Design And Construction Of Power Amplifier

Project and Seminar Material For Electrical Electronics Engineering EEE

Chapter One

Introduction

Power amplifier is an electronic device, which is used to increase sound energy. In other words, the final stage which must driven a given load e.g mechanical indicator, a loudspeaker cathode roy tade, magnetic deflection coil, a transmitting accrual of a communication network. Power amplifier is also used in regulation power supplies, chopper amplifier, motor controller etc. In general the load will by its nature, demand a certain power from the amplifier and the out stage must be capable of delivering the power (large current or voltage swing). The preceding stage to the power stage are supposed to given the input to drive the power stage so that it can produce the load requirement.

In power amplifier a large portion of active device (transistor) characteristics is used (i.e there is large alternating input voltage or current to make efficient use of the device.

The economic importance of power amplifier is know to be useful in many aspect of both social and business activities. In the social activity, it is found that during occasions like public gathering and parties people us power amplifier to increase or enlarge their speech as to be audible. While the business activity: during business promotion, it is found that marketing agents use power amplifier for their advertisement: for notifying the public about combating.

General Description

The project is a 50 volts, 150 w Audio – power amplifier. It is capable of producing a maximum watts (output) per channel. When in full operation it will generate a maximum power output of cow. The system is design to deliver optimum performance and reliability for house application.
The external features is shown in fig (ii)

Is the volume control
Is the tone control?
Is the input sector?
Is the power switch?
Is the power indicator?
Is the output source?
Is the input source?
Is the A.C cord for the A.C power input?

The Internal Features

The system is made up of four-(4) circuit brought together to work as a unit

The four circuits are:

The pre- amplifier stage
The control stage
The power amplifier stage
The power supply stage

Sequence of Operation

Plug the a-c coil to a-c source of 220 to 220v
Connect the input source to the output of cassette player or radio.
Connect two speakers, one to each side (ground) not any of the outputs)
Turn the volume control to minimum
Turn on the cassette player or radio connected
Switch on the power switch of the amplifier
Then raise the volume to desired level and use the tone control (Bass and treble) to control the tone.

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