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DESIGN AND CONSTRUCTION OF 60 WATTS POWER AMPLIFIER

ABSTRACT

An audio AMP is basically a system which is used as a means of increasing the level of sound or audio signals for maximum use. A public address system consists basically of microphone, Amplifier and speaker(s) to facilitate the communication to intelligible speech to groups of people or an audience. The main purpose of providing sound reinforcement indoors with sufficient high – fidelity being the coverage of large groups with unobstructive sound system. Directional horns are often employed in outdoor systems to concentrate sound energy efficiently over the areas served. Intelligibility may be the performance criteria for an indoor system such as an air waiting room. On the other hand, high fidelity reproduction is required for sound reinforcement system for instance, a conference hall, or a class room. Most power amplifiers of a public address system have provisions for one or more microphones and one or other sound sources such as FM, AM radio tuner output, tape recorder and record player generally tagged auxiliary sound sources. Level traders or volume contracts are provided to adjust the volume of each of those sources independently. In this project, the concentration of a high fidelity (H1 – F1) power amplifier for the in public address system. This amplifier is designed as a unit utilizing three input sources. Operating controls are provided for each input source with the possibility of mixing the three input sources depending on the setting of the operating or gain controls. This flexibility of mixer operation is without sudden increase or decrease in volume.

CHAPTER ONE

INTORDUCTION

1.1 BACKGROUND OF THE STUDY

A public address system (PA system) is an electronic sound amplification and distribution system with a microphone, amplifier and loudspeakers, used to allow a person to address a large public, for example for announcements of movements at large and noisy air and rail terminals. The term is also used for systems which may additionally have a mixing console, and amplifiers and loudspeakers suitable for music as well as speech, used to reinforce a sound source, such as recorded music or a person giving a speech or distributing the sound throughout a venue or building. Simple PA systems are often used in small venues such as school auditoriums, churches, and small bars.

PA systems with many speakers are widely used to make announcements in public, institutional and commercial buildings and locations. Intercom systems, installed in many buildings, have microphones in many rooms allowing the occupants to respond to announcements. Sound reinforcement systems and PA systems may use some similar components, but with differing application, although the distinction between the two is not clear-cut. Sound reinforcement systems are for live music or performance, whereas PA systems are primarily for reproduction of speech. Public address systems consist of input sources, amplifiers, control and monitoring equipment, and loudspeakers.

The primary input sources are microphones for live announcements and a source of recorded sound. There may be a system which allows operators, or automated equipment, to select from a number of standard prerecorded messages. These input sources are fed into preamplifiers and signal routers that determine the zones to which the audio signal is fed. The preamplified signals are then passed into the amplifiers. Depending on local practices these amplifiers will usually amplify the audio signals to speaker line level. Control equipment monitors the amplifiers and speaker lines for faults before it reaches the loudspeakers. This control equipment is also used for separating zones in a PA system. The loudspeaker is used to convert electrical signals into sound.

1.2 STATEMENT OF THE PROBLEM

This project provides techniques for providing information to audience either at home, office, and restaurant or in the public place since it is a mobile system etc. This project obscured the use of band, bell and shouting as ancient form of communication. As civilization developed the distinction between active and passive communication was rested on the same project.

1.3 AIM AND OBJECTIVES

The aim of this project is to design and construct an audio amplifier system with minimized effect that is normally associated with the output of an amplifier such as noise, distortion, interference and signal to noise ratio, also incorporated with a wireless system which makes it mobile. The system has the ability to amplify weak signals of acoustic sound to a form that can go a long way in solving most of our daily problems arising from communication of high signal. Some PA systems have speakers that cover an entire campus of a college or industrial site, or an entire outdoor complex (e.g., an athletic stadium). A large PA system may also be used as an alert system during an emergency.

The objective through which the aim of design and construction of public address system are as follows:

1.    To Design pre audio amplifier

2.    To Design power amplifier

3.    To Design power supply

4.    To Design RF receiver

5.    To Design tone control

6.    To construct casing

7.    To test                                             

1.4 Significance of the Study

This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.

1.5     Scope of the Study

This study is on the design and construction of 60watts power amplifier

1.6     Limitations of the study

Financial constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).

Time constraint: The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work.