PREFACE v28

1

Beam-Direction Marker Circuit for Scope

Gives Comet-Shaped Trace. Magnetically Deflected Oscilloscope Uses 21-

Inch Television Picture Tube. 281

31

2 31

3 32

4 35

6 35

7

ALARM CIRCUITS. Balanced-Capacitance Antenna Alarm Pro-

tects Barbed-Wire Fence. Comparator Circuit for Magnetic-Tape

Printer Sounds Alarm If Copy Deviates

from Master. Failure of Picture or Sound Carrier Trips TV

Transmitter Alarm Conelrad Alarm Is Triggered by Loss of Re-

ceiver A VC Voltage Crystal Transducers in Acoustic Chamber

Detect Breaks in Moving Film. Electronic Highway Scale Trips Alarm If

Moving Truck Is Overweight. Transistorized Crevasse Detector Uses A-F

Transmitters and Receivers.

368

3810

3910

12 40

13 43

14 44

15 44

18

4518

2047

20 49

21 51

QOMPUTER CONTROL CIRCUITS. ..

Transistorized Gate, Flip-Flop, Counter and

Shaper Circuits for Digital Computers. .

Read and Write Amplifier for Digital Data in

Tape Systems Dual Chopper-Stabilized Operational Ampli-

fier for Analog Computers. Simple Operational D-C Amplifier Is Basis of

Desk-Size Differential Analyzer. ...

Analog-Digital Converter Generates Pulse

Frequency Proportional to D-C Input Volt-

age. Direct-Coupled, Emitter-Coupled and Resis-

tance-Coupled High-Speed Flip-Flops ..

Transistorized Trigonometric Function Gen-

erator Provides Cosine of Input Voltage .

Precision Digital Delay Generator for Radar

and Sonar Calibration and Target simu-

lation Sine-Cosine Approximator for Radar Com-

puter Uses Diode Function Generator. .

Nine-Bit Word Generator Ghecks Digital

Computers at Pulse Rates up to 1 MC ..

Probability Computer Produces Output Pulse

When Noise Exceeds Reference Threshold .

Digital Comput~r Clock Circuits Use Ger-

manium Transistors Either at Saturation

orCutoff Triangular-Wave Generator and D-C Opera-

tional Amplifier Serve in Analog Multi-

plier Transistor Matrix Gives Simultaneous Binary

Addition and Multiplication. Combined D-C Amplifier and Chopper Am-

plifier Give High Zero Stability. Zero-Crossing Detector Aids Analysis of

Brain Waveforms. Transistorized Analog-Digital Converter Uses

Feedback Subtraction.

22 51

23 53

5724

AUDIO CONTROL CIRCUITS" .." "

Speech Rejector Differentiates between

Damped Speech and Undamped Music. .

Biased-Diode Squelch Circuit Mutes Mag-

netic-Tape Print-Through ." " .."

Speech-Music Discriminator Silences Radio

Loudspeaker During Commercials" " "

Automatic Speech Amplitude Control Pro-

vides Differentiation and Clipping" ". .

Automatic Fine Tuning Circuit Controls TV

Sound-to-Picture Ratio. " Heartbeats Are Made Audible by Frequency~

Modulating 1,OOO-CPS Oscillator" " " .

Burst-Modulated A-F Transmitter Controls

Tuned-Reed Induction Paging Receivers .

CATHODE-RAY CONTROL CIRCUITS" .

Ferrite Disk on Engine Shaft Generates Input

for Cathode-Ray Retation Analyzer " " .

Four- Thyratron Sawtooth Pulser PI:oduces

True Voltage-Curreht Curves on Scope. "

Electronic Shutter forf{V Kinescope Recorder

Passes Exactly 525 Lines. " .

Isoecho Contour in ~eather Radar Shows

Center of Thunderstorm. " Signal- Triggered Sweep Magnifies Pulse

Widths on Scope" ..." "

Synchronizer Feeds Transients to 12 Cathode-

Ray Tubes Having Different Base Lines .

~

26 57

COUNTING CIRCUITS. Transistorized Decade Counter Uses Cas-

caded Bistable Multivibrators

VII

CONTENTS

8857

59 8991

6001

6293

6495

6796

6796

6997

72 98

Batching Counter Actuates Solenoid at Prede-

termined Count and Resets Automatically.

Unijunction Transistors Simplify Design of

Bistable Stages for Ring Counter. ...

Reversible Binary Counter Determines Vari-

ations in PCM Pulse Intervals. ...~

Coincidence Detector Counts Missing Pulses

in Radar Magnetron Output. Automatic Bacteria Colony Counter Uses

Anticoincidence Circuits. Loudspeaker Serves ItS Microphone for Sim-

ple Shot and Blast Counter. Predetermined Counter and Gate Fire Flash-

lamps in Missile Test Lab. Four-Decade Decimal Counter Uses Beam-

Switching Tubes. Ring-of-l0 Counter Having Four ON Stages

Requires Only Three Feedback Resistors

PerStage Binary-Decimal Counter Uses Logical AND

Gates in Feedback Loop. 74 99

Level-Deviation Detector Locates Flaws in

Magnetic Tape. Recorded Tone Bursts Permit Dialing of 45

Taped Spot Announcements Automatic Stop Circuit for Tape Recorder .

Electrode Drive-Motor Servo for Spark Ma-

chining Auto Transmission Gear Contour Gage Con-

trols Automatic Bobber and Gear Sorter .

Four-Transistor Inverter Drives Two-Phase

Drag-Cup Servo Motor. Muscle Potentials of Patients Control Respi-

ration Rate of Iron Lung. Tracer Control Circuit Maintains Constant

Cutting Velocity for Milling Machine. .

Three-Feed Control System for Metal-Cut-

ting Band-Saw Carbon Dioxide Analyzer in Feedback Loop

Controls Valve Motor. Ei~ht Audio Tones Recorded on Magnetic

Tape Control Overhead Crane. Circuit Controls Vacuum Actuators of Bigh-

Speed Tape Transport.

76

MAGNETIC AMPLIFIER CIRCUITS76

76

78

79

81108

82100

83110

84112

84113

Transistor Magnetic Inverter Uses Differen-

iial Multivibrator for Signal or Power Con-

version. Magnetic-Amplifier Square-Law Circuits

Serve in Four-Quadrant Analog Multiplier .

Magnetic Amplifiers and Saturating Trans-

former Regulate D-C Power Supply. ..

Self-Balancing Magnetic Amplifier Drives

400-CPS Servo-Motor. Magnetic Servo Amplifier Drives Gyro Indi-

cator Magnetic Amplifiers Control Frequency and

Voltage of Reflex Klystron. Magnetic-Core Frequency Divider Controls

ITV Sync Generators. Half-Wave Magnetic Amplifier Drives Two-

Speed High-Impedance Servo-Motor. ..

Saturable-Core Transistor Oscillator Inte-

grates Gas Flow Data. Synchronously Switched Biased Diodes In-

crease Gain of Magnetic Amplifier. ..86

114

86MEt\SURING CIRCUITS 116

DIRECT-CURRENT AMPLIFIER

CIRCUITS , , , , , , , , , , ,

Feedback Increases Input Impedance ofTransistor D-C Amplifier " , , , , ,

D-C Amplifier for Voltmeters and Analog

Computers Has Infinite Input Impedance

and Infinite Voltage Range, , , , , ,

Wide-Band .Differential Amplifier for Null

Detection""",..",

Silicon-Diode Electronic Chopper Stabilizes

All-Triode D-C Amplifier, , , , , ,

Low-Drift Transistorized Differential D-C

Amplifier Uses Silicon Temperature-Com-

pensating Resistor, , , , , , ...

Junction- Transistor D-C Amplifier for Tran-

sistor Voltmeter , , ...

Differential Input Stage Improves Feedback

Stabilization of D-C Amplifier, Vibrating-Capacitor Modulator Changes D-C

Output of Differential Analyzer to A-C , .

Electronically .'ontrolled Chopper Boosts

Sensitivity of Infrared Detector. ., .

Twin- Triode Electronic Chopper Handles

High D-C I~ut Voltages, *

Feedback Throiigh Pentode Holds Cathode

Follower at Unity Gain. .., , ..

~lmp\~ Dl~~T~ntla\ D-C A.mp\\n~T l()T C()ntT()\

Systems Amplifies Difference Between Two

Signals, ..., ..., ., , . 87

1168~MACHINE CONTROL CIRCUITS. ...

Size Control Circuit for Automat~c Cylinder

Hone. ~ 117

D-C Error Voltage of Resistor-Checking

Wheatstone Bridge Is Amplified to Drive

Go-No-Go Meter. Circuit Delivers Pulse Width Proportional to

Time That Signal Is Between Specified

Voltage Levels.

...

CONTENTS

lfiO

llR

150

119JfiO

1201.~2

121153

METAL DETECTOR.CIRcUITS Proximity Control Responds to Any Metal

Near Pickup Coil. Magnetic Concentricity Gage Trips Flashtube

Trigger Circuit. Detector Traces Buried Cables Carrying 250-

CPS Signal. Tack Detector for Shoes Trips Alarm When

Probe Touches Metal. Inexpensive Metal Detector Locates Con-

cealed Conduits. Pipes and Ducts. ...122

154

1231.116

12.1'j

156125

1!>6

1261.~~

127 159

160127

,

MULTIVIBRATOR CIRCUITS. Two Multivibrators and Variable Delay Line

Generate Variable-Width Pulses. ...

A-C Tachometer Drives Multivibrator Cir-

cuits of Expanded-Scale Speed Indicator .

Multivibrator, Blocking Oscillator and

Counter Circuits Simulate Radar Targets .

Fast-Switching Multivibrator-Controlled Re-

lay Circuit Electronic Chopper Replaces Vibrator in

Television Modulation Indicator. ...

Simple Sweep Generator for Oscilloscopes Has

Range up to 500 KC. 11'\1

129

163129

130 163

131

163134

165

13.1) 167

137 lfi7

138

168140

169141

,

NUCLEONIC CIRCUITS. Transistorized Geiger-Muller Probe Traces

Radioisotopes in Oil Well. Time Interval Analyzer Uses Modified

Chronotron Circuits to Time Nuclear Par-

ticle Flights Transistorized Geiger Counter Has High-

Voltage Generator and Ratemeter ...

Cold-Cathode Count-Rate Circuits Monitor

Alpha Radiation. Eddy-Current Circuit Detects Hairline Flaws

inFineWire Time-of-Arrival Indicator Blows Fuse to

Stop Clock When Radioactive Fallout Ar-

rives. Transistorized Gamma-Radiation Monitor

Uses D-C/D-C Converter. Simple O-M Radiation Monitor and Re-

corder. .. 171142

172143

144

14,1)

Pulsed Eddy Currents Measure Thickness of

Metal Coating on Base Metal. Phase Comparator Locates Null as Float

Moves Core of Differential Transformer in

Liquid D.ensity Gage. Magnetic Quadrupole Is Probe of Magne-

tometer Using Servo Loop. Fast-Acting Nonlinear Feedback Stabilizes

Gain of Transistorized Pulse Amplifier. .

Ergmeter Uses Bolometer Bridge to Measure

Energy of Discharging Capacitor. ...

Automatic Range-Selecting Servo for Elec-

tronic Voltmeter Electronic Integrator-Amplifier Speeds Grad-

ing and Matching of Magnetic Cores. ..

Hot-Wire Thermal Bridge Is Voltage Stand-

ard for Expanded-Scale A-C Voltmeter. .

Bootstrapped-Collector Circuit for Starved

Transistor Has 500-Megohm Input Resist-

ance Differentiating Circuit Accurately Locates

Zero of A-C Voltage. Counter on Shaft of Servo-Driven Self-Bal-

ancing Potentiometer Gives Digital Pres-

entation for VTVM Tuned Voltmeter Measures First Four Har-

monics of Power-Line Frequency. ...

Meacham-Bridge Oscillator and Frequency

Detector Measure Ice Coating Thickness .

Admittance-Measuring Circuit Determines

Setting Time of Cement. Linear Potentiometer and Operational Am-

plifier Serve as Wide-Range Tachometer .

Capacitance Pickup on Angle-of-Attack Po-

tentiometer Boosts Accuracy. Schering Bridge and Phase-Sensitive Volt-

meters Sort Capacitors in Tolerance

Ranges. Portable Vibration Meter Uses Transistorized

Integrating Amplifier and Demodulator .

Automatic Waveform Detector Uses Time-

Sampling to Sort Ferrite Cores. Thickness of Nonferrous Metals Is Gaged

by Electromagnetic Absorption. Flutter and Wow Mete:t Measures Variations

in Tape Recorder Transport Speed. ..

Checking Insulation R$Sistance of Pressure-

Sensing Potentiometvs Second-Harmonic Flu~Gate Magnetometer

Serves as Steel Tubing Hardness Tester. .

Tester Checks Static and Dynamic Unbalance

of Dual-Triode Sections. Dual-Channel Doppler Radar Serves as Rate-

of-Climb Meter. Automatic Go-No-Go Comparator Makes 350

Checkout Measurements on Missile ---

OSCILLATOR CIRCUITS. Self-Quenching Superregenerative Oscillator

Produces Pulses of 500-CPS Tone. ...

Pulse Genetator Feeds Controlled-Duration

Signals to Two Channels. Pulse Modulator Gener~tes Uniform Pulses

for Widely Varying Load.147

ix

CONTENTS

175 200

176 202

204177

178 204

179 205

180 207

1 Rl 207

181

208

182

20~184

18., 210

186 212

187 212

188

2141~~

21.1)189

Frequency-Modulated Light Beam Completes

Feedback Loop for Control System. ..

Stabilized Photoformer Circuit Feeds Func-

tion of Input Voltage to Analog Computer .

POWER SUPPL y CONTROL CIRCUITS .

Overcurrent Protection Circuit for Transistor

PowerSupply. Energy in Received Radio Waves Provides

Operating Power for Transistor Circuits .

Junction Transistor Serves as Ripple Filter

for Low- Voltage Power Supply. Control of Instantaneous Voltage and Current

in Power Transistor Boosts Efficiency. .

Servo Discriminator Feeding Silicon-Diode

Modulator Controls Aircraft Alternator

Frequency' Crystal-Controlled 28- Volt Bistable Voltage-

Doubling Chopper Drives Synchronous

Clock. Photoflash Power Conyerters Use Power

Transistors in Symmetrical Inverter and

Blocking Oscillator Circuits. Zener Diodes and SilIcon Transistor Regu-

late Output of Bridge Rectifier. Controlled-Firing- Time Thyratron Inverter

Eliminates Bulky Saturable Reactors. .

Solid-State Rectifiers and High-Current Reg-

ulator Tubes Eliminate Power Transformer

in Regulated Power Supplies. R-F Power Supply Replaces Vibrator Supply

for Portable Infrared Viewers. Regulated Transistor Power Supply Uses Di-

rect-Coupled Amplifier in Feedback Loop .

Transistorized Power and Bridge Excitation

Supply for Strain-Gage System. ...

High-Voltage Power Supply Uses 12.5-KC

Oscillator and Corona-Tube Regulator. .

Variable-Frequency Power Supply for Servo

Testing Uses Pentode Cathode Followers .

Triode Serves as Grid Leak Resistor in. Regu-

lated Power Supply.

Beat-Frequency Subaudio Oscillator Requires

No Output Amplifier. Electronic Organ Uses Neon Lamps as Tone

Generators and Frequency Dividers. ..

Closed-Loop Regulator Controls High-Power

Induction Heater. Direct-Coupled Multiple-Feedback R-C Os-

cillator Covers 4 CPS to 350 KC. ...

Variable-Frequency Oscillator Controls Fir-

ing Rate of Machine Guns. Double- Triode and Two Diodes Generate

Negative-Going Staircase. Oscillator Provides Beeps Required when Re-

cording Telephone Conversations. ...

Thyratron Delivers Predictable Half-Sine

Pulse When Triggered. Fork-Controlled Generator Provides Seven

Standard Audio Frequencies Simultane-

ously : ...

Oscillator-Sharing Simplifies Circuit of Elec-

tronicOrgan Neon Tubes Back to Back Generate Keep-

Alive Pulses for Recorder. Low-Distortion Audio Oscillator Uses Biased

Diodes to Eliminate Hunting. Transistorized Crystal-Controlled I-MC Os-

cillator Is Highly Stable. Sonar Target Simulator Produces Echo Sig-

nal for Servicing Purposes. Variable-Gain Negative-Feedback Amplifier

Stabilizes Feedback Oscillator. Frequency Meter Quickly Measures Dynamic

Compliance of Phono Cartridge. ...

Frequency Comparator Applies Error Voltage

to Repeller of Klystron Oscillator. ...

216189

216

PHOTOELECTRIC CIRCUITS 191

218

191 219

192 220

222]9~

195 222

195 224

19fi 225

198 226

198 227

Camera Shutter Tester Uses Photodiode to

Feed D-C Amplifier. Multiplier Phototube on Lathe Drives Elec-

tronic Counter That Reads Microinches ..

Photoelectric Function Generator Uses Oscil-

loscope as Light Source. Photoelectric Ill~ination Control Responds

to Bright Sunlight. Vidicon Camera Circuits Detect Changes in

Nearly Identic It Photographs. Banks of MultiplIer Phototubes Give Coor-

dinates of Test Missile. Photocell-Controlled Multivibrator Gener-

ates Tone Frequency Proportional to Light .

Photoelectric Counter Checks Frame Rate of

MovieCamera Three-Phototube Pickup Checks Hue and

Saturation of Color TV Tubes.

PROCESS CONTROL CIRCUITS. ...

Basic Amplifier, Modulator, Demodulator and

Power Supply Circuits for Process Control.

Audio-Level Trigger Circuit Shuts,Off Crys-

tal Lapping Machine. Closed-Loop Controller Provides Rate and

ResetAction Three-Channel Decade Counter Controls

Flow of Liquid Plastics. ~Pressure Transmitter Controls Tuned Oscil-

lator for Set-Point Control. Galvilnometer-Type Controller Feeds F-M

Circuit Giving D-C Output.199 227

x

CONTENTS

Servo-Controlled Pump Maintains Constant

Fluid Volume. 228

REMOTE CONTROL CIRCUITS 230

230

230

232

233264

234

235

236

237

240

Transmitter and Receiver Circuits for Radio-

Controlled Garage-Door Opener. ...

Single-Stage Franklin Superregenerator for

Radio Remote Control. Ultrasonic Gong Controls Four Functions in

TV Set. Carrier-Current.Control Through Power Line

Tunes TV Set. Microwave Link Controls Fog Alarm on un-

attended Island Site. Selective A-F Circuit Fires Squib or Operates

Relay for Missile Control. Ultrasonic Tones Control Tuning Motor in

TV Set. Tone-Actl1ated Programmer Mixes Records

with Taped Announcements. Two-Transistor Superregenerative Remote

Control Receiver. Flashlight Operates Photoelectric Remote

Control for TV Set. 241

SERVOMECHANISM CIRCUITR 242

242

SWITCHING CIRCUITS Simple Electronic Switch Gives Transient-

Free Commutating Zener Diode Controls Triggering Level of

Push-Pull Transistor Relay. Ring-of-Five Neon-Lamp Oscillator Pro-

vides Sequential Switching. Clearing, Resetting and Transfer-Storage

Circuits for Beam-Switching Tubes. ..

D-C Voltage Comparator Actuates High-

Speed Transistorized Electronic Switch. .

Balanced -Input Transistorized Electronic

Relay. Two-Way Sampling Switch Using compen-

sated Comparators Has High Input Impe-

dance. Beam-Switching Tube Switches Low-Level

Capacitive Transducer Signals. Voice-Actuated Switching Circuit Controls

Microwave Party Li~e ' .

Triode Makes Relay Pull-In and Drop-Out

Currents Equal. Multichannel Electronic Switch for Oscillo-

scope Uses Flip-Flops in Ring. Electronic Crowbar Shorts Power Supply of

High-Power Transmitting Tube to Prevent

Flash-Arc Damage. Coincidence Diodes Gate Transistorized Six-

Channel Electronic Switch. Saturated and Nonsaturated TransistOJ; Flip-

Flops Use Single and Double Triggering .

Ultrasonic Switch Controls Diversity Re-

ceivers

274242

27.~243

276244

24.1j 276

246 276

247 27R

248 280

250281

251 283

251 284

252 288

Servo Amplifiers Use Power Transistors to

Drive A-C or D-C Motors. .: ...

Silicon Power Transistors Drive Split Control

Winding or Servo-Motor. Zener Diode in Feedback Loop Provides AGC

forA-CServo Servo Accelerometer Uses R-F Oscillator with

NuIIBalance Servo Positioner for Component Inserter Is

Programmed by Cards or Tape. Self-Setting Servo Gate Rejects Random In-

terference Pulses. Negative Feedback Provides Stability for

Push-Pull Transistor Servo Amplifier. .

Servo System Controlled by Radar I-F Signal

Tunes Magnetron for Search or AFC ...

Phase-Seleciive Gate Ilejects Quadrature Sig-

nals in Servo Loop. Transistorized Relay ~ervo Uses Step-Func-

ti on Potentiometer. Transistorized Servo Amplifier Drives Two-

Speed Motor Directly. Four- Transistor Preamp-lifier Feeds Tran-

sistor-Magnetic Amplifier Servo. ...

Simple Infrared Analyzer Detects Leaks in

Air Chamber. Phase-Stabilized UHF Servo Amplifier Con-

trols Steerable Antenna.

253 289

TELEMETERING CONTROL CIRCUITS ,

Transistorized Micromicroammeter FeedsRadiation Data to Satellite Telemeter. ,

Underwater Telemetering System Uses Four60-KC Ultrasonic Links, , ..., ,

Pulse-Position Telemetry Demodulator Com-pensates for Parameter Variations , .,

Transistorized Telemeter Transmitter forBalloon-Borne Radiation Detection. , .

Transistorized PDM Keyer Improves Air-borne Telemetering System, , , , , .

Telemetering Equipment in Sounding BalloonMonitors Cosmic Radiation. , , , , ,

Encoded Shaft P~ition Data Is Transmittedover Telephone Line, , , , , , " ,

Telemetering Transmitter in Rocket ProducesPWM F-M Signals. .., , ., .,

Eight-Transistor Transmitter TelemetersScalp Voltages. , , ., , , ., ,

Telemetering Demodulator Converts Wide-Band F-M Data to PFM Data .256 289

XI

CONTENTS

292 307

292 307

29~ 307

30829Fi

TEMPERATURE CONTROL CIRCUITS

Proportional Heat Control Maintains Ther-

mal Chamber at Preset Value Thennopile Actuates Current-Adjusting

Temperature Controller. Servo-Balanced Bridge for Compensated

Thermocouple Gives Jet Engine Tempera-

ture Germanium Transistor Serves as Thennostat

for (;old .Tlmct.inn -

309297

310298

31229~

312298

~14299

314~Ol

316

~O2 ~1.7

319~o~

321

304321

304 322

TIMING CIRCUITS. Extending Linearity Range of Thyratron In-

tervalTimer Phantastron Circuit and Miller Integrator

Used in Exposure Timer. Millisecond Timer and Thyratrons Stop Die-

Cutting Press after Cut- Through. ...

Doppler Radar Speed Meter Checks Highway

Traffic. Regenerative Frequency Dividers for I-MC

Crystal Source Provide l-KC Power for

Precision Clock. Four-Thyratron Timer Triggered by Vertical

Drive Pulses Exposes Camera for One TV

Frame. Double- Triggering Improves Stability of

Phantastron Frequency Divider. ...

Current Transformer and Electronic Relay

Turn on Running- Time Meter When Any

Power Tool Is Used. Ticks of Master Clock Synchronize Time

Base of Cathode-Ray Watch Timer. ..

Astable Multivibrator Controls Pentode Gate

for Pulsing Circuit.

305 323

ULTRASONIC CIRCUITS. Doppler-Effect Ultrasonic Burglar and Fire

Alarm Battery-Operated Resonance-Type Ultra-

sonic Thickness Gage. Ultrasonic Vibrator Makes Beer Foam to

DriveOutAir. Adjustable Ultrasonic Paths in Air Simulate

Multipath Communications. Ultrasonic Pulses Detect Flaws in Coating of

Uranium Slug. Two-Transistor Broadband Ultrasonic Pre-

amplifier for Hydrophones. Pulsed Frequency-Modulated System Ana-

lyzes Ultrasonic Signal Returns. ...

Piezoelectric Transducer Drives Tip of Ultra-

sonic Soldering Iron. Ultrasonic Phase Meter Measures Subsurface

Water Velocity. Quartz-in- Water Delay Line Simulates Radar

Moving Targets. Two-Receiver Ultrasonic System Measures

Propagation in Sea Water. Driver for Magnetostriction Transducer of

Ultrasonic Impact Grinder. WELDING CONTROL CIRCUITS. ...

Capacitor-Discharge Spotwelder Control

Handles Metal Foils. Timer Controls Thyratrons in High-Speed

Resistance Welder Five-Function Programming Timer Con-

trols Electrode Welder. Toroid Feeding A-C Electronic Voltmeter

Measures Spot-Welding Current. ...~O6 325

.

."

xii