Combines Quick On Connect Chrome plated connector for rapid CE el el apa sturdy heliwhip fiberglass construction inni wilh 36954 Na with a heavy brass chrome plated mast YG hedhin oda QOC Height 54 Tuning Range 26 9 27 5 MHz Model AAC 11 4 re THE GREAT GRIPPER gives you a totally designed package Mark V Base Station Antenna ETE HEH The Mark V is a full 20 ft tall It is Super powerful ceramic magnets extremely sturdy and designed for New antenna cesign to complement heavy duty commercial use Lowest the mount VSWR over the greatest bandwidth A full 18 feet of cable Supplied with universal mast mount Fiberglass and top loaded THE GREAT ing kit mounts on any pipe with GRIPPER antenna looks sleek and slim O D from 1 to 1 Model MK V in black and chrome And it s a 40 chan nel antenna with an average VSWR of 1 4 1 over all 40 channels Model MAR 11 S3 60A ANIXTER MARK Manufacturers of a Full Line of Point To Point Antennas Microwave Two Way e Amateur CB 5439 W Fargo Skokie IL 60076 312 675 1500 Ma
14. 15 LM340T VOLTAGE REGULATORS 5 to 24V TO 220 263 2 00 100 POLY STYRENE CAPS sest d values voltage hi Q 27291 2 00 SO THERMISTORS resistors that change with temp 400 2 00 20 BRIOGES untested 2 4 6 amp full wave 4022 2 00 25 LAMP N SOCKET SETS micro 1 8V T2 39 7 2 00 15 MIXED READOUTS hobby untested 127 3 etc 2 Rre ee 2 00 150 QUARTER WATTERS resistors metel Him marked 3413 2 00 100 PLASTIC TRANSISTORS unteated 70 62 2604 fui em SS 200 200 PREFORMED RESISTORS 4 1W marked asst 2608 2 00 200 PRECISION RESISTORS 4 1W 1X 2X merhed 2428 2 00 60 DIPPED MYLARS shiny flniah asst d values 2887 Pu 2 00 30 VOLUME CONTROLS audio linear asat d values 2029 cry E A T ar 2 00 30 CLOCK CHIPS Nattonal hobby amp untested alarm SO080l 2 00 30 MM5262 2K RAMS hobby untested 3940 2 00 10 PUSM SWITCHES push to brsak spat alarma Y 289 AE gt 2 00 25 0 4000 SERIES CMOS untasted SOX useable yield Lv 5284 2 00 i CHARACTER GENERATOR 5 7 Mostek MK 2002P 3898 4 95 1 CONDENSER MIKES sensitive 500 ohms 1 5 Volte csi vides ed stores 1 4 95
15. By August of 1980 the sunspot cycle will be headed back down eventually reaching a minimum sometime in the middle to late 1980 s So enjoy or en dure the conditions of this sunspot peak while you can 7 87 BNEE Continued from page 66 or a set of paddles one for dits and one for dahs with separate electron ics or a bug is pretty much up to you and what you feel most comfort able in using If you elect to go with an elec tronic keyer make sure the output of the keyer is compatible with the key ing circuit of the transmitter Read the manuals carefully An improper con nection or too much voltage on the switching transistor in the keyer s elec tronics will lead to an early repair job and some warranties don t cover owner abuse What do I use A straight key but one of these days I ll get around to working with an electronic keyer In Closing Next time we ll talk about sending and receiving code and review some basic operating practices In advance of this discussion you may wish to order some supplemental mate rial The American Radio Relay League 225 Main St Newington CT 06111 wil supply the following operating aids free of charge 1 CD 5 9 WI1AW Schedule 2 CD 139 Current On the Air Code Practice Stations 3 CD 220 The R S T System Time Con version and 4 CD 218 Amateur Message Form Also ask for an order blank for the ARRL Logbook Although the Operating Aids ar
16. Power for all the above is provided by a regulated power supply of con ventional design consisting of TI Cl and ICI R5 C3 C5 and R23 C8 isolate the power lines to IC2 and to the output section from the rest of the circuit to prevent undesirable interactions Getting It Together Although it in volves a fair amount of wiring there is nothing particularly difficult about as sembling the Rhythm amp Blues Box Follow the directions given here and the diagrams and photos and you shouldn t have any trouble If this is one of your first projects enlist the help of someone experienced in electronic construction When assembling the rhythm syn thesizer keep in mind that CMOS IC s IC3 through IC11 can be damaged by static electricity or other excessive voltages so handle them appropriately 31 a a RHYTHM amp BLUES Leave them in their packages until the final steps of construction as described later Although the R amp B Box could be hand wired a printed circuit PC board will make the job easier and the finished product neater An actual size PC etching guide is provided Most of the components of the synthesizer mount on the PC board as shown in the parts placement diagram Note that ten jumper wires are required identi fied by J These are all inserted from the component side of the board and may be bare wire Use sockets for the nine CMOS IC s using a socket for IC2 is optional Heat sin
17. TOIM DO IL Designed N 4 A be ruhet Hush mounted ned o plate for the rfe louz ap o e 3 5 8732 3 15 7 Tall z e et reflection mhle ts bL 4 D lt 2 1 8 Deep a GLARE B1aCK NCLOSUEIL WITN 270 Swivii BNACRIT M 24 ode of ABS cinite md deu e Quick and tos To Install 70 7 TANG uma agang he josh or d e Port No 5001K v eher 5 e v ove the y IOS bel ret be f ip 8 h ond dd tior leugeed to t the mos SASRISRANNIAINSO ET t ra Be ie misa R ccc s i 3 t vetting 0 1 PUTM BUTTON WITCMAS 7 nutes nd treat on off The X a C dolar d 8858 Faesaneed A SIT OF 1457 TO FOLLOW MSTRUCTIONS To guide tep br Mounting howdwore ine iudei MA1003 Clock Module and Switches only 401 Bezel and Enclosure only 5 001K Digi Clock Kit incites 41003 ond 401 LELIA TTET gt I Bake FIT TFF TFF TT T TT T T TL ai gu eusts 52925 92 teers au EES E dH 159 3 Seat RZ ET 35 L ERSSESRASRUGJOGUUUULZIIAGgEMREXNNMRHASESSLIETHS z2 12582885 73 Ar iat ardant ch nm 4 uc 108 B w RU ue OA Ea T da bas 23 4 104 ACID a o e w m 4 AN 1 L nui T 2 p rS S n 5 oom DR 1M 00 L Lu
18. current loops may be completely iso lated However points A and B could be connected with no change in the induced noise voltage Therefore as was the case with the electric field we must consider coupling between stages of the same device or between stages of two separate devices Let s examine the factors that cause increased noise coupling 1 an in crease in the magnitude of I 2 a decrease in the separation of the two Loops 3 an increase in the frequency of 11 4 orienting the loops so that their planes are parallel and 5 an increase in the area of the receiver loop From the above several methods of noise reduction are suggested First separate the two loops in particular keep high current stages away from low level stages Second minimize receiver loop area This applies espe cially to the wiring associated with a receiver stage All wires to a jack a switch or a potentiometer should be twisted together thus minimizing pick up loop area Third try to minimize the source loop s magnetc field This is F L Hd CIRCUITRY HIGH CURRENT 35 most conveniently done by using twisted wired again To see why this is effec tive imagine taking the source loop stretching it then twisting tha wires together The currents in the twisted pair flow in opposite directions and because twisting keeps the two wires in close proximity the magnetc field of one wire cancels that of the other Even better than
19. es pecially carefully selected information has been obtained from a data base we can read it and make our own de cisions about it or we can subject it to further analysis on the individual com puter The forms this will take in the future will be as varied as peoples teh AAEE th ick H SCOTT POWER TRANSFORMERS STEP UP STEP DOWN ISOLATION TRANSFORMER Hard to find alep up or down isolation transformer lt will take either 208 or 230 volts and give an output of 115 volts or it will take an input of 115 volts and give an output of either 208 or 230 volts Rating 00 VA CRAMER catalog shows a STANCOR with 500 VA rating for 94 19 Wt 23 Ibs O 6892S FERRO RESONANT TRANSFORMER 12V 4 amp winding amp 26V CT 15A For building computers leb power supplies battery chargers Brand new designed for huffs with 6 mid capacitor Wt 25 lhe DELTA has the entire surplus inventory of SCOTT agora that LA v in their various amplifiers amp receivers SCOTT was famous for the quality of their equipment and nowhere 18 it better shown than in these transformers Almust all havea 0 6835S 24 95 24 50 2 for 47 ca netic shield for hum x a eqe eise e needs and interests But with the ability are conservative E 50 0 50 MICRO DC Second 2 gcc al AR to access large bodies of information DEL
20. on future sunspot activity which will affect radio propagation Denis Casey supervisor of the Canadian Broadcast ing Corp monitoring station discussed his division s activities A busload of convention goers who stayed for the fourth day of the ANARC convention traveled from Montreal to Ottawa to view the monitoring station s activities firsthand For more information about the As sociation of North American Radio Clubs and its numerous affiliated clubs and data on what these clubs offer to SWLs and listening fans simply drop a line to Dave Brown Executive Secre tary of ANARC 557 Madison Avenue Pasadena CA 91101 Since ANARC is a non profit organization please in clude a self addressed envelope busi ness size with 156 postage affixed What s New As many listeners know it is possible to hear some of your favorite programs of various shortwave stations without even listen ing to shortwave Yes particularly the PBS stations in the United States air off the air relays of such programs as the British Broadcasting Corporation s Radio Newsreel and various program transcriptions from stations such as Radio Nederland Many readers are using the Yaesu FRG 7 receiver or tha same radio with its own house brand name the Sears shortwave receiver Now the Japanese manufacturer has come out with a big brother to the popular FRG 7 which SWLs have dubbed the Frog Seven The new receiver is the Yaesu FRG 7000 and
21. vD E K Sr ie 7 16 x J 6 SWITCHES ON A DIP 3671 1 29 1 30 Cat 3178 lo SSWITCHESONADIP 160 260 2 61 ng Order By Cat Mo 1 amp Type No SN7400 N7401 N7403 N7404 N7405 N740 N7410 5 7416 N7420 N7421 N7423 947426 N7430 507437 N7438 N7440 N7443 amp K7544 57446 N7450 N7451 5 7453 07454 N7455 N7460 N7444 N7465 N7470 ooosnnaaagonpngpogagagaaaaaoabgeaaago TTL S AT CENT CIBLE Each 2 For 19 4 20 49 20 25 26 19 20 19 20 19 20 28 26 38 36 32 33 48 50 29 39 19 20 29 30 19 20 25 26 19 20 59 60 19 20 1 25 1 26 19 20 18 20 19 20 29 30 19 20 35 36 19 20 19 20 19 20 Type No 47471 N7472 N7474 87475 47480 N7482 N7483 47406 57488 47489 5 7490 547491 N7492 997493 547484 507495 507496 N7498 5774107 9474113 5074114 9474121 50746123 5074126 N74136 5N74140 N74145 N74153 DponDaoooanaaggaagooooongaoaaaoagog Each 12 5 6 1 28 1 30 POP AMPS AT CENT CIBLE PRICES Case code Type No C LM300H C LM300N LM301V C LM301H O LM308V O LM308H LM309K O LM311V O LM320T 6 CO LM322N C LM339N O LM340K 5 O LM340K 6 O LM340K 8 O LM340K 12 O LM340K 15 O LM340K 18 D LM340K 24 O LM340T 5 O LM340T 6 O LM340T 12 O LM340T 15 Each 79 49 4S 45
22. 150 GLASS ZENERS 400 MW untested better than SOX yleld s 2740 209 75 CARBOFILM RESISTORS 4 watt 5 amp 10 merkad ssst s 3534 2 00 250 UNMARKED CAPACITORS polystyrers molded pop values 3805 2 00 300 SILICON SIGNAL DIODES micro Eliass reners tool SOX yleid 2628 K 2 90 8 1 SOCKETE 14 18 pin solder tall Lv 3621 2 00 100 1N4148 914 SWITCHING DIODES 501 yield Untested 2418 eo SE EE 2 00 30 PC TRIM POTENTIOMETERS thumbwheel screwdriver ass t x 3345 2 00 15 SLIDE VOLUME CONTROLS asst d values duals singles x 308T 2 00 75 4 CABLE HES plastic liike Ty wrap 218 2 00 10 CRYSTALS may include CB Ham mora 3250 2 00 100 TERMINAL STRIPS trom 2 lugs up 313 ism CURL IS Saeed v 2 00 30 NE 2NEON LAMPS ell 200 good 2 13 See VO 200 40 ft SHIELDED CABLE 1 cond mikes phonos ISTI heeii M eek 200 1 3 SOUND TRIGGERS sound triggers scr w amp 2 362 2 00 ji 10 CB CRYSTALS for Phase lock 1000 HAM HC 19 2 S050 sae pa 1 Hen pi seas 2400 Your Choice wie for wo 96 PARTS Thei LOSE Faetory dumps ALONE his production Jine rejects and 00000000000000900000000000 10 AMP POW 1N4000 Epoxy Rectifiers Order by Cat No and Cat No Type Vol
23. 288 0180 Frazer Chester Co 19355 630 Lancaster Pike Rt 30 215 647 5555 Pittsburgh 15235 3482 Wm Penn Hwy 412 824 3564 RHODE ISLAND Providence Warwick 02886 558 Greenwich Ave 401 738 5150 TEXAS Dallas 75201 2715 Ross Ave 214 826 4053 f Houston 77027 3705 Westheimer 713 623 2090 San Antonio 78216 7111 Blanco Road 512 341 8876 UTAH Salt Lake City Midvale 84047 58 East 7200 South Opening Mid November VIRGINIA Alexandria 22303 6201 Richmond Hwy 703 765 5515 Norfolk Virginia Beach 23455 1055 Independence Blvd 804 460 0997 WASHINGTON Seattle 98109 505 8th Ave N 206 682 2172 4 WISCONSIN Milwaukee 53216 5215 W Fond du Lac 414 873 8250 HEATH ues This FREE Catalog coupon can also be rsdeamed at any of the Electronic Centers nationwide See IIst at left HEATH 5 Heath Company Dept 139 490 LU Benton Harbor Michigan 49022 Please send me my FREE Heathkit Catalog am not on your mailing list NaI mt Address 2 E Wu City s G 28 5 eis t n a n ma GX 359 Zip a CCS eco i CIRCLE 1 ON READER SERVICE COUPON Ranra em INDY CATOR Dual function Digital Tachometer CIRCLE 53 ON READER SERVICE COUPON This super RPMs counter is a digital winner on any
24. 62nd St 317 257 4321 KANSAS Kansas City Mission 66202 5960 Lamar Ave 913 362 4486 502 245 7811 LOUISIANA New Orleans Kenner 70062 1900 Veterans Memorial Hwy 504 722 6321 MARYLAND Baltimore 21234 13 E Joppa Rd 301 661 4446 Rockville 20852 5542 Nicholson Lane 301 881 5420 MASSACHUSETTS Boston Peabody 01960 242 Andover St 617 531 9330 Boston Wellesley 02181 165 Worcester Ave Rt 9 just west of Rt 128 617 237 1510 MICHIGAN Detroit 48219 18645 W Eight Mile Rd 313 535 6480 E Detroit 48021 18149 E Eight Mile Rd 313 772 0416 MINNESOTA Minneapolis Hopkins 55343 101 Shady Oak Rd 612 938 6371 St Paul 55106 1645 White Bear Ave 612 778 1211 MISSOURI St Lou s Bridgeton 63044 3794 McKelvey Rd 314 291 1850 NEBRASKA Omaha 68134 9207 Maple St 402 391 2071 NEW JERSEY Fair Lawn 07410 35 07 Broadway Rte 4 201 791 6935 Ocean 07712 1013 State Hwy 35 201 775 1231 NEW YORK Buffalo Amherst 14226 3476 Sheridan Dr 716 835 3090 Jericho Long Island 11753 15 Jericho Turnpike 516 334 8181 Rochester 14623 937 Jefferson f pee m o gt SOLU VEY MA GLS LL COLI y DAG LL ULLA A gift is a teu y satictyng way to celebrate ihe holiday season in add ngn to giving 1 ee of rlectromc equipment that will perform deautitully tor ears 10 come yov give Me
25. 7415244 1 95 7415347 1 25 74LS669 90 74LS30 15 a 7405162 84 7415245 1 95 74 5348 I 74LS670 2 00 74LS32 25 74LS B4 7415247 1 25 4 1 533 27 1415109 32 epe 89 745248 1 25 7415353 1 35 AI new major manufacturer prod 74LS37 23 745112 32 745165 125 745249 1 25 7415362 7 00 uction material offered 744538 23 745113 39 7415166 1 45 741525 85 7415365 55 Largest variety of device types 74LS40 19 74LS114 39 7415168 150 745253 85 7415366 55 available anywhere 74LS42 54 74LS122 50 7415169 150 74019257 60 7405367 55 y s UV EPROM MOS Static RAM S MICROPROCESSOR Stock level Part No Price CHIPS Stock level Part No Price 7300 2708 7 99 i j CPU s 41400 21 14 7 50 Stock level Part No Price 6800 TMS 2716 24 95 T AE 21600 8080A 295 5 50 3 power supply version 16K pin for pin plug in 59500 2102LFPC 1 19 2700 6800 8 95 7 95 replacement for 2708 1K 350NS Low Power GENERAL MOS Dynamic RAM S INTERFACE INSTRUMENT ete Sl an SUPPORT CIRCUITS 1 Amp Rectifiers Epoxy TARE eee otock level Part No Price Stock level Part No Price epe D as 2110 4 4060 3 95 1250 8212 198 9Miton 1N4002 100V 03 57000 300NS 1800 8214 x35 395 5 M l on 1N4003 200v 045 390000 VGN 5 7 Million 1N4004 400V 049 80000 WOBM 1 6 Million 1N4005 600V 055 7000 8 Milion 1Na4006 800V 065 1 8 Milion 1044007 1000 07 27550 16K 416 3 11 95 11200 8216 1 98 1700 8224 2 75 18660 16K 416 5 8 95 2800
26. Bend the stop out of the way to allow all twelve positions to be indexed Note that in the newly created position the switch rotor does not con tact any of the stationary treminals this position is used as the off position When wiring switch S3 and pots R11 through R22 take care to connect the wires in the correct order Note that S3 is wired only to stages 2 through 12 of the shift register The chassis panel and cabinet were custom made for the author s unit but standard commercial items could be used The author s cab inet measures 4 in high by 10 in wide by 5 in deep Tuning Up After you have com pleted the wiring and assembly but be fore you insert the CMOS IC s check out the power supply Plug the unit in switch it on and measure the voltage between the point labeled P and either one of the points labeled G on the PC board It should be 10 volts plus or minus 0 1 volt with P positive If not check the power supply S1 Tl RECTI Cl for wiring errors or faulty parts When the power supply 10 0 PIN 7 OF IC5 6 7 oe lo o L IN 2 10 5 9 OF IC8 9 10 PULSES TO SPEAKER PULSES TO LED I amp ONE COMPLETE a SEQUENCE Need an adjustable waveform generator The Rhythm and Blues Box can handle that too Simply tap in at the appropriate point hook up your scope and you re ready to go 32 checks out unplug the R amp B Box and insert the IC s observing their ori
27. Box E Menlo Park Cali fornia 94025 is the book we drew our sample program and flowchart from Its a large oversize volume which re tails for 8 00 and contains the listings to forty eight games along with sample runs and hints as to playing strategies About twenty five or more of the games wil run in a system with 4K free RAM What To Do s table of contents di vides the game programs into ten dif ferent categories everything from num ber guessing games to truly sophisti cated science fiction programs requiring more than 20K of memory This is a book which has become a classic in a new field and most com puter stores stock it When it was origi nally published a great many hobby ists were time share users If you own a microcomputer you may have to change things around to fit your Basic and some of the programs will likely be too lengthy to load without cutting modifications Creative Computing Magazine has just released Basic Computer Games Microcomputer Edition by David H Ahl Creative Computing Press P O Box 789 M Morristown N J 07960 8 50 The book enjoyed a previous incarnation under the title 707 Basic Computer Games Originally the pro grams were written in different dialects of Basic and the print quality of the listings was to put it very mildly rough on the eyeballs The games 102 this time are al most all capable of being run in 4K if you don t mind cutting off the instruc tions
28. College Avenue Indianapolis Indiana 46220 JAPANESE Girls Make Wonderful Wives We have riage Only 1 00 brings application photos names descriptions Qeustionaire Etc Japan International Box 156 AA Carnelian Bay CA 95711 SURPRISE send 254 to Langen Box 181 DC Downsview Ontario A Card Players Dream 254 to Langen Box 191 DB Downsview Ontario M3M 3A3 BEAUTIFUL Mexican Oriental girls Needing Amer ican SBoy Friends Free Details actual photos World Box 3876 DC San Diego CA 92103 DATE WITH DIGNITY Professional Matching Drawer 6765 Fort Worth 76115 817 921 0281 MEET SEXY SWINGERS Nationwide FREE De E E Age Gateway Box 338 DC Lafayette FREE 1 000 LADIES PHOTOS World s largest Matrimonial Catalog Postage Handling 1 00 Inter contact Box 12 Toronto Canada 2M8 MORE g For Greater Advertising Savings Results and Profits Place your ad in one at our SPECIAL COMBINATIONS Combo 1 Combo 2 or Combo 3 Each combination is designed to give your ad the largest audience available For further information write to R S Wayner Classified Ad Manager Davis Publicatons Ine 380 Cexington Ave N Y N Y 10017 Classified Continued PERSONAL Cont d BECOME ORDAINED MINISTER legally Creden tials free Use title Reverend Write Church the God Within Box 01 5313 Miami Florida 33101 2 BEAUTIFUL ME
29. Continued from page 42 shops in larger cities carry this wire in stock for use in rewiring antique table or floor lamps otherwise use a brown plastic linecord unless the radio cabinet is white in which case a white line cord looks best Next check all the tubes if you have access to a tube checker otherwise check the filaments with an ohmmeter Wash them carefully and put them back into the proper sockets Connect a 100 watt lamp in series with the radio and wall outlet see circuit and plug in the radio Why do I recom mend this step Simply because the set may have a short in it if so the lamp will burn brightly and you will not burn up a power transformer or other part If the light bulb does burn bright ly pull the rectifier tube if the set has a power transformer and if the lamp doesn t dim the transformer is prob ably shorted or a filter capacitor is shorted If the light bulb burns dimly then you can plug the radio line cord directly into the wall outlet Filter Caps Listen for hum in the speaker a barely audible hum is good a loud hum like a buzz saw is bad if you have a loud hum replace the filter capacitors They will either be in a round aluminum or cardboard tube about 1 inch in diameter and 3 inches 86 HIGH CURRENT CIRCUITRY i L long with a red blue and black wire coming out the end mounted under the chassis or an aluminum or copper can about 1 inches in diameter and 4 inches l
30. IC chip are mounted on the other side Be careful to keep the foil side component bodies off the metal surface to avoid shorts Be especially careful with resis tors R4 and R5 and capacitor C3 battery operated transistorized equip ment You ll wonder how you ever solved your power supply problems be fore you discovered Mini Reg 85 Stop Static Continued from page 69 What can be done First current spikes from digital logic may be re duced by bypassing ICs with 1 mfd ceramic capacitors These capacitors are applied as closely as possible to the power pins of the various IC pack ages Another scheme that is successful at frequencies below 1 MHz is the use of a parallel power distribution system as shown in Figure 6 Since I1 and 12 cannot flow in R or L they produce no troublesome noise In order for this system to work well however the power supply must have a low imped ance and be connected to points A and B via very short wires Now in most instances you don t need to worry about how to distribute power in a project all the interconnec tions are established on the author s PC board and you just copy that layout This eliminates a lot of trial and error and makes your life that much simpler in the process Using a PC board and following the construc tion practices that we ve discussed here you should be able to turn out a perfect project every time a Antiques Restored
31. In Figure 2 the two possible methods for shielding are diagrammed Figure 2A shows a con ductive metal shield grounded to source common that completely encloses source Electric field coupling be tween source V1 and the shield is sym bolized by capacitor Ci Outside the shield another stray capacitance C exists between the shield and the equiv alent parallel resistance RG2 RIN The rest of the amplifier has been deleted because so far aS we are concerned here its only important characteristic is RIN An electric field exists within the shielded enclosure however the field utside the shield 1s zero every 68 SHIELD A Figure 2B SHIELD B A grounded shield is very effective against capacitive ccupling The shield may be applied either around the noise source A or around the circuitry where noise is being picked up B Aluminum is good here but not against low frequencies where This comes about because at least ideally the entire surface of the shield remains at ground potential Since the external field is zero no en ergy is transferred across stray capaci tance C2 In part B of Figure 2 the grounded metallia shield envelops the receiver Energy transfer occurs between source Vi and the grounded shield via Ci The field within the shield is zero since the shield is at ground potential As a result no noise is picked up by the receiver Any metallic sheet makes a good
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33. Moreover during periods rear the peak of a sunspot cycle frequen cies not normally bent by the iono sphere may open up for long distance work For example during a sunspot cycle peak in the late 1950 s TV DXers in New York were able to bag TV sig nals from a Hawaiian TV station op erating on channel 2 55 25 59 75 MHz Solar Weather Sunspots were one of the first things noted by Galileo when he began surveying the heavens with his telescope His first recorded observation of sunspots happened in August 1610 and the puzzled Galileo speculated that the spots were the re sult of spent fuel ejected from the sun Today we know that sunspots repre sent intense disturbances deep within the sun They can be thought of as thunderstorms on the sun While sunspots appear as dark areas upon the solar disc they are actually over 100 times brighter than our moon It is Skylab astronauts took this photo of a solar flare using an EUV extreme ultraviolet spectroheliograph to measure the intensity only by comparison with the brighter solar surface that they seem to be dark Sunspots have a dark nucleus called the umbra and a lighter surrounding area called the penumbra These areas are less bright than the rest of the sun because they are approximately 1500 F cooler than the usual temperature of the solar surface While sunspots seem to be small compared to the sun some may measure over 30 000 miles in width many times t
34. START YOUR OWN BUSINESS dise Catalog Details Free Worldround P Medina WA 98039 EVERYONE a prospective customer Show our line of belt buckles badges and accessories to truckers police firemen postal carriers taxi and bus drivers and others Personalizations available Over emblems available Hook Fast Box 1088 IN Provi dence RI 0 WATCHES WATCHMAKING amp REPAIRING WATCH and clock repairing books tools materials Free Catalog North American Box 77 EE4T Fox River Grove IL 680021 98 Simply BASIC Continued from page 70 oddsmakers whose prognostications ap pear in your local newspapers Gamble allows you to plug in as many performance factors as you need in order to estimate the relative per formance between contenders in a sporting event You assign a relative value to each performance factor Then you rate each team player or even horse for its individual performance for each performance factor Note Some Basics cannot handle more than 10 entries for one subscripted variable hence you will be limited to 10 teams and factors unless you modify the pro gram by adding a DIMENSION statement For example to enter up to 50 teams or factors add the following line 168 DIM F 50 T 50 S 50 Your only limi tation on entries is the amount of RAM available in your computer Our sample run is for a baseball game and while we know the old adage that On any given day
35. Square Wave Generator and Signal Injector Circuits These are not unprofessional breadboard experiments but genuine radio Circuits constructed by means of professional wiring and soldering on metal chassis plus the new method of radio construction known as Printed Circuttry These circuits operate on your regular AC or DC house current THE EDU KIT IS COMPLETE You will receive afl parts and instructions necessary to build twenty different radio and electronics tir cuits each guaranteed to operate Our Kits contain tubes tube sockets variable electrolytic mica ceramic and paper dielectric condensers resistors tie strips hardware tubing punched metal chassis Instruction Manuals hook up wire solder selenium rectifiers coils volume controls switches solid state devices etc In addition you receive Printed Circuit materials including Printed Circuit chassis special tube sockets hardware and instructions You also receive a usefui set of tools a professional electric soldering iron and a self powered Dynamic Radio and Electronics Tester The Edu Kit also includes Code Instructions and the Progressive Code Oscillator in addition to F C C Radio Amateur License training You witt also receive lessons for servicing with the Progressive Signal Tracer and the Progressive Signal Injector a High Fidelity Guide and a Quiz Book You receive Membership in Radio TV Club Free Consulta tion Service Certificate
36. TENNIS game board just off production run These boards contain a 5V 1A power supply less xformer a TV come puter interface modulator plus 16 or 20 74L series IC s amp a handful of other components Complete with schematic for a TV Tennis Handball game etc Instructions are included for using the 5V 1A power supply Sh WtBoz 8130322 6 88 for 17 88 8T30322 17 88 3 t TRANSFORMER for power supply N ARETE TT ee L RAE Ae da ame yi Retail Stores 119 Foster gom fass 01960 or our NEWEST store THE TOWN DUMPE INC next to WOOLCO 777 Willowlik St Manchester New Ham 1 des Pe cane a Reuse add postage AH is F O B Peabody Ma No C O D s please Massachusetts Residents add 5 sales tax OHOEHS WE UME Use your Bank Americard Master Charge or American Express Credit Card 10 00 min on all charge orders B amp F ENTERPRISES 3 DEPT E 121 3 119 Foster Street Peabody MA 01960 617 531 5774 Kn SAVE WITH BURPLUS Computer Readout Continued from page 52 buffer and then either to a printer or a mass storage device The user can then retrieve at his convenience the infor mation which has been saved Digicasting will provide an inexpen sive means of linking a home computer into a large continuou
37. ae CENTER 93185 GM 1 6 3V 5 2x2 5x25 4 495 9 00 cmt DUAE 98885 34V SAct 6 0 92A 3x3 x4 9 1195 22 00 the personal computer will change from eines READING RES ZR INOA inhik P IE do h dis onal Bhd ak Ne iy METER 67575 ABV 2Act 60 G 5 49 439 3 7 95 16 00 what was mostly ucational an aee 67685 48V Q6 5Act SAV 26 441423 9 10 95 20 00 fascinating toy into a truly useful home kat 3 9 V Ta E er er COMPLETE with 4 scales 1 3 4 0 1 NA volta 2 1060 3 190 DB 4 10 to HF Gain Meter hae a plastic case with Each removable scale Size 4 4 h x Ww N 225 99909909090909909090909090909090900900090090900990000009909090999 SMALL GENERAL PURPOSE appliance It is however a kind of ap pliance nobody really expected it to be e 3 t Thi 11 f a PT eM 6 or 12V 1 25 multitude of requirements when it was first introduced One is B oT T ther amp or 1 25 x vos O MODE 25 t Primary ts wired t Men reminded of the eighteenth century sci T Tl v 1 i i a li used as on Isclation winding entist who was asked of his recent IV Mal e e giat v E er Bh x Du a di Of wh is it His 10 or 0 to Meter has a taut U Wt 1 lb No 66235 med what use Is It His reply 8 9 gach with o rema sate 900800000000000000000000000000000000000000000000000000000000
38. amount of voltage induced in the secondary winding depends on how many turns of wire the secondary contains compared to the number of turns of wire in the primary winding So if the secondary has only half as many turns as the primary winding the voltage will be stepped down to half its original value If the secondary has twice as many turns as the pri mary the voltage will be stepped up to twice its origi nal value The difference in the number of turns is known as the turns ratio of the transformer If the primary wind ing has N turns and its voltage is E the secondary winding with N turns produces voltage E EON The power consumed the secondary circuit of a transformer must be supplied by the Primary Since the voltages are constant in each circuit the current in the Primary circuit must vary to supply the amount of power demanded by the secondary Current in the Primary depends on the current drawn in the second ary circuit A TRANSFORMER WITH NO LOAD ACTS LIKE AN INDUCTOR PRIMARY SECONDARY WINDING WINDING SOURCE 79 QUESTIONS 1 1f a transformer primary has 1 000 turns and the secondary has 6 500 turns what is the turns ratio 2 If 85 volts is applied to the primary winding of the transformer in Question 1 what is the voltage at the secondary 3 What would happen if the leads were reversed and 85 volts was applied to the 6 500 turn coil 4 What happens if 13
39. and REMs This is a veritable potpourri of computer programs Each game is listed and a sample run given PUBLISHER S ADDRESSES John Wiley and Sons Inc 605 Third Ave New York N Y 10016 People s Computer Company P O Box E Menlo Park Calif 94025 Creative Computing Press P O Box 789 M Morristown N J 07960 Engel Enterprises Box 16612 1 Tampa Florida 33687 Hayden Book Company 50 Essex St Rochelle Park N J 07662 This new edition is truly an improved model The games have all been de bugged and most importantly rewrit ten all in the same language the Altair version of 8K Basic from MITS This is a Basic which calls for very little if any conversion to run on almost every personal computer Even better the listings are now ultra clear and easy to read t Take heart there are a new series of publications just arrived authored by Dr C William Engel which can be run in 4K with a Tiny Basic such as Radio Shack s Level One While the volumes are thin they are among the best in the field as far as quality of the games Stimulating Simulations from Engel Enterprises Box 16612 I Tampa Flor ida 33687 is little short of invaluable to the computer gamer Though it con tains but ten programs for 5 00 this little book is full of exciting extras For one thing every program is completely flowcharted If you are learning Basic and just getting into programming the educati
40. antique radio museums and other miscellany OUR REGULAR DEPARTMENTS 4 Hey Look Me Over 14 Bookmark by Bookworm 16 Hi Fi Reports 24 Newscan 26 Ask Hank He Knows 59 Test Bench New Products 65 Getting Your BNEE Third Semester 95 Literature Library vv Cover Stories a pes TRANSFOR MER TECH Y LT acm R rd E f 2 HY oc C HIGH FIDELIT PROJECTS em CO AU bg bd Count akya mputes touc OF SUNSPOTS AND She ng Super DA Hum Rake g AUTHORS IN THIS ISSUE rur James A Fred Larry Friedman ai Harry L Helms Jr Don Jensen Matt Viner ii n Jeff Jonas Randall Kirschman Adolph A Mangieri Kathi Martin Hank Scott Gordon Sell Neil Shapiro Walter Sikonowiz Tom Sundstrom Tom Williams and the ELEMENTARY ELECTRONICS Staff Pasar pew T tot CRS ps b ELEMENTARY ELECTRONICS January February 1979 Your taste is showing Whatever you buy it has to be the best When you buy a CB radio it has to be a President Because anything less is not quite up to snuff The Thomas J for example It s our finest 40 channel AM mobile unit The cr me de a creme It has unsurpassed receiver selectivity and sensitivity And talkpower that s becoming a highway legend Thirteen knobs and switches put you in total command of this impressive performer They include mike gain as well as RF gain delta tune noise blanker ANL switch even a panel light dimmer switch
41. any baseball team can beat any other team it does serve for a good example That s why vou shouldn t bet on a baseball game We show five factors for two teams though if we were handicaoping a horse race we could show perhaps six factors for seven horses Okay now run all of this weekend s sporting events through your computer and see how your handicapping stacks up against the actual outcome of the games and races B HOW MANY TEAMS ARE BEING RATED 2 TEAM 1 BUFFALO BEARS TEAM 2 7 GREENPORT GIANTS RATE EACH TEAM FOR EACH FACTOR ON A SCALE OF 1 5 1 BUFFALO BEARS PITCHING 4 HITTING 5 FIELDING 4 BASERUNNING 3 BUNTING 4 RELATIVE PERFORMANCE FACTORS PITCHING POINTS 26 HITTING POINTS 25 FIELDING POINTS 16 BAS ERUNNI NG POINTS 9 BUNT ING POINTS 4 TOTAL RELATIVE PERFORMANCE FACTOR 74 GREENPORT GIANTS PITCHING 2 HITTING 4 FIELDING 3 BAS ERUNNING 3 BUNTING 5 RELATIVE PERFORMANCE FACTORS PITCHING POINTS 18 HITTIAG POINTS 26 FIELDING POINTS 12 BAS ERUNNING POINTS 9 BUNT ING POINTS 5 TOTAL RELATIVE PERFORMANCE FACTOR 56 READY f STATEMENT OF OWNERSHIP Statement of ownership management and circulation Act of August 12 1970 Section 3685 Title 39 United States Code of Elementary Electronics pub lished bi monthly at 380 Lexington Ave New York NY 10017 for October 1 1978 Annual subscription price 6 95 Publication No 172540 General business office
42. at a given frequency KR AS gi NA P RAS w sts d S wow a ly En e LAST Tp T T Bae D Lu E 3 r So v R L L t amm HE BE TET NUN iA o Q 0 Tod T sl r m wa a EF tu RS vu i p oe id Y a he IMT RL 1 Y Li J la a Da i te A La CS ap my 7 a 5 3 n SM KS vR ain D a a E p La Los N r QUESTIONS 26 A coil with an air core has a greater smaller in ductance than a similar coil with an iron core 27 Inductive reactance is the result of a constant changing magnetic field 28 How would you increase the inductive reactance otf of the device illustrated on the opposite page 29 What effect would increasing XL have on the bright ness of the lights 30 How should the core be set to obtain maximum brightness of the lights 31 Would this device work with a DC power supply ANSWERS 26 A coil with an air core has a smaller inductance than an iron core coil 27 Inductive reactance is the result of a changing magnetic field 28 Push the iron core into the coil 29 Increasing XL would dim the lights 30 The iron core should be totally removed 31 The device would not work with DC WHAT YOU HAVE LEARNED 1 The changing magnetic field produced by the pri mary winding in a transfor
43. can be a wire steel or cop per bar or almost any material that will offer the proper resistance To de termine the needed shunt resistance we will consider an example If we want a O to 10 milliammeter to be able to read full scale for a current of 10 amps Therefore 10 mA will flow through the meter when 9 990 Amps are diverted through the shunt If the meter resist ance was 100 ohms using Ohm s Law the voltage across this parallel circuit is found by using the following equa tion E Current Resistance 10 3 100 ohms Volt Using the calculated voltage and 40 IGH AMP METER Meter Resistance Determination meter 2 R3 R2 0 10000 0 10000 POWER SUPPLY To determine the internal resistance of a meter construct a circuit like the one illustrated above If you don t have the parts in your junk box then check an electronics surplus outlet A shunt resistor bypasses the bulk of the current around the meter while allowing a regulated amount to pass through the meter s coil and give an accurate reading A shunt can be a resistor or a measured length of wire Make sure it will handle the current Shunt Hookup METER COIL RESISTANCE R meter IOO OHMS P AMPS K wd IO AMPS L R shunt 0 10 OHMS 9 99 AMPS SOURCE LOAD EXTERNAL SHUNT In this case the milliammeter would be capable of giving a readout directly in amperes solving Ohm s Law for resistance the
44. coil or around the edge where the cone is cemented to the metal basket Re cement the cone or small holes in the cone larger holes or tears can be re paired with speaker cement and strips torn from a paper towel Speaker ce ment can be purchased at Radio Shack stores If the sound is distorted or raspy you may have dirt or iron filings in the space between the voice coil and pole piece This is difficult to re pair and you may have to buy a new speaker By now your radio should be work ing quite nicely unless you have a rare fault in some component If it is you can put it back into its cabinet If you have replaced the grill cloth put the speaker back and mounted the dial escutcheon you can put the chassis back in place Install the knobs after polishing them and replace the back if there is one Now turn the radio on sit back and enjoy the real old fash ioned tone of a tube type radio Now really doesn t it sound much better than your transistor radio with its 2 inch loudspeaker Antique Plastic What you say you have looked all over and cannot find a wooden cabinet radio to restore All you could find were sets with plastic ELEMENTARY ELECTRONICS January February 1979 up et cabinets covered with dirt paint spots grease and scratches all over the cabi net well tell you what to do Buy the oldest plastic cabinet radio you can find and practice on it and one of these days you will find a wood
45. ed or reflected back towards the trans mitter and never gets into the ether or the other guy s headphones Al most all of today s commercially de signed ham equipment is meant to work into a 50 to 75 ohm load That means that the transmission line and antenna should be designed and adjust ed so that they will present a 50 to 75 ohm impedance across the output terminals of the transmitter in the same way that most audio amplifiers specify an 8 ohm load in terms of speaker resistance impedance Basically an SWR of 1 1 indicates to you that close to 100 of the out put power of the transmitter is flowing out of the antenna while one of 3 1 indicates that only about 3396 of the transmitter s power is actually getting out onto the air Wattage doesn t come cheaply so be sure to make the most of what your transmitter has to offer While we don t advocate the pur chase of a lot of extraneous equip ment especially for the novice there are certain pieces of equipment that no ham shack should be without SWR Meters SWR meters do not have to be expensive Some of the smaller SWR meters marketed for CB will cover 3 to 30 MHz and they will do just fine check the power handling capability SWR readings are relative All that you have to remember is that you want maximum forward and minimum re r THE FIRST TWO PARTS of this e i _ D CIRCLE 1 ON READER SERVICE COUPON Z flected power On a meter the ide
46. etc The receiver scans only the groups punched up Individual channels in each group can be locked out by pressing the lockout key The group scanning can be in any order for example if the 10 and 40 keys are depressed the receiver will scan channels 1 through 10 and 31 through 40 An individual channel is manually selected by simply pressing the key corresponding to the channel number and then the manual key Direct selection of channel 15 would be selected by pressing keys 1 5 and manual ELEMENTARY ELECTRONICS January February 1979 E oA ELEMENTARY ELECTRONICS has been able to obtain some of the latest 40 channel CB transceivers for review and presents the test reports here These units are not prototypes but are stock standard the same as the transceivers that you can buy over the counter If you don t find the particular unit you are interested in reported on here check for the 1979 edition of CB YEARBOOK soon to be on the newsstands e COBRA 142 GTL 379 95 Dynascan Corp General Description A 40 channel AM SSB transceiver for mobile P A base operation Fine tuning 1 kHz is provided Power supply is 12 to 13 8 VDC with negative or positive ground and 120 VAC Over all dimensions are 5 in 13 in W x 13 in D There are front pan el controls for channel selection volume squelch Dynamike RF gain SWR CAL and Voice Lock fine tune Switches for CB PA noise b
47. for easy reading day or night Turn the meter mode selector and read signal strength received relative RF power output modulation or standing wave ratio all from the same big precision meter In addition to the digital channel display there s an LED to tell you when you re switched to Channel 9 Another LED tells whether you re receiving or transmitting Still another lights up if you have an antenna problem Inside the Thomas J looms President s advanced electronic circuitry that puts it right at the top of anybody s list for performance and dependability better than none at all buy the cheapest If it must be the very best or none at all buy the President PRESIDENT Engineered to be the very best 16691 Hale Avenue Irvine CA 92714 714 556 7355 In Canada Lectron Radio Sales Ltd Ontario CIRCLE 17 ON READER SERVICE COUPON Hey look me over Showcase of New Products Musicians Only Organtua an innovative extension of combo organ technology designed by Craig Anderton is now available from PAIA Electronics Unlike the thin sound of single voice combo organs Organtua has three individual ranks each with a five position octave switch for a thick textured sound The multi voice feature allows ranks to be detuned slightly for flanging or chorusing effects or ranks can be tuned to wider intervals CIRCLE 69 ON READER SERVICE COUPON such as the 4th or 5th to simulate draw bar
48. from page 35 Using old observatory records astron omers have been able to compute a sunspot number for each year since 1749 If sunspots cam be thought of as solar thunderstorms solar flares are the sun s lightning Solar flares usual ly occur near sunspots and are more common during periods of high sun spot activity Like lightning flares are very short lived events Sunspots may last for several weeks while flares usu ally last less than an hour Flares re semble a tongue of flame leaping up from the sun s surface from a sunspot or from one sunspot to another A solar flare can severely disrupt ra dio communications by causing a sud den ionospheric disturbance SID When a SID occurs all shortwave fre quencies between 3 and 30 MHz may become completely useless for long dis tance communication for periods of up to an hour During a SID it s not un usual for electronics technicians to be swamped with calls from hams SWLs and commercial users of the shortwave bands who all complain that their equipment is not working Solar flares cause SIDs because they release enor mous quantities of X rays When these X rays reach the lower regions of the ionosphere around 60 80 miles they cause ionization much like ultraviolet light does Yet X rays cause ionization much heavier than does ultraviolet light In fact the ionization is so dense that the ionosphere begins to absorb all shortwave signals inste
49. games of skill and chance are explained and then it is up to the reader to sit down use what he or she has learned and actu ELEMENTARY ELECTRONICS January February 1979 ally program the game s for the com puter Some are fairly easy to do but many of them are dyed in the wool Basic Course Continued from page 82 secondary circuit of an ideal transformer 4 Most transformers have an efficiency of nearly 100 so very little power is Jost in them 9 Transformers alter the impedance of a load The stinkers There are no solutions given so it s like a final exam in computer gaming turns ratio core Why not get in on all the excitement Learn to speak Basic it s the language of fun all over the world H change in impedance depends on the square of the 6 Magnetic amplifiers control the inductive reactance of a coil by altering the magnetic property of its i 7 A very simple magnetic amplifier is basically a coil with a removable iron core When the core is in serted XL increases and the power supplied to the load decreases Mini Reg Continued from page 45 another five volt supply split the cir cuit supply lines and protect those de Vices you cannot spare with the Mini Reg Almost any circuit operating off three volts can safely operate at 3 4 volts The output voltage can be further re duced by connecting a low voltage zener diode in series with the plus l
50. helds marine Communi cations equipment and antennas and accessories 345 For CBers from Hy Gain Electronics Corp there is a 50 page 4 color catalog base mobile and marine transceivers antennas and accessories Colorful literature Illustrating two models of moni tor scanners is also available 354 A government FCC License can help you qualify for a career in electronics Send for Infor mation from Cleveland Institute of Electronics 355 New for CBers from Anixter Mark is a colorful 4 page brochure detailing their line of base station and mobile antennas including 6 models of the famous Mark Heliwhip 356 Continental Specialties has a new catalog featuring breadboard and test equipment for the professional and hobbyist Descriptions pictures and specifications aid your making a choice 359 Electronics Book Club has literature on how to get up to 3 electronics books retailing at 58 70 22 for only 99 cents each plus sampie Club News package 361 Solving CB Noise Problems is published by Gold Line and tells you how to reduce the noise and get a clearer signal In discussion and dia gram you can find out about the kinds of noise their sources and the remedies want this catalog of surplus bargains industrial military and commercial electronic parts all from Allied Action 365 Electronic Supermarket has a new Catalog of almost everything in the field transformers semi conductors tv parts
51. level high impedance stages are often the most susceptible While the source and receiver may belong to two different pieces of equipment they may just as well be different stages of a single piece of equipment Coupling In order to transfer en ergy from the source to the receiver some form of coupling must exist The two important modes of coupling con sist of an electromagnetic field or a common ground impedance between the two circuits in question Considera tion of an electromagnetic field is usually broken down into two subcases el electric field coupling and magnetic field coupling A high voltage low current circuit radiates energy chiefly through an electric field whereas high current low voltage circuitry radiates predominantly through a magnetic field Most noise sources radiate through both fields but it is easier to deal with one field at a time Let s begin with electric field coupl ing also known as capacitive coupling In Figure 1 we have voltage source Vi with internal impedance Rai driv ing a load RL This voltage generator might be anything a transistor op amp logic gate or even an alternator the exact nature of the source is un important Nearby we have a second voltage generator Vz with an internal impedance of Ree An amplifier with input impedance equal to RIN is sup posed to amplify V However electric field coupling between the two circuits exists through stray capacita
52. monolithic crystal filter we sell it at a price you wont have and a ceramic filter to reduce inter second thoughts ex about ference and improve reception By improving the transmitter Pa 5 circuitry the 29GTL keeps you obra punching through loud and clear Punches through loud and clear By incorporating new features for Cobra Communications Products better reception everything you 6460 TRR 6008s copy comes back loud and clear HP Write for color brochure ire Plainview N Y CANADA Atlas Elect CIRCLE 8 ON READER SERVICE COUPON ew Avanti Astro Fantom the perfect CB antenna for conve nc E a AVANTY antennas z m THE STAFF Editor in Chief Julian S Martin Managing Editor Alan H Rose K2RHK Technical Editor Gordon Sell KBDA1464 Associate Editor Lee Lensky KAJR2410 Citizens Band Editor Kathi Martin KGK3916 Editorial Assistant Cynthia McClean Workbench Editor Hank Scott Art Director Ralph Rubino Assistant Art Director David Pindar Cover Art Director Irving Bernstein Art Editor Joe Groom Art Assistants Celeste Barbera Michael Vessio Leslie Wallant Advertising Manager Ralph Vega Advertising Research Associate Jyll Holzman KAKZ1490 Production Director Carl Bartee Production Manager Carole Dixon Production Assistant Annette Simon Newsstand Circulation Director Don Gabree Subscriptio
53. of the big city stations and the uplifting programs and classical music of the national government s shortwave voice On Colombia s great plain where beef is king you ll hear numerous ranchera selections music more Mexican than one would expect Programming from the many Co lombian shortwave stations is almost exclusively in the Spanish language I think almost any SWL who is willing to put forth the effort can in time manage to pick out the identifi cation announcements even in Spanish Here are a few of the Colombian short wave outlets you may hear Radio Nacional This is the short wave outlet of the national govern ment and broadcasts from Bogota capital of Colombia This has been widely heard on 15 335 kHz approx imately with programs that tend to be a bit more on the highbrow level than the typical Latin American station Don t be surprised to hear classical se lections from this station One of the rare opportunities to hear English on a Colombian station is the English Span ish lesson at 1045 GMT Radio Sutatenza This shortwave station may be the beginner s best bet for logging a Colombian SW er Radio Sutatenza in Bogota is owned and op erated by a Roman Catholic organiza tion dedicated not only to religious goals but also to social and educational improvement At 50 kilowatts of pow er it is one of the stronger stations in South America Perhaps of equal im portance is the fact that Radi
54. ohms in the cir cuit shown We can now represent any digit by various combinations of or off of the seven switches There is a poten tial for 49 different character displays with this set up well beyond the needs of a numeric display So by using a common integrated circuit chip we can reduce the number of switches to four The internal cir cuitry of the BCD to seven segment de coder the name will make more sense later as the chip is called takes the 61 G DIGITAL COUNTING combinations of the four ons and offs and applies power to the ap propriate LED segments This repre sentation of a digit by four combina tions of and off is called Binary Coded Decimal or BCD for short A binary number uses only zero and one rather than zero through nine The one can be represented electronically by a high level voltage and the zero by a low level voltage The following chart shows decimal numbers their BCD equivalent and the segments that are lit on a numeric display We now have a circuit that can translate computerese BCD number ing into the decimal numbers we have used all our lives Learning to Count Now we need to teach our circuit to count from zero to nine We can do this by adding an integrated circuit chip called a decade counter This integrated circuit has one input line and four outputs The out puts as you have probably guessed are connected to t
55. proper shunt can be found This deri vation is shown below Voltage By following these few simple steps Current you will greatly expand the versatility i o Volt of your test equipment It will increase 9 990 Amps your ability to handle a greater variety 1001 Ohms of test and trouble shooting situations ELEMENTARY ELECTRONICS January February 1979 T ban are I P ai rte ton Eeun ay Pm v ms ee m EST Q Lum d TH ANTIQUE RADIOS by James A Fred Put that flea market eyesore back in showroom shape BUDGET ELECTRONICS telling where to find how to buy and how to sell old radios Since then many readers have written to me asking just exactly how to go about restoring an old radio There are several levels of restoration and while one collector will be happy just to have his radio play many others want the set to look and play like it did the day it was shipped from the factory In this story I will tell you how to refinish the cabinet and restore the radio to playing condition If you want to stop at any point along the way that is your privilege N TIME AGO I wrote a story for Break It Down First you must find a radic The one 1 show you in this story is a five tube Airline Mont gomery Ward wooden cabinet table model made around 1935 It cost 1 50 at a farm auction It did not play but for this price
56. pulse or level transitions replacing separate level detectors pulse detectors pulse stretchers and pulse memory devices All for less than the price of a DVM LP 2 LOGIC PROBE 24 95 LP 2 performs the same basic functions as the LP 1 but for slower speed circuits and 1978 Continental Specialties Corporation R r Prices specifications subject to change without notice without pulse memory capability Handling minimum pulse width of 300 nanoseconds this 300 K ohm probe is the economical way to test circuits up to 1 5 MHz It detects pulse trains or single shot events in TTL DTL HTL and CMOS circuits replacing separate pulse detectors pulse stretchers and node state analyzers LP 3 LOGIC PROBE 69 95 Our LP 3 has all the features of the LP 1 plus extra high speed It captures pulses as narrow as 10 nanoseconds and monitors pulse trains to over 50 MHz Giving you the essential capabilities of a high quality memory scope at about 1 100th the cost LP 3 captures one shot or low rep rate events all but impossible to detect any other way All without the weight bulk inconvenience and power consumption of conventional methods r IA m ur a 1 4 e kz dE j a c e E F Use CSC s highly versatile logic probes for testing debugging or servicing any type of digital circuit They give you a lot of information about IC circuit conditions and help you do mo
57. six inch cube and inside is an old Jewell multi range voltmeter If I might digress a moment I would like to mention that cedar cigar boxes were once the favor ite enclosure for many kinds of home made radio gadgets L have found nice ELEMENTARY ELECTRONICS January February 1979 crystal radio receivers built into cigar boxes have seen radios built on cigar box chassis Cigar boxes used to come in many sizes and shapes If you enjoy going to flea markets and antique shows cedar cigar boxes are often for sale but prices are going out of sight You will also find vendors with thou sands of cigar box labels You can make your own replica cigar boxes and glue the available label on if you can t find the real old ones Shun the modern cigar boxes however because they are solid cardboard covered with paper You will usually find DC voltmeters made in two basic types You will find voltmeters made in D Arsonval mov ing coil and iron vane movements Most of the inexpensive nickel plated or watch case meters had iron vane movements Iron vane meters need an appreciable amount of current to move the pointer from zero to full scale reading This was OK when radio men 73 a a ANTIQUE RADIO CORNER were measuring battery voltages and wanted a moderate load on the bat tery but later when it became neces sary to measure plate voltages in re sistance coupled amplifiers the iron vane meter was worthless You may wonder
58. stereos speakers boards phones wire and cable tools motors 366 How about a hybrid 13 watt audio module for 8 88 Or ultrasonic transducer for 1 49 You find these and other exotic parts and products aplenty in Poly Paks flyer Get your copy now 367 Optoelectronics new catalog features their new Frequency Counter a 6 digit clock calendar kit mobile LED clock biorhythm clock digit con version kit and many others 371 Your computer system needn t cost a fortune Southwest Technical Products offers their 6800 computer complete at 395 with features that Cost you extra with many other systems Peripheral bar gains are included here 372 See how you can save with Olson s Erector Kit Computer System also their factory wired ver sion which includes a 2 volume Bell amp Howell instruction course Send for information 373 ETCO has a Grand Opening Catalog which anyone in the electronics field shouldn t miss Full of all kinds of products from surplus and warehouse sales they claim everyone is a bargain 474 Radatron s Catalog 1006 lists many projects from a self contained portable lab station for an electricity electronics course to many texts lab manuals and applied activities 375 Compucolor Corp has a personal computer system with an 8 color integral display a type writer like keyboard and a mass storage device Programs are ideal for checkbook and income tax figuring 376 Sparkomati
59. this article Get ready you re about to pretend you re a computer This may seem a strange thing to do but you ll find it s really quite logical Look at lines 100 through 200 of the program Note that all four begin with REM As a computer you know this means Remark and that you re not sup posed to pay any attention to these lines They are there simply for the benefit of any human readers Move along to lines 210 through 240 These are PRINT statements and you know this means to print them out onto your teletype or CRT screen These lines let you tell your human friend the rules of the game While your human pal is plodding his way slowly through the rules as a computer you are using your time wisely You ve ignored the REM at line 300 and gone on directly to line 310 Here at line 310 you do your first real bit of computerized thinking You pick a number call it X the value of it being INT 100 RND 0 1 The RND tells you to generate a random number the parenthesized zerc tells you the random number should be between zero and 1 The INT is ar Integer command which tells you tc simply chop off any numbers to the 53 2012 puran run right of the decimal point In other words You will let X be the integral value of a random number between 0 and 1 multiplied by 100 and with 1 added to it Why Well it had to be an INT com mand because in line 210 you told your human you would pick a whole num ber and com
60. to zap many de vices if you make an error If you have Continued on page 85 45 The Big NEW HEATHKIT Christmas Catalog is just off the press Read about all the exciting new products you can give or get for real kitbuilding fun and satisfaction We re the world s biggest and best source of quality money saving electronic kits Computerized Weather Monitor If you need weather information for ANY purpose the ID 4001 is the way to get it This microcomputer based weather instrument digitally displays time of day in 12 or 24 hour format wind direction and magnitude indoor and outdoor temperature barometric pres sure even wind chill factor What s more the computer s memory stores the highest and lowest data for each function so you can recall it for easy and accurate record keep ing Chart recorder and computer outputs provide even more versatility Includes remote transmitter with windcups and weathervane that have been wind tunne tested and an outdoor temperature sensor using the latest infra red technology Digital Readout Car Clock with Trip Timer Versatile clock timer for any vehicie shows time in hours and minutes has 24 hour timer that reads to nearest second Bright easy to read display low power circuit doesn t drain battery Hand Held 2 Meter Transceiver Superb features specifications and a great low e b price make the j VF 2031 a terrific buy in a hand
61. tor 2 01 ER TABS m muttiturn 9 slngts turn O i Meg m WE FIGHT OD MAY VE AC LEDS ONE ENSE Add Dee LM EO aoc YOUR CHOICE 5 for 1 00 h 1 SALE 10 for 1 01 one Wakefield Rated net 30 Retail 16 18 Del C 55 ee 245 3828 52108 Order Cat No rmine St Wak Dx efiel esate lz Sons maas ip MINIMUM ORDER e oo Z lor ibd 1802 MICRO SINGLE PIN RED N 1 6 for 1 01 1948 MICRO YELLOW D af 1 6 for 101 Bs hw agnt a 2436 JUM i eio Lol G 2137 MICRO RED E PC FREE P O BOX 942 N 1 6 for 1 01 D 2790 JUMBO RED CLEAR __ CATALOG SO LYNNFIELD MA x _ 01940 EE RR y y y A You ll only pay more Shop mail order n save LINEAR I C S LM324N 49 Quad Op Amp LM339N 49 Quad Comparator LM555N 8 29 Timer LM556N 14 59 Dual Timer LM723CN 34 Voltage Regulator LM723CH 39 Voltage Regulator LM741CH 37 Op Amp LM741CN 8 24 Op Amp LM1458N 8 39 Dua Op Amp TTL LOW POWER SCHOTTKY PLASTIC DUAL IN LINE 1 Part No Price Part No Price Part No Price Part No Price No Price PartNo Price 74LS00 15 74LS47 89 7405123 79 74LS170 125 74LS258 75 74LS368 55 74LS01 15 744548 89 74LS124 99 74LS173 95 7415259 145 7415373 1 75 74LS02 15 74549 89 74451725 59 74LS174 69 74LS260 29 7415374 175 74LS03 15 744551 19 74451726 59 7415175 69 7ALS261 185 74 5375 65 74LS04 19 744554 19 7415132 79 V
62. tubes if you keep the transmitter in the tune mode for too long a period of time fail to keep the transmitter in reson ance or have too high an SWR You can build an antenna tuner one is described on pages 98 and 99 of Simple Low Cost Wire Antennas by Orr and Cowan and published by Ra dio Publications Inc Box 149 Wilton CT 06897 for relatively little money but if you elect to buy a commercial unit shop carefully because features vary Some of the low cost units tune only CIRCLE 82 ON READER SERVICE COUPON INDUCTANCE TRANSMITTER 3 4 MFJ Enterprises offers a variety of antenna tuners starting around 40 00 for a simple end fed long wire tuner Pictured here is one that will handle all types of feedlines from 10 to 160 meters Some models are offered with and without built in SWR meters The MFJ 941 is priced at 70 00 and will handle 200 watts input power ELEMENTARY ELECTRONICS January February 1979 65 2 a 3RD SEMESTER an end fed long wire yet one of the most expensive units tunes only coaxial cable There are a number of multi purpose tuners in the 80 to 130 range These will handle a long wire coaxial cable and open wire feedline The price of the units varies in proportion to the power handling capability of the tuner You may wish to buy an antenna tuner that will handle 1 or 2 kilowatts if you intend to purchase a linear amplifier once you upgrade your ticket By the way don t be fooled
63. twisted pair especi ally at high frequencies is coaxial cable for most hobbyist requirements however a twisted pair is sufficient to reduce magnetic radiation Finally changing the orientation of the source with respect to the receiver often helps Consider for example the magnetic radiation from a power transformer You may carefully twist the leads but you cannot do anything about the mag netic flux from the transformer coils Usually however some mounting ori entation of the transformer will result in minimized pickup in your noise sensitive stage Comparing magnetic coupling with electric coupling one thing you may have noticed is that the impedance of the receiver has no effect on its sus ceptability to inductive coupling Also you may have wondered whether a shield would be as effective against a magnetic field as it is against an elec tric field The answer is no Aluminum which is so effective as an electric shield begins to be effective against magnetic fields only at higher frequen cies above 100 KHz At the important frequency of 60 Hz aluminum is use less In order to obtain better magnetic shielding your shield must be a fer romagnetic substance such as steel Because it is harder to machine than aluminum steel is rarely used by hob byists even though its magnetic shield ing properties are superior to those of aluminum At 60 Hz however even steel is only partially effective shieldi
64. typical digital numbering circuit There are hundreds of other combinations of A T a s Pa Ke s E r E ih s e E s e e gt vn lt o v a P K a J The connections appear complicated but once you understand the principles involved they all will make sense Note the despiking capacitor added to stabilize the circuit 64 similar integrated circuit chips After you have worked with these circuits for a while you will begin to understand the system better and will find yourself designing more and more complex cir cuits If you want to extend the number of digits much beyond two or three this technique starts to get very ex pensive and you should consider mul MONO STABLE MULTIVIBRATOR SUCH AS 74121 If the output of a mechanical switch were put straight into a counter each one of the contact bounce pulses would trigger a cycle of the counter The monostable multivibra tor triggers as the pulse first goes high The output remains high for a time longer than any continuation of bounce pulses so the unit only counts once The pulse widths are typically measured in nanoseconds H6 IC3 7 Books No tiplexing the circuitry but that is an other article altogether To describe it as simply as possible multiplexing is the running of many displays off a sin gle BCD to seven segment decoder Power goes to the display digit only wh
65. very large banks of data called data bases It is in this applica tion that one is dealing primarily with text material Personal computers can now be linked together via telephcne lines to communicate with other com puters computer based bulletin boards and larger community data base com x CA LEM EMI i m P d h r E lo by Tom Williams for home computers Networks the next step Regular Computers Editor Norm Meyers is on temporary foreign assignment For this issue we asked computer authority Tom Williams to fill in A SIMPLE NETWORK CONFIGURATION USER 5 TERMINAL OPTIONAL TELEPHONE CO COMPUTER MESSAGE COMPUTER ADAPTERS TELEPHONE LINE Here is a simplified two station network set up While the phone company adapters are optional equipment from some phone companies others insist that they be used to insure proper input matching They also serve to inform the phone company that your line to the central switcher must be of uniform data transmission quality Some phone lines aren t puters A few of these Personal Com puter NETworks PCNETs are al ready in operation and we will discuss them shortly Basically what the personal com puter needs in order to link up with a network is an interface to the telephone system known as a modem modulator demodulator There are already two such products available on the market one from D C Hayes Associate
66. vow re interested in learning how to fix air conditioners service cars or install heating systems talk to some other school But if vow re serious about electronics come to CIE The Electronics Specialists Special Projects Director Cleveland Institute of Electronics y father always told me that there were certain advan tages to putting all your eggs in one basket John he said learn to do one important thing better than anyone else and you ll always be in demand I believe he was right Today is the age of specialization And I think that s a very good thing Consider doctors You wouldn t expect your family doctor to perform open heart surgery or your dentist to set a broken bone either Would you For these things vou d want a specialist And you d trust him Bc cause you d know if he weren t any good he d be out of business Why trust your education and career future to anything less than a L e specialist You shouldn t And you certainly don t have to FACT CIE is the largest inde pendent home study school in the world that specializes exclusively in clectronics We have to be good at it because we put all our eggs one basket clectronics Ifwe hadn t done a good job we d have closed our doors long ago Specialists aren t for everyone Pll tell it to you straight If vou think elcctronics would make a nice hobby check with other schools But if you think y
67. we built in a separate coaxial cone with its own magnet and 4 layer voice coil And for brilliant high frequencies we added a piezoelectric tweeter with solid state reliability simplicity and freedom from distortion The result True hi fi quality in a system handling up to 60 watts RMS yet efficient enough for moderate power amplifiers Manufactured by Radio Shack in ovr own Fort Worth factory Ask for 40 1256 and drive illthunderous bargain at 49 95 each Retail prices may vary at individual stores and dealer Heavy duty acoustically transparent grill included Installing my Realistic speakers was easy all mounting hardware and instructions were included Another Great Value Our High Power Two Way Speaker Same great looks and powe capacity but with a dynamicay e tweeter at 10 00 less 40 125 Just 39 95 ezch FREE 79 Catalog See what s really new in electronics TEES Bigger and more colorful than ever 176 pages over 2000 exclusive items wlt Sold Only Where You See This Sign Radio A Division of Tandy Corporation Fort Worth Texas 76102 ONE Auto FM Signal Booster to eliminate Signal fading Compliments Any Dash Board List Price 24 95 Write for catalog 20 803 Dept 46 THE FINNEY COMPANY 34 West Interstate Street Bedford Ohio 44146 CIRCLE 12 ON READER SERVICE COUPON ADVANCED
68. will dis cover the station s frequency No longer need you wonder which is the most popular police fire or public service frequency the Bearcat will keep a running total of transmissions on each channel And if all this isn t enough the Bearcat can also scan a range of frequencies and electronically log each frequency used without stopping for the transmissions individually program a delay or lockout for any channel and even program automatic recorder con trol for specific channels For example if you are interested in recording only the activity on say channel 14 you can program the receiver so a re corder starts only when a channel 14 signal is received no other frequencies will be recorded If you are interested in recording what s happening on mul tiple channels say Nos 1 3 5 18 and 22 you can likewise program the re corder to start only when signals are received on any of these How is all this magic accomp lished Through use of an on board microprocessor microcomputer that provides even more heretofore un imagined performance But before we get too far ahead of ourselves let s go back to the beginning and take a look at the big picture The Bearcat 250 is housed in a cabi net measuring 1034 wide by 31 in high by 8 in deep It will operate off 120 VAC or 13 8 VDC Though it covers five bands 32 50 MHz 146 148 MHz 148 174 MHz 420 470 MHz and 470 0125 512 0125 MHz the tuner sec
69. works from the fact that every FM broadcast station generates subcarriers that can also be used for broadcasting General ly they are used to broadcast back ground music for dentist s offices super markets and the like The idea is to use one such subcarrier to broadcast digital information which can then be received demodulated and fed into the computer The receiver it is estimated can be marketed for between fifty and one hundred dollars This does not include the cost of the computer or the soft ware The receiver is in effect an input device attached to port of the com puter The real sophistication will come in the material people choose to send and receive and most importantly in the software they write to receive ma nipulate scan catalogue search and record the information presented In digital broadcasting it is once again the string handling capability of the computer that is decisive The basic function of the system will be for the user to enter a list of keywords strings into the computer corresponding to sub jects he would like information about The computer inputs the broadcast in formation into an input buffer and com pares it with the keyword list If the text contains one of the keywords any where in it it is transferred to an output Continued on page 94 ELEMENTARY ELECTRONICS January February 1979 Learn to speak to your computer while having the time of your life By N
70. 0 volts is fed into the 6 500 turn winding of the transformer 5 Can a transformer be used with DC Why 6 What will be the phase relationship between the voltage across the primary of a transformer and the voltage across the secondary assuming the coils are wound in the same direction 7 1 there is no load between the terminals of the secondary of a transformer will current flow in the secondary 8 Will there be a magnetic field produced by current in the secondary 9 Will there be a magnetic field produced by current in the primary 10 What effect will this magnetic field have on the impedance of the primary circuit 11 1f the magnetic field were weaker would more less current flow in the primary circuit ANSWERS 1 __ 1 000 _ pe 6 500 m 1 to 6 5 2 Ed 6 5 E 6 5 85 x 6 5 552 5 volts 3 If you reverse the leads the turns ratio is N 6500 E N 1 000 E The output would be E 1000 85 x 0 153 13 volts approx 4 The voltage appearing at the 1 000 turn winding will be 1 000 m 6 500 x 130 20 volts 5 A transformer cannot be used with direct Current A direct current in the primary does not produce a pulsating magnetic field The voltage across the secondary will be 180 out of phase with the voltage across the primary o 7 No current will flow 8 If no current flows no magnetic field will be pro duced by the seconda
71. 0000 was Of what use is a child v 14A Ww x S 2 tor 51 a 5725 med 855025 E SERIES PECIA 1 E e WI UR te s Delta has a iot of SERIES SN74XX ICs plus a few lineara which aa G E HORIZON LINE y were removed from wire wrap boards Included are juat about every SN74XX in the book plus amps phase lacked lt S etc and others found in a DHE a Only defect is pins bent when removed from board We are selling x these in lots of 125 which will include a good cross section of the mixture Money hack guarantee if not 100 satisfied No choices at thie price bui vou will get a goad working supply of these useful devices 45915 125 set SN74XX amp linears ITAUT BAND METER Model 251 50 micraamp movement 2 Scales 20 0 100 and 0 3 2 mtg hole Shielded movement Distributor s price 31 80 our spectacular price less than 25 Deka No 5643S Enclose sufficient postage Excess refunded Hey Look Me Over Continued from page 13 3 for 25 OSD OOOO Ooo sound applications where exceptionally good music response is required The Model 2831 is designed to reproduce a broad frequency response spectrum 50 Hz 15 000 Hz and will accept 30 watts 68S OSS ELEN L LELLI OS OSs SS SA Ses When in our area North eastern Massachusetts or Southern New Hampshire visit our new showr om loaded with many desirable Item
72. 001 Practical Electronic Circuits 12 95 966 272 p The Complete Handbook Public Address Sound Systems 10 95 ffi L Facts About Club Membership The 4 introductory books of your choice carry publisher s retail prices of up ta 65 80 They are yours for only 49 each plus postage handiing with your Trial Membership You will receive the Club News describing the current Selec tion Alternates and other booky every 4 weeks 13x a year If you want the Selection do nothing it will be sent to you automatically If you do not wish to receive the Selection or if you want to order one of the many Alternates offered you simply give instructions ow the reply form and in the envelope provided and retum it tn us by the date specified This date allows you at least 10 days in which to return the torm If because of late mail delivery you do not have 10 days to make a decision and so receive an unwanted Selection you may return it at Club ex pense To complete your Trial Membership vau need buy only four additional monthly Selections or Alternates during the next 12 months You may cancel your Membership anytime after you purchase these four books All booxs including the Introductory Offer are fully return able after 1 days if you re not completely satisfied All books are offered at low Member prices plus a small postage and handling charge Continuing Bonus If you continue
73. 3 21er 1 00 41or 1 01 FND 10 BLOCK READOUT 122 com cathode 2082 21or 1 19 4for 1 20 amp DIGIT READOUT led com cethode rad E 190 1 for 1 98 21or 1 96 dd O FND 503 5 red com cathodes T 29481 5 accus sold 1 50 21or 1 51 9 FNO 500 t red com anode 7 sag 2950 Doe ME 1 50 21or 1 51 E D FND 800 B8 red common anode e 3 95 21or 3 96 x O FND 803 8 rad common cathode 339 T EEN 3 95 2 for 3 96 AMPLIFIERS Each 2 tor WATTS ON A CHIP Toshibs 7205 5057 4 95 4 06 D WATTS ON A CHIP G E 263 7 1522 1 50 1 51 4 10 WATT STEREO AMPLIFIER PA hi fl mobile 12V 8324 5 88 2 for 9 89 IC SOCKETS TIE Py N 4 TYPE O 8 PiN MINI DIP 2123 4 fer 1 19 8 tor 1 20 CONDENSER MI D 14 DIP 1308 1 109 1 20 D 16 DIP 1309 1 19 1 20 4 95 2 fo 18 DIP 7 3378 49 1210 1 20 r 96 24 PIN MSI DIP 3886 2for 1 19 4tor 1 20 a a tittie D 28 PIN MSI DIP 3887 Zfor 1 19 4for 1 20 quality 4 sound H BCS DIP SWITCHES rel ere Each 2 tor respon rd eque d 2 SWITCHES ON A DIP 3668 77 78 f pin or tape 30 000 Hz Eney J 3 SWITCHES OIP 3649 88 IL dance
74. 302 Although it is rec ommended that the Laser Lite be used in conjunction with ordinary bicycle lights it is not strictly necessary Says the manufacturer ELEMENTARY ELECTRONICS January February 1979 Some short insights into the world of antique radio HELLO OUT THERE IN RADIOLAND I often read the Books for sale col umns in the antique collector s news papers I subscribe to Recently I found a book about the life of a rather unique character from the early days of radio Norman Baker If your memory is good you may remember that Norman Baker manufactured the Tangley Air Calliope which was also called the Cal liaphone It was a musical instrument operated by compressed air rather than steam which made it much safer for the operators of the calliope Baker was also the founder of radio station KTNT in Muscatine IA Because of his claims of curing many victims of cancer he became involved in disputes with the AMA and later with the FCC which led to the loss of his sta tion license in Iowa He then went to Mexico and estab lished radio station XENT This sta tion was one of the most popular and powerful in North America The book makes fascinating reading for the ra dio collector who is interested in the history of the 1930 s Phonograph Museum I attended IHRS meeting held at the Midwest Phonograph Museum located on In idana 252 just off Indiana 37 near Martinsville IN The museum wa
75. 4164 79 90 D 7416 99 1 00 C 474168 1 99 2 09 N74173 99 1 00 D 874175 99 1 00 D 874177 80 D N74179 1 99 2 00 D 474190 49 50 1 9 741892 49 50 D N74190 1 99 2 00 9974191 1 78 1 76 N74192 08 86 C N74193 99 1 00 174194 1 25 1 26 C SN74197 7 7 474198 1 50 1 51 N74200 3 50 3 51 5 74251 79 80 N74284 3 99 6 00 D N74298 3 75 3 76 1 103 5 N bl Type Each 2 for C LM709H 19 20 C LM709N 49 50 D LM723N 49 50 O LM733N 79 50 O LM 741H 30 31 O LM747H 59 60 O LM1304 1 49 1 50 O LM1310 1 79 1 80 O LM1312 2 49 2 50 O LM1414V 19 20 O LM1458V 39 40 C LM1800N 79 C LM3028H 65 56 D LM3900R 49 50 O LM3909V 1 25 1 26 LM4250 1 20 121 O LM75451 69 70 D LM75453 69 20 O LM75491 80 81 O LM75492 80 81 O LM75494 60 51 50 29 Order by Cet No WATTS Sale D 6 V 3tor O 82V 3 tor D 15 V 3 tor 18 V 3 tor Q 24 V 3tor D 30 V 3 tor Why buy by store CIRCLE 20 ON READER SERVICE COUPON L NFLATION REVOLT WE RE FIGHTING BACK INFLATION WITH THIS EXCLUSIVE 1 SALE BUY 1 AT SALE PRICE GET 2ND FOR IC MORE anaogogoaogoepaaaocaaaaogaoeaoaoogaoaaoogaaonooanogongngo turns Why are these metic functions 4 ARE rejects Mantly keyhoard memory functions Dno WORTH prablems we are told Hut ul cent equals clear i E these priren wh care wl Vest units complete and n MOR pocket si
76. 4LS181 250 7415266 39 7415377 1 50 7445055 19 74555 19 745133 29 7415183 3 50 7415273 165 7415378 1 25 74LS08 19 74LS63 1 50 7445136 39 7445199 89 7415275 450 7415379 1 35 74LS09 19 74LS73 29 745138 64 7418191 89 7418279 59 74LS386 49 74LS10 15 744574 35 745139 64 7405192 95 7415280 1 75 745390 1 50 740511 19 74575 49 7405145 99 7415193 95 7405283 85 7415393 125 74512 19 741576 39 7415147 7405194 75 7405290 85 7415395 1 50 740513 35 741578 39 7415148 99 7405195 66 7405293 1 10 7415396 170 741514 59 744583 79 74LS151 59 74LS196 1 09 74LS295 1 25 74LS398 265 Dual In line Soc kets PLUGGABLE SOCKET FOR IC PACKAGES l HIGH RELIABILITY GAS TIGHT JOINT Finest Quality FULLY QUALIFIED TO MH S 8374 Sockets Available COMPACT LOW PROFILE DESIGN NO WICKING WHEN SOLDERED TO Anywhere PC BO ARD FLAMMABILITY RATING UL 940V 0 Stock level Contacts 14000 8 PIN 11 345000 14 PIN 156000 16 PIN 33000 18 PIN e 74LS15 19 74585 99 745153 59 7415197 1 09 7415298 1 25 7415399 1 50 18000 22 PIN 740520 15 74LS86 35 74LS155 99 7415221 1 25 7415299 295 7415424 4 50 84000 24 PIN 74LS21 19 74LS90 59 74LS156 80 74LS240 1 95 74LS324 1 25 74LS445 1 25 25000 28 PIN 740522 19 74591 99 7415157 59 7415241 195 74LS325 255 7415447 125 740526 25 74LS92 59 745158 69 74LS242 195 7415326 255 745490 1 95 46000 40 PIN 740527 21 744593 49 745160 84 7415243 195 7415327 255 7405668 90 74LS28 21 7445955 70 7415161 84
77. 5 Hand book 18 D fferent 50e 20 Different 50 Catalog 50 Laboratories 1477 G Gaiden Grove CA 92642 SAVE 50 build your own speaker system Write cQee Radio E ectronics 1901 McGee Street Kansas MO 84108 CONSUMER TV REPAIR PROTECTION GUIDE 35 fact filied chapters Non technical language Save service cails Reduce anxiety about radiation burn ing sets Lghtniig damage picture tube failure New protection for Lghtning When to repair or buy Detailed illustrated major amp minor repair symptoms and defects Installing antennas illustiated Who to call TV man or antenna man Consumer questions and answers 33 years experience Copyrights Com plete Guide 8 95 Postpaid Send check or Money Order No COD GENES COLOR TV 79 West St Lunenburg MA 01462 amp VERY Interesting Next 5 issues 2 Electronics Trader Folly Beach SC 29439 LINEAR Ampilfiers 3 5 30 MHZ Schematics De talled Instructions For Base BL 200 Mobils BL 100 and BL 200 All 6 00 Bomar s Box 541 Pendleton SC 29670 RUBBER STAMPS RUBBER stamps made Three lines 3 75 Rubber Stamps B1337 E9 Waldo AR 71770 SCIENCE amp CHEMISTRY FIREWORKS Spectacular novelties Simplified manufacturers textbook 5 00 Tropic Box 95M Palm Bay FL 32905 SONGWRITERS SONGWRITERS Exciting offer poems songs need ed Free evaluation Creative Music Productions Box 1943 A11 Houston TX 71001
78. 75 kHz IF transformer coils were modified to provide low frequency coils for receiv ers I tried this with a friend but Chi cago distribution lines were not direct routes so we only had very short range communication The photographs are those of a 1950 carrier current receiver built by Westinghouse National dials labeled Primary and Second tuning and coupling help create the feeling that you are looking at old home made amateur radio equipment The empty tube socket on the upper right of the panel is for a 6L6 detector tube This detector could operate telemetering de vices directly or operate headphones without further amplification The other empty socket is for a neon lamp across incoming signal lines to prevent over loading the receiver The rear view shows the nice Card well tuning condensers plus the ro tating tuning coil on the variable cou pling control Another form of C C radio is the wireless intercoms adver tised in most radio catalogs This de vice consists of an oscillator modulat ed by a voice frequency The house wiring carries the signal At a recent IHRS auction sale a CC transmitter and receiver sold for a very low price considering all the nice parts and tubes that were in it I guess I must have been asleep when it was sold Crystal Receivers There is another new book out about crystal radio re ceivers The book is titled The Cat s Whisker by Jonathan Hill The b
79. 807 2 Returns from news agents 67 595 G Total 280 254 The actual number of copies of single issue published nearest to filing date A Total number of copies printed 288 645 B Paid Circulation 1 Sales through dealers and carriers street vendors and counter sales 39 000 2 Mail subscriptions 190 182 C Total paid circulation 229 182 D Free distribu tion by mail carrier or other means samples com plimentary and other free copies 1 200 E Total distribution 230 382 F Copies not distributed 1 Office use left over unaccounted spoiled after printing 825 2 Returns from news agents 57 438 G Total 288 645 certify that the statements made by me above are correct and complete signed V C Stabile Vice President and Treasurer For completton by publishers mailing at the regu lar rates Section 132 121 Postal Service Manual 39 U S C 3626 provides in pertinent part No per son who would have been entitled to mail matter under former section 4359 of this title shall mai such mat ter at the rates provided under this subsection unless he files annually with the Postal Service a written request for permission to mail matter at such rates In accordance with the provisions of this statute hereby request permission to mail the publication named in item 1 at the reduced postage rates pres ently authorized by 39 U S C 3626 signed V C Stabile Vice President and Treasurer I
80. 8220 138 300NS Part No 1000 8238 4 75 sll at am Ne Leer UART s 4900 8251 588495 1N4148 100 4 5 027 Stock level Part No Price 500 8253 14 95 5200 8255 5 95 290000 AY5 1013A 4 95 1100 8257 995 __ 9200 AY3 1015 5 95 77 7905 1K CMOS RAM 1500 6810 3953 50 1700 6820 4953 95 Stock level Part No Price 1400 6821 2043 95 2800 6850 5954 95 4400 ome Ol 4 95 700 6852 596 4 95 Z80 CPU 280 510 0 59 00 Z80A CPU Z80A SIO O 68 00 common TX amp RX clocks ZBOPIO with OTRB Z80A PIO d Z80 CTC 10 1 59 00 780 280 510 1 68 00 separate TX amp RX clocks without DTRB P O BOX 1035 FRAMINGHAM MASSACHUSETTS 01701 MINIMUM ORDER 10 00 ADD 2 00 TO Over the counter sales COVER POSTAGE amp HANDLING Canadian 12 Mercer Rd Natick Mass 01760 customers add 30 for exchange and handling All Behind Zayres on Rte 9 federal and provincial taxes extra Telephone Orders amp Enquires 617 879 0077 Foreign customers please remil payment on an IN CANADA 3 LOCATIONS international Dank draft or international postal money Order in American dollars 5651 FERRIER ST 4800 DUFFERIN ST BAXTER CENTRE MONTREAL QUEBEC OOWNSVIEW ONTARIO 1050 BAXTER ROAD HAP 2K5 M3H 5S9 OTTAWA ONTARIO Tel 514 735 6425 Tel 416 661 1115 2 3 2 Tel 613 820 9471 CIRCLE 39 ON READER SERVICE COUPON Bookmark Continued from page 14 Register Co Inc this textbook combines explana
81. ARN Computer Programming BASIC or FOR TRAN Electronics FCC License Mathematics through correspondence study Free information In termountain Technical Institute Room 13 Box 258 Jerome ID 83338 LES PLACE Classified To be included in the next issue pelase send order and remittance to R Wayner ELECTRICAL EQUIPMENT amp SUPPLIES Cont d LIGHT Triggered IC Relay Driver 6 VDC Adjust able Threshold All Assembled only 3 00 302AT Sonic Switch turns on Lamps Motors etc Com pletely Assembled Solid State Super Buy only 3 00 210AT 3 Transistor Audio Preamp for Mike Phono Tape etc Hi Q input 8 45 Ohm output 3 VDC Completely Assembled Only 4 00 AT032 ABT Systems 113 Schereville IN 46375 TRS 80 SOFTWARE Level I BASIC 4K ROM Free FH Curley Services 156 Rochester MN 55901 EMPLOYMENT INFORMATION AUSTRALIA New Zealand want you Big pay All occupations Reports 2 00 AUSTCO Box 8489 EE Long Beach CA 90808 FOR THE HOME PRACTICAL tips for home garden and workshop can be found in 1001 How To Ideas Send 1 50 for your copy includes postage to 1001 How To Ideas 386 Lexington Ave New York NY 10017 BUDGET Reclpes SASE 1 00 Churchco Distribu tors 625 St Clair St Box 5 Chatham Cntario Canada NTL 3L3 FRANCHISE OPPORTUNITIES 20009 profit selling information by mail free de b International 1 Ta
82. Circuit Operation The HEP C6049R is actually a DC regulator within a regulator which accounts for its high performance As shown in the block diagram a very stable reference voltage Vr is applied to the non inverting or voltage follower input of an op amp which serves as the first regulator and DC level shift amplifier The output voltage of this stage can be varied from H ERES A LOW COST precision regul The AC line switch current jacks and cur rent meter switch are on the end of the case the regulated IC Power Supply by Adolph A Mangieri MINI REG m 3 MINI REG VOLTAGE 3 4 volts to 15 volts by varying pot R11 This voltage is applied to the non inverting input of the second op amp which is capable of supplying up to 5000 milliamperes current to the load This stage has unity voltage gain where in V out follows the input voltage to this stage This double regulator ar rangement fully isolates the DC level shift amplifier and results in very close regulation Capacitor C4 provides fre quency compensation and precludes possible circuit oscillation External components consisting of transistor QI and selectable resistor Rsc provide constant current limiting should the supply be short circuited When the load current passing through Rsc be comes sufficiently high the base of 1 becomes forward biased causing Q1 t conduct When QI conducts the voit age regulator delivers
83. Connect a milliammeter and 100 ohm resistor in series from V in plus to board pin A Set S3 to pick up R10 and set R11 to minimum resistance Turn S1 on and observe about five milliamperes current on the milliammeter and 3 4 volts on meter 1 Advance R11 and observe a voltage increase up to fifteen volts 44 Internal view of the Mini Reg The circuit board is positioned so that it doesn t come in contact with the meter and transformer The case is perforated for ventilation You can see the tiny square HEP 176 rectifier on the small circuit board in the bottom of the case In front of it is R1 C5 and the 2500uF capacitor C8 DC If the output voltage is less than fifteen volts the value of RII may be too small or R2 may be too large Hav ing verified the above you may now install the wire from V in plus to PC board pin A Plug the milliammeter into jacks J and J2 and open S2 Meter In Adjust RII for ten volts output and set 53 to ten milliamperes current limit Then connect a 3500 ohm 2 watt resistor across the output terminals If current limiting action is taking place the milli ammeter should indicate roughly ten milliamperes and the output voltage should drop to about five volts If much higher values are observed current limiting is not taking place Look for a Bias Ref D C Level Shift Vr 3 4v o gt us This is a simplified block diagram of the C6049R regulator chip the heart of the Mi
84. E TITLE Master Course in TV Audio Master Course in Color TV Electronics Technology and Advanced Troubleshooting amp Il terms available TV SET NRI designed for learning Heathkit GR 2001 25 Zenith model G4020W 19 kit Dual speaker 25 diagonal color TV diagonal color TV fully diagonal color TV cabinet extra assembled with cabinet and Video System Servicing Servicing Heathkit 10 4541 5 8 x 10 cm triggered sweep Heathkit 10 4541 5 8 x 10 cm triggered sweep not given until after graduation COLOR BAR NRI designed for learning Elenco SG 200 kit Elenco SG 200 fully GENERATOR kit 10 patterns 10 patterns assembled 10 patterns FREQUENCY NRI designed for learning COUNTER kit Complimentary metal oxide semiconductor digital type NRI designed for learning Heathkit part of TV kit kit Transistorized AC DC DC only IK Ohm volt volt ohm meter AUDIO NRI designed for learning Private label pocket transis kit Four channel high tor AM radio kit and AM fidelity AM FM tuner with FM SW solid state portable speakers radio kit NRI Discovery Lab Breadboard Experimental Electronics Lab OSCILLOSCOPE NRI designed for learning kit 5 8x 10 cm triggered sweep Private label multimeter MISCELLANEOUS EICO Digital Logic Probe EQUIPMENT All data as shown in each school s catalog as of September 1 1978 One Million Students Over 60
85. EARBOOK 1979 is jam packed with CB transceiver test reports and just about anything else a CBer could want to know Pick one up at your local news stand 78 e e checks out EMERGENC MULTICORE CIRCLE 86 ON READER SERVICE COUPON Make quick clean solder joints with a flick of your BIC C How MANY TIMES have you made an electrical repair with twisted wire connections and tape when you knew deep down in your heart that you should have used solder Sure you know the correct way to fix things first clean off the parts tin the parts and apply heat and solder That s not so hard What is hard is going down to the basement when you re making one lousy repair in the attic or connecting mile after mile of extension cord so you can climb on the roof to solder an antenna wire or an important wire on your car lets go when you re in the middle of nowhere that is what s hard about soldering When you were young and didnt know better you probably tried the old match and solder trick and learned all the fine points of why it didn t work So like the rest of us you make a lot of twisted wire and tape repairs and justify your actions by calling it field ex pediency Fire Up Now thanks to Multicore Solder a British Industries Company B 1 C there is a new type of solder that will make the old match and solder trick work like a charm Emer gency Multicore Solder is designed to do everythi
86. For these examples the initial beat or downbeat is louder than the others to identify the beginning of the rhythmic pattern but this is not mandatory In fact none of the pots needs to be set exactly as shown so feel free to do your own thing Example 1 is a simple waltz rhythm with three beats Loup soft soft Set SEQUENCE LENGTH to 3 pot 1 fully on clockwise pots 2 and 3 about halfway up as shown Tempo Volume and Light may be set as desired In a similar way you can set up rhythms of 2 4 5 6 etc beats with the first beat emphasized Example 2 a dotted rhythm has two notes of unequal duration the first dotted eighth is three times as long as the second sixteenth The short est time unit in the pattern is a six teenth and the total length of the pat tern is four times this 2 8 or 4 16 Consequently Sequence Length should be set to 4 Pot 1 should be fully on pot 4 about halfway pots 2 and 3 fully off For this rhythm clicks 2 and 3 are deleted As illustrated by this example a rule of thumb is that the Sequence Length setting should equal the total length of the pattern divided by the shortest time unit Example 3 begins with a triplet whose note each have a time value of 1 12 the total pattern has a time value 3 4 or 9 12 Thus a Sequence Length of 9 is used Example 4 is a common rhythm and is a straightforward set up on the Synthesizer Example 5 is an unev
87. Gordon Sell _ CASSETTE TAPE DECKS have come a long way towards meeting the needs of the audiophile in the past few years Considering that the cassette tape for mat was originally designed for use in car units and portables it is amazing how fast it has been adapted to high fidelity recording While few tape units can match the dynamic range and fre quency response of a good turntable and cartridge combination their ability to record material live off the air or to copy other tapes and records makes them invaluable to the hi fi enthusiast The boom in car stereo systems has also given the home cassette deck a boost in popularity since you can play your favorite cuts both at home and away from home If you are reading this magazine your interest in electron ics Obviously includes more than just hi fi you can use a cassette for re cording shortwave catches hard to copy code or perhaps even wire it up to your computer If you want this kind of versatility in your home you might find these two new cassette decks of interest Pioneer CT F 900 Cassette Deck Featuring microprocessor control and outstanding performance this set is a great buy at 475 It not only works impressively but it looks clean and businesslike with lots of switches knobs push buttons and flashing LEDs It features adjustable bias that allows you to fine tune the deck to the char acteristics of the type of tape you use plus a manual switch for stand
88. Guaranteed 589 Danshee Enterprises 73 Oak St Closter 01624 P C BOARDS your artwork No setup charge 45 sq in single sided 60 sq in double sided Ohio residents add 4 5 sales tax Digitronics P O Box 2494 Toledo Ohio 43606 GREETING Cards Custom made for any occasion Paul Reich Productions Box 384 Peconic NY 11958 AWARD Medals enameled pins Made from your design Very inexpensive when ordered by the hun QUIM Enameled Pins P O Box 322 La Mesa PRINTED Circuit Boards From Sketch or Artwork re Details DANOCINTHS Box 261 Westland MI 185 MONEYMAKING OPPORTUNITIES 250 00 profit thousand possible stufilng mailing envelopes Offer Rush stamped addressed envelope Universal ADVS X16180 Fort Lauderdale FI 33318 FANTASTIC Profits Mailing Circulars Free Samples Grahamco DPBX 99371 Tacoma WA 98499 180 00 WEEKLY Mailing Circulars Start im Alera Everready 422A Clermont Ave Brooklyn Y 11238 MAKE YOUR CLASSIFIED AD PAY Get How to Write A Classified Ad That Pulls Includes certif cate worth 2 00 towards a classified ad in this publi cation Send 1 50 plus 25 for postage to R S Wayner Davis Publications Dept CL 380 Lexington Ave New York NY 10017 WIN thousands Thoroughbred Harness Dog Free report Finish A Box 6226 Toledo 43614 83 501 00 FREEBIES WAITING GOVERNMENT buf 3 00 PALMER B1244DG Phenix City 300 00 WEEK
89. Hz another non stop station La Voz de la Selva HJKF Floren cia 6 170 kHz the name stems from another of Colombia s climatic con trasts the Voice of the Jungle There you have 14 shortwave out lets that you can hear but only part of the Colombian listening targets for DX ers ANARC 1978 The Association of North America Radio Clubs ANARC is the umbrella organization linking the various major radio listening hob by clubs in the U S and Canada Each year ANARC holds a convention in the summer in some major city in the United States or Canada where listen ing hobbyists can get together ANARC 778 hosted by Radio Can ada International for four days last July was the most successful such gath ering in the 14 year history of the as sociation Hobby listeners came to Montreal from across the continent from California to New Brunswick ELEMENTARY ELECTRONICS January February 1979 and fronr as far south as Trinidad In addition the world of broadcasting was represented by Arne Skoog of Radio Sweden Ambrosio Wong of Radio TV Espana in Madrid and Paul Modic of the Voice of America plus RCT s host Ian McFarland The convention program included tours of the RCI facilities and live demonstrations of the Canadian ex perimental HERMES satellite to home TV broadcasting There were DX ing workshops conducted by a variety of experts in various broadcasting and listening areas Dr David Meisel spoke
90. I didn t expect it too The first thing to do is to remove the knobs dial escutcheon the back if it has one and remove the chassis from the cabinet The speaker may be fastened to the front panel or it may be chassis mounted Remove the chas sis Spcaker and any other item that may be attached to the cabinet In This is how the radio looked be ore restor ation It is in quite good condition and the veneer is intact If the radio you want to restore is badly dam aged and the case is broken you might con sult a book on restor ing antique furniture for repair techniques ELEMENTARY ELECTRONICS January February 1979 The chassis was in surprisingly good shape and all 1 had to do was replace the cracked line cord a filter capacitor and all of the tubular capacitors see text for details spect the speaker grill cloth and if it is so badly damaged that it will spoil the appearance of the restored radio throw it away Set the chassis aside and re store the cabinet first This is how the chassis looks now that the repairs and replacements have been made Get out all the old spiderwebs and dust Give the tubes a good wash make sure they are dry before you fire up the old rig Scrub It Down The cabinet should first be washed with a damp cloth and a mild detergent Do not soak the cabinet just scrub it and rinse it You will be surprised at the improvement TRIAL RUN PROTECTION CIRCUIT PL
91. ING COST of test equip ment it is advantageous to be able to perform several operations with one meter For instance a DC milliammeter can be converted to read higher values of current by adding a shunt to bypass the bulk of the current around the deli cate meter By following a few simple steps a milliammeter can be converted to read 10 to 20 amps or more The first step is to determine the internal re sistance of the meter From this you can calculate the shunt resistance need ed and the type of material to be used To find the internal resistance of the meter construct the test circuit illus trated here The 4700 ohm resistor is used to limit current and serves no oth er purpose Start with the power sup ply set to zero volts leaving S2 open and S1 closed Slowly increase the cur rent flow by varying R3 until the meter needle moves to full scale deflection Without touching the setting of R3 close S2 and adjust R2 until the meter reads half of full scale According to Ohm s Law the resistance of the meter and of R2 are now equal Open switch S2 and measure the resistance across R2 This value will be equal to the internal resistance of the meter Shunt Precise shunt resistance is im portant for accurate current readings and must be chosen carefully With the shunt connected across the meter most of the current is diverted past the me ter This is the theory behind a small meter being able to read high currents The shunt
92. ING OFFERS Catalog price 1 00 completely rhythms Look for it around 0430 to 0530 or so 9 435 Israel s IBA should be an easy catch for even the most inexperienced SWL Between 2230 and 2300 look for the news in English editorials and the Israel Hit Parade 11 678 Here s a station that a lot of listeners are looking for Radio Pakistan Music typical of the subcontinent of Asia should be the tip off around 2145 Credits Claud J Ethen OR Jo sephine Bryan CA Robert Foxworth NY Aaron Hywarren Manitoba Can ada North American SW Association Box 13 Liberty IN 47353 refunded with first order satisfied return them and your money e You can deduct 1096 from total price if will be promptly refunded ETTR BOAT BUILDER Craft Print Division Davis Publications Inc Dept EE 79 229 Park Avenue S New York N Y 10003 Please send copy ies of the Craft Print Catalog for only 1 00 each COM PLETELY REFUNDED WITH FIRST ORDER e ADDRESS STATE ZIP 2 or more sets of plans are ordered lf you can t afford it make it yourself Get Top Mileage from your own craft skills GREAT EASY TO BUILD PLANS ONLY 1 00 E DeVry institutes of Technology Atlanta Georgia Chicago Illinois Dallas Texas Phoenix Arizona Toronto Ontario Canada Ohio Institute of Technology Colum
93. LE 76 ON READER SERVICE COUPON transmissions without the need of direct hookup Frequency measurements are accomplished by means of its pickup antenna The Count 500 is crystal con trolled offering high accuracy over its entire operating frequency range Dis plays frequencies from 3 to 500 MHz without the need of any expensive add on devices Designed for portable use may be used for either base use with AC power pack supplied with the Count 500 or as a mobile unit with the Telco Optional DC cable with auto lighter plug connector Suggested retail price is 184 00 For additiona information write to Telco Products Corporation 44 Sea Cliff Avenue Glen Cove NY 11542 Bi Directional Wattmeter The new wide band Bi Directional Watt meter the IM 4190 SM 4190 assembled version is a self contained unit that CIRCLE 1 ON READER SERVICE COUPON oOppEDAODOEGCOYT measures transmitted radio power up to 300 watts and reflected power up to 30 watts Covering the 100 MHz to 1 GHz spectrum the IM 4190 according to Heath is an ideal tool for two way radio service and repair or for the amateur radio enthusiast The IM 4190 is capable of withstanding full power overloads on its lower scales without damage to the meter movement A single 9 voit battery powers the IM 4190 so it may be used portably N type coax connectors are utilized for minimal high frequency in sertion loss Adaptors for use with RF typ
94. LESSONS You will learn trouble shooting and servicing in a progressive manner You will practice repairs on the sets that you construct You will learn symptoms and causes of trouble in home portabie car radios You will learn how to use the professional Signal Tracer the unique Signal Injector and the dynamic Radio amp Electronics Tester While you are learning in this practical way you wili be able to do many a repair job for your friends and neighbors and charge fees which will far exceed the price of the Edu Kit Our Consuitation Service will heip you with any technical prob lems you may have FROM OUR MAIL BAG Ben Valerio P O Box 21 Magna Utah The Edu Kits are wonderful Here 1 am sending you the Questions and also the answers for them have been in Radio for the last Seven years but like to work with Radio Kits and like to build Radio Testing Equipment en joyed every minute 1 worked with the different kits the Signal Tracer works fine Also like to let you know that 1 feel proud of becoming a member of your Radio TV Club Robert L Shuff 1534 Monroe Ave Huntington W Va JhouEht would drop you a few tines to say that I re ceived my Edu Kit and was really amazed that such a bargain Can be had at such a low price have already started re pairing radios and phonog raphs My friends were really surprised to see me et into the swing of it so Quickly The Trouble s
95. LY Malling Circulars McGuire Box 91054 Tacoma WA 98491 Write HOW To Make Money Writing Short Paragraphs Information free Barrett Dept C21Y 8 South Michigan Chicago 60603 AMAZING NEW PROGRAM for making money Details 1 00 Der Box 53 Station Cotdes Neiges Montreal Canada H3S 254 200 WEEKLY Stuffing envelopes spare time pos Sible Details stamped self addressed envelope Mail Seem 8023 Leavenworth Rd Kansas City KS NEWEST INCOME OPPORTUNITIES 100 s 1 000 s easily FREEBIES exciting details FREE Ben Gee s 1 288 N Livingston Livingston NJ 07039 GUARANTEED big money making program Abraxas Ent P O Box 6072 Evansville IN 47712 45 000 in Three Weeks Guaranteed 1 for Info amp Handling John Davidson 5483 Holly Ridge Cama rillo CA 93010 300 WEEKLY Home Mailing Program Details Thomas Dept Di Box 11773 Charlotte NC 28220 2000 00 MONTHLY Possible Stuffing Envelopes Send Stamped Self Addressed Envelope Continental Box 3419D Mission Viejo CA 92675 EARN 100 Week at home Details 25 stamped addressed envelope D Annas Grandview Street Granite Falls NC 28630 5 ELEMENTARY ELECTRONICS 380 Lexington Ave New York N Y 10017 MONEYMAKING OPPORTUNITIES Cont d STUFF Envelopes 500 Thousand Free Detalls Cew Company 533 Wooster Road Mt Vernon Ohio 43050 EXCELLENT Second Income Without Your Home Send self addressed stamped envelope to Ben E
96. NDEX TO ADVERTISERS RS ADVERTISER PAGE 39 Activen Electronics sR es 92 21 HE DRE 21 34 Antenna Specialties 5 29 Products scot o pnr Gattis ciere 17 28 Avanti 8 ES a 1 Hn eee o EE 26 4p BEES Howell e eco sore rms 23 6 B amp FEnterprises eene 93 23 BRK PRECISION 28 CFR Associates A 26 ee ee ee som S 8 11 ME yc T ee Cv2 9 Continental Specialties Cv3 13 Delta Electronics iz 94 36 Dennio Jim amp 24 22 Digi Key T NER 1 2 ee ee n 22 30 Electronics Book Club 83 TI Om onis dite o aste ce ER 8 12 HnHey 5 Been SE cas M Gilfer 1 Meath Gos tecna Losi OT A649 35 Hobby World ees RO 12 24 International Crystal Eb Locksmithing institute pulsus 24 NMENeBE o E 25 3B Non linear AT R 12 Ce Re E VAT 18 21 nr mem 36 39 5 OK Machine amp Tool uad 15 BALA naa io MR 16 16 PercomDat E K T cae 14 20 eon T TNT 9 17 President 3 18 Progressive Edu kit 25 PUG NGS TAC Rito snes a
97. NRI Schools Or maybe McGraw Hill Continuing interest is CB Or gignen the expanding world 3939 Wisconsin Avenue of communications E SN mobile radio microwave FREE Bur CATALOG Audio Computers Instruments Kits amp Assembled Southwest Technical Products Corporation 219 W RHAPSODY SAN ANTONIO TEXAS 78216 The world of electronics aviel el Saran SPOR Gee FETE La YOURS FREE 32 pages of test instruments from the latest digital multimeters to the famous EICO scopes Security systems Auto motive and hobbyist products Kits and assembled EICO quality EICO value For FREE catalog check reader service card or send 75 for first class mail wEICO 108 New South Road 7 Hicksville N Y 11801 CIRCLE 2 ON READER SERVICE COUPON By Don JENSEN Columbia the Gem of the Ocean So goes the patriotic verse But for shortwave listeners it s Colombia with an not a u in the middle that s a gem when it comes to DXing Colombia is the linchpin of South America that ties the southern con tinent t Central America a major Latin nation washed by both the At lantic and the Pacific It is a land of contrasts humid jungles sunbaked plains lofty Andean mountains sunny sandy beaches major cities and tiny villages That contrasting nature of Colombia holds true when it comes to shortwave broadcasters There are the pop and Latin sounds
98. Pass the AC line cord through the left side of the case and knot the cord for strain relief Install resistors R6 thru R10 on switch 51 Depending on the base emitter characteristics of Q1 the specified values or current limit resistors R6 through RIO may differ somewhat in your power supply This is why trim resistor R5 was included to properly trim the 500 mA current limit For this reason you may defer installation of R6 thru R9 but do install R10 Place RECT 1 R1 C5 and C8 on a small piece of perfboard and situate this sub assembly behind the meter Connect meter M1 directly to binding posts BP and BP2 Use 20 stranded wire for connections to the PC board Connect a wire from board pin G to BP2 Run a wire from board pin E to the rotor lug of S3 Connect a wire from board pin D to resistors on S3 Run a wire from board pin F directly to 1 Run a pair of wires from pot R11 to board pins B and C Connect a wire from V in minus directly to BP2 Do not make the connection from V in plus to board pin A at this time You may omit the double fused plug and provide but one fuse in the primary side of transformer 1 Carefully check all wiring and solder connections Checking It Out We intentionally de ferred installation of several components and some wiring so that you can per form a few simple tests which preclude damage to circuit components Connect a voltmeter across 1 and verify that V in plus is nineteen volts DC
99. Pressure Unit Edmund Scientific is offering an elec tronic blood pressure gauge ideal for home use The gauge gives a reading by sight and sound and is a simple one handed operation Equipped with a Vel cro cuff it is easy to use will hold firmly for accurate readings and does not require a stethoscope It is equipped with a flashing light and audible beep for systolic and distolic readings Com plete unit includes blood pressure record charts gauge unit 9 volt battery in struction booklet and a vinyl carrying case No prior knowledge or experience is necessary Praised by physicians and bio medical engineers it completely automates the taking of blood pressure Its easy to read scale is graduated from to 300 mitlimeters of mercury The CIRCLE 56 ON READER SERVICE COUPON Electronic Blood Pressure Gauge stock no 61 188 is priced at 79 95 post paid Your electronic blood pressure gauge can be ordered by mail from Ed mund Scientific Co 7782 Edscorp Bldg Barrington NJ 08007 Hog the Channel Valor Enterprises Road Hog antennas have been completely redesigned to de liver the power and performance that big rig truckers demand like top load ing a wave and 1000 watt rating Super strong construction is built into every Road Hog by using a in fiber glass rod which is permanently bonded inside a longer chrome plated ferrule by a special adhesion process Precision wound 16 gauge insulated copper wir
100. Reversing the AC plug usu ally remedies the problem If not con nect a ground wire to either the plus or minus terminal of the Mini Reg whichever proves most effective In addition to its use as a universal AC adaptor the Mini Reg serves as an ex cellent power supply when servicing of High Fidelity help you We ve completely revised updated and expanded our popular Official Guide to High Fidelity This abundantly illustrated 207 page guide gives you a step by step approach to help you select the latest and best hi fi component system for your home Use the coupon and INSTITUTE OF HIGH FIDELITY INC send 5 50 per copy to cover cost postage and handling OFFICIAL GUDE Fiber 489 Fifth Ave New York N Y 10017 Official Guide to High Fidelity Name Address ELEMENTARY ELECTRONICS January February 1979 Have you outgrown your music system too A lot s happened in high fidelity since you bought your first music system So if you re thinking of replacing or upgrading your golden oldie with a new music system let the Institute Please send 1 ___copies of the new Enclosed is 5 50 per copy postage paid City State Zp N Y state residents add appropriate tax This is an exact scale printed circuit board pattern showing the foil side of the board This side contrary to normal is where the components are to be mounted Only the jumper and the
101. S January February 1979 by Kathi Martin KGK 3916 CB Carousel Lafayette launches a new CB classic FOR MORE YEARS than I care to remember the Lafayette marque on a CB transceiver meant the highest level of performance and the very latest in operating features Some models such as the 500 525 625 and Dyna com 23 were legends in their own time As with almost everything else how ever others caught up often surpassing Lafayette transceivers in both perform ance and features and the Lafayette brand became just another line of CB transceivers ranging from adequate to good Now Lafayette has come back with a roar and their model LM 300 40 channel AM rig leads the way with one of the best features I ve used in many a ycar a secondary channel selector One of the problems I have out here in the east is the use of two different highway channels on roads that inter sect and intertwine In my case it s channels 13 and 19 Often I m con tinuously exchanging between the super Slabs and it s a first rate pain in the arm to keep flipping back and forth between channels 13 and 19 With my new Lafayette LM 300 and its secondary channel selector the prob lem no longer exists because the rig keeps track of both channels and will lock the transmitter to the monitored channel unlike some scanning rigs that lock the transmitter to a main channel while scanning two channels If one channel comes alive
102. SUNSPOT NUMBERS JFMAMJJASONDJFMAMJJASONDJFMAMJJASOND the effect is the same Radio signals can be heard many thousands of miles away thanks to the ionosphere The highest frequency which the ionosphere can bend back to earth is called the maximum usable frequency MUF The MUF depends upon how densely ionized the various layers of the ionosphere are Ionization increases when the sun is active pumping out 1979 1981 3 1981 1980 9 979 Sunspot numbers are expected to peak out in first half of 1980 when the number should exceed 150 for the third time since 1947 Already the numbers well above normal rates ELEMENTARY ELECTRONICS January February 1979 more ultraviolet radiation and charged particles Sunspots are an excellent barometer of solar activity When the sunspot number climbs so does the MUF Sunspot numbers go through cycles which average approximately eleven years in length When sunspot numbers are low the higher shortwave frequen cies above 14 MHz are generally only useful in daytime There are often many days when such higher frequen cies are completely dead for long distance communication even in day time But during periods of high solar activity frequencies up ot 30 MHz may be useful for long distance communi cation day and night and even low powered stations can find themselves able to communicate all over the world
103. TCH EXTERNAL SPEAKER TAPE JACK GROUND VAC I3 8vDC EXTERNAL ANTENNA All connections are through rear apron connectors The power source is auto matic simply plug in the AC or DC power cord The aux switch terminals can be used to start a recorder and are specifi cally programmed for one or more chan nels as required by the user quencies in the store memory Then the antenna is connected and the search resumed Now the search literally skips over the birdie frequencies and the only signals that will be locked up during the search will be legitimate signals Of course the birdie frequen cies are entered in the 64 channel store memory and by stepping through the memory the user can get a listing of both the birdie and signal frequencies You get the listing by pressing a recall button each press steps the tun ing and display to the next frequency in store memory To let you know you have run through all the frequencies discovered through the last search run the display will blank after the last searched frequency and then repeat lowest fre quency PROGRAM OE LF The Hardware The front panel has only two controls one for volume power switch the other for squelch Somewhat unusual the squelch con trol has a detented switch position at full CCW labeled auto meaning auto matic squelch It s a factory set squelch level that appears to be just about right The rear a
104. Test instruments home entertainment units and industrial control systems are all going digital And now NTS training programs include a wider choice of solid state and digital equipment than ever before offered in any home study course Advanced NTS Heath digital color TV 25 diagonal with optional programming capability NTS Heath microcomputer digital test equipment digital stereo receiver 70 watts per channel NTS compu trainer plus much more state of the art equipment to make your training exciting and relevant The equipment you receive with NTS training programs is selected to provide you with a solid the first name background in electronic systems Kits and lessons are designed to work together to demonstrate electronic principles and applications The kit building not only shows you how electronic hardware functions but how various circuit designs accomplish different purposes Your lessons guide you through any number of experiments associated with many projects This is the Project Method and it works Step by step you learn how and why digital electronics has become a part of our world and the even bigger role it is sure to play in the future Whether you are looking for training in Consumer Commercial or Industrial electronics NTS offers fourteen courses some basic many advanced in several areas of electronics An all new full color NTS catalog shows you what each course covers AN V electronic
105. The peak level indicator calibrations are right on the mark at 0 0 dB 3 dB and 6 dB The wow and flutter meas urcs in at 0 09 percent with peaks to 0 15 percent Overall this is a very good set for the money The tape handling mecha nism 15 one of the best ever to pass through our laboratory Its easy to load and unload and a snap to keep clean If you want more information about the Sanyo RD 5350 circle num ber 68 on the reader service coupon What s New Here are a few little jems that you might like to add to your systems Just circle the appro priate number on the readers service coupon elsewhere in this issue and a brochure will be sent to you Radio Shack has a new Realistic inte grated amplifier called the SA 2001 that puts out 60 watts RMS of very clean music power for 279 95 with a wood cabinet Circle number 32 Hitachi has a new microprocessor controlled cassette deck in the works that automatically tests a tape and ad justs the bias in a whirl of flashing LEDs On the market in January for about 1 000 Circle number 46 Audio Technica has a super new phono cartridge the AT20SS with a beryllium cantilever stylus arm and Shibata tip List price 195 Circle No 65 Nakamichi has introduced an Audio Analyzer that will measure power wow and flutter speed drift total harmonic distortion and more Retails for 800 Circle No 73 TDK has a cure for magnetized cas sette heads the HD 01 head demag ne
106. UESS IS TOO SMALL OR TOO BIG REM e COMPUTER THINKS OF A NUMBER CALL IT X LET XeINTCIO8sSRND CO 0 1 EE PRINT PRINT I HAVE A NUMBER START GUESSING 406 416 428 430 REM HUMAN STARTS GUESSING PRINT PRINT WHAT IS YOUR GUESS INPUT G computer checks Quess G against its number X follow me if guess is 440 IF GsX THEN S16 Pd follow me if guess is IOOC correct follow me if 0 if guess was not right on vid not too big U S 468 PRINT TOO SMALL TRY A LARGER NUMBER H I 470 GO TO 410 R 0 489 PRINT TOO BIG TRY A SMALLER NUMBER n 498 GO TO 419 HAS GUESSED THE COMPUTER S NUMBER PRINT YOU GUESSED IT LET S P e PRINT LAY AGAIN GO TO 318 28 538 999 END 4 This flowchart and game program is reprinted with permission from People s Computer Company s book What To Do After You Hit Return or PCC s First Book of Computer Games Menlo Park CA PCC 1977 See the text for details on how use such aids ELEMENTARY ELECTRONICS January February 1979 55 Here in one place each issue of e e you will find product information on the newest hobby computers and accessories Smarts for Home Use Smarts Il is now made available to the man on the street by Firebird Sales Company The microcomputer is claimed to be a powerful business data processing sys te
107. UG RADIO IN HERE S TO WALL OUTLET 4 J COL 100 WATT C LIGHTBULB This circuit can keep your first trial run from being a disaster by protecting the radio from faulty transformer or capacitor this will make If there are grooves cut through the veneer for decoration clean them with an old tooth brush After the cabinet is clean look for scratches cigarette burns white rings left by wet glasses or other defects in the finish If there are only a few scratches these can be touched up with stain and a 41 a G ANTIQUES RESTORED small brush even iodine will cover scratches in some wood You can also find color sticks in lumber yards to match the cabinet color If you have a can of brown paste shoe polish you can touch up the cabinet and give it a wax job all at the same time If you have never tried shoe polish don t knock it You can also buy colored Simoniz wax or perhaps you know of other products There are lots of old plastic radios avail able at junk shops and flea markets through out country This was bought or 1 50 After washing cleaning and polishing the cabinet looks just like new and it will fit in with the rest of your collection that will do a good job After you touch up the scratches give the cabi net a good coat of paste wax and buff it with a soft cloth This treatment will restore many of the cabinets you find Stripping the Wood Now suppose the amage is worse than y
108. Voltage ranges are from 0 25 V ten steps DC to 1 000 and 2 5 V to 250 VAC in three steps There are four current ranges 0 50 microAmps to 50 milliAmps DC and 0 to 2 5 Amps AC Diodes testing is from 0 75 microAmps to 750 milliAmps and 0 75 milli mps to 75 milliAmps The LT 70B sells for 42 95 and is complete CIRCLE 61 ON READER SERVICE COUPON with one set of heavy duty test leads and one set of alligator clip adapters For further details contact Leader In struments Corp 151 Dupont St Plain view NY 11803 59 e e assembles the MUTT MINDER Ultrasonic canine cop keeps Fido off your case MANS BEST FRIEND isn t always as friendly and loving as we would like him to be Ol Fido can sometimes de velop nasty nipping habits and if you deliver mail or newspapers sell door to door jog or ride a bicycle through a dog infested neighborhood then Mutt Minder might be for you Mutt Minder is not a toy and it should be used with care It works by giving the attacking dog a loud blast of ultrasonic sound Most humans can t hear it although according to the man _ ufacturer it can be irritating to some children and young women whose ears are most sensitive to high frequencies Above all keep it away from eyes and ears and do not let children play with it The manufacturer s instruction sheet says Use common sense as the device could be classified as an infernal ma chine requiring spe
109. XICAN GIRLSI Friendship mar riage Photos information Free Latins Box 1716 Chula Vista CA 92012 PERSONALIZED BIORHYTHMS Three month printout only 1 00 Send birthdate Brian Peterson Box 231 E Northfield Minnesota 55057 p JAPANESE introductions Girls photographs de scriptions brochure details 1 00 INTER PACIFIC Box 304 SC Birmingham MI 48012 DO YOU KNOW How to Write a Classified Ad That Pulls includes a certificate worth 2 00 toward amp classified ad in any of our publications For your copy send 1 50 plus 25 for postage to R 5 Wayner Davis Publications Inc Dept CL 380 Lex ington Ave New York NY 10017 LONELY LOVELY LADIES 200 names photos addresses descriptions 16 page illustrated magazine only 3 Hurry Write Merit Box 74758 C Los Angeles California 90004 RADIO amp TELEVISION TV TUBES 36 each Send for Free 48 page color catalog Cornell 4217 W University San Diego Cal ifornia 92105 LINEAR AMPLIFIERS 25 100 watt solid state OMNIPOLARIZED BASE ANTENNAS Portable mo bile memory 300 MHZ FREQUENCY COUNTER Constiuction plans 3 00 each 3 7 50 Specify fre quency band Kits available Free catalog PANAXIS Box 130 GIE Paradise CA 95969 TUBES Oldies latest Supplies components sche matics Catalog free Stamp appreciated Steinmetz 7519 EE Maplewood Hammond IN 46324 BUILD D stance Crystal Sets 10 plans 2
110. Years Experience So we can only tell you what NRI has to offer We ve been in education since 1914 starting as a radio school six years before commercial broadcasting was even on the scene Since then we ve kept right up with the times improving techniques adding material creating new courses to help people improve their skills and income Early on we learned to keep our lessons compact thoroughly covering a subject but not so much that students would be overwhelmed We call them bite size lessons because they re easy to digest Learn by Doing with Hands on Training And we pioneered the concept of hands on training NRI goes far beyond theory and textbooks to give our students actual bench experience and prepare them for the realities of electronic servicing Every piece of equipment in our Master Course in TV and Audio Ser vicing is designed for learning As you assemble the kits we supply you build a highest quality up to date 25 diagonal color TV a 4 channel amplifier and tuner with speakers your own oscilloscope Learn as you build with hands on training oe whe em mor ce apo c E E mec mms anp a a ae aw 7 digital frequency counter and other instruments you ll use in your course use later to earn good money zs a TV Audio technician The point is none of this equip ment is hobby kit or comm
111. ad of bending them back to earth Fortunately this effect is usually of short duration A solar flare also releases many high ly charged particles which travel away from the sun at speeds of 250 to 1000 miles per second At this rate the par ticles may take anywhere from one to four days to reach the earth The charged particles are attracted by the earth s magnetic field and enter the lonosphere at the polar regions The most spectacular effect of these charged particles is a display of the northern lights aurora borealis Users of the shortwave bands notice the ionosphere absorbing signals instead of bending them However the effects are not as severe as a SID Generally only paths running along east west lines in the higher latitudes are affected with north south paths not disturbed Such conditions are known as ionospheric storms During an ionospheric storm listeners in eastern North America may be unable to hear signals from Europe while stations in Latin America are heard without difficulty Ionospheric storms generally last for only a few days The Future The sunspot number at the peak of a sunspot cycle has ranged in this century from a low of 60 in 1907 to well over 200 in 1958 While the peak of the coming cycle won t be as high as the 1958 maximum it could well be the second highest peak in recorded history Only three times since 1749 has the sunspot number exceeded 150 in 1780 1947 and 1958 The lat
112. after ihis Trial Member ship you will earn a Dividend Certificate for every book you purchase Three Certificates plus payment of the nominal sum of 1 99 will entitle you ta a valuable Book Dividend of your choice which you may choase fram a list provided Members 300 420 p Dictionary of Electronics 10 95 CIRCLE 30 ON READER SERVICE COUPON values to 65 for only with a Trial Membership in the Book Club that guarantees to Save you 25 to 75 on a wide selection of electronics books E each 49 101 416 p Electronic Circuit 1060 308 p 303 Dynamic Electronic Circults 9 95 1064 336 p How io Design Guild Test Complete Spakar Systems 10 95 1015 308 p A Beginner s Guide to Microprocessors 9 95 E a 4 E 929 322 p Solld State Motor Controis 12 95 1023 140 Beginner s Guide tc Designing amp Building Transistor i Radlos 7 95 ELECTRONICS BOOK CLUB Blue Ridge Summit Pa 17214 Please oper my Trial Membership in ELECTRONICS BOOK CLUB and send me the 4 books circled below understand the cost of the books I have selected is only 49 each plus a small shipping charge If not delighted may return the books within 10 days and owe nothing and have my Trial Membership cancel led agree to purchase at least four additional books during the next 12 month
113. age VN gets amplified right along with Vs Now let s suppose R and L represent a piece of 22 wire One foot of 22 has a resistance of 16 14 milli ohms and if I is a direct current of about 61 milliamps then VN equals SWITCHING d CIRCUITRY 9 1 millivolt This is small but certainly significant if Vs is also on the order of millivolts At high frequencies the impedance of inductance L increases to become the dominant factor and this gives us even more trouble For example a foot of 22 wire has a 4 ohm impedance at 1 MHz and a whopping 40 ohms at 10 MHz Need less to say high current and high fre quency stages and this includes our old friend digital logic can wreak havoc on low level circuits Continued on page 86 69 It s Simp BASIC dii by Larry Friedman The odds are 2 to 1 that you ll want to try your luck with Gamble this issue s BASIC program Two COMMON SUBJECTS many of write about are the reproductions of the listing directly from my tele printer and various ways the programs can be shortened and or improved Ac tually there are good reasons for the way programs are handled in ELEMEN TARY ELECTRONICS We photocopy the teleprint of the listings to avoid typo graphical errors because one single typo is all it takes to crash a program Imagine if a typesetter substituted a semi colon for a colon in a multiple statement line it would be a wipe out If you read the
114. aining the actual data followed by checksum to test the validity of the transmission The destination computer would receive the packet perform a checksum and if the data was received intact copy the packet into its mem ory During this time the source com puter would wait to receive acknowl edgement from the destination com puter that the packet had been received and was not lost or garbled After re ceiving acknowledgement the source 51 E COMPUTER READOUT computer would send the next packet If receipt of a packet is not ac knowledged in a specified amount of time the packet is re transmitted until the acknowledgement is received Pack ets are placed into an area of memory in the destination computer known as a buffer When this buffer is filled or when the complete message has been received the destination computer creates a file on the disk and outputs the contents of the buffer onto the disk under an unique file name that can then be accessed by someone who knows that the file is there or who asks the computer to look for a certain file name in the hope that one will be on the disk The Network Given the prerequisites of a means of connection to other computers in this case via modems and the telephone system and an agreed upon protocol a personal computer net work can be set up in a number of ways One possibility is to use a control computer equipped with one or more floppy disk drives as a cent
115. al reading is 1 1 read one to one Most transmitters will accept up to a 3 1 SWR before showing signs of hav ing difficulty loading into an antenna certainly anything less than a 2 1 should be of no concern to your run ning the maximum input power of 250 watts Antenna Tuners If you elected to in stall an end fed long wire as describ ed in the second part of this series you will need an antenna tuner to fool the transmitter into seeing a perfect antenna connected to it A long wire depending upon its length and the operating frequency or a trapped vertical not resonant on the frequency being used may exhibit loads which vary greatly above and below the optimum 50 to 75 ohm load for the transmitter A basic antenna tuner has two varia ANTENNA AR SWRIWATTS L a MFJ VERSA TUNER MODEL MEJ 941 YOUR BNEE THIRD SEMESTER Putting your station on the air Thomas Sundstrom W2XQ The Heathkit HD 1410 is one of the most popular electronic keyers in use today With proper technique there is little fatigue even in extended QSOs Price 49 95 ble capacitors and an inductor Using low power and keeping the transmitter in resonance the two capacitors are adjusted to minimize SWR I should caution you to carefully read the op erating manual of the transmitter and the antenna tuner before attempting to load the transmitter into the antenna You can damage expensive ouput
116. anner indicate all five channel This computerized scanner keeps track of radio traffic without jamming your brains circuits digital time clock indicating hours minutes and seconds that is always on even with the receiver turned off or if the display is used to indicate fre quency Under any operating condition the time is displayed when the time pushbutton is depressed Pressing the button a second time turns off the time display and restores whatever was in dicated prior to the clock display being turned on 50 Channels Next is a 50 channel memory arranged in five switch se lected groups of 10 channels each Any group or combination of groups can be selected for scanning The selected groups are indicated by small dots at the top left of the L E D display Even with the power switch off the on board computer remembers the last group selection and will resume scan ning the selected groups as soon as power is turned on The programming is such that you cannot turn off all groups Attempting to place all groups on standby automatically activiates the channel 1 through 10 group The 1 10 group can only be turned off placed on standby if another group s is selected In addition to the 50 scan channels the Bearcat 250 has a separate mem ory for 64 frequencies These 64 fre quencies are stored independent of the 50 channel programming If desired any of the 64 frequencies can be en tered as channel program
117. another new avenue open for ex ploration with the microcomputer and that is network link up With access to the readout of the computers of large corporations credit balances could be instantly displayed shopping might be done from the comfort of the living room and even your choice of tele vision program may be ordered direct from the network or local cable TV company How about all of those in furiating computer letters demanding payment on bills that you ve paid 5 months ago Haven t you at least once said I d like to tell that computer a thing or two If you had direct access from your own terminal then you could and get an answer back in sec onds The ability to do all of these things stems from the ability of the comput er and micro computer to process the text of a statement in what are called strings Strings are simply groups of alphanumeric characters which are represented in the computer as binary numbers Any written text can there fore be represented within the comput er as binary numbers which can be processed at fantastic speed The most extensive use of this capability present ly is in the generation of those familiar advertising form letters in which your name is repeatedly inserted within the text even though you know that thou sandsiof people are receiving the same letter Computer Networks The string handling capabilities become even more significant when individual computers are tied into
118. ard or chrome tapes and an automatic chrome detector for tapes equipped with a so called chrome detection hole Just mention that this set has a Dolby noise suppression circuit but I haven t seen a Dolby less cassette deck for three years The engineering on the CT F 900 is impressive There are two motors with dual capstan drive and all the tape drive controls are servo operated so that you are free of the usual record ists clicks and clanks There are sep arate record playback and erase bias heads and the performance on our test bench really reflects the effort that was put into this set With Dolby on and using Maxwell UD XL Type chrome tape thc record play frequency response meas ures 0 3 dB from 40 to 13 500 Hz Distortion at the meter indicated zero dB level is 1 1 percent THD with 7 dB headroom to 3 percent THD The signal to noise ratio is 48 dB wideband and 63 dB narrowband Wow and flutter is granite steady at 0 08 percent and the output level cor responding to a zero dB recording lev cl is 700 millivolts The best thing about the Pioneer CIRCLE 54 tre eta Na ee ee Ta N FE Ponce an ce DH Pioneer CT F 900 Cassette Deck CT F 900 however is the microproc essor control This provides memory rewind time controlled record or play preset partial play and repeat all monitored via a bright clear LED nu meric display Instead of your standard VU meter this
119. ards that are used in ELE MENTARY ELECTRONICS construction pro jects Also is there any place near or in Dayton Ohio that makes P C boards from designs on paper J B Dayton OH On a few projects printed circuit boards are available and so indicated in the parts list In others we offer the printed circuit board template free of charge if you send us a stamped self addressed envelope as mentioned in the article The remainder have the board templates printed in the issue Another option is to use the solder less boards They are easy to use and can be used over and over Wheel of Fortune I built that roulette wheel in the Sep tember October 1977 issue of ELEMENTARY ELECTRONICS and it works great While 1 was building it I found that if you add an 8 ohm speaker between ground and the junction of R19 R20 and b2 of Q13 you get a clicking sound that is in sync with the LED s It is kind of neat to hear the blinks I just thought you would like to know what 1 discovered S S H Colorado Heights MN The LED roulette wheel was a real hot project Glad that you and many others for the Experimenter INTERNATIONAL CRYSTALS and KITS OF 1 OSCILLATOR 54 The OF 1 oscillator is a resistor capacitor circuit providing oscillation over a range of frequen cies by inserting the desired crystal 2 to 22 MHz OF 1 LO Cat No 035108 18 to 60 MHz OF 1 HI Cat No 035109 Specify when ordering MXX 1 Transisto
120. ation Compatible with SWTPC cas sette software Optional kit permits program control of cassettes Optional adaptor permits inter facing with any computer Upgrade your SWTPC 6800 system to 1200 baud with PerCom s CIS 30 dual cassette terminal The CIS 30 four times as fast as SWTPC s AC 30 with the same dual cassette capability plus a 1200 baud data terminal interface in a SWTPC color compatible package that s only 1 10 the size of the AC 30 Dependable The simplicity of Harold Mauch PerCom Data designs says more dependable dual function interface you can buy for your SWTPC 6800 See your nearest dealer or order direct from PerCom PerCom peripherals for personal computing 14 CIRCLE 16 ON READER SERVICE COUPON interface PERCOM DATA COMPANY INC than any well chosen words Simply put for only 79 95 you get the fastest MOSt Depr c 318 BARNES GARLAND TX 75042 214 272 3421 Kit price Assembled and tested 99 95 shipping Tex res add 5 tax BAC amp MC available ELEMENTARY ELECTRONICS January February 1979 The New Realistic High Power 5 Way Speaker for Sensational Autosound 6x9 Woofer 2 3 4 Midrange Solid State Tweeter A car speaker like no other Why We gave it a big woofer with a 1U4 pound magnet and a layer voice coil tor deep and powerful bass without cone breakup and distortion For midrange realism
121. binet Construction Ideas Setting Up the Sys tem Specifications and Cost Estimates Nagler points out that maximum bright ness contrast and sharpness should be achievable at the highest brightness con trol setting and that regardless of the TV used one should have excellent reception to fully enjoy the giant picture Prices ap proximated above include all the ma terials but not the price of the TV set The simplified booklet which has been de signed to save money and to give the family an interesting weekend project can be obtained by mail Stock No 9565 by writing to Edmund Scientific Co The Edscorp Bldg Barrington NJ 08007 An Edmund catalog cover priced at 1 00 can be obtained free by writing to the above address Get Started Now you can study basic electronic principles at home and use what you learn in simple experiments NCR Basic Electronics Course with Experiments offered by E amp L Instruments teaches basic electronic circuit principles in a home study text written for technicians and hob byists Prepared by the technical educa tion department of the National Cash Your introduction into electronic experimentation qane MENON gog EES T Soft cover yo CUN 440 pages UNS 9 50 TERMINAL UNE giS 30 s nnn e Record and playback at 120 60 or 30 self clocking bytes per second extended Kansas City Standard 1200 600 or 300 baud data terminal interface Dual cassette oper
122. bus Ohio Today Missouri Institute of Technology Kansas City Missouri DeVry Technical Institute ADDRESS Woodbridge New Jersey Equal opportunity in placement CITY housing and admissions Return coupon 7 Compare our job placement record with any school s Any Probably there s nothing more convincing to be said concerning the quality of our electronics education programs beyond the simple statement of our placement record In 1977 more than 92 of the graduates seekin their training within sixty days after graduation Although we can t guarantee jobs we know of no school in our field that exceeds this record of success We invite you to compare Then if you d like to know more about how easy it may be for you to acquire an electronics education call us or return the coupon below BELL 5 HOWELL EDUCATION GROUP Inc BELL amp HOWELL EDUCATION GROUP INC 2201 W Howard Evanston IL 60602 g our assistance were placed in jobs related to AGE STATE m d PHONE 8x4152 poem CIRCLE 41 ON READER SERVICE COUPON ELEMENTARY ELECTRONICS January February 1979 23 lnm DeNinno ok ars z Old amp Rare Coins Old Indian Head Cent V Liberty Nickel Bubalo Nickel Large Cent eng 1943 WWII Cent 1 Cent 1920 or Older Wooden Niche D Must Cent 25 years oj 95 BUYS THESE TWO i RARE UNCIRCULATED COINS i
123. by the various commercial names being used a matchbox or a transmatch are other terms used in the literature but they refer to the same type of product we re discussing Do you absolutely need an antenna tuner No If your antenna is resonant and the transmitter loads properly an antenna tuner is not necessary How ever some amateurs use tuners re gardless of whether or not their anten na systems are tuned properly tuners can help reduce harmonics and other spurious signals that may be radiated from a multi band antenna TV Interference Television inter ference TVI is a touchy subject these days Diplomacy is a key word if you get complaints from neighbors The local FCC office has a brochure to help you explain Why TVI The best defense is a good offense If your own televisions are free from interference that is a powerful argu ment to show that your equipment is not at fault On the frequencies below 30 MHz probably the most damaging TVI is caused by harmonics multiples of the fundamental frequency Most Novices seem to have the worst problem with the third harmonic of 21 MHz 15 meters tearing up channel 13 60 66 MHz Filters may help here R L Drake Company and Barker amp Williamson are the two largest manufacturers of both low pass and high pass filters A low pass filter will pass frequen cies lower than a cut off frequency of 30 or 40 MHz The low pass filter is mounted at the rear of the transm
124. c offers all the car sounds for the travelin man speakers amplification systems radios speaker accessories along with CB anten nas all presented in 4 color pics with descriptions 377 We can t enumerate all the products in John Meshna Jr s catalog of surplus electronic parts power supplies computer keyboards kits for alarms clocks speakers and more 378 Delta Electronics is a complete parts source for electronics experimenters Discrete parts mod ules boards subassemblies and complete gadgets Get Delta s 120 page catalog today 379 There s everything in the area of musical synthesizers for drums strings other instruments and ful orchestras as well as audio gear video display modules and a computer in PAIA Elec tronics catalog 362 B amp F Enterprises Truckload Sale catalog of 380 If your projects call for transistors and FETS fers 1096 off all merchandise military or indus linear and digital ICs or special solid state parts trial surplus speaker kits TV games computer then look into Adva Electronics mini catalog for termina s tools TV components lenses and more rock bottom prices and applications of 160 chemicals compiled for electronic production and packaging They are used for all types of electronic equipment 320 Edmund Scientific s new catalog contains over 4500 products that embrace many sciences and fields 22321 Cornell Electronics Imperial Thrift Tag Sale Catalog
125. car Accelerating out of Turn 4 at the Indy 500 a championship race car driver like Mario Andretti or Janet Guthrie will be passing through 200 mph a situation demanding 10046 con centration on track and competitors To see how fast they are driving they might take a passing glance at their tachometer an instrument that meas ures engine speed in revolutions per minute rpms If the tach reads 7800 rpms at a place where it used to read 7700 they know they have picked up a few fractions of a second on their lap time Even if you are not a racer you can take advantage of a tach it will help you pick a fuel efficient cruising speed tell you when to change gear or make your back yard tune ups a snap One of the neatest tachs we ve seen lately is this Indy Cator Dual function Digital Tachometer Model 17306 It will measure engine speed in revolu tions per minute on any four cycle en gine with spark plug ignition The tach ometer will read engine speeds of up to 9 900 rpms with an accuracy of plus or minus 100 rpms It operates by detecting ignition pulses on one of the spark plug cables The digital read out is updated every 1 2 seconds In addition to reading instantaneous rpm the unit is capable of storing a preset Red Line speed When the 50 There s no hard wire connection to your car s ignition system with this tachometer Ali you need do is wrap the sensor wire around any of the spark plug wires at any poi
126. cial license to pos sess and use it in your state To use the Mutt Minder you just press the button on top of the unit while waving it in the dog s face The dog will associate the harshly unpleas ant noise with you and Mutt Minder and retreat Remember that discretion is the better part of valor do not test CIRCLE 50 ON TN READER SERVICE COUPON this on attack dogs or extremely men acing dogs They may instinctively at tack rather than retreat How It Works The heart of the circuit is an ultrasonic transducer which will oscillate at around 20 000 Hz when driven by an oscillator based on a 555 timer chip The transducer takes a lot of power Two 15 volt batteries in series put a 30 volt potential across Shown above are the optional printed circuit board 4 50 and perf board methods of construction Note how we attached the battery holders with pop rivets on the perf board The ultrasonic transducer is the heart of the circuit emitting a 20 kHz tone 60 tae The finished product is no larger than a pack of cigarettes and is easily carried the power transistor and the transducer Don t overuse it the batteries do not last very long If you have had any electronic as sembly experience whatsoever then putting Mutt Minder together will be easy If not then go slowly The in structions are abbreviated but adequate and with a little patience you should have an operable hound h
127. cked by the rising edge of the positive clock pulse and the high is fed to the D flip flop input the D flip flop sees the falling edge of the inverted clock pulse and just sits there with its output still low A few milliseconds later at the end of the clock pulse the D flip flop is clocked and then the high is trans ferred to its output pin 13 of IC4 which connects to the load enable in put of the shift register pin 7 of ICS 6 and 7 This puts the shift register into the parallel mode Nothing hap pens until the next clock pulse at the beginning of which the shift register is loaded with a high in stage 1 and lows in the other stages and at the end of which the output of the D flip flop goes low putting the shift register back into the serial mode The situation is now the same as it was when we began our analysis and the whole sequence re peats Here we have been assuming that S3 is set to a number 2 12 caus ing the shift register to keep reloading automatically as described so that the sequence repeats indefinitely However if Sequence Length is set to off the high the shift register is shifted through all 12 stages and out the end without being fed to the D flip flop so the shift register is not automatically re loaded Thus the sequence only oc curs once after which the R amp B Box quiets down To start the action again it must be loaded manually The shift register is loaded manually by means
128. costs something over twice as much as the baby brother that is between 500 and 600 The big improvement in the 7000 model is the addition of electronic dig ital frequency readout to an accuracy of one kilohertz Also the receiver has an LED light emitting diode digital clock which can be switch selected Down The Dial Times in GMT frequencies in kilohertz 3 985 If this month s lead article on Colombian sta tions has whetted your interest why not try for this station in neighboring Ecuador The station an educational voice is Radiofonicas Poulares in Rio bamba Try around 1030 GMT 4 803 There is another Ecuadorian station with a similar sounding name Radio Popular de Cuenca on this fre quency though it may vary a few kHz up or down During the evening hours say around 0500 to 0530 GMT or so you can often hear this station with the distinctive and plaintive music of the Andes If you re familiar with Simon and Garfunkel s El Condor Pasa you ll know what I mean 6 135 Radio Tahiti is always a fun catch especially when the station gets going with its pulse pounding island today and go a crafting All Craft Prints are unconditionally guaranteed if you are not completely Z Build the REAL THING Yourself Whether your thing is nautical a Pow r Pup or a suburban tractor the CRAFT PRINT DO IT YOURSELF Division of Davis Publications has it for you Order your new catalog 3 AMAZ
129. ctive carrying case Palmetto Internation Corp P O Drawer 1306 Lake City SC 29560 Mirror Image Speakers A new bookshelf size loudspeaker sys tem the Koss CM 530 has been com puter assisted in its design in order to achieve maximum musical performance It comes in mirror imaged pairs to as sure identical musical reproduction from the right and left speakers providing listeners with a very natural life like sound The system has flat frequency response range and deep bass The three position treble control switch per mits the listener to alter the high fre quency response to suit room charac teristics source material and personal taste The Koss CM 530 cabinet is fin ished in select pecan wood veneer with a removable chocolate brown fabric grille cover Weighing 35 bs and measuring 24 in by 13 in by 11 in each the CIRCLE 60 ON READER SERVICE COUPON speaker system has a suggested retail price of 175 00 For details on the CM 530 and other Koss products write to Koss Corporation 4129 N Port Washing ton Ave Milwaukee WI 53212 Four Band Portable Scanner A new scanning monitor receiver the Bearcat Four Six by Electra combines reception of VHF and UHF bands in one portable unit The Four Six scanner named for its four band six channel capability measures just 3 in by 7 in by 2 in and weighs only 12 ounces Each of the six channels has a bright red LED indicator light and individual
130. d Stem Vacnnn BUSINESS OPPORTUNITIES Cont d MANUFACTURING Business paying High Weekly Profits Begin home spare ful time Many oppor tunities presently available Without investment Businesses 92 D Brighton 11th Brooklyn NY 11235 OVER 16 50 an hour Spare time at home Rubber Stamp industry needs small manufacturers We fur nish all equipment and know how Particulars free Write Roberts Room RC 107 IA 1512 Jarvis Chi cago IL 60626 500 Monthly Clipping Newspaper items Experience unnecessary Free Details American 1108 Colonial Inkster MI 48141 Classified Ad That Pulls E ond La dow O MAKE YOUR CLASSIFIED AD PAY Get How to Write A Classified Ad That Puls Includes Certifi cate worth 2 00 towards a classified ad in this publi cation Send 1 50 plus 25 for postage to R 8 Wayner Davis Publications Inc Dept CL 380 Lexington Avenue New York NY 10017 E PLEASE Be sure to include your zip code when ordering merchandise from classified advertisements You ll receive faster delivery ULTIMATE Security System for homes businesses property Not an alarm not a gimmick A remark ably innovative product with 17 issued patents Noth ing else like it Re lable effective inexpensive Send 1 00 for complete information Security Control Re search 832 West First Birdsboro PA 19508 Dealer ships available DIRECT TO FARM SALES New Paten
131. de in U S A ANIXTEt MARK 5439 W Fargo Skokie IL 60076 312 675 1500 Mail this coupon for additional information on the BROAD STICK and the other fine Anixter Mark products NAME ndi RAMONES a COMPANY ADDRESS e wm um a UD GP GR UD GD am ws UD UD UD UD UD CD UD UP UD UD UD GP GP Wb my STATE AP CIRCLE 21 ON READER SERVICE COUPON For cost effective capacitance measurement One C meter stands out of the darkness the 130 B amp K PRECISION 820 For about one third the cost of the most popular digital Capacitance meter you can own five times more measure ment capability The new B amp K PRECISION 820 reads from O 1pF all the way to 1 Farad in ten ranges With 0 5 accuracy the 820 resolves to O 1pF for a maximum count of 9999 The 820 retains its high accuracy in freezing cold to blis tering 100 degree heat making it ideal for field use The bright LED display is easily readable under lighting conditions It has the versatility needed for any application and the dura bility to stay on the job The 820 can be powered by dispos able batteries or optional rechargeable batteries You can start discovering your own applications today by seeing your local distributor for immediate delivery Unlike many specialized instruments the 820 has almost unlimited applications in engineering production line work QC education and field service First time use
132. deck has a bar graph type flourescent display that not only gives average recording level but can be programmed to read peak recording level or hold on the highest peak in a section of music For more information about the Pioneer CT F 900 circle number 54 on the reader service cou pon Sanyo RD 5350 Dolby Cassette Deck The RD 5350 is an excellent low to medium priced 219 95 cassette deck that performs very well with budget priced tapes It features a bias equali zation switch with positions for normal ferrichrome and chrome tapes two well calibrated VU meters three peak recording level indicators calibrated at dB 3 dB and 6 dB and of course Dolby CIRCLE 68 Sanyo RD 5350 Cassette Deck It has smooth functioning piano key type tape controls switches for power Dolby input selection bias and equal ization and controls for left and right input levels and ganged output ELEMENTARY ELECTRONICS January February 1979 Using TDK SD tape but without Dolby the record play frequency re sponse measures 0 6 1 8 from 40 to 14 000 Hz down 2 5 dB at 35 and 15 000 Hz THD is 1 1 percent with 5 dB headroom to 3 percent THD The signal to noise ratio is 49 5 dB With Dolby however the signal to noise ratio is up to an impressive 55 dB widcband and 59 5 dB narrow band with some loss in frequency re sponse The maximum output level cor responding to a zero VU average re cording level is 620 millivolts
133. e quency circuits are the most trouble some noise sources as far as the elec tric field is concerned Digital logic 15 one of the most common examples of this type of circuitry Signal swings are large between five and fifteen volts usually Furthermore even though the repetition rate of the pulses or square waves involved may be low these sig nals still have a high harmonic content For example pulses with a 5 nano second rise time have significant har monic energy right up to 30 MHz even if the repetition rate is much less than that At the receiving end the most noise susceptible circuits will have high im pedances and operate at low levels that is with small V2 This latter factor low levels is very often accom panied by high gain Common exam ples of such noise sensitive circuits are high gain FET preamps low level an alog comparators and op amps with large feedback resistors Assuming that you cannot change the design of the source and receiver circuits the only practical method of reducing noise from an electric field is to minimize the coupling capacitance Separation of the two stages helps at least an inch or two should intervene between the circuits Separation be yond this distance will reduce pickup still more but the noise level does not drop as quickly as it does over the first inch or so Shielding More effective than sepa ration is the use of metallic shield when pickup is severe
134. e is terminated and soldered inside for positive electrical contact reducing the potential of wire breakage SWR is check ed after initial construction and checked again after a super strong black heavy duty polyolefin dielectric shielding is ap plied to assure a consistently low SWR under 1 5 1 over 40 channels more Road Hog Antennas come in three sizes Model 335 is 48 in 16 95 Model 336 is 60 in 17 95 and Model 337 is 69 in 18 95 All three are avail able separately or in a variety of single CIRCLE 75 ON READER SERVICE COUPON and double kits The single kits are pre wired with Valor s exclusive in line mini connector system Hog Antennas are now available in three colors red black and white For more information on the Road Hog or any Valor Communication prod uct write to Valor Enterprises Inc 185 West Hamilton Street West Milton OH 45383 Preassembled Beam CB Antenna Channel Master has just introduced a CB beam antenna called Signal Tracker The new beam antenna can be com pletely assembled and ready for mount ELEMENTARY ELECTRONICS January February 1979 ing in less than 10 minutes Its elements Snap into place like those elements found on preassembled TV antennas Takes less time to assemble and re quires very few pieces of hardware Sig nal Tracker is a high efficiency CB beam antenna made of heavy strength drawn aluminum tubing Its boom length is only 12 9 ft Signal Tracker featu
135. e connectors are included The IM 4190 kit retails for 114 95 and the SM 4190 assembled version 195 95 mail order Benton Harbor For more infor mation on the IM SM 4190 write Heath Company Dept 350 630 Benton Harbor MI 49022 Lab Power Supply Intended for engineers and discriminat ing hobbyists who design and test bread boards and prototypes a new low cost dual output bench power supply from Hewlett Packard offers two independently adjustable and isolated power sources in one compact unit Both of the DC power sources are of the constant volt age curent limit type with each output voltage being adjustable continuously over a 0 to 25V range The maximum curent available per output is 0 2A and CIRCLE 55 ON READER SERVICE COUPON is limited automatically to prevent over loading The outputs can also be con nected in series to provide up to 50V at 0 2A Both sources are full isolated to permit either of the output ter minals to be grounded With pushbutton switches users can select either voltage or current for each output to be moni tored on the unit s meter Other features include two multiple turn controls for pre cise voltage setting regulation to 0 0196 and ripple and noise of less than 200 microvolts rms The Hewlett Packard Model 6234A dual output power supply is priced at 175 00 U S price only For more information write to Inquiries Manager Hewlett Packard 1501 Page Mill Rd Palo Alto CA 94304
136. e not required for an understanding of our upcoming discussion each aid has some useful information that will probably be of interest to you 3 Rhythm amp Blues Continued from page 33 1 followed by eleven softer ones corresponding to pots 2 through 12 The brightness of the LED flashes should follow the same pattern Holding the Reset Start button in should stop the clicks Releasing it should immediately start the sequence of clicks again beginning with 1 the loudest Now set Sequence Length to 11 a repeating sequence of one loud click followed by ten softer ones should be heard Similarly check Sequence Length settings of 10 9 8 etc When changing the Sequence Length setting the pulse may be lost from the shift register with the result that the clicks are no longer produced This is normal and if it happens simply push and re lease Reset Start to restore operation With Sequence Length at off a se quence of twelve clicks should be pro duced the first one should be loudest 88 each time Reset Start is pushed and released Check that the loudness of each of the twelve clicks in the sequence can be varied from zero to maximum by ad justing the corresponding pot The brightness of the LED flashes should also correspond approximately to the pot settings Finally adjust trimpot R9 ot give the desired sound quality to the clicks Performance After going through the circuit descrip
137. e pulses if not make the adjustment by ear First set the 100 K pot which you temporarily wired in place of R28 for maximum resistance Turn the synthe sizer on and start it pulsing Now slowly decrease thg resistance of the pot which should cause the amplitude of the pulses to increase up to point of Saturation in other words a point where the amplitude of the pulses no longer increases with a further decrease of the pot s resistance Back the pot off slightly from this point and without disturbing its setting unplug the syn thesizer and remove IC11 Measure the combined resistance of the pot and 10 K resistor and install in their place a fixed resistor of the same value or the nearest standard value Reinsert IC11 start the R amp B Box again and continue the checkout by turning all the numbered pots except 1 down to about 4 This should result in one loud click corresponding to pot Continued on page 88 ELEMENTARY ELECTRONICS January February 1979 LE 5 1 6 L T CD4035 CD4035 C04035 ELEMENTARY ELECTRONICS January February 1979 by Harry L Helms Jr WA4EOX SUNSFOTS bearing good news and bad for the Ham SWL and CBer LD SOL FINALLY AWOKE from it s long quiet spell and sunspots are appearing all across the face of the sun If you re a SWL or ham operator this means happiness as rare DX sig nals begin to roll in from around the globe on the higher frequencies If you re a CBer
138. ead to the load and monitoring the load voltage with a voltmeter In this case load volt age regulation now depends on zener diode characteristics When recharging batteries with the Mini Reg connect a silicon rectifier diode in series with the plus lead going to the battery This eliminates leak when the supply is turned off with battery yet connected Observe battery polarity when making connec tions Circuits using op amps usually require a dual or split supply To pro vide a dual six volt supply set the out put voltage to fifteen volts set S3 to 100 milliamperes and connect two six volt zener diodes in series across the output terminals Then connect a 100 uF 25V electrolytic capacitor across each zener diode The Mini Reg handily checks and sorts zener diodes of fifteen volts or less Set R11 for fifteen volts output and set S3 to ten milliamperes Connect the diode across the output terminals with plus lead wire to BP1 Observe zener diode voltage on M1 Advance S3 to high currents but do not exceed rated current of the diode The better the quality of the diode the less increase in voltage observed on M1 When you operate radio or audio equipment from the Mini Reg set S3 to a current level which supplies peak currents on audio peaks Otherwise you will notice audio distortion on audio peaks With some radio and audio equipment operations off an AC adap tor or the Mini Reg may introduce an AC hum
139. ee manuscript report Carlton Press Dept SMM 84 Fifth Avenue New York 10011 BIG MAIL RECEIVE MONEYMAKING OPPORTUNITIES Your name placed with 2 000 importers wholesalers manufacturers etc Year listing 1 00 SAVE 160 00 Postage Advertising Agency Box 123 YNA We nonah NJ 08090 BLUEPRINTS PATTERNS amp PLANS NEW CRAFT PRINT CATALOG Choose from over 100 great easy to bulld plans Send 1 25 completely refunded with your flrst order BOAT BUILDER CP Div 380 Lexington Ave New York NY 10017 WHAT S going on in housing Get advice on how to economize in modernizing or improving or adding space from idea to completion Working blueprints available Send 1 50 includes postage for 110 Bet ter Building Ideas to Davis Publications Inc 380 Lexington Ave New York NY 10017 BOOKS amp PERIODICALS FREE CATALOG SELF IMPROVEMENT BOOKS The Mall Sack Dept C1179 600 Welch Blvd Flint Michigan 48503 CBer s Personalized CB decal with a 1 year sub scription to Elementary Electronics only 3 97 E E the magazine that covers CB and al areas of radio communication Send check Elementary Electronics Decal Dept 380 Lexington Ave New York NY 10017 BUSINESS OPPORTUNITIES BECOME our Mail Order Distributor with 150 investment Free brochure Audit Controls Box D 35 Emerson NJ 07630 BORROW ANY AMOUNT Enjoy A 1 credit Keep poner in hank cet AN mare San
140. egative going pulses at regu lar intervals Once calibrated to the proper rate this multivibrator remains at a constant frequency The clock has two main jobs It must SEVEN SEGMENT LED DISPLAYS LATCH ENABLE This photo shows the layout used in the demonstration model The event input was from a 555 based code practice oscillator Even CLOCK better would be an AF RF Signal generator with a variable square wave output jack DECADE COUNTER DIVIDER BCD TO SEVEN SEGMENT LATCH DECODER DRIVERS a UP DOWN DECADE COUNTERS RESET CARRY OUTPUT EVENT INPUT TO COUNTER INVERTER ELEMENTARY ELECTRONICS January February 1979 reset the entire counter circuit to zero at the appropriate time and it must freeze the display at the appropriate part of the counting cycle so that it is a readable and meaningful number rather than a blur of speeding digits This last task requires a device known as a latch A latch is a circuit that freezes on whatever BCD number is in its register when a high voltage is applied to the latch enable pin If your circuit is counting from zero to 1000 every 10 seconds and you put a high voltage on the latch enable pin at 6 seconds the display will hold at 600 If it is grounded at seven seconds the display will resume the count at 700 So the count doesn t stop it is only the display that freezes In the circuit shown on these pages the latch is incorporated i
141. eil Shapiro WB2KQ ITH A SIGH BORN of both triumph relief you turn away from the control board of the USS En terprise and order the crew to stand down from Red Alert On the view screen the Klingon starship that once swooped down on you like a techno logical bird of prey is now only a de stroyed cloud of expanding gas a wispy nebula against the starry sky Having defeated the might of the Klingon Empire you now turn to your next adventurous assignment Perhaps it will be governing the ancient land of Sumeria filling in for old Hammurabi Being a benevolent despot can be fun but there are dangers attached If you estimate your crop yield too low do not allow for population expansion sell off too much farmland then ycu re bound to starve a good percentage of your countrymen whose outraged sur viving relatives might just assassinate you Maybe you ll go to the horse races play a quick game of craps for a thou sand dollars a throw sit at an exclusive Blackjack table with a wise cracking dealer or indulge in any of hundreds of games of skill and chance If you own a personal computer you already know that gaming is one of the most popular uses for the hobby ist s machine Of course there are other more useful applications But when it comes to simple enjoyment thousands of hobbyists turn to games ye e NL You don t have a personal computer The thought of programming even in a high level
142. electric shield Aluminum a common cabinet material is excellent at all frequencies A shield may be placed Figure 3 between two stages of a single piece of equipment On the other hand a grounded metallic cabinet constitutes a shield between a particular piece of equipment and all noise sources in the outside world The only precaution necessary when shielding is that the shield must be in electrical contact with the circuit s ground Note that this does not necessarily mean an earth ground such as a pipe in the soil Con nection to circuit common is all that is ever required At this point you are probably wondering what happens if the source and receiver circuits do not share a common ground connection We can treat this coupling by means of two stray capacitances as shown in Fig ure 3 You should be able to see for yourself that the previously discussed shielding methods still apply A shield around either circuit connected to that circuits ground potential is all that Is required Before leaving the electric field case let s note that wires may also need shielding if they connect to possible receivers or sources When wires exit a particular piece of equipment they may be protected by shielded cable Likewise shielded cable may be used within a single piece of equipment when interstage noise coupling is a problem Often however you can ob tain the benefits of a partial shield by simply routing wires close
143. en cabinet radio First remove the knobs back radio chasis and speaker Carfully wash the cabinet and dial glass Use warm water and a dish washing detergent then rinse and wipe dry Washing should remove dirt grease etc but will leave paint spots Your fingernail or alcohol will usually remove the paint After washing the cabinet will probably still be dull and dingy looking so a plastic cleaner and polish should be used to restore the original luster The best polish and cleaner I ve found is Meguiar s Mirror Glaze Plastic Clean er and Plastic Polish They are sold by Mirror Bright Polish Co Inc Irvine CA 92664 A catalog source is listed in the appendix Once again an old tooth brush will be handy to clean the grooves in the knobs and cabinet Follow the direc tions carefully when you are cleaning and polishing your cabinet and it will look as good or better than when it came from the factory The appendix lists sources to whom you can write for tubes schematics and other parts for set restoration You will also find a listing for hard to find tools brushes etc The source of the Paint and Varnish Remover is also listed We have tried to give you the over all picture of what is involved in re storing a small table model radio so you will have a set you will be proud to show to your friends and neighbors A lot of these small wooden radios are still available so look around 3 Sunspots Continued
144. en rhythm typical of Eastern music Such rhythms are frequently troublesome but are easily handled with our rhythm syn thesizer If you need to analyze such rhythms it may be helpful to turn on the silent beats slightly in this ex ample 2 3 5 and 7 The final example 6 illustrates how the synthesizer can accommodate fairly complex rhythms All twelve pots are needed since the smallest time unit is a 1 16 note and the total pattern duration is 6 8 or 12 16 Off Beat Uses As mentioned at the beginning the rhythm synthesizer is also useful as a programmable control ler for electronic music synthesizers and other equipment The Control Voltage Out jack J2 puts out a se quence of voltage levels corresponding to the settings of the numbered pots For example the sequence of voltage levels can be fed to a VCO voltage controlled oscillator to generate pro grammed melodies of up to twelve notes If you want to try this two sim ple VCO circuits which can be control led in this way by the rhythm synthe sizer are given in the figure You can also use the R amp B Box as a waveform generator for square pulse staircase and other waveforms again by using the signal from the Control Voltage Out jack To get an idea of the possibilities connect an oscilloscope set at a slow sweep rate to J2 turn Tempo all the way up set Sequence Length to 12 and vary the numbered pots In case you want to run your rhy thms thr
145. en that digit is being decoded Mul tiple digits are decoded in sequence so rapidly that they appear to be all lit at once More Help Two books which were extremely helpful in putting this cir cuit together are CMOS Databook by Bill Hunter and published by TAB 984 6 95 and Radio Shack s Archer Semiconductor Refer ence Handbook 276 4002 1 95 You can learn a lot from these and other books but nothing takes the place of actually putting one of these circuits together It is only by trial and error that you learn how to use these basic digital building blocks learn how to get all the parts ticking over in the proper sequence and humming along to the beat of the clock the way a good orchestra plays to the rhythm of the conductors batton E ELEMENTARY ELECTRONICS January February 1979 GETTING series we ve talked about selecting either a transceiver or separate re ceiver and transmitter and then about instaling an antenna Now let s com plete the installation by matching the transmitter to the antenna It s not just as simple as plugging things in The transmitter transmission line and an tenna all have to be tuned to each other s electrical characteristics This operation requires the optimization of what is known as the SWR short for Standing Wave Ratio The Perfect Match The SWR is a measure of how much of the power that is poured into the transmission line and antenna by the transmitter is wast
146. enta tions To continue the checkout set the controls as follows pots 1 through 12 fully clockwise Tempo about of the way clockwise Sequence Length to 12 Volume fully clockwise Light to on Turn the power on and push and release Reset Start Immediately after it is released a continuous series of clicks should be heard actually the synthesizer may start without pushing Reset Start The clicks should all be equally loud at evenly spaced intervals and the LED should flash for each click Sour Notes If your R amp B Box does nt behave as it should first recheck ihe PC board and all wiring Make sure the IC s are properly installed and oriented Next try to determine which indicates that the clock IC2 and IC3 is working Check for a series of 10 volt pulses at the Exrernal Amplifier jack which indicates that the shift register IC5 6 and 7 and analog switches IC8 9 and 10 are work ing If either the sound or light oper ates but not the other check the ap propriate output circuitry If one of the clicks is weak or absent look for a problem in the corresponding stage The troublesome stage can be identi fied by varying each numbered pot in turn Assuming everything is OK the next step is to determine the optimum value for R28 Verify that all controls are set as specified earlier be sure that Volume is at maximum If you can get an oscilloscope connect it across the speaker terminals to observe th
147. er has neither eddy current nor hysteresis losses TYPES OF TRANSFORMERS There are many varieties of transformers ranging from huge power station units to tiny subminiature radio frequency types i BADIO FREQUENCY TRANSFORMER Tm Most transformers are designed to transfer power Others however are built to transfer only Signal voltages Power distribution transformers are rated in KVA kilovolt amperes rather than in kilowatts or other power units The KVA rating refers to the apparent power carried by the transformer the real power is smaller by the load power factor Special transformers wound to precision specifica tions are used in metering applications to measure the current and voltage passing through large power trans 81 mission lines A step up transformer increases voltage which in creases impedance and decreases current resulting from an increased impedance at the same time A step down transformer decreases voltage which de creases impedance and increases current which re sults from a decreased impedance at the same time Therefore a transformer changes impedance but the impedance change is more pronounced than the volt age change In fact a transformer changes impedance by the square of the turns ratio QUESTIONS 22 If the primary of a transformer has 10 000 turns and the secondary has 1 000 turns what is the turns ratio 23 If 100 volts is applied to the
148. er you will find old meter movements at almost every Amateur Radio Hamfest flea market I ve found several and the price is usually right You can pur chase nice old meters for prices rang ing from 50 cents to 5 00 Carrier Current Radio I recently re ceived a letter from George Hausske of Wheaton Illinois that included a story about Carrier Current Radio Carrier Current Radio while unfamili ar to many has been in commercial use since 1928 The equipment is very simple a modulated oscillator on a frequency of 70kHz is sufficient for transmitting while a power detector is often adequate for voice signals and telemetering Public Utilities and electric gen erating systems are now the largest users of this equipment Their trans mission lines lend themselves to use as one conductor of the signal with ground used as the return conductor The transmitter power is coupled through capacitors to isolate the trans mitter from the high voltage on the power lines Low frequencies such as 70 kHz tend to follow the wires and are not radiated into space as are the higher frequencies Large wave traps Continued on page 93 ELEMENTARY ELECTRONICS January February 1979 CIRCLE 79 ON READER SERVICE SAL A SCANNER THAT THINKS FOR IT SELF is about the best way to describe the Bearcat 250 Five Band Scanning Receiver No longer need the user know the precise frequency of a sta tion or service the Bearcat
149. ercial assem bly line units with lessons retro fitted to what was at hand NRI has designed each so you get invaluable training and experience you just can t get any other way As you build you study operation of circuitry see how sections interact perform power on experiments only possible with NRI This total training is exclusive with NRI no other school home study or resident offers it Instructors Who Know Their Business NRI instructors are thoroughly qualified with both technical and educa tional experience Most of them helped develop NRI courses lessons and equip ment so they really know what they re talking about They re interested in their students always ready to help with a question a problem give good advice to help you reach your goals It s instructors and training like this that have made NRI the choice of professional TV servicemen who have taken home study courses As a national survey shows summary on request they recommend NRI by a majority of three to one over any other school So how does NRI give you all this and still cost so little We keep costs down by designing our own training kits eliminating the middleman s profit on hobby kits or commercial units And by offering our training by mail only We have no sales force no commissions to pay You make up your mind in your own time without pressure let the facts speak for themselves We pass these savings on to you in the fo
150. erefore for rough calcu lations it is permissible to assume 100 efficiency As with any other device the efficiency of a trans former is equal to output power input power Most transformers have an efficiency in the range of 97 to 99 So even if you neglect the losses your calculations using 100 as the transformer efficiency will still be accurate within 1 to 3 TRANSFORMER LOSSES The power loss in transformers is due to three fac tors The first is simply resistance in the windings no winding is a perfect conductor The second factor that causes power loss in trans formers is eddy currents The iron in the core of a transformer is a conductor When the changing mag netic field produced by the primary coil cuts through the iron of the core small currents are generated in the core material These currents dissipate power as they pass through the resistance of the iron These currents are called eddy currents This type of loss is held to a minimum by using thin sheets of iron called laminations in the core These thin sheets are insu lated from each other often by oxidizing the surface of the sheets and thus shorten the conducting path for the eddy currents The third factor that causes power loss in transform ers is hysteresis It takes a certain small amount of power to magnetize a piece of iron This power must be expended again when the magnetic feild is re versed Since the magnetic field in a transforme
151. essentially constant current to the load at a level depending on the value of Rsc In the schematic diagram resistor R3 places a minimum load on the regulator Switch S3 selects the desired current limit Jacks J1 and J2 permit insertion of a milliammeter to read load current but without impairing regulation Diode D2 provides meter protection and diode D1 provides reverse voltage protection Construction Assemble the Mini Reg in an aluminum case or a plas tic case with aluminum cover plate Select a case which will accommodate the particular meter and transformer you plan to use Plan the layout allow ing room for the PC board assembly when the cover plate is secured Begin by laying out and drilling mounting holes for in the heatsink Drill a 7 16 inch diameter hole in the heatsink to pass the lead wires of ICI File off drill burrs and ridges so that IC mates perfectly on the heatsink Drill match ng holes in the cover plate For ventilation drill a number of holes in the cover plate and on the bottom of the case Make the PC board using the circuit pattern shown taking care to locate ELEMENTARY ELECTRONICS January February 1979 ZZ 567 12 I LIMIT pads for ICI just right Push IC1 into the drilled board and mark and drill the mounting holes For easier mating countersink the lead holes for IC1 on the insulation side of the board by twirl ing a small drill bit Install and solder t
152. est sunspot cycle peak in 1969 peaked at only 120 The Space Environment Services Center in Boulder Colorado predicts that we are headed for a peak sunspot number of approximately 153 during the first six months of 1980 Yet cur rently the sunspot number is running ahead of the Center s prediction For example the predicted sunspot number for February 1978 was 64 the actual sunspot number for that month was already one of the highest in history 90 Thus the predicted peak of 153 ELEMENTARY ELECTRONICS January February 1979 may actually be on the low side What kind of radio conditions will we experience during this cycle peak Hams and SWLs will delight in the improved conditions on the higher shortwave frequencies Many bands above 14 MHz will be useful for world wide communication around the clock and not much power will be required to span the globe Hams who like to chase DX on the six meter 50 54 MHz band will likely find this band useful near the cycle peak for world wide communications as was the case back in 1956 59 when distances of up to 12 000 miles were covered TV DX ers will also experience chances for re ception of TV stations from Europe Shortwave listeners will find less crowd ing on the shortwave broadcasting fre quencies as more stations move up to higher frequencies Not all users of the radio spectrum will benefit however The skip con ditions which have on occasion made a hash ou
153. extraordinary offer is intended to prove to you through your own experience that these very real advantages can be yours that it is possible to keep up with the literature published in your areas of interest and to save substantially while so doing As part of your Trial Membership you need pur chase as few as four books during the coming 1 months You would probably buy at least this many anyway without the substantial savings offered through Club Membership To start your Membership on these attractive terms simply fill out and mail the coupon today You will receive the 4 books of your choice for IG day inspection YOU NEED SEND NO MONEY If you re not delighted return the books within 10 days and your Trial Membership will be cancelled without cost or obligation ELECTRONICS BOOK CLUB Blue Ridge Summit Pa 17214 take any An Extraordinary Offer to introduce you to the benefits of Membership in ELECTRONICS BOOK CLUB of these 22 unique electronics books r Design Handbook 17 95 1054 238 p The Antenna RE c Construeticn Handbook tor amp SWL 9 95 1028 270 p How to Repair S Video Games 9 95 J n 919 434 p Color TV Trouble Factbook 9 95 E 811 280 p The Complete Handbook d ot Videocassette Reconders 9 95 1088 322 p lilustrated Dictionary of Microcomputer Terminology 12 95 800 602 p Master Handbook ot 1
154. features TV and radio tubes You can also find almost anything in electronics 322 Radio Shack s 1979 catalog colorfully illus trates their complete range of kit and wired prod ucts for electronics enthusiasts CB ham SWL hi f1 aynerimanter kite batteries toole tubes wire Classified MARKET ELEMENTARY ELECTRON CS is published Bi monthly The rate per word for CLASSIFIED ADVERTISEMENTS is 1 30 payable in advance minimum ad 15 00 Capitalized words 40 per word additional ADDITIONAL INCOME MECHANICALLY INCLINED INDIVIDUALS WANTED ASSEMBLE ELECTRONIC DEVICES IN YOUR HOME Get started in spare t me Experi ence Knowledge or Investment Not Necessary pect big profits 300 600 Wk Possible Write for free literature telling how Electronic Development Lab Box 1535E Pinellas Park FL 33565 NO experlence earn 53 per day at home guaran teed Newsletter 1 00 Spirit Delight 97 23 100 Street Dept 4 Queens NY 11416 200 WEEKLY BECOME COMMISSION MAILER KRED GRAHAMS DPBX 99371 TACOMA A 98499 ACCOUNTING amp TAX SERVICE CUT YOUR INCOME TAX Amazing report re veals 20 money saving secrets 1 00 refundable John Matson 256 EE 1 South Robertson Beverly Hils California 90211 AUTHOR S SERVICE PUBLISH YOUR BOOK Join our successful au thors Publicity advertising beautiful books All sub jects invited Send for fact filled booklet and fr
155. for substitute or replacement H D Scoregal P O Box 705 Douglas AK 99824 A U S Army frequency deviation meter test unit 1 86 A manufactured by needs any and all information Greg Ames 3017 Glenwood Pk Erie PA 16508 E ELEMENTARY ELECTRONICS January February 1979 ANIXTE MARK heliuhip The standard of excellence in CB Antennas THE BROAD STICK is the first totally new concept in top loaded CB antenna design In 1957 Anixter Mark originated the industry standard the Heliwhip Now a new industry standard THE BROAD STICK Designed for maximum power output and input THE BROAD STICK has been tested up to 700 watts and provides constant VSWR across 40 channels high operating efficiency because it s wound with 32 7 8 wave length of heavy gauge wire separate loading and matching coils and much much more THE BROAD STICK It s all new from ANIXTER MARK and it s a beaut It s Rugged It s Broad It s the Superstar Antenna Because it s tested Constant VSWR up to 700 Watts Across 40 Channels And no matter what your communication needs there s an ANIXTER MARK antenna or accessory engineered for you Here are just a few examples E EZ EZ 3 pa e nme dovi zi Heavy Duty EMEN Mirror at Heavy duty aluminum mount with CB Antenna Adaptor 22 gripping teeth In both pieces bites Used for upgrading to a higher per lt through paint for good ground con
156. ful in re moving it A hand held motor tool with a round wire brush will also do a good job You may want to paint the metal parts with chrome or aluminum paint to hide the damage After the chassis is clean pay special attention to the line cord If it has hardened brok en frayed or in any way is unsafe re place it If the set is very old i e made before 1930 it probably had a silk covered line cord Most electric Continued on page 86 ELEMENTARY ELECTRONICS January February 1979 Keep your projects cool calm and under control with this peppy power supply lated DC power supply which is sure to be a welcome addition to any workbench provided some family mem ber doesn t appropriate the power sup ply for use as a universal AC adaptor Compactly assembled in an eye catching low profile the Mini Reg is continu ously adjustable from 3 4 volts to 15 volts DC and delivers up to 500 milli amperes enough for just about any job Using the HEP C6049R precision monolithic IC regulator the Mini Reg effects 0 01 regulation with line volt age variations 0 05 regulation for load variations and its output imped ance is a mere 35 milliohms Short circuit proofed the Mini Reg also features adjustable current limiting which greatly reduces the chances of damaging valuable components in the circuits you are working on You can also use the Mini Reg as a constant Current source and recharge nicad bat teries
157. g TMS 9900 and Intel 8080 microprocessor programs and a number of general programmer aids covering base conversions and logical arithmetic operations The Programmer s Aid Pak ette is a 64 page booklet providing docu mentation for six full length programs EBCDIC Code Converter ASCI Code Converter ASCII and ABCDIC Encoder TMS 9900 Disassembler Intel 8080 Dis assembler and Programmer Simula tor All require a TI 59 with attached PC 100A thermal printer plus blank 59 magnetic program cards Pakettes are ryued S9 amiab also available on securities statistical testing civil engineering electronic en gineering blackbody radiation oil gas energy astrology and TI59 PC 100A printer utilities All Pakettes have a sug gested retail price of 10 plus 1 50 handling charge plus your state local taxes if ordering directly from Ti Circle number 74 on Reader Service Coupon ELEMENTARY ELECTRONICS January February 1979 U Lm es aR a Ka aT anl 5 aN an ol ee gd Sa RE R R EHE us Pam e Aa Tear For Fast Count Telco Products Corporation announces its new 7 digit LED Digital Frequency Counter the Count 500 which features large bright easy to read half inch high LED displays with polarizing lens Easily read under all lighting conditions Highly sensitive input accounts for its capabil ity to pick up and display low power CIRC
158. he diameter of the earth Sunspots are also the centers of The Sun s energetic atmosphere reaches far beyond the area of its visible disc as this Skylab coronagraph graphically demonstrates powerful magnetic fields although the process which causes these is not yet fully understood Astronomers have long noted the tendency for sunspots to join together into groups In 1849 the Swiss astron omer Wolf developed the concept of the relative sunspot number to keep track of solar activity The method took into account both the number of in dividual sunspots and the number of sunspct groups Wolf s method with a few mincr revisions is still used today Continued on page 87 COMPARISON OF SUNSPOT CYCLE MAXIMA IN THIS SUNSPOT NUMBERS N Q 1907 EIE 1928 1939 CENTURY N o s ui yp w c P P A 4 Ea A nd AKA W KONAK A A V T 1 L 196 9 1980 PREDICTED S47 1958 The amount of sunspot activity appears to be increasing according to this chart The peaks occur at about 11 year intervals but this varies enough to be statistically significant ELEMENTARY ELECTRONICS January February 1979 35 Train with NTS for the MicroComputers digital The world of electronics is daily becoming more challenging Technology is growing more specialized and the importance of digital systems increases every day
159. he four input lines of the BCD to seven segment decoder The outputs are all at zero until a single pulse appears on the input line Then one of the outputs changes to a one so that the BCD to Seven Segment de coder receives the number 0001 and lights segments b and c On the second pulse the decade counter sends out the number 0010 and a 2 lights up on the display This continues until the decade counter gets to nine it then re cycles to zero You should congratulate yourself you now have a practical event counter that will total up to nine the number of pulses generated by the occurrence of some event A switch on a refrig erator door that will turn on once each time the door is opened might allow you to record how many times it has been opened Unfortunately there is a phenomenon of mechanical switches called contact bounce where switch closing can trigger 3 or 4 pulses 62 This can be eliminated by adding a one shot multivibrator or similar cir cuit to clean up the unwanted pulses For the demonstration circuit the event pulses were obtained from a free running multivibrator signal generator for simplicity and freedom from un wanted pulses Extra Digits Now it is time to add a few more digits After all h w many useful things can be measured by a single digit To do this we must add a second set of the three components al ready mentioned a numeric display a BCD to Seven Segment Decoder a
160. he jumper on the insulation side of the board and install and solder T42 1 micro clips Vector on the copper side at all resistor and board take off terminals Clip a small heatsink Radio Shack 276 001 on the leads of QI when soldering Install re maining circuit board components ex cepting trim resistor RS Using 6 32 machine screws bolt IC1 and the heat sink to the cover plate Place a lock washer and two 6 32 nuts on each mounting bolt Omit the mica washer between ICI and the heatsink and ap ply a bit of silicone heatsink grease be Vout Volts dc 200 300 400 500 lout ma This chart shows the operating range of the Mini Reg at various line voltages The full 15 VDC is only available at lower currents but few IC projects ever require that much voltage or current supply 43 a MINI REG tween ICI and the heatsink Coil a 1 4 by 1 2 inch strip of fishpaper insulation and slip it down into the hole in the cover plate around the IC lead wires Push the PC board assembly down on the mounting screws and mate with the protruding IC leads and secure If you can t install the assembly look for bent pins or reversed installation of ICI Install switches S1 and S2 along with jacks J and J2 on the left side of the case Install diode D2 and capacitor C7 on switches S2 Secure two solder lugs on each binding post and install diode Di and capacitor C6 on the binding posts
161. held two meter transceiver Features 8 channel simplex with 600 kHz offset using one crystal per chan nel minimum 2 watts out and 0 5 aV sensitivity for 20 dB quieting Includes built in antenna nickel cadmium bat teries and battery charger An optional tone encoder and other accessories are also available Units will be available in January subject to FCC approval Battery Opwated Portable Timing Light Operates on its own re chargeable batteries for safety convenience and complete portability Ideal for use on boats or other vehicles where battery may be inaccessible Also fea tures dual range tachometer rugged pistol grip extra bright xenon tube for easy to see timing flashes WHi4line ms r Printer for M Hard Copy 4 Computer Readout Low cost microprocessor controiled line printer is designed to give you a con venient hard copy printout of your computer programming It eliminates losing and recalling program lines after they have scrolled off a CRT it also pro vides handy printed lists of address lines lists or other program data for easy editing and manipulation Prints the standard 96 character ASCII set upper AND lower case on a 5x7 dot matrix print head Designed for use with Heathkit computers and others as well Available fully assembled and tested only Low Cost Dual Trace Oscilloscope Low priced dual trace scope ideal for audio and TV servicing Features o
162. hooting Tester that comes with the Kit is reality swell and finds the trouble if therb is any to be found SOLID STATE Today an electronies technician or hobbyist re quires a knowledge of solid state as wall as vacuum tube circuitry The Edu KIt course teaches both You will bulid vacuum tube 100 solid state and combination hybrid circuits Progressive Edu Kits Inc 1189 Broadway Dept 594 Hewlett N Y 11557 ae ee re mm Nae E E Hewlett N Y 11557 Please rush me free literature describing the Progressive Radio TV Course with Edu Kits No Salesman will call CIRCLE 18 ON READER SERVICE COUPON emos ONE MAN ELECTRONIC FACTORY Investment unnecessary knowledge not required sales handled by professionals Postcard brings facts about this unusual opportunity Write today Barta EN Box 248 Walnut Creek CA 94507 wro McGEE S BIG SPEAKER CATALOG 1001 BARGAINS IN SPEAKERS PARTS TUBES HIGH FIDELITY COMPONENTS RECORD CHANGERS Tape Recorders Kits Everything in Electronics 1901 McGee Street Kansas City Missouri 64108 AUDIO amp ANALOG EXPERIMENTERS emusic synthesis stuff ideas equality parts e circuit theory eplans e electronic equipment send 25 or samp y r OUR Latest FREE H OF DIMES THIS SPACE CONTRIBUTED BY THE PUBLISHER Project Boards 1 was wondering where I could get the printed circuit bo
163. hout phone ringing Anyone with Ihis capability would breathe a sign of rehet while away hearing the familiar sounds of appliances and other systems properly operating SNP2 PLANS 7 00 SNP2K ALL PARTS FOR ABOVE 49 50 SNP20 ASSEMBLED amp TESTED 79 50 LONG RANGE XMTR PLANS 6 00 SEE IN THE DARK PLANS 5 00 DIRECTIONAL SHOTGUN MIKE PLANS 6 00 SUPER SENSITIVE PARABOLIC MIKE PLANS 6 00 SOUND amp TELEPHONE OPERATED TAPE RECORDER 5 00 CATALOG ON PLANS KITS amp FINISHED UNITS 1 00 Send check pr money order to SCIENTIFIC SYSTEMS Dept A10 Box 716 AMHERST N H 03031 CIRCLE 14 ON READER SERVICE COUPON eme wW ver POLY PAKS E SALE LED WATCH GUTS 1 95 Ei for Factory lay arounds work Who knows digital techniciana The compiete guts are there with black plastic case and 7 SEGMENT READOUTS Do they micro bonanza HOURS Cat No 267 leatherette band 6 functions MINUTES SECONDS MONTH DATE Sorry no speca Wt 2 n1 and ONE CENT SALE 3 DIGIT LCD WRISTWATCH DISPLAY 3960 3 tor 1 19 for 1 20 SPERRY FLAT NIXIES orange 3 dual digit 024 3for 1 19 for 1 20 SPERRY FLAT WIXIES orange 3 1 dig 015 31or 1 19 6 1 20 s MAN 3 BUBBLE READOUT 19 red com cath 3338 6 fer 1 00 121or 1 01 d D M N 4 READOUTS bubbis rsd com snode 19 150
164. hy 1 was operating legally on CB in 1954 How old is CB D Q Chicago IL CB as we know it on 27 MHZ was ini tiated in fall of 1958 It was Class D CB There were three other classes of which one was for RC So happy 20th Anniver sary ol Class D CB which is the mobile radio service we know so well Lend a Hand Boys A Here we go doing the sort of thing we do best helping others Pitch in and lend a hand whenever and wherever you can A Approved Electronic Instrument Corp Model A 100 RF signal generator needs owner s manual David Wozniak 14908 Richfield Livonia MI 48154 A RCA Model 8K 530 kHz 22 3 MHz receiver needs power transformer Rick Birtchet 8605 Meadow Br ok Lane Nor folk VA 23503 A Grundig Majestic Musical Instrument Model 8080 radio need schematic dia gram and volume control Stephen D Stoltfus R D 2 Lomestone Rd Parkes burg PA 19365 A EMC Model 208 tube checker needs operator s manual Bruce C Pierce Jr Star Route Ginger Bread House Rich landtown PA 18955 A RF Communications Assoc Inc Re mote Control Transceiver Model SB 6MR need schematic diagram and operating manual Bob Ruppe 4176 Pomeroy Ave Drayton Plains MI 48020 A Radio Shack Micronta 3 way CB Tester Meter urgently needs schematic diagram Adam Kaletski 59 Lorelei Rd West Or ange NJ 07052 A Zenith Model 6GO38R _ table radio needs battery pack Z 884 want plans
165. icated Each chan nel s counter can be individually erased so it starts from zero whenever desired Other channel counters are not affected by a counter erase Pressing count a second time restores the frequency in dication and the counter works un seen The signal on any channel can be used to control an associated recorder or other device through the aux function Pressing the aux and E for enter buttons programs any channel for remote control through a closed circuit providing up to 500 mA As soon as a signal breaks the squelch the aux control circuit is closed It is nor mally capable of handling the remote start circuit of a portable cassette re corder For a higher power control de vice an intermediate relay or transistor switch must be used The aux function is indicated by a small dot in the lower right of the L E D display Goodby Birdies One of the prob lems with some digitally synthesized scanners in the past has been birdies unwanted signals generated by the scanners internal oscillators The search mode often picked up some of these unwanted signals and locked the scanning onto the birdie because as far as the receiver is concerned the birdie is a legitimate unmodulated car rier In the Bearcat 250 however the user programs the birdies out first by disconnecting the antenna and making one search pass storing the birdie fre 76 playback from the TELESCOPIC WHIP AUX SWI
166. ics offers an Electronic Chemical Handbook for engineers and technicians It is a problem solver with detailed descriptions uses 330 There are nearly 400 electronics kits in Heath s 7364 If you re a component buyer or specifier you ll new catalog Virtually every do it yourself interest is included TV radios stereo and 4 channel hi fi hobby computers etc 331 E F Johnson has a CB 2 way radio catalog to help you select equipment for your vacation busi ness travel or normal day to day bucking the 332 If you want courses in assembling your own TV kits National Schools has 10 from which to choose There is a plan for Gls 333 Get the new free catalog from Howard W Sams t describes 100 s of books for hobbyists and technicians books on projects basic elec tronics and related subjects 335 The latest edition of the TAB BOOKS catalog describes over 450 books on CB electronics broad casting do it yourself hobby radio TV hi fi and CB and TV servicing 338 Break Break a booklet which came into existence at the request of hundreds of CBers con tains real life stories of incidents taking place on America s highways and byways Compiled by the Shakespeare Company it is available on a first come first serve basis 342 Royce Electronics has a new 1979 full line product catalog The 40 page full color catalog contains their entire new line of 40 channel AM and SSB CB transceivers hand
167. iffer ence between V in plus and V out which in turn depends on transformer T1 volt age When you are not using a meter at jacks JI and J2 close S2 The adjustable current limiting fea ture of the Mini Reg greatly reduces the chances of damaging circuit components of the circuit powered by the supply Suppose you are experimenting with a transistorized circuit drawing five milli amperes at five volts You would then set S2 to ten milliamperes At these set tings the maximum power the supply can deliver is but a mere fifty milliwatts If you plug a transistor in backwards the most it can draw is fifty milliwatts VIN S3 ROTOR BP i OIO RII RII R6 R7 ETC BP2 The parts should be placed according to this diagram Note the location of the three drill holes for securing the IC and the board to the chassis Locate the IC mounting holes very carefully so that everything mates snugly This will help keep the chip cool probably much less hence the device will survive the error However certain semiconductors can be damaged with but microwatts of power Nevertheless you are far better off using current limiting supplies If your experimental ICI HEP C6049R ELEMENTARY ELECTRONICS January February 1979 circuit draws 400 milliamperes at five volts set S3 to 500 milliamperes limiting the power to 2 5 watts This power level is more than enough
168. ike You get a decoder for re cording superb Dolby FM stereo And you get simultaneous listening en joyment of the decoded broadcast on receivers with tape monitoring The Realistic SCT 30 has dou ble Dolby About 380 PS Supertape Gold To go with 3 heads 2 capstans and double Dolby you need a cas sette tape that will en hance not degrade performance That s why we design and manufac d n p West Realist ic Tt mv Dolby Why 3 heads are better than 2 Why 2 capstans are better than 1 is better than single ture Supertape Gold in our own Fort Worth fac tory Like SCT 30 it s a playmate you can believe in at a price you Can afford Why Realistic Because Radio Shack has delivered quality audio at sensible prices since 1921 its Realistic tape and re corder line can point to over 5 000 000 customers as living proof of these claims Add after sale service that isn t lip service Add in house en gineering and manufac turing of much of the Realistic line And add _ the convenience of es 3 neighborhood sound where you get Nd sex talk from a specia 4 SN Fi pre Rad 10 Shaek The nationwide supermarket of sound Radio Shack is a Division of Tandy Corporation Fort Worth TX 76102 Over 7000 locations in nine countries
169. il lot more if you re reading BACKPACKING JOURNAL the newest outdoor publica tion by the publishers of CAMPING JOURNAL Order your subscription today BACKPACKING JOURNAL 1855 GPO New York NY 10001 Enclosed is 3 97 includes shipping and postage for 5 quarterly issues of BACKPACK ING JOURNAL All other countries add 4 82 Name Address A H A MMMM M City State Zi g8LOOO ELEMENTARY ELECTRONICS DIGI KEY 1 300 346 5144 CORPORATION ur 6 5 1 44 Quality Electronic Companents FREE 218 481 6674 o 12 5 s RESISTORS e TRANSISTORS x CAPACITORS e DIODES 1 C SOCKETS amp PINS e SWITCHES CLOCK MODULES OPTOELECTRONICS o BREAD BOADING amp TESTING DEVICES e DRAFTING SUPPLIES DATA BOOKS HEAT SINKS WIRE e TOOLS AND WRITE FOR FREE CATALOG E v ADAM OSBORN MICROPROCISSOR 80085 V 9 Trouble free Module 5M 451002 CLOCK MODULI BY NATIONAL StMECONDUCTOR a ET aa TUR 1 DON T FORGET OUR DISCOUNTS WHEN COMPARING PRICES INTEGRATED CIRCUITS E M fe Di pt S 270 Swivel Mount plac i 5 Ta e M aS Inlaid Woinut Chrome ien w e Trim Berelt H KT e EE e Ideal for Car Von KC ov Ove of 2 C 10 55C aN 4 or Boot AN ATTRACTIVE IMLAID WALNUT amp
170. ill back in the hobbyist stone age of meters and light bulbs Do your projects look like ZOth Century state of the art or do they look more like a turn of the century patent application If you think it is time to go digital but feel that the technology is beyond your grasp you are not alone There is a mumbo jumbo that has grown up around digital electronics that makes people think they have to learn all about computers before they can do any kind of digital project If you have ever made the mistake of asking a computer know it all how digital number displays work you are sure to have received a two hour lecture on binary numbers Boolean algebra and assorted flip flops and come away knowing fess than when you started Learn Backwards All this hassle is unnecessary however 1 you learn dig ital electronics backwards Start with the familiar end result a decimal num ber display and work backwards into D NUMBERS they are every the circuitry that makes it possible Digital displays come in a number oof different forms but all the circuits discussed here will use a common cathode seven segment LED Light Emitting Diode numeric display These are cheap easily obtainable and the circuitry can be adapted to other types especially the liquid crystal type displays The best way to learn about numeric displays is to put one together so you can physically see how it works and how the various components in terac
171. ing spikes on walls and ceiling reduce interior surface s overall reflectivity According to GM engineers impor tance of electromagnetic compatibility testing will increase as electronic con tent of products increases Electro magnetic energy from AM and FM radio transmitters radar mobile radios medical apparatus and other sources can upset electronic controls E ELEMENTARY ELECTRONICS January February 1979 BUILD 20 RADIO 75 and Electronics Circuits PROGRESSIVE HOME RADIO T V COURSE Now Includes 12 RECEIVERS 3 TRANSMITTERS SQ WAVE GENERATOR SIGNAL TRACER AMPLIFIER 5 SIGNAL INJECTOR CODE OSCILLATOR YOU DON T HAVE TO SPEND HUNDREDS OF DOLLARS FOR A RADIO COURSE The Edu Kit offers you an outstanding PRACTICAL HOME RADIO COURSE at a rock bottom Price Our Kit is designed to train Radio amp Electronics Technicians making use of the most modern methods of home training You will learn radio theory construc tion Practice and servicing THIS IS A COMPLETE RADIO COURSE IN EVERY DETAIL You will learn how to build radios using regular schematics how to wire and soiden in a professional manner how to service radios You will work with the standard type of Punched metal chassis as well as the latest development of Printed Circuit chassis You will learn the basic principtes of radio You will construct study and work with RF and AF amplifiers and osciilators detectors rectifiers
172. int bus strips The EXP 325 has CSC s tongue and groove edge t M Iu ttti ane gt ARBRE anen are an an p aes OBER P CIRCLE 62 ON READER SERVICE COUPON construction which also permits the at tachment of a small front panel plas tic or metal sheet to hold controls indi cators or other oversize components The suggested resale price for the EXP 325 is 2 75 For additional information con Continued on page 12 ELEMENTARY ELECTRONICS January February 1979 New customized look Mode M 500 sidebody mount top loaded fiber glass whip with super performance For over a quarter century buy ng the v2ry best CB antenna has meart buying Antenna Specialists From superior materials like resilient 17 7 PH stainless steel whips to superior engineering like the cool running coil in the famous Big Momma these are the finest antennas money can buy Only now you can buy them for less Because your Antenna Specialists dealer is offering big 25th Anniversary savings on over a dozen of our newest and most popular models It s a silver opportunity to move up to the stripes of quality SO see your dealer today the antenna specialists co d a member of The Allen Group Inc 12435 Euclio Ave Cleveland Ohio 44106 Export 220C Shames Drive Westbury L 1 NewYork 11590 4 Canada Simmonds amp S
173. ions If a current carrying coil is mounted on pivots and placed be tween poles of a strong permanent magnet the current flowing through 74 This Jewel voltmeter is mounted inan old cigar box These boxes can sometimes be found at flea markets but they are rare the coil will cause it to rotate A point er mounted on the moving coil will then move across a calibrated dial scale and indicate the amount of current flowing in the coil As mentioned pre viously resistors placed in series with a milliameter will make it a voltmeter The meter shown in the cigar box had a dial scale calibrated to read 10 and 250 volts full scale Since the meter re A simple three range voltmeter can be made by constructing the above Circuit from parts in your antique junk box The front panel of the Carrier Current Re ceiver looks almost like an old time ama teur radio transmitter Really a classic Inside the Carrier Current receiver there aren t many parts to cause trouble Main taining this set would have been simple quired one milliamp 001 ampere to deflect full scale one resistor should be 10 000 ohms and the other 25 000 ohms by ohms law we learned that volts divided by amperes equals ohms is 10 by 001 10 000 for one re sistor and 250 by 001 25 000 ohms for the other resistor In the circuit shown separate binding posts are used for each range If you want to build an old type voltmet
174. it has been Carefulsy designed step by step so that you cannot make a mistake The Edu Kit allows you to teach yourself at your own rate No instructor is necessary business or a job witb a future you will find the Edu Kit a worth while investment Many thousands of individuals of all PROGRESSIVE TEACHING METHOD The Frogressive Radio Edu Kit is the foremost educational radio kit in the world and is universally accepted as the standard in the of electronics training The Edu Kit uses the modern educational peirfcipie of Learn by Doing Therefore you construct learn Schematics study theory Practice trouble shootiiig all in a closeiy integrated pro gram designed to provide an eaStiy rearned thorough and interesting background in radio You begin by examining the various radio parts of the Edu Kit You then learn the function theory and wiring of these parts Then you build a simple radio With this first set you will enjoy listening to regular broadcast Stations learn theory Practice testing and trouble shooting Then you build a more advanced radio learn more advanced theory and techniques Gradually in a progressive manner and at your own rate you will find yourseif constructing more advanced multi tube radio Circuits and doing work like a professional Radio Technician included in the Edu Kit course are Receiver Transmitter Code Oscillator Signal Tracer
175. itter in the antenna line The high pass filter will pass fre quencies higher than 54 MHz the lower edge of channel 2 The high pass fil ter is mounted in the TV set as close to the VHF tuner antenna input as pos sible 66 CIRCLE 27 ON READER SERVICE COUPON sumar H The DenTron Super Tuner tunes every type of antenna between 10 and 160 meters The 1 kw version goes for 130 00 and the 3 kw version for 230 00 Other DenTron tuners have built in wattmeters and SWR meters along with antenna switchers helpful features if space in your shack is at a premium The top of the line model MT 3000A includes a built in dummy load for off the air transmitter tuning and it retails for 350 00 A word of advice is in order Don t offer to acquire or install high pass fil ters on your neighbor s TV sets In variably you will be accused of causing the set s breakdown whenever it fails in the next six or twelve months Television manufacturers will usual ly supply high pass filters free of charge to those customers requesting them Have your neighbor write to the manufacturers corporate headquarters see the instruction manual and in clude the information off the service data label affixed somewhere in or on the rear of the set Include a state ment f the problem Connecting the Equipment In or der and as necessary the items con nected to the back of the transmitter should be 1 the low pass TVI filter 2
176. ks are recom mended for IC1 and Q3 either com mercial or homemade from a scrap of metal The optimum value for R28 depends on the particular transistors used for Q2 and Q3 and on the speaker You will want to determine its optimum value as described later so do not install R28 at this time in its place temporarily wire a 100 K pot in series with a 10 K fixed resistor Set the pot approximately at midrange After assembling the PC board check carefully for solder bridges bad connections etc The PC board may be mounted to the chassis or cabinet by means of six sets of screws and spacers at the location indicated near its edges Arrangement of the components off STAGE I PIN OF ICS STAGE 2 Bz PIN IS OF IC5 STAGE 3 PIN 14 OF ICS OUTPUT OF FLIP FLOP PIN 3 OF IC4 ALSO LOAD ENABLE INPUT OF SR COMMON LINE FROM ANLG 505 _ _ aj HS bsc LI JL ud a oda Sp WES d A K 20 ores L4 ius NA INE NUI on EOM LEON ee the PC board is not critical The au thors arrangement is shown in the photos Some of the connections from the PC board to these components are indicated by circles on the schematic diagram Letters within these circles also appear on the etching guide If you use the switch specified in the parts list for S3 you will need to make a simple modification to it The specified switch has a rotation stop which allows only eleven positions to be indexed
177. language like Basic is just a bit on the scary side Perhaps you have even read a textbook or two on Basic but have been lost in a maze of example programs for mortgage amorti zation depreciation plotting of func tions and so on It can be hard enough to learn a new language without further confusing the issue Just imagine if you had to learn French by studying treatsies from the Sorbonne College of Higher Mathematics There s an easier way to learn Basic A fun way First sit yourself down with a good introduction to the Basic language such as the book Basic by Albrecht Finkel and Brown published by John Wiley and Sons Inc 605 Third Ave New York N Y 10016 the first few chap ters of which were serialized in our November 1977 through March 1978 issues of ELEMENTARY ELECTRONICS Now to gain a deeper understanding of how to apply your knowledge of Basic to programming sit down with a few game programs Try to play both sides of the game the human s and the com puter s Flowcharting Fun At first stick to some of the less complex game pro grams If you can get a program which includes a flowchart so much the bet ter A flowchart may look complicated but it simplifies understanding ELEMENTARY ELECTRONICS January February 1979 c Start out by using flowcharts When you begin to design your own programs such familiarity will pay off Take a look at the flowchart and program which accompany
178. lanker ANL and Modula tion SWR meter mode Standard ac cessories include a microphone DC power cable A C power cord CIRCLE 85 ON READER SERVICE COUPON Receiver Section Test Input sensitivity 0 5 Adjacent channel rejection 69 dB AGC action 16 dB SSB opposite sideband rejection su 40 dB Input level for S9 meter indication Transmitter Section Test AM RF output 3 8 watts SSB RF output 12 watts P E P Modulation to 85 Relative sensitivity for 85 mod off to 45 dB Modulation limited to 100 yes Editorial Remarks The 142 GTL has a relative reading S meter jacks for P A and remote speakers L E D digital channel indicator S RF out put meter and Modulation SWR meter Lj e MOTOROLA ELECTROSCAN CR 520 159 95 Motorola Inc General Description A 40 channel AM remote transceiver for mobile operation Power supply is 12 to 13 8 CIRCLE 97 ON READER SERVICE COUPON VDC with negative ground Main transceiver package mounts behind dash under seat or in trunk All con trols on microphone There are microphone controls and switches for channel selection volume squelch local distance sensitivity and power on instant channel 9 selection Stand ard accessories include a microphone DC power cable installation kit No internal speaker Requires optional external speaker Receiver Section Test
179. lation to 85 yes Relative senstiivity for 85 TOC eae er ees ote oer mae 2 dB Modulation limited to 100 no Editorial Remarks The Veep has a relative reading S meter double con version jacks for P A and remote 77 J CB XCVR CHECKOUT speakers L E D diigtal channel indi cator S RF output meter Li e REALISTIC TRC 470 229 95 Radio Shack General Description An in dash 40 channel AM FM stereo radio and 40 channel AM transceiver for mobile operation Power supply is 12 to 13 8 VDC with negative ground There are front panel controls for channel selection volume squelch balance tone and AM FM tuning Switches for AM FM CB mono FM noise blanker ANL and Monitor while listening to radio Standard accessories include a microphone DC power cable stereo speaker cables and universal mounting kit CIRCLE 32 ON READER SERVICE COUPON Receiver Section Test Input sensitivity m 0 5 aV Adjacent channel rejection 70 dB AGC action 10 dB Transmitter Section Test AM RF output 3 6 watts Modulation to 85 yes Relative sensitivity for 85 mod 428 dB Modulation limited to 100 yes Editorial Remarks The TRC 470 has plug in speaker power wires and CB monitoring while listening to AM FM and an L E D digital channel indicator gt p TECHNOLOGY AM Cy meri a an O DOWN dil ams Te PETRA e CB INFORMATION CENTER CB Y
180. ll lock to the first channel on which a signal appears and will resume scanning when the sig mrn Eee UTERE 71 a KATHI S CAROUSEL nal goes off if the second switch is set to PRI If the second switch is set to IND the rig will remain tuned to the main channel and an alerting tone will sound about once every second if a sig nal appears on the secondary channel As soon as I hear signal that I want to work I flip the M SC S switch to lock the rig to the main or secondary channel The operating technique comes naturally after an hour or so of use and I assure you it s nowhere near as difficult as I may have made it sound In point of fact the unit works beauti fully and I really miss it when I go back to one of my single channel rigs As for performance it s first class all the way The receiver checked out with a 0 4 V sensitivity for 10 dB S N N signal plus noise to noise selectivity adjacent channel rejection was 63 dB and the AGC action was an outstanding 2 dB for a 100 dB variation in input signal level In plain terms it means that if you have the volume cranked wide open to hear a weak signal almost buried in the background noise level a powerful signal coming on the channel will sound just a little stronger It won t blast you out of your seat The transmitter delivered 3 5 watts RF output to a 50 ohm load Modula tion was limited to 100 and the sensi Switch the transceiver on a
181. lock out switches for by passing channels when desired The Bearcat Four Six is designed for user convenience with the CIRCLE 47 ON READER Rubber Ducky antenna and a belt clip as standard features Sensitivity is rated 1 microvolt or less on VHF 1 5 micro volt on UHF and the radio s audio power is a full 300 milliwatts A wire antenna is included for difficult reception condi tions The external antenna jack can also be used for plugging in mobile or base antennas for extended range reception A slide away compartment is provided CIRCLE 79 ON READER SERVICE COUPON for easy access and crystals can be plugged in in any sequence of frequency or band The suggested retail price of the new Bearcat Four Six is 169 95 Complete details on this new Bearcat Four Six hand held scanner are available from Bearcat scanner dealers or by writ ing to Electra Company P O Box 29243 Cumberland IN 46229 Mini Solderless Breadboard Smallest addition to the Continental Spe cialties Corporation Experimentor series of solderless breadboard sockets is their new Model EXP 325 a quarter length model featuring DIP standard 0 3 in cen ter channel spacing The quarter length reference is made by comparison with the original roughly dollar bill size EXP 300 The new EXP 325 1 86 in long by 2 1 in wide by in thick is about the size of a small cookie yet it affords two rows of 11 five point terminals each plus two ten po
182. m Pw ow Ei ta wore E 00 d 0 71524 jum oF 5 j TON t P gt w 44 wor H Ed oa n 14 te a mM 5 amp 31 en 4 agua e vel ad 240 8 ME Dluse a 98 Space 2754 1 xl 44 HEA 1 MATOOT AND 1010 ejes ema CLOCH MODULES 190 104 4 T 1 0 KT Atak ay 99 natn m wars HONO H 4 EDs Oui T EEL lt e el eE TT TTT anam x M x US 10 116 Tw Anwar SCRATCH RESTANT AND 1436 7 CUAMPD JL MINA TIS mT MG ADAPTERS AVACARE TO wer FY MOUNTIG AMD LRT PERPICT B aat eb MIR wT HED R FER a 100 amp RA OOF 49 4f 6 DPT FOR fadi at M Rrz2Eijis 74197 m LL 1 141 vanus Ian M wee M capaz mrana YU a dun VR CT C didnt aem Ca tidal TE 6 Di61 M8Y MEANS QUALITY PRODUCTS TOA Pitt WATE VOLUME DISCOUNTS a PREP AIO SOUP PING AND INSUSANCI ae oa 84250584 DPN 1 AD LONG wii ammi FER TEC N B N TRAE D as Ta s Qu Can LD AMT DACIA MAGTEND Capa FRATUEES Ansembird and Truri yet only 149 95 8 br aed ouh T pim s consecter pai Levy
183. m and the most advanced per sonal computer There s nothing else to buy to use it but add ons are easy to make The 32K of RAM can be expanded to a maximum of 630K RAM The mini floppy disk drive can be in creased to three drives or replaced with two standard size floppy disk drives Up to four more can be added to the one RS 232 interface port Other possible peripherals include a CRT terminal and printer Smarts Il offers a full 16 lines of 64 characters per line on a standard ASCII keyboard Color displays 7 by 9 characters can be created on a color TV screen along with action sounds The Smarts system includes games income tax bookkeeping inventory and educational programs Smarts Fundamentals is said to provide the natural first interface between man and machine for both business personal use because it provides all that is needed to reach the first level of comprehension Price 1 595 as shown Circle 45 on Reader Service Coupon Floppy Disk Kit Heath now offers a new H8 Floppy Disk System in kit form that is identical in features and specifi cations to the assembled and tested WH17 floppy disk made available earlier by the company The unit includes 102K Bytes of available storage area per disk a fully assembied Wangco Model 82 disk drive expandable to dual disk the interface disk controlled circuit board kit which plugs directly into the H8 mainframe and a self contained power su
184. mer induces a changing voltage in the secondary winding 2 The ratio of the primary voltage to the secondary voltage is the same as the ratio of the number of turns in the primary winding to the number of turns in the secondary winding 3 If a transformer steps up voltage it steps down cur rent and vice versa The power drawn by the pri mary winding is equal to the power dissipated in the Continued on page 85 ELEMENTARY ELECTRONICS January February 1979 f Ic cca SSE See L 124 a p The BASIC Cookbook 7 95 f 1019 406 p The Master Handbook S of Electrical Wiring 10 95 d n pe f UP 841 238 p Build Your Own Working Robot 8 95 1011 270 p How to Repair Movie amp Slide Projectors 12 95 3 D AMP OP AMP E 856 476 p Master Op Amp Appli zations Handbook 16 95 678 276 p Modern Commurics tions Switching Systems 517 98 874 392 p Master Handbook of Digital Logic Applications 12 95 M we send you your choice of 4 of these prac tical Ume and money saving books as part of an unusual offer of a Trial Membership in Elec tronics Book Club Here are quality hardbound volumes each especially designed to help you increase your know how earning power and enjoyment of elec tronics Whatever your interest in electronics you U find Electronics Book Club offers practical quality books that you can put to immediate use and benefit This
185. ming To discover unknown services or frequencies the receiver can be pro grammed to search any frequency range within a single band The search can be programmed to stop each time a station is detected so the user can listen to the signal to see if it s a worth while service to store in a main channel memory Or the scan can be used just to locate frequencies instead of stop ping on the station until the transmis 75 B vasa sion is over the search stores the work ing frequency in the 64 channel mem ory The user can then step through the memory one frequency at a time to de termine which frequencies were active or can step and hold in order to moni tor the signal Again any desired stored frequency can be entered into one of the 50 scan channels At the touch of a button marked priority channel 1 can be programmed as a priority channel so that regardless of the channel groups programmed for scanning the receiver will scan channel 1 for activity every two seconds Any frequency within the five bands can be programmed into channel 1 With the priority switch off channel 1 functions as any other channel If you re not certain which frequen cies are the hot ones in your area you can get a count on the number of transmissions by simply pressing a but ton marked count The indicated fre quency on the display turns off and the number of transmissions on that par ticular channel is ind
186. n Circulation Director Robert V Enlow Subscription Circulation Manager Eugene S Slawson Marketing Director James C Weakley President and Publisher Joel Davis Vice President and General Manager Leonard F Pinto Vice President and Treasurer Victor C Stabile KBP0681 ISSN 0013 595X ELEMENTARY ELECTRONICS is pub lished bi monthly by Davis Publica tions Inc Editorial and Executive of fices 380 Lexington Ave New York NY 10017 all subscription orders and mail regarding subscriptions should be sent to P O Box 2630 Greenwich CT 06835 In U S A and possessions one year subscription six issues 6 95 two year subscription 12 is sues 12 95 three years 18 issues 18 95 and four years 23 95 Else where add 1 00 postage for each year For change of address please advise 6 to 8 weeks before moving Send us your current mailing label with new address Advertising offices New York 380 Lexington Ave New York N Y 10017 212 557 9100 Chi cago 520 N Michigan Ave 312 527 0330 Los Angeles J E Publishers Rep Co 8732 Sunset Blvd 213 659 3810 Second class postage paid at New York NY and at additional mail ing office Copyright 1978 by Davis Publications Inc January February 1979 Volume 19 No 1 electronics X v CONSTRUCTION PROJECTS FOR HOME AND WORKBENCH 29 Rhythm amp Blues Box be your own computer music maker 40 Hi Amp Meters heavy currents a
187. n hour in your spare time Our self study CB radio repair course can prepare you for a career in electronics For more information call toll free 1 800 654 6785 write CB Radio Repair Course Inc Dept 108 531 N Ann Arbor kiahoma City OK 13127 DO IT YOURSELF REPAIR TV S ANYONE CAN Easy Guaranteed Free Details Publication Box 517Y Brea CA 92621 FREE Encyclopedia Winemaking Beermaking Sup plies Equipment Ingredients Vynox Industries Box E E 7498 Rochester NY 14615 BUILD YOUR OWN BUGGING DEVICE Quite small transmission to any FM radio Plans and parts list 2 00 or complete kit for beginners 16 95 Send to JRC Electronics Corp Box 711 C Glen Eliyn IL 60137 SPEAKER REPAIR Complete How to 24 Illustr amp tlons 2 Repair 2860 Park St Hono HI 96817 FOR anyone who wants the satisfaction and economy of repairing furnishing and maintaining the furniture in his home Send 1 50 to FURNITURE 380 Lexing ton Ave New York NY 10017 UM aii sno EDUCATION amp INSTRUCTION USED Courses Books Lists 25e SMITH S 124 Mariborough Salem MA 01970 GET INTO BROADCASTING Become DJ engineer Start your own station get free equipment records d S Broadcasting Box 130 GIE Paradise CA 95969 pon e M COLLEGE degree by mail via resume Education 256D South Robertson Beverly Hills CA 90211 p echter ratito c i eb SE LE
188. n the BCD to Seven segment decoder IC chip By carefully coordinating the count er reset to zero pulse and the latch pulse so that the latch freezes the count display a moment before the CIRCLE 62 ON READER SERVICE COUPON This is a simple one digit event counter It will count from zero to nine recycle to zero and start the count again The resistor added between the clock on the lower left and the decade counter is to lower the level of the input voltage peaks 220 ohms is fine counter resets we have a event per unit time display Synchronizing To get this proper synchronization of clock latch and re set a Johnson counter or decade counter divider is used In this chip there are 10 output pins that go high puts out a 5 volt pulse in a re peating sequence So for every 10 input pulses each pin goes high once one after the other If we control the latch with the pin that goes high on the first input pulse to the counter and then reset with the pin that goes high on the third input pulse we can control the display so that it will latch and reset at the proper time The pin that goes high on the second pulse isn t used be cause of pulse overlapping One slight problem with the output to the latch is that it needs to be in The clock sets the tim ing of the latch and reset In this circuit the latch holds the count eight clock puls es after the clock has reset so that the num ber on the display is only pr
189. nce C Now C s capacitance will be very small As an example consider that the capacitance between two closely spaced ELEMENTARY ELECTRONICS January February 1979 22 wires amounts to less than 40 pF per foot of wire Despite the small magnitude of capacitance C however it can result in the appearance of a noise voltage VN across the amp s input impedance We are in trouble if VN is a significant fraction of V s magnitude and the situation is hopeless if VN equals or exceeds V2 To see what determines the size of noise voltage VN note that current from generator Vi can flow in a com plete loop first through Roi then then through C and finally through RG2 and RIN back to source Vi Since Raz is effectively in parallel with RIN and since VN is developed across this parallel resistance combination we are interested in the equivalent parallel re sistance which we abbreviate as RG2 RIN Basically what we have here is a voltage divider Rai C and RG2 RIN across Vi The noise voltage caused by Vi will be increased by the follow ing factors 1 an increase in the mag nitude of Vi 2 an increase in the fre quency of Vi since C s impedance STOP STATIC drops at higher frequencies 3 a de crease in source to receiver distance because this increases C and 4 an increase in the equivalent parallel re sistance RG2 RIN Voltage and Frequency It is ap parent that high voltage high fr
190. nd a Decade Counter Everything is wired the same way except that the input for the second decade counter is attached to the carry out pin of the first coun ter This pin gives off an output pulse each time the counter resets from nine to zero So after the first display gets to nine and then resets the second display counts one so that the display reads ten When the decade counter resets a second time the display clicks to 20 An almost infinite number of digits could be added that would count once each time the preceeding stage re Set to zero A counter such as this could be used for any sort of tallying operation where you have to keep a record of how many events have taken place Most digital applications however involve rate operations cycles per second miles per hour gallons per day or even dollars per week Rate Measurements For the above counter to be converted to measure the number of events per unit of time a few additions have to be made The first of these is called a clock A clock LO O OGO This block diagram shows how the sequence of pulses at the input are figst translated to BCD and then to seven segment coding gives you the seconds of miles per second or the hour of inches per hour It sets the interval over which the num ber of events is counted This is achieved by adding a simple freerunning mul tivibrator In the case of the circuit shown it puts out five volts with mo mentary n
191. nd flip a switch marked M SC S to M for main and the main channel indicat or turns on to indicate the main or normal channel Flip switch to S for secondary and the secondary channel indicator turns on If the switch is set to SC Scan the transceiver will work on the main channel and sample the secondary channel approximately every second If a signal comes on the second ary channel its pres ence will be announc ed by a beeping alert tone or the transceiv er will lock to the sec ondary channel as de termined by the Alert selector switch VOLUME tivity for 85 modulation was 32 dB which was a pleasure to use in this age of super microphone sensitivity that picks up a pin dropping five blocks away The LM 300 has just enough mike gain to produce maximum talk power with a low voice level but not enough sensitivity so that every sound and creak from a car fifty feet down the road gets transmitted along with your RF GAIN SCAN SECONDARY S RF SELECTOR ALERT SWR M SC S CALIBRATE En i NOISE A SQUELCH AND BLANKER SECONDARY CB PA AND SWR CAL SENSITIVITY LIMITER DIMMER modulation As you can tell I m really impressed by the Lafayette LM 300 It s well thought out and priced right at 169 99 which includes the mike power cable and mobile mounting bracket For additional information on the LM 300 circle No 40 on the readers service coupon DJ
192. ng effectiveness increases with frequency Special magnetic alloys such as mu metal are necessary at low frequencies All things considered magnetic shield ing is more difficult than electric ELEMENTARY ELECTRONICS January February 1979 shielding Wiring Problems So far we ve dealt with stray pickup from a more or less familiar viewpoint familiar at least in the sense that whenever noise problems occur the first thing to be blamed is some mysterious invisible field Very often however the trouble is the han diwork of a more mundane villain your circuit s electrical wiring Figure 5 shows a serial power distri bution system the most common way of delivering power to the various stages of a piece of equipment Two power leads run from the supply to one stage and then from there to the next stage and so on Such a scheme is simple and generally practical except when you have the situation shown in Figure 5 Here we have a low level source Vs driving a high gain amp stage with resistor R and inductor L representing the resistance and induc tance of the interconnecting ground lead Current I from the high current stage and current 12 from the switch ing stage both flow through the power bus in particular through R and L Since the amp responds to the potential difference between its input and ground leads any voltage developed across R and L due to I and Iz appears in series with Vs and this noise volt
193. ng normal solder does but with only the heat of a match candle or a lighter needed to melt it Emer gency Multicore Solder comes in tape form You wrap a short length around the splice and heat it with a match until it melts and solders the joint One match is usually all you need Another nice thing about being in tape form is that you can keep a foot or two of it folded up in a credit card slot in your wallet Great for those unexpected emergencies Don t worry about bad joints the stuff works great In some situations it is a real temptation to use this even when the regular solder is easily avail able and there is absolutely no reason why you shouldn t One of the ELE MENTARY ELECTRONICS editors used it to repair a long heavy dipole ham radio antenna he says the antenna works better than ever To use Emergency Multicore Solder just strip and clean the wires and then twist the wires together for a good physical connection Next wrap a short length of the solder around the joint about two or three times Heat the connection with a match or better yet a butane gas lighter Emergency Multicore Solder comes in packets with 36 inches of solder for 89 cents Your best bet is to pick up a packet now before you regret not hav ing bought it For more information circle number 86 on the reader service coupon B ELEMENTARY ELECTRONICS January February 1979 rrr x TUTTA d a 5 2 ab 2o Leman Cane N d 4
194. ni Reg defective or improperly installed Q1 If your current limit is say seven mil liamperes you can bring it up to ten by using a smaller value for R10 or by connecting a suitably larger value re sistor across R10 Only after you have verified current limiting action at low current Set S3 to pick up R4 500 ma setting and set the VOM accordingly You will need either 50 ohm 10 watt rheostat or adjustable power resistor to gradually load the supply Or you can use a number of small valued power resistors Set the rheostat to maximum resistance and connect it across the output ter minals Gradually reduce load resistance while observing output voltage and cur Error Amp amp Output Stage Q1 9 Ica 0 Rsc E Vout power supply Thanks to such ICs construction projects are easy to build ELEMENTARY ELECTRONICS January February 1979 rent Current limiting should occur at below 500 ma To increase the limit to 500 milliamperes select and install a suitable resistor for R5 Proceed simi larly to size or trim resistors R6 thru R10 You can easily include other cur rent limits in the spare positions on S3 to match the charging currents of your nicad batteries Do not exceed 500 milliamperes ot else will be dam aged Application The operating range of the Mini Reg for several line voltages is shown The supply drop out shown in the upper right hand corner of this chart is due to an insufficient d
195. nt engine reaches this speed a warning light will tell the driver to let up on the gas pedal The unit comes with all the wiring and mounting hardware it can be glued or screw mounted to the top of the dashboard of most American and foreign cars Installation is easy thanks to the clear concise directions The tach is connected to the car s battery negative ground only and the sensor wire pass es through the firewall to the engine If there is no appropriate hole in the fire wall one will have to be drilled The sensor wire is wrapped counter clock wise around one of the spark plug cables If the readout is shakey or it tends to switch into the red line setting mode it helps to increase the number of sensor turns around the spark plug cable The entire installation should take about two hours Read the direc tions ahead of time so that you will know what tools are needed The Indy Cator Dual function Digi tal Tachometer retails for 59 95 If you would like more information about this interesting and useful product circle number 53 on the readers service cou pon or write to the manufacturer Digital Concepts 249 Route 46 Saddle Brook NJ 07662 ELEMENTARY ELECTRONICS January February 1979 m WHEN ALL THE CHOICES of hard ware and software have been made by the home user and the checkbooks have been balanced and air conditioners and lights put on a 24 hour schedule there is
196. o Any sequence of one to twelve beats with any of the individual beats accented is readily set POWER On to drive the rest of the circuitry The pulse rate which sets the tempo of the rhythm is controlled by Tempo pot The pulses from C2 pin 3 go to IC3A IC3A and IC3B both NOR gates are connected as a monostable one shot multivibrator which puts out a pulse each time it is triggered by a pulse from IC2 This pulse is then fed to NOR gates IC3C and IC3D to improve its shape and to generate both an inverted negative going pulse from pin 3 of IC3C and a positive going pulse from pin 4 of IC3D As we ll see these pulses serve as clock ing or simply clock pulses for the ELEMENTARY ELECTRONICS January February 1979 s 8 Boogie to the sound of this electronic drummer by Randall Kirschman flip flops in the synthesizer They oc cur at the same rate as the tempo pulses from IC2 but are narrower Shift Into High The next section on our itinerary is a shift register Basical ly a shift register is a string of flip flops connected in cascade The output of each flip flop is connected to the in put of the next and all are clocked by the same clock pulse Thus at each ELECTRONIC BHYTHM SYNTHESIZER A i C FF 12 SEQUENCE LENGTH clock pulse the high or low bit held in each flip flop is shifted to the next flip flop except at the end
197. o Suta tenza operates on a somewhat isolated frequency 5 095 kHz where most SWLs even with relatively inexpensive receivers with only average frequency readout abilities can find it From this point on most of the Colombian stations are commercial op erations heavy on the Latin sound when it comes to music There are a couple of dozen stations that can be tuned without great difficulty These are some of those which have been putting out decent signals in recent months Most of them can be heard during the evening hours Emisora Nuevo Mundo HJEU Bogota 4 755 kHz operates 24 hours a day Radio Guatapuri pur 4 815 kHz Radio Bucaramanga HJGF Bucara manga signs off at 0400 GMT 4 845 kHz Ondas del Meta Villavicen cio 4 885 kHz Emisora Meridiano 70 Arauca 4 925 kHz Radio Colosal HJHD Neiva 4 945 kHz 24 hours a day a good bet for all For those not familiar with Spanish pronunciation it is ko lo SAHL Radio Santa Fe HJAE Bogota 4 966 kHz another easily heard 24 hour per day station Radio Surcolombiana HJOX Neiva 5 010 kHz Radio Cinco HJOW Villavicencio 5 040 kHz beware several Latin stations use this frequency LA Voz del Llano HJIA Villa vicencio 6 115 kHz the name means Voice of the Plain and especially the early morning programming is HJVG Valledu HJJU directed to Colombias cattlemen and cowboys La Voz del Huila HJFR Neiva 6 150 k
198. ociated scanner and tone alert o M EE ee CIRCLE 40 ON READER SERVICE COUPON ELEMENTARY ELECTRONICS January February 1979 The LM 300 has two independent VCOs voltage controlled oscillators phase locked to a quartz oscilaltor Each VCO has its own channel selec tor and its own digital channel indica tor the primary channel indicator being red the secondary being green Under stand that the remainder is a single double conversion receiver What this means is that there are two oscillators which can be used to control the same receiver section The Lafayette engi neers have cleverly eliminated the need for separate receiver sections and addi tional unnecessary circuitry with an in genious front panel switching system Two switches determine the action of the VCOs One switch is labeled M SC S meaning main scan secondary The other switch is labled PRI and IND PRI meaning the unit auto matically switches to the channel con taining a signal and IND meaning an audible tone al rt when a signal is present on the secondary channel with the rig remaining tuned to the main channel If the switch is set to Main the rig is tuned to the main channel If the switch is set to S the rig is tuned to the secondary channel In the SC Scan position the rig is tuned to the main channel and the secondary channel is sampled scanned approximately once each second The rig wi
199. ocks the shift regis ter loading it and then clocks the D flip flop so its output goes ow put ting the shift register into the serial mode After that the Aigh in the shift register is clocked from stage to stage as described previously Move To Multiplexing Let s move on to the next section of the circuit to see why the Aigh is being shifted around The output of each stage of the shift register is fed to the control input of an analog switch in IC8 9 and 10 An analog switch is a solid state ver ELEMENTARY ELECTRONICS January February 1979 CONTROL NETS CONTROL A dla 100K 20 OOK EXAMPLE NUMBER RHYTHM 3 4 J J 2 2 8 TU v a IE R 4 6 8 4 Fa 5 7 8 J d 6 6 8 AUDIO OUTPUT enel To use your R amp B Box as a melody generator con struct one of these voltage controlled escillator circuits and connect it to jack 2 and to an audio amplifier Ne POT SETTINGS QQQO OOO OOOO 2 34 6 7 8 9 10 ft I2 Tate LENGTH 3 CXOQOQOOO0O0O000 SEQUENCE LENGTH 4 COO OO00000000 SEQUENCE LENGTH 9 SEQUENCE LENGTH 6 RARA SEQUENCE LENGTH 7 is ds J LLL L 45 6 7 9 10 II 12 SEQUENCE LENGTH 12 FULL ON C FULL OFF O Here are some examples of time signatures and their corresponding setups on the control panel Remember that not only is tempo controlled but also emphasis There aren t many m
200. of Merit and Discount Privileges You receive all parts tools instructions etc Everything is yours to keep PRINTED CIRCUITRY At no increase in price the Edu Ki t now includes Printed Circuitry You build 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 becoming popular in commercial radio and TV sets A Printed Circuit is a special insulated chassis on which has been deposited a con ducting material which takes the place of wiring The various parts are merely plugged in and soldered to terminals Printed Circuitry is the basis ef modern Automation Electronics A knowledge of this subject is a necessity today for anyone ine terested tn Electronics R GN CAR Gye 5 CHOSES STATE AR ZIP PROGRESSIVE EDU KITS INC 1189 Broadway Dept 594 DJ Reg 5 Training Electronics Technicians Since 1946 FREE EXTRAS SOLDERING IRON ELECTRONICS TESTER e PLIERS CUTTERS e VALUABLE DISCOUNT CARD e CERTIFICATE OF MERIT e TESTER INSTRUCTION MANUAL e HIGH FIDELITY GUIDE QUIZZES e TELEVISION BOOK e RADIO TROUBLE SHOOTING BOOK MEMBERSHIP IN RADIO TV CLUB CONSULTATION SERVICE e FCC AMATEUR LICENSE TRAINING PRINTED CIRCUITRY SERVICING
201. of the Reset Start pushbut 30 54 EER RII 51 TI J2 JI With the cover removed the placement of all components can be observed When wiring the front panel pots it s a good idea to tag the wires from the PC board for identification For more work room install only every other pot at first wire then install the rest CT ICA ICS 16 C8 R25 29 GI R28 ICIOY IC6 x r JE rrr 4 EE em R23 Q3 Q2 R24 CG RET ICJ IC5 R4 C5 RIOR9 C4 IC3 RI IC2 IC4 R7 RG R8 R2 RS CI ICI A neat clean professional printed circuit board can be made using the free template available from e e To obtain one send a stamped self addressed envelope to Rhythm amp Blues Box ELEMENTARY ELECTRONICS 380 Lexington Ave N Y NY 10017 ton switch S2 and the other half of 4 This half of IC4 is also a D type flip flop but is used here as a set reset flip flop or bistable latch to eliminate the effects of switch bounce from S2 Pushing S2 makes pin 6 of IC4 high setting the latch This in turn sets the other flip flop via pin 1 to pin 8 in IC4 which puts a high on the load enable input of the shift register pin 7 of ICS 6 and 7 putting it into the parallel mode At the same time the latch makes pin 4 of IC2 low stopping the tempo pulse to keep the synthesizer silent Releasing S2 makes pin 4 of IC4 high which resets the latch and IC2 and IC3 start producing pulses The initial pulse first cl
202. oing conferences games simulations and educational programs The use of a larger central computer as a mostly read only device would make possible the creation of a large public data base or community com puterized library Projects to realize many of these ideas already exist In the San Francisco Bay area a PCNET has been operating for more than a year In the Chicago area a computerized bulletin board has been established and is now doing a poll to see if people around the coun try are able to log onto the system and which enable them to read protected messages You can even whisper to someone clear across the table Perhaps it s better to call it electronic note passing Digital Broadcasting If it is possible to digitally encode an audio cassette tap the most popular mass storage medium for home computers then it can be no major problem to encode an FM radio carrier with the same information This is precisely what is being done on the San Francisco Penninsula by the Digi cast Project The hardware invest ment will be relatively simple the soft One common form of data transmission protocol which enables computers to understand each other is the packet The header contains the transmission coding necessary for the re ceiving computer to accept the incoming data The checksum verifies correct reception use it Readers owning computers with modems might wish to try 312 528 7141 When you hear
203. on you can get from these pro grams is worth the price Further each program has a list of suggested modifi cations and hints on how to achieve them The games are lively unique and ba played over and over again without being boring The Devil s Dungeon also from En gel Enterprises retails for 3 50 It con tains a very exciting program which is a switch on the usual computer laby rinth style of cave game You are placed in a many tiered underground cavern There are levels and levels of caves below you and each level is dif ferent and more challenging than the last There may be gold and treasure in a room along with evil creatures de mons and poison gas How well you do is based on your strategy your experi ence your strength and other variables It s an adventure that can easily con sume an afternoon A good overview of this field is of fered in the book Game Playing With Basic by Donald Spencer Hayden Book Company 50 Essex St Rochelle Park N J 07662 6 95 This book delves into the nuts and bolts of pro gramming using games as teaching de vices There is extensive treatment of flow charting as well as general hints and maxims concerning programming There are many game programs scat tered in the pages but this book is less concerned with presenting programs than teaching programming The last chapter of the book is en titled Games For Reader Solution The rules for twenty six
204. ong mounted on top of the chassis with three or more wires or 1 threaded stud on the bottom If the radio is from the 1930 s you had bet ter replace the filter capacitors as a form of insurance against early failure Other small capacitors should be re placed since most cardboard tube capa citors have leakage resistance and will cause the radio to play poorly or not at all While you are under the chassis look for burned resistors wire with hardened or broken insulation etc Use capacitors with the same capacity and with the same or higher working voltage Now when you plug in the radio you should hear a faint hum in the speaker When you rotate the volume control you should not hear a loud click static etc but only a rushing noise as you turn the control clock wise If you do get a loud Static noise the volume control is noisy or worn out The only permanent repair is to replace the control If you want to try cleaning it buy a can of contact cleaner at a radio parts store and follow their directions If your radio has no built in loop antenna you will need about 50 feet of wire connected to the antenna lead to pick up stations The ideal solution is to put up an outdoor an tenna A shorter piece of wire may SWITCHING CIRCUITRY LOW LEVEL CIRCUITRY bring in local stations Speaker Repair One more problem may be the speaker Look for holes and loose seams in the cone especially in the center around the voice
205. ons Ltd Stripes of Quakty CIRCLE 34 ON READER SERVICE COUPON 1978 The Shakespeare Co Style No 176 Big Stick CB base antenna 300 watts power rating DC ground 125 MPH wind rating 12 times more Capture area at 60 height B Conductor sealed in fiberglass m 18 height includes U bolts for mounting to 114 and 11 pipe accepts standard PL259 connector and 50 ohm cable Factory designed crimping permanently Malos for words Big Stick Antenna gets out when the skip gets thick With its unique design this antenna delivers the longest possible range the Strongest signal capture area and the lowest radiation angle of any omni directional antenna in its class Only two pieces Big Stick You can count on Big Stick s engineering for performance that ll keep you talking It s the one and only two piece antenna that s a cinch to install and trouble free 1 Stick has a band spread tuned circuit that yields a low SWR across all 40 channels See SWR chart 2 lts DC ground provision lowers static noise and reduces lightning hazard 3 Signal loss is prevented Dy its innovative polystyrene air cell dilectric structure 4 The silver plated copper braid in the decoupling sleeve lowers resistance and increases efficiency 5 The metal radiator is completely protected by a sheath of high grade fiberglass 6 Its aluminum mounting Sleeve includes U bol
206. ook is very nicely done and was written and published in Great Britain The book has 96 pages and is in a large format with large type and many pic tures all of sets made in Great Britain before 1946 There are 50 pages show ing crystal radios while the balance of the book covers AC operated radios Even though it was printed in England and shows English radios I believe that there is enough information in it to give American collectors their mon eys worth You may secure a copy by sending a check or money order for 9 95 for the book plus 50 cents for shipping to Antique Radio Press P O Box 42 Rossville IN 46920 G ge PROTECT YOUR VALUABLES 8 35wt 3 way 12 90wt NEW packaged system A super close out item Protects your valuables gun s CB s stereo equipment test equipment etc List Price 22 88 Sh Wtilb 8 10474 7 88 3 for 22 88 8 10474 22 88 3 Ultrasonic andy control was part of an Ad miral remote control package for color TM The original functions were On Off volume VHF UHF and channel select Receiver contains 3 relays and one four position stepping relay Also cludes a complete data pkg Control section operates on 115 VAC Good for toys garage door openers TV stereo systems or any of those STAR TREK ino vations you would like to make on your own Energize or de energi
207. oportional to the number of events per cycle rather than a total of the events verted This is accomplished by send ing the pulse by way of an inverter You can use a common inverter An inverter is a device that produces a high output with a low input and a low output from a high input Putting It All to Work You have now finished your basic rate measuring device Now it s up to you to incor porate all of this into your pet project All you have tc do is convert your project s output into series of pulses of high and low voltage high being about five volts and low about zero volts A high frequency of pulses will give a high numeric readout and a low frequency of pulses a low readout If your project gives a variable volt age readout you can buy a chip called a analog to digital converter this puts out a Dares of pisas in The CSC Proto Board made experimentation a snap Connections could be swapped around without muss or fuss Hang on to the data sheets that come with IC chips they are an invaluable reference source Some like the Radio Shack Archer ones shown here have lots of ideas for future experimentation and circuit design modifications ELEMENTARY ELECTRONICS January February 1979 63 a DIGITAL COUNTING proportion to an increase in voltage The chips used in this article were referred to by their general name rath er than number since the attached schematic is only an example of a
208. organ or multi oscillator synthesizer effects The master rank utilizes a volt age controlled clock to allow pitch bend ing vibrato two waveforms and per cussion effects The two slave ranks can each be synchronized to either the master clock or an alternate tunable clock The output amplifier allows vari able attack time and overdrive control Available footpedals and footswitches al low the musician to bend pitch up or down introduce vibrato or trilling and switch the slave ranks in and out Or gantua also features a unique octave footswitch capability which raises all ranks one octave Organtua is avail able in kit form or custom assembled by PAIA Kit price including PAIA s usual fully illustrated step by step assembly in structions and operating manual is 279 95 shipped freight collect For more info contact PAIA Electronics Inc 1020 W Wilshire Blvd Oklahoma City OK 73116 Incohol Aldicator From Palmetto International comes the Breth Alyzer the latest thing in personal electronics for the person who has or wants everything A pocket sized intoxi meter the Breath Alyzer will tell you ob jectively if you or a friend are in a safe 4 SERVICE COUPON condition to drive after drinking alcohol Scale shows intoxication degree from O 1 mg liter or less slightly drunk to 25 mg liter smashed Selling for 44 95 the Breath Alyzer comes with test vial of alcohol and attra
209. other hobby computer publications you ll note they are also switching entirely to direct copy of the programmer s listing Versatility As for the way programs are written the programs are meant to be used on as many computers as pos sible using as many versions of Basic as is possible though we must eliminate the integer Basics because they are too restrictive for electronic hobbyist use This means we cannot use functions features or cute tricks common to one particular version of Basic The only exception made is for Heathkit Extended Basic because programs using some of its special functions are very easily modified for other Basics such as we did with the LINE INPUT statement in an earlier program The SWTP Co version 2 0 Basic which is generally used for our pro grams is perhaps the best hobbyist Basic in terms of easy adaptation or direct use with computers having other ver sions of Basic We have found that as general rule if the program works with a simple construction in SWPT Co Basic it will work in any floating point Basic This month s program Gamble is a straight fun program that will help you determine the odds on a particular game or event It won t make you an other Nick The Greek nor should you mortgage the old homestead hoping you ll find the pot of gold at the end of the rainbow but it will allow you to challenge the officially approved Continued on page 98 ELEMENTARY ELECTRONIC
210. ou first thought You may want to do a complete re finishing job The original finish usually consisted of a coat of shading stain and one or two coats of clear lacquer If you want the natural color of the wood to come through you must remove the finish down to the bare wood Always follow the directions on the can of paint stripper you are using To remove the finish on our cabinet we used Treadways Paint and Varnish Re mover You can purchase a complete Treadways refinishing kit for 9 95 It 42 includes remover Tung oil finish steel wool brass brush and instructions for use Pour some of the remover into a bowl and dip the steel wool supplied into the remover Now rub with the steel wool and the finish will begin to come off the cabinet After the cabinet is stripped and washed clean sand it lightly with No 220 Garnet paper or extra fine sandpaper Wipe the cabinet with a tack rag to remove all traces of dust Now you are ready to put a new finish on the cabinet You can use the Tung oil that comes with the Treadway The finished product will be the pride of your showcase With a like new finish on the ventilated If the speaker grill cloth was ruined shop the fabric stores and Hi Fi shops for a suitable replacement Install the cloth in the cabinet replace the speaker and put back the escutcheon Now you are ready to restore the radio electrically Getting It Working About the first thing to do is to remove the
211. ou have the cool and want the training it takes to make sure that a sound blackout during a prime time TV show will be corrected in seconds then answer this ad You ll probably find CIE has a course that s just right for you At CIE we combine theory and practice You learn the best of both Learning clectronics is a lot more than memorizing a laundry list of facts about circuits and transis tors Electronics is interesting bc cause it s based on somc fairly recent scientific discoveries It s built on ideas So look for a program that starts with ideas and builds on them That s what happens with CIE s Auto Programmed Lessons Each lesson uses world famous programmed learning methods to teach you important principles You explore them master them com pletely before you start to apply them But beyond theory some of our courses come fully equipped with the electronics gear to actually let you perform hundreds of checking testing and analyzing projects In fact depending on the course you take you ll do most of the basic things professionals do every day things like servicing a beauty of a Zenith color TV set or studying a varicty of screen display patterns with the help ofa color bar gencrator Plus there s a professional quality oscilloscope you build and use to see and read the characteristic waveform patterns of electronic equipment You work with experi enced
212. ough another amplifier speaker an External Amplifier jack J3 and External Speaker jack J4 are provided Get into the swing of things with our Rhythm and Blues Box and be the most percussive constructionist who ever drummed up a storm ELEMENTARY ELECTRONICS January February 1979 How to subscribe to America s most M r HRE down to earth magazine for the electronics and radio hobbyist B Electronics Each issue brings you e fascinating electronic devices to build e Instructive articles on CB electronics shortwave and lively columns e a Basic Course in electronics theory e a great amp A column ta help with your projects or anything electrical ELEMENTARY ELECTRONICS Box 2630 Greenwich CT 06830 Bill me 3 98 for ONE YEAR 6 issues Enclosed is 3 98 Canada all other countries 5 69 Name please print Address Cure Ee E NK T 7 Allow 6 to 8 weeks for delivery of your first copy H8LO17 WHAT S THE NEWEST AND FRESHEST MOST HELPFUL MOST INFORMATIVE BACKPACKING JOURNAL is popular because it is the one magazine with something for everybody for the beginner intermedicte and expert alike h doesn t assume everyone has done the Appalachian Trail end to end or conquered Mt Everest But if Everest or something slightly less challenging is your cup of tea you ll be at home with BACKPACKING JOURNAL You ll enjoy the tra
213. ound on the same core This core can be laminated iron ferrite or air Through the principle of induction the alternating current flowing through the primary winding sets up an alternating magnetic field in the core This magnetic field in turn induces an alternating voltage in the secondary winding or windings In this way energy is transferred from the primary to the secondary A transformer that reduces the voltage in a circuit is called a step down transformer This is true for ex ample of a radio receiver filament transformer which steps the 117 volt main supply down to 6 3 volts A transformer that is used to increase the voltage in the circuit is known as a step up transformer An example is the high voltage transformer which pro duces the several thousand volts needed to operate a television picture tube The basic transformer has two windings primary and secondary wound on a laminated iron core The two windings are insulated from each other and from the core The primary winding is connected to the energy source and the secondary winding is connected to the load As alternating current flows through the primary a pulsating magnetic field is set up in the core As the constantly changing magnetic field cuts the turns of the secondary a voltage is induced in the secondary winding ELEMENTARY ELECTRONICS 1979 I FROM SOURCE T Ej PRIMARY SECONDARY WINDING WINDING The
214. ounder in a few hours The only annoyance is with the battery holder assembly The kit didn t include any kind of fastener to attach the four L shaped clips that make up the holder Pop rivets were the easiest solution but it did mean an ex tra trip to the hardware store All th parts fit on the perforated board as is indicated in the instructions but you should follow the recommenda tions to be careful with the spacing There isn t a whole lot of extra room on the board If you have trouble with perf board construction then you might consider ordering the optional printed circuit board For more information about Mutt Minder circle number 50 on the read ers service coupon It is availabie from Information Unlimited Amherst Pro fessional Building Box 716 Amherst NH 03031 for 29 50 in kit form and 44 50 fully assembled The printed circuit is available for 4 50 and bat teries can be ordered for 3 00 Re member Mutt Minder is not a toy but a device that will repel hostile dogs It is not to be abused ELEMENTARY ELECTRONICS January February 1979 by Gordon Sell DIGITAL NUMBERING m FOR THE HOBBYIST Teach your projects to talk back digitally where The entire electronics world has been caughtrup in the digital revolution watches radios TVs VOMs frequency counters the list is almost endless But have your con struction projects been a part of the revolution or are you st
215. pply The storage media is the expanded 40 track seek time and a typical random sector access time is less than 250 milliseconds for the new unit The operating system software for the H8 H17 Floppy Disk System is available and designated H8 17 This software includes the Heath Disk Operating System HDOS with diagnostic for unit evaluation and optimization the BUG 8 console debugger TED 8 text editor HASL 8 assembly language and extended Benton Harbor Basic An extra diskette is also included Prices H17 Floppy Kit 530 H17 1 optional second drive 295 H8 17 operating system software 100 Circle number 1 on Reader Service Coupon Dual Floppy Z 80 Based Microcom puter Vector Graphic s Vector 2 is a general purpose byte oriented digital computer based on the 2 80 microprocessor and industry standard S 100 bus This new high performance low cost 3750 unit also features two Micropolis Quad density floppy disks which makes it suitable for hobby and small business markets according to the company Notable features include the 2 80 CPU with 158 basic machine language instructions and a minimum instruc tion cycle of two microseconds An 18 slot motherboard provides flexibility and expansion capabilities for up to 64K of directly accessible memory using a parallel 8 bit word 16 bit address Up to 256 separate input and output devices can be addressed Two disk drives are mounted directly to the front panel to provide instant acce
216. primary what voltage will appear at the secondary 24 Ifthe load impedance of the secondary circuit is 1 ohm how much current will flow in the primary 25 What is the impedance of the primary ANSWERS 22 10 000 SS 1 000 10 to 1 turns ratio 23 N _ 10 _ 100 n p Wir TES 10 Me 24 Current in the secondary is 10 amperes 10 1 1 ampere 25 The impedance of the primary circuit is E i 100 ohms 1 MAGNETIC AMPLIFIERS Magneitc amplifiers are special transformer like de vices that use a small amount of power to control larger amounts of power thus acting as amplifiers They are simple rugged and efficient as compared to 82 other forms of amplification Magnetic amplifiers take advantage of a special property of iron or steel in a strong magnetic field To explain how a simple magnetic amplifier works let s first review the basic principles of a coil When a current flows in a coil a magnetic field flux is set up inside and around the coil If the current is AC the field also alternates But in any case the strength of the magnetic field the number of lines of flux produced depends on the material inside the coil as well as how much current is flowing through the coil A very simple type of magnetic amplifier is based on the fact that an iron core normally allows greater changes in the magnetic field and therefore increases the inductive reactance of a coil
217. pron has sockets for the AC linecord a DC power cord the antenna jack a remote speaker and a line level output for a recorder Screw type binding terminals are used for the aux control A gimbal bracket such as supplied with mobile CB transceivers is pro vided for mounting the Bearcat 250 in a vehicle Plugs in the side of the cabinet normally conceal the threaded eyelets for the mobile bracket s screws Summing Up The Bearcat 250 priced at 399 95 complete with AC and DC power cords mobile bracket and telescopic antenna is one heck of a scanner Overall performance is just about typical for high performance scanners such as previous Bearcats The thing that makes the 250 stand head and shoulders above other scanners is the on board computer Fact is it does so much that it takes a thorough read thru of the manual before you can even start to get maximum utilization of the special computer features Best bet is to stop into a local Bearcaf dealer and get a hands on demonstration Make certain you get a salesperson who really knows the 250 inside and out or you re likely to miss one or more of the out standing features in a store demo For more information on the Bear cat 250 circle No 79 on the reader s service Coupon BEAHLHM 1 Thirty pushbutton keys control all functions and the frequency selection The five keys in the left vertical row select channels in groups of 10 1 10 11 10 21 30
218. pt all DIP sizes Everything is quality all the way You can even see the difference in our harder shinier plastic matrix See for yourself Phone toll free 800 321 9668 for the address of your nearby A P Products dealer And ask for our complete A P catalog The Faster and Easier Book AP PRODUCTS INCORPORATED Box 110Ce 72 Corwin Drive Painesville 44077 Tel 216 354 2101 TWX B10 425 2250 Faster and Easier is what were all about CIRCLE 29 ON READER SERVICE COUPON MEETO ipi gt gt 17 ow NRI makes it TVAudio home gt Side by side to be a problem Catalogs are radically equipment comparison different and some are not too clear as to of NRI and two what you actually get for your money So other leading schools NRI has done a lot of the work for you shows what you get And put the prices right up front so you for what you pay can make your own judgment When you have to pay Of course we can t compare every as much as 985 more for another school s course thing Lesson clarity and content vary What one covers here another covers you should carefully there or not at all The material one consider your tuition school breaks down into eight lessons investment may be four at another And the qualifi When you sit down and try to pick cations and abilities of instructors are out the school that s best for you it gets another question saxa SCHOOL COURS
219. puters never cheat pro grammers sometimes do but never com puters The 1 was added so that the 996088 070 1 0 Computer Game Microcomputer Edition From Creative Computing Publishers this book features clear typography and com plete sample runs Circle no 93 for info secret number will never be a zero OK compute Let s see now RND 0 well this time around let s pick 33456709 at random Multiplying that by 100 we get 33 456709 Chop ping off to the right of the decimal point leaves 33 and adding one makes 34 Ah Ha Our secret number X is equal to 34 At line 330 you leer computerishly and tell your human partner that you now have a number for him to guess You ignore REM line 400 PRINT a line space as per line 410 then go onto line 420 which tells you to PRINT out a question to your human You do so then see the line ends in a semicolon The semicolon tells you to put what ever comes next on the same line Next is line 430 an INPUT statement What ever number the human types here will become variable G The INPUT state ment causes you to output a prompting question mark and the question mark is placed on the same line as the PRINTed question Fast as you could reasonably expect 54 WHAT TO DO AFTER YOU HIT RETURN lt First Book of to making computers fun and this book is somewhat a classic Circle number 84 of a hunk of animated pro
220. r 477 um m me d GEO AS Gee Ha m 9j CIRCLE 22 ON READER SERVICE COUPON 214 681 047 Ld E A 3 THE GREAT ELECTRONIC THINGS amp SURPLUS CATALOG Many Unusual Items amp Specials not found in stores or catalogs anywhere Circle Reader Service Coupon or write to day for exciting Free Catalogi MAGIC SOUND SWITCH SURPLUS BARGAIN Sensitive crystal mike picks up sound which Is amplified to trigger an SCR switch Opera tes on 3 6 V OC With schematic 2 oz 024510210 10 8 95 100 79 95 112 VOLT 2 AMP POWER SUPPLY 10 89 95 Sensational purchase of Euro pean Inventory 3 4 amp surge Excellent for CB car stereo and general hobby and school shop applications Excellent battery charger Excellent dealer Item 024HP233 2 16 1 BUILD A PARABOLIC MICROPHONE Glant 22 diameter ptastic parabolic sound reflector For construction of long distance mikes and sound projectors Construction ideas included 5 10 024MP233 amt Rush your order with full remittance please Visa amp Mastercharge OK Allow 15 for UPS amp handling N Y state residents add 796 E 24 hour 7 day telephone order desk when rates are low ELECTRONICS NORTH COUNTRY SHOPPING CENTER PLATTSBURGH N Y 12901 518 561 8700 CIRCLE 11 ON READER SERVICE COUPON 9 DEVICES ut PHASERS PPF 1 PHASER PAIN FIELD Thi
221. r RF Mixer 3 to 20 MHz Cat No 035105 20 to 170 MHz Cat No 035106 5 50 ea SAX 1 Transistor RF Amp 3 to 20 MHz Cat No 035102 20 to 170 MHz Cat No 035103 5 50 ea BAX 1 Broadband Amp 20 H2 to 150 MHz Cat No 035107 5 75 ea International Crystal Mfg Co 10 North Lee Oklanoma City Oklahoma 26 02 Calibration Tolerance EXPERIMENTER CRYSTALS HC 6 U Holder ea Specifications 3 to 20 MHz For use in OF 1L OSC Specity when ordering 20 to 60 MHz For use in OF 4H OSC Specity when ordering WRITE FOR BROCHURE gem CIRCLE 24 ON READER SERVICE COUPON Got a question or a problem with a project ask Hank Please remember that Hank s column is limited to answering specific electronic project questions that you send to him Personal replies cannot be made Sorry he isn t offering a circuit design service Write to Hank Scott Workshop Editor ELEMENTARY ELECTRONICS 380 Lexington Avenue New York NY 10017 enjoyed it Couple of Clubs Please tell me the address of any Ameri can radio club that specializes in the re ception of AM broadcast stations Thanks E H Delray Beach FL National Radio Club Membership Cen ter P D Box 118 Poquonock CT 06064 and International Radio Club of America IRCA P O Box 26254 San Francisco CA 94126 both specialize in medium wave AM broadcast DX exclusively How Old is 20 Whats all this baloney about CB being born 20 years ago W
222. r ceil dimensions Size in Amp 365X1 91 60 4 oz 865X1 63 120 5 oz PIEZO ELECTRIC Operates 3 88 Great 3 SUPER HORN Just add case amp speakers 8520307 24 88 eaor Sh Wt 4 Lbs 8H30331 SPECIAL 8 AA cells in handy package gives 10V Split into single cells for 1 25V _8v20305 8 00pack CHARGEABLE 1 25V Used good condition Sizes are AA oversize amp sub C check Hr Sh Wt Order No 7V70468 7V 70470 MOTOROLA S TWEETERS ouper Horns amp Direct Radiators No crossovers required High Impedance High Output Excellent Transient Res ponce Low Harmonic Distortion Tom orrow s tweeters today from B amp F Sh Wt 2 Lbs 8 30248 14 88 Pr t 2 5 Piezo Ee ic Horn Ten Sh Wt 3 Lbs 8H30332 17 88 Pr t2X6 Piezoeleetric Horn Tweeter 23 98 Pr FREE JUMBO CATALOGI JAM PACKED WITH SURPLUS ELECTRONIC PARTS GADGETS KITS AND MORE CIRCLE READER SERVICE COUPON T ELEMENTARY ELECTRONICS January February 1979 CIRCLE 6 ON READER SERVICE COUPON Size 24 x 68 with rails on front amp back for moun ting equipment on 19 ters No doors or sides List Price 185 00 NEW SUR PLUS Your cost only 50 each Qty Itd Frt Collect 8082049 50 00 ch EELEL SA AL SE TS T AKR tt TV
223. r is reversed many times each second these tiny expendi tures of power add up to a noticeable loss Hysteresis loss can be reduced by constructing the core with a type of iron that is very easily magnetized and de magnetized QUESTIONS 17 If a transformer supplies 1 9 amperes at 100 volts to a resistive load in the secondary circuit and if it dissipates 200 watts of power in the primary circuit what is the efficiency of the transformer 18 This transformer has a relatively high low etti ELEMENTARY ELECTRON ICS January February 1979 ciency 19 If the secondary of a transformer supplies 0 99 watt at 1 000 volts and the transformer has an efficiency of 99 what power will the primary draw at 120 volts 20 How could you find the amount of power lost due to resistance in a transformer 21 Does an air core transformer have hysteresis or eddy currents ANSWERS 17 The power dissipated in the secondary will be 1 9 x 100 190 watts The efficiency of the transformer will be 190 200 95 18 It has a relatively low efficiency An efficiency below approximately 9796 is considered to be low A19 The voltages have no effect on the problem The efficiency of the transformer is equal to output power divided by input power The input power must be 1 watt 20 You would have to measure the resistance of both windings and then calculate the power dissipated due to the current in the windings 21 An air core transform
224. ral message center It would accept incoming com munications and store them on the disk under a name or special code of the intended recipient At some later time a person using the network could dial the central computer to see if any mes sages were stored under his name or code For additional privacy messages could be encoded by the sender s com puter before being sent and could then only be decoded by the intended re ceiver who would run them through a decoding program after requesting them from the central disk storage Data transfer rates on personal com puter networks are currently 110 or 300 baud but baud rates of 1200 are fea sible The message can therefore be written checked and edited on the sender s home computer terminal while the computer is off line When the mes sage is ready the sender simply goes to his transmit program enters the tele phone number and file name and the computer will automatically dial up the central system and when it is acknowl edged transmit the message at a rate faster than any human could type The savings on telephone bills should be substantial Neither rain nor Snow The use of a central system as an electronic post of fice does not preclude direct access between individual personal computers Exchanges of software and personal communications would make possible fast distribution of newly written pro grams and participation by many peo 52 ple in ong
225. re a snap with these shunting techniques 43 Mini Reg now your power supply worries are over for good COMPUTER CAPERS 51 Computer Readout watch computers gossip with each other 53 Basically Fun how to match wits with a microprocessor 56 Computer New Products some of the newest in computer equipment and accessories 70 Simply Basic this BASIC program lets you make odds on your favorite sports team THEORY FOR TODAY S HOBBYIST xr 61 Digital Counting you can learn to count like a computer 67 Stop Static build the cleanest circuits on the block 79 Basic Course bone up on all the transformer theory you ve forgotten SHORTWAVE SUBJECTS 22 DX Central Don Jensen guides you around Columbian shortwave broadcasting vy 34 Come The Sunspots you won t recognize shortwave for the next few years and e e tells why CB SPECIFICS 71 Kathi s CB Carousel Kathi looks at some interesting new circuitry from Lafayette yy 77 CB Transceiver Checkout four of the hottest new sets get the going over e e CHECKS OUT 50 Indy Cator Auto Tach find out how fast your engine s racing vy 60 Information Unlimited Mutt Minder their bark isn t always worse than their bite amp 75 Bearcat 250 Programmable Scanner what more can technology do 78 Emergency Multicore Solder throw away that extension cord ANTIQUE RADIO REVISITED 41 Antique Restoration tix up those old receivers and pack away your troubles 73 Antique Radio Corner
226. re in less time For less money NEED MORE INFORMATION CALL 203 624 3103 to order or for the name of your local distributor Prices slightly higher outside U S A Manufacturer s suggested retail CONTINENTAL SPECIALTIES CORPORATION Corporate Headquarters Continental Specialties Corporation 70 Fulton Terr Box 1942 New Haven CT 06509 351 California St San Francisco CA 94104 415 421 8872 TWX 910 372 7992 Europe Africa Mid East CSC UK LTD Shire Hill Industrial Estate Units 1 and 2 Saffron Walden Essex CB 11 3AQ Telephone Number SAFFRON WALDEN 21682 TLX 817477 CIRCLE 9 ON READER SERVICE COUPON The Realistic CT 50 tells it like it is Why double Dolby 3 Heads Two independent record and play heads eliminate the compromises of one combined r p head and the head assembly is integrated to eliminate azimuth error The result cleaner sound The third head lets you monitor your recording an instant after its made without in terrupting the program SCT 30 bar 3 heads 2 Capstans Dual capstans instead of the usual 1 reduce wow and flutter to an inaudible 0 06 WRMS or less and extend the audio fre quency response SCT 30 has dual capstans Double Dolby You know the single Dolby system cuts noise and adds dynamic range But let s examine double Doiby You get Dolby on botb record and monitor so you know exactly what your tape will sound l
227. res a 13 5 dB gain over an isotropic source and front to back and side separation of CIRCLE 66 ON READER SERVICE COUPON 30 dB SWR at resonance is 1 1 1 Im pedance match is 50 ohms Signal Track er is gold EPC coated for maximum weather protection VSWR can be ad justed to obtain optimum performance 3455 Conner St on a desired channel The antenna works with 23 and 40 channel transceivers both AM and SSB Model 5059 price 79 95 For more information write to Channel Master Ellenville NY 12428 Calculator Size Counter CSC has introduced their new Mini Max Counter a small inexpensive counter with 50 MHz performance The Mini Max features a six digit magnified LED dis play with 100 Hz resolution Decimal points after the second and fifth digits act as pilot lights and indicate MHz and KHz points on the display The counter CIRCLE 62 ON READER SERVICE COUPON display updates ten times per second permitting easy speed read mode fre quency tuning without the usual one second delay between counter readings 9 y OK MACHINE amp TOOL CORPORATION 212 994 6600 Telex 125091 Bronx 10475 A UHF FET preamplifier provides weak signal performance permitting the Mini Max to be driven directly from an op tional accessory whip antenna Using a standard TV color burst crystal for its timebase the Mini Max achieves 3 ppm timebase accuracy user trimmable s
228. rm of lower tuitions more Mi equipment carefully designed courses and effective lessons Send for Free Catalog EN No Salesman Will Call ro d Send for our free catalog today and get all the details See every piece of equipment and kit you get a complete listing of fully described lessons expla nations of each and every experiment you perform Read about NRI s background 4 a and qualifications career opportunities ate What NRI graduates say about their training costs and monthly payment plans for the courses that interest you ay Then compare NRI value and results and make your decision Like the million C Hw that have gone before you we think Build and keep 2 meter transceiver test equipment you ll choose NRI Send the card today for a communications career OrcheckoutNRI value training in Computer or Communications CB Equipment Servicing If you re interested in learning how TV broadcasting and much more NRI to service and maintain digital computers can help you there too as you build check out our NRI course You learn at and experiment with your own digitally home in your spare time and actually synthesized 2 meter transceiver For these build a programmable and other NRI home study courses just integrated circuit dig check the postage paid card and mail ital computer with today If card is missing write to expanded memory E
229. rs What ever your particular involvement with rhythm you will find the R amp B Box a valuable companion A metronome is the traditional aid for timing in music but it falls short in the rhythm department because the clicks it produces are all identical In music rhythm comes about when each beat does not receive identical empha sis With the R amp B Box you can over come metronomic monotony by giving each click in a sequence a different emphasis to produce musical rhythms A notable feature of this rhythm synthesizer is that it is not limited to standard or preset rhythms but can be set up to generate thousands of rhythms of all kinds Furthermore each rhythm is precise to the micro second Let s find out how the Rhythm and Blues Box accomplishes its feat by taking a tour of the circuit Even at second glance the circuit may seem formidable but it can be understood by tackling it a section at a time Each IS THE TIME PATTERN of section is a basic building block which you may meet in other circuits also the multivibrator shift register flip flop latch analog switch and multi plexer Good Vibes We ll begin our tour with IC2 a 555 timer and its asso ciated components These form an as table free running multivibrator that generates a continuous train of pulses Just by properly set ting the controls you can program our Rhythm and Blues box for any kind o beat you might want to tap your toes t
230. rs are quickly discovering that the number of time saving applications exceed their original expectations For example you can measure unmarked capacitors Verify capacitor tolerance Measure cable capacitance Select and match capaci tors for critical circuit applications Sample production components for quality assurance Measure capacitance of complex series parallel capacitor networks Set trimmer capacitors to specific amounts of capacity Check capaci tance in switches and other components DYNASCAN CORPORATION by d a 6460 W Cortland Street Chicago IL 60635 312 889 9087 In Canada Attas Eiectronics Ontario International Sales Empire Exporters inc 270 Newtown Road Plainview L I N Y 11803 CIRCLE 23 ON READER SERVICE COUPON mni ecvronics 4th sigq 29 36 AES eem F sounds that enables us to dis tinguish a march from a mazurka and it is one of music s basic ingredi ents It could also earn a stack of votes from both beginner and veteran musi cian alike as one of the most trouble some But help can be close at hand if you build the rhythm synthesizer described here Use our Rhythm and Blues Box while practicing on an instrument to ana lyze or demonstrate rhythms even for learning dances It can also be con nected to a percussion generator to provide simple accompaniments or can serve as a programmable con troller for music synthesize
231. ry 9 Yes 10 The stronger the magnetic field the greater will be 80 the impedance of the primary circuit 11 More current would flow in the primary TRANSFORMER POWER If the transformer was 10096 efficient all the power from the primary winding would be transferred to the secondary and delivered to the load Suppose a transformer has 1 000 turns in the primary and 6 500 turns in the secondary If 100 volts is applied to the primary 650 volts will appear at the secondary Now suppose the load connected to the secondary is 65 ohm resistor It will draw a current of 650 65 10 amperes and the power consumed will be 650 x 10 or 6 500 watts This power must be supplied by the primary winding Assuming no loss in the transformer the primary winding must supply 6 500 watts The pri mary current therefore will be 6 500 watts 65 amperes 100 in exactly the same proportion as the voltage was step ped up The power transferred from the primary to the secondary does not change however regardless of the turns ratio This is true providing the rating of the transformer has not been exceeded and assuming 100 efficiency QUESTIONS 12 What happens to current in the secondary of a transformer when a load is connected across its terminals 13 Will a magnetic field be produced by the current in the secondary 14 Will the magnetic field add to or oppose the mag netic field produced by the primary Remember
232. s This mode of operation of the shift register where the bits play follow the leader is called the serial mode Some shift registers like the one in the Rhythm Synthesizer can also operate in the parallel mode In this mode the inputs of the flip flops are disconnected from the outputs so that all the flip flops can be loaded simultaneously from outside during a single clock pulse In the R amp B Box IC s 5 6 and 7 each a four bit shift register are cas caded to form a 12 bit shift register 29 a 2 RHYTHM amp BLUES As described later to start a rhythmic pattern the shift register is loaded in the parallel mode with a high in stage L and ows in the remaining 11 stages The shift register is then put into the serial mode and clocked by the posi tive clock pulses from pin 4of IC3D which shift the single high from stage to stage left to right in the circuit diagram Thus the otuput of each stage goes high in sequence This con tinues until the Aigh reaches the stage selected by the Sequence Length switch S3 S3 then feeds the high to the input of a D type flip flop pin 9 of IC4 A D type flip flop has the character istic that the logic level high or low present at its input before it is clocked will be assumed by its output after it is clocked However note that the clock input pin 11 of IC4 of the D flip flop is fed the inverted clock pulse from pin 3 of IC3C So when the shift register is being clo
233. s P O Box 9884 Atlanta GA 30319 and another from International Data Sys tems 400 North Washington Street Suite 200 Falls Church VA 22046 Both these devices have the capability of dialing and answering the telephone automatically under software control an important consideration for using the computer with a network Most telephone company tariffs re quire that there be an adaptor on the phone line This can of course be rented from the telephone company The adapter may or may not be useful electronically but it does insure that the user is treated as a data customer by the telephone company This means that the loop between your house and the central office must conform to the spe ELEMENTARY ELECTRONICS January February 1979 cifications for data transmission and there is less likelihood of losing data due to poor communications lines Computers operating on the same network must all use an agreed upon protocol or format for their data That is it must be transmitted at a standard baud rate and in a configuration with such things as headers data blocks and checksums as a standard These formats should also be compatible with or trans lateable to the formats used by mass storage devices such as floppy disks One common form of protocol is to transmit data in packets which consist of a header telling various things about the data such as its type source desti nation length etc and then a block cont
234. s after which may cancel my membership at any time 101 300 578 800 811 841 856 874 919 929 966 1011 1015 1019 1023 1028 1054 1055 1060 1064 1070 1088 Name Phone Address O OENE State Zip Valid for new Members only Foreign and Canada add 10 EE 19 Large size 812 x 1012 If you missed our sold out first issue we re real sorry Here now is the Spring 79 issue 112 pages with lots of illustrations full of SF excite ment adventure and fun The cover pic is reproduced in a full color 10 x 16 poster It comes with every copy Chock full of stories this issue brings you for example Starschool the first col laboration by the noted SF writers and brothers Joe and Jack Haldeman And Keeper smith a novelette by Randall Garrett and Vicki Ann Heydron And a short story by Isaac Asimov himself How It Happened ASIMOV S SF ADVENTURE MAGAZINE 380 Lexington Avenue New York NY 10017 Enclosed is 1 75 plus 25 handling shipping total of 2 00 for the Spring 1979 issue 2 of ASIMOV S SF ADVEN TURE MAGAZINE EEJ F 79 please print Address City State 84 Basically Fun Continued from page 55 gestions while others contain just list ings What To Do After You Hit Return published by People s Computer Com pany P O
235. s founded by a retired doctor E T Drake and his wife The museum con tains over 300 phonographs on display with about 300 more in storage Those in storage are either used for parts or are rotated periodically with those on display to make a repeat visit worth while The museum contains a com plete display of the phonograph from its start to about 1930 Also on display are some ate 1930 s radio phono com binations and six Jukeboxes The own ers conduct guided tours and the com mentary is outstanding in its complete ness The museum is open to the pub lic on Saturday Sunday and Holidays from May 1 to November 1 Hours are This view from inside the Midwest Phonograph Museum shows a forerunner of the Juke box on the near right At the far left is a Wurlitzer jukebox with a Bandbox just above from 2 00 PM until 6 00 PM and an admission is charged During the tour of the museum you will learn about Thomas Edison Emile Berliner and Eldridge Johnson all early pioneers of the phonograph in dustry There is a large painting of the dog Nipper listening for His Masters Voice If you are in central Indiana while on vacation or business I would recommend that you take time to visit the museum Visitors are encouraged to bring cameras and take as many photographs as they like Meters We will continue our dis cussion On voltmeters in this column In one of the photos you will see a wooden cigar box that is a
236. s device recently devel oped and patented in our labs s being evalualed by law enforce ment agencies for riot and crowd control 11 15 now avaiable but soon will come under the jurisdiction of weapons and infernal machine control making it unavailable to the public The device is hand held and looks like a BUCK ROGERS gun tt rs hazar dous if nof used with discretion PPF 1 PLANS 10 00 IPG 1 INVISIBLE PAIN FIELD GENERATOR This amazing simple hand held device is aboul the size of a pack of cigarettes and generates a directional field of moderate 10 inten sive pain in the lower part of the head up to a range of 50 De vice 15 simple and economical to make IPG 1 PLANS 6 00 IPG 1K ALL PARTS 39 50 IPG 10 ASSEMBLED amp TESTED FOR ANIMAL CONTROL 44 50 LASERS JK HIGH POWERED CARBON DIOXIOE BURNING AND CUTTING Compiete plans and all parts sources 10 00 SOLID STATE IR t2 WATTS with buit n power supply plans 6 00 Complete kit with collimator 44 50 POCKET LASER pulsed visibie red plans 6 00 Complete kit 39 50 Also complete plans and parts sources for RUBY YAG NEODYNIUM HeNe ARGON DYE NITROGEN and many more lasers Tp SECURITY ag SNP 2 SNOOPER PHONE Connects to lele phone in sec onds enabies you to check home or office while on vacation User simply dials his number trom anywhere activating highly sensitive mike and amp combination capable of detecting normal sound levels throughout area wit
237. s of the future systems and more from in home study 1293 3JISP 0 and every piece of equipment included Send for it today and see for yourself whats really happening in electronics training technology at NTS Find out how much has changed and what new directions the field is taking You ll probably want to be a part of it It s free Just mail the card or coupon Today NO OBLIGATION NO SALESMAN WILL CALL APPROVED FOR VETERAN TRAINING NATIONAL Ge SCHOOLS r gt TECHNICAL TRADE TRAINING SINCE 1905 Resident and Home Study Schools 4000 South Figueroa St Los Angeles Calif 90037 re N AL 20109 jeubig pem E m bI S PHI E ATIONAL TECHNICAL SCHOOLS Dept 222 019 4000 South Figueroa Street Los Angeles California 90037 Please send FREE Color Catalog and Sample Lesson Color TV Servicing 1 amp W TV and Radio Servicing O FCC License Course Electronic Communications Electronics Technology O Audio Electronics Servicing O Digital Electronics C MicroComputers MicroProcessors Name E Address lt ame Apartment Number l1 City N db State s Se ME C L Check if interested in G I Bill information Check if interested ONLY in classroom training in Los Angeles Keep up with current events by expanding your meter s amp ability by Jeff Jones ITH THE RIS
238. s of the publisher are located at 380 Lexington Ave New York NY 10017 Names and addresses of publisher editor and managing editor Publisher Joel Davis 380 Lexington Ave New York NY 10017 Editor Julian S Martin 380 Lexington Ave New York NY 10017 Managing di tor Alan H Rose 380 Lexington Ave New York NY 10017 Owner is Davis Publications Inc 380 Lexington Ave New York NY 10017 the names and addresses of stockholders owning or holding 1 per cent or more of total amount of stock are Davis Publications Inc 380 Lexington Ave New York NY 10017 Joel Davis 3BO Lexington Ave New York NY 10017 B G Davis Trust 380 Lexington Ave New York NY 10017 Carol Dovis Teten 380 Lexington Ave New York NY 10017 Known bondholders mortgagees and other security holders owning or holding 1 per cent or more of total amount of bonds mortgages or other securities None The average number of copies of each issue during the preceding 12 months are A Total number of copies printed 280 254 B Paid circulation 1 Sales through dealers and carriers street vendors and counter sales 39 938 2 Mail subscriptions 171 051 C Total paid circulation 210 989 D Free distri bution by mail carrier or other means samples complimentary and other free copies 863 E Total distribution sum of C ond D 211 852 Copies not distributed 1 Office use left ov r unaccounted spoiled after printing
239. s that never get in the RST quantity Send tor om atia is ELECTRONICS RMS of continuous power Suggested re ATLANTA GEORGIA electron the 2 MEET IS tail price is 19 40 For further informa DELTA ELECTRONIC HOBBIES EBELEN AMESBURY 55 tion contact Acoustic Fiber Sound Sys 5151 BUFORD HWY DORAVILLE ATLANTA GA AREA 388 4705 01913 tems Inc P O Box 50829 Indianapolis IN 46250 ti 94 GIRCIHE UIS ERN REE PE CE GM PON ELEMENTARY ELECTRONICS January February 1979 zen LITERATURE LIBRARY 301 Get into the swing of microcomputer and microprocessor technology with CREl s new Pro gram 680 New 56 page catalog describes all pro grams of electronics advancement A302 Big catalogs are coming back Burstein Apple bee will send you theirs It s a parts bonanza every experimenter would want to see Latest is over 200 pages 303 Graymark s catalog reveals a host of products and kits every experimenter would like to have Unusual binary clock is a winner A must catalog for the beginner 304 Dynascan s new B amp K catalog features test equipment for industrial labs schools amp nd TV servicing 305 A new 4 page directional beam CB antenna brochure is available from Shakespeare Gives complete specs and polarization radiation patterns for their new fiberglass directional antennas 306 Antenna Specialists has a new 32 page CB and monitor an
240. sage lt 15 W e Battery or line operation e2 9 Hx64 W x 8 0 D Non Linear Systems Inc Originator of the digital voltmeter Box N Del Mar California 92014 Telephone 714 755 1134 TWX 910 322 1132 CIRCLE 38 ON READER SERVICE COUPON 12 HEY LOOK ME OVER Continued from page 4 tact Continental Specialties Corporation 70 Fulton Terrace New Haven CT 06509 Checkbook Calculator The all new National Semiconductor Data Checker a new thinline checkbook cal culator with three continuous memories allows a user to maintain and update both checkbook balance and balances for any two selected charge accounts The three memories are simple to use and do not interfere with usage of the cal culator The Data Checker designated NS 103 was engineered for consumer ease of use Balances are maintained even when the unit s power is off and automatically updated as each new transaction is made Balance figures as well as calculator read outs are dis CIRCLE 44 ON READER SERVICE COUPON played on large Liquid Crystal Display LCD with 6mm digits The Data Check er is also a full function calculator in cluding a percent key with auto matic add on discount and net Sug gested retail price for the Data Checker is 39 95 with checkbook case and pen included The unit is now available from National Semiconductor s Consumer Products Division 1120 Kifer Road Sunnyvale CA 94086 Blood
241. scilloscope screens are simulated Check box for G I Bill information Mail today Veteran Cleveland Institute of Electronics Inc 1776 East 17th Street Cleveland Ohio 44114 Accredited Member National Home Study Council YES John I want to learn from the specialists in electronics CIE Send me my FREE CIE school catalog including details about troubleshooting courses plus my FREE package of home study information EL 06 Print Name MEM EN Address M EN Apt REM E E a State Zip Auc Phone area code Active Duty NL HOBBY WORLD CATALOGUE The new Hobby World Catalogue 20 pages of factory prime professional quality equipment no surplus Comput ers add on boards prototype boards IC s sockets resistors supplies tools test equipment books and more Shop your buy list You ll find what you want in Hobby World and at a solid savings SPECIAL 16K MEMORY ADD ON FOR APPLE OR TRS 80 ONLY 98 00 TERRIFIC PRICE specify when ng To order or request free Catalogue write Hobby World 19355 Business Center Drive 6 Northridge California 91324 TELEPHONE ORDERS Inside Calif 213 886 9200 Outside Calif 800 423 5387 CIRCLE 35 ON READER SERVICE COUPON BY POPULAR DEMAND MS 215 Dual Trace Miniscop With Rechargeable Batteries amp Charger Unit 435 e 15 megahertz bandwidth e External amp internal trigger e Auto or line sync modes e Power u
242. sly updated data base Until now the largest data bases open to the public have been news papers and television These required a person to sit and search the media him casting you can let your digits do the searching and seek out a new item want ad or service or a collection of items having some subject in common which is of interest to you and which you can define yourself One example might be to tell the computer to save all news items con taining the words Brazil and coffee Thus one would have a file of the politi cal and other events taking place in Brazil as well as a report on the coffee market and prices Similar applications come to mind with real estate listings Specify the size and price of the house you are looking for as well as the area classify ads prior to broadcasting Each individual s computer will take care of that Even magazine subscriptions could be sold this way by simply giving sub scribers the monthly code keyword It is estimated that no more subscriptions would be lost by having keywords passed around than are now lost by people passing around actual copies of magazines Let me point out that two years ago the topics in this article would have been classified as blue skying or real izeable fantasy Today they exist Several Personal Computer Networks are operating and more are getting started The Digicast Project hopes to have at least one broadcast facility in opera
243. specialists When you send us a completed lesson you can be sure it will be reviewed and graded by a trained electronics instructor backed by a team of technical specialists If you nced specialized help you get it fast in writing from the faculty spc cialists best qualified to handle your question People who have known us a long time think of us as the FCC License School We don t mind We have a fine record of preparing people to take and pass the government administered FCC License exams In fact in continuing surveys ncarly 4 out of 5 of our graduates who takc the exams gct their Licenses You may already know that an FCC License is needed for some careers in clectronics and it can be a valuable credential anytime Find out more Mail this eard for your FREE CATALOG today Ifthe card is gone cut out and mail the coupon Pll send you a copy of CIE s FREE school catalog along witha complete package of independent home study information For your convenience trv to arrange for a CIE representative to contact you to answer any questions you may have Remember if vou are serious about learning electronics or building upon your present skills your best bet is to go with the clec tronics specialists CIE Mail the card or coupon today or write CIE and mention the name and date of this magazine 1776 East 17th Street Cleveland Ohio 44114 Patterns shown on TV and o
244. ss and ease of operation These advanced 5l4 inch floppy disk drives offer the much larger capacity and greater reliability previously available only in 8 inch disk drives Storage capacity of each drive is 315K bytes formatted Also includes 32K of static RAM 12K 2708 PROM RAM board with extended monitor and Vectors powerful Basic Comes assembled and tested ready for connection to an intelligent terminal and printer A single disk version is available for under 3 000 Circle number 71 on Reader Service Coupon VECA ME 56 Apple 2 Serial 1 0 Board Electronic Sys tems offers a serial 1 board for the Apple 2 computer Software includes in put and output of basic programs and monitor to a teletype or other serial de vice and a program for using the Appie 2 for a video terminal Input and output are RS 232 The board has switch selectable parity number of stop bits and jumper selectable address Data rate to 30 000 baud Full documentation included The serial O is available as an assembled and tested unit for 62 as a kit with parts for 42 or as a circuit board only for 15 Circle 72 on Reader Service Coupon Calculator Programming Aids Special ized computer programming aids offered by Texas Instruments are designed for use with the company s TI Programmable 59 handheld calculator The programs provide easier conversion of ASCII and EBCDIC codes routines for debugging and analyzin
245. ss conie E Radio SHACK user E 15 14 Scientific Systems 90 25 B 7 26 Southwest Technical 2 ELEMENTARY ELECTRONICS January February 1979 THH lest Faster easier and more economical digi tal testing That s what CSC s Logic Probes are all about And that s what engineers technicians and hobbyists need to deal with the increased use and complexity of digital circuits Unlike oscilloscopes meters and other conventional test equipment CSC probes are ogic state oriented Just touch the probe to a circuit node and instantly read logic state detect level transitions check duty cycles And store high speed low rep rate events that even fast scopes miss By accurately detecting the state of indi vidual logic elements without removing ICs or cutting copper paths CSC s circuit powered multi family Logic Probes locate over 95 of circuit problems in minutes instead of hours And they re easy to use Simply connect two Clip leads across the power supply touch the probe p to a node and watch the LEDs LP 1 LOGIC PROBE 44 95 LP 1 has aminimum detectable pulse width of 50 nanoseconds and maximum input frequency of 10 MHz This 100 K ohm probe is an inexpensive workhorse for any shop lab or field service tool kit It detects high speed pulse trains or one shot events and stores
246. t SG 2 for 1 01 15 POP OPTICAL LENSES piano convaz 1 dia plastic 30 for 1 20 J 10 1C DICE microscopic circuits teaches theery L lt 5065 20 for 1 20 1 6 SPEAKER tull ronga cer n home Le 52 4 2 for 4 96 C L LED WATCH GUTS men s how good Wa den t know 2 for 1 96 O i UHF TUNER solid stata standard ty 292 Lang ERa h deett nts 2 for 1 01 D 10 SLIDE SWITCHES sest pop styise i orci rte vens c mom ate a 20 for 1 01 4 TANTALUM CAPACITORS 6 9 uf 35V dipped LT TL erry 8 tor 1 01 5 PHOTOCELLS 600 to 15K ohme 2939 eco ditta 10 for 1 01 1 100KHZ MARKER CRYSTALS approx for merkar gan 2 tor 1 96 i MOTHERBOARD EDGE CONNECTOR 106 pins 125 2 for 3 51 1 48 EDGE CONNECTOR 1248 spacing 398315 dices n an he 2 tor 1 94 O 1 S PST 24V REEO RELAY norm dip style 1250 ohm te 75179 5 hits a 1 49 2 fer 1 50 150 PREFORMED DISC CAPACITORS marh d ssst d 2608 OQ 2 00 300 for 2 01 10 CALCULATOR KEYBOARDS 20 keys ond up 9 3 24 eR 25 EEE PETITE SES 2 00 20 2 01 3 ALARM WARNING STICKERS lor windows 2 3 4 3 8338 1100 ter 1 01 10 CALCULATOR SWITCHES P T N O asst d 4 S371 1 00 20 for 1 01 1 ITT 6 OIGIT COUNTER 11 OVAC with mounting fien ls HON ar nK 1 95 2 for 1 96
247. t To simplify construction of the dem onstration circuit accompanying this ar ticle a Continental Specialties Corpora tion PB 203 solderless breadboard was used It allowed almost infinite experi mentation with various circuit arrange ments experimentation that would have otherwise consumed a prohibitive amount of time All parts mentioned in the parts list and article are easily obtainable through mail order houses see the HoBBv Mart in the back of this issue or from most electronics parts distributors The parts in the ar ticle are referred to by their common name since many parts with different numbers can perform the same tasks The parts used in the demonstration circuit are identified by their generic ELEMENTARY ELECTRONICS January February 1979 part number most parts distributors will have a cross reference from this number to the manufacturer s part number Translating As you can see in the diagram of the seven segment display any digit from zero to nine can be represented by a certain combination of lit LED segments Each of these segments is an individual LED with its cathode tied to a common ground hence the name common cathode some have common anodes Each segment can now be activated by a switch between the anode and a power source Switching on segments a c d f and g for example will cause the digit five to be lit As a practical consideration be sure to use a current limiting resistor 110
248. t in a darkened or semi darkened room the Motion ZT ar movement for a minimum distance of 8 ft The secret in the Detector acts as a fantastic FIRE ALARM The light from a ultra complex custom LSI chip which combines the latest in aingle match anywhere in the room triggers the alarm thal linear amp digital circuitry e device is completely self the device becomes an intrusion alarm and fire alarm all in one e 5 contained in a case 6 x 24 and operates from four AA Deita No Description Sale NiCad batteries Nothing elae ia needed forthe device to perform 0 56115 Complete es detector kit leas its basic function motion detection When motion or movement batteries 24 50 Is detected hoop al is sounded The MOTION Mo h th S NC C DETECTOR designed ww provide either an audible or silent Bene DEM oe vadam Eni There is then additional software in E alarm e silent alarm is contro y a timer which delays 52885 AA NiCad Batteri tof 4 450 the alarm up to 30 seconds The silent alarm activates a relay C 56365 Battery ber foc nba 5 95 the com puter to analyze the portfolio whose contacts are brought out to plug and will activati ANY O 5635 S Completely assembled kit w batteries amp device such ag siren horn tape records elephone dialer etc charger 69 50 and figu re profit and other things The example of Apple brings home a further point Once information
249. t of the CB channels during the past few years may well become a twenty four hour fact of life on the band rendering it useless for anything but close range communications Mo biles trying to talk each other five miles away in New York will find them selves getting squashed by base stations in California on a regular basis Like wise public service stations operating in the 30 to 50 MHz range will find their communications disrupted The sun spot cycle peak will find police cars in Oregon answering calls from a dis patcher in Arkansas and home scan ners in Florida intercepting police calls from Iowa Hams and SWLs will not find the outlook for them entirely rosey though The increasing solar activity will lead to numerous solar flares causing more sudden ionospheric disturbances and ra dio blackouts Further there will be more periods of unsettled conditions due to ionospheric storms caused by charged particles emitted during solar flares Even non users of the radio spec trum will feel the effects of the sun spot cycle peak Displays of the north ern lights will become more frequent and will be observed further south than normal Astronauts in space will have to beware of the X rays unleashed by solar flares The possibility exists for damage to some satellites if the X rays unleashed by flares become intense No matter whether the current cycle has good news or bad in store for yOu it won t be a permanent situation
250. ted Product 100 Day Free Details Conservtek P O Box 35305 Edina MN 55435 BORROW 25 000 interest free indeflnitely Any CES IS report Executive IO11 Box 368 Buford GA 18 GUARANTEED WEEKLY Income of 178 00 35 60 daily working one hour at home Earnings guaran teed FAS Box 13703 San Antonio Texas 78213 BUSINESS OPPORTUNITIES Cont d BUY WHOLESALE Over 1001 gifts and specialty Items details free McCord s Distributors 2932 Cas sell Dr Anderson IN 46012 FREE Details 100 00 Day Possible Buying Scrap Gold Meredith Box 11216VE Reno Nevada 89510 COMPLETE Color Picture Tube rebuilding equip ment with four place oven Top condition Contact MET Reno Box 271 Christina Lake B C Canada V 400 WEEKLY Home mailers needed Send now for FREE details Wilson Combo 1 5211 Fredericks burg 128 San Antonio TX 78229 BUY IT WHOLESALE QUALITY COSTUME JEWELRY BELOW WHOLE SALE Excellent Selection Manufacture Direct IMC Box 336 EB Sylvania Ohio 43560 Closeouts Job es Single Samples Free Details Worldwide Bargain hunters Box 730 IO Holland MI 49423 SAVE MONEY Buy low cost items 5 catalogs 4 00 World Directory 3 00 International Directoiy 3 1001 Things Free 2 00 All 8 10 00 Winchester Enterprises Inc 2807BC Hargrave Street Phila CB RADIO GET a CB Installer s Kit Free You re just 10 days away from making 12 to 25 a
251. tenna catalog a new amateur antenna catalog and a complete accessory catalog 307 Atlas calls their 210X and 215X the perfect am ateur mobile rigs Their 6 page full color detailed spec sheet tells all Yours for the asking 308 Your guide to equipment for radio communi cation is an informative product booklet offered by R L Drake Co Hams and SWLers alike should scan this 20 page shopper s guide 310 New and used personal computer machines and peripherals you never dreamed existed or were available are in the Newman Computer Exchange catalog Get yours today 311 Midland Communications line of base mobile and hand held CB equipment marine transceivers scanning monitors plus a sampling of accessories are covered in a colorful 18 page brochure 312 D Electronic Distributors Inc carries everything from semi conductors to transformer relays to video cameras prices ranging from 19g to 500 products appear from over 125 electronic parts manufacturers The catalog is updated 3 times a year 313 Get all the facts on Progressive Edu Kits Home Radio Course Build 20 radios and electronic cir cuits parts tools and Instructions included 314 Cover the Ham bands from 80 to 10 meters with one classy rig Swan Electronics 100 W 100 MX mobile transceiver Get the details direct from Swan 316 Get the Hustler brochure illustrating their com plete line of CB and monitor radio antennas 318 GC Electron
252. ters are real sports you offer him another game and leap on back to line 310 to pick another secret number You see you don t necessarily need a computer if you get together with a friend and one of you takes the com puter s part Not only will it be fun but both of you will learn Basic Of course if you have a computer you have much greater access to experimentation by changing lines to achieve varying goals Flowcharting will make such experi ments much easier One suggestion Try to have the computer limit the number of guesess given to the human Games Games Games Y ou d like to investigate game playing via computers more fully so where do you turn Right now there are a number of fine books containing programs in Basic for games of varying complexity Some of the books contain flowcharts pro gram runs and or modification sug Continued on page 84 f ELEMENTARY ELECTRONICS January February 1979 H Start here NUMBER A NUMBER GUESSING GAME tts COPYRIGHT PEOPLE S COMPUTER COMPANY BOX 318 MENLO PARK CA 94025 REM REM REM ttt P O 129 HOW DOES IT WORK FOLLOW THE P d go back for a new game go back for new guess REM PRINT INSTRUCTIONS ON HOW TO PLAY I WILL THINK OF A WHOLE NUMBER FROM TO 189 PRINT PRINT PRINT PRINT TRY TO GUESS MY NUMBER AFTER EACH GUESS I WILL TELL YOU IF YOU HAVE GUESSED MY NUMBER OR IF YOUR G
253. test equipment You wil learn and Practice code using the Progressive Code Oscillator You will learn and practice trouble shooting using the Progressive Signal Tracer Progressive Signal Injector Pro gressive Dynamic Radio amp Electronics Tester Square Wave Generator and the accompany ing instructional material d You wiil 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 the product of many years of teaching and engineering experience The Edu Kit will provide you with a basic education in Electronics and Radio worth many times the low Price you pay The Signal Tracer alone is worth more than the price of the kit THE KIT FOR EVERYONE You do not need the slightest background In radio or science Whether you are inter ested in Radio amp Electronics because you want an interesting hobby a well paying yk No Knowledge of Radio Necessary No Additional Parts Tools Needed x Solid State Circuits y Vacuum Tube Circuits ages and backgrounds have successfully used the Edu Kit in more than 79 coun tries of the world The Edu K
254. the SWR meter 3 the antenna tuner and 4 the antenna If you use more than one antenna an antenna switch can be installed before or after the antenna tuner depending upon how many antennas require the use of the The Heathkit HM 102 Wattmeter SWR meter is an easy to build kit that separates the meter and the sensing unit the meter can be placed anywhere up to six feet from the back of the transmitter 37 95 E E Soa CAL eS NORM i OUTPUT i es 4 4 tuner The transceiver or the separate re ceiver and transmitter the TVI filter and the antenna tuner should all be grounded to an eight foot long ground rod outside Use 8 or 10 solid in sulated wire An alternative ground but usually less effective is the cold water pipe system of the house If you are using a vertical antenna with above ground radials attach a wire from the radials to the antenna tuner s ground post Leave the ground wire attached a total of two wires Morse Code The only item now needed to complete your station is a device to send the code You practiced on a straight key to learn to send the code as a part of the Novice license examination As the code tests for the higher grade licenses are receiving only you don t have to stay on a straight key any longer The choice of a straight key an electronic keyer either self contained Continued on page 88 CIRCLE 1 ON READER SERVICE COUPON ere 24
255. the coils are wound in the same direction but the currents are in opposite directions 15 How will the magnetic field produced by current flow in the secondary affect the current drawn by the primary 16 What will happen if the load resistance in the circuit above is increased to 6 500 ohms ANSWERS 12 There will be a current in the secondary when a load is connected across its terminals 13 A magnetic field will be produced by a current in the secondary 14 The secondary magnetic field will oppose that of the primary 15 The secondary magnetic field will decrease the to tal magnetic field acting on the primary and there fore will decrease the impedance of the primary circuit The primary will draw more current 16 Current in the secondary will be ELEMENTARY ELECTRONICS January February 1979 650 volts _ c 6 5000hms 7 1 ampere Power dissipated in the secondary will be 0 1 ampere x 650 volts 65 watts Therefore power drawn in the primary must be 65 watts The current in the primary will then be 65 watts 100 vots 0 65 ampere TRANSFORMER EFFICIENCY So far we have assumed that no power is lost in the transfer from the primary winding to the secondary winding However no transformer has absolutely 100 efficiency Some power is lost in heating the core and some is lost in the resistance of the windings But transformers are very efficient their efficiency often reaches very nearly 10096 Th
256. the dial tone connect the modem this system does not depend on auto dial Then press RETURN several times until the sys tem responds The system will prompt you from then on Any ASCII terminal 110 or 300 baud should work The existence of personal computer networks will make possible for smaller businesses and individuals what larger businesses scientific institutions and the military have been doing for some time computer conferencing y Computer conferencing is not really so different from a conference telephone call except that everyone does not have to be pres ent at the same time A participant can log on to the system follow the discus sion through the messages that have been left by the other participants since he last logged on add his own comments and still maintain a busy schedule A computer conference of this nature gives the participants a different per spective on the proceedings For one thing it does not take place in real time so there is time for everyone to review what has been said and to consider his response It is a cool medium with out face to face contact and it has been noticed that participants have a greater tendency to stick to the topic That does not mean that there can be no whispering with one s neighbor Indi viduals can work out private keywords ware can be quite simple and still be useful or it can be as complex as one desires Digicasting as it is called
257. the output section where the voltage levels from the multiplexer are converted into loudness levels of audible clicks and into brightnss levels of LED flashes The voltage levels are gated through two more analog switch es in ICi1 one for the clicks one for the flashes We ll see how the clicks are produced first The sequence of voltage levels is fed into a signal input of one of the switches pin 8 of ICI1 This switch is turned on briefly during each volt age level by the clock pulses from pin 4 of IC3D Coming out of the switch pin 9 of IC11 is a sequence of short pulses whose amplitudes are the same as the voltage levels from the multi plexer which in turn correspond to the settings of the numbered pots An am plifier consisting of Q2 Q3 and asso ciated components gives the pulses sufficient current to drive the speaker producing a sequence of clicks The loudness of each click in the sequence corresponds to its pot setting A similar arrangement is used to drive the LED with another analog switch pins 10 11 and 12 of IC11 and Ql In this case the analog switch is turned on by pulses directly from IC2 pin 3 which are longer than the clock pulses from IC3 If the shorter clock pulses were used the LED flash es would be too brief and dim Pins from the two unused switches in IC11 pins 1 to 5 and 13 are tied as indicated in the schematic to convenient points to keep them from picking up stray signals
258. the use of the aver age air conditioner owner who would like to save money by avoiding expensive serv ice calls The author tells the reader how to troubleshoot and then shows how to replace defective parts and perform other maintenance on both central and window A practical guide to Repairing air conditioning your air conditioner the easy way Soft cover ed 54 pages LE 5 00 ae EM YOU and YOUR CONDITIONER unit air conditioners Photographs and schematic drawings make it possible for the less experienced do it yourselfers to work safely and confidently from the di rections in this manual Published by Dor rance amp Company 35 Cricket Terrace Ardmore PA 19003 Build a TV Projection System Edmund Scientific is offering a new booklet How ro Design Your Own TV Projection Sys tem Written by Al Nagler an optical de signer it explains how a do it yourselfer using Edmund s Super TV Projection Lens can have big screen television with his own home table top system for as little as 390 Edmund estimates that a contem porary cabinet system can be constructed for about 458 00 a tremendous savings when compared with complete systems Create your own custom SOSH TY projection system with the Edmund f 2 6 Big screen TV for a little price Soft cover 14 pages 1 95 selling today for 1500 to 4000 Con tents of this simplified booklet include Building a Projection TV System Ca
259. tion and checkout you should have a general idea of what the synthesizer does To use it decide how many beats or pots you need for your rhythm this will be the Sequence Length setting Then turn the appropri ate numbered pot up to emphasize a beat down to de emphasize it or off to delete it As you have seen the R amp B Box can operate in two modes either single shot or continuous For the single shot mode set Se quence Length to off In this mode a sequence of all twelve clicks is pro duced each time Reset Start is pushed and released The sequence always be gins from the left with pot 1 If few er than 12 pots are needed in this mode turn the unused pots on the right completely off to prevent unwanted clicks following the end of the rhy thmic pattern For the continuous mode set Se quence Length to one of the numbers 2 through 12 as required for your particular rhythm The pot with that number will be the last one in the se quence The sequence will repeat in definitely once it is started by pushing and releasing Reset Start In this mode the settings of the unused pots on the right do not matter otherwise opera tion is the same as in the single shot mode The fastest way to become familiar with the Rhythm amp Blues Box is to experiment with all the controls There is no way you can damage it by ex perimenting so don t be timid Examples of how to set up various rhythms are shown in the pictorial
260. tion by early 1979 Information about Digicasting and the Digicast Pro ject can be found in the Intellegent Machine Journal 18 year 345 Swett Road Woodside CA 94062 Another similar data base break through is the agreement between Ap ple Computer and Dow Jones to allow owners of Apple II computers to sub scribe to Dow Jones The computer is linked to the service via a modem and a portfolio of stocks is programmed into the machine The computer then monitors the daily stock prices and keeps track of the whole portfolio self for the items of interest With Digi There will not even be any need to and then weget them On standar 7 AMPEX 1 75 4 tor 6 M CS f W ni E AMPEX E ait me Sem of AMPEX 1 0 mil recording TAPE weather gt Ume by government 4 reel D 5588S 7 Burglar MOTION DETECTOR When there is a new development in electronics it takes some The Motion Detector works on a CHANGE OF LIGHT Any change a 57 or qe triggers the Ager Mori eni a j range of 0 1 candlepower almost dark to 1 candlepower time before that development ig available to hobbyists and quite brite range of 1000 to 1 NO external light source is experimenters especially at surplus prices This time we have needed XE us reversed the trend and announce a DELTA EXCLUSIVE the 1 E t DELTA MOTION DETECTOR Thia device detects any motion When lef
261. tions experiments and self assess ment tests Assuming no previous experi ence the text begins with a discussion of how electrons flow in conductors and shows the novice how to read schematic diagrams and component identification codes Three chapters containing numer ous experiments investigate Ohm s Law and DC circuit analysis Proceeding to capacitors and RC time constants the book discusses differentiator and integrator waveforms filters and RC coupling The text explains transformers and inductive coupling and concludes with chapters on diodes and transistors that include clamp and logic circuits zener regulators recti fiers and transistor amplifiers Published by E amp L Instruments Inc 61 First Ave Derby CT 06418 Antique Radio Corner Continued from page 74 are used to keep the signals confined to the transmission lines between pow er stations so that the signals are not lost in the various transformers and oil circuit breakers in the transmission lines Telemetering signals as well as voice transmissions are possible beween power stations This has been a con venient way for utilities to coordinate load requirements among stations in a system During WWII amateur radio op erators were encouraged to try carrier current systems when they were not allowed to transmit over the airways In fact some amateur radio handbooks carried circuit diagrams and sugges tions for its use Many old 1
262. tions are so arranged that a single antenna input can be used Provision is made for an external an COUPON tenna through a Motorola jack or a supplied telescopic whip that pro trudes through the top of the cabinet The whip can be unscrewed when not needed As with the antenna jack the whip antenna serves for reception on all bands All functions and frequencies are en tered through a keyboard having thirty pushbuttons An eleven character L E D display indicates frequency time and all programmed functions Heading the list of functions is a GROUP ON INDICATORS CHANNEL FREQUENCY DELAY PROGRAMMED CHANNEL PRIORITY INDICATOR a ee Se re uu P LOCKOUT ON A typical display Numerals 10 indicate channel 10 is beng monitored D indi cates the 2 second delay has been pro grammed tor the channel meaning the scan will hold or at least 2 seconds after the station goes off before scanning is resumed L means the channel has been temporarily locked out of the scan ning it can be selected manually but not by scanning Finally the frequency read out is 146 450 MHz The five dots at the upper left directly over and to the right of the 10 groups are switched on A P showing before the 10 would indicate the pri ority has been switched on During scan channel 1 will be scanned every 2 seconds r ELEMENTARY ELECTRONICS January February 1979 five band sc
263. tizer It is shaped like a cassette for easy use Suggested price 21 99 Cir cle No 70 Technics is temporarily winning the Watt War with a wild 330 watt RMS per channel into 8 ohms receiver called the SA 1000 Retails for 1500 Circle No 81 Empire Scientific seems to have the answer to gritty grooves a record cleaning liquid that dries and peels off taking dirt with it Retails for 29 95 Circle No 78 S ELEMENTARY ELECTRONICS 27 8 G 4 X amat E 7 Ww m x E ii v i You don t waste a second on mechanics with A P All Circuit Evaluators You figure out the circuit you want then plug itin for testing You decide to improve your layout and you make your moves as quickly as you think them up There s just no faster or easier way to build and test cir cuits and circuit ideas But just because breadboarding is now such a cinch don t get the idea that you don t have electronic integrity Our solderless plug in tie r3 a JE ou omi m 1 a i L m os L Bs M Mane L irat a g a tar ud aa aft a va points are made of a special non corroding alloy Use them as often as you like How many tie points do you need Our smallest ACE has 728 our larg est has 3 648 And all of them acce
264. to the grounded chassis The electric field near the chassis shield is minimal so any pickup by wires is likely to be small As a final precaution keep wiring to low level circuitry separated from high level wiring Inductance Now let s turn to the magnetic field and Figure 4 The most important aspect of this is that there are two current loops a source loop and a receiver loop In the source loop generator drives a current l through load RL The current flow is in turn responsible for a magnetic field that exists in the vicinity of the source if there is no common ground connection between the noise source and receiver electric field coupling may be represented by two stray capacitances C1 and C2 ELEMENTARY ELECTRONICS January February 1979 loop The receiver loop consists of gener ator V2 driving a stage with input impedance RIN Note that no internal resistances are indicated for the voltage generators since such impedances have a negligible effect here In addition a noise voltage VN which is due to source Vi appears in series with V2 If VN is not negligible compared with V2 then we must find ways of minimiz ing the noise pickup What we have in Figure 4 is a sim ple transformer which suggests why magnetic coupling is also known as inductive coupling Alternating current I generates a changing magnetic field that induces a voltage in any loop it intersects As Figure 4 shows the two
265. toplasm your homo sapient inputs his first guess 50 Therefore the variable G now equals 50 In line 440 you compare G with X If they were equal you would jump to line 510 50 obviously does not equal 34 so you just go straight on to line 450 Line 450 asks if the G variable the human s guess is larger than the X variable your secret number Sure enough 50 is larger than 34 so you jump to line 480 just as programmed Line 480 causes you to PRINT that your human guessed too big and should try a smaller number Line 490 sends z 3 4 This book will help explain the program ming concepts behind computer gaming with game examples Circle no 98 for info you scuttling back to line 410 and you get your human s second guess This time through the Joop your human buddy picks 28 Now 28 is smaller than 34 so you ignore line 450 and fall through to line 460 You nudge the user with the info that now he s chosen too small a number Again through the oop and back to line 410 for what is now the third guess Through luck blind chance or divine intervention the human now guesses 34 At line 440 you see that if G X you go to line 510 You print out a congratulatory message after all the E J Join in an amazing underground adventure then use the flowcharts to help you modi fy the plot Circle number 94 for info human does keep you supplied with voltage and as compu
266. ts Sale 1 SALE 1448 2377 1N4001 50 10tfor 75 20 for 76 2378 1N4002 100 10 for 85 20 for 5 2379 1N4003 200 10for 95 20for 96 2380 1N4004 400 10for 1 19 20for 1 20 Amp 2381 1N400S 600 10fer 1 39 20for 1 40 Mini 2382 1N4006 800 10for 149 20for 150 ature 2383 1N4007 1000 10for 1 59 20for 1 60 2 for 1 50 CERMET TRIM 4 for 1 5 AMP POTENTIOMETERS 15 1o s5 20 107 a res 2100 m c7SOlm 232 5K s 0 20K s 200 10 for 79 20 for 80 E sm B d O2K m 10 3 0 250K 400V 10 for 9 20 for 90 m 2 75 2 74 B2 _ IMAGINE GETTING A nd TOR REJECT FOR ONLY PENNY ED RED CALCULATOR GAMBLE LED 126 dig mble of a lifetime you emt styles feature B digits 22 keys 4 arith 1730 SCR s DAIR xi o SK s MM de c 500 Order No 5336 end velue 20 for 2 01 60 for 2 01 400 for 2 01 400 for 2 01 209 lor 2 01 30 for 2 01 200 for 2 01 400 for 2 01 40 for 2 01 50 for 2 01 30 ler 2 01 300 for 2 01 200 for 2 01 400 for 2 01 400 tor 2 01 120 tor 2 01 60 tor 2 01 60 for 2 01 0 for 2 01 20 for 2 01 50 for 2 01 2 for 4 96 2 fer 4 96 300 for 2 01 150 for 2 01 500 for 201 600 for 2 01 18 tor 2 01 200 for 2 01 60 for 2 01 30 for 2 01 180 for 2 01 20 for 2 01 200 for 2 01 50 for 2 01 80 ft for 2 01 6 tor 2 01 20
267. ts for easy installation locks the SO 239 connector in position 8 And the connector is sealed and protected from the elements SWR CHART Big Stick 176 L i1 B L H L T Frequency MH r TALKING DETERIORATION SEVERE ENVIRONMENT 100 95 90 85 80 75 70 65 60 55 PERCENT OF EFFICIENCY NEW 1 2 3 YEARS The principal of skin effect A transmitted Signal in the form of energy travels on the surface of the metal radiator of an antenna This occurs regardless of the length density or thickness of the metal radiator Picture an antenna surface after it has been bombarded by millions of tiny particles day after day Dust dirt pollutants salt chemicals all of them impinging on the surface to create obstacles that offer resistance to your transm tted signal Within six months exposure surface resistance on an exposed radiator can rob you of up to 20 of your power METAL ANTENNA SHAKESPEARE TYPICAL FIBERGLASS ANTENNA A speci of dust It s hell in your eye even Worse on your antenna When it s the surface of an antenna that s designed to radiate the signal yours in for problems Metal corrodes fiberglass does not And the fiberglass surface of the Big Stick is far less susceptible to pollution and contaminants in the environment With a Shakespeare fiberglass antenna surface contamination and crud does not mar performance because the amp s
268. tubes and clean out all the dust dirt and mice corrosion A small air compressor is handy to blow out dust and dirt If there is rust or corrosion on the chassis or other metal parts a small brass or wood a new speaker grill and a cleaned up dial face its value is greatly increased APPENDIX Plastic cleaner and polish small wire brushes glass cutter and tools Brook 127 Vose Farm Road Peter stone borough NH 03458 Small brushes and tools Consumers 109 Wheeler Ave Bargain Corp Pleasantville NY 10570 Tubes parts and schematic drawings Antique Radio Parts P O Box 42 kit or if you prefer a varnish finish you can put on several coats of your favor ite varnish If you are a highly skilled refinisher you may spray on several coats of lacquer If you want the cabi net to be a different color than the bare wood you must first stain it There are many kinds of stain available but I prefer a non grain raising stain because it minimizes sanding If the weather is warm work outside in a spot sheltered from the wind and sun If you must work inside be sure the area is well Treadway s mover Treadway s Refinishing Prod ucts P O Box 1 Lima OH 45802 Rossville IN 46920 Also Puett Elec tronics P O Box 28572 Dallas TX 75228 Power Supplies for old battery radios G B Schneider 6848 Commonwealth Blvd Parma Heights OH 44130 Paint and Varnish Re stainless steel wire brush is use
269. uggested resale price for CSC s Mini Max is 89 95 A number of optional accessories are also being made avail able including an antenna input cables a carrying case AC and automotive bat tery eliminators For additional informa tion contact Continental Specialties Corp 7O Fulton Terrace New Haven CT 06509 Mobile Speaker Acoustic Fiber Sound has a new 8 inch round Model 2831 extended range dual cone speaker that is designed for use CIRCLE 58 ON READER SERVICE COUPON in motor homes and other recreational vehicles cars trucks and for commercial Continued on page 94 WIRE WRAPPING HIT 5 CONTAINS Battery Tool BW 630 Hobby Wrap Tool WSU 30 M PC Edge Connector CON 1 DIP IC Extractor Tool EX 1 DIP IC Insertion Tool INS 1416 PC Card Guides amp Brackets TRS 2 Mini Shear with Safety Clip SP 152 14 16 24 and 40 DIP Sockets Terminals WWT 1 Tri Color Wire Dispenser WD 30 TRI Hobby Board H PCB 1 74 95 ADD 2 00 FOR SHIPPING N Y CITY AND STATE RESIDENTS ADD TAX BOOKMARK BY BOOKWORM Keeping Cool It is amazing how an electromechanical fiuid system can seem so complex to us So much so that we cannot analyze what is wrong with it when it fails You and Your Air Conditioner by Louis J Mangro Jr is a practical guide to air conditioning repair The layman will find easy to follow step by step explanations of what must be done and how to do it This service manual is for
270. understorms And be cause it is free of metal even a leaky cable does not short out The fiber optic line itself looks like a monofilament fishing line but carries light impulses from laser diodes around corners and over several miles without The fiber optic line on the left one inch in diameter equals the capacity of the ten inch copper cable on the right of the photo re transmission t is so small that technicians use microscopes and minia ture electric arc welding unit to splice the tiny fibers How far away is laser cable trans mission from your home It may be within 10 years in big cities where copper mining in the city streets may become big business A specially shielded and sealed mi crowave anechoic chamber at General Motors Engineering Staff is a test cell for developing future automotive elec tronic systems which perform safely reliably and compatibly with electro magnetic fields in the surrounding at mosphere Real world conditions are simulated with test cars run on a dy namometer while subjected to electro magnetic fields Constructed with welded steel walls ceiling and floor the GM facility was designed to protect against outside electromagnetic interference It also prevents the same type of energy from getting to the outside atmosphere dur ing test A GM technician is shown focusing a re motely controlled TV camera on a test car s instrument panel and controls Energy ab sorb
271. urface is not the radiator Instead the radiator is sealed inside the fiberglass sheath which is transparent to radio frequencies and lets the signal through without interference or distortion 8 E 4 pr ried E and True lt gt Built in the factory so you don t have to MS rebuild it on your roof Big Stick comes in two pieces Not like the multi pieced antenna puzzle you helped your neighbor put up last summer You know the one with all those radials and that huge bag of bolts The same one that came crashing down during the windstorm The Big Stick is super engineered 2 Quick easy installation allows you more time to modulate High winds or solid ice it s built to keep you talking whatever the weather v 200 000 square feet devoted entirely to communications antennas and related fiberglass products complete with advanced testing facilities and laboratories for research and development ELECTRONICS AND FIBERGLASS DIVISION Antenna Group P O Box 246 Columbia S C 29202 The Shakespeare Company Manufacturers of Communication Equipment Fishing Tackle Industrial Fiberglass Wonderthread and Specialized Monofilaments Golf Equipment Automotive Products Saddlery and Equestrian Accessories and Marine Taxidermy CIRCLE 25 ON READER SERVICE COUPON aii pr t CIE you ele career trainin from l specialists If
272. usical notations that the Rhythm and Blues Box can t handle sion of a relay when the control input is high the two signal lines are connected together with a low re sistance when it is low they are dis connected An analog switch differs from a logic gate in that a logic gate deals only in highs and lows whereas an analog switch passes any voltage level within limits and passes it in either direction At the beginning of a rhythmic se quence the high in stage 1 of the shift register turns on the first analog switch pins 1 and 2 of IC8 are connected while the remaining switches are off At this time the common output line of the analog switches pins 2 10 3 and 9 of each of the chips IC8 9 and 10 is connected only to the wiper of pot 1 R11 and assumes the volt age level set by that pot At the next clock pulse the high shifts to stage 2 of the shift register which turns on the second analog switch while all others are off The output line is now connected to the wiper of pot 2 R12 and so on down the line As the shift register goes through its se quence a sequence of voltage levels that correspond to the settings of the numbered pots appears on the com mon line ELEMENTARY ELECTRONICS January February 1979 This type of circuit where a com mon line is connected to a series of inputs or outputs one at a time in sequence is called a multiplexer On To The Output The last stop on our tour is
273. utstanding sensitivity extra bright traces selectable triggering 7 position variable time base DC to 5 MHz bandwidth HEATHKIT ELECTRONIC CENTERS PROVIDE SALES AND SERVICE ARIZONA Phoenix 85017 2727 W Indian School Rd KENTUCKY Louisville 40243 12401 Shelbyville Rd Units of Schlumberger Products Corporation Retail prices may be slightly higher Heath Company Dept 139 490 Benton Harbor Michigan 49022 602 279 6247 CALIFORNIA Anaheim 92805 330 E Ball Rd 714 776 9420 El Cerrito 94530 6000 Potrero Ave 415 236 8870 Los Angeles 90007 2309 S Flower St 213 749 0261 Pomona 91767 1555 Orange Grove Ave 714 623 3543 Redwood City 94063 2001 Middlefield Rd 415 365 8155 Sacramento 95825 1860 Fulton Ave 916 486 1575 San Diego La Mesa 92041 E dd Dr 714 461 0110 San Jose Campbell 95008 2 S Bascom Ave 408 377 8920 Woodland Hills 91364 22504 Ventura 213 883 0531 COLORADO Denver 80212 5940 W 38th Ave 303 422 3408 CONNECTICUT Hattford Avon 06001 395 W Main St Rte 44 203 678 0323 FLORIDA Miami Hialeah 33012 4705 W 16th Ave 305 823 2280 Tampa 33614 4019 West Hillsborough Ave 813 886 2541 GEORGIA Atlanta 30342 5285 Rosweli Rd 404 252 4341 ILLINOIS Chicago 60645 3462 66 W Devon Ave 312 583 3920 Chicago Downers Grove 60515 224 Ogden Ave 312 852 1304 INDIANA Indianapolis 46220 2112 E
274. why this is true Many iron vane meters had a resistance of 100 ohms per volt or less This means that a 0 to 100 volt DC meter might have a total of 10 000 ohms resistance This means that it would take 10 milliamps of current to move the pointer to full scale Now let s look at the circuit of the resistance coupled amplifier Sup pose the voltage at the plate of the tube is normally 65 volts This means there is a drop of 35 volts in the 100 000 ohm plate load resistor If you want to measure this voltage with your iron vane voltmeter you will be plac ing 10 000 ohms in parallel with the 100 000 ohm resistor By ohms law for parallel resistors our resistance is less than 10 000 ohms The plate voltage is no longer 65 volts but will measure near zero To get a nearly correct plate voltage reading you must have a volt meter whose internal resistance is much greater than the 100 000 ohm plate load resistor The ideal meter for this is a Vacu m Tube Voltmeter VTVM or at least a meter that has a resistance of 20 000 ohms per volt We will dis cuss the in a future column The conclusion to this example is that an iron vane voltmeter is OK for re pairing battery radios made up to 1927 since resistance coupled ampli fiers didn t become popular until 1929 or 1930 D Arsonval The preferred type for radio work is the D Arsonval or mov ing coil type meter The working parts of this meter are shown in one of the illustrat
275. with a traffic re Lafayette s LM 300 Dual receiver CB set is a great unit to use on the road It lets the user monitor two channels at once Dual LED readouts tell you what channels are on primary and secondary circuits For more in formation on the LM 300 circle number 40 on the reader service Coupon Nes d Lb i wt 1 8 3 4 9a port the LM 300 locks onto the chan nel and I can immediately transmit to get the comflete story Before I get too far ahead of myself let s ake a break and take a look at the LM 300 as it comes out of the box The rear apron is standard with an an tenna connector jacks for P A and ex ternal remote speakers and a power receptacle The LM 300 is a 40 channel mobile rig measuring 2 3 16 in high by 83 in wide by 97 in deep The power requirement is 13 8 VDC with positive or negative ground and power is ap plied through a polarized plug and re ceptacle Standard features include jacks for and remote speaker L E D digital channel indicator both a noise blanker and noise limiter an audio tone control hi cut switch a continuously variable channel indicator dimmer and a plug in microphone Extra features are a built in SWR indicator one meter serves for S RF output SWR the secondary channel selector and a tone alert for the secondary channel selector Okay no more suspense tell you about the secondary channel and its ass
276. y Dartmouth N S B2X 1 GOVERNMENT SURPLUS JEEPS 59 30 CARS 33 50 200 000 ITEMS GOVERNMENT SURPLUS MOST COMPREHENSIVE DIRECTORY AVAILABLE tells how where to buy YOUR AREA 2 00 MONEYBACK GUARANTEE Government Information Services Departmert Eli Box 99249 San Francisco CA 94109 433 California HOBBIES amp COLLECTIONS NEW Electronics Kits for the Hobbyist 1 00 for Catalog and monthly Kit News Hobbi Shack P O Box 235 Jersey City New Jersey 07303 HYPNOTISM FREE Fascinating Hypnosis Information Startling DLMH Box 487 Anaheim California 92405 INVENTIONS WANTED IDEAS inventions new products needed by inno vative manufacturers Marketing assistance available to individuals tinkerers universitles companies with JEWELRY FREE 48 page color jewelry caatlog Russo Box 1106 D Wayne NJ 07470 LOANS BORROW 25 000 overnight Any purpose Keep Indefinitely Write Success Research Box 29253 SM Indianapolis IN 46229 MAGNETS MAGNETS All types Specials 20 disc or 10 bar or 2 stick or 8 assorted magnets 1 00 Magnets Box 192 E Randallstown MD 21133 MISCELLANEOUS NEW occult products including King Tut jewelry Catalog World 7247 1 Eccles Dallas TX MISCELLANEOUS Cont d DOUBLE DUTY ALERT Unique electronic alarm protects against vandals fire Portable or permanent installation Ideal for mobile homes
277. y Orsi Arusa California Name et Please Print Address VS BN a eo apnd O Check here if Eligible for Veteran Training e mmummumummumunmummmmmam 24 Vista Florida Telephone System serving Walt Disney World s 10 000 phones has scored a first by installing a laser transmission system Already possessing the first all electronic phone system the company now has the na tion s first commercial installation of fiber optic phone cable a five mile transmission line using laser beams to send more than 3 300 calls simultane ously over a thumb size cable Digital light impulses carry 672 calls at one time over each pair of glass wires the size of sewing thread The new line running from Vista Florida headquar ters at Lake Buena Vista to a switch ing center near the Magic Kingdom will increase capacity and improve the quality of sound and service on the phone lines which serve hotel guests and company offices ed ka e E w N K AE G xe ever ud on the first commercial in stallation of fiber optic phone cable at Walt Disney World The five mile transmission line uses laser beams to send more than 3 300 calls simultaneously over the cable Fiber optic cable is particularly im portant in an area with a high inci dence of electrical storms since it is entirely non metalic and does not at tract lightning This also eliminates an noying crackling sounds on phone lines during th
278. you face the prospect of around the clock skip conditions which at times may make the CB band al most useless The intense level of solar activity may also cause brief radio blackouts in which all shortwave fre quencies will be rendered useless for communication and spectacular au roral displays in both the northern and southern hemipsheres And the clue that tells scientists how to predict these events are the rapidly increasing num ber of sunspots Sun and Radio Although the sun is over 93 000 000 miles from earth it is the controlling factor in all long dis tance communication at shortwave fre quencies Shortwave radio can cover long distances because the radio waves are bent back to earth in the iono sphere The ionosphere is the region between 60 and 200 miles in attitude that contains many free electrons and ions Under the influence of ultraviolet light and charged particles from the sun the free electrons and ions in the ionosphere combine to form various 34 layers of high ionization If the ioniza tion is dense enough a radio signal from the ground is deflected back to earth by the ionosphere If the level of ionization is not high enough the radio signal passes clear through the iono sphere into outer space Many CBers refer to this phenomenon as skip be cause of the way radio waves skip off the ionosphere Whatever it is called p SUNSPOT NUMBERS 50 PREDICTED
279. ze oniy ix amp x 17 deep clude operation manual THAN Batteries not in PRICE 291 LED cluded Wt 6 z 31 ROOT COUNTER 000 999 resettablas panel mt Lo idia RR R da 1 49 2 tor 1 50 J 2 OUAL GATE MOSFET sim to 34200 3N187 tor RF amp Mixer 1 00 4 1 01 J 2 LCD THERMAL INDICATORS 88 10 F 7x1 flexible l 195 ic Rem Asas 1 00 4 ter 1 01 3 1 JOYSTICK four 100K pote with knob 3908A 4 95 2 for 4 96 1 1 EECO THUMBWHEEL SWITCH BCD 9 7 28 TOA neos e no vie aris rss 1 49 2 tor 1 50 j 1 PLESSEY TV SIDEBAND FILTER for ches 3er s 3979 Lus 1 95 2 tor 1 96 O 2 9V MI CAD CHARGER PAK plug in 125me 125 VAC pri bbba save 1 49 2 tor 1 50 O 20 DATA ENTRY PUSH SWITCHES spat norm tor keyboards 279 2 00 40 for 2 01 D 75 547400 TTL ICs untested SOX4 yield pop types 2415 2 00 180 for 2 01 100 MINI DIP ICs linsers unissted 501 yield pop types 3249 2 00 200 for 2 01 O 30 LM380 AUDIO IC s 2 watts on s dip 50 yield 5204 2 09 60 ter 2 01 7S LINEARS AMPS untested 50 yield amps dips minidips 2419 2 00 150 fer 2 01 100 TTLs amp LINEAR MIXEO with 7400s SOX yield E TR ces adie 200 200 for 2 01 3 1 40 CHANNEL CB SELECTOR w knob fer PLL circuits 2 for 1 01 7 1 23 CHANNEL CE SELECTOR w knob for PLL amp xta
280. ze your alarm system remotely Range 30 Transmitter requiares AA cell not included gA T YT oes Peeled Sh Wt 1 Lb prre ear ee 68 88 3 SPEAKER ENCLOSURES Mfg Closeout FAMOUS NAME MFG had model change amp close out of prod ustion run They might have slight blem ishes or 2nds on the finish Only we d saved big for you shown most are ducked port 3 amp 4 with pop off grills amp tweeters mid range controls on front DP L P 198 00 10 50wt 3 way OP L P 279 50 12 70wt 3 way DP L P 349 50 4 way 12 P R 399 50 Cost 248 B8 This alarm sensor has up to 50 range and fills the protected area with an en ergy screen that cannot be seen felt or heard Triggers your alarm whenever bur glar moves through detector field Moun ts on ceiling wall desk shelf etc Op tional delay mode auto reset or 12 5 VDC A close out that originally sold for 179 00 3Lbs Qty Itd BD3OSUS L owes perc ALSO AVAILABLE 49 88 i Powe a Kit AM FM MULTIPLEX RECEIVER CHASSIS Intended for use in a console by Big Name Mfg AM FM FM multiplex plus phono amp a x inputs building in 115 VAC All solid state Qty Itd Wiring instructions included Sh Wt 3 Lbs AA NICAD 8 PACK Sample picture NEW ea 8 oz pack Cost 118 88 Cost 179 88 Cost 199 88 f T 1 25V pe

e emèñtar - American Radio History

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e em&egrave;&ntilde;tar - American Radio History

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e emèñtar - American Radio History