Design And Construction Of A 35 Watts Audio Stereo Amplifier

The design and construction of a 35 watts audio amplifier was carried out in this project. The amplifier was designed and constructed successfully using transistor as the major component for voltage amplification. An input voltage of +15v and -15v from a dual power supply was used as input and the result obtained shows that the output was increased by 40% of the input voltage.

TABLE OF CONTENTS

Title Page

Approval Page

Dedication

Acknowledgement

Abstract

Table of Content

CHAPTER ONE: INTRODUCTION

1.0       Background of the study

1.1       Objective of the project

1.2       Problem statement

1.3     Application of the project

1.4       Purpose of the project

1.5       Significance of the project

1.6       limitation of the project

1.7       Project organization

CHAPTER TWO: LITERATURE REVIEW

2.1     Historical background of an amplifier

2.2   Review of classification of power amplifiers

2.3     Classification according to mode of operation

2.4     Review of transistor biasing

CHAPTER THREE: DESIGN AND CONSTRUCTION

3.1     Block diagram of an audio power amplifier

3.2     Circuit diagram of a 35w amplifier

3.3     Circuit operation

3.4     Circuit description

3.5     Power supply circuit

3.6     Parts list of 100 watt amplifier circuit

3.7       Description of components used

CHAPTER FOUR: RESULT ANALYSIS

4.0       Construction Procedure and Testing

4.1       Casing and Packaging

4.2       Assembling of Sections

4.3       Testing of System Operation

4.4     Cost Analysis

CHAPTER FIVE

5.1       Conclusion

5.2       Recommendation

5.3       References

• INTRODUCTION

1.1                                               BACKGROUND OF STUDY

An audio amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 – 20 000 Hz, the human range of hearing) to a level suitable for driving loudspeakers. It is the final electronic stage in a typical audio playback) chain (Matti Otala, 2010).

Audio stereo power amplifier is design to deliver power to the load (speaker), is the product of the voltage and current applied to the load with the output signal power being greater than the input signal power. In other words, a power amplifier amplifies the power of the input signal which is why these types of amplifier circuits are used in audio amplifier output stages to drive loudspeakers (Matti Otala, 2010).

The power amplifier works on the basic principle of converting the DC power drawn from the power supply into an AC voltage signal delivered to the load. Although the amplification is high the efficiency of the conversion from the DC power supply input to the AC voltage signal output is usually poor (Petri-Larmi, M. & Otala, M, 2018).

The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification (this is particularly associated with record turntable signals), equalization, tone controls, mixing/effects, or audio sources like record players, CD players, and cassette players. Most audio power amplifiers require these low-level inputs to adhere to line levels (Joseph B, 2010).

While the input signal to an audio power amplifier may measure only a few hundred microwatts, its output may be tens or hundreds of watts for a home system or thousands or tens of thousands of watts for a concert sound reinforcement system.

Not all amplifiers are the same and are therefore classified according to their circuit configurations and methods of operation. In “Electronics”, small signal amplifiers are commonly used devices as they have the ability to amplify a relatively small input signal, for example from a Sensor such as a photo-device, into a much larger output signal to drive a relay, lamp or loudspeaker for example (Lee, Thomas, 2014).

There are many forms of electronic circuits classed as amplifiers, from Operational Amplifiers and Small Signal Amplifiers up to Large Signal and Power Amplifiers. The classification of an amplifier depends upon the size of the signal, large or small, its physical configuration and how it processes the input signal, which is the relationship between input signal and current flowing in the load (Lee, Thomas, 2014).

• STATEMENT OF THE PROBLEM

• Addressing crowd used to be difficult, this lead to shouting on top of our voice which lead to loss of voice.
• Sometimes, we desired to play out little audio devices (such as cell phone, DVD, TV, etc) in a way that it can be heard by people from a distance.

In other to bring solution to this problem, an amplifier is used to amplify small audio signal to a level it can be heard from a distance. An audio amplifier is one kind of electronic device, used to increase the amplitude of audio signals that permit it. This type of amplifier increases low-power audio signals to a level which is apt for making loudspeakers.

1.3                                                   AIM OF THE PROJECT

The main aim of this project is to design and construct a 35 watts audio amplifier using TDA2030L as the heart of the circuit.

1.3                                           OBJECTIVE OF THE PROJECT

The objectives of this project are:

• To build a low cost audio amplifier
• To become familiar with TDA2030L
• Test the audio amplifier

1.4                                          APPLICATION OF THE PROJECT

Important applications include public address systems, theatrical and concert sound reinforcement systems, and domestic systems such as a stereo or home-theatre system. Instrument amplifiers including guitar amplifiers and electric keyboard amplifiers also use audio power amplifiers. In some cases, the power amplifier for an instrument is integrated into a single amplifier “head” which contains a preamplifier, tone controls, and electronic effects. In other cases, musicians may create a setup with separate rack mount preamplifiers, equalizers, and a power amplifier in a separate chassis (Joseph B, 2010).

1.6                                              PURPOSE OF THE PROJECT

Amplifier’s main purpose is to take the weak signal and make it strong to drive a speaker. The stereo power amplifiers usually get necessary amplification energy of input signals from the AC supply.

1.7                                        SIGNIFICANCE OF THE PROJECT

Today there are many categories of amplifiers used for multifarious purposes. In simple terms an amplifier picks up a weak signal and converts it into a strong one. It is widely used in several devices to boost electrical signals. Radios, televisions and telephones are a few examples to point out in this regard. There are innumerable other applications of amplifiers and it is not easy to enumerate all of them. Some of the common types of amplifiers are used in electronic gadgets and audio systems. These are also used in musical instruments and guitars (Joseph B, 2010).

1.8                                          LIMITATION OF THE PROJECT

As we all know that no human effort to achieve a set of goals goes without difficulties, certain constraints were encountered in the course of carrying out this project and they are as follows:-

1. Difficulty in information collection: I found it too difficult in laying hands of useful information regarding this work and this course me to visit different libraries and internet for solution.
2. Difficulty in parts gathering: I found it too difficult when gathering electronics parts used for the prototype.

• Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information, in the process of data collection (internet) and in assembling of electronics parts used.

1.9                                                  RESEARCH METHODOLOGY

In the course of carrying this study, numerous sources were used which most of them are by visiting libraries, consulting journal and news papers and online research which Google was the major source that was used.

1.10                                    PROJECT ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.