UBM Tech
UBM Tech

Old electronics books scanned and free online in pdf format

-December 29, 2008

This page has a bunch of electronics books in pdf format that the guy got by cutting up books and scanning them into Acrobat. I like these old textbooks because in the old days the people that wrote books were trying to teach you as opposed to impress you with jargon and math. Thanks to my buddy Steve Williams who found this treasure trove. If anyone needs a great technician, he is looking for work. Lots of audio and tube stuff, but what caught my eye was the “400 Ideas for Design” from Electronic Design magazine in 1964 (20 meg pdf). Go get it before the lawyers take it down. I took the table of contents and OCR’ed it so you can see the content below.


Transistor Improves Common-Mode Rejection in Difference Amplifier            1

Transistor Chain Forms High Voltage Amplifier            1

Common-Emitter Circuit Has Emitter-Follower Characteristics            2

Cascade Amplifier Stage Extends Receiving Tube Use                  3

Complementary Transistors Form Two-Stage, High-Gain Amplifier 3

AF Tuned Amplifier Has Adjustable Bandwidth        4

Grounded-Grid Circuit Simplifies Microphone Input    5

Modified Cathode Follower Dissipates Less Power 5

Balanced Transformer Windings Can Be Single-Ended or Push-Pull       5

VR Tube Replaces Screen Resistor in Push-Pull Output Stage    6

Cathode-Follower Coupling Yields High Gain Bandwidth        6

Bypassed Bias Resistor Increases Emitter-Follower Input Z          7

AC Amplifier Is Wide Band, Less Bulky            7

Ungrounded Shield Reduces Effective Cable Capacitance     8

DC-Servo Amplifier Has Single-Ended Drive    9

Double Coupling Capacitors Avoid Leakage Current 9

Variable-Gain Amplifier Has 40-Db Range   9

Wien-Bridge Amplifier Has Selectivity with Stable Gain       10

Hybrid DC Amplifier Replaces Output Transformer      11

Amplifier Design Provides 20-Megohm Input 11

Short-Cut Connection Simplifies Transformer-Coupled Biasing 12

Low-Level Preamplifier Has High Impedance Input    12

Gain Control Maintains Differential Amp’s DC Balance            13

Variable Resistance FET Gives 75-Db Gain Control     13

Selective AF Amplifier Has Simplified Feedback Circuit 14

Three-Transistor Buffer Offers Lower Offset and Drift           14

Isolation Unit Amplifies DC Currents and Voltages           15

Field Effect Transistor Improves Low Pass Filter Action 15

Selective Amplifier Uses Bridged-T Control 16

Decoupling Capacitor Eliminated By Bifilar Transformer      16

Programmed Video Gain Control Is Linear Over 6-Db Range         17

Neutralization Extends Range of Differential Amplifiers         17

Low-Noise Preamplifier Gives High Input Impedance       18

Diodes Prevent Damage to Transistor Emitter Followers         18

Stable DC Amplifier Makes Good Level Changer 19

Five-Amp DC Current Amplifier Has Low Output Impedance       20

Bridged-T Feedback Yields “Maximally Flat” Response 20

Audio Frequency Amplifier Responds Over 10-Cps Bandwidth        21

Single-Ended Amplifier Can Reject Common-Mode Signals   22

Positive, Negative Feedback Combine to Reduce Noise   22

Linear Modulation of Transistor Power Amplifiers         23

Modified Emitter Follower Has Very Low Output Impedance       24

Desk Calculator Evaluates Standard Polynomial Expression        25

Log-Log Slide-Rule Converts Voltage, Power Ratios Directly to Db   25

Simplified Conversion Eliminates Slide-Rule Step            25

Slide-Rule Converts Angles to Radians Quickly            26

Straight-Line Graph Yields Logs to Base 2 26

Short-Cut Squares Numbers Rapidly on Sight     26

Straight-Line Representations Simplify Data Comparisons    26

Staggered Columns Identify Printed Data Easily       27

Power Gain Plot Can Be Made Directly from Measurements 27

Modified Formula Helps Calculate Q More Accurately        28

Curve Helps Determine Unmatched Transformer Response         28


Eccentric Knob Trimmer Covers 200-Cycle Tuning Range   29

FET Makes High Level Phase-Sensitive Detector           29

Single-Stage AGC Has 40-Db Control Range   30

Transistor Transmitter Has High-Level DSB Modulation       30

Improving Response of Class-A Power Output Stages   31

Double-Balanced Mixer Uses No Transformers    31

Signal-Conditioning Instrumentation Networks         32

Push-Pull Tripler Improves Gain at VHF 32

Simple VLF Receiver Uses Single Tuned Stage    33

Double Conversion Improves Transistorized FM Receivers   33

Extending the Range of Pi Network Tank Circuits 34

Band Switcher Uses Light-Sensitive Resistors          35

Unpolarized Clipper Makes AFC’Let Go’ of Strong Signal Channels          35

Transistor Squelch Circuit Uses Minimum of Components 36

Photoconductor Commutator Has Simplicity and Isolation     37

Reducing Power Dissipation in Emitter-Follower Circuits 37

Computer Circuit Provides Simple Transistor Squelch            38

Neon Tube Serves As Tuning Indicator for FM Receiver    38

AND/OR Gate Multiplexer Uses Voltage-Amplitude Coding 39

Bootstrap Circuit Uses Grid Bias to Obtain Linear Charging           39

SCR Pulse Stretcher Resets After Pulse Train       40

FM Stereo Indicator Uses Minimum of Components     40


Neon Lamp Matrix Stores Information Visually            41

Low Impedance Transistor Circuit Drives Coaxial Line     41

Low-Level Signal Gate Circuit Relies on Diode Conduction Potential           42

Transistorized Neon Drivers Eliminate Reverse Leakage Glow 42

Summing Network Varies AC-DC Components of Input Saw Tooth   43

Pulse Transformer Helps Provide Two-Input, Exclusive-Or Logic    44

Camera Lens and Solar Cell Make Pulse Generator         44

Reduce Delay Time in Binary Counters          45

Thyratron Delays Digital Clock Pulse      45

Biased Emitter Follower Limits Pulse Amplitude         45

High-Speed Pulse-Stretcher Depends Upon Delay Line Time     46

Modified One-Shot Multivibrator Acts As Pulse Decoder           46

Logic Signal Intensifies Scope Display 47

Delay Line Added for Constant-Width Pulse      48

Simplified Squelch Circuit Uses Back Biased Diode    48

Pushbutton-Actuated Circuit Gates Single Synchronous Pulse    49

Variable Capacitor Adjusts Chopping Rate 50

Neon Tube R-C Oscillator Makes Low Repetition Rate Timer   50

Capacitors Halve Reverse-Voltage in Flux-Switching Circuit 50

Digital FM Technique Used to Delay Analog Signal   51

Holding Capacitor Fires Neon on Short Pulses   52

Blocking Diodes Stabilize Multivibrator Frequency        52

Modified Circuit Limits Pulse Amplitude More Effectively         52

Pulse Inverter for Positive and Negative Pulses            53

Zener Diode Circuit Shifts Level of Uniform Amplitude Pulses   53

Suppressor Grid Voltage Varied for Constant Amplitude Pulses   54

LF Multivibrator Uses Unijunction Transistors        54

Tunnel Diode Acts As Sensitive Voltage Level Detector           54

Feedback Amplifier Generates Narrow Pulses 55

Cut-Off Diode Triggers Fast Output Pulses   56

Varying Multivibrator Bias Changes Output Frequency        56

Zener Diodes Trigger Time-Sequenced Pulses   57

Solid State Relay Varies Operational Amplifier Gain 58

Novel Multivibrator Circuit Uses Gated Beam Tube    58

Two Relay Contacts Clear Integrator for Rapid Operation         59

Holding Resistor Allows Narrow Pulse Triggering of SCR Circuit      60

Trigger Pulse Generates Two Separate Outputs            61

Pulse Circuit Provides Sharp, Variable Pulse Delays     61

Scope Measures Propagation Delay in Asynchronous Logic    62

“See-Saw” Multivibrator Uses a Single Capacitor         63

Starter Circuit Prevents Stall of Free-Running Multi   63

Bistable Switch Gates Clock Pulses to Counting Circuitry           63

One-Shot Pulse Output Has Greater Than 100% Duty Cycle   64

Fast Pulse Train Synched to Slow Input Trigger 64

Steering Diodes Prevent Spurious Multi Triggering         65

Constant Output Signal Maintained by Continuous Pulse Train       65

Pentode “Multi” Standardizes Long Period Square Waves 66

Emitter-Coupled Limiter Produces HF Square Waves 66

Modified Multi Generates Output Gate with Each Trigger 67

High-Gain Pulse Amplifier Uses Complementary Transistors        67

Circuit Transmits Two Pulse-Trains Over Single Channel            68

Pulse-Selection System Uses Analog Techniques       68

Extra Transistor Reduces Turn-Off Times in One-Shot Multi            69

High-Power AND Gate Uses Discharging Capacitor         69

Simplified Gate Driver Reduces Delay Between Outputs            70

RC-”Blocking Oscillator” Produces Complementary Pulses   70

Long Period Multivibrator Reduces Timing Capacitor Size 70

Gated Square Waves Vary Pulse Width of Output Train     71

Complementary-Pair Multi Has Long Pulses, Small Capacitor         72

Square Wave Generator Has 3.3-10 Mc Range   72

Clock Pulses Generated By Magnetic Core Timer   73

Sequential Counter Stepper Uses Error-Correcting Code    73

Hybrid Three-Level Logic Requires Fewer Components     74

RC Pair Safely Sets Initial State of Relay Driver   74

Delayed-Pulse Generator Uses Fewer Components     75

SCR Drives Cold Cathode Counter Tube               75

Simple Gates Provide Binary Scale-of-Ten Counter            76

Mercury Relay Makes Fast-Rise Pulse Generator         76

Blocking Oscillator-And Gate Produces Standard Output Pulse     77

Transistorized Voltage-Frequency Converter Operates Linearly            77

Delay-Line Discriminator Detects Sequences of Pulse    78

FM Preserves Pulse Polarity in Ultrasonic Delay Lines      78

Indicating Shift Register Uses Silicon-Controlled Rectifiers          78

Tunnel Diode Triggers Avalanche Pulse Generator         79

Fixed Interval Timer Gates Random Pulse Stream 79

Transistor Stage Yields Polarity-Controlled Output 80

SCR Charge-Discharge Circuit Samples Slow Rep-Rate Pulses   80

Variable-Width Pulse Generator Provides Fast Rise/Fall Times 81

Root Taker Using Biased Diode Networks                     81

Gate Circuit Inhibits Pulses on Command                82

Two-Transistors, Feedback Produce Free-Running Pulser 82

Inverted Exclusive-OR Circuit Compares Binary Bits        83

Zener, Diode Bridge Forms Double-Ended Clipper 83

Circuit Squares DC Input Voltage                        83

Cascode Circuit Compensates for Heater-Voltage Sensitivity         84

Simple Transistor Circuits Generate Phantastron Sweeps            84

Biased-On AC Amplifier Boosts Low-Level Pulses     85

TD, Current-Mode Switch Deliver Fast 1-w Pulse            85

Photoelectric Elements Help Analog Circuits Divide, Multiply            86

Extra Triode Unloads Analog Computer Signal Source   87

Exclusive OR Circuit Uses Three Transistors        87

Differential ‘Exclusive OR’ Reduces Logic Modules           88

Majority-Logic Adder Cuts Component Needs 88

Diode Sets Flip-Flops for Initial State at Turn-On           89

Direct-Coupled Transistors Provide Simple Parity Check    90

Exclusive-OR Needs No Complement                 90

Mousetrap Generator Builds a Better Pulse                91

Magnetic Tape Detects Sections of Rotating Wheel 91

Neon Driver Circuit Uses Low Voltage Transistor         92

Zener Diode Reduces Schmitt Trigger Hysteresis         93

Short-Duration Pulses Drive Visual Indicators         93

Starter Circuit Guides Counter-Tube Beam               94

Simplified Pulse Circuit Has Low Output Impedance       94

Temperature Sensitive Resistors Are Low Cost Function Inverters           95

Modified NOR Circuit Automatically Presets Flip-Flop     95

Fast Squaring Circuit Preserves Phase Information       96


Quotient Circuit Substitutes for Difference Variable           97

Transistor Improves Response and Speed Regulation of DC Motor        97

Bridge Circuit Temperature Stabilizes Relay Operation         98

Filament Voltage Controls Thyratron Cut-Off       98

Diodes Allow Two-Wire Control of Limit-Switched Motor 99

Silicon-Controlled Rectifiers Vary Servo Motor Speed, Reduce Input Power 99

Inexpensive Time-Delay Drop-Out Uses a Thermal Relay    99

Driver Closes Relays Rapidly with Almost Bounceless Contacts           100

Amplified Capacitor Suppresses Are More Completely       100

Miller Effect Extends Relay Close Time                   101

Triggering of Controlled Rectifier Fires Its Series Mate 101

Resistor Eliminates VR Tube Oscillations                   102

Neon Bulb Detects Phase Failure             102

Tiny Thermistor Protects Gear Train from Transient Damage            102

Neon Tube Limits Signals, Indicates Limiting Operation         103

A Cadmium Sulfide Photocell Indicator                       103

Choke-Zener Diode Combination Reduces Regulator Ripple 103

Square-Loop Core Transformer Protects Regulating Transistor         104

Oscillator Coil Doubles As Step-Up Transformer      104

Predetermined Input Level Cuts Off Transistor, Sets Output 105

Biased Transistor Pair Monitors Within Set Limits   105

Transistorized Output Switch Limits Short-Circuit Current 105

Feedback Helps Flip Output of Zero-Crossing Detector           106

Separate Lamps Controlled Over Single Line                  106

Photoelectric Circuit Operates with High Light Resolution        107

Signal Light Indicates Out-of-Bounds Ripple             107

Temperature Monitor Uses Silicon Transistor Sensor 108

Schmitt Circuit Monitor Triggers on Overloads        108

Current Overload Protectors Use Simplified Designs            109

SCR Relay Flips, Flops on Consecutive Commands       110

Compensating Voltage Reduces Zener Diode Variations         110

Automatic Gain Control Circuit Uses Unijunction Transistor         111

Short Trigger Pulse Turns on SCR, Fires Flash Bulb        111

Unijunction Transistor Attenuates AC with DC           112

Shorting Transistor Reduces SCR Turn-Off Time 113

Versatile Transistorized Alarm Detects Pulse Dropouts 113


Terminal Plate Serves As Common Connecting Point    115

Metal Sponge Provides Contact Between Two Metal Plates     116

Rubber-Core Terminals Hold Wires Securely 116

Mounting Stud Cast from Encapsulating Material            116

Masonite Sheets + Phono Jacks + Holes=Patch Board   117

Effect of Feedback on Gain Shown in Design Chart    117

Component Tolerance Calculator Can Be Built Into Your Slide Rule            118

Amplitude Control in DC-Coupled Circuit Holds DC Level Constant 118

Experimental Circuits Provide Negative Resistance        119

Jury-Rig Coil Winder Employs Pencil Sharpeners        120

Wirewrap Pattern Charge Simplifies Circuit Alterations        120

Heat-Conducting Wafers Dissipate Heat in Micromodules 121

Small DC Capacitors, Diodes Form Equivalent AC Unit      121

Tweeze Your Way to Ring-Free Circuital                122

Metal Foil Sticks to Tube, Conducts Heat             122

Grind Your Own “Precision” Capacitor                     122

Salvaged Tank Coil Yields Precision Potentiometer   123

Printed Wire “Plug-In” Cards Reduce Number of Card Types      123

Memorized Data Generate Complete Wire Tables 124

Wire Table Gives Quick IR Drop Data                    124

Chart Simplifies Transformer Design             125


Filter Designs Combine Bias and Frequency Components     126

Narrow-Band Filter Relies on Demodulating Circuit 127

Forward Biased Diode Gives Protection for Crystal Filters   128

Low-Pass Filter Converts Square Waves to Sine 128

Novel Notch Filter Is Easy to Time for Null    129


Differential Monitor Detects Error Voltage            130

Detected AM Chopped for Per-Cent Modulation Measurement    131

Visual Display Helps Determine Tuning Fork Q 132

Sensitive Pulsing Circuit Measures 10-” Amp     133

Inexpensive Megohmmeter Measures 50 to 50,000 Megohms         134

Primary Screen Grid Emission Measuring Technique         134

Switch Cover Protects Transistors from Transient Peaks   135

Polarized Relay Circuit Measures Duty Cycle Electrically        135

Four-Resistor Decade Was Improved Upon    136

Four-Resistor Decade Uses Standard Rotary Switch   136

Plexiglass Reticle Helps Measure Dynamic Impedance       136

Biased Base Clipper Isolates WWV “Tick” Tone    137

Search Coil Locates Noise-Sensitive Circuit Trouble-Spots 137

Oscilloscope Mask Permits Rapid Digital Readout           138

Transistorized Pot Allows Fine DC Voltage Adjustments     138

Q-Meter Measures IF Chassis’ Resistivity         139

Selecting Proper Resistance Simplifies VTVM Range Divider 139

Diode Calibrates RMS Meter for Noise Voltage Readings          139

Universal Ratio Set Is Suitable for Voltage Comparisons    140

Voltmeter-Variable Resistor Measures Zener Current   140

Diodes Checked Out on Single 60-Cycle Tester     141

Z-Axis Blanking Helps Determine Lag or Lead            141

Current Amplifier Increases Null Meter Range    141

Two-Transistor Circuit Increases Null-Detector Sensitivity         142

Small Test Probe Uses Hybrid Isolation Amplifier          142

Balanced Magnetic Fields Determine Pulse Amplitudes       143

Low-Cost Scope Attachment Traces Transistor Characteristic Curves 144

Circuit Calibrates Meter for Sine Waves and Noise   145

Ordinary Diode Protects VTVM from Overload          145

Transistor, Relay Switch Safeguard Sensitive Galvanometer   145

Modified Detector Adds Markers for Frequency Response Tests            146

Visual Readout for Tester Uses Silicon-Controlled Switch 146

Modified Chopper Drives Zero-Center Meter    147

Simple Null Circuit Has Many Applications     148

Testing Field-Effect Devices on Transistor Curve Tracers 148

Determining Voltage Gain of Field-Effect Transistors        149

Simple Meter Circuit Indicates Transistor Beta 149

Amplifier Test Method Uses No External Source 150

Sensitive Current Detector Indicates Direction of Flow    150

Malfunction Indicator Employs Filament Transformer      151

Microvoltmeter Converts for Differential Measurements 151

Oscilloscope Output Checks Zener Voltage            151

Low-Loss Diodes Reverse Meter Polarity            152

Discontinuity Tester Is Insensitive to Noise   152

Transistorized Voltmeter Has 1000 Megohm Impedance       153

Simple Series Regulator Gives Binary-Analog Conversion       154

Testing Unijunction Units on Transistor Curve Tracers 154

Square-Wave Doubler Uses Four-Layer Diode   155

DC Presence Indicator Checks Three Voltages           155

Simple Voltage Calibrator Has Stable 10-Kc Output 156

Resonant Reed Relays Make Simple Scope Marker 156

Technique for Simulating Strain-Gage-Transducer Signal   157

Voltage Band Comparator Uses Tube-Transistor Circuit 157

Test Set Displays Zener Diode Characteristics 158

Automatic Continuity Detector Performs Double Test Function           158

Biased Diode Reduces Non-Linearity of AC Meters 159

Burned Out Transistors Save Time and Money in Heat Tests    160

Low-Current Threshold Detector Uses Backward Diode   160

Comparator Circuit Simplifies Integrator Time-Constant Check 161

Reducing Effect of Intermittent Instrumentation Loads   161

Double-Exposure Reveals Zener’s Zero-Temp Coefficient        162

Temperature-Stabilizing Emitter Followers            162

Voltage Comparator Uses Tunnel Diode Flip-Flops    163


Microwave Mixer Diode Makes Sensitive, Broadband Video Detector            164

Fabrication from Plastic Clay Speeds Microwave Matching          166

Klystron Is Switched Off, But Remains On to Avoid Cooling            166

Meter Relays Protect Travelling Wave Tubes     167

Woods Metal Good for Plugging Plumbing            167

Antenna-Matching Transformer Keeps VSWR Low Over Wide Band       168


LC Ringing Circuit Sharpens Oscillator Trigger Points   170

Tunnel Diode Doubles Doubled Frequency        170

Simple Transistor Oscillator for 5 to 50 me. Frequency Range   171

RC Pairs Provide VFO with Quadrature Outputs            172

Crystal Oscillator Provides Good Load Isolation 173

Dual Frequency Oscillator Built with 6EZ8 Tube    173

Simple Circuit Halves 20-Mc Supply Frequency        174

A Two-Transistor Amplitude-Modulated Oscillator          174

Tank Circuit Helps Stabilize Quick-Starting Gated Oscillator          175

Tuning Fork Oscillator Produces Square Waves Directly            175

Single Potentiometer Adjusts Range of Simple VFO 176

Unijunction Oscillator Has Frequency Trim Control 177

Gated Tunnel-Diode Oscillator                      177

Sweep-Frequency Oscillator Operates on Collector Capacity           178

Clamp Circuit Improves Blocking Oscillator Duty Cycle   178

Bilateral Crystal Oscillator Has Two-Frequency Output 179

Diode-Resistor Pair Improves One-Shot Multi Fall Time          179

Zener-Biased BO Has High Repetition Rate 180

Regenerative Stage Enhances Flip-Flop Power Output   180

Obtaining Zero Reference for Flip-Flop Square-Wave Output 181

Zener Diode Helps Set Blocking Oscillator Synch   181

Ring Multi Generates Fast, Variable Output Pulses   182

Voltage Control Starts Free-Running Multivibrator     183

Current-Mode Flip-Flop Has Dual Voltage Outputs            183

Shockley Diode Modernizes Neon-Tube Oscillator          183

Tunable Multivibrator Starts Reliably 184

Voltage-Controlled Oscillator Exceeds 2-to-1 Frequency Range   184

Extending Operating Range of Unijunction Timing Circuits 185

Unijunction Oscillator Has Negative Pulse Output 185

Monostable Multivibrator Has High Run/Recovery Ratio    186

Circuit Modification Speeds Square-Wave Rise Time         186

One-Shot Generator Gives Variable Pulse Width      187

One-Shot Multivibrator Allows Voltage Controlled Pulse Width      188

Field-Effect Transistors Give Ultra-Linear LF Sawtooth          188

Unijunction Oscillator Gives 30-Sec Sweep 188

Series Oscillators Produce Modulated Output 189

Input Pulse Width Controls Simple Ramp Generator         189

Four-Layer Diode Makes Simple Astable Multivibrator     190

Blocking Oscillator Operates Without Transformer      190

Unijunction Generator Has Variable Square-Wave Output 191

Varistor Stabilizes Phase-Shift Oscillator          191

Three-Mode Multivibrator Uses Single Control Wire    192

Multivibrator Generator Gives One Pulse Per Hour Output 192

Voltage Changes Transmitted As Shifts in Frequency        193

Modified Modulator Yields Wide-Band FM Transmitter       193

Sine-Wave Modulator Uses Complementary Transistor Pair 194

Regenerative Switch Demodulates Sinusoid           195

Dual-Polarity Signal Drive Uses Cascode Emitter Follower           196

Low Impedance Line Driver Uses Standard Coils    196

Transistor Trigger Pulses Fire Tube & Blocking Oscillator          197


Dynamotor Power Source Supplies Low Voltage, High Current 198

Four Extra Diodes Insure Load Sharing in High Voltage Bridge 199

Simple CRT High Voltage Supply Regulator          199

Relay-Zener Circuit Protects Nickel-Cad Batteries           200

Emitter-Follower Stabilizes Two-Transistor Regulator          200

Junk-Box Converter Supplies High DC Voltage      201

PNP Circuit Supplies Constant-Current Into Load    201

Variable DC Output Obtained from SCR Circuit      201

Added Stage Protects Regulator from High Voltage    202

Corrector and Zener Diode Reduce Ripple in Power Supply 203

Light Bulb Improves Zener-Regulated Supply 203

Regulated Power Supply Uses Low-Cost Diodes     204

Modified Regulator Is Made More Sensitive to Output Changes           204

Solid-State Oscillator Supplies Three-Phase Power    205

“Junk-Box” Current Limiter Protects Breadboard Equipment        206

Pentode Replaces Triode for Current-Limiting in Tube Supply 206

Standby Batteries Protect Supply Against AC Power Loss      207

Transient Clipper for DC Converters                   208

Voltage, Current Limiter Protects Circuitry from Shorts and Overs   208

Battery Boost Circuit Uses Autotransformer Action            209

Battery Charger Protects Small Nickel-Cadmium Cells 210

Dual-Voltage Power Supply Uses Dual-Purpose Transistors        210

Overload Protector Dissipates Little Power 211

Universal Regulator Adapts to Power-Supply Needs 212

Tapped-Primary Transformer Doubles As Autotransformer           213

Current Limiter Protects Magnetic Amplifier Supply 213

Series-Shunt Regulated Supply Improves Transient Regulation        214

Low-Cost SCR Multivibrator Yields 20 Kv from 20-V Input    214

Simple Overload Circuit Protects DC Power Supplies           215

Dual Transformers Extend Voltage Control Range 215

Voltage Sensor Monitors Multiple Power Supply Outputs 216

Counter Drive Circuit Monitors AC-Line Frequency 216

Motor Control System Isolates AC Lines from DC Circuits      217

Inexpensive DC-to-DC Converter Operates Without Rectifier Diodes 218

Simple Current-Limited Voltage Source 218

Lighted Photocell Replaces Mercury Bias Battery 218

VR Tube, Removed from Load, Is Freed By Source        219

Regulator-Doubler Eliminates Need for Second Power Supply 219

SCR Circuit Breaker Has Fast Operation 220


Flip-Flop Relay Driver Eliminates Emitter Follower           221

Multi-Buffered Switch Eliminates Contact Bounce 221

Relay Bridging Avoided Through Isolation Scheme            222

Stepping Switch Provides Fool-Proof Synchronization            222

`Constant-Current’ Supply Interlocks Relay Network 223

Transistor-Relay Combination Forms Low-Cost Switching Circuit 224

Voltage-Controlled Relay Selector System 224

Low Current Steps High Current Stepping Switch 225

Lamp Heating Time Speeds Relay Operation         226

Relay Sequencing Circuit Requires Minimum of Components     227

Tuned Relay Coil Switches at Low Current            227

Unijunction Oscillator Insures That Power Converter Will Start     228

DC Relay Draws Extremely Low Current 228

Biased Reed Relays Recognize Polarity 229

Full-Wave SCR Relay Gives Undistorted Output 230

Constant Percentage Gate Operates Over Wide Range   230

Delayed SCR Turn-on Eliminates Contact Bounce 231

Transistor Ignition System Improves Engine Performance     232

Flip-Flop Switch Eliminates Contact Bounce 232

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