Design And Construction Of An Improved Potentiometer

ABSTRACT

This work is on an improved potentiometer. A potentiometer is used to precisely measure the electromotive force, electrical quantities such as voltage, current and resistance. This device consists of a resistive element called the track and a sliding contact called the wiper internally where end terminals are attached to the resistive element. The main aim of this work described the design for constructing inexpensive potentiometer which possesses a practical degree of precision which is used primarily in undergraduate courses. The work was carried out in the school laboratory where all the components used were made available then setup for measurement. At the end of the work, this device was built and was seen responding to its working principle.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• AIM AND OBJECTIVE OF THE PROJECT
• SCOPE OF THE PROJECT
• ADVANTAGES OF POTENTIOMETER
• DISADVANTAGES OF POTENTIOMETER
• RESEARCH QUESTION
• RESEARCH HYPOTHESES
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF A POTENTIOMETER
• HISTORICAL BACKGROUND OF A POTENTIOMETER
• TYPES OF POTENTIOMETERS
• CHARACTERISTICS OF POTENTIOMETER
• DIFFERENCE BETWEEN POTENTIOMETER AND VOLTMETER
• MEASUREMENT OF VOLTAGE BY POTENTIOMETER

CHAPTER THREE

METHODOLOGY

• CIRCUIT DIAGRAM
• CIRCUIT DESCRIPTION
• CONSTRUCTION OF POTENTIOMETER
• SCHEMATIC SYMBOL

CHAPTER FOUR

4.0      TEST AND RESULT ANALYSIS

• CONSTRUCTION PROCEDURE AND TESTING ANALYSIS
• CASING AND PACKAGING
• ASSEMBLING OF SECTIONS
• TESTING OF SYSTEM OPERATION

CHAPTER FIVE

• CONCLUSION
• REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                           BACKGROUND OF THE STUDY

The Potentiometer is described as an electric instrument used to measure the EMF (electromotive force) of a given cell, the internal resistance of a cell. And also it is used to compare the EMFs of different cells. It can also use as a variable resistor in most of applications. These potentiometers are used in huge quantities in the manufacture of electronics equipment that provides a way of adjusting electronic circuits so that the correct outputs are obtained. Although their most obvious use must be for volume controls on radios and other electronic equipment used for audio.

Potentiometers consist of a resistive element, a sliding contact (wiper) that moves along the element, making good electrical contact with one part of it, electrical terminals at each end of the element, a mechanism that moves the wiper from one end to the other, and a housing containing the element and wiper.

Many inexpensive potentiometers are constructed with a resistive element (B in cutaway drawing) formed into an arc of a circle usually a little less than a full turn and a wiper (C) sliding on this element when rotated, making electrical contact. The resistive element can be flat or angled. Each end of the resistive element is connected to a terminal (E, G) on the case. The wiper is connected to a third terminal (F), usually between the other two. On panel potentiometers, the wiper is usually the center terminal of three. For single-turn potentiometers, this wiper typically travels just under one revolution around the contact. The only point of ingress for contamination is the narrow space between the shaft and the housing it rotates in.

Another type is the linear slider potentiometer, which has a wiper which slides along a linear element instead of rotating. Contamination can potentially enter anywhere along the slot the slider moves in, making effective sealing more difficult and compromising long-term reliability. An advantage of the slider potentiometer is that the slider position gives a visual indication of its setting. While the setting of a rotary potentiometer can be seen by the position of a marking on the knob, an array of sliders can give a visual impression of settings as in a graphic equalizer or faders on a mixing console. The main aim of this work is to build an improved and inexpensive potentiometer.

1.2                     AIM AND OBJECTIVES OF THE STUDY

The main aim of this work described the design for constructing inexpensive potentiometer which possesses a practical degree of precision which is used primarily in undergraduate courses. The objectives of the work are:

1. To setup a circuit that will illustrate the principle of potentiometer
2. To measure the emf of electrochemical cells

• To carryout potentiometer titration

1.3                                    SCOPE OF THE STUDY

This work is on a potentiometer which is commonly used in undergraduate laboratories in terms of its application.  This device can be used as a PH meter and also, it can also be used to measure the emf of thermocouples.

1.4                       ADVANTAGES OF POTENTIOMETER

The advantages of potentiometer include the following.

• There is no chance of getting errors because it uses the zero reflection method.
• The standardization can be done by using a normal cell directly
• It is used to measure small emf’s due to highly sensitive
• Based on the requirement, the potentiometer length can be increased to get accuracy.
• When the potentiometer is used in the circuit for measurement then it doesn’t draw any current.
• It is used to measure the inner resistance of a cell as well as compares the e.m.f. of two cells but by using a voltmeter, it is not possible.

1.5                    DISADVANTAGES OF POTENTIOMETER

The disadvantages of potentiometer include the following.

• The potentiometer usage is not convenient
• The cross-section area of potentiometer wire should be consistent so that is not possible practically.
• While doing an experiment, the wire temperature should be stable but this is hard due to the current flow.
• The main drawback of this is, it needs a huge force to move their wiper or sliding contacts. There is erosion because of the movement of the wiper. So it decreases the transducer’s life
• Bandwidth is limited.

1.6                                                   RESEARCH QUESTION

At the end of this work, answers to the following questions shall be made known:

1. How does a Potentiometer work?
2. What are the types of Potentiometers?

• What is the difference between rheostat and potentiometer?

1. What are the applications of Potentiometer?

1.7                                                RESEARCH HYPOTHESES

There is a significant relationship between Potentiometer and voltage

1.8                                     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.