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PROJECT TOPIC:  DESIGN AND CONSTRUCTION OF A 0-24V VARIABLE REGULATED POWER SUPPLY
Department:  Electrical Electronics
AMOUNT:  10,000
FORMAT:   MS WORD
PAGES:  87
 
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CHAPTER ONE

INTRODUCTION

1.1   BACKGROUND OF THE STUDY

A power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are sometimes referred to as electric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads.

Every power supply must obtain the energy it supplies to its load, as well as any energy it consumes while performing that task, from an energy source. Depending on its design, a power supply may obtain energy from various types of energy sources, including electrical energy transmission systems, energy storage devices such as a batteries and fuel cells, electromechanical systems such as generators and alternators, solar power converters, or another power supply.

All power supplies have a power input, which receives energy from the energy source, and a power output that delivers energy to the load. In most power supplies the power input and output consist of electrical connectors or hardwired circuit connections, though some power supplies employ wireless energy transfer in lieu of galvanic connections for the power input or output. Some power supplies have other types of inputs and outputs as well, for functions such as external monitoring and control.To obtain a complete circuit for this work, the circuit is mainly composed of the:

Input transformer:   The input transformer is used to transform the incoming line voltage down to the required level for the power supply. Typically the input transformer provides a step down function. It also isolates the output circuit from the line supply.

Rectifier:   The power supply rectifier converts the incoming signal from an AC format into raw DC. Either half wave or more commonly full wave rectifiers may be used as they make use of both halves of the incoming AC signal.

Smoothing:   The raw DC from the rectifier is far from constant falling to zero when the AC waveform crossed the zero axis, and then rising to its peak. The addition of a reservoir capacitor here fills in the troughs in the waveform, enabling the next stage of the power supply to operate. Large value capacitors are normally used within this stage.

Voltage adjuster:   This stage of the power supply takes the smoothed voltage and uses a variable ic and potentiometer to provide a variable regulated output virtually regardless of the output current and any minor fluctuations in the input level.

1.2   PROBLEM STATEMENT

For prototyping and hobbyists, appliances or gadget with smaller voltages, they normally use batteries as a reliable power source. Instead of using batteries, which have a limited lifetime and which is also cost effective, a variable DC power supply can be used which is implemented in this project.

1.3    AIM OF THE PROJECT

The aim of any power supply is to provide the required power to the load using an AC supply at the input. But for variable regulated power supply of 0 – 24v is to design a power supply with one output terminal with variable output voltage, and the output is gotten by turning the voltage adjuster known as the potentiometer.

 

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