No. 537 $4.95

ONE PROJECTS BY RUFUS P. TURNER

AUDIO AMPLIFIERS

RF, IF, &DC AMPLIFIERS

OSCILLATORS

CONTROL & ALARM DEVICES

TEST INSTRUMENTS

POWER SUPPLY APPLICATIONS

RECEIVERS, TRANSMITTERS & ACCESSORIES One -Transistor 125 Projects OneTransistor By Rufus125 P. Turner Projects

BlueTAB Ridge Summit, BOOKS Pa. 17214 FIRST EDITION FOURTH PRINTING-OCTOBERTHIRDFIRST PRINTING-AUGUSTPRINTING-AUGUSTFIFTHSECOND 1974 PRINTING-APRIL PRINTING-MAY 19701974 19751972 Preface Copyright 01970 by TAB BOOKSPrinted in the United States of America transistortionOne ofsingle-handedly the circuits shown in all in many virtues of the transistor is its kinds of circuits.this The book are examples of this ability to func- 125 single - Reproductionpermissionrespect to of the orthe usepublication publisher. of the information of is the prohibited. content in any manner. herein. No liability is assumed with without express shouldsilicon,here;usefulness. however, be NPN, able OnlyPNP,to allset a varietiesunijunction, few up and test these circuits with a minimuminexpensive transistor types are represented: germanium,and field-effect. The reader are used PaperboundHardbound Edition: Edition: International International Standard BookBook No. 0-8306-0537-1 No. 0-8306-9537-0 onlyratings;siderationof effort maximum manufacturers'and the and minimum equipment. The circuit designscomparatively take wide spread in typical values were used (or where transistorinto con- Library of Congress Card Number: 72-129045 showncasevalues33Kspecified,minimum of maymust tofrequency determinebea be choice valueindicated, used. -determining was between which used). standard RC and it may be Thus,one where works a 30K best. -ohm However, inis the values werenetworks, specified, the exact the values EIA valuesnecessary of 27K and to try both hobbyistbuildingownstudentperformancereader instruction, blocksshould whosewho wants forclaimed.have amateur incorporationto tolittle the set Theseinterests circuits By following thesetroubleupdesigner and duplicating test whotypical wantsor circuits for his into a system, and to thewill be served by the are offered to the instructions, the betteringready-made the requirements.combinations,combinedpredesigned, (as pretested in cascaded circuits. and so on) amplifiers, oscillator -amplifierto Many of the units suit RUFUS P. TURNERindividual may besystem AUDIO AMPLIFIERS Contents 1 TransformerDegenerativeSiliconGermanium common common-coupled common -emitter -emittercommon -emitter -emitter amplifier amplifier amplifier 141110 9 FETEmitter Commonsource follower follower -source (divider(resistor biased)biased' amplifier amplifier 19161714 ABOUT THE AUTHOR PhaseFiveDriverMicrophoneHeadphone -watt inverterfor powerClass handle amplifier Bamplifier stage preamplifier 23202019 Rufusductor P. field,Turner dating has hadback wide to the experience crystal detector of the 1920s in the semicon- InductorTunedGatedAudio amplifier- -capacitormixer -tuned bandpass bandpass amplifier amplifier 292724 famedandUniversityat1940s. toLos 1N34his HeAngeles, engineering earned ofgermanium Southern hisand B. hisassociation A. California.diode M. degree A. was and developed from California State College Ph.with D. degreesSylvania from when the the there in the transistor RCInductor -tuned -capacitor bandstopbandpass -tuned amplifieramplifier bandstop amplifier 3531 books:articles.Circuits , (1957). HeTheory is the &author Practice of 30 (1954)Dr. Turner wrote two of the first practical books and more than 2500 and Transistor 2 SingleConventionalBroadcastRF, -tuned IF 455 band& 455 -kHzDC RF -kHz IFAMPLIFIERSamplifier IFamplifier amplifier (preselector) 413937 engineer in California and Dr. Turner is licensed as a registered professional Massachusetts. FETDC 455 currentvoltage -kHz amplifierIF amplifier (low-level 4443 DCWidebandDC sourceemitter current follower follower (video) amplifier amplifier (power type) type) 51494845 OSCILLATORS TEST INSTRUMENTS 3 Transformer -tuned AF oscillator (FET)(PNP) 535956 DC microammeter (NPN)(PNP) 118117 Hartley -Type AF oscillator 59 Electronic DC voltmeter 119 PhaseConventionalSelf-excitedLight -shift -operated RC RF audio crystal AFoscillator oscillator oscillator 626064 DipTVGeneral-purpose oscillator field -strength (FET)(PNP) field meter -strength meter 125124123 CrystalSelf-excitedMultiPierce -frequency crystal-type 100 100 oscillator -kHz -kHzcrystal oscillator oscillator oscillator 676572 StepAudioAFDip -type frequencyadapter signal audio injector oscillator meter 132131130 PowerCarrierMicropowerBeat AF -frequency -operatedoscillator AF oscillator AF oscillator (BFO) 757372 StaticRFLCInductance signalcharts detector / (electrometer)capacitance checker comparator 139137135 TVRelaxationPulseMultivibrator sound -generating -channel oscillator oscillator marker oscillator 808280 HeterodyneElectronicElectronicHarmonic load frequency amplifierload resistor resistor meterfor (NPN) frequency(PNP) standards 142142140139 Self -modulated RF oscillator 82 DCCWPhoneAF voltage signal monitor monitor calibrator -tracer adapter for VOM 158148143145 CONTROL AND ALARM DEVICES TunedAFSensitiveElectronic wattmeter AF absorption analyzerthermometer wavemeter 154152151150 4 SensitiveSensitive DC DC relay relay (NPN) (FET)(PNP) 898489 SensitizerBrightMetronome -bulb for stroboscope DC milliammeter 159158157 Heavy-dutyAll -solid-state DC relay DC relay 9190 Circle generator for oscilloscope wheel patterns PhotoelectricTunedACPhotoelectric / RF AF relay relay Relay relay (solar (photofet -cell type) type) 9497 POWER SUPPLY APPLICATION TouchTemperatureHeavy-duty -plate photoelectric relay-sensitive relay control (all solid-state) 102100 6 DCVariable voltage DC regulator power supply (shunt type) 165164162 SignalCoincidenceHeaterCoincidence inverter control relay switch (manual ("and" adjust circuit) ) 102109106 DCDC -to -to voltage-DC -DC inverter inverterregulator (high(medium (low (series voltage) voltage) voltage)type) 169 AudiblePhaseIntervalCarrierVisual alarmshifter alarm-failure timer (lamp alarm flasher) 115113113110 ElectronicConstantDC supply filter -current for tunnel"choke" adapter diodes (high(low level) level) 175172170 7 SimpleRECEIVERS, broadcast TRANSMITTERS receiver & ACCESSORIES 177180 Chapter 1 SelectiveStepDiodeRegenerative -tuned receiver broadcast broadcast with broadcast receivertransistor receiver receiver AF amplifier 180184182 MeterSunAutodyneAll -wave -powered -type regenerativeconverter tuning broadcast indicator receiver receiver 188184 transistorThe single circuits -stage AFand amplifier was ranks Audio one of the first.Amplifiers In this application, among the simplest of LightLightFrequencyCW -bulb transmitter -beam -type doubler receiver tuning indicator 192190 ventionalHerelightthe weight, transistorare aperiodic20 goodaudio typically efficiency, units to offers and low amplifier circuits, ranging from frequency -selective units. In mostmany advantages: small size, power supply demands. con- Code -practice oscillator instancemostbiasedperformanceinstances, often thefor needed), thesebestClass beyond circuit, circuitsA operation.rather the may capability than be cascaded ofWe have endeavored to show obscure ones.typical And in circuits each (the ones a single stage. All are as desired to obtain drawingNPNsomeDepending transistors, power or in on-type. the some specific application,In each of the circuits, unless text, PNP, someon field-effect the basis of (FET), our tests, and iscapacitances offered. are otherwise indicated on the some circuits employ in mfd and tubular)mfd.sincebecause25resistances DCWV.However, many are of Electrolyticusable.theirinreaders other ohms, small Particular willresistors size in types (such as thecapacitors miniature are metallized shown in most circuits, prefer miniaturearea 1/2given watt,electrolytics capacitance, and capacitors such as 1 components from specific are componentcorrectexact1.1-GERMANIUMmanufacturers equivalents, performance having are thewhen ofCOMMONindicated specifiedthe available) circuit. -EMITTER ratings In only when those components (or all otherseem instances, essential to the may be used. any fromvoltageemploying a 12 -volt gain aDC of 2N190 100 at germanium 1 kHz. The maximumPNPFig. 1-1 shows an RC -coupled supply, this circuit provides an common -emitter stagetransistor. OperatedAMPLIFIER input -signal am- open -circuit plitudeRMS and beforeis lv the RMS. the onset Voltage of corresponding maximum output -signal output -signalgain peak is clipping down 3 isdb 10 at 100 Hz and 10 am- my 9 - DC INPUT 12V + particularfrequency response, and higher temperature tolerance. A advantage is the simpler DC base -biasing emitterFig. 1-1. amplifier. Germanium common - SI 0 ON -OFF2.6MAI gaindrain,thearrangement of single this 125 amplifier atdropping 1 which kHz. stage The mayresistor, maximum providesbe used Rl. with aninputOperated the -signal silicon fromamplitude transistor- a 6 -volt DC supply at a 100 open -circuit voltage 1.1a current 3KR2 lvand beforeRMS. the corresponding Voltagethe onset gain of output is maximum3 db -signal down atpeak 70 Hz and 140 kHz. output -signal amplitude is clipping is 8 my RMS The R1 22K 1.0 C3) input1-3-DEGENERATIVE impedance is approximately COMMON 2500 -EMITTER ohms at 1 kHz. AMPLIFIER 1.0 2N190 Q1 current degeneration is In a common -emitter stage, easily obtained byDC omitting INPUT the negative feedback through 6.3K SIGNALOUTPUT + ON 6V1100-OFF - u A SIGNALINPUT R3 1KR4 C2 50 S) 30K 10Cl 2N2712 10C3 1000 ohms at 1 SIGNAL kHz.voltage divider R1 -R3. The DC base bias is obtained Thefrom input impedance is approximately circuit draws 2.6 ma at 12v DC. emitter resistor R4 and 0 INPUT R3 C2 +I OUTPUToSIGNAL circuitinexpensive1-2-SILICON is similar 2N2712 COMMON to the silicon equivalent -EMITTER germaniumThe common -emitter stage transistor. In most respects, this shown in Fig. 1-2 employs an AMPLIFIER circuit in Fig. 1- ad- 470 50 10germaniumvantages:1, but the highersilicon input impedance transistors, transistor offers several worthwhile lower collector than that of equivalent current, better Fig. 1-2. Silicon common -emitter amplifier. 11 DC INPUT Si Q ON -OFF6V 4 100 IA ISIGNAL INPUT SIGNALOUTPUT Fig. 1-3. Degenerative common -emitter amplifier. arrangement,emitter -resistor the same bypass silicon RC -coupledcapacitor. amplifier circuit Fig. 1-3 shows this justcurrentgain.impedance, described Thus, drain, when inand thisFig.1-2 improves operated circuit provideslinearity, anNegative open feedback reduces distortion, minus the bypassfrom capacitor. a 6 -volt DC supply at 100 but it reduces voltage increases-circuit input voltage ma outputgainoutputobtained of impedance40 -signal at entirely 1 kHz. approximately The from input dropping impedance resistorThe maximum input -signal amplitude peak clipping is 30,000 ohms. DC base25 bias my RMS, and is 50,000 ohms and the R1.before the onset of the is correspondingVoltage12to 100 gain kHz. maximumis down 3 db output at 50 -signal Hz but it is constant from 1 kHz amplitude is iv RMS. 13 AMPLIFIER1-4-TRANSFORMER-COUPLED COMMON and output im- -EMITTER DC INPUT + 12V voltagetopedances a transmission gain of ato transistor be obtainedline and amplifier throughalso allows stageTransformer a coupling permits the input the step-up turns ratio of to be matched closely certain amount of ON -OFF R2 ) S1 0.5mA employingthe transformer(s). miniature Fig. input 1-4 andshows output a commonInput impedance and output impedance . in are low(200 ohms); line -to-emitter -line circuit ap- 1.0 Cl 01 10K 1.0 C3 plications,hence,transformeror equivalent) if desired. T2 matches (Argonne Input 200 AR -116, or equivalent) the amplifier may be used ohms to 2000transformer ohms, whereasT1 (Argonne output AR -123, matches 2000 SIGNAL ohmsdrawsemitter to 2.6200 resistor ma ohms. from R3 theBoth and 12 are -voltvoltage miniature DC supply.dividerThe R1 2N190 transistor receives its DC Withtransformers. the transformer -R2.base The bias circuit from INPUT R1 C2 OUTPUTSIGNAL50 coupledinpedanceplitude1 kHz circuit,(comparebefore ratios the shown,Fig.1-1). onsetthis the withof Theopen output the gain-signal peak maximum-circuit voltage input gain -signal is 2000 am- at of the equivalent RC - clipping is 1 my Fig. 1-5. FET common -source amplifier. RMS,1-5-FETtude andis 2v theCOMMON RMS. corresponding -SOURCE maximum AMPLIFIER output -signal ampli- DC INPUT 1311A 611 circuit1000its high megohms to input look impedance. like in junction that of This a-type vacuum impedance FETs) tube. Thecauses Consequently, great advantage of a field-effect transistor (characteristically, the FET input (FET) is the R1 S1) ON -OFF withandFETmicrophone.This FET amplifiera highmeans stages -impedance imposesthat may an be FET virtuallycascaded amplifier no with no may operate transducer, load on the signal source, such loss of voltage gain. as aefficiently crystal 10Cl 2N190 ployingcircuit a 2N3823 is equivalent junction to-type the commonFig. 1-5 shows a common -source FET. The common -source FET -emitter-cathodeamplifier conventional vacuum circuit -tube -em- INPUTSIGNAL R2 C210 dropbiascircuit.transistortube (comparabledeveloped cathodeplateAs circuitin current).a tube resistor)across andto circuit,tube to Thethe theR3grid source theinput commonby bias) FET drain impedance entirelyhere current (comparable resistor (comparable to a receives its DC gate fromof the the voltage circuit is to 1K OUTPUTSIGNAL 14ohms.pedanceequal to isthe equal resistance approximately of R1, 5to megohms; the resistance of R2, 10,000 the output im- Fig. 1-6. Emitter follower (divider biased). 15 -DC INPUT 6V + signalmaximum peak input clipping -signal amplitude before is iv RMS and the the onset of output corresponding - S1 ,, ON -OFF 2MA responsemaximum is flatoutput to 100 -signal kHz andamplitude down 3 isdb at 100 Hz. 0.95v RMS. Frequency Ci R1 I 1-7-EMITTER FOLLOWERA somewhat higher input impedance(RESISTOR can be obtainedBIASED) in a 2N190 circuitgermanium shown emitter in Fig. 1-6 follower is if the divider replaced with the single -type base -bias dropping 10 C2 transistors,thethisresistor, 1500latter R1, ohmscircuit, however, shown of for inthe theFig. resistor 1-7. The method i-kHz of example, is 20,000 ohms, previous circuit. With input impedance of biasing does comparednot with germanium 0 INPUTSIGNAL R2 S 1K 10 SIGNAL supply.fordedprovide by At the voltage 1 temperaturekHz the-divider maximum stability input of theThe circuit in Fig. 1-7 draws biasing. 2 ma from the 6 -volt DC operating point af- OUTPUT correspondingthe onset of output maximum -signal output -signal peak clipping is lv RMS and the -signal amplitude before DC INPUT amplitude is 0.96v Fig. 1-7. Emitter follower (resistor biased). 1.7MA9V outputkHz, the -signal maximum output -signal amplitudeThe before circuit draws 0.5 ma from the 12 -volt DC supply. At 1 peak clipping is 0.15v RMS, the onset of and RMS. the Q1 S1 ) c ON -OFF -I correspondingmanner,control,The 1-6-EMITTERopen may -circuit maximum be substituted voltage FOLLOWER output gain -signal accordingly (DIVIDER amplitude isBIASED) 13.3. is 2v For gain a , connected in for resistor R1. the conventional 1.0 Cl 2N3823 pedancevacuum -tubeconverters cathode having follower; power gain.The transistor emitter -follower circuit is equivalent to the both are high -to -low im- The emitter follower INPUTSIGNAL R1 5M O 1.0I(C2 is impedanceconvenientfromresistor2N190 the transistor R3 6load,for -volt and matching without DCvoltage which supply. athe receivesdividerhigh inconvenience The -impedance Ri-R2.inputits DCFig. impedance baseCurrent source1-6 bias shows drain tooffrom athe an isemitter circuit emitter3 ma -follower circuit employing a of a transformer. low - R2 1K OUTPUTSIGNAL 16is 800approximately ohms. 1500 ohms at 1 kHz andThe the openoutput -circuit impedance voltage gain is 0.95. At 1 kHz the Fig. 1-8. FET source follower 17 OutputFrequencyRMS. Theimpedance response open -circuit is is 520flat toohms.voltage 100 kHz gain and accordingly down 3 db at is100 Hz. 0.96. circuitfollower.impedance1-8-FET which The SOURCE isconverter, equivalent advantage FOLLOWER the to arrangementofthe the emitter FET follower is isWhen its a source aand field-effect cathode-follower transistor is employed in a very high input high -to -low DCpedancethis2N3823impedance, supply. circuit junctionis The560 is comparable equalohms.DC -type gate toThe FET. R1, bias tocircuit 5Atthat is megohms, 1obtained drawsof,kHz a vacuum the1.7Fig. and inputma 1-8 fromthetube. shows the 9 -volta source -follower circuit employing impedance of output im- a onsetthedrainvoltage conventional current.of drop output produced For manner,-signal gain across control, peak source clipping a resistor Atis lv 1R2 kHzRMS by thethe and maximumflow of input -signal may be substituted for resistor Rl. potentiometer, connected in amplitude before the entirely from the the 1-9-HEADPHONEFrequencyRMS.corresponding The response open maximum -circuit AMPLIFIERis flat tovoltage output 100 kHz gain-signalA and simple, down amplitude low 3 db -powered at is 50 Hz. amplifier sometimes is needed to accordingly is 0.7v0.7. headphones.tocommonamplifier boostthe signal a -sourcecircuit.signal source, for Employingcircuit, headphone yet this develops aamplifier 2N3823 operation. junctionoffers AtFig. 1 virtually1-9kHz -type shows the FET inputno such loadin impedance a of the circuit is a strong signal in the an supplyaccordinglyacrosscorrespondingonsetmegohm. ofthe and output 2000The isthe 60. maximum -ohm-signalDC The gate headphones circuit peak outputbiasinput drawsclipping is -signal -signal obtainedis 2.13v isRMS.ma amplitude50 from entirely my The theRMS voltage developedbefore9 from -volt and gain theDCthe equal to R1, 1 pairresonantmagnetic currentvoltageof Trimm circuit headphones flow.drop with2000 produced the -ohmwith inductance aacross headphones,suitable source of capacitor theAudio resistorfor (Cx) selectivity R2 to by form the drain may be obtained by shunting headphones. With a example, the the a 18 withHowever,frequency individual someresponse headphones.adjustment peaked ofat the1 kHz capacitance when Cx will be was 0.005 mfd. required 19 Cl C3 1.0 2N3823 R3 1.0 f -- MIKE 5M Si 1K ON -OFF SHIELDED CABLE ELEMENT R1 300R2 C2 -10 Bi 3V 3.4MA 1-10-MICROPHONE-HANDLE PREAMPLIFIERDue to its small size and ability to operate from one or Fig. 1-10. Microphone handle preamplifier. two microphone-aclosepenlightfromlevel a selftwomicrophones cells, -powered1.5v decidedthe penlight transistor preamplifierto convenience existing cells hasconnected speech in the handle inamplifiers.Fig. series. 1-10 is a schematic of such an amplifier, made it practicable to en-in adapting certain low- of a lowThe -output high input rperated loadingimpedancemegohms.supply.this amplifier the of latter. Thethe to 2N3823 output Thebe used circuit impedance with any type ofAt microphone1 kHz the input impedance of the circuit is equal field-effect transistor (Q1) enablesdraws 3.4 ma from the 3 -volt DC is equal to R3, 1000 ohms, withoutto R1, 5 andmaximumsignaland iscircuit lowof peak couplingenough voltage inputoutput clipping to-signal gain intominimize-signal is isthe amplitude 0.4v5. amplitude main problems amplifier. before is 2v the onset RMS and the corresponding of stray -signal pickup RMS. The open - At 1 kHz theof output - pushpull1 kHz1-11-DRIVER and amplifier draws 2.6FORstage. ma CLASS fromThis the -B 12 STAGEFig. 1-11 shows the circuit of a driver delivers 12 mw output at -voltClass DC A driversupply. for a Class B 20base bias from emitter resistor R3 and voltageIn this arrangement, the 2N190 transistor receives dividerits DC R2 -R4. 21 outputDCandpotentiometerBlocking componentcoupling transformer, capacitor capacitor arriving R1 from T1 C2Clfrom grounding is needed the (Argonneprotects AR -175, the or input circuitthe from signal source. The miniature to prevent gain -controlbase of the transistor, any inputonsetpushpullmatches of-signal output base the voltage2000-emitter -signal -ohm the Class collector amplifier B At 1 kHz the maximum peak clipping is 10 my RMS. input -signal amplitude before thecircuitinput to circuit. the typical 1500 -ohm delivers the full 12 equivalent), At this mw amplifier1-12-FIVE-WATToutput which (e.g., pushpullis more POWER than 2N109s) sufficient AMPLIFIER from toThe Class A circuit shown drive a typical175 to Class200 mw B output. speakergainsignalpower of oftransistor 2000. or2.5 for mw Such various towill andeliver resultamplifier servo 5 in watts andthe full toIn this arrangement, transistor Q1 receives its DC mayin Fig. be 1-12 used employs to drive a loud-control an 8 5-ohm watts load. output, An input a purposes. a 2N301 power base collector(Chicago-StancormatchesR1bias -R3. from circuit theInput unbypassed 500 to transformer an-ohm TA 8 -ohm -12, emitter or The circuit draws 901 input to 50 ohms; output transformer T1 (Knight 54A2373,load. All equivalent) matchesresistor the 20 R2-ohm and voltage divider are 1 watt. or equivalent) T2 that2N301transistorheatrepresents mustsink is internallymustbecool. aremembered continuous beFor connectedthis DC provided (as shown in Fig. 1-12) to purpose the collectormawhen from electrode attachingthe 12 of -volt the the powerDC heat levelsink of 10.8w, so a tosuitable the mounting flange, a fact supply. This keep the circuitsmounting1.13-PHASE and the grounds. transistor INVERTER on Fig. 1-13 shows the circuit of a metal chassis to prevent short a paraphase-type phase in- and in inputsignaltakensistor,verter. signal. input,output from performsThis Thedue the2, simple taken twotocollector, wellthe circuit,from at audio isthe action output signals thus are 180 degrees out of 180 employingdegrees out a of 2N2712 phase withsilicon the tran- emitter,frequencies. is in Signal phase outputwith the 1, of the transistor, whereas 22 resistorthephase same with R3 arerespect closely to each matched other. amplitude if collector resistor R2 and (the absolute resistanceThe two outputvalue signals have emitter 23 DC INPUT+ (9V, 0.6MA) ON -OFF oSlI - 4.7 K + C2 2N2712 1.0I OUTPUTSIGNAL 1 0 INPUTSIGNAL ++( 1.0 C3 OUTPUTSIGNAL 2 3 L 4.7K COMMON 0 is relativelysame resistance). unimportant, so This type of phase inverterFig. is 1-13. basically Phase a inverter. long as both resistors have the identicalfollowercommonbase bias -emittervoltagefor is signal obtained amplifiergain. output through 2, The circuit draws 0.6 ma from for signal output 1 and an emitter270K dropping withresistor both R1. amplifiers At 1 having the 9 -volt DC supply. DC before the onset of kHzsignalmaximumoutput isthe 0.98. maximumoutput-signal Input output 1 peak orimpedance input signal-signal clipping -signal output amplitude is amplitude 50,000is 1.7v RMS and the corresponding2. The open -circuit voltageohms at gain1.kHz. is 1.67v RMS for either 241-14-AUDIO MIXER A 3 -channel -input audio mixer circuit is shown in Fig. 1-14. 25 DC INPUT (6V, 0.4MA) The maximum input impedance (all three gain controls- areR1,impedance1-megohmlookingR1, used,R3, R3, and the into and mayR5 inputpotentiometers any andR5-set be pair impedanceisolatingobtained toof maximumsignal resistorsandby becomes 1-megohm 0.667 input terminals.increasing Higher input the resistance of gain)R2, R4, and R6. Thus, if isolatingis resistors 0.328 megohm actually1-15-GATEDoutput a standard impedance AMPLIFIER common is equal -emitter to R7, 10,000Fig. ohms.1-15 shows the circuit of a simple gated amplifier, amplifier employing a megohm. The SIGNAL emittermade2N2712 for resistor applyingsilicon R3. transistor, a DC but For a constant AF input gating, or control,-signal voltage voltage,one the in output which provision has been -signalacross 0 SIGNALINPUT OUTPUT voltageautomaticlargerhigherandvoltage amplifierfedthe will isvoltage,gainback cutproportional control. theinto whichtheamplifier lowerDC Also, thisto control theoffthe unit DC is control a sufficiently high DCoutput. control Thus, thesignal output input of a terminals fora stage may be rectified -signal voltage; the 1basegategoing kHz (switch)bias thesquare ismaximum obtained thewave amplifier or step onfunction and off ofThe circuit draws 0.4 input -signalthrough amplitude 0.7-meg before dropping the onset resistor of Rl. At ma from the 6 -volt DC completely. Thus, a positive - as required. proper magnitude will supply. DC DC CONTROL SIGNAL INPUT Fig. 1-15. Gated amplifier. currentkHz.circuitoutputing A maximum voltage -signalDC off controland peakgain reduce output isclipping 6.67. the-signal is 0.15v signal of 6v will cut the transistor Input impedance is 50,000 ohmsamplitude at is lv RMS. The RMS and the correspond- collector open - 1 loadaThe highcommonthe 2N3823 to 1/2-megohm input signal signal impedance,junction sources output input -type (such so gainis field-effect thatthe as controls microphones)blend transistorof (R1, R3, beyond (Q1) provides the circuit offers virtually no the three individually and R5). The that of andvoltage,thisresistorisolationfunction willwill (dotteddue of draws the to thecontrol Rx 3.6 voltage in division cause a proportionate reduction in ma from the DC control -voltage-voltageFig. 1-15) source may is be desired, installed. an output signal to zero. The control across Rx and R3 in series, applied control However,source. If isolating gatecontrolledsignalmaximumflow bias of peak isdrain input obtained input clipping current signals. -signal from through is amplitude 0.15vthe voltage source RMS before resistor dropandThe the circuit R8. onset At draws 1 0.5 ma from the 12 -volt DC supply. the correspondingproduced by the of output - kHz the DC source.1-16-TUNED-TRANSFORMER BANDPASSTuned AF amplifiers require a proportionately higher peaked at a single frequency AMPLIFIERcontrol -voltage are circuitmaximum26signal voltage input output terminals. gain -signal is 13.3. amplitude This applies is 2v RMS. to either pair The open - of struments,anduseful MCW as active and electronic control radiotelegraph reception, electronic bandpass filters in bridge null applications. Amplifiers of detectors, CW musical in- 27 describedthis type in the are shown in In Fig. 1-16A, the corresponding sections. Figs. 1-16, 1-17, and 1-19 and are CI-zU, primarycii cuit windingconsisting of of capacitoramplifier C3 is andtuned the by inductance a miniature output paralleltransformer resonant of the T1 CC1 shown(Argonne here ARtunes -109, the ortransformer equivalent). The to approximately 0.003-mfd capacitor 1 kHz cr)s-a) 1-4 transformer.capacitance(Fig. 1-16B shows will For requirehigher the some amplifier frequency frequencies, reduce the adjustment with an individual response), but the I - 1111111111111111111111M111111111111=rilagal===1:41AVAsmunismomommumora mum for lower frequencies, The circuit employs increase it. a 2N3823 field-effect transistor capacitance; in a 12 - 7a) I 1 I 11111111111111M111111111 Thedevelopedvoltcommon input DC supply.impedance across-source DCsource amplifier. is resistor Current R2 gate bias is obtained from the equal to the resistance of drain is 2.6by mathe fromdrain the-current flow. voltagegain control drop M cr LC) 1111§1111111111111111111111111W0.1111111111111111111111111111111111111110111111111 signalR1, 1amplitude megohm. before the onset At the 1 -kHz resonant peak the maximum of output -signal peak clip- input - O CDCD signalping is amplitude 30 my RMS is 1.5v and RMS. the The corresponding maximum output - U)O (-I 0 O 11111111111(S110A sw) i(1dino 1VNDIS O .-4 AMPLIFIER1-17-INDUCTOR-CAPACITOR-TUNEDthe resonant peak is 50. open -circuit voltage gain at BANDPASS CD Somewhat better selectivity than that afforded by the 0Ea) Li - frequencywithamplifier the bandpass response described is inshown the in In this circuit, the amplifier circuit shown in parallel resonant circuit whichpreceding Section Fig. 1-17B. may be obtainedFig. 1-17A. The tunes U V4. a)ro 47- Ea) feedbackequivalent).adjustable,the amplifier loop 5 This between consists-henry LC inductor,combination Li of capacitor C2 and the collector is inserted(U. T. intoC. Type the VI a miniature, high -Q, negative-C15, or L.) rI frequencyofbase the input (actually, circuit of a parallel -resonant combination the 2N190 transistor. The narrow band of frequencies) from output circuit (L1C2)and the removes one wavetrap action the frequencies.effectivelyhowever,mitsfeedbackfed -back a signalnegative at The that of net feedback result signal voltage. Consequently,prevents frequencythat andfrequency. the amplifier At all transmission is the sharplyreduces the amplifier of there is no negativesignalsother frequencies,peaked bandpass readily trans- atgain and those 28 mayresponse be tuned shown precisely. in Fig. The 1-17B. Since the inductor is screwdriver adjustable, the specified inductor, for example, amplifier 29 it Hzthatis adjustable to if 1370 C2 is Hz. 0.005from For 2.7mfd, higher the hy to 6 hy, approximately, which obtainable frequency range is 919 means O transistor.passagenotfrequencies, a part of of DC increase the from resonant it. the The collector 10-mfd back frequencies, decrease C2; forcircuit, lower but serves to block the coupling capacitor (C3) is to the base of the -1O LLJ dividerbase bias R1 is -R3. obtained At the from1 -kHz The circuit draws 1.6 ma from the 12 -volt DC emitter resistor R2 and supply. DC voltage 11§passinapits111101111iineasa zLuCLLei amplitudeclippinginput -signal is is30 amplitude3v my RMS. RMS, Thebefore and the the 'onset resonant peak, the maximumcorresponding output -signal of output -signal peak CO ro resonantAMPLIFIERLIS-INDUCTOR-CAPACITOR-TUNED peak accordingly is open -circuit voltage 100.gain at the BANDSTOP slion) Indino 1VNDIS e-4 O Ca.U) suppression,as AFactive amplifiers tuned to bandstop or band -elimination filters reject a single frequency are useful (also filters)called notch,in harmonic band - ronnumwmias MUM= 4-V C(1) plifiersradiotelegraphy,distortion of this meters, type and are interference electronic shown in control eliminators,Figs. 1-18 CW andand 1-20MCW and are applications. Am- 4- as0 circuitdescribed consisting in the of In Fig. 1-18A, the corresponding sections. amplifier is tuned by a series resonant 00_0 thebasefeedbackequivalent).adjustable, input loop circuit 5This -henry between LC of thecombinationinductor, the Ll is(U. inserted T. series -resonant capacitor C2 and a miniature,2N190 transistor. The collector output circuit and (L1C2) C. Type VI -C15, or into the negative pass action of high -Q, the r -I O C thefrequency feedback (actually, a narrow band path, and ideally removes all combination of frequencies) transmits others. Con- through one CI CIO U 18B.resultotherandsequently, its frequenciesis output the the notch ideally amplifier gain is cancelledAs in the bandpass -typeare transmitted frequency responseby the shown inreduced to zero, whereasamplifier described in the amplifier.at Thethat netfrequency signals at all Fig. 1- O C2;rangewhichexample,amplifierSection for ismeans lower919 may1.17,is Hzadjustable that be sinceto if tuned1370 C2 the fromHz. For 2.7 frequencies, increase it. In this inductor isis screwdriver 0.005 mfd,precisely. the obtainable The specified inductor, for higher frequencies,hy to decrease 6 hy, approximately, adjustable, the frequencypreceding 30 transistor.passagecapacitor of C2 DC also from serves the as collector a back blocking capacitor to prevent the to the base of the circuit, tuning 31 0.1 1( C5 R6 796 0.1 )H--C6 1592 R7 C7 0.2 '= 1592 R8C3 10 ilialliarnarMEMEminosimummaiiiisiMMINsommommommimumanimmimomm Ammon. 410LA' 1M 2N190 R5 5K ) C410 Nimmommommommimmimmiumum SIGNAL INPUT CONTROLGA0 100 K R4 S1 SIGNAL OUTPUT 0 11011111111111 R2 10KA CIRCUIT R3 1K C2 50 / DC INPUT (12V, 2.5MA) ON -OFF I

100 1K 10K SIGNAL INPUT = 0.2V RMS Fig. 1-19. RC -tuned bandpass amplifier. FREQUENCYB (Hz) RESPONSE 32 33 thedividerbase 1 -kHzbias R1 is resonant-R3. obtained At some from distance The circuit draws 1.6 dip, say 10 kHz, the maximum ma from the 12 -volt DC emitter resistor R2 and to the high -frequency side of input -signalsupply. DC voltage 1-19-RC-TUNED2.9vmyamplitude RMS RMS. andbefore At thatthe theBANDPASS correspondingpoint, onset the of The circuit shown in open -circuitoutput voltage -signalAMPLIFIER gain peak is 96.7.clipping is output -signal amplitude is 30 responseresistancesHowever,amplifiersbasically, of theand itdescribed andusescircuit three serves no is inductors; shown the in capacitances.previously inThe Sections bandpass 1.16 and same applications as Fig.the 1-19A operates the instead,Fig. 1-19B.it is tuned by three frequencybandpass same, 1.17. removestransistor.collectorR8) is inserted one Theoutput frequency notch intocircuit the and In this circuit, a twin -T (or nulling) actionnegative of the -feedback loop betweentheRC base null(actually, input network circuit (C5 of-C6 a narrow band RC circuit-C7 -R6 -R7 -the 2N190 the of thoseplifierfrequencies,readilynofrequencies) negativefrequencies. gain transmits and however, effectivelyfeedback from The a the signalnegative feedat that of -back net result is the prevents transmission of signals at that frequency,frequency.voltage. soAtfeedback the all As amplifier a result, reduces there the is other am- 11111Z.1111111111111111111111601111111111111111111111111 Here,thepass capacitances C5 response equals C6 shown equals in Fig. 1-19B. The notch frequency of (C5, C6, C7) and the resistances the twin -T network is sharply peaked band- (R6, R7,governed R8). by 111111111i1111111111111111111111111L111111111111111111111111111011111111111111111111111.111:1111111.11111111 microfarads,frequency,R7For is1 -kHz1592 f ohms,equals and R7 R8 106 in ohms. operation, C5 is 0.1 mfd, C6 is 0.1 is 1592 ohms, and R6 is /(6.28C5R7), where f 1/2C7,is in and R7 equals R8 796mfd, ohms. C7 is 0.2For mfd, equals 2R6. Hz, C5 in any 1111111111111111111111IIIII1111111111111111111111111111111111/A111111111111111111111:1110:411111111100 1K 10K SIGNAL INPUT = 1.4V RMS R2biasmust -R4. is obtainedAtbe the carefully 1 -kHz from selected The circuit draws 2.5 emitter resistor R3 and ma from the 12 -volt for exact values. The capacitors and supply. DCvoltage base divider resistors FREQUENCY (Hz) B RESPONSE RMS.0.2vamplitude1-20-RC-TUNED RMS The and before the the BANDSTOP onset of open -circuit voltage gain at the corresponding output -signalresonant peak the maximum AMPLIFIERoutput -signal peak clipping is resonant peak is 5. amplitude is lv input -signal 34 Fig. 1-20. RC -tuned bandstop amplifier. plications as the The circuit in bandstop amplifier described in Fig. 1-20A serves the same basic ap- Section 1.18. 35 areintoresistancesHowever, thea bridged two (R1,it sectionsuses -T R2) null no and (notch) inductors;of two a ganged capacitances network. rather, 10,000 Resistances it(C2, C3) R1 -ohmis wirewound tuned by two connected and R2 potentiometer.removesoperatesinsertedselected at forasone the aexact frequencycommonCapacitorsinput values. of the -source (depending 2N3823C2 and amplifier, field-effectC3 uponIn thethis transistor setting circuit, the bridged -T null network (R1 -R2 -C2 -C3) is must be carefullyand this network of dualwhich Chapter 2 potentiometermaximum0.01responsenetwork mfd ofoutputand to the R1 minimumC3, complete is-R2) 1 amplified mfd, from resistance varying the and applied potentiometer thevaries notch inputthe -typenotch signal. R1 frequency frequency-R2 circuit resembles Fig. 1-20B. If C2 is from The frequency,The transistor intermediate is eminently -frequency, useful and direct RF, IF & DC Amplifiers in single -stage radio -current am- - 20,000fromthereselectiveto -200200 Hz is HzHz virtuallyby RC to bymaking 2000 networkmaking noHz. C2 loading C2This 0.001is 1followed tuningmfd mfd to and upset andrange byC3 C3 thea10may field-effect0.01 mfd,selectivity be changedand to transistor, 2000(loading to 20 -to - - mfd. Since the capableitandinterestingplifiers. is 2.7)a true ofsince,The inoperationcurrent conventionalsome unlike DCamplifier. afar vacuumapplications into (bipolar) the Moderntube radio (as transistorIn shown this Chapter in is a collection of or field-effect transistor, spectrum.RF transistors are is especiallySections 2.6 isresulting resistorgateoffinherentnegligible). resonance. bias from R4,attenuation is the obtainedTheresulting 1-megohm amplifier of from thefrom bridgedgain partiallythe drain -controlvoltage -T-current compensatesnetworkThe potentiometer drop circuit flow. acrossat frequenciesdraws Atfor source (R3)some the1.1 ma from the 12 -volt DC supply. DC fromareresistancesonfrom theratedspecific many drawing to withstandintested. manufacturers ohms, or Inin resistors eachathe DC text, Particular components are circuit,working unless voltage otherwise of 25v. indicatedare 1/2specified watt, (orcapacitancesand only exact all whencapacitors equivalents, those are in units mfd when and amplifier circuits selected point,thebeforedistance(notch), corresponding thethe to openonset saythe low100-circuitof output -frequencyoutputHz, voltage the -signal -signal maximum sidegain peak amplitude of is clipping the0.643. input 1 -kHz is-signalis 1.4v 0.9v. resonant RMS amplitude At that anddip (PRESELECTOR)2.1-BROADCASTspecifiedcuit.available) ratings seem essential may BAND be used.to RF correct In all other instances, any AMPLIFIERcomponent having the performance of the cir- kHz.haspreselector1. a This 20 -kHz unit in isbandwidththe standard broadcast bandA tuned radio -frequency continuously tunable from 500 to 1700 kHz and (between 3 db 0.707 points) amplifier suitable for use as a is shown in Fig. 2- at 1000 pedancespowerinputapproximately -signal gain are of amplitude 1020 madb infrom isthe the 6 -volt DCShieldingEmploying of the a 2N169Ainput (L1 NPN -L2) transistor,and the approximately 500 ohms each. 300 my RMSamplifier. for an undistorted Input and output im- output (L3 -L4) trans- supply. Maximum circuit draws 36 shielded,whichformers otherwise is would tapped -coil RFnecessary transformers to prevent in the amplifier, need to be neutralized. may be used or the Commercial, 37 P CC_J I- CL- coils may be wound with No. 32 enameled wire on 1 -inch ...... (1) 1- ...... theelectrically,ganged;diameter rotors however,forms must or the according be DC thelinked circuit rotors to by Table willcannot be 2-1. short-circuited. beThe two sections (C1, C2) of the means of an insulated shaft tuning capacitor areconnected together Instead, coupling. The entire tuning capacitor assembly must be in- sI . sulated from a metal chassis, if one is used as a foundation for I c_.) the amplifier. It is for these reasons that a standard 2 -gang J ta.1 Lt. Ua)a)(r)cr) frequenciestuning capacitor if the tuned cannot circuits be used. are This RF amplifier circuit may be operated at higher proportioned accordingly O + a)L and a high -frequency transistor TABLE 2-1. COIL TABLE FOR R -F type selected. AMPLIFIER L.) CD E0no lowerL1-10 end turns of ofL2 No. and 32 insulated enameled from wire the latter. closewound around the 130CD diameterL2-130 turns form. of Tap No. 15th 32 enameledturn from thewire lower closewound on a 1" - end. r CDVo diameterL3-130 turns form. of Tap No. 80th 32 enameledturn from thewire lower closewound on a 1" - end. cLri0 lowerL4-12 end turns of ofL3 No. and 32 insulated enameled from wire the latter.closewound around the coupled2.2 -CONVENTIONAL intermediate -frequency 455 -kHz IF amplifierAMPLIFIERFig. 2-2 shows for the circuit of a conventional, transformer 455 -kHz - dividerbasedrawsoperation.formers bias approximatelyR2 is-R3.(T1,T2) Employing obtained are from10core a 2N394ma tuned.emitter from PNP (T1 the transistor,The miniature, the tapped, stepdown, 455 -kHz IF trans- input:resistor J. R4W. andMiller voltage Type6 -volt DC supply. DC circuit (say,connectedprovidedequivalent.)2041, 10.7 byto MHz) thea Neutralization, 30-pf correct by miniaturesubstituting end of the toceramic T2preventThis IF amplifier circuitor equivalent, T2 output: may be used at higher frequencies J.secondary winding. W.capacitor Miller (C4) when oscillation, 2042, oris 38 frequencyformers for transistorthe 455 -kHz units and type. by selecting a suitablehigh high -frequency - IF trans- 39 the one2.3-SINGLE-TUNED described in 455 -kHz IFA 455 -kHz IF amplifier which is somewhatFig. 2-2 is shown in Fig. AMPLIFIER simpler than struments,plicationstunedandcircuit although circuit,employs etc.). itits hasonly lower Employing a 2N394 PNP (simple radio receivers, response is adequate for a numberone tuning unit, output selectivity than that of the heterodyne transformer Ti;2-3. This latter test double - of ap- in- capacitortoR2.is approximatelyobtainedbe The neutralized miniature is fromconnected 1.5 emitter totrimmer ma to from the the 6 -volt prevent IF oscillation, resistor R3 and capacitorcorrect (C2) allows end of thethe circuitT1transistor, the circuit draws DC supply. DC base voltage divider R1 - provided the secondary bias suitablefrequencyfrequenciesT1winding. (J. W.high transformer TheMiller (say, miniature is substituted This amplifier circuit Type 2042, or equivalent) is 10.7 MHz), provided stepdown 455 -kHz output also may be used atfor higher the 455 -kHz unit and core tuned.a suitable high - transformer, a -frequency transistor is selected. C2 100 PF T1 0.01 Cl 2N394 4 OUTPUTSIGNAL SIGNALINPUT 11K 2.2K R1 IKR3 0.1 C3 -10.1- C4 4_I+ (69, ON -OFF DC INPUT 1.5MA) 40 Fig. 2-3. Single -tuned 455 -kHz IF amplifier. 41 2.4-FET 455 -kHz IF AMPLIFIER biasingcircuits.be(typically, used scheme with 1000 thanstandard megohms the three IF in The high input It also permits impedance of field-effect a simpler controltransformersjunction -electrode -resistor-type intended FETs) allows arrangement required transistors for tube it toDC sourceis currentamplifier.obtainedby resistorthe drain conventionalentirely R1is 1.5 by from drain transistor. In this circuit, maemploying from the a 92N3823 -volt DC junction -currentthe voltage flow. The Fig. 2-4 shows an FET drop produced acrosssupply. DC gate bias -type FET, the IF IFtype transformers units (standard (T1 and T2,midget or miniature in size). respectively) are regular, tube DC INPUT (12V, 23MA) input and output - S1 R2 470ON-OFF .1 Q1 2N3823 DC INPUT SIGNAL R1 DC OUTPUT SIGNAL 42 Fig. 2-5. DC voltage amplifier. 43 curs,wiringtheadded transformers however, is toseparated the acircuit. simple are as well This is a Most setups of this circuit mountedmuch and as possible.connected If toIFneutralizing the capacitor (C1)shielded may and if input willand requireoutput no neutralizationminiature 50-pf compression - oscillation oc- correct be if transistors.thetemperaturevirtually individual zero has (maximumtransistor only a slight and 0.5 effectThe actual current gain obtained depends upon the resistance11 a(RL) for the of 2N2712)the upon operation of silicon upon the beta of and since endtypeof of2.5-DC Qi.trimmer, the T2 VOLTAGE secondary rigidly AMPLIFIERfor out -of -phase feedback to the gate increasesameoutput(thisexample,load 0-30 -current actiondevice, from ma an represents zerooutput input(Io) the tochange -current -current195 a of (Ii)0-30 gain decreasing as RL increases. current gain of 231), whereas for change thechange input of current0-130 oa must produces ma when RL equals 1 ohm Forthe an transistor,amplifycircuittrostatically DCis Qia voltagetrue (Typeoperated, voltage signals. 2N3823) amplifier.as seen by ByThe relatively simple circuit in Fig. Since it employs a whichfield-effect is the DC input signal-thiscontrast, a conventional 2-5 is designedessentially to elec- transistor.withinoutputlatter the action -current allowable represents level collector of 30 ma has beenThe circuit draws a maximum a current gain of pa154). when A RL equals 150 ohms (thispower dissipation of the 2N2712 chosen here to keep maximum inputtransistorOutputmade resistance higher, resistancedraws ifis inputdesired, is 470 -signal simply current, by In its resting state, the circuit determined by Ri (1 megohm) and may ohms. increasing drawsthe value 23 maof Ri.from the 12 - however slight. The be interest:ohms.frominputsupply; 4838 resistance DC When ohmsinitialpower RL when seen resting gainis 150 RL by iscurrentthe 1 ohmapplied is DC provided by thisohms, circuit for isexample, a matter the of input toonly 3395 0.5of ohms 30ua mamaximum. when from the 6The -volt DC input signal varies RL is 150 outputaccordinglyreducesvoltsupply DC signal-signal thissupply. voltage currentis from voltage(7.6-0.6)/1.5 A 0.6v DC andfrom may inputto the 237.6v. or masignal 4.66. to 8 Higherma beresistance obtained by of increasing R2, provided the the The open -circuit voltage gain varied from zero to 1.5v and increases the DC voltage gain and DC 2.7-DCproximately136 ow, CURRENT output 30 db). power AMPLIFIER is 135 mw, and power gain is 993 (ap- (POWER TYPE) power is replaceddesired,ceeded.maximum The bywith recommended meansinitial a potentiometer 0.6vof a output drain -tomay -sourceFor gain control, where required, conventional bucking circuit. of the same resistance, con- be suppressed to zero, if resistor Ri may bevoltage is not ex- employsdescribedhigher output an in HEP Fig. current 2302-6. PNP The than the 30TheFig. actual 2-7 currentshows gaina DC obtained amplifier circuit power highertransistor. level circuit shown here dependsma limit upon of the the beta circuit of which delivers nected2.6-DC in theCURRENT conventional AMPLIFIER manner. A conventional transistor, being(LOW-LEVEL TYPE) a The circuit currentin Fig. -actuated DCencounteredHowever,loadthe output individual device, forcurrent in the most with transistor low high the resistances -current and load(1 to (Io) to change from practically gain decreasing as RL increases. upon the resistance (RL) of the devices, we10 found ohms) the commonly zero (ac- device,whichtransistortheapplied2-6 transistoris provides ofapproaches DC a action commoninput (Q1)true signalto beta currentand produce timesthis amplification. current thea base -emitter direct -current amplifier.constitutes the base -input current of DC collector output current is amplified by inherentcurrent (where beta is The DCaccordingly supply;changedtually, 1 from ma)is 24.9. zeroto 250 to 10ma ma. as theThe DCThe circuit draws a maximum of resting current is only 1 ma. Higher corresponding current gain 250input ma current from the (Ii) 6 -volt was output current classtransistorthe44 current of service, (Q1, amplification Type since 2N2712) its staticof is especially the transistor). The siliconcollector current (Ico) is well adapted to this collectortransistor.levels -current may be obtained by replacing Qi with a higher Type 2N173, rating of 15 amperes. for example, has a maximum -powered 45 rn

2N2712 OUTPUT CURRENT (Io) ---1

DC OUTPUT SIGNAL LOAD DEVICE RL

DC INPUT SIGNAL Si ON -OFF

INPUT CURRENT DC INPUT (Ii) 1+ (6V. 30MA MAX)

= - -OPTIONAL GROUND

Fig. 2-6. DC current amplifier (low-level type).

HEP 230 4

INPUT DC OUTPUT SIGNAL LOAD CURRENT DEVICE (RL) (Ii)

OUTPUT DC INPUT SIGNAL CURRENT (Io) Si

ON -OFF

- DC INPUT (6V, 250MA MAX)

- - OPTIONAL GROUND

Fig. 2-7. DC current amplifier (powertype). (12V, 1.7MA) DC highconventionalequivalent),midget -value mica source functions video trimmer bypass amplifier as acapacitor, compensating C4 C3 (Elmenco components. The subminiature, capacitor. These are Type 427, or Si '/1 ON -OFF INPUT1 24-35 uH operationandor equivalent), also in because the RFis a spectrum,of 500-mfd the high electrolytic.all wiringBecause of the wide frequency -frequency upper limit of its response of this amplifier, (Sprague Type TE-106, R2 Ll 3000 stablemetalkept widely chassis.operation. separated These Video precautionsfrom adjacent amplifiers find application in in- are necessarywiring, to components, insure and must be rigid and 25Cl 2N3823 + C2 25 lowstruments, impedance2.9-DC SOURCE television, converter, FOLLOWER and already control noted forThe AC usefulness of the follower -type amplifier as a highsystems. -to - applications in SIGNAL I R1 C3 SIGNALOUTPUT withoutthisFigs. way, 1-6, the high1-7, extreme and-to -low1-9, voltage may resistance be division utilized conversion alsowhich for DC amay resistor be obtained circuit operation. In INPUT pearsinputeffectventionalwould inresistancetransistor, introduce. Fig. transistor, 2-10.) desired. Both and the the(The emitter source emitterThe follower source circuitfollower (Fig. 2-9) may be used, depending upon the amount of follower, usingusing a a field- con- ap- Fig. 2-8. Wideband (video) amplitier. acrosssourcevoltDCfield-effect inputDC this(output) supply. signal resistor,transistor. At resistoris thiszero), and point,In thisR3 the producesvoltagethecircuit flow draws mustof an drain initial be balanced quiescent state (i. e., when the employs a 2N3823 junction 7.5 ma from the 3 - current through voltage drop out by 2.8-WIDEBAND (VIDEO) AMPLIFIERThe amplifier circuit in Fig. 2-8 has a frequency response is 1 applied,outputadjustment signal with to ofthe zero. zero gate When -set of Q1rheostat a DCnegative, input R2 tosignal it reducereduces the the static subsequently is drain DC Employingmegohmextending1.7 ma fromat from a 1 2N3823 kHzthe 50 12 andHz -voltfield-effect toits 10 DCoutput MHz. supply. transistor, impedance Its inputAt 1 impedance kHz the maximum input -signal amplitude the circuit draws is 3000 ohms. before the and the A resistanceoutputtionatelycurrentDC input resistance and signalfrom may causes zeroofbe 1.5v1000increased in the the ohms. DC negative simply output If desired, direction.The however, input resistance the of the circuit is 1 by raising the value of Rl.signal to rise propor- megohm and the input Thecorrespondingonsetfortuneddown open highestof 2.5 inductoroutput -circuit db gain atmaximum -signal 50 Livoltage at Hzand 10 and peaktrimmerMHz. outputgain down clipping atBoth -signal 6capacitor1 dbkHz Ll at is and amplitudeis10 0.2v 10. C3MHz. C3 VoltageRMS,must are Initially, gain slug - screwdriverbeis adjusted 2v RMS. is bothpole,voltagewhile the single reducing gainDC supply -throwis 0.83. the and draintoggle the current switch. to ThisIn this circuit, S1 and S2 are the two produces a DC outputbucking signal battery, of 1.25v, Bl, to be switched 5.2 ma. The open -circuit arrangementsections of a allows double - 48adjusted.or equivalent), is employed as a peakingThe miniature 24-35-4 inductor, LI (J. W. coil, and the 55-300-pf Miller No. 4508, wirewoundwithoutsimultaneously, the other.rheostat. thus The eliminating zero the danger of -adjuster control, R2, is a 5000 -ohm one being on 49 0ai follower,follower2-10-DC (Fig.based EMITTER 2-9) upon a conventional FOLLOWER When the very high input resistance is not needed, a of thesimpler FET DC DC source emitter 0 0LUa) transistor2N2712Fig. 2-10 silicon showsis so tinytransistor. a DC (less emitter than 0.5 -followerBecause circuit the static collector current ua), the static voltage droptransistor, may be used. (Ico) of this silicon employing a cp:0U across emitter (output) resistor R2 is inconsequential; LL output,followertherefore, consequently, (Fig. the zero2-9) is-set is not zero circuit needed when required here.the input The by the signal is zero.initial DC signal FET source DC SUPPLY (6V, 2 MA MAX) + OLt - e-I1.4 A/V-41C4 jS1 ON -OFF I t. NW J CCC.1 LO 10KR1 Q1 2N2712 DC SIGNAL INPUT R2 500 DC SIGNAL OUTPUT 50 Fig. 2-10. DC emitter follower. 51 inpositive, the positive the DC direction. output signalA DC risesinput proportionately signalWhen of a1.5v DC produces inputfrom zerosignal a is applied, with the base of Q1 protective6maximumohmsAtDC -volt this output and 1.5DC -voltsignal-signalresistor. thesupply. outputpoint, of conditions, 0.8v.The the resistance 10,000Theinput openthe resistance -ohm circuit is-circuit 500 input drawsisohms. voltage greater resistor 2 Under ma gainthan (R1)from is80,000 these 0.53. isthe a Oscillators Chapter 3 onsimplicityrespectsThe extremely transistor found aside low infromDCoscillator transistorized input, the usual even smalldevices: is attractive microwatts, if need be, and size, light weight, and in two(1) importantIt will operate MHznowrestrictedfreedom(2) and can it higher.possesses be fromto depended low the frequencies, high overall the A number of oscillator circuits necessity of filamentupon power). to oscillate at frequencies efficiency (due intransistor part to its (in modern dress)are included here. While Originally up to 400 allthe capacitorstheythese text,circuits, do circuitscapacitances not areunless by rated illustrateany otherwise meansat various exhaust the are in mfd and resistances in 25 DCWV. Resistors are indicated on the diagram classes of oscillator possibilities. In each of 1/2 watt. ohms, and action, or in used.instances,beusedturers essential by are anythe indicated, authortocomponent correct and these Where particular performancethey orcomponents their of exact the circuit. equivalents from Inspecific all otherhaving manufac- the specifiedcomponents ratings are the ones actually seemmay to be components.capacitors,somewhatwithcurrent the are author's due given,resistors, to the these characteristics inductors, Where frequency, experimental model and they output -signal amplitude, andare the values which were obtained transformers,of andindividual other transistors, may varyoperating oscillator3.1-TRANSFORMER-TUNED employing a 2N107 AF OSCILLATORFig. 3-1 is the circuit of a sine -wave audio -frequency (PNP) common - 52 orohmbase equivalent). -to -2000circuit. -ohm Feedback For stepdown transformer, T1 oscillation, the transformeris supplied must by the miniature PNP transistor in a (Argonne AR -109, 10,000 - 53be red 10K blue 'VW)" T1 2000 0 C.T. Xelloi"gri black

2N107

UNUSED C.T.

Cl C2

1( Rl 1( 0.05 1K 0.1

Si" ON -OFF

SIGNAL OUTPUT

DC INPUTINPUT (1.5V, 1511A) r I

Fig. 3-1. Transformer -tuned AF oscillator(PNP).

2N3823

0 T1 blue black C3 Cx

wuiA I Cl a a i ( 20K a a 4000 1.0 R1 9K 0.02 aa o * red green I SA,ON-OFF SIGNAL OUTPUT R2 C2-100. +I 10K DC INPUT

OUTPUT CONTROL (6V, 0.5MA)

Fig. 3-2. Transformer -tunedAF oscillator (FET).

U, to capacitanceproximatelyofcapacitorpolarized1. the The transformer Closcillationcorrectly, of and1000 Cl; the toHz). as(ifinductance decreasefrequency indicated ClTo is increase 0.05 it, of byisraise themfd, determinedthe the low the color thefrequency, -impedancecapacitance. coding principally lower in winding Fig. the 3- frequency is ap- by At(Thevoltagepotentiometersignal 1.5v 2N107the amplitude may current maximumbe (R1) obtaineddrain of 0.65v is collector approximately by RMS. increasing ratings The 151.1a.1000 theareThis DC6v, -ohm 10circuitsupply wirewound voltage.delivers a maximum is the output control. Higher output open -circuit output - ma, 50 mw.) 3.2-TRANSFORMER-TUNED AF OSCILLATORIn a transformer (FET) -feedback oscillator, the high input im- srna) - 0 windingwaveformloadingpedance of of theandthe the transformer stability.tuned field-effect circuit, It to also be transistor and usedallows this as atheresults offerstuned high LC invirtually -impedance improvedtank in theno ...4(og0)01:1 CU -0cu 2N3823transistor FET input in circuit.the common -source Theconnection. sine -wave Feedback oscillator circuit in Fig. 3-2 employs a C \O CN/CN minedARratiobetween -105,by principallyminiature the or drain equivalent). 20,000 -output by capacitor -to andThe -400 gate oscillation -ohmCl -input and transformer the is frequency suppliedinductance T1 in is ofdeter- the (Argonne step-up z("N feedbacktransformerthefrequency,high frequencycapacitance). -impedance (follow lower must is thewinding approximatelythe Inbe color capacitance orderpolarized codingof thefor transformer theshown correctly 150of circuit C1; Hz).in toFig. for(iftodecreaseTo 3-2). Cl oscillate, regenerativeincrease is 0.02 it, raisemfd, the potentiometersignal amplitude (R2) ofis the0.6v output RMS. control. The 10,000The The oscillator current-ohm wirewound drain delivers is a maximum open -circuit output - v-1 C",)M1--- outputcurrent0.5 ma from-signal drain the amplitudeincreases 6 -volt DC to supply. lvapproximately RMS. With a 12 -volt 0.75 DC ma supply and the the C)03L-Li I <--)I-1ZL. CV (Z) 4. notresistorample significantly degeneration (R1) unbypassed, increased which and resultsby the bypassing output fromThe leavingsignal Rl. waveform If amplitude itthe becomes source of isthe signal is greatly improved by the V)rI= 561-presentnecessary or 2-mfd in ato capacitordevice isolate to potentiometer which(CX) may the oscillatorbe R2inserted from delivers ina DCthe outputcomponentits signal, line. a 57 3.3-HARTLEY-TYPE AF OSCILLATOR 0 Hartleytuned,coilemploy for sine -typepositive a -wave, transformer circuit, feedback. AF inoscillator whichwith A one the is shownThe two oscillators described second typewinding of transformer serving as a ticklertuningpreviously and (Figs.feedback 3-1, func- 3-2) in Fig. 3-3. This is a - U) couplingothertions arewinding coil. accomplished of the transformer by a In this circuit, miniature single center -tapped winding; thetransformer T1 is a 500 -ohm then serves as an output - U) \ Thecollectorwindingequivalent). (centeroscillation serves-output -tapped) The as coil. theupper -to base -30 half -ohm of the unit Capacitor C3 tunes the entire -input coil and the lower half as the (Argonnecenter AR -117, -tapped primary primary. or D. I L.) Toing.capacitor increase If C3 istheC3 0.02 andfrequency, mfd, the theinductance of frequency frequency is approximately 2000 Hz. is determined the entire primary wind- principally by o- rCs.1 -I InM 0 (followtodecrease oscillate, the it, color increase the codingtransformer the shown capacitance. In orderdecrease for the the circuit capacitance of in Fig. 3-3).must be polarized Capacitor C2 is not correctly C3; to c.r) drainopenvoltagepart -circuitis of 2 ma thefrom fromoutput tuned the the -signalbasecircuit, 6 -volt of amplitude thebutDC transistor. of 0.8v serves to block the collectorsupply. DC The circuit delivers RMS. The current an -We-- ri anoteddesigners, 33.4-PHASE-SHIFT -legged for its is RC excellenttuned network entirely RCsine AUDIO by resistorsThe phase -shift oscillator, familiar to resembling-wave signal a high-pass output. In RCthis filter OSCILLATOR and capacitors and is all electronic circuit, CDCs./ Cs1 andsupplies input the to producenecessary oscillation 180 Fig. 3-4 shows a phase -shift oscillator -degree phase shift between in a single amplifier stage. output O C -)O\ c=:. O threecuits)2N2712(connected 10,000 consists silicon -ohm betweenof transistor.three resistors 0.002-mfdthe collector (R1, R2, the series totalHere, of the phase -shift capacitors-output (C1, and C2, base C3) -input and cir- circuit employing a networkR3, and C-) thedegreestypethe needed of base network,of -ground180phase shift;each internal ofthus, the the three degrees. resistance of the transistor). In three legs in cascade identical legs supplies 60 supply this 58 2000the phase Hz. (Some -shift network in With the resistance and adjustment of R3 is necessary according to Fig. 3-4, the oscillation frequencycapacitance values specified for the59 is 0.02 C2 red blue' T1 , greenSIGNAL 0_ brown a black I11 OUTPUT (r)1-4C.D-J Cl 0.1 --01(r -I tc. Ln o R1 L.) 0q0 0-1 0.37M 2N 2712 VD LLCD - + red C1 0_ OC PC black ,00, UCV CD f-- Fig. 3-5. Light -operated AF oscillator. zCNA here,frequency.)characteristics the oscillation For of any the frequency phase transistor -shift f is in networkequal of the use and this will affect approximately to 106/ type shown threefrequency(20 capacitances, RC), may where be changedfall is three in Hz, by R simultaneously in ohms, and C in resistances, or both, by the same changing all mfd. The OC LS) plitudeamount. of Increasing 3v RMS. TheR or current C decreases drain is 0.5The ma circuitfrom the delivers an open -circuit output -signal am- f, and vice versa. 12 -volt IP.1k 0 0 0 r -I DC3.5-LIGHT-POWERED supply. AF OSCILLATOR V)e -I O 7U - tD operate at a very low DC collector voltageThe make high efficiency of the transistor and its ability topossible the JI-1 thegeneratorsoperation60 circuit of ofinclude oscillators a simple photocells Hartley from low and -voltage thermopiles. DC -type, sine -wave audio oscillator generators. Such Fig. 3-5 shows 61 equivalent:siliconwhich receives photocell, Output its DCPCis 0.55v (Internationaloperating DC in power bright Rectifier from sunlight). a self Type S1M, or -generatingExcept for oscillationequivalent)healthe use with of thethefrequency is Hartleyaphotocell 500 -ohm oscillator as (center the DC shown -tapped) earlierThe -to -30miniature in -ohm unit. transformer, The T1 is determined principally source, this circuit is iden- (Argonne AR -117, Fig. 3-3. by or theapproximatelywindingcapacitanceformercapacitance. of must the C2 transformer. 2000 beIn and polarizedorder Hz. the To forinductance If increasethe C2 circuitis 0.02 the of mfd,to frequency,the oscillate, entirethecapacitance decrease the trans- of C2; correctlyto (follow the color coding decrease it, increase frequency is primary the photocell).ofcorrectly,(correctshown the transistor inso color Fig.that its3-5). codingand positive theThe is photocell alsoDC outputshown also isThe in applied must circuit to thedelivers base an negative outputopen to -circuitthe emitter output -signal am- Fig. be polarized3-5 for the event,Suchillumination.abrightplitude silicon a the battery ofoscillator sun 0.09vProportionately consists battery RMSoutput of is when severalsubstituted-signal higher the cellsamplitude photocell forwired the is in issimpleproportional series.illuminated cell, toPC. sunlight and somewhat output may be obtainedless if under artificial In any by radio3.6-SELF-EXCITEDthe -frequencylight intensity. oscillator (See RF with Fig.OSCILLATOR 3-14.)a continuouslyFig. 3-6-tuned shows the circuit of a self-excited, Hartley -type range of tuned308,2023,adjustment350-pf500 kHz or circuit.or variableequivalent). toequivalent) 4 of MHz. the capacitor slug TuningRadio and of padder(C4), -frequency oscillatoris accomplished the capacitor exact coilchoke range Ti byC3 Ll (J. means is(Elmencobeing W. not Miller part ofpreset ofType No. theby midget fromoutputtransistorminals,correctly the -signal 6 given -volt both amplitude DCin for Fig. supply. oscillation 3-6). of 0.65v The and circuit RMS. impedance deliversCurrentThe oscillator matchdrainan is with coil2 ma the(transformer), Ti, must be (follow the manufacturer's numbering of ter- open -circuit polarized 62receiver.applications, Its operatingincluding usefrequency as the oscillatorThis stage circuit, of witha superhet its 0.5 -too -MHz tuning may easily be changed by range, has many 63 substituting for T1 a coil having an inductance rating suitable books.mayfor3.7-CONVENTIONAL the be desired wound frequency.according CRYSTAL toSuch instructions coils, OSCILLATOR for found use with in radio tuning hand- C4, cuitserveskilldeviceCl, andoscillation.oscillates onlybe necessitates high to as keepenough Whensoon RF thatas the that energyswitch the circuit it impedancewill Siout isisnot of closed.oscillating theoverloadCapacitive ofDC the supply. theatexternal theoutputcircuit The loadcoupling andcir- is provided through capacitor crystal quartzcircuitoscillatorvacuum crystalemploying circuit-tube (XTAL) version. which a 2N3823 is has Fig. operated theFET. 3-7 same shows Inin this theconfigurationThe such FETarrangement, field-effect a gate/ground conventional as the transistor makes possible a crystal oscillationofpoint,frequency, (thethe the crystal.author's open willit draws Therefore, -circuit taketest 2.3 placewas RFma made if atoutputfrom you the atthebasichave -signal 7 12 MHz). afrequency -volt harmonic amplitudeThe DC Pierce supply.of is the 6.2v circuit At RMS that oscillates at the fundamental -type crystal, frequency crystal, favorablewouldingroundinput the circuit drain/outputbe circuit placed positions in ofthe ina sametube, thecircuit for plate/output waybothand of thethat crystalthe tuned itFET wouldcircuit and tankin Thethebe tank.of (L1C3) placed a samevalue tube. isway inofThese operatedthe Ll that grid/is are chosenit to tune with variable capacitor oscillatornot3.9-MULTI-FREQUENCY at the demandslabeled (harmonic) a very active CRYSTAL frequency. crystal.The OSCILLATOR utilityAlso, theof aPierce may be extended by temporarilyansimplyfoundmayC3 RF to be the vacuuminofused, radiotuningcrystal to or the -tubehandbooks.a C3 coil frequency.signal for (or may maximum transistorized)output be Oscillator woundEither terminals. RF accordinga output,commercial adjustmentvoltmeter Alternatively, as to indicated instructions connected inductorconsists a by0- plicationstability.signalsincluding at ofIfseverala crystalaLC Pierce tuned frequencies -switching oscillator tanks is to section. avoided.circuit be generated, isTheFig. employed, capability 3-9 all shows with the enables crystal acom- circuit adapted for mayCapacitancepositive5 DC be milliammeter used DC outputinputonly when linecoupling may and the be C3external(through inserted tuned loadC4) fortemporarily isdipdevice shown of the has here into meter. a suf- andthe 0.001 from2-instances,norficiently or load 3the -turn high the latter.low coilcircuit impedance -impedance wound so heavily around that coupling it asthewill to bottom cannot kill bedetune oscillation. achievedof Ll the and L1C3 throughinsulated In other tank a XTAL hIL RFC1 2.5 MH 1.1v123.8-PIERCE -volt RMS DC (the supply. author'sCRYSTAL The test open OSCILLATORwas -circuit made output at 7 AtMHz). -signal the crystal amplitude frequency, is the circuit draws 1.7 ma from the 2N3823 Si -OFF circuitthat it requires employing no tuning a 2N3823 adjustments. field-effect Fig.An 3-8advantagetransistor. shows a of InPierce thethis Pierce crystal oscillator circuit is RI ION (12V, 2.3MA) DC INPUT RFgrid/inputwaythearrangement, drain/outputchoke that a sections(RFC1)crystal the and quartz is of doesgate/input operated the crystal notequivalent ordinarily sectionsbetweeen (XTAL) tube of tune theisthecircuit. operated plate/outputFET the Thecircuit,in thebetween 2.5-mh same andbut Fig. 3-8. Pierce crystal oscillator. 64 LL 65 / crystal switching. Except for the addition of several crystals Qa_JF- a_ gang,Pierceand the nonshorting,oscillator switch (S1), described rotary the circuit previously.selector is identicalswitch Switch having with Si is theaas single manybasic - -LO dependingcrystalspositions are as uponshown there frequency here, are crystalsany numberand (Xl,especially may X2, Thebe etc.). used.upon RF Whileoutput crystal five-signal ac- amplitude will vary somewhat, LO U- fromlikewisetivity, the but will 12 it will-voltvary be somewhat,DC on supply. the order but See willof Section 6.2v be on RMS. the3.8 order forCurrent additional of 2.3 drain ma LL. pointers3.10-SELF-EXCITED on the Pierce oscillator. 100 -kHz OSCILLATOR ---4 0 00 0-0 U)U0 oscillator suitable for many applications whichFig. 3-10 do not is demandthe schematic of a self-excited 100 -kHz 03 .(43Us - capacitorColpittsthe(L1 high -C3 oscillatorstability-C4). (C3 -C4) of circuit, tuninga crystal whichof oscillator.the frequencyis characterized This -determining is a version by the ofsplit tank the - z(NI 0a)a)U Milleradjusting No. the 6313, tuning or slugequivalent) of the 0.5 while to 5-mh zeroThe inductor, beating oscillator againstLl frequency(J. W. a may be set exactly to 100 kHz by :«7 draincircuitwireisstandard provided woundis 1.25RF -frequency byoutput matightly coil from L2 -signalaround thestation which 22.5 amplitudeLl. WWVconsists-volt This DC signal.oscillator of supply. of 15 lv turns RF RMS. delivers output of No. Its coupling an22current DCC open - U- shouldspotting3.11-CRYSTAL-TYPE be or used. frequency Fig. 3-11 -standard 100 is the -kHz circuit OSCILLATOR oscillator, forWhen such crystal a maximum crystal control -type stability is desired in a frequency - 0-1 F ;\<' 3-7.groundHere,100 -kHz circuit,the 100oscillator as-kHz in theemployingquartz basic (XTAL) crystal a 2N3819 is oscillator operated field-effect shownin the transistor.FET in Fig. gate/ c4 dicatedaccomplishedmica(J. W.capacitor by Miller an RF C3by No. vacuumtuningand 6318, the Li slugor-tube for equivalent). -tuned maximum(or transistorized)The 0.3 resonanttoCircuit RF3-mh output, adjustmentinductor, tankvoltmeter as is in-composedLl is of 0.002-mfd silvered 66 E mayCapacitiveconnected be used temporarilyoutput only coupling when the (through external C4) load is deviceshown herehas suf-and to the signal output terminals. 67 o. 00

Q1

2N394 C3 0.0025 a LIa L2 SIGNAL OUTPUT

C4I0.0025 RFC1 a020 MH C5 a R2 0.01 C1 7. 0.01

11M

S1;\ON -OFF R1 51K

C2 R3 9.1Ic 0.005 DC INPUT (22.5V, 1.25MA)

Fig. 3-10. Self-excited100 -kHz oscillator.

C4

100 PF I Lel 2N3819 (71 C3 7.0.0029 0.3-3MH

SIGNAL OUTPUT MXTAL R1 1M 9 1 S1 R2 C2 ON -OFF 1.8K 0.01's 0.01

DC INPUT (6V, 1MA)

Fig. 3-11. Crystal -type 100 -kHz oscillator. rn 4.0 CD

HEAT SINK 4

Q1 2N301 Ti

C1 4

C2 0.1 UNUSED C.T. OUTPUT se NVR2 1K (24 Si% 11 R1 ON OFF 100 R3 4 (2W) 1K (5W) R4 DC INPUT (12V, 180MA) 100

(216I)

Fig. 3-12. Power AF oscillator.

C5

1

T1 3-12PF BEAT -NOTE ADJUST

C4 I 2N169A 50 Pc

0.002 I SIGNAL OUTPUT C3 R3 0

3.9K Si ON -OFF __C2 R1 1.81< 0.005 Cl R2 2K 0.005 DC INPUT (6V, 2MA)

Fig. 3-13. Beat -frequency oscillator (BFO). andficiently severely high reduceimpedance its that it will not overload output. the oscillator beslug, preset a convenience through a thatcombination permits the of audible T1 and beatC4 adjustments.note range to 3.I2-AFsupply.signal POWERamplitude OSCILLATOR of 5v RMS and draws 1At 100 kHz this ocillator delivers an open -circuitma from output the - 6 -volt DC bodythetouchedadjust(The pitchreceiver; -capacitance theusual again.of T1 the procedurethen, slug Asbeat C4 with foreffects,note is zerois C4tunedwill to setfollowbeat.tune increase.) toward to -in Theits the amaximum minimumsignal slugTorotor prevent then "onand capacitance, capacitance,the needstator deleterious nose" not con- withbe ofbothpowerdelivers Cl asand transistor 1/2a C2tuned watt in ofseries, tankin a Colpittsand the inductance circuit. TransformerTheFig. oscillation3-12 shows Ti frequency the circuit is of power to a 200 -ohm load. It employs a 2N301 output coupler. governed by the capacitance an AF oscillatorof the which 200 -ohm primary serves lownections 3.14-MICROPOWERDC voltage shown and for current, C4 in AF Fig. aOSCILLATOR feature 3-13. thatTransistors has made arepossible noted for their ability to operate from very frequencybyDCtappedtransformerwinding adjusting (Chicago-Stancor secondary, mayof transformer hasR3.be varieda 200and from-ohmitsTi, primary and the Type TA -58, primaryapproximately and 200 -ohm 400 center Hz to - 3 kHz settingwinding of rheostat can carry R3. 200 The ma or equivalent). The necessarilyoutputsuchphotocell,the an powering oscillator-signal or linearly) any amplitudeof is similar usefula totransistor the asDC applied isa DCsupply. oscillator -to DC -AC In voltage. some transducer,from applications,the feeble since itsDC of a thermopile, makeshift proportional (though not battery, low -output minimizetransistortubularwirewound heating.unit must rheostat. (do benot operated useCapacitor an with Cl isThisAll oscillator fixed resistors delivers are a full 2 -watt size electrolytic capacitor here). The 1/2 watt to a 200 -ohm loada heat and sink, as shown,a 4-mfd to metalized paper and R3 is a 5 -watt maydraws3.13-BEAT-FREQUENCY be 180 obtained ma from by the using 12 -volt OSCILLATORhigher DC -powered ( BFO transistors. ) supply. Higher power output 2N190 shielded,Thissuperhetthrough is 455 aC5 receiver,Hartley -kHzto the BFO IF -typewill or coil, secondadapt circuit T1 the (J.-detector receiverW. Miller sectionThe for 455 -kHz oscillator shown in employing a commercial, Fig. 3-13, when coupled No.CW 912-05,reception. or of a straight Q1 blue T1 black 1.0C2 frequenciesequivalent). Theby substituting circuit may anbe The circuit is conventional in all appropriateadapted to other BFO intermediate coil. respects. IF energy is red III400 green S1 ON -OFF SIGNAL OUTPUT 1 onvariableusuallyadjustedequivalent.coupled (and insulatedneedscapacitor trimmer out The to of befrom)(C4), trimmercapacitorthe adjusted oscillator the front C5 (Centralab by on the other hand,may beshould mounted be mounted internally, since it only once. The 50-pf midgetpanel of the receiver, as itmeans of screwdriver - Type 822-FZ, or DC INPUT (0.1V, 10MATYPICAL) dividualpermits72 manualear. Current adjustment drain is of the beatThe note BFO unit (Ti), has a 2 ma from thescrewdriver 6 -volt DC supply.-adjusted tuning to suit the in- Fig. 3-14. Micropower AF oscillator. 73 0 0 tocircuit(representing the forDC operation input a DC terminals, from input a power low the DC of current supply.1 microwatt),Fig. 3-14With drain shows 0.1vand theapplied a opensine -wave- audio -frequency oscillator is 10 pa equivalent)20,000circuitcurrent output ohmsoutputis very serving-to -signal -signallittle -400 more ohmsamplitudeboth amplitude than astransformer, the the is is feedback 1.7original 10 my myT1This RMS. (ArgonneRMS.10 coupler is pa, aAt transformerbut 0.2v ARand the DC,-105, asopen the the or-feedback - oscillator with a miniature C) decreasefrequencyimpedancecipallytuned tank. Cl;by iscapacitancewindingfor Theapproximately lower oscillation of frequencies, the Cl transformer. and 400 frequency the Hz. increaseinductance For If is Clhigher determined isCl. 0.005 ofThefrequencies, the mfd,trans- high prin- the - .0 wi 00 "C (19 f cu former3.15-CARRIER-OPERATEDback; followmust bethe polarized color coding correctly shown AF OSCILLATOR in for Fig. regenerative 3-14. feed- z0' CV LC) section may be adapted to operate fromThe the micropower RF carrier ofoscillator a described in the foregoing C-.) (- placedinsulatedamountbatteryless,radio close oftransmitter. hookup RF to, CW energy but wire, monitor. insulated In is closewound thispicked way, from, up it by 2the canor coil transmitter3 The beinches Li usedcarrier (2 orin as diameter)tank3 -operated aturns simple, coil. of circuit appears in Fig. 3-15. A small -J'-44 Ocp resistorThecoaxialRF energy resulting cable(R1). is conductedto BypassDC the voltage oscillator, capacitor by meansappears where Cl of andacross ait lengthis RF rectified thechoke of 100 twisted byRFC1 -ohm diode pair filterload Di. or crC- DCthe radio then -frequencyis applied tocomponent the oscillator. from the DCIn all output. other The respects, clean the oscillator circuit is identical with 1-4ce CJ voltagethefrequency outputone (and,described is-signal approximately by backamplitude in Sectionreference, 400 is proportional Hz3.14. proportional when The C2 togenerated is the 0.005 to applied the mfd carrieraudio andDC 1-4V) C) 11"-AAAr-- Zg'.4Ln cathodevoltageamplitude). atpositioning the Diode, collector D1,shown of must the in transistorbeFig. polarized 3-15). (follow for athe negative anode andDC r -I 0 0 signalpower in transmitter, high -impedance this headphonesoscillator produces connectedEven when ato substantial the it signal is operated - from the RF carrier of a low - 1174 -1 A A ri I AFvolume,output amplifier. terminals. the output ofFor the other oscillator applications may be fed requiring into a suitable more 75 ov DC INPUT (22.5V,5.6MA)

S1 ON -OFF

Fig. 3-16. Pulse-generating oscillator.

490 R1

2N2646

C2

C1.,.0.1 0.1 A R3 17 0 SIGNAL OUTPUT 1

DC INPUT (22.5V, 6MA)

S1 ON -OFF

Fig. 3-17. .

1 39K R2P90

C2 IF 2N2646 0.1

C1--0.1 3 3

SIGNAL OUTPUT 1

CO

DC INPUT (6V, 2MA) Si,' ON -OFF

Fig. 3-18. .

tRI R3 10K 100

C2 c,SIGNAL 2N2646 0.1 OUTPUT 1 Ifl-f1J--- - C1

0.02 C3 SIGNAL 0.1 OUTPUT 2

WAVEFORM ADJUST R4 2 100

R2 10K I ()COMMON

C4

5 PF

4.5 -MHz L 1 XTAL 0.4 c) C3 100 PF c) 7-14u H c)

el tR 1M H SIGNAL OUTPUT RF 0

R11330 (7.5V, 14MA) o o - + DC INPUT R2 220 C1"0.005 R3 4 820 C5 0.01 C2 0.005 27K

Fig. 3-19. TV sound -channel marker oscillator. 3.16-PULSE-GENERATING OSCILLATOREmploying a 2N2646 unijunction transistor, the oscillator 0 II teristics.capacitancecorrectly,circuit inWithuses repetition Fig. C1, simpleR1 3-16 andequal delivers rate) RCto to some are determined extent theIn this arrangement, the tuning. sharp -pointed,pulse positive width pulses. and frequency The (more transistorby resistance charac- R1, becomesmaintainedrepetition 160 rate at 39K is and Cl is 1600 pps (pulses 39,000 ohms and Cl to 0.1 mfd, the increased to 1 mfd, the per second). If R1 is rate (NJ CD Li heightof soonresistorvaryingthe 2N2646of exceeding 9v valueCl. peak. emitter.)(It cannot Currentmaythe safe alsoThe bedrain be isvaried 5.6 pps. Thus, the repetition rate voltage- and current -handlingreduced limits indiscriminatelyoutput pulse has an ma fromby varying the 22.5 R1,-volt but DC that may be varied by open -circuit without slightlyployingsupply.3.17-RELAXATION acurved, 2N2646 positive unijunction OSCILLATOR -going, transistor. sawtoothFig. 3-17 is a schematic of a relaxation The output signal is wave, as shown oscillator em- a frequencyincreased0.1characteristics.capacitanceopposite mfd, themay to the frequency1 mfd,be signalWith Cl, varied the and the-output is value byto some terminals of extent inThe sawtooth frequency is frequency becomes1600 Hz. 160 If R1Hz. is Thus, held atthe 39K and varyingdetermined Cl. (It may by resistancealso beR1 at 39,000 ohms and Cl at Fig. 3-17. by the transistor Cl is R1, voltage-andreducedvaried by indiscriminately varying current R1,-handling but without that limits ofThe the output saw tooth has resistorsoon value exceeding cannot the be safe 2N2646 emitter.) + 1 0 O. 1.1: 0 peak.3.18-MU Current LTIVIBR drain is ATOR 6 ma from the 22.5The -volt unijunction-transistor an open -circuit amplitude of 0.42v DC supply. IJ - - "0 negativeresemblesthe3-18 preceding is -goingsimilar that section. signal toof the a conventional atrelaxation Its the Two output signals are quasi square -waveprovided, output, however, as shown in Fig. 3-18-aoscillator circuitoscillator shown circuit in describedmultivibrator. in Fig. a 2circuit mapositive80 from peak -goingthe amplitude 6 -volt one DCat of the each signal supply. signal signal-output is 10.56v. terminal-output Current 2and terminal. drain is The open - 110 capacitancefrequency.adjustmentsignalaid of-output an oscilloscopeThe Cl,has 2) andfrequencyforonly minimum to negligible some is determinedtilt The 10,000 -ohm rheostat connected to either (R2) must be of theextent top ofeffect bythe the on the oscillation byadjusted resistancesignal (with -output R1, the 1 or wave. Thistransistor oscillatora gaphalfemployed,positive,bridge -cycles,between rectifieris pulsatingdead. sincewhereas adjacent (RECT) it DC providessimpler halfsupply. that half-cycles, anconverts Full -waveunbroken -wave a rectification thegap AC train rectificationin which of the supply to a results in positive is maycharacteristics. 3.19-TVbe used toSOUND mark If Clthe -CHANNEL is 4.5 0.02 -MHz soundFig. 3-19 shows the circuit of mfd, the frequency is 2600MARKER Hz. OSCILLATOR a crystal oscillator which testrequirement,frequencycrystal oscillator (XTAL) astheof the the oscillator and power AC is 100 supply.supply. may -percent beWhile Because operated modulatedThe of oscillatorfrom its atlow output signal has the a crystal oscillator is frequency of the twice thean audio power indicatedW.frequencysuchaligning Miller marker. by No.by a a TVadjusting 4406,VT This receiver (or oscillator the withslug -tuned or equivalent)transistorized) for maximum RF voltmeter is fix -tuned to thea sweep4.5 -MHz generator that has 7-14 ph inductor,channel Ll (J. when visually output,connected as crystal no Llgermanium typeselfshownis chosen -modulated meter in diodesFig.to rectifier. resonate 3-20, inconnected the a withIt self-excitedsame also asmightmanner. shown RFconsist in oscillatorThe Fig. ofrectifier 3-20. four also Inductorsilicon (RECT) may be a miniature, 10 -ma bridge - may be or theThiswhich base,temporarily arrangement is connectedwith to the signalbase Resistors R2 and R4 in respect to the emitter bias and places an optimum DC -output terminals. seriescircuit form of the a voltage 2N169A divider operating bias on collector bias. transistor. to openDC200frequency. -circuit output-Hz output RFof the outputof anrectifier audio -signal oscillator(Edc average in (AC -carrierIn an experimental setup of the circuit tuning capacitor C2 at the crystal Fig. 3-20) was 2.8v and the supply, 6v RMS), the operated from the 14ClMillergrounded.The mato C4, from No.DC inclusive, 4652, thesupply 7.5 or -volt floats DC RFC1 is a 1-mh miniature areequivalent). silvered -mica For best types. stability, The and the voltage -divider radio -frequency choke circuit draws capacitorstap -off is (J. W. conventionalimpedancecapacitive2.3vthe RMS. The outputcoupling, link signal -coupling coupling is ifmodulated desired, coil (through wound 100 around C3) power supply frequency). may be obtained withWhile apercent at 400 Hz (twice high is-impedance, shown,the bottomlowamplitude - end was plicationssignal3.20-SELF-MODULATED amplituderequire an is 4.5v RMS. RF A number of communications, control, and testamplitude -modulated RF oscillator.supply, and the open -circuit OSCILLATOR output - ap- of Ll. supplyAC.simplyamplitudemodulatorSuch The frequency.oscillators RFby modulationchangingstage (at least the oscillator output then becomes modulated usually are complicated may be obtained without complicationsone additional transistor) power supply from DC to by a separate AF at the power - ; however, theforwardwithouttransistor AC supply, drivingconduction. circuit, the theresult however, transistorThe When this type of self beingremedy a DC ripple is to rectifyvoltage (but not-modulationthe full is AC employed cycle(sometimes destructively) into cannot be used (always of with afilter) 82beenoscillatorthe same adapted employingpolarity). to self aFig. 2N3819 3-20-modulation field-effectshows the circuittransistor by means of of a full -wave which ahas crystal 83 Control & Alarm Devices Chapter 4 andrelativelyonlytransistorresponse,Its high remote one sensitivityactive to simpleand control.use generallyelement in equipmentcontrol The must 21 lowdevices circuits be to power used.obtain and described Thus, alarmrequirements reliable it devices isin possible nearthis in chaptersuitcontrol which with the (both DC and AC), wide frequency systems.oscillatorsbewillare used combinedrepresentative suggest as theyfrom other with are Chapter applications.of amplifiersshown; various 3 tobut, classes producefrom They as building Chaptersofare moreelectronic intended blocks, complex 1 and primarilycontrol they2 controland/or may and to specificresistorsresistancesdiagramtually usedatmanufactures or one-halfin inby ohms. the watt.author Capacitors are Where andindicated, they areparticular (orrated they theirIn ateachcomponents are 25exact theofDCWV theseequivalents, ones from circuits,and ac- unless otherwise indicated on the the text, capacitances are in mfd and whereexperimentalthesephase,specifiedthe circuit. available) are signal electricalthe In modelallvaluesamplitude, seem other ratings to andthat instances,be they voltages,wereessential may may obtainedbe any varyused.toand component correct currentssomewhat Wherewith operation the frequency,havingare author'swith given, of thein- milliampereDCAdividual transistor relay4.1-SENSITIVE transistors will operated-type perform relay and DCas a thusacircuit varietyRELAY DI mayamplifier components. of (NPN)be switching operated in conjunction applications. from a control with Aa 84cuitsmaysignal beof of thisoperated only type a feware on shownamicroamperes, few milliamperes.in Figs. 4-1 or toan 4-4. Sensitiveampere -type relay relay cir- 85 coo

Q1

2N190

RY

1000 Q c- 1MA c-j DC CONTROL -SIGNAL INPUT 0+ t TO CONTROLLED CIRCUIT (18.7 wA, 0.15V) 0 ON-OFFI 0 DC SUPPLY (6V, 1MA)

Fig. 4-2. Sensitive DCrelay (PNP).

Q1 R4 MHZERO SET 2N3823 1K*

RY

1000 cc

) 1MA -o TO CONTROLLED DC CONTROL -SIGNAL CIRCUIT INPUT + R1 10M (0.09 1A, 0.9V)

R2 R3 Vs". AAA, 500 500

0 o DC SUPPLY ON -OFF Fig. 4-3. Sensitive DC relay (FET). (6V, 9 MA) Fig. 4-1 shows a relay circuit employing a 2N2712 NPN therelayatsilicon (Sigma0.57v circuit (i. transistor. e.,is 5F, is amplifiedto 45.6K. or 1 equivalent).ma The at sufficiently 1v).relay The A(RY) DC equivalent by controlis the a 1000Due transistor signal input to -ohm, the ofresistance veryto only1 close -ma high 12.5 unitthe collectorof u a resistance of the 2N2712, the DCbalancingzero4.2-SENSITIVE supply -signal circuit is current 1 ma. is DCrequired.through RELAY the Maximum relay (PNP) is insignificant, drain from the hence 6 -volt no equivalent).negativePNPdescribed, germanium collector except A DC that controltransistor.voltage the signalcircuit and The negativeof in 18.7 chiefFig. Theua 4-2control differences at relay employs0.15v circuitvoltage.(RY) is amplified a are is2N190shown a the1000 in -ohm,Fig. 4-2 1 is-ma similar unit (Sigmato the one 5F, just or DCbalancingsufficientlythroughlv). supply The circuit equivalentthe isby 1 relay,the ma. is transistor required. inputit is too resistance to Maximum small close totheof disturb thedrainrelayWhile circuit (i.from thea e., measurableis latter,theto 8.02K. 1 6 ma -volt so at no zero -signal collector current flows circuit4.3-SENSITIVE in Fig. 4-3 DCoffers RELAY 10 megohms (FET)Employing input resistance. a 2N3823 If field-effect transistor, the relay closeofohm, increasingdesired,0.09 1the -mau relaya attheunit the0.9v (i. input(Sigma valuee., is toamplified resistance 1of 5F, ma resistor or at equivalent). lv).sufficiently mayR1.The beThe relaymadeA by DC zerothe (RY) controlstill transistor -signal higheris asignal 1000 drain to by - current of the transistor is higher balancingforwhichmeansbalancedthan relay that isof setdropout) requiredtheout operation for 1000of zerothe under to-ohm, relayisvoltageclose made zero wirewound, coil.the across possiblecontrol relay, Balance the hencesignal zeroby relay is a accomplished -setfour mustconditions.. coil rheostat, -arm be(or initially simplybridge TheR4, by 88 maresistanceconsisting from the of of 6the resistors -volt transistor. DC R2, supply. TheR3, andcircuit R4 draws and the a maximum internal drain of 9 89 4.4-HEAVY-DUTY DC RELAY 4.5-ALL-SOLID-STATE DC RELAY Fig.tromechanicalDC relays,4-4 shows the arelaysame circuit maycombination used be to used sensitize with of DC a 6While -volt, the32 -ohmthree preceding circuits employ sensitive, 1 -ma,higher -currentamplifier relay. plus elec- relay internalallthetromechanical -solid-state controlled collector relay relaycircuit resistancecircuit may or used. device)be of dispensedSuch is a lowcircuitWhen with with has anentirely respect the external obvious and to loadthe an resistance (i. e., the resistance of the transistor, the elec- 2800).relaydevice,control(Potter (this a 2N301signal represents& Brumfield topower the 187.5a transistor power Type KA5DY,amplification amplifiesThe or the circuit 4of better draws a maximum of 200 -ma, 6v level required to close the equivalent).ma from the In 12 this -volt -ma, 0.1v DC than amplificationcircuitdeviceadvantage of(RL) a of 2N301 isfreedom obtained connected power from with transistor. directly moving an arrangement in parts.The theFig. amount collector 4-5 ofshows of this currentoutput asort relay circuit of this kind. Here, the load transientsconnectedtobalancingmeasurable,DC the supply. DC generated circuit control1N547 Althoughit is -signalsilicon required.by the the sourcediode The (Dl) isinput 25 ohms.resistance is too low to disturb the zero -signal collector currentrelay is -coil inductance, which suppresses kickback relay. Hence, no The reverse - presented currentrequiredtheplificationFordepends DCexample, iscontrol upon output1.5 (for amperes thewhen the-signal load load 2N301) RL current).for resistance,input is the 30approaches current2N301. ohms The varying maximumneed orHigher 50less, beinversely(which currenttheonly DC current means1/50 collectorwithoperation of am-thatRL. the desiredchosenothermight heavy damageto current (1) -current handle theamplification. transistor. therelays, relay -coil currentThe same type of circuit provided the proper transistormay be isemployed to sensitize and (2) provide the current,provideselectromechanicalasis affordedlong andan as output the inputby outputother current control relay, power current, which signal transistors. consequently, is proportionalcurrentIn a flows. control will to the notUnlike circuit control make theof this type, output load current flows however, this transistor relay HEAT SINK LOAD ofrelay-unlessand handling break sharply-in (whichthe control is theidentical current manner withalso of thedoes.anFor transistorelectromechanical any desired collector load current that the transistor is capable 2N301 DEVICE P thecurrent, supplyload Ic),device: voltage the collector Vce (Vcc) equals minus-to -emitterVcc the minus voltage voltage IcRL. drop (Vce) And (IcRL isVce equal) across must to SIGNALDC CONTROL INPUT L J - emitterturer.respect2N301).never voltageexceed to The the theloadDC recommended maximum supplyresistance voltage safe and by operatingthe thethus maximum transistor must value be safe chosenmanufac-(32v collector/ for with the DC Si /I ON -OFF 4.6-AC/RF RELAY -L- DC SUPPLY frequenciesoveroperated a wide from tofrequency ACat least and RF 50range, MHz.control extending signals. from TheFig.This AC 4-6 low,circuit control is powerline the is useful circuitsignal isof rectified a sensitive by a relayshunt which-diode mayrectifier be 90 Fig. 4-5. All -solid-state DC relay. resistorcircuit,input consistingcircuitRl. The of DC the of output 2N3823blocking of field-effect thiscapacitor circuit Cl, transistoris applieddiode DI, (Q1) to andthe which gatelload as 91 (.0 1%) Cl R4 Q1 NA& 1K 2N3823 5 O ZERO SET RY

_)1000 1MA

1N542 CONTROL -SIGNAL r - INPUT D1 R1 1 (0.8V RMS, 1.611A)

TO CONTROLLED CIRCUIT

R2 R3

500 500 S1e<0 -o 0+

DC SUPPLY ON -OFF Fig. 4-6. AC/RF relay. (6V, 9MA)

2KC.T. Q1 R4 green T1blue 0.025 M%- ZERO SET UNUSED 2N3823 1K _11(0 RY C2C C1 AF Signal black 0.003 1000 Input yellow red 0.2V RMS 0 TC CONTROLLED D1Iv R1 1M CIRCUIT 0 111542

R2 R3

500 500 J - 0 0-10 - + ON -OFF

Fig. 4-7. Tuned AF relay. a DC amplifier drives the 1000 -ohm, 1 -ma DC/relay, RY(Sigma thethistransistor,effectRMS5F, ACor keeps willequivalent). transistor, control close resultsreasonably signal.the inAn much relay. almost AC Ashigh control Thesuperiorthe no the frequencyhigh loading input-signal inputto that resistanceof input ofresistance the theof of diode acontrol 1.6conventional presented of LIcircuit the asignal at field- 0.8v and tois balancedthansitivityofincreased, Cl thatshould of outrequiredparticularlythe be ofcircuit. decreased,the torelay beyond close coil. as the aboutrequired, Balance relay, 500Since kHz,toitis mustmaintainaccomplished the the transistor's becapacitance initiallythe sen- by zero -signal drain current is higher transistor.resistorsBalancingforwhichmeans isof R2,setthe isThe madefor R3,1000 circuit zero R4, possible-ohm, voltageanddraws wirewound,the by a across internalamaximum four -armthe zerodrain relay of bridge -set 9resistancerelay macoil rheostat consisting from (ordropout) simply theof (R4) the 6of -under zero control -signal conditions. voltreadilyaudio4.7-TUNED DC frequency seensupply. that AF because this RELAY arrangement it is reasonably addsFig. sharply the 4-7 AC shows tuned. RF relay a It relay is circuit which operates at a single miniature7.)Sectioncircuit consistingdescribed4.6 2000 for a-ohm complete inof (center thetransformer precedingdescription -tapped) T1 -to sectionof and -10,000theThe capacitorright to input -ohm ahalf tuned transformeroftransistorCl. Fig. input (See 4- (T1) is a reverse -connected 16B.responsecapacitance;proximately0.003-mfdoutput At transformer 1kHz curve capacitor foran of AFlower this control(Argonne frequencies,simple -signal ARinput input -109, increasetuner of or 0.2v appears equivalent). it. RMS A frequency inwill Fig. close The 1- 1 kHz. For higher frequencies, reduce the (C1) tunes the transformer to ap- voltthe4.8-PHOTOELECTRIC relay. DC supply. The circuit draws RELAY a maximum (SOLAR Aof transistorized -CELL9 ma from TYPE) the DC 6 -amplifier easily boosts the output of a circuitoperateself94 -generating in a Fig.given 4-8 DC photoelectric will relay operate with fromlowercell (solara -intensity comparatively cell), light. enabling dimThus, light.it the to 95 Type S1M, or equivalent), is amplifiedThe by a DC 2N190 output transistor of the cell, PC (International Rectifier driveunderproximatelycloseor equivalent).(Q1) theartificalthe to relayrelay actuate 0.5v illuminationOnly directly in in thethis abright 0.15v 1000 circuitwithout at sunlight-ohm,output lower (the the 1 from levels.-ma andtransistor.)S1M DCtheproportionately (Thecell cellrelay, celldeliversis RYrequired could (Sigma less to notap-5F, 6balancingthrough -volt4.9-PHOTOELECTRIC DC the circuitsupply. relay, is required.it is too RELAY Maximumlow to (PHOTOFETdisturb drainWhile the is 1 a measurable zero -signal collector current flowslatter, maso nofrom the sensitivityphotofetFig. 4-9 with(Siliconixis a photoelectricthe amplification Type P-102). field-effect and This high deviceThe inputtransistor, light-sensitive combines called device employed in the circuit shown in TYPE)impedance of light a asphotofet,acrossresistorsthe negative FET. R2,and R2 operating whichthere and R3 is is ain applied voltage10.5v series. drop as to positive theacross AR3, bias 10 which mato thecurrent is from the 12 -volt DC Consequently, a 1.5v drop occurs photofet drain. supply flows through gate of the applied close.Illuminationhencethroughequivalent). (The does thephotofet Aofnotrelay, measurableless need has thanbut ato it lens10 beis zero foot-candles tooinbalanced its-signal small to(noout will causeRelay -light) falseRY current is a 1000 -ohm, 1 ma unit (Sigma 5F,nose.) or The circuit draws a of thecause relay the coil. relay to closure, flows controlSOLID-STATE)4.10-HEAVY-DUTYmaximum large of currents, 11 ma from PHOTOELECTRIC if the 12load -voltIn DC a transistorized photoelectric circuit resistance is low with supply. CONTROL (ALL designed to loadHowever,allanelectromechanicalrespect current.allmoving -solid-state tothe parts the transistor transistor'slight-sensitive are relay eliminated collector internal control must collector circuitbe able to handle may be dispensed with entirely and from the control circuit. obtained.resistance, Thus the the 96 the(collector) load device circuit (RL) of a 2N1906is connected Fig. 4-10 shows a photoelectric circuit of this kind. power transistor. The amount of directly in the output Here, 97 Q1 HEAT SINK LOAD DEVICE ONw 0 black 2N1906 -- R-` L "64. hJ PC Si ON -OFF --_2*". red DC Supply (36V, 2A) if)CD 11 VICv Fig. 4-10. Heavy-duty photoelectric control (all solid-state). CC resistance,current amplification varying inversely obtained with RL. For example, when RL depends upon the load C.1 Theapproachesis (PC)10 maximum ohms need or125 be less, onlyDC(which the collector 1/125 current means of the currentamplificationthat required the isoutput 10 output (for of thethe load photocell2N1906) current). amperes for the zce1CO tromechanicalnotcurrentas2N1906. long make proportionalas andthe relay)relay,photocellbreak to unless however,sharply the is illumination, theilluminated. (in illuminationthis the circuit mannerIn and aUnlike providescontrol doesthe of also.the circuit elec- of this type, output load current flows output will output operatingminusvoltagetransistor IcRL. drop value collector And(IcRL) (40v Vce for current,across must the 2N1906). thenever load exceed Therefore,device:For the anyVce maximum the desired equals DC supply safeVccload current (which is identical(Vce) is withequal the to the supply voltage (Vcc) minusIc), the the collector -to -emitter Rectifiervoltagebythe themaximum must transistorType be S1M, chosensafe manufacturer. collectoror withequivalent), respect -to -emitter into theWith voltage loadcircuit a resistance self inrecommended -generating and silicon solar cell, PC (International Fig. 4-10, 4 98isloadthrough16 36 ma devicevolts output a 12 as and -ohm fromshown. 12v theload across cell device, will the producetransistorRL. This a placesloadwhen current the24v DC across of 2 the supply amp 99 4 any 4.11selected -TEMPERATURE temperature -SENSITIVE between 0 degreesFig.RELAY 4-11 F is and a relay 250 circuit which may be set for closure at whichtoTypeperaturedegrees be monitored.GB42JM1, automatically transducerF (by potentiometer or equivalent), iscontrols a 15,000 the R2).-ohmwhich current In thermistor, is this flowinginstalledThe circuit thermistor from RIat the(Fenwal battery pointtem- acts as a temperature -sensitive resistor ofproportionalthermistor.curreB1 R2 through is applied the toAs thermistor theas a the resulttemperature. control and the signalpotentiometer voltage to the dropThe gate R2 temperature acrossof in the series. 2N3823 R2 The -sensitive is negative voltageflow is at directly the proportional to the temperature of the output 4.3).previouslycircuitfield-effect Both R2 describedtransistor and R5 (Q1).(for are awirewound Thecomplete transistor description,units. With-relay the portion seeon -offSection of switchthe (S1 -S2) is identical with that of the FET relay circuit closed, the circuit is temperature.dropoutandbalanced(R1) then in of adjustinginitially the the region Whenrelay). by R5 first totheThe for be temperature settingzerocircuit monitored voltage R2then to isand isitsacrossAfter ready at zero carefully the the to-output level operate.circuitrelay measure at position coil which has (or beenthe balanced, place the thermistor mometer,meansminusDCwhichoperation voltage thelv of at isrelaya 0atdialdesired,temperature degreesthe just on gate closes.potentiometer adjust Fof to the chamberminus(When potentiometer FET 4.6v variesR2 R2 and is atmay set approximately 250an R2 atbe accuratedegrees maximum,to calibrated the point F.) ther-from theBy toat a 2N38234.12-TOUCH-PLATEread directly field-effect in degrees. transistor RELAY in a commonFig. 4-12 -source shows circuit a simple touch -sensitive relay, employing relay.touchedinsulatedwith(picked(areas a Atfloating withdown locationswire.up bythe to gate.The the finger0.06 whereoperator's device The square tip, gate therewhich works inch body) is are connectedcouples will when intostrong work) the theenough stray circuit toorplate aeven metalfieldsstray orto towireclose signal justfrom is thean plate 100topowercapacitance the linesplate or will otherrelay actuate sources,circuit. the merely relay, bringing resulting the infinger a simple close 101 balancedthan that out required of the relayto close coil. the Balance relay, hence Theis accomplished FET's must bestatic initially by(zero -signal) drain current is higher drainbridgefields.forwhichmeans relay resistance The isofconsisting dropout) setthe balancing for 1000 ofzero with ofthe-ohm, operationvoltageresistors FET.the wirewound,touch The across isR1, -plate circuitmade R2, the isolatedzero possible drawsR3,relay -set and coilfrom rheostatby the a(or fourinternal (R3) any stray simply -arm relay4.13-COINCIDENCE20 close ma from if --and the 12only -volt if-twoRELAY DC supply. control signalsIn a number occur atof the control operations, it is required that aa maximum of collector2N2712positive13same is atime. siliconpulse.simple voltage Neither Actuating transistorcircuit to signalthe for (Q1) same signalobtaining by anditself transistor. A actuatingsupplies thisis to performance.In close If thissignalbase the arrangement, voltage relay.B Fig. to a 4- each of the two signals is only actuating supplies a 1.5v 64. whenthanthe(Sigmasosignal no collector 1 currentboth A microampere5F,orequivalent); is applied,signals currentflows are thethrough (inand appliedtransistor theif cannot only absence1000 simultaneously, actuating hasaffect -ohm, noof collectorbasethe 1signal ma DC theB voltage isrelay,transistor applied, andRY relay. However,voltage) is less intervalexactlyhasof both 1 ma, inbase whichphase,and and the collector thethe relay two relay closes. signals bias, remains producingWhen do overlap.closed theCurrent two only drainduring is the not the same for the two a collector current signals are not actuating 4.14-CONINCIDENCEtuatingpresentsactuatingsignals. signal For asignal different actuating A Bit resultsis 187.5Kinput SWITCHsignal in resistance1.5v and A atitfor is1 actuating ma.1.5v to eachSimilarly, at 80 signalsignal; the B, for circuit 1.5K. ac- ua, whereas simultaneously.outputhowever,action to pulse the does one if-and describednotThe include outputonly in if-two Sectionpulse a relay. then1.5v 4.13. Instead,Fig. may input The 4-14 be itpulses appliedshows delivers occur ato coincidence an circuit which is similar in present circuit, an 102true.thatThisamplifier, is, circuit its outputexternal accordingly is truecontrol if-and performs circuit, only a orif-both recorder, of its as desired. logical AND function; inputs are 103 01 R1 2N2712 400K ACTUATING SIGNAL B INPUT + Actuating 1.5V FL1.5V Signal A 0 Input 0

5V SIGNAL R2 5K OUTPUT 0

I

Fig. 4-14. Coincidence switch ("and"circuit).

DC SUPPLY (1.5V, 300uA)

B jliS1)...---..--- ''...... * i 3V ON -OFF '--. R2 5K S2 1K

Q1 R1

SIGNAL OUTPUT

SIGNAL INpuT_r-rl'5V 0

Fig. 4-15. Signal inverter. asemitter base -followerbias, the circuit.1.5v actuating The 1.5v signal B asThis collector circuit employs a 2N2712 silicon actuating signal A is applied transistor in an bias, and onlytheabsencecollectorIf onlyactuating 0.5voutput actuatingofoutput voltage basesignal signal signal voltage) and signalis B practically isisthe taken applied,is Aoutput less is than the 1 collector current across the emitterapplied, resistor the transistor (R2). hassignal nozero. is practically However, zero;when ifboth microampere and again (in the dosignaltheandbasesignals overlap. twothe and is 0.5vare actuatingpresent collector applied output only signals bias, signalsimultaneously, during collector are the not interval and the when transistor the two has appears across resistor R2. When exactly in phase, the output emitter current flow, signals both B,signals.whereasthesignal it is circuit 17.6K. For withsources. actuating presentsactuating With signal differentsignal actuating A, B it itis issignal1.5M; 1.5vCurrent forAat it is 1.5vdrain is not the same from the two input resistances to the two 85 ua. actuatingSimilarly, signal actuating - at 1 ua, vicebe reversed-a 4.15-SIGNALversa, not positive merely INVERTER pulse positive must becomeIn some control operations, the -going or negative -going. The polarity of a signal must a negative pulse, or Thismaintainedrisesassignal thecircuit from inputinverter employs zeroassignal longcircuit to rises anegative.as 2N2712 inthe from Fig, positive zero 4-15siliconThe to provides positive, transistor this the action. input signalnegative is maintained. output signal is output signal(Q1). Here, that1.5vcollectorvoltageis practically the appears outputdrop is at atacross zero thevoltage the supply (actually, signal collector be voltage,zero less resistorwhen than1.5v the R2.Under zero -signal conditions, the 2N2712 collector output terminals, but it is desired positive.1 ua), Accordingly, and there is no Consequently, the current collectorcurrenttheSubsequently,potentiometerso the transistor bucking flows, becomes through when R3)acircuit voltage lessis a providedpositive(battery thepositive. drop signalBl, to This reduceswitch is applied this value to the base of signal input terminals, collector appears across R2 and the action upsets the zeroinput voltage is zero,S2, and wirewound to zero. 106samethebalance signal polarity inoutput the as output terminals.that ofbucking battery But circuit this Bl. It and is in this voltage is negative-the a voltage appears at way that a 107 inputnegative signal. output signal is obtained in response to a positive ma4.16-HEATERdrawssignal from 300of the minus ua bucking from CONTROL1.4v. the battery, The 1.5 -voltinput (MANUAL B1. DCreistance supply AnADJUST) is and 93.75K.input signal The of 1.5v positive at 16 pa produces an output approximately 3 circuit tinuouslyeconomy,muchpower smaller-consuming -variable compactness, rheostat controller. device or toand be cool manually operationTheSimple circuitcontrolled ofDC in theFig. amplification with 4-16 is allows a potentiometer,designed to controlthus promoting a 200v, 1000 - large current (and con- a resistancecollectorpowerrheostatcontrolwatt transistorheater voltage. (R1)current setting withcontrols (Q1), Here, flowingof a R1, 10 which the -wattthe through DC basein rheostat turnbase the controls the much adjusting the 200 -ohm wirewound current is 250 ma and the currentoperated of the from2N2016heater. a 1.5v At the zero - larger 4 flat,transistor.constantmaximum collectorpentode in of-like, Similarspite (heater) 5A collectorfromof circuitrysupply currentthe 135 voltage -voltis 5 fluctuationsDCAt all settings of R1, the heater volt/ampere maycharacteristic be used to of control the motors, amp. The circuit draws a currentsupply. tends to hold because of the Li. voltagesistortransistorshigherlamps, collector (Vce) currentsand mayother of current, theand be heavy 2N2016 used.voltages -current is are equal toelectrical be toFor the any desired heater current Ic), the DC collector -to -emitter (identical with the handled,tran- higher -power equipment. When supply voltage maximumbeTherefore,maximumequals chosen(Vcc) Vcc safe minusthewith safe DCminuscollector the supply voltage IcR2. -to voltage -emitter And inVce must respect operatingto the heater value resistance and the drop (IcR2) across the heater: Vce a circuit of this(65v kind must fornever exceed the the 2N2016). 4.17-AUDIBLEthe transistor manufacturer. ALARM Fig. 4-17 shows the circuit of a simple voltage recommended by power -transistor 1.08 halfalarmoscillator watt. signal. driving The audioa loudspeaker to power output is approximately one- give an adjustable -tone 109 HEP230 V1 FLASH RATE C2 1.0 2V, 0,06A 2K 0gN 100 T1 ON -OFF a Fig. 4-18. Visual alarm (lamp flasher). I't ,S1 0----7-1 +1 (9V, 60 MA) DC SUPPLY ped)ductanceminedtransistor. -to principally -8 of-ohm the In outputthisprimary by circuit transformer winding the Tiof theA circuit is capacitances Cl and C2 and the in- operating frequency is deter-employed with an HEP 230 20 -ohm (center tap- proximatelyCl50proximatelyor must equivalent).-watt, be wirewound 170a 300 non ma HzThe -electrolytic. from to resistor frequency3 kHzthe 12 byR4. -voltpositioning R3is adjustableisDC the also The circuit (Chicago-Stancordrawsa 50 -watt TAand -12,capacitor supply. tap on 1000 -ohm, from ap- ap- distance.lampsmall4.18-VISUAL can radio The give -typeflashing flashes ALARM pilot rate thatlamp. is (LAMP are Backed visible FLASHER) Thefor circuit in Fig. 4-18 provides bright flashes from a up with a reflector, the an appreciable powerminiaturewirewound20 flashes transistor 2000 rheostat,per -ohm second -toR1. -10 by -ohm A blocking oscillator circuit is (Q1) operated continuouslyadjustment variable of from 1 to employed,output with transformer, an HEP 230in T1 conjunction with the 5000 -ohm a 1109ma -volt(Lafayette (brown DC supply. -bead) 99T6101, pilot orlamp. equivalent). The circuit The draws lamp (Vi) is 60 ma from the a 2v, 60 - 111 4.19-CARRIER-FAILURE ALARMAn RF-operated device is convenient for signaling the 0 usedhorn)canof breakdownthe switch to ortransmissions operate a visual on of aan a timerdevice radioaudible themselves or transmitter(such recorder alarm as is a (suchnot to lampwhen Fig.log desirable. asorthe continuous4-19 a time bell, shows Such off. buzzer, a simple carrier -failure alarm flag), or it may be monitoring a devicecircuit. or cC carrier.connectedThis arrangement The to receiver an antenna is section essentially and is ground followed a diode and receiver tuned by a transistorized (L1, Cl, D1) to the RF 0 tothedeliverscarrierDC a base amplifiermuch is ofa on,correspondinglarger the (Q1)the 2N190 collector diode and transistor. sensitive rectifies negative current DCThe thewhich DC relay basereceived closes (RY). theRF voltage and current to current is amplified As long as the 1000 -ohm,signal 1 and CD,G) 1N295fails,ma DC the diode relay, collector (D1) RY must(Sigma current be polarized5F, drops or equivalent).and the If the relay opens. The carrier zcoM Lc) traordinarynothroughdeliver balancing the a negative relaycircumstances, circuit coil, voltage it is too to increased lowthe base to disturb of Althoughthe the a measurable zero -signal collector current is required. And except under as shown in Fig. 4-19 to temperature will not transistor. relay. Hence, flows ex- temptaccordingsuitableraisetuned this has commercialto current been tothe instructions carrier made sufficiently coil to tap found tothe close diodein radio the downThe handbooks. inductancethe coil of coil Ll must be frequency by variable capacitor Cl. Amay be used or one may be wound chosen so that it can berelay falsely. for im-No at- 4-20-INTERVALdrawstooproved sharply, a selectivity,maximum lest the TIMER of since station1 ma it from isbe better lost the that this circuit 6 -voltthrough DC supply. drift. The circuit not tune seconds.circuitprintersuseful(RY) formay closedand A the2N3823 enlargers,be for timedadjusted any field-effect selectedcontrol exposure (by rheostat interval oftransistor lamps, betweenFig. 4-20 is a schematic for an interval timer which equipment such as photo R1) to holdirradiators, the relay etc.(Q1) This is employed. 1 second and 101 is 112 depressedmfd capacitor momentarily (C1, Mallory to its Type set position,The arrangement is conventional. Pushbutton 10100, or equivalent) to charge causing the 10,000- switch S1 is 113 from the 1.5v Size -D flashlight cell, B1. When Si is released, it acrossmicrofarads.plusthesprings(R2) 10,000 R2)C Riin series. and -ohmseconds, The R2 wirewoundThe FET by discharge themonitors capacitor rheostat time the DCconstant(Ri)discharge voltage and 100is tcurrentdrop equals-ohm produced resistorwhich10-6 (RI back to its operate position and Ci discharges through where the Rs are in ohms and C in zerorheostatactuatesvalue.sufficientlySi (leavingreturns theRIThe relayandtoonly intervalto operate mayreduce R2time. in be of theThus,andthe variedclosure circuit) RIdrops the plus from relay depends toout R2 101 1 whenisvoltage sec secpicked upon whenwhen Cl drop hasup the 111Ri as dischargedto settingis issoon a set setcritical asto of static1000relaythe10,000 drain amplifier.-ohm,RC currentohms. timing 1 ma The of circuitDC the high relay, FET, willinput flowingRY not resistance (Sigmabe adverselythroughIn ofthe5F, the zerotheor FET shuntedequivalent), coil -signal insures of theby state thatthe (Cl completely discharged), the theohmrelay:circuitwould relay wirewound With keepis coilprovided Si the (orat relayrheostatoperate simply to closed buck andR5 for isCl thisfalsely.relay adjusted completely current dropout). Therefore, Thefor initially zerocircuitdischarged, voltage a draws outbalancing of1000across a themaximum - of 9 ma from the 6 -volt DC seconds,timetointermittentsupply. calibrate interval so The that 1.5vtheuse withinthe dialonly cellrheostat its(B1)of to range. thecharge maywill timing begive capacitor set longcontrol quicklyA service,precision Cl. (R1) to any owing directlystopwatch desired to itsin or other time standard may be used onephase 4.21-PHASEmaintains shifter. aUnlike constantSHIFTER the outputnon -electronic amplitudeFig. shifter 4-21 over circuits,shows its entire the this circuit of a continuously -variable range.)reactancesmegohmphase100the rangeHz-angle phase and in0 degrees5andthe controlkHz. componentsfrequency (At to rheostat 180frequencies degreesrange. and(R4) wiring shifts outsideAdjustmentat any the restrict frequencyof frequency that of therange, the betweenphase over0.5- stray 114 maximumsmooth control gain, of the the maximum signal output input amplitude. -signalThe amplitude 1-megohm With RI beforeset gain for control potentiometer (111) permits 115 output -signal peak clipping is 1.5v RMS and the line.1-mfdcircuitmaximum The blockingmustphase no-load be shifter DC capacitor -isolatedoutput draws (C3) from theResistors R2 and R3 must be -signal amplitude is 1v RMS.1.6 ma from the 6 -volt mayDC be inserted inprecisely the output matched. When the load (external device), corresponding supply. a Chapter 5 advantages-togethertheSince designers its very of first test equipment.appearance, with its high Its the size, overall transistor weight, efficiency-made andhas DCintrigued power Test Instruments lineanytionsadvantagescapablepossible -operated type of size,forof of economical theofinstruments,electronic weight, the first transistor time and test battery heatingself-containedas instrumentwell. have operation. in Today, effected many whichportable therestationary, Anddramatic hasis instrumentsthese scarcely not power reduc- samebeen - apresented;instruments.transistorized numberthe range ofnevertheless, of Eachways in possibilities some circuit with model. any circuits is oneusefulattainable of given themin theThe with inmay form circuitsother single be in combined chapterswhich described -transistor it isinto in this chapter give some idea of ponentstransistorsauthor'svaluesobtain special-purposegivenfrom models and inspecified circuitthis and chapter may components.systems. manufacturers vary are those somewhat Where obtained Current,are withparticularlisted, in voltage, testsindividual ofcom- thesignal amplitude, frequency, and phase those otherwiseelectricalohmsInappearcomponents all otherand to characteristicson becapacitances theinstances, necessary(or diagram their exact may toinor propermicrofarads;in beequivalents, the used. text,performance Except all resistors resistances when where of obtainable)are the shown one-half arecircuit. in any component having the specified 4.20,also5.1-DC1.14,watt, be and 1.18,usedand 4.21. MICROAMMETER capacitors1.19, as test 1.20. instruments 2.5, are 2.6,25 DCWV.3.1-3.4, (NPN)are found 3.6-3.11, Other in Sectionscircuits 3.16, 3.19, which 1.9, 3.20, 1.13, might 4.14, 116 converts the latter into a microammeter.A With transistor an electronic DC amplifier ahead of a DC milliammeter 117 CALIBRATION 100 R1 2N2712 M1 MADC0-1 +1 (2011A, 0.6V) DC INPUT S1 ON -OFF B1 -IL 6V microammeter of this type, the Fig. 5-1. DC microammeter (NPN). indicating meter is com- linear.milliammetertransistor.areparatively shown rugged.inA Figs.DC M1 input 5-1Transistorizedto full and of scale.20 5-2. DC microammeterThe circuit in Fig. 5-1 employs ua at 0.6v will deflect 0-1 DC Responsea Type of the 2N2712 circuit NPN is silicon circuits With the DC input terminals open, the meter is set to zero perature.scale,is so even low Hence, (lesswhen thanno the zero circuit1 ua) -set that is control it isTheThe 100 static -ohm (zero wirewound -signal) collectorrheostat operated atcannot extremes be seen of tem- on the meter current of the transistor(R1) is arequired. calibration deflectionaccuratelytheby1000 the static 10,000 -ohm collector of known the wirewound-ohm meter. 20 currentwirewound ua It into rheostatmay of the be rheostat DCtransistornecessary inputAfter (R4), andout tobeing which work ofadjusting thezeroed, backbalances meter. and thethe circuit is calibrated by feeding an (R2) for exact full-scale resistancehighscaledirectcontrol. valuedeflection current To whichand adjust intotheof limits thethis the meter. control, DCthe instrument feed toThe input resistance of this circuit accompanying 0.6 -volt drop can be input and adjust R1 for exact full- an accurately known 20 uais 30K, a comparatively uses where such a drawsthewhichforth accompanying between alimits maximum the the instrument of0.13R2 6.5 and -volt ma R4 from todrop adjustments. uses the can where6 be-volt tolerated.The thisbattery( input resistance The B). resistance circuit and of the circuit is 6.5K, a condition 5.2-DCvolttolerated. battery MICROAMMETER The (B1). circuit draws (PNP) a maximum of 3 ma from the 6 - strumentinputwhich5.3-ELECTRONIC divider, resistanceis comparable provides R2 of through fourbetter to DC a ranges VTVM,VOLTMETER R5,than and 12: offering 1Mmegohms Fig.in asthe 5-3 it probe). (11,11Mdoes shows a constantThis thein thein-circuit of a transistorized voltmeter 0-1, 0-10, 0-100, and 0-1000 118fullinput2N190 scale. of PNP20 The germanium circuit transistor. InFig. 5-2 is a microammeter circuit at 0.13v will deflect 0-1 DC milliammeter response is linear this arrangement, a DC employing a Type Mi to 2N3578volts, indicated field-effect by a transistor 0-1 DC milliammeter, (Q1). TheThe voltage high Ml. input under resistance test is is achieved through the use of a 119 SHIELDED CARLE R1 PROD (+) Fig. 5-3. Electronic DC voltmeter. 1M tow

PLUG JACK GROUND CLIP (-)

J2 m- R7 J1 01V 5K M1 R2 10M 01 0-1 ZERO SET 10V S1 R61M 2N357 8 DC

R3 1M RANGE Cl 0.002 R8 o 1 0 0 V 1K R4 100K CALIBRATE -o 1000V R5 11.11K R9 500 R10 NAM Wv 500 816V ON -OFF/ S2

0 ANTENNA

R3

D1 'Vrf- 10K ZERO SET , 1 N34 A (See 0-1 100 PF M1 LlO Text)Clti DC TUNING MA 0 PLUG-IN COIL R4 10K

R1 AAA, 500 500 / S1 or0 1 61 6V ON -OFF

Fig. 5-4. General-purpose field -strength meter. circuitapplied (resistors to the transistor R2 to R5 gate and singlethrough -pole, 4 -position, non - the range -switching of the shorting,mayratedpercentrangeinstrument be at selector, rotary 1tolerance -watt. is selector dependent resistorsThe is recommended).bottom switch R2 largely resistorto S1). R5 Sinceupon in the thethe string accuracyprecision (R5, 11.11K) of the made up by series -connecting an 11,000-, a 100-, and a should be closelyEach rated of these (1 resistors is pluggedDuringjustinginitiallythe10 -ohm test theprobe thisunit.balanced in, adjustment, butA directly 1-megohm must out ofbehindhave the isolating nometershielded the voltage prod. resistorin Static thetest applied usual(R1)probe (zero isway shouldinsertedto -signal) by ad- be drain current of the transistor is 5000 -ohm wirewound zero -set rheostat it and (R7). in probepreferablyandcalibrated:zero(R8) and(3) adjustment foradjust groundshould exact(1) theSet beclip full-scale 1000is switchclear to an-ohm of accuratelyS1 deflectionany towirewound interferingits 1v known ofrange; the calibration fields. lvmeter. (2) DC connectAfter source, rheostat the the completed, the instrument may be pickedformcoaxialmetal10 ma an case, upor RCfrom byconcentric and thefilter the inputthe 6 for -volt inputunits. leads.removing battery plugResistor This (J1) (81).circuitstray R6 andFor andAC draws jack best micawhich (J2)a shielding, maximumcapacitor shouldmight be Clbetheof instrument should be built in a replacednonlinearitynonlinearvalueshunt of-diode with the a ofapplied rectifier.shielded the diode; AC ACThe voltage; therefore, probemeter containing willhowever, special ACthen voltageindicate ACthea conventional calibrationscale may the will peak be be is measured if the DC test probe is at low voltages because of the low -current consistsrequired.5.4-GENERAL-PURPOSE of a tuned diode detector FIELD followed -STRENGTHThe field-by a transistor strength METER meterDC (FSM) circuit shown in Fig. 5-4 combinationsensitivityoscillator,checkingplications,amplifier theand inthan such approximateiswhich DC needed.that asmilliammeter. highobtained adjusting sensitivity frequency with transmitting This a simpleisof not circuita transmitter required diode is antennas useful -and but or -meter powerinbetter andap- 122 pickscircuit. up the Diode RF signal D1 rectifies which is thetuned RF -in signal sharplyA smallvoltage with pickup the and L1 applies antenna -C1 (short vertical rod or stiff wire) 123 transistorthe resulting (Q1). negative The base DC currentvoltage is amplified to the base of the 2N190 pickup. The circuit should remain zeroed for long zeroperiods. -set Therheostat (R4) in the absence of any RF RFohmis sistorinitially pickup. wirewound which balanced The then circuit deflects out the The zero -signal (static) zero -set rheostat (R3) in the absence of the meter thenby will remain zeroedcollector current0-1 DCof the milliammeter adjusting the 10,000 - by the tran-(M1). transistorfor long of any -1,-wirewound 5.6-DIPflashlightcontrol.5,000 OSCILLATOR-ohm DC cell operating rheostat (B1). Maximum power(PNP)(R3) servesis supplied drain Theas ais utilityby sensitivity 3 ama. 11/2 of the-volt, (orgrid size gain) -dip -D oscillator (GDO) is well known directionsacapacitorperiods. commercial given Cl, to coilin the Table or carrier Inductor Ll is selected to a home-made one wound 5-1. frequency of interest. This resonate, with 100-pf tuning according to may be shownfromsizetransistorto electronic the andin powerFigs. weight. which 5-6 workersline anddivorces Transistorizedand 5-7. ofoften all the classes,permits dip oscillatordip aand dramatic-oscillator it is (DO) increased reduction circuitscompletely by in theare inchCOILclosewoundCOIL diameter B 3.8 A to1.8 on 4.6form. toa MHz1 4 -inch MHz diameter TABLE 5-1 25 turns No. 26 enameled 57 turns No. 32 enameled form. wire on a 1 - wire usual(R2),commonfrequency andmanner. -base sensitivity PNP circuit.In transistor fact, (R5) In the this adjustments instrument in instrument, a specialFig. areis adaptationtuningused 5-6performed shows in (C1), every a ofinmeter DC the circuit employing a 2N1178 high - ap- COILdiameterCOIL E 30 DC 15to8 form. to68 1834 MHz MHzSpace 12 to turns Space to a winding length of 51/2Space turns to No. a winding 22 enameled length wire of a winding length of one-half inch. No. 22 enameled wire one -quarter inch. one-half inch. on a 1 -inch on 1 -inch rectifiedtificationcircuitplicationthe microammeter and RFinof thedeflected thesampled same RF oscillator (whichway acrossby asthe usually thethe signalDC usual tuned resulting isvoltage) GDO.connected circuit Here,from is (L1 deflected in gridhowever,-C1). a tube rec- For bygrid orientingdiameter5.5-TV TV form.FIELD receiving Space -STRENGTH antennas. to The circuitThe field strength meter circuit 21/2 turns No. 22 enameled wire a winding length of one -quarter inch. METER in Fig. 5-3A is designed for on a 1 -inch frequencyband.midgetmeterthis purpose, circuit.,A variable set range C3,of plug-in of D1,capacitor the R2, instrument. inductors and (C1) MI form over coversCommercial aA a shunt plug-indesired the -diodeentire coilsinductor frequency rectifier/desiredmay (LI) be is chosen to resonate with a 100-pf fieldinstrumentL2)one strength describedand the forof DC in therooftop Sectionmicroammeter received The input circuit is usecontinuously and is entirely5.4, tunable, except adequate byfor means the when special of the 200- coupler (L1 signals is 1 millivolt and higher.(M1). It makes a is similar to the lightweight - limits.coilsTableused, will or5-1 a toextendset cover may the bethe rangewound 1.8 -MHz above according to and68 -MHz belowto Thisinstructions range. these dip oscillatorAdditionalfrequency given in is somewhat less sensitive and the inductorssinglehairpinChannelpf midget turn loop 13 are of(specifically, madevariablegiven insulated from in capacitor No.hookup from 20 bare wire Fig. 5-5B). Coupling coil L2 is mounted 40Cl, MHz from to Channel 260 MHz). 2 through Li is copper wire and L2 is a(dimensions of these a 5.7-DIPcircuit,becausetuning isbut OSCILLATORof more itthe is loadingcriticalinexpensive thanof (FET) the theand tuned equivalenteasy circuit to Thebuild. tube bydip the circuit,oscillator diode/meter chiefly circuit in Fig. 5-7 has the sensitivity and radiothepensive.contactrigidly base -frequency silicon ofThe inside the negative 2N190 microwave filterLI, as DCDC shown output in currentFor operation at the highamplifier TV frequencies, transistordiode, D1(Q1) Type is through 1N21B, but it is inex- Fig. 5-5A. of the diode is fed into a point - a theeffectGDO,tuning conventional thankstransistor sharpness to the (QI). whichtube high circuit.input are characteristic impedance That is, Thisofa Colpitts theof circuit the2N3823 tube istype seen field--type RF to be equivalent in configuration also to 124 is theinitially transistor balanced which out ofthen the The zero -signal (static) (RFC1-C2). This current is deflects thecollector microammeter. currentmeter of by the adjusting transistor the 1000 -ohm amplified by dualoscillator 100-pf is variableemployed, capacitor tuning is(CI), accomplished sensitivity iswith adjusted a midget by 125 o

TUNING 1.1 ClI 100 P F

PLUG-IN COIL C3 10 PF (See Text)

R1

/V0 C5T-5PF S1/ 391< ON -OFF

R4 270 R2 R3 METER C2 0.01 3.9K - C4 250 le ADJUST SENSITIVITY 0-50 B1 7-7 9V R5 DC pA 1N34A 2.5K 4

Fig. 5-6. Dip oscillator (PNP). Aow

C2 R2

1)---JVI.jAral-< 200 PF C4 Ll I0.002 TUNING PLUG-IN COIL Cl (See Text) DUAL 100 PF Si C3 2N3823 o ON -OFF 200PF

R1

J10___. 500 l<

SENSITIVITY HEADPHONE JACK M1 0-50 DC pA B1 Z. 6V

Fig. 5-7. Dip oscillator (FET). N) N 03 Ll 4=0,1,PLUG-INCOIL R4 (See Table5-3) ------AAAV D1 RFC1 ZERO SET 10K 144(0001 2N107 1N34A 2.5 NH

RF INPUT (From 0-1 Signal Generator) 111 R1 120 C2 DC 0 100 PF 100 PF MA

R2 R3

470 470

Fig. 5-8. Dip adapter. B1 ON -OFF 3V

I CALIBRATION FREQUENCY RANGE CONTROLS

C3 A R4 10K 0.5 S4 S5

C4 R5 10K

20K D1 NIF D2 4Ik 0.05 1N34A 1N34A 0-100 DC 11A AF INPUT C5 C f --oD3 0.0051N34A R6 10K FREQUENCY A.0-100Hz C6 D 8.0-1000Hz --4(--o 0.0005 R7 C.0-10kHz 61.7 62 63 - 10K D.0-100kHz 9V + 1.5V 1.5V + I 1 T Fig. 5-9. AF frequency meter. 5 N.) microammeter.themaymeans headphone be of plugged a 500K into series jack meter J1 for rheostat auralCommercial GDO plug-in coils plug automatically may be used, monitoringor a set(R1), of aand signal; headphones disconnects the 86COIL100 turns AkHz No. to 32 6 MHz enameled wire closewound on 1 -inch diameter TABLE 5-3 preciselytuned)handbooks.rangecovering of coilsfor 10-50 the Tablethe whichrange pf)frequency 5-2 according 1.1 lists to six 100bands to MHz instructions shown. may be mounted on plugs and adjusted J. W. Miller Co. may be wound (for a Cl found in adjustablethe radio (slug - 115COILform. to turns 35 B MHz No. 24 enameled wire closewound on 1 -inch diameter COIL1.1COIL to 2.5B A MHz TABLE 5-2 No. 20A474RBI20A104RBI 30form.COIL to 250 C MHz COILCOIL52.5 Dto toC11.5 5 MHz MHz No. 20A225RB1 to21/2 5.9-AFa windingturns FREQUENCYNo. length 24 enameled of 1/8 METER inch.wire on 1 -inch diameter form. Space 20COILCOIL to10 45 E to MHzF 25 MHz No.No. 20A156RBI 20A476RB1 fourinstrumenttuningsignalgreat ranges:0-100Hz. convenience, can or calculations.be which read coversdirectly since 0-1000Hz, Fig. the the from frequency 5-9frequency 0-10 the shows dialkHz Aspectrum oftheof anddirect aan circuitDC 0-100 unknown -reading, meter0-100 kHz.of such withoutkHz, All analog anare in -type audio frequency meter is a audio use5.8-DIP as a dip ADAPTER oscillator. RF The circuit in Fig.40 5-8 to 100 MHz adaptsoutput any fromRF signal the signal generator generator for is No. 20A337RBI calibratedTheofsignalread meterwaveform. from amplitude responsein the each 0-100 aboverange. is 1.1linear, 0.7va The scale so RMS response only of and one it is largely independent DC microammeter is independentpoint of need Ml. be coilsdirectlymilliammeteroscillator,theapplied providecircuit from to and theunder athe testMl. theRF signal test inputThesignal in resonanttheterminals, inductor range extending from 100 kHz to 250 MHz. generator tuning dial. Threenormal plug-in mannergenerator of using is tuned for dip of frequency then is read Ll is held close to a grid -dip consistingsignal.which,AFwhich signal is consequently,The common higherof latterresistor than to is tubeR3, 0.7vsquared delivers diodes-type overdrives AF further D1a quasifrequency and the TheD2,by square2N190 theinstrumentand meters. limiter amplifier11/2v-wave The penlight circuitutilizesoutput (Q1)input a well-known operating principle sistorsignalprobe3. InstructionsThe (Q1) ongenerator.entire is the initially adapterend for windingof balanced a shielded the cableStatic (zero -signal) collector can be built in the form of plug-in coils are given in Tableout 5-of the 0-1 DC milliammeter current of the 2N107 tran- which connects to the a hand-held onlyamplitudeBecauseandpresentedcells D4, toB2 the theDCand to square signal inputthe microammeterB3, meter wave,frequency.signaland circuitthe theto resultingthis meter (capacitorsM1, circuit anddeflection square consists rheostats C3 to-wave is C6,of proportional R4a diodes constantsignal to R7). D3 is - 130Maximum(R4)(M1) bywith drainadjusting no issignal 6 thema from the 10,000 -ohmapplied wirewound to the zero RF -set input rheostat terminals. 3 -volt battery (B1). positionposition, selects nonshorting, one capacitor rotary (C3selector to C6) switch Frequencyand one (S4 correspond -S5). ranges are - selected by means of a 2 -pole, 4 - Each 131 500 -ohm winding serves as the transistor base -input coil and rheostatsexactlytrolyticTheing 10,000 capacitors allowascapacitors, shown. -ohm adjustment need wirewound and not the be of microammeterhigh eachcalibration -precision range.The rheostat All must bestunits diodes, point be because(R4 polarized for elec-to R7),calibration is full-scale deflection of the the singleisthe coupling.(S2).tuned lower -pole, The by 30 8a -position,-ohm transformer non -shorting, half as the collector -output coil. The entire windingcapacitor (C1 to C8) selected by means winding is used solely for output rotary selector switch of a adjustsignalswitchWithRangemeter rheostat(higher the -100 C,(S4 3PST and -S5)Hz thanR4 100 foron tofor 0.7v-offkHz RangeA. exact (2) switchforRMS) ApplyA, Rangefull-scale 1000 (S1 to anthe D.-S2 Hz accurately CalibrationAFdeflection -S3)for input Range closed, terminalsknown of Procedure:B, setmeter 10 the 100kHz Ml.and -Hz (1)for range capacitorswitchtheselectedcapacitances 500 (S2)-ohm capacitor is in selectedwinding position must in theofandbe D, Cl as to shown C8 groupThe oscillation frequency is determined principally built up bytransformer parallel -connecting Ti. Thus, severalthe with frequency the range is 1 kHz. Three of the in Fig. 5-11, the 0.08-mfd and the inductance of by the adjustS5andSwitchHz, to andadjust(3) D, R7 S4Switch adjust change -S5 forR6 to exactforS4R5 C, the-S5exact forchange full-scale inputto an full-scaleB, exact thechange-signal input deflectionfull-scale deflectionthe frequency -signal input deflection of frequency-signal ofMl. to Ml. 100 frequency (5) of tokHz, 10M1.Set kHz, andS4 to(4) 1000- fromthesmallerother0.00047(0.0032 following 0.22 capacitances.appropriate mfd) andand values: 0.00033.from0.1; C40.00221.0, capacitances. Thus, Other(0.08 0.2, and 0.08,Cl stepmfd) 0.001;(1.281 frequencies are and 0.001 mfd; C3 (0.32 mfd)andfrom C7 0.047 (0.0008 and mfd)0.033; from C6 mfd) is made up from obtainable with formerhandle5.10-AUDIO -feedback and usedSIGNAL oscillator INJECTOR which may beFig. built 5-10 into shows a probe the circuit of a miniaturized 1 -kHz trans- to troubleshoot audio amplifiers and NegativeblockCapacitorpolarized the collectorcorrectly;C9 feedback is not DC followpart provided voltage of the colortunedfrom by coding thecircuit,For base =bypassed oscillation of the to occur, the transformer must be shown in butFig. serves 5-11. only to transistor. emitter orohmtransistorassociated equivalent), winding is equipment operated ofand miniature the hereby 0.05-mfd the from transformer signal a 11/2 capacitanceinjection -voltThe Ti (Argonne frequencypenlightmethod. cellA isAR 2N190 determined(B1). by the inductance of the 2000 (C1). The -109, - resistor (R2) acts to minimize distortion.The 10,000 -ohm wirewound potentiometer (R3) serves as Whenproximatelytheternaltransformer color testing loadcoding 18 sensitive must ofmy shown 39,000 RMS be polarizedaudio inwhen ohms;Fig. devices,the 5-10. correctly loadthe amplitudeis it reduced The sometimesfor oscillation;output to drops 1000 -signalis not ohms.followto amplitude is 0.4v RMS across an ex- ap- intothenecessary5.11-STEP-TYPE prodthe circuit. close to connect Current to the AUDIO directlytestdrain point is OSCILLATOR 8 into II will a fromthe couple circuit-merely the 11/2 sufficient -volt cell. placing signal blue Pl 100K C2 0.1 C==>PROD 250,individuallyoscillator 400, and which by500 means Hz delivers and of 1, a 2, eightrotary 5, 10, fixed switch.and 20 frequencies kHz.Fig. The 5-11Afrequencies 2N2712 is selected the silicon circuit are of a Hartley -type, sine -wave AF B1 1S1 1.5V ON -OFF GROUND CLIP former,132tuning,transistor Ti feedback, (Argonne is employed. and AR output -117, functions. or equivalent)A The miniature upper provides half500 of-ohmthe the (center tapped) -to -30 -ohm trans- Fig. 5-10. Audio signal injector. 133 0- an output -amplitude control and gives smooth variation of the signal.ponentblockingsignalMaximumG, and infromOutput theH,capacitor anddrainzero -signal tois to 2 amplitudeprotectma from the 6 -volt battery external circuit tois which somewhat the oscillator lower on supplies Ranges a A, B, C, and D. maximum. Capacitor C10 serves as a R3 and T1 from anyis DC0.8v com- RMS on Ranges E, F, (B1). Cr,S-a) oscillator5.12-INDUCTANCE/CAPACITANCE or signal generator for inductance CHECKERThe circuit and capacitance of a simple device which adapts a test C D checks is shown in Fig. 5-12. Inductances from 63 uh to 6300 by COCD totheand terminals aidcapacitances of a 1common, and from2) which service 150 tunes pf -typeto from5000 audio 20 mfd Hz oscillator can to 200 be checkedkHz. (connected with CD O . 1 ortween between an unknown an unknown inductance capacitance (Lx)and (Cx)Withstandard andthis capacitor device, a Cl, series -resonant circuit is set up be- standard in- z- L.CD 0 C.1 DCductor milliammeter Ll. The combination (M1) acts ofas diodean AC (D1), microammeter transistorCAPACITANCE (Q1), to check and COMMON INDUCTANCE P O 0 CK Ll 3.2 '0 50MH 4° Cl 5° tT 0.01 H- 2N2712 111 1 °SIGNAL DC MA0-1 C -) 2 o GENERATORINPUT 47P1 1N34AD1 S1 10N -OFF LL 134 II, Fig. 5-12. Inductance capacitance checker. 135 A the resonant current. An unknown capacitance is connected to 100,000 INDUCTANCE 10,000 CAPACITANCE peakterminalsunknownpoint,terminals deflection an 4 3andinductance and 5. 4, Then, or an Lx the unknown equals input frequency unknown capacitance Cx equals of meter Ml, indicating resonance. At 109/395 f2,inductance where Cx is is connected in to 106/1.975 f2, or an is varied for a this microfarads,correctfrequencycalculationsthe frequency and chartchart willLx may in giveingivencan henrys,Fig.be bethe avoided read L and by using in Fig. 13B.5-13A These and thecharts capacitance are approximately -vs -from most oscillator dials andand as f C values at least as closely as in Hz. These tedious the inductance -vs - 10,000 1000 Lluponunits.closely (J. theW.The as precisionMiller f,accuracy Cl, No.and of758,Ll this usually or device equivalent), can An oscillator output voltage of approximately of 0.01-mfd capacitor Cl, 50-mh RF inductor will drive milliammeter M1(and to of the method)be obtained depends in inexpensive and the oscillator. 0.75v RMS 1000 100 fullbattery(applied scale5.13-RF at(B1). to resonance. SIGNAL terminals The1 and circuit 2) draws COMPARATOR 3 ma from the 6 -volt thousandtheinputssignals two and by signals. Hztheshunt beatof -diodeWhenthe -note other one (or signal may An untuned mixer/amplifier detectorsmethod (D1 and appears D2) are in provided Fig. 5-14. Separate unit foris comparingwithinthe atwo few two and Hz RFthe tobe a beatadjusted few note isto be so), an for 100 10 100 10 10 20 30 40 100 Theappliedaudible beat beatto notethe note gate may is setof thebeup monitoredbetween 2N3823 field-effectshown transistorin Fig. 5-14), (Q1). further am- with high -impedance INDUCTANCE FREQUENCY20 30 40 CAPACITANCE FREQUENCY magneticmeasurementofplified, calibrationthe beat orheadphones applied -note of procedures, anfrequency. to RF an(as oscillator against Aa device of this AF frequency metertype for measurement harmonicis useful frequencyidentification, standard.in RF frequency and 1-10100-100010-100 kHz: Hz: Hz:2.5 25,000-250 250-2.5HY-2511H HY HY 1-10100-103310-100 kHz: Hz:0.5-0.005 Hz: 5000-50 50-0.5 MFD M=0MFD The5.14-STATIC circuit draws DETECTOR 2.1 ma from the(ELECTROMETER) 6 Fig. 5-15 shows the circuit of a sensitive, electrometer-volt battery - (B1). 100-100010-100 kHz: kHz: 25-0.25 250-2.51JH MH 100-100010-100 kHz: kHz: 5000-50 50-0.5 PFFT verytypeleaves.advantage instrumentmuch When like that the for an pickup detectingindicating rod (3 to 5 inches the old-fashioned electroscope, but meter is staticused insteadelectricity. of gold It behavesfrom the instrument case) of rigidly mounted with the 136 Fig. 5-13. LC charts. isrod proportionbrought or stiff wirenear to thesuperbly a charged static insulatedvoltage body, the and the distance between the meter is deflected in 137 G PICKUP ROD wV) 14".0.111111 2 + CO at . I 2N3823 R2 oCL tf) 2K esi Cy-) 0-50 DC IA eNiMco IX co R1 5K ZERO SET '11t+ 9V B1 S ON -OFF 147 throughrodcomb and one'sisthe about body. hair one willA dryinch deflect comb from the chargedthe meter tip of toby the full running rod. scale The itwhen brisklytip of the the Fig. 5-15. Static detector (electrometer). OIC rodtubeinprefer should (B1).a floating circuit. to The becap polished-gate instrumentCurrentthe rod circuit, with todrain ais equivalent smooth ainitially polishedis 2.5 roundness mabalanced to brass froma Thisfloating ball). the by(somedetector setting 9-grid -volt designers employsvacuum meterbattery M1 -a 2N3823 field-effect transistor (Q1) 01zM'Tr STANDARDS5.15-HARMONICpickupto zero rod(by clear adjusting of allAMPLIFIER wirewoundfields and the FORpotentiometer operator's FREQUENCY body. R1) with the 11-4 1-1 for RF calibrations (see Sections 3.10 and100 3.11).-kHz and Sometimes, 1 -MHz frequency standards are widely used be 138 IX 0 0 circuitharmonicuseful.however, ofWhen asuchfrequency desired this an amplifieroccurs, check will -pointanboost external harmonicthe signal. amplifier is Fig. too tuned weak5-16 toisto the 139 which(Q1), delivers it offers the virtually signal to noits loadRF input to Sincethe terminals. frequency this circuit The standard outputemploys a 2N3823 field-effect transistor HEAT SINK tll from5-1of 100-pfthe provides the amplifier 9 variable -volt winding isbattery capacitortuned data (B1). to the forC4 harmonicandLi. Theplug-in circuit frequency inductor draws byLl. 1.5means Table ma 220 R1 R2 1K Q1 2N1906 0-1 DC AMP dutyjustablepower5.16-ELECTRONICthe rheostat. rheostat supplies, load. Usually Andmay a variablebecause be it LOADhard must ofresistorto be RESISTOR theset a large, coarsenessclosely, often cumbersome,While (PNP) isespecially usedof testing its aswinding, theheavy-an at ad-lowvolt/ampere - output characteristics of DC - 1 1/2as V B1 DC INPUT PNPusingresistorpowerresistance transistor,a transistor, 2N1906adjusted points. the germanium byConsiderable which meanscircuit can ofis power easilymosta improvement light transistor.usable function-dutyFig. inrheostat. 5-17is testingSince asafforded ais variable suchthis by isa circuit-aa fully electronic load resistor power Fig. 5-17. Electronic load resistor (PNP). cuit,negativeSectionsupplies the whichsupplies.)output have(collector) And a grounded since resistance this -positive is a common is controlled DC output.-emitter by (See ad-cir- 5.17 for a unit which accommodates grounded - HEAT SINK M1 justment of the DC base current. The 11/2 -volt battery (B1) C5I( Ri 1K 51R2 2N1070 0-1 DC AMP 100 PF ClI( 2N3823 C41100 PF Ll 47 PF ote`(See Table = 81 3V DC INPUT -o RF INPU1 R1 1M TUNING 4 RF OUTPUT 5-1) 1K R2 0.1- -0.02C2 C3 Bit:9VS141 \ ON -OFF Fig. 5-18. Electronic load resistor (NPN). 140 Fig. 5-16. Harmonic amplifier for frequency standards. 141 ohm,supplies wirewound, the base current volume which -control is adjusted -type by means rheostat of a 1000 - (R2). capacitor(C4) is (C3)a 350-pf is used midget as a fixedvariable; -tuned a second trimmer. midget Inductor variable L1 heavierDCwhenRiMaximum is input aR2 safety -duty is currentvalues set performance,resistor to drawnareits zero36 to from volts, prevent-resistance useBi 1is a ampere, 7overdrivinglarger ma. point. The Thepower and 220 0-1 50the -ohm,transistor. DC watts. transistor ammeter 1 -watt For (M1) reads load current. Maximum inchconsistsinchclosewoundtom diameter end;from of 58 L2 theturns form, onconsists bottom theof withNo. same of26 a 15Li. tapformenameled turns at asthe Liof wire30th andNo.For closewoundturn spaced 26best enameledfrom stability, one the on -eighth bot-a wirecapacitors1 - Cl, C2, C5, and C6 should be Fig. 5-185.17-ELECTRONIC is an electronic load LOAD resistor RESISTOR circuit for(NPN) testing DC goodmanner:orconvenientmica 3 to RFunits. 1. (1)signal interstage FeedOutput generator an couplingunmodulatedaudio into unit the transformer having RF 1000 signal aInitially, turns-kHz inputTi ratiosignal may the terminals. of instrument befrom 2 toany 1a can be calibrated in the following repeated.madesiliconpurpose,power in unit,supplies anthe The NPNQ1). preceding differences having power groundedsection,transistor in the Fig.apply is-negative required 5-18 hereThe circuit, andoutput.(here,overall will aside a Forremarks2N1070 not from this be regarding electronic load resistors, Adjustforstandard1000(2) aSet trimmercloserkHz tuning for at zero thisthe C3 capacitor signalsetting.beatfor zero with generator. (4)beat.C4 the Substitute to standard.The maximum (5) C4 Reset diala (6)100 may capacitance. C3,Tune -kHz beif C4 necessary,frequencymarked slowly (3) drawnresistor;5 -watt,the polarity from wirewound and B1 Bidifference is is 35 a rheostat; 3ma. -volt in the battery. R2 DC is input, a 51The -ohm,Asare: maximum in Ri the2 is -watt a preceding 1000 current safety -ohm, circuit, the 0-1 DC ammeter (Ml) markingfrequencyfrombe1100 read its kHzthe 1000 directly harmonicdial on -kHzthe1200, from C4 1300,settingis dial. thetuned 1400,C4(7) until indial.Repeat etc.,at the Itzero towill atnext 2000 beat.each Afterbe higher kHz.necessary standardMark completing standard this harmonic,then point calibration,only - the unknown frequency can readsdutyhowever, load performance, current.are 50 volts, The use 1 maximuma ampere, larger power and DC 50 inputtransistor. watts. values For heavier here, - frequency.thethento (B1).tune unknown needs C4 toThe bezerosignal circuitmultiplied beat is a withdraws harmonic or the divided2 signal.ma or from submultipledepends Whether the 6 upon -volt this of whether thereadingbattery dial theRFuses signal5.18-HETERODYNE the familiar ofby a comparing single beat -range -note the FREQUENCY variable methodunknown -frequencyto (bymeasureThe METER zero heterodyne beating)RFan unknownoscillator. frequencywith meter circuit shown in Fig. 5-19 higher)the5.19-AF AC voltmeter intoSIGNAL a high portion-TRACER -input of -impedance aADAPTER VOM (5000The FOR ohmssimple VOM -per adapter -volt, circuit or shown in Fig. 5-20 will convert (5 megohms) audio oftheplified.TheDl) the unknown andnotetwo frequency Harmonicsthe RFmay beat signals signal, be meternote monitored of aremay is thefar availablemixed beoscillator,above withused, in and atanheadphones and theuntunedbelowas thiswellAF extendstheoutput as detector or fundamentalharmonics further terminals. the (diode range am- of - adjustablepedancefollowers,sourcethissignal circuit tracer.-follower of theemploysfromis To lesscircuit circuit.zeroobtain than a is 2N2823to 560 the unity-inmaximum ohmsnecessary field-effect atthis 1000by case,high means Hz. transistor input 0.7. Gain of Outputimpedance, 5-megohmis (Q1)smoothly im-in a Its amplification, like that of all combination)frequenciesfrequencytuninglimits, therange band fromharmonics is of of1000 50 thethe kHz tooscillatorRF become2000 oscillatorto 30 kHz. MHz. (determinedtoo Thein weak Abovethe mainThe instrument. for by tuningandcircuitpractical the below L1capacitor given -C3use. these -C4inThe Fig. 5-19 may be used to measure mayrangemeansthepotentiometer tracer be switching. of made gain sensitivity inRl.control eitherComparative mayR1, volts andbe or adjusted(2) gaindecibels. by and meansWhen in loss two ofthe measurements ways:the signal voltmeter (1) is beingby traced through an audio system, 142 __..., i___ 143 01 II Cl 2N3823 1.0 ON -OFF? AF INPUT R1 10 C2 SlL (From o-- Ii' Cl-La- (-) ShieldedProbe) GAIN R2 1K 1.0 J. TO VON C-)VD Q 81 -9V Fig. 5-20. AF signal -tracer adapter for VOM. iogo C-) With RI set for maximum gain, the maximum input -signal LC) L.- amplitudethe corresponding before output maximum -signal output peak clipping -signal amplitude is lv RMS is and 0.7v C-.) CO 0- RMS. The circuit draws 1.7 ma from the 9 -volt battery (B1). (-1CD (NI 5.20-PHONE MONITOR ---i (--)C,) C.7 CO Fig. 5-21 shows the circuit of a tuned monitor for checking (i0O L0 amplitude -modulated radio transmitters and other power - -e-NAA9-40 CC tuneda suitablebytype diode in modulated by pickup theD2 Liand -C1antennaRF the generators.combination. resulting (usually audioThe Theshort RF outputsignal andsignal vertical) thenis is presented pickedis detected and up tois by a 1-1 O Thetransistor amplified audio signal amplifier then isthrough monitored coupling with high transformer -impedance Ti. CCLi- CV "- Rl.continuouslymagnetic headphones adjustable or by is means amplified of 1-megohm further. Audiopotentiometer gain is 0 Q9 ja LIC3 + ,I1 instructions.)to tune the RF Transformer carrier frequency. T1 may (See be Table Inductorany 5-1convenient forL1 Lland winding 100-pf in- variable capacitor Cl are selected 0 144 1terstage or(B1). 3 to audio 1. The transformer circuit draws having 2.1 maa step-up from the turns 9 -volt ratio batteryof 2 to 145 01

HIGH- IMPEDANCE

MAGNETIC

Q1 HEADPHONES PICKUP ANTENNA 2N3823 S1 ON-OFF

L1 101 e t0 01 C11100PF 1N34 A ok, LO41H1 R2 81z. 9V PLUG-IN COIL C2 c) R1 0.002 500 C3 50 (See0 Table 5-1) TUNING GAIN

Fig. 5-21. Phone monitor. 5.21-CW MONITOR Fig. 5-22 shows the circuit of an untuned CW monitor longpoweredItwhich isoutput. able as gives the toby dodot DCthe this or sameobtained dashbecause tone signal by itfrequency isrectifying is a present,fixed to-frequency the alltheRadio RF signalsoscillator CW -frequency AF monitored.signal. oscillator delivers Asenergy is picked up from the monitored filteredcoil).wireCW transmitter2" The by in 21/2diameter,RF ismh byrectified radio coil supported -frequencyLl by(2 diodeor close 3 choketurns DI to whose theofRFC1 insulated transmitter andDC 0.002-mfdoutput hookup tank is r-1 Fig.positiveohmcapacitor 5-22. resistor DC Cl. Theoutput, R1 resulting is theused diode DCto power voltagemust be thedeveloped polarized AF oscillator. across as shown 1000 For in - rn 0 r-I sformer,a Hartley T1 -type (Argonne circuit. AR In this-117, oscillator, or equivalent)The the oscillator,miniature is a 500 employing -ohmtran- a 2N2712 silicon transistor, uses CC LC) determined(center tapped) principally -to -30 by ohm capacitance unit. The C3 oscillation and the inductancefrequency is ("s1 furtherconnecteddecreasesatisfies0.02of themfd, byCentire many the 3 meansdirectly ; frequency primary ears. of to an However,jack winding isexternal approximately Ji, or of amplifier.the the signal transformer. 2000 Hz, a Withpitch thatC2 at to lower it, increase C3. Headphones may be to raise may bethe boosted frequency, CN1 V)Ct.1 circuitaelectronicof5.22-DC source such of is,devicesVOLTAGE acurrent in calibrator effect, as meters, aCALIBRATORDC DCof amplifiers, this signalmillivolt type. generator. Thispotentiometers, electronic calibratorAn Fig. accurate 5-23 voltmeters, has showsetc. DC selec- Such voltage the source is needed in the calibration toconsistingtable, R7. fixed The DCof current precision outputs flowing of (at 1, 0.1,least through 0.01, 1 percent) and the 0.001v. dividerThe 1:watt output string resistors voltages is held R3 are delivered by a voltage divider r-I rzt O RM4Z,currentanyduebyconstant battery toselected the oris by flatnesssupplied equivalent)B2. the value Q12N2712 of functionsby ofits and the basecollectorsilicon is1.4v setcurrent. as transistor mercurybya current constant means In -vsthisbattery,(Q1) of -current -voltage thecircuit and 10,000 BI is regulator(Mallorydeliveredcurvethe -ohm base for 148calibratortogetheritswirewound voltage with highly verypotentiometer, the nearlystabilitystable. to of R2.the the endA silicon mercury of life transistor, batteryand this makesmaintains feature, the 149 The instrument is initially calibrated in the following 5.24-SENSITIVE ABSORPTION WAVEMETER mannermeter.switch(VTVMmanner:(4) Set (S3) (5) foror (1)potentiometer TVM) toRemove1 Connectits-volt 1 to-volt at the the anposition. R2DC meter.DCaccurate, foroutput output an (3) With exact terminals.Close electronic terminals, R2 1 on -volt and -off (2) DCdeflection theS3switch Set setvoltagevoltmeter the S1in range -S2.thisof of the whichcouplingdinaryorconventional RF powerneitherabsorption to the oscillator,manner transmitter. wavemeter. to check It istheHence, frequencyThe wavemeter circuit shown in Fig. 5-25 the sensitivity of the field -strength meter but it is more sensitive than the or- useful in all applications in it does not need close of a transmitter is used in the usedpotentiometerbatterycalibrator to vary B2B2, will can the1 R2dropma. outputdrop and Whenfrom from calibrated,voltage lv desired,3v only smoothlyto to1.5vthis 0.975v.if Thepotentiometeranda between dial maximumthe is output attachedzero mayanddrain of thebeto from battery B1 is 77 u a and from Tablevariable(Section(Sections 5-1 capacitor5.4) for 5.6 coilnor and specifications.)the (C1) 5.7) oscillating and are aneeded. suitable featureThe RF plug-inTuning signal is accomplished by means of the ofdip a oscillator100-pf midget coil (L1).is (See rectifiedDC is by applied 0.001v.isresistancemaximum 5.23-ELECTRONIC100K for which value lv, 10K may selected for be THERMOMETER 0.1v,connected by 1Kswitch for to 0.01v, S3.the DCThe and output minimum 100 terminalsohms load for asgermanium lowquiescent,milliammetercurrentbase to bias be is diode readzeroamplifiedto the -signalon(M1). D1, 2N2712 the and by 0-1Nocollector the zeroma transistorresulting scale -set (less positive and silicon transistor(Q1). The basecurrent of the transistor is too is required,than 1 1.1a). Ci'sdeflects dial the 0-1 DC since the g.,thermistor,atemperatureallows insideworkbench the a furnace temperatureR1 indicatoror (Fenwal instrument or refrigerator, at sensorType another panel). GB42JM1, to locationbe Theor placed out sensorFig. orof(e. 5-24 atequivalent, doors) g., isone a indoorsis 15,000 locationa and useful which or-ohm on(e.temperature -measuring circuit which the R1 peraturetransistordropmistoracts asacross anda temperatureacting (Q1).potentiometerR2 is appliedAndupon -sensitivethis the as R2 DCbiasthermistor. in base series.isresistor. proportional biasDirect The toThe the resulting currentresulting 2N2712 to the voltagefrom silicon tem-base battery B1 flows through the ther- THERMISTOR scalecurrentarrangement,milliammeter (less isof amplified thethan transistor 1 u a).by the is tootransistor low to and be readdeflectsInitial on calibrationthethe 0-1 maDC is achieved by exposing the thermistor since(M1). There the quiescent, is no need zero -signal for a collectorzero -set potentiometerandthermistorTheto(determined notingrest of thesuccessivelythe R2 corresponding scale byfor anexact then accurate at full-scalemay various deflection. be thermometer), calibrated deflectionlowerthe Withdesired -temperature by R2of stabilizingthen metermaximumadjusted adjusting Mi.steps forthe temperature to be indicated voltThe(slightlya150 1 circuitbattery ma deflection underdraws (B1). oneapproximately at -tenth 350 degrees of full 1.1 scale) maF, a maximum deflection indicates from 0of degrees 0.085 the 6 ma- F. Fig. 5-24. Electronic thermometer. 151 oLO in .4- c c00 0 0 0 0 l0cr . . . . I L..)p C LOco Cf N 0 1'.4 Cr) LC) L') C...1 O Fig. 5-25. Sensitive absorption wavemeter. COcr maximumRFmay5.25-AF signal be ofgenerator calibratedWATTMETER 1 ma from loosely to the read 11/2 coupled directly -volt penlight to in Li. MHz The cell with circuit (B1). the draws aid of a an resistor,underaudiometer withtest-frequency Ri istwo (Dale dissipated ranges Typepower : 0-5 inRH-50, froma w 50 and -watt, anor 0-50 amplifierequivalent). 50w. -ohm,InFig. this or5-26 1 instrumentTheother percent shows resulting device load the circuit of an audio -frequency watt- allowvoltageActually,outputAF(Q1) voltage the ofand across theM1 circuit theis diodes isamplified outputloadan to electronic deflectsberesistor is standardizedrectifiedby the theACRi. 2N4868 0-50 byvoltmeterPotentiometers diodes DCon field-effect themicroammeter, D1monitoring 5- and and R2 D2. transistor50 and the The-watt M1. R3AF DC as singleranges, -pole, respectively. 2 -position, The nonshorting, ranges are rotary selectedThe selector instrument by switchmeans is(S1) of initially a . calibrated in the following in0 0 0 0 0 .4- M N ri 00 CC manner: (1) Set range switch Si to its 5 -watt position. (2) Is- tO t --I inputRMSClose signalterminals.on -off (any switch frequency(4) S2.Set (3)potentiometer between Apply an100 accurately and R2 1000 for an Hz)known exact to the 15.8v full- AF 0U) .4- .4- CO00 Cr) 0.1Cs.1 O n .4- 0 C N 152deflection,meterscale deflectionscale. and (5) mark Reduce of thismeter pointthe Ml, voltage 4 and w. (6)mark to Repeat12.2v, this point notingat the 5 variousthe w onmeter the 4.43 0. 153 tovoltages its 50-w shown position. in Table (8) Change B in Fig. the 5-26. input (7) -signal Set range voltage switch to 50v Si C)cD tc1 scaleshownrecordReduceofRMS, meter should adjustinthis the Ml,Table pointvoltage potentiometerandcoincide A as markin to40 Fig. 44.7v, withw.this 5-26. (10) R3 pointthose noting forAllRepeat 50 ofanof the wtheexact aton meter points0-5the the full-scale variouswatt meter deflection, on scale.this scale. defleconvoltages 0-50 (11) and (9) w + markingMake(The a voltage theseparate scale scale in0-50 voltage, should voltage withcoincide calibration Si set with to its the 50-wof originalthe position. meter, 0-50 ON N microampere scale of the meter.) 0C,1 0 C\J0 -NG I or other device under test will be some valueIn other many than tests, 50 theohms. output impedance (Zo) of the amplifier 0 0Csi cs.1 04 CV 0 -cp O WhenZo rated this isto the withstand case, repla& the expected RI with power.a resistor The Rx power equals in- 0 1 (.-3 (...) 0 LO Rxdicated when by Si the is meterin its 50must -watt then position, be multiplied or by by5 divided 50 divided by Rxby O wC -D CO (-3 0 5.26-TUNEDmaximumwhen Si is frominAF its ANALYZER the5 -watt 9 -volt position. battery The (B1). circuit draws 0.5 ma Lc) C P2 thecircuitarrangement 90-degree usually has phaseemployed: several shift advantages(1)to beA singleobtained overcontrol at theany (R4) simple frequency permits RC II Cr)1.1.4 "iii 0. settingbetween(3) The of 20 R4.outputs Hz (4) and Ahave 20 common kHz. a constant (2) ground No rangeamplitude, is providedswitching regardless between is required. of the the r a) UO0. circleinputoffers(6) Employing anddiameter) virtually the two isa no outputs.2N3823continuously load to field-effect(5) the The variablestandard gain transistor (and (potentiometer-frequency accordingly (Q1), source.the R1).circuit the 0,3'6' oscilloscopeamplitudesclosely matched then must .will be bekept very as shortnearly as equal. possibleIn this Connections tocircuit, prevent 1000 to stray the -ohm resistors R2 and R3 must be The horizontal and vertical output -signal 4(500 besetpickup. setfor for equal At the any horizontalsmoothest frequency circle;and (with vertical itsthe tuning oscilloscope gain), is reasonablyrheostat gain R4controls sharp. must a) circleThe maximum flattening isinput 1.5v -signal RMS and amplitude the corresponding before the maximum onset of CC U L approximatelyno-load output -signal1.6 ma amplitude from the 6is -volt1v RMS. battery The (B1). circuit draws UT .m0 uj(7.7)

o II' 160 161 Power Supply Applications Chapter 6 componentsandmodelsinTransistors this powercircuit chapter and -supply arecomponentmay from areemployed vary accessories.thosenamed somewhat characteristics. obtained in manufacturers various All due operatingin types totests individual Where of withare constants listed, the transistor author's these power supplies particular given resistanceswherethecircuit.appearcomponents specified shown Into all be are other(or electricalnecessary otherwise in their instances,ohms exact characteristics toandon the equivalents,however,the capacitances proper diagram performance whenor in in theobtainable) of the any componentmay be used. having Except microfarads; text, all 3.12,haveOtherresistors6.1-VARIABLE 4.10,possible circuits, 4.16, are use one-half5.17, described in DC powerand POWER 5.18.watt; insupplies earlier and SUPPLY capacitors arechapters, found whichin are Sections 25 DCWV. might also 2.7, resistoremploysgear.powering Its in maximuma transistorized series2N1482 with DCsilicon the outputequipment DC power output is 50v, transistor and of 400Fig. aother solid-state ma.6-1 as low Thea variable-voltage circuit is a variable -output DC supply suitable for power 54collectorrheostat,variedsupply D 3988, (T1by R1-emitter or-D1adjustment (Clarostat equivalent). -D2 resistance -C1). Type ofDiodes When the 43C2,is varied Di Ql's andor DC equivalent),accordingly. TransformerD2 base are 1N3544, -bias the Ti current isinternal 600 a 140v is to 40-0-40v, 1.2 light -duty 50K wirewound -amp unit (Knight controlelectrolytic.silicon162 rectifiers.a high The output Filteradvantage current capacitor ofwith this C1 a lightcircuit is a 100-mfd,-duty lies rheostat. in its150 ability DCWV to ma 163 Fig.units6.2-DC 6-2 in VOLTAGElowshows -voltage, a shunt REGULATOR voltage-type regulator -regulated (Shunt circuit,Power DC Type) so transistors called because function very well as automatic control power supplies. 6.3-VOLTAGEshownwithregulator the in powered describedFig. 6-3 thenequipment. in the is precedingmore TheIn some applications, the shunting REGULATOR (Series desirable. A 2N1070 silicon seriessection -regulator is incompatibleType) circuiteffect of the voltage variableregulationtheis(depending transistor 28 resistor, toprovided. upon shuntsconnected the thelevel inDC of series theoutput. unregulated with The a 10 maximumHEP -ohm, DC input:247 10 -wattNPN 40-50v) power transistor (Q1) acts as 30v, 500 ma. Approximately 2 percent voltage output a powerSincediode,ofthe Q1 power thisarisesD1 (TRWbiassupply from is Semiconductorsconstant, theand constant the output the voltageoperating Type dropPD6001, point across or transistor functions as a varible resistor in series terminals. The DC base bias of the transistor equivalent).the 3v zener with resistorbasecollectorfixedcomprised -bias resistor (R2) -emitter current ofin (R1) theseries. resistancewhich 1N5361Ato form If flows the anof voltage zener into theoutput transistorQ1 diode at fromvoltage the (D1) output ais voltage varieddivider. and terminals a dividerby47 The DC-ohm is wirewoundzener-currentteristic,fixed;current and the to because DCrheostatthe flow requiredoutput of through (R3) the remains level is setdiode for constant.to the limit D1,The 10,000 -ohm wirewound rheostat (R2) flatness of the collector charac- desired regulated output - theand transistor the 1000 base -ohmis set initially for therebycurrentitsrises, zener from loweringreduces point whatever is reached;the outputcause,shunting the voltage.the resulting resistancediode The conducts increase reverse of the heavilyof also transistor, Q1's is aftertrue.base uponcurrent the level. unregulated The maximum regulated DC input: 40-55v) is 50v, 1 amp. R1 is a HEAT SINK DC output (depending The net result is stabilization of the output voltage. RI 10R1 Q1 2N1070 10 D1 1N5361A 0 UNREGULATED Q1 REGULATED DC OUTPUT 1. 0 10K R3 1K REGULATED 0 DC INPUT HEP 247 (28-30V, 500 MA) 0 0UNREGULATED DC INPUT 01R2 (50V,MAX.) 1A, DC OUTPUT - 0 R2 S 47 DlagNPD 6001 164 Fig. 6-2. DC voltage regulator (shunt type). Fig. 6-3. DC voltage regulator (series type). 165 1-4rn

1 6.3 R1 400 K

S1

ON -OFF 2N190 Cl 0.005 C2=0.1 C3.7.0.1

B1 1.5V

D1 DC OUTPUT o - + 14 1N34A LOAD Fig. 6-4. DC -to -DC inverter (low voltage). RL

1N4003 Q1 Cl D1 C2 10 T1 S1 1.0 ON -OFF HEP 230 R1,) 50K 6.3 1N4003 D2 DC OUTPUT OUTPUT (175V) CONTROL

B1 6V C3 10 R2 300

Fig. 6-5. DC -to -DC inverter (medium voltage). may10 -ohm, have 10 -watt to be increased or decreased, depending upon in-resistor. The maximum value of rheostat R2 dividualdesigned6.4-DC-TO-DC transistor, to step INVERTER updiode, the voltageand (Low DC input-Voltage)Fig. voltage. 6-4 shows a simple Kundert-type of a 1.5v cell to 10 volts. A inverter circuit arefrequencycellhighlysmall, supplied (even lowportable a oscillator. -currentpenlightby a transistorized6.3v, cellunit 0.6AFeedback, when of this theequipment sorttuning, service Inperiod this circuit, a 2N190 transistor (Q1) serves as a filament transformer, Ti (Triad F - is handy for operating and voltage step-upfrom a single dry is short). low - co(NI4+1 correctly,13X, or equivalent). for oscillation. This This inverter transformer must be polarized will develop 10 volts DC The current drain 11111111111111z isacross 6.5-DC-TO-DC9 ma a from10,000 the -ohm 1.5 INVERTER load-volt (i.e., battery (Mediumi ma (B1). output). -Voltage)The inverter circuit shown in Fig. 6-5 delivers a maximum I- employsDCisThetransformeroscillator. outputapplied stepped a of toHEPThe 175 -upa(T1) voltage center volts230AC supplies output powerwhen -tappeddoubler deliveredpoweredthe transistor 6.3v(D1 tapped -D2winding fromby coiL-C2 the a -C3).of115v 6for a smallthis winding in a Hartley -type -volt battery. It oscillator. filament of Ti miniaturemaximummfd,(Triad 150 F 200v -14X, DCWV drain silicon or is equivalent).electrolytics. 80 rectifiers. ma and Capacitors Diodesthe With 50,000 aTiD1 6v C2is and -ohmbatterya and 6.3v D2 C3wirewound are(center are 10- -tapped), 1.2A filament transformer (B1), the and 1751N4003 volts.rheostatandtoR2 1.5 withR1 (R1)volts. will a 20 variesvary The-ohm, the maximum the 1no-load -wattno-load resistor, DCbattery DC output output batterydrain betweenIf R1 betweenthen B1 is may replaced60 and2 be with a 200 -ohm wirewound rheostat will be 100 ma, 80reduced volts. and flashlightwill6.6-DC-TO-DC step up cells the 3in volts INVERTERseries) from to a1000 battery. (High volts. Voltage)(e.g., AlthoughFig. 2 Size6-6 shows-C or the circuit of a small -sized inverter which the output Size -D 168 aspowercurrent Geiger supply is counters, low of (25this insulationmicroamperes),type is useful testers, aand miniature, portable in a number of places, such flashtube circuits. 169 O O Fig. 6-7. DC supply for tunnel diodes. providedtransistor.frequencyof(Microtran Ti must by Theis a beapproximatelyspecial 8051, feedback polarized or miniature equivalent). and correctly, 400voltage high Hz) The -voltage for step-up employingtwoThe oscillation. low circuittransformer, functions -voltage a is 2N414The actually windings are T1high a blocking oscillator (operating mahighestwirewoundoutput(Sprague(Di) from voltageand voltage the filtered rheostat 310TM-P10, -voltis output. rectified by battery(RI) the The is by0.1-mfd,or set(B1). circuit theequivalent). for 1N3283, reliable 1000vdraws 1500v tubularoscillation approximatelyThe 50,000silicon capacitor, and diode -ohm the70 Cl 6.7-DCvoltagegood regulation dividerSUPPLY operated FORand lowTUNNEL from output batteries DIODES resistance.Tunnel or other diodes Anpower ordinary require supply a low -voltage DC supply having desirednotcapable170 "stiff" ofcharacteristics enough delivering for correctthe required operation millivolts of Fig.the tunneloutput 6-7 shows diode.usually the is circuit of a DC supply which has the for tunnel -diode powering. This 171 tinuouslyarrangementtronics,(see Rufus Januaryvariable is P. based Turner, 1962, (by upon adjustment p."TD 72).a design Power The originatedDCof Supply," output output bycontrolvoltagePopular the author R1)is Elec- con- HEPresistorohms.between 230 R3 10 power andand the500 transistor internal millivolts, incollector series. and the The-emitter outputThe transistor outputresistance resistance portion circuit of is the consists of a voltage divider formed by of10 10,000divider,ofthe the divider transistor.-ohm by theresistance wirewound 1.5 Output-volt is batteryvaried by(B2). changingAt any the base base -current level (selected by adjusting the power is supplied, through the R1), the pentode -like current insurescurrentaccordingly,collector a isconstant suppliedcharacteristic a constant current by a 1.4 ofthroughoutput -volt the mercurytransistor voltage. output battery, resistor Becauseis B1 R3 (Mallorythe base rheostat, very flat. This and, 0InO RM1,6.8-CONSTANT-CURRENTstability, or equivalent), both R2 and R3 are ADAPTER 1 -watt resistors. (Low Level) it too is constant. For maximum 0etN ventionalautomaticvoltageremains constantor DC adapter in power the in may loadthe supply. facebe resistance. connected of wide variations Forto Somethe this output electronic inpurpose, the of applied a con- processesan require direct current which 9 light -duty use (output currents up to 50 ma).Fig. In 6-8 this shows circuit, the the circuit of a constant -current adapter for powertransistorinternal supply, collector is connected and -base that pathresistancein series serves with pathas thethe of current outputthe 2N130A -regulatingof the PNP DC OLI) loadcurrentcharacteristicelement. resistance. steady, That in inis, thespite the common flatnessof variations -baseof the in circuit thecollector applied holds volt-ampere voltage the output and I - B1,disadvantageThebiaswirewound mustcommoncurrent be andslightlyrheostat -basethat accordingly the transistorhigher (R1). emitter thanThis determines connection current,the adjustment output Thethedrawn shown (collector) collector desiredsets from here the output current. batteryemitterhas the -current level is set by the 10,000 -ohm o O 172commonIn(collector)(transistor a common -base circuit basecurrent.-emitter current)is much Butcircuit, theflatter is muchhowever,collector than smaller that thecharacteristic of control thethan common- the current output of the 173 dissipationvoltageconstantemitter6.9-CONSTANT-CURRENT fromand -current of thus the 2N130A DCadapteraffords power transistorwillbetter supply ADAPTERhandle current is of 100 a40v maximum regulation.(Highmilliwatts. DC. Level)Maximum applied This transistorferencesamesimilarma. circuitMeter tobetween in the Fig. MIexplanationone 6-9, alsothe described which circuits has been appliesallows in is the changedthe current here,previous useThe of too.regulationto constanta accommodate section,2N1041 The up-current and powerto 250the adapter circuit shown in Fig. 6-9 is main dif- the dissipationmaymaximumappliedhigher be current. voltageextended dissipationfigure from is up not theto is exceeded. 3DC20 amperes, watts. power Operation supply asThis long constantof asof100v this DC.-current circuit Ws adapter will handle a maximum the 20 -watt a filteroftransistor6.10-ELECTRONIC a power choke. can -supply Andbe utilized whererectifier. FILTER to high smooth In "CHOKE"this currents way,out Thethe the (several ripple constanttransistor in the -current acts output like collector characteristic of a power hundred overmilliamperes)Afield.transistor piconventional -type --unlike filter are is involved,filter theformed choke chokes bya coil-hasconsiderable the is realized.two no50-mfd,Fig. troublesome Furthermore,reduction 6-10 150v shows capacitors magneticin howsize the the transistor may be used in this way. terminals.rippleDCtendsgiven(CI collector toandfluctuationslevel remain C2) of voltage. DCand constant, in basethe theAnd 2N1070 bias,unfiltered in it spiteis the this silicon oftransistor DCaction fluctuations applied transistor that collector smooths to in the (Q1).the DC currentappliedout Atinput the any powerarethepropriatelyis 501000 a 51 voltstransistor -ohm, andsetting 2 51 -watt -wattisampere. the50 unit.rheostatwatts.base Maximum The -bias (R2). maximum current. dissipationThe Thelimiting obtainableBias output isof resistor adjustedthe DC 2N1070current outputs (RI) by is set to the desired level by ap- 174 175 Receivers, Transmitters Chapter 7 scienceshirtself-containedWith pocketthe fiction birth at became ofsuperhetlast the came transistor, everyday receiver true. What fact.the small radioman's Today,had enough previously a receiver todream fit intobeen withof a & Accessories sevenplantedcapacity,increasingreceivers,and transistorantenna, the however,anduse. vacuum is stages, inBecause no transmitters bigger tubethe and oftransistor in includingitsthan transmitters. relatively also, a cigarette has the battery, notlowtransistor Nevertheless, completelypackage.power loudspeaker, has-handling Infound some sup- TV completelylowtwiceinexpensive -powered the retailsolid thattransmitters price.state. an experimenter So nobody (especially would couldPresently, CBbuild not units) duplicatesuch asomeare set now onejust transistorized atto radio receivers are so Fig. 7-1. Simple supplies (Chapter 6), broadcast receiver. other circuits sometransistor.andcircuitsdiversionsave transmitter money.of withthem and These which Themay education applications, circuits hobbyistbe to combined experiment. in are andsimple each entirely withstudent, of Herereceiver whichother practical. arehowever, circuits, employs severaland transmitterMoreover, describedwill receivera single find described3.6,communications(Chapter 3.7-3.9,7.1-SIMPLE in 1) earlierand and 3.13. powerBROADCASTsystems, chapters, may RECEIVER bewhich found might in Sections be useful 2.1-2.4, also 2.8, in models;givenearliertransistor in in your thisthis and chapter book,readings circuit to are form maycomponent those more vary obtained complicatedsomewhat characteristics inCurrent, tests due setups. of to voltage,the andindividual author's different signal amplitude, and frequency values antenna2N190tapor equivalent), used transistor(L1) here is toa whichflat, (Q1) ferrite as -strip Fig. 7-1 is a simple match the input circuit of the comesbroadcast equipped receiver with circuit a employing a the detector. The self-contained type (J. W. Miller transistorlow to the-impedance No. 2004, receivinghowever,forexactnamed proper equivalents, manufacturers locations. anyperformance component when Where are of obtainable) listed,the particularhaving circuit. these the appear Incomponents specified all otherto be instances,electricalnecessary (orfrom their antenna.groundsignalwithvariable this pickup.Strong, will antenna capacitor, be For nearbyrequired. when other C1) stations the is 540 may to stations,The an external tuningreceiver range is rotated (with afor 365-pf 1650 kHz. be picked up directly antenna and maximum capacitorscapacitancesoncharacteristics176 the diagram are in mayormicrofarads;25 in DCWV. be the used. text, Except resistorsAsideall resistances fromwhere are one-halfaudio shown are in amplifiers ohmsotherwisewatt, and equivalent).transformer T1, Headphones a 20,000 -to or-1000 an The circuit delivers an audio output at the secondary -ohmexternal unit (Argonne audio ARamplifier -104, or may 177 of ANT

Ll

Cl 365 PF 2N3823 TUNING O D1 ON -OFF S1

1N34A

C2 I- R1 + B1 -7-9V 10K R2 .i.470 C3 50 GAIN

0 GND

Fig. 7-2. Diode receiver with transister AF amplifier.

ANT 0

Ll D1 01

1N34A C7 R1 Cl C2 C3_ C4 2N190 2K 1.0 *-480 180 GAIN PF OF PF PF PF R4 1 02 3 =C6

0.002 22K S2 o S1 ON -OFF TUNING R2 6.3K C8 Bl-- 6V R3 1K 1-+50 T+

GND 0

Fig. 7-3. Step -tuned broadcast receiver.

ID mabe connected from the 3 to -volt the AFbattery output (B1). terminals. The circuit draws 1 T WhenitsAMPLIFIER7.2-DIODE audio a single output RECEIVER audio (even amplifier with WITH strong, stage TRANSISTOR nearbyis addedA tuned stations) to thediode AF detector, is detector low. makes a simple radio receiver. But detector.2N3823byphonehowever, a single operation. field-effect Thethe -stage outputself-contained audio transistor is boosted amplifier. for antenna sufficientlypractically The (L1) amplifierFig. zero isfor7-2 a loading strongflat,is employsa broadcast ferrite head-of the a- -band diode detector circuit followed impedanceequippedstripexternalismay rotatedtype be with(J.picked antenna of forW. athe maximumlowMiller up 1N34A -impedancedirectlyand No. ground diode signal2004, with tap(Di). willorthispickup. usedequivalent), antennaStrong,be here required.For to whennearbyother matchwhich Thethestations, stations the comes receiver tuning low an drawsrequiredpotentiometercapacitorrange 2.1 (with to ma complete(C2). 365-pf from(R1) High thewhich variable the 9 -impedance -volttransistor's is RF-bypassedcapacitor, battery magneticDC (B1). Ci)The circuit. byis diode 540 theheadphones Theto0.001-mfd load 1650 circuit resistor kHz. are is the 10,000 -ohm gain -control amplifier).receiver(both7.3-STEP-TUNED circuitssimilar In Fig. toconsist 7-3,the one however,BROADCAST of describeda diode tuning detector in RECEIVER theisThe not preceding and circuitcontinuous, transistor shownsection but AF in Fig. 7-3 represents a broadcast andminiatureselectedselectorin C3 each atswitch trimmer will. have (Si) a capacitorsmaximum allows any capacitance(Cl steps.oneto C5). of The fiveofTrimmers 480singledesired stations pf (Elmenco-pole, C1,stations to C2, be are pretuned by setting each of the 5 -position, nonshorting, rotary highestTrimmercapacitanceType(J. W.466, -frequency MillerCi or is equivalent),of set No.180 for one. 2004, pfthe (Elmenco lowestand or equivalent). C4 -frequency and Type C5 each Strong,463,The stations, haveself-contained or nearbyequivalent). a C5maximum for stations the antenna (Li) is a flat, ferrite -strip type external180ismay rotated be antenna picked for maximum upand directly ground signal with will thispickup. be antennarequired. For whenother thestations, receiver an 181 Cl I- - Ll C3 200 PF Cl 0LL O ANT 2 o. C2--365PF 0.002 C4 S1 "]CO LiLL o GND rrUNING .5'4 2N2712 ON -OFF + 'MX11 0 0 (1)114-.---14- 111 REGENERATION CONTROL R1 B161.1 - , tif) 1:. potentiometer (R1) which is RF-bypassedThe by diode the 0.001-mfd load resistor Fig. 7-5. Regenerative broadcast receiver. is the 2000 -ohm gain -control ct z1,1CO 1.0 numberselectordrawssupplycapacitor 2.1 DC of ma basesteps from bias may the to 6 bethe -volt provided 2N190 battery transistor by (B1). means While (Q1). of aadditionalThe 5 -station circuit (S1 -C1 (C6).-C2 -C3 -C4-05) Resistors R2 and R4 form a voltage divider to is shown here, any desired switch7.4-SELECTIVEsuch pointsdevices, and most trimmerBROADCAST diode capacitors. detectors RECEIVER sufferBecause from of poorthe low selec- -impedance loading effects common to broadcastcapacitorsubstitutingtivity, especially receiverband.tuned a bandpass Much atcircuit. employing the highsharper tuner Fig. -frequency such for 7-4tuning the showsa bandpassThecommon may end bandpass the beof theobtainedfilter.circuitsingle standard unit -coil/of byconsists a of two RF transformers: Ti and T3 (J. W. Miller No. 242-A) and a negative mutual kHz.variablecoupling For best capacitor coil, selectivity, T2 (C1(J. W. T1-C2) Millerand tunes T3 No. mustthis EL filterbe -56).connected from A 540dual exactly to 365-pf 1650 -CD l-CU e PI 182amplifieras shown: stage Follow employing the terminal a 2N3823 numbering field-effectThe shown diode transistorin detector Fig. 7-4. is transformer -coupled to an audio 990, J 183 (Q1). The coupling transformer, T4, is a miniature 5K -to -80K maunit7.5-REGENERATIVE from (Argonne the 9 AR-volt -158, battery orBROADCAST equivalent).(B1). Regeneration TheRECEIVER circuit increases the sensitivity of a simple radio draws 2.1 1 couplerequivalent).tennaarrangement,circuitreceiver. -stageemploying tunes Fig. With fromRFthe 7-5 transformer input a 540the 2N2712shows to 365-pfcoupler 1700 a silicon regenerative kHz.(J.variable (L1 W. Thetransistor-L2) Miller capacitorlow is broadcast a -turns No.TRF-type (C2)coil (L1) this (Q1). In this -receiver20-A, or an- _400$3 I( biasreverseormust oscillation be thepolarized connections is not correctly obtained to Li).for at The one-half-megohm rheostat (R1) controls the DC regeneration (if regenerationany setting of rheostat R1, base of fromrheostat,regeneration.7.6-ALL-WAVE the 6 -voltthe circuit batteryAt REGENERATIVEextremely will (B1). oscillate. low The-resistance RECEIVER maximum settings drain isof 2 thisof the transistor and accordingly the amount ma C approximatelyemploying plug-in 100 MHz.coils (Li) The whichoscillator tunes Fig.circuit from 7-6 is 1.1 showsa MHz the to circuit of a regenerative receiver,Colpitts- C,Jcr 0-L.- perienceddividual1.1-2.5,inSixtype Table plug-in circuit 2.5-5, 5-2,transistors in coilsbased reachingChapter 5-11.5, may upon and 5,be10-25, the whicha woundlayouts, 2N3819top 20-45, ofwill according the field-effect and highest 40-100 to frequencyinstructions transistorMHz. (With band.) in- some difficultycover may the following be ex- bands: given(Q1). controldetuningpermits thethe effects. amountpeaking The of ofgate regeneration. a signalbias -control and Theminimizing rheostatIn 5K this (R1)circuit, of the 50-pf midget variable -to -10K couplingcapacitor (C3) serves to antenna AF C fromconnectedoutput.transformer, the Headphones 6 to-volt Tithe (Argonne batteryAF output or (B1).an AR externalterminals. -155, or audio Theequivalent) circuitamplifier delivers draws 1 ma may be - C 7.7-AUTODYNE CONVERTER .000 WS F - broadcast -band service. This unit, employingFig. 7-7 shows the circuit of an autodyne converter for a 2N2712 silicon 184superhet.andtransistor thus (Q1),constitutes performs the both entire oscillator front endand mixerof functions a broadcast fir 000 (> 0 185 0.5M RI Ql 2N2712 L_U- -4cn DC uA0-50 --1000 Y fn 0 0 DC SIGNALINPUT DC FROMSUPPLY 6V 4 z Fig. 7-9. Meter -type tuning indicator. R1 1K 2N2712 vi(2v,wiA) O 0O DC INPUTSIGNAL DCFROM SUPPLY 4.5V 4.90.94S29 Q.90 0 Q.IL 1 186 Fig. 7-10. Light -bulb -type tuning indicator. 187 In Fig. 7-7, T1 is a broadcast -band oscillator coil (J. W. Q1 oscillationcapacitorMiller No. (C2).(follow 2023, This orthe equivalent) terminalcoil must numbering tunedbe polarized by shown a 365-pf correctly in Fig. variable 7-7). for U 2 22 TUNING C3 100PF Ll frequencycapacitorThetransistor series (Elmenco padder output-type IF (Cl)(455 Typetransformer, is kHz) a308, miniature isor T2deliveredequivalent). (J. 1200-pf W. Miller by Intermediatemica a miniature, No. trimmer 2031, - or XT AL C2 0.002 RFC1 equivalent).(B1).7.8-SUN-POWERED The circuit BROADCASTdraws 2.1 ma from RECEIVER the 6 -volt battery R1 100 K Ml 2.5MH to the one described earlier in Section 7.1,The except broadcast that the -receiver Fig. circuit shown in Fig. 7-8 is similar 100 R2 C 0.002 0-50 DC MA DC silicon7-8inS1M, circuitSection solaror equivalent).is 7.1 cells,powered applies PC1-PC5 Otherwise,by here, a solar as(International well. batterythe circuitThe consisting solarexplanationRectifier cells of Typeare five given connected in series (red positive pigtail KEY t 0 o- SUPPLY (24V)50MA of deliverstheone corresponding cell to black negativeR and B labelspigtail in of Fig. the 7-8). other, The as combinationshown by approximately 2.75v DC in bright sunlight. Cl 01 Fig. 7-11. CW transmitter. C3 E--s----if C5 fluctuatingchargeThe(Professional 100-mfd and sunlight.keeps electrolytic solar the 2N190batteries capacitor collector will deliver (C2)voltage higherholds fairly aDC goodsteady voltage.) DC in 100 PF U 222 RFC1 ,r71.01O 2.5'1H 100 PF Ll 7.9-METER-TYPE TUNING INDICATOR C2,pIL 0.002 T100 PF proportionalansecondbe inexpensiveoperated detector to from signal 1 -inch output,any strength point-diameter AGC, inis aobtainable. 0-50receiver etc.) DCFig. microammeter.circuit 7-9The shows indicator (such the as iscircuit the of a tuning indicator which may where a DC level RF INPUT 6 (f) 50KR1 DCUNINGt_ge MA0-50 C 4 ri RF OUTPUT (2f) 0 plifier.ua)collector to No deflect zero current -setthe ofmeter.is thisneeded, silicon A DC since inputtransistor the signal quiescentThe is tooof 2N2712 1.2v low(zero at(less -signal)transistor2 u.a than will 1 (Q1) acts as a high -gain DC am- S1 ON -OFF SUPPLY DC acreasedeflect maximum7.10-LIGHT-BULB-TYPE the meter resistance of 50Ml ua to from tofull R1 thescale. proportionately. 6TUNING -volt For DC higher INDICATORsupply. inputThe circuit signals, draws in- I - (2")50MA 188indicating device here is a 2v, Another tuning -indicator circuit is shown in Fig. 7-10. The 60 ma pilot lamp (V1). Fig. 7-12. Frequency doubler. 189 zerolamp.Maximum -set (lamp signal extinguisher) is indicated is by needed, the Thebrightest since 2N2712 the glow quiescenttransistor of the (Q1) acts as a DC amplifier. No + 10CC1 01 2N3823 atitslow (zero 1maximum ma(less -signal)will than produceresistance 1 collector;Ja) tomaximum oflight 1000current the ohms, brilliance.lamp. of this a WithDC silicon Theinput rheostat lamp transistorsignal R1goes of set 1.5v isout to too T1 maximumwhen7.11-CW the of signal 60 TRANSMITTER ma fromdrops the to 41/2 0.7 -volt volt. DC The supply. circuit draws a PC1 200 II 03. 2K P11.11 GAIN ON -OFF S1 watt,type(Q1). CW it canWhile transmitter, be theeffective RF employingpower when output communication a U222 of thisFig. field-effect transmitter 7-11 conditions shows transistor is theonly arecircuit 0.6 of a simple crystal oscillator - UNUSED 470 R2 C2 50 B1. -.9V + capacitormanner.favorable.transmitter The C3 combinationat "coil" the crystal chosen L1 frequency. to-L2 resonate is a commercial (IfThe withdesired, circuit 100-pf low the is -powerreadervariable tuned and operated in the conventional in Fig. 7-13. Light -beam receiver. maydipamateur wind of the radiohis 0-50 own handbooks.)DC coils milliammeter according (M1), to instructions Afterthe circuit being then foundtuned may to crystalbe resonance, as indicated by the KEY 28vFortainedDCloaded12.5v DC.example,power withby DC, theinput heavier and Type antenna ofType 2N56441.2and to SRD54117watt. more 50 (Motorola) ma.Higher expensive At (Solitron 24 output volts,will RF deliverDevices)powerpower this represents maytransistors.12 60 watts bewatts ob- ata at 7.12 -FREQUENCY DOUBLER The circuit in Fig. 7-12 is a frequency doubler. Multipliers B1.= 4.5V R1 01 2N190 e -C1-1)- circuitoutputmitters.of this employs frequency typeFor doubling, are a commonU222 2f. (Thethe field-effect input L1in the -C4 frequency exciter transistortank is f sections tunedis operatedconverted to of2f.) attrans- toThis24v, an 2K Cl 7.0.025 0.25 C2 is50 transmittertuned ma, and and its operated RFcoil output chosen in is the approximately to conventional resonate Thewith 0.6 manner. watt.tank 100-pf Theinductor variable circuit (L1) is a commercial, low -power R2 inreadercapacitor 190amateur may C4 radiowind at twicehandbooks.)his own the coil input Afteraccording frequency. being to tuned instructions (If todesired, frequency found the Fig. 7-14. Code -practice oscillator. 27K 191 ma.the2f, ascircuit At indicated 24v, then this bymay represents the be dip loaded of thea DCby 0-50 the power DCsucceeding milliammeter input of stage 1.Z (M1),watt.to 50 expensiveHigher7.13-LIGHT-BEAM power RF outputpower maytransistors RECEIVER be obtained (see Section withFig. heavier 7-13 7.11). is andthe circuit more of a simple receiver for use in voice - coupledfrequencyresultingthemodulated(International modulated (by DCas light 200 the output light-beambeam,-to Rectifier -2K beamof andcommunications. transformer the the strikesType cell AF is componentS1M, aT1:modulated silicon ArgonneIn or this equivalent). solarof arrangement,thisat AR thecell, output -123, same PCi Theoris maoperatedmanyeffectequivalent) from transistorinstances, fromthe to 9 anthe-volt (Q1). audio anoutput battery external amplifier of (B1).this audio circuit. employing amplifier TheWhile circuita 2N3823 headphones also draws may field- 2.1 be are shown here, and are adequate in headphones.which7.14-CODE-PRACTICE gives Thea good Colpitts-type signal OSCILLATOR circuit,Fig. employing 7-14 shows a 2N190 the circuit of a code -practice oscillator in high -impedance magnetic and7500.025tunedtransistor Hz.C2 mfdcircuit simultaneously,The (Q1),and frequencyand C2 usesthe as 0.25usual the may and mfd,headphones split be may increasedthe -capacitor befrequency decreasedWith as by theleg decreasinga is pairC1inductor approximatelyby -C2.of increasing Trimm both of the Cl2000 -ohm headphones and with Cl as theseTheohmtiometerofhowever, frequency circuit wirewound Ri. the draws Should ratiois provided rheostat3of controlma C2 from to by inClof the adjustmentseriesvolumeshould 4.5 with-volt be be 10desired, thebatteryof to 2000 2N1901. Some insert(B1). -ohm collector. variationa poten-5000 - capacitances simultaneously. At any frequency, 192 Other CO TAB BOOKS of Interest HOBBY & EXPERIMENT BASIC TECHNOLOGY 542 -TRANSISTOR PROJECTS FOR HOBBY- 538 - COMPUTER CIRCUITS & HOW THEY $4.95 ISTS & STUDENTS. Steckler. 192 pages, 140 WORK. Byron Wels. 192 pages. 134 illus. illus. $4.95 530 - BASIC ELECTRONICS PROBLEMS 537 - 125 ONE -TRANSISTOR PROJECTS. SOLVED. D.A. Smith. 192 pages, 100 ill us $4.95 Rufus Turner. 192 pages, 125 illus. $3.95 528 - PULSE & SWITCHING CIRCUITS. 524 - 104 EASY PROJECTS FOR THE Harvey Swearer. 256 pages, 200 illus. $5.95 ELECTRONICS GADGETEER. Robert M. 510 - HOW TO READ ELECTRONIC CIRCUIT Brown. 160 pages, 104 illus. $3.95 DIAGRAMS. Brown & Lawrence. 192 pages, plus 487 - 64 HOBBY PROJECTS FOR HOME S. 64 -page schematic foldout section, 140 illus.$4.95 CAR. Brown & Olsen. 192 pages, 111 illus. $4.95 112- LEARN ELECTRONICS BY BUILDING. 486 - 104 SIMPLE ONE -TUBE PROJECTS. John Schroeder. 208 pages, 209 illus. $4.95 Robert M. Brown. 192 pages, 104 illus. $3.95 111 - BASIC TRANSISTOR COURSE. Paul R. 464 -ELECTRONIC HOBBYIST'S IC PROJECT Ken ian. 224 pages, 176 illus. $4.95 HANDBOOK. Robert M. Brown. 160 pages $3.95 105 - BASIC TV COURSE. George Kravitz. 224 462- 104 EASY TRANSISTOR PROJECTS YOU pages, 137 illus. $5.95 CAN BUILD. Robert M. Brown. 224 pages, 104 104- BASIC RADIO COURSE. John T. Frye. 224 $4.95 illus. $4.95 pages, 131 illus. 135 - RADIO CONTROL MANUAL. Edward L. G100 - BASIC MATH COURSE FOR ELEC- Safford. 192 pages, 147 illus. $4.95 TRONICS. Jacobwitz. 160 pages, 89 illus. $4.95 129 - SKILL -BUILDING TRANSISTOR 99 - INDUSTRIAL ELECTRONICS MADE PROJECTS& EXPERIMENTS. Lou Garner. 192 EASY. Tom Jaski. 288 pages, 239 illus. $5.95 pages, 128 illus. 54.95 SOLID STATE TECHNOLOGY 122 - ADVANCED RADIO CONTROL. Edward L. Safford, Jr. 192 pages, 174 illus. $4.95 513 - UNDERSTANDING SOLID-STATE 93 -RADIO CONTROL HANDBOOK: New 3rd CIRCUITS. Crowhurst. 192 pages, 150 illus. $4.95 Edition. Howard McEntee. 320 pages, 240 ill. $6.95 501 - WORKING WITH SEMICONDUCTORS. 89 - TRANSISTOk PROJECTS. Radio Elec A. C. Saunders. 224 pages, 185 illus. $4.95 tronics Staff. 160 pages, 123 illus. $2.95 493 - SEMICONDUCTORS FROM A TO Z. 83- FUN WITH ELECTRICITY. Tom Kennedy, Phillip Dahlen. 288 pages, 300 illus. $5.95 Jr. 128 pages, 95 illus. $2.95 470 - TRANSISTOR CIRCUIT GUIDEBOOK. 74 - MODEL RADIO CONTROL. Edward L. Byron Wels. 224 pages, 104 illus. $4.95 Safford, Jr. 192 pages, 210 illus. 116 - GETTING STARTED WITH TRAN- 70 - ELECTRONIC PUZZLES & GAMES.$495 SISTORS. Lou Garner. 160 pages, 89 illus. $3.95 Matthew Mandl. 128 pages, 72 illus. 53.95 94 - TRANSISTORS. Radio Electronics Staff. 96 69- ELECTRONIC HOBBYIST'S HANDBOOK. pages, 65 illus. $2.95 Rufus Turner. 160 pages, 118 illus. $2.95 75 - TRANSISTORS- THEORY & PRACTICE. Rufus Turner. 160 pages, 143 illus. $3.95 AMATEUR RADIO 63 - TRANSISTOR CIRCUITS. Rufus Turner. 160 pages, 146 illus. $3.95 543 - AMATEUR RADIO EXTRA -CLASS 61 - TRANSISTOR TECHNIQUES.Radio LICENSE STUDY GUIDE. 73 Magazine. 224 Electronics Staff. 96 pages, 78 illus. $2.50 pages, 162 illus. $4.95 527 - AMATEUR RADIO ADVANCED CLASS AUDIO & HI Fl STEREO LICENSE STUDY GUIDE. 73 Magazine.192 pages, 73 illus. $3.95 546 - ELECTRONIC MUSICAL INSTRU- 499- CB RADIO OPERATOR'S GUIDE. Brown MENTS. Crowhurst. 192 pages, 125 illus. $4.95 & Lawrence. 224 pages, 138 illus. 54.95 529 - HANDBOOK OF MAGNETIC RECOR- 469 - HAM RADIO INCENTIVE LICENSING DING. Finn Jorgensen. 224 pages, 90 illus. $4.95 GUIDE. Bert Simon. 160 pages, 314 Q & A, 35 534 - SERVICING MODERN HI-FI STEREO illus. $3.95 SYSTEMS. Norman Crowhurst. 224 pages, plus 468 - 104 HAM RADIO PROJECTS FOR schematic foldout section. 125 illus. $4.95 NOVICE & TECHNICIAN. BertSimon. 192 505 - INSTALLING & SERVICING HOME pages, 104 illus. $3.95 AUDIO SYSTEMS. Jack Hobbs. 256 pages, 150 460 - VHF HAM RADIO HANDBOOK. Edward illus. $5.95 G. MacKinnon. 176 pages, 100 illus. $3.95 497 - TAPE RECORDING FOR FUN 8. PROFIT. Walter Salm. 224 pages, 200 illus.$5.95 RADIO SERVICING 494 - AUDIO SYSTEMS HANDBOOK. Norman 504 - HOW TO FIX TRANSISTOR RADIOS & Crowhurst. 192 pages, 125 illus. $4.95 PRINTED CIRCUITS. Leonard C.Lane. 256 120 - HI-FI TROUBLES. Herman Burstein. 160 pages, 150 illus. $4.95 pages, 130 illus. $4.95 429 - EASY WAY TO SERVICE RADIO 86 - INSTALLING HI-FI SYSTEMS. Marked & RECEIVERS. Sands. 176 pages, 100 illus. $3.95 Stanton. 224 pages, 152 illus. $5.95 78- RAPID RADIO REPAIR. G. Warren Heath. 79 - DESIGNING AND BUILDING HI-FI 224 pages, 104 illus. 64.95 FURNITURE. Markel I. 224 pages, 195 it $4.95 76 - SERVICING TRANSISTOR RADIOS. 67 - ELEMENTS OF TAPE RECORDER Leonard D'Airo. 224 pages, 202 illus. $4.95 CIRCUITS. Burstein & Pollak. 224 pages, $4.95

®TAB BOOKS-Blue Ridge Summit, Pennsylvania 17214