ABSTRACT

This thesis gives the account for the design and construction of a 45W Audio Power Amplifier with the objective of producing a reliable and cheaper amplifier that can be used in a household or stage.

The Audio Power Amplifier was constructed with electrical/electronics components such as resistors, capacitors, transformer, transistors and so on. Many tools/instruments like soldering iron, multimeter and so on were used.

The 45W Audio Power Amplifier when compared with other types of Audio Power Amplifier of the same rating in the market is cheaper as the  components and materials used were locally sourced and selected to suit the desired purpose and environment.

LIST OF TABLES, GRAPHS AND FIGURES

Figure 1.1 circuit diagram of a 25W Audio Power Amplifier

Figure 2.1 Resistor colour band table

Figure 2.2a Colour code marking on a resistor

Figure 2.2b Circuit symbol of resisitor

Figure 2.3 Circuit symbols of capacitor

Figure 2.4 Diode circuit symbol

Figure 2.5a Formation of potential barrier

Figure 2.5b Forward biasing a P-N junction diode

Figure 2.5c Reverse biasing a P-N junction diode

Figure 2.6a Structure and symbol of p-n-p and n-p-n transistor

Figure 2.6b Biasing of a transistor

Figure 2.7   Structure of an IC

Figure 2.8 JRC 4558IC circuit diagram

Figure 3.1a The power supply circuit diagram

Figure 3.1b Block diagram of a power supply unit

Figure 3.2a The Pre-amplifier circuit diagram

Figure 3.2b The OP-amp audio mixer

Figure 3.3 The tone control circuit

Figure 3.4a A complementary symmetry class B amplifier

Figure 3.4b The output stage of the public address system

Figure 4.1 The circuit layout diagram

Figure 4.2 The body construction diagram (case)

Figure 4.6 Costing table.

TABLE OF CONTENTS

Title page

Dedication

Acknowledgement

Approval page

Abstract

List of tables, graph and figures

Table of contents

CHAPTER ONE

1.1 Introduction

CHAPTER TWO: DESCRIPTION OF CIRCUIT ELEMENT

2.1 Resistors

2.2 Capacitors

2.3 Diodes

2.4 Bipolar Junction Transistor (BJT)

2.5 Integrated Circuits (ICs)

CHAPTER THREE: PRINCIPLE OF OPERATION

3.1 Power supply

3.2 Pre-amplifier

3.3 Tone control

3.4 Power amplifier

CHAPTER FOUR: CONSTRUCTION AND TESTING

4.1 Breadboard/Prototyping

4.2 Circuit layout

4.3 Construction

4.4 Testing and Result

4.5 Packaging

4.6 Costing

CHAPTER FIVE: CONCLUSION/RECOMMENDATION

References