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Success in

ELECTRONICS

Tom DuncanSuccess in

ELECTRONICS

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Success in

ELECTRONICS

Tom Duncan, B. Sc.

JOHN MURRAY

© Tom Duncan 1983

Fisrt published 1983

Reprinted 1984 and 1986 (twice) with revisions; 1987, 1989

All rights reserved. No part of this publication may be

reproduced, copied or transmitted save with the written

permission of John Murray (publisher) Ltd, 50 Albemarle

Street, London WIX 4BD, or in accordance with the

provisions of the Copyright Act 1956 (as amended), or

under the terms of any licence permitting limited copying

issued by The Copyright Licesing Agency, 33 – 34 Alferd

Place, London WCIE 7DP.

Any person who does any anauthorised act in relation to

this publication may be liable to criminal prosecution

and civil claims for damages.

Typesed in Great Britain by

J. W. Arrowsmith Ltd, Bristol BS3 2NT

Made and Printed in Great Britain by

Richard Clay Ltd, Bungay, Suffolk

British Library Cataloguing in Publication Data

Duncan, Tom

Succes in Electronics, - (Success Study books)

1. Electronics 1. Title

537,5 TK7815

ISBN 0 – 7195 – 4015 – 1

Foreword

Success in electronics is intended for anyone who wishes

to gain an understanding of the basic principle of

electronics as they are applied in communication, control

and computer system. Very little previous knowledge of

electricity is assumed, and mathematical requirements are

kept to a minimum. The treatment is practically

orientated and actual devices with their uses are

considered in the hope that the reader may be encouraged

to ‘do’ some electronics. For this reason books on

project work are listed in the Further Reading section at

the end of Part Five of this volume.

While not following any practicular examination

syllabus, the book is appropriate for students taking

GCSE. BTEC (Electronics NII and NIII), City & Guilds and

A-level courses.

Part One deals with Basic Electricity, *Part Two

with Components, Part Three and Four with Linier and

Digital Circuits respectively ( in both discrete

component and integrated circuit form) and in Part Five

an outline is given of some Electronics System. If

desired, Part Four may be taken before Part Three. At the

end of most Units, as an aid to checking progress, there

are Revision Questions and Prblems (mostly numerical).

Answers are given, where appropriate, at the end of the

book.

T. D.

Acknowledgement

For permission to use copyright photograph thanks are dueto: Austin Rover Group Ltd. (Fig. 1.1(a)); Avo Ltd.(2.10); British Telecom (1.1(b), (f)); Computer GamesLtd. (1.1 (e)); Department of Industry (13.5(b));Ferranti Electronics Ltd. (13.1); Maplin Electronics Ltd.

(5.7(a), (b), 6.15(d), 9.9(a), 9.10(a)); Mullard Ltd.(13.3, 13.5(a), 19.10); National Coal Board (1.1(d));National Physical Laboratory (Crown Copyright) (1.1(c));Scopex Instrument Ltd. (20.18); STC PLC (18.30(b));Thandar Electronics Ltd. (20.16).

I should like to thank Edward Mallory, LeslieBasford and Jim Hutton who read and critized the bookduring its preparation. I am also much indebted to Dr.Helen Wright for editing the text so meticulously, toIrene Slade, Anne Webster and Helen Syme of John Murray,to my wife who typed the manuscript and to my daughter,Dr. heather Kennett, for help in various ways.

T. D.

Contens

Part One Basic Electricity

Unit 1 Introduction

1.1 Electronics Today 31.2 Electronics System 31.3 Linier and Digital Circuits 61.4 Electronics Diagrams

71.5 Questions 8

Unit 2 Direct Current

2.1 Electric Current9

2.2 Electromotive Force10

2.3 Circuits and Diagrams10

2.4 Potential Difference11

2.5 Resistance 122.6 Worked Examples 132.7 Ammeters, Voltmeters and Multimeters

142.8 Ohm’s Law 152.9 Electric Charge

162.10 Electrical Energy

172.11 Power 182.12 Internal Reistance

192.13 Revision Question

20

2.14 Problems 20

Unit 3 Alternating Current

3.1 Direct and Alternating Currens23

3.2 Frequency 243.3 Waveforms 243.4 Root Mean Square Values

263.5 Meters for Alternating Current

273.6 Revision Question

273.7 Problems 28

Part Two Components

Units 4 Resistors

4.1 About Resistors31

4.2 Fixed Resistors31

4.3 Resistors Markings32

4.4 Resistors in Series34

4.5 Resistors in Parallel 354.6 Variable Resistors

36

4.7 Potential Dividers37

4.8 Worked Examples 394.9 Revision Questions

414.10 Problems 42

Unit 5 Capacitors

5.1 Electronics Today 445.2 Fixed Capacitors 455.3 Variable Capacitors

465.4 Charging a Capacitor

475.5 Capacitor Networks

485.6 Time Constant

505.7 Capacitive Reactance 525.8 CR Coupled Circuits 545.9 Testing Capacitors 555.10 Worked Examples 565.11 Revision Questions 585.12 Problems 60

Unit 6 Inductors

6.1 About Inductors 616.2 Electricity and Magnetism

626.3 How Inductors Work

646.4 Types of Inductor

656.5 Inductive Reactance

66

6.6 Alternating Current Series Circuit67

6.7 About Transformers69

6.8 Types of Transformer71

6.9 Revision Question71

6.10 Problems 72

Unit 7 Semiconductor Diodes

7.1 About Diodes 737.2 Intrinsic Semiconductors

737.3 Extrinsic Semiconductors

757.4 The p-n Junction 777.5 Junction Diode

787.6 Point- contact Diode

807.7 Zener Diode 807.8 Other Dioders

827.9 Revision Questions

827.10 Problems 83

Unit 8 Transistor

8.1 About Transistors 858.2 Junction Transistors

858.3 Junction Transistor – Current Amplifier

87

8.4 Junction Transistor – Characteristics89

8.5 Junction Transistors – Data91

8.6 Junction Transistors – Testing92

8.7 Field Effect Transistor – JUGFET94

8.8 Field Effect Transistor – MOSFET95

8.9 Comparison of Transistors97

8.10 Revision Questions97

8.11 Problems 98

Unit 9 Transducers and Switches

9.1 About Transducers 1009.2 Microphones 1009.3 Loudspeakers, Headphones and Earpieces 1029.4 Photocells 1059.5 Photodiode and Phototransistor 1069.6 Light Emiting Diode (LED) 1079.7 Liquid Crystal and Others Displays* 1109.8 Chatode Ray Tube (CRT) 1119.9 Thermistors 1139.10 Pick – Ups 1149.11 Relays and Reed Switches 1149.12 Mechanical Switches 1169.13 Revision Questions 1189.14 Problems 119

Part Three Linier Circuits

Unit 10 Basic Audio Frequency Amplifiers

10.1 Introduction 12310.2 Voltage Amplifier using a Junction Transistor 12310.3 Worked Example 12510.4 Load Lines, Operating Point and Voltage Gain 12610.5 Stability and Bias 12810.6 Simple Two-stage Voltage Amplifier 12910.7 Voltage Amplifier using an FET 13110.8 Revision Questions 13210.9 Problems 133

Unit 11 More Audio Frequency Amplifier

11.1 Fully – stabilized Voltage Amplifier 13611.2 Worked Example 13711.3 Feedback Equation 13811.4 Negative Feedback 13911.5 Input and Output Impedances 14111.6 Impedance Matching Circuits 14211.7 Power Amplifiers – Single – ended 14411.8 Powers Amlifier – push – pull 14611.9 Decible Scale 14811.10 Noise 15011.11 Revision Questions 15111.12 Problems 152

Unit 12 Radio Frequency Amplifier and Oscillators

12.1 Introduction 15412.2 Oscillatory Circuit 15412.3 Tuned Circuit 15612.4 Radio Frequency Voltage Amplifier 15712.5 High Frequency Amplifiers 15912.6 Radio Frequency Oscillators 16112.7 Audio Frequency Osccillators 16412.8 Relaxation Oscillators 16512.9 Revision Questions 166

12.10 Problems 167

Unit 13 Operational Amplifiers and Linier Intregated Circuits

13.1 About Integrated Circuits (ICs) 16813.2 Operational Amplifier – introduction 17113.3 Operational Amplifier – practical Points 17313.4 Op Amp as an Inverting Amplifier 17513.5 Op Amp as a Summing Amplifier 17713.6 Op Amp as a Non-inverting Amplifier 17813.7 Op Amp with Single Power Supply 18013.8 Op Amp as a Voltage Comparator 18113.9 Other Linier Integrated Circuits 18113.10 How Linier Integrated Circuits Work 18413.11 Revision Questions 18613.12 Problems 187

Part Four Digital Circuits

Unit 14 Basic Switching Circuits

14.1 Introduction 19114.2 Transistor as a Switch 19114.3 Alarm Circuits 19414.4 Logic Gates – Types 19514.5 Logic Gates – Further Points 19814.6 Multivibrators 19914.7 Bisable of Flip – flop 20014.8 Astable

20114.9 Monostable 20314.10 Triggered Flip – flop 20414.11 Schmitt Trigger 20514.12 Revision Questions 207

14.13 Problems209

Unit 15 Decision – making Circuits

15.1 Introduction 21115.2 About Digital Integrated Circuits 21115.3 Digital Integrated Circuits – Practical Points

21215.4 Logic Gates 21315.5 Codes 21515.6 Encoders

21715.7 Decoders 21815.8 Adders 22015.9 Magnitude Comparators 22315.10 Multiplexer 22515.11 Arithmetic Logic Unit 22715.12 Revision Questions and Problems 229

Unit 16 Memory – type Circuits

16.1 Introduction 23116.2 SR Flip – flop 23216.3 T – type Flip – flop 23416.4 D – type Flip-flop 23516.5 JK Flip-flop 23716.6 Shift Registers 23916.7 Counters

24116.8 Memories 24416.9 Memory Circuits 24616.10 Revision Questions and Problems 248

Unit 17 More Digital Ciruits

17.1 Timers 250

17.2 Digital to – analogue Converter 253

17.3 Analogue – to- digital Converter 25517.4 Op Amp as a Multivibrator 25617.5 Waveform Generators 25917.6 Schmitt Trigger 26017.7 Noise Immunity and Interfacing 26117.8 TTL Circuitry 26317.9 CMOS Circuitry 26517.10 Revision Question and Problem 266

Part Five Electronic Systems

Unit 18 Radio, Television and Audio Systems

18.1 Radio Waves 27118.2 Aerials

27218.3 Amplitude Modulated (AM) Radio 27518.4 Frequency Modulated (FM) Radio 27818.5 Black-and-white Television 28018.6 Colour Television 28418.7 Sound Recording 28618.8 Video Recording 28818.9 Digital Electronics in Communications 29018.10 Optical Fibre System 29218.11 Optical Fibres 29318.12 Optical Transmitters 29618.13 Optical Receivers 29618.14 Revision Questions and Problems 296

Unit 19 Digital System and Computers

19.1 Designing Digital Systems 29919.2 Microelectronic Options 30219.3 Digital Watch 30419.4 Electronic Calculator 30419.5 Digital Computer 30619.6 Microprocessor 31119.7 Analogue Computer 312

19.8 Revision Questions and Problems 316

Unit 20 Power Supplies and Test Instruments

20.1 Introduction 31720.2 Rectifier Circuits 31720.3 Smooting Circuits 31920.4 Stabilizing Circuits 32120.5 Power Control 32320.6 Batteries

32420.7 Multimeters 32620.8 Oscilloscopes 32720.9 Signal Generators 32920.10 Revision Question and Problems 331

Appendix 333

Further Reading 335

Answer to Revision Question and Problems 336

Index 346

Part One

Basic Electricity

Unit One

Introduction

1.1 Electronics Today

Advances in electronics have given us pocket calculators,digital watches, heart pacemarkers, computer forindustry, commerce and scientific research, automaticallycontrolled production processes, instant viewing on ourtelevision screens of events on the other side of theworld and host of other applications.

These have become possible largerly because we haveearned how to build compiete circuits, containingthousands of electronic parts, on a tiny wafer of siliconno more than 5 mm square and 0.5 mm thick.Microelectronic is concerned with these ‘denselypopulated’, miniaturized integrated circuits (ICs), or‘chips’ as they are called, which are changing the way welive and work and challenging us to see that the changesare for the better.

Chips are also used to control robots in factories,electric cookers, washing machines and traffic lights,they are the ‘brains’ behind tv games and microcomputer,they form the hearts of maachiner for teaching spellingand arithmetic and can even be used to mix cocktail andrecognize signatures!

Today, electronics is being used to an ever-increasing extend in communication, control and computersystem as well as in domestic products and for medicalcare. Some pf these uses are shown in Fig. 1.1. In thefirst industrial revolution, machines replaced muscles.In the second, now upon us, and brought about bymicroelectronics, brain power is being replaced. Fewareas of human activity are likely to escape.

1.2 Electronic System

After changing inside a electronics system such as radioor television set or a computer, it would not surprisingif you felt slightly discouraged from studyingelectronics. Fortunately things are really less dauntingthan they seem, for which there are two reasons.

First, while an electronics system may have a largenumber of components (parts), there are only a few typesof these. The main ones are resistors, capacitors,inductors, diodes, transistor, switches and transducters.Those used in integrated circuits (transistors, diodes,resistors and capacitors) have the same action as theirdiscrete (separate) counterparts, they difference ismainly one of size.

Second, different electronics system are made upfrom a fairly small number of basic circuits or buildingblocks. Each basic circuits consist of components

(a)

(b) (c)

Fig. 1.1 (a) arc welding computer- controlled robots inoperation on a car production line; (b) earth stationdish aerials like this one use microwaves to beamtelephone calls, television pictures and computer data to‘stationary’ satellites 36000 km in space wich amplifyand reroute the signals to particular earth stations oreven to other satellites; (c)signature recognizingprototype equipment;

(d)

(e)

(f)

(d) MINOS (Mine Operating System) is a computer used incoalfields for the remote of underground plantm such aspumps and samplers of mine air, that is analysedautomatically. It also monitors the volume of coal inunderground bunkers and the movement of coal from thecoal face; (e) an electronic chess set with a sensorysurface which can challenge a player or itself; (f)British Telecom’s Network Switcing Centre in the LondonTelecom Tower is the hearth of the microwave and cablenet work which intercoonects the studios and transmitterof the major sound and TV broadcasting companes.

Fig. 1.2

components

circuits system

Connected in a certain way so that is does particular jobsuch as amplifiying or counting (fig. 1.2).

Before the days of microelectronics, component weremade separately and then wired together to give therequired circuit. Today they are also produced integratedcircuit form, completed with interconnections, more orles all at the same time. The extend of the integrationis now so great that the distinction between a circuitand system in often less clear-cut. In fact, some chipsquality to be at least sud-system if not quite completesystem. In many cases, system are built from a mixture ofdiscrete components and integrated circuits.

1.3 Linier and Digital Circuits

Most electronic system are designed to receive anelectrical input and then ‘process’ it so that it producean electrical output capable of doing the required task(which the input could not do without the aid of thesystem). For example, in a record player, the signal fromthe pick up (which cannot operate the loudspeakersdirectly) supplies the input to the amplifier whichproduce an output capable of driving the loudspeakers(fig. 1.3 (a)). Or again, in fig. 1.3 (b) showing anarrangement for counting the umber of packets on a movingconveyor belt in a factory, the electrical signals fromthe photocell (produced when the light from the lampopposite is blocked by the passing packet) provide theinput to the counter which generates an output thatenables the display to record the total count.

(a)

(b)

Pick - amplif loudspeak

inpu

outp

Lamp

photoc counte Display

inpu

outp

lighMovingconvevor

Fig. 1.3

The electronic circuits used in system fall into two maingroups – linier (or analogue) and digital.

Linier circuits are simplifier – type circuitshandling signal which are frequently alectricalrepresentations (i.e. analogue) of quantities, such asspecch and music sounds, that change smoothly over arange of values. This would be so in, for instance, theamplifier of Fig. 1.3 (a), where the output will alsovary continuously and be a more or less exact butamplified copy of the input (Fig. 1.4(a)). The outputchanges in step with the input, or in mathematical terms.There is connection between them, so doubling the inputdoubles the output. Many linier circuits use transistorsas amplifier.+

+signal ‘high’

signal 0 time0 ‘low’

time

- (a)(b)

Digital circuits aresswitching- type circuits handlingsignals which have only one of two values. When there isa change from one value to the other, it happens suddenly( Fig. 1.4(b). while linier circuits are continuous statecircuits, digital circuits are two- state ones, their

inputs and outputs are either ‘high’, i.e. near the valueof the supply, or ‘low’, i.e. near zero. They usetransistors as switches. The counter in fig. 1.3(b) is adigital circuits in which the input from the photocell iseither ‘low’ or ‘high’ depending on whether or not lightis interrupted. Digital circuits carry electrical pulses.

A lamp controlled by a dimmer allows a wide range oflight levels and is a continuous state system. Onecontrolled by an on-off switch is a two-state system; itis either fully alight or it is not alight at all.

Some electronic system contain both linier anddigital circuits.

1.4 Electronic Diagrams

Diagrams are the language of electronics. The ‘letters’of this language are the signs or symbols which representcomponents and the ‘words’ are the groups of symbolswhich form circuit diagram. In Fig. 1.5(a) the symbolsfor a resistors, a capacitors and a transistor are shown.In Fig. 1.5(b) they have

Fig. 1.5 (a)

Resis Capacit transis

C1

C2R1

R2

(b)