UNIVERSITY OF NAIROBI
COLLEGE OF BIOLOGICAL AND PHYSICAL SCIENCES
FACULTY OF SCIENCE
SPH 307
INTRODUCTORY ELECTRONICS
Dr. Kenneth A. Kaduki
Department of Physics
University of Nairobi
Reviewer: Prof. Bernard O. Aduda
SPH 307
INTRODUCTORY ELECTRONICS
INTRODUCTION
All of us have used electronic equipment of one type or the other. Most of our homes
have radios and, increasingly, television and electronic apparatus of other kinds are being
considered as standard domestic equipment. Mobile phones, personal computers, and CD
players provide further proof that electronics is vital to a developing economy like ours.
This series of ten lectures is intended as an introduction to the exciting field of electronics
for students with no prior knowledge of the technical aspects of the subject.
The primary goal of the lectures is to present the basic principles of operation of
electronic devices and demonstrate their utilization in circuit applications. You will also
be introduced to the analytical tools and techniques required to solve a variety of practical
problems in electronics.
Learning Objectives:
Upon completion of this study unit you should be able to:
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Apply Kirchoff’s laws to electronic circuits and derive the basic
equations
Apply the following fundamental techniques for the analysis of
resistive circuits: superposition theorem; Thevenin’s theorem;
Norton’s theorem.
Describe the basic principles underlying the physics of
semiconductor devices in general and the PN junction in
particular.
Explain the operation of selected diode-based circuits.
Describe the operation of transistors.
Determine and select the operation point of transistors.
Draw transistor amplifier circuits and explain how they work.
Describe the process of Integrated Circuit (IC) manufacture.
Compute the gain of Simple Operational Amplifier–based
amplification circuits.
List the major classes of sensors and explain the principle of
operation of selected sensors.
Describe the principle of operation of various optoelectronic
devices.
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The material is in the following order: I start by presenting Kirchoff’s laws and network
theorems. These two lectures will provide the ‘tools’ you require for the systematic
analysis of a wide range of direct current (dc) circuits. In lecture 3, I present
semiconductor theory, the diode (pn junction) and diode characteristics. Lecture 4
introduces a few basic diode–based circuits. In lectures 5 to 7, I discuss the construction
and characteristics of transistors and show how they can be assembled into basic voltage
amplifiers.
Integrated circuits (ICs) have led to a ‘systems’ approach to electronics. In lecture 8, I
present a brief section on the manufacture of ICs. This is followed by a discussion of the
characteristics and basic applications of the Operational Amplifier (Op Amp) – the most
commonly used linear IC. The last two lectures provide an introduction to transducers
and optoelectronic devices respectively.
I have included a number of questions and exercises after each lecture summary. You
should attempt these questions before advancing to the next lecture. Self–test questions
are also provided at various points of each lecture. You should attempt these questions
before moving on to the material that follows. Answers to the self–test questions are
provided at the end of each lecture.
The text books listed below are useful references for most of the material presented in
this study unit:
1. A. P. Malvino, Electronic Principles, Tata McGraw-Hill Publishing Company Limited,
New Delhi (1999)
2. R. Grob, Basic Electronics, Tata McGraw-Hill Publishing Company Limited, New Delhi
(1997)
Please feel free to point out any errors that you come across as you read these lecture
notes.
Dr. Kenneth Amiga Kaduki
Senior Lecturer, Department of Physics,
Faculty of Science,
University of Nairobi
April 2005
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CONTENT
PAGE
INTRODUCTION
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LECTURE 1: KIRCHOFFS LAWS
1.1
Introduction
1.2
Basic Circuit Elements
1.3
Kirchoff’s Current Law (KCL)
1.4
Kirchoff’s Voltage Law (KVL)
1.5
Method of Branch Currents
1.6
Node–Voltage Analysis
1.7
Method of Mesh Currents
1.8
Summary
1.9
Exercises
1
1
2
5
7
11
15
19
20
LECTURE 2: NETWORK THEOREMS
2.1
Introduction
2.2
Superposition
2.3
Thevenin’s Theorem
2.4
Thevenizing a Circuit with Two Voltage Sources
2.5
Thevenizing a Bridge Circuit
2.6
Norton’s Theorem
2.8
Summary
2.9
Exercises
22
22
25
29
31
33
38
38
LECTURE 3: SEMICONDUCTORS
3.1
Introduction
3.2
Semiconductors
3.3
Electrons and Holes
3.4
Extrinsic Conductivity
3.5
Majority and Minority Carriers
3.6
Compensation
3.7
The pn Junction
3.8
Biased pn Junction
3.9
Avalanche Breakdown
3.10
Summary
3.11
Exercises
40
40
42
43
44
45
45
46
48
52
53
LECTURE 4: DIODE CIRCUITS
4.1
Introduction
4.2
The Half–Wave Rectifier
4.3
The Full–Wave Rectifier
4.4
Waveform Filtering (Smoothing)
4.5
Voltage–Doubler Circuit
4.6
Clippers and Clampers
4.7
Summary
4.8
Exercises
54
54
55
58
62
63
65
65
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5.
6.
7.
8.
9.
BIPOLAR JUNCTION TRANSISTOR (BJT)
5.1
Introduction
5.2
Construction and Symbols of the BJT
5.3
Transistor Action
5.4
Transistor Currents
5.5
The Common Emitter (CE) Characteristics
5.6
Summary
5.7
Exercises
67
67
69
71
73
78
79
VOLTAGE AMPLIFICATION
6.1
Introduction
6.2
Load Resistor
6.3
Working Point and Bias
6.4
Coupling Capacitors
6.5
Stabilizing the Operating Point
6.6
Fully–Stabilized Voltage Amplifier
6.7
Constant–Emitter–Current Bias
6.8
DC Load Line and Collector Bias
6.9
Measurement of the Voltage Gain
6.10
Summary
6.11
Exercises
80
80
81
82
84
86
87
89
93
93
93
FIELD EFFECT TRANSISTOR (FET)
7.1
Introduction
7.2
Construction and Symbols of the JFET
7.3
Terminal Characteristics of the JFET
7.4
Bias Line and Load Line for JFET Amplifier
7.5
Establishing Bounds on Q-Point Location
7.6
Graphical Analysis of JFET Amplifiers
7.7
Transconductance
7.8
Construction and Symbols of the MOSFET
7.9
Terminal Characteristics of the MOSFET
7.10
Summary
7.11
Exercises
95
96
98
101
104
105
106
107
108
110
110
INTEGRATED CIRCUITS
8.1
Introduction
8.2
Manufacture of Integrated Circuits
8.3
Ideal and Practical Operational Amplifiers (Op Amps)
8.4
Op Amp–based Amplification Circuits
8.5
Wein Bridge Oscillator
8.6
Summary
8.7
Exercises
112
112
117
119
125
127
128
TRANSDUCERS
9.1
Introduction
9.2
Classification of Transducers
9.3
Thermistor
9.4
Thermocouple
9.5
Resistance Temperature Detector (RTD)
9.6
The Linear Variable Differential Transformer (LVDT)
130
130
133
135
136
138
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9.7
9.8
9.9
10.
Strain Gauge
Summary
Exercises
139
141
142
OPTOELECTRONIC DEVICES
10.1
Introduction
10.2
Light Sources
10.3
Light Detectors
10.4
Optocouplers
10.5
Summary
10.6
Exercises
144
145
150
152
153
153
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