Project

CERTIFICATION

This is to certify that the design and construction of this project was undertaken by AJANI OLAWALE LUQMAN with matriculation number EEE/--/----, of the Department of Electrical and Electronics Engineering of the Federal University of Technology Akure, Ondo State.

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Dr. V.S.A Adeloye                                                                            Dr. A.O. Melodi

Project Supervisor                                                                               Head of Department

DEDICATION

This page is dedicated to my parent, Mr & Mrs Ajani Abiola for their physical, moral and financial support during the course of this project.

ACKNOWLEDGEMENT

All praise is due to Allah; the Creator of the heavens and the earth and all that is in between. I pray He showers His blessing on the Prophet Mohammed (May His Peace and Blessings be upon him), his household, companions and those who follow their path till the time the Hour will be established

Also, worth mentioning are my distinguished supervisor Dr V.S.A Adeloye, my beloved parent, Mr and Mrs Ajani Abiola, Mr Ajani S.A,whom God has used .

Thank you very much for your contribution towards my project and academic pursuit.

           

TABLE OF CONTENTS

TITLE                                                                                                                            PAGES

Title page                                                                                                                                  i

Certification                                                                                                                              ii                                                

Dedication                                                                                                                                iii                             

Acknowledgement                                                                                                                   iv                        

Abstract                                                                                                                                    v                         

Table of contents                                                                                                                     vi                     

Lists of figures                                                                                                                         x     

List of table                                                                                                                             xi                    

Chapter One                                                                                                                                                          

1.1     Introduction                                                                                                                   1          

1.2     Amplifiers                                                                                                                     2

1.3     The Mixer                                                                                                                      3

1.4     The Scope and limitation of the Project                                                                        3

1.5     The Aim and Objectives of the Project                                                                         4

1.6     The Justification for the Project                                                                                    4

Chapter Two                                                                                                                                     

2.0     Literature Review                                                                                                          5

2.1     Background                                                                                                                   5 

2.2    Further Developments in Amplifier Design                                                                  6 

2.3     A Simple Amplifier                                                                                                       6

          2.3.1     Input Impedance                                                                                               8

          2.3.2     Output Impedance                                                                                            8

          2.3.3     Feed Back                                                                                                         8

          2.3.4     Signal Inversion                                                                                                9

2.4     Types of Amplifying Devices                                                                                        9  

           2.4.1     The Vacuum tubes                                                                                           10       

          2.4.2     Bipolar Junction Transistors                                                                             11

          2.4.3     Field effect Transistors                                                                                     12

2.5       Bipolar Junction Transistor (BJT) Action                                                                  13

        2.5.1     Biasing Transistor                                                                                               13     

         2.5.2     Configuration of Transistor                                                                               14

2.6    Classes of Amplifier                                                                                                       16

          2.6.1    Class A                                                                                                              16  

          2.6.2    Class B                                                                                                              18   

          2.6.3    Class AB                                                                                                           19

          2.6.4    Class C                                                                                                              21

          2.6.5     Class D                                                                                                             21

2.7     Operational Amplifier                                                                                                   22

          2.7.1    Type of Operational Amplifier                                                                          24

          2.7.2   Inverting and Non-inverting Op-amp                                                                 25

         2.7.3    Applications of Operational Amplifier                                                               26

         2.8    Loudspeakers                                                                                                         26

         2.8.1     Parts of speaker                                                                                                  26

2.9    Audio Mixers                                                                                                                 27

2.9.1    Audio Power Amplifier                                                                                             27

2.1.0    Microphone Amplification                                                                                         28

2.11     Volume Control of a Typical Amplifier                                                                     28

2.12     Buffer Stage                                                                                                               29

2.13     Mixer Stage                                                                                                                30

2.14     Tone Control                                                                                                               31

2.15     Master Volume Control                                                                                              32

2.16     Power Amplification                                                                                                  32

2.17     Input Stage                                                                                                                 33

            2.17.1  Elimination of 2^nd harmonic distortion                                                           34

            2.17.2  Reducing Linearity                                                                                         35

            2.17.3  Negative Feedback                                                                                         36

2.18     Voltage Amplification Stage                                                                                      37

2.19     Output Stage                                                                                                              40

Chapter Three

3.0    Materials and Methodology                                                                                          41

3.1    Introduction                                                                                                                   41

3.2    The Power supply Stage                                                                                                41

3.3    Pre-Amplification and Tone Control Stage                                                                   43

3.4    The Power Amplification Stage                                                                                    45

3.5     Testing and Observation                                                                                               51

3.6     Casing Construction                                                                                                     52

            3.6.1    Common Types of Amplifier Casing                                                              52                                                                                    

            3.6.2    Screwing the Board to the Perspex                                                                54

            3.6.3    Casing Parts                                                                                                    54

Chapter Four

4.0       Result                                                                                                                          55

4.1       Result                                                                                                                          55

            4.1.1   Output Stage                                                                                                   56

Chapter Five

5.0       Conclusion and Recommendation                                                                              57

5.1        Conclusion                                                                                                                 57

5.2       Recommendation                                                                                                        58

Refrences                                                                                                                               59

LIST OF FIGURES

FIGURE                                                                                                                           PAGE

Fig.2.1       A simple Amplifier circuit                                                                                    7

Fig.2.2       Common Emitter configuration                                                                           14

Fig.2.3       Common Base Configuration mode                                                                     15

Fig.2.4       Common Collector Configuration mode                                                              16

Fig.2.5       Class A Amplifier                                                                                                 17

Fig.2.6       Class B Amplifier                                                                                                 18

Fig.2.7       Class AB Amplifier                                                                                              20

Fig.2.8       Class C Amplifier                                                                                                 21

Fig.2.9       A Typical Op-Amp Configuration                                                                       23

Fig.2.10     A Typical Operational Amplifier                                                                          24

Fig. 2.11    An Op-Amp in the Inverting Configuration                                                        25

Fig.2.12     An Op-Amp in the non-inverting Configuration                                                 26

Fig. 2.13    A Simple 1watt Audio Amplifier                                                                         27

Fig. 2.14    Potential divider biasing                                                                                       28

Fig. 2.15    Emitter Follower (Buffer)                                                                                    29

Fig. 2.16    Improved Buffer Circuit                                                                                      30

Fig. 2.17     A typical Mixer Circuit                                                                                       30

Fig. 2.18     Mixer Circuit                                                                                                       31

Fig. 2.19     A typical Tone Control Circuit                                                                            31

Fig. 2.20     Master Volume Control                                                                                       32

Fig. 2.21     Block Diagram of Power Amplification                                                             32

Fig. 2.22     Circuit Diagram of an Input Differential Pair                                                     33

Fig. 2.23     Constant current source. V_b is kept constant by D1                                            34

Fig. 2.24     Constant current source                                                                                       34

Fig. 2.25     Current Mirror                                                                                                     35

Fig. 2.26     Improved Input Stage                                                                                         35

Fig. 2.27     Potential divider                                                                                                  36

Fig. 2.28    Voltage Amplification stage                                                                                37

Fig. 2.29    VAS with elimination of loading effect                                                              38

Fig. 2.30    Constant Current Source                                                                                      38

Fig. 2.31     Improved VAS                                                                                                    39

Fig.3.1         A Picture showing the Project                                                                            42

Fig.3.2         Circuit diagram for the Pre-Amp Stage used for this Project                            44

Fig. 3.3         A Typical three-Stage Architecture                                                                   47

Fig. 3.4        Circuit Diagram Showing the Schematics diagram of JRC 4458                      49

Fig.3.5         Circuit Diagram Showing the Schematics diagram of the Project                    50

Fig. 3.6        The complete circuit placed inside Perspex                                                       52

Fig. 3.7         Pictures of the Amplifier on Completion                                                          53       

LIST OF TABLE

TABLE                                                                                                                           Page

Table 3.1           Showing the components used                                                              45

ABSTRACT

Audio amplifiers are devices that increase the gain of an audio signal, dominate modern audio technologies. In this project, I will design and build an audio amplifier from scratch and using a JRC4558 as the pre-amplifier to demonstrate that such a key electronic device can be constructed using basic electrical and electronics engineering principles.

After performing major circuit calculations, I modelled the circuit in proteus, which is the computer software that analyses electrical circuits. In particular, I studied the variance that using budget electrical components introduced into the circuit.