Description
ABSTRACT
The well known and old method of testing a zener diode is to set up a power supply and voltmeter, select a series resistor to limit current, and measure the voltage for each diode. Alternatives like reading the part number and looking it up, or setting up a curve tracer aren’t any faster. Many errors, burned out diodes, and damaged projects are always occur during this process. To overcome this challenges this simple circuit was built displays the breakdown voltage of a zener diode by using a 555 timer and 3 terminal digital voltmeter as the major components of the device.
TABLE OF CONTENTS
COVER PAGE
TITLE PAGE
APPROVAL PAGE
DEDICATION
ACKNOWELDGEMENT
ABSTRACT
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE PROJECT
- PROBLEM STATEMENT
- AIM OF THE PROJECT
- OBJECTIVE OF THE PROJECT
- PURPOSE OF THE PROJECT
- SCOPE OF THE PROJECT
- SIGNIFICANCE OF THE PROJECT
- APPLICATION OF THE PROJECT
- PROJECT ORGANISATION
CHAPTER TWO
LITERATURE REVIEW
- OVERVIEW OF A ZENER DIODE
- OPERATION OF ZENER DIODE
- ZENER DIODES CONSTRUCTION
CHAPTER THREE
3.0 CONSTRUCTION METHODOLOGY
3.1 BLOCK DIAGRAM
3.2 CIRCUIT DIAGRAM
3.3 PARTS LIST
3.4 SYSTEM OPERATION
3.5 CIRCUIT DESCRIPTION
3.6 DESIGN NOTE
3.7 DESCRIPTION OF COMPONENTS USED
CHAPTER FOUR
4.0 TEST AND RESULT ANALYSIS
- CONSTRUCTION PROCEDURE AND TESTING
- CASING AND PACKAGING
- ASSEMBLING OF SECTIONS
- TESTING OF SYSTEM OPERATION
- BILL OF ENGINEERING MEASUREMENTS AND EVALUATION
CHAPTER FIVE
- CONCLUSION
- RECOMMENDATION
- REFERENCES
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE PROJECT
A Zener diode is a type of diode that allows current to flow not only from its anode to its cathode, but also in the reverse direction, when the Zener voltage is reached.
Zener diodes have a highly doped p–n junction. Normal diodes break down with a reverse voltage, but the voltage and sharpness of the knee are not as well defined as for a Zener diode. Normal diodes are not designed to operate in the breakdown region, whereas Zener diodes operate reliably in this region.
The device was named after Clarence Melvin Zener, who discovered the Zener effect. Zener reverse breakdown is due to electron quantum tunnelling caused by a high-strength electric field. However, many diodes described as “Zener” diodes rely instead on avalanche breakdown. Both breakdown types are used in Zener diodes with the Zener effect predominating at lower voltages and avalanche breakdown at higher voltages.
Zener diodes are widely used in electronic equipment of all kinds and are one of the basic building blocks of electronic circuits. They are used to generate low-power stabilized supply rails from a higher voltage and to provide reference voltages for circuits, especially stabilized power supplies. They are also used to protect circuits from overvoltage, especially electrostatic discharge (ESD). In a circuit zener diode can fail due to aging, or low value of current limiting resistor which exposes the device to over-heating and later got burnt.
When a zener diode is gotten from a cabinet which contains many zener diodes, one always want to check its breakdown voltage before using it in a project — just to be sure that one is using the correct value of diode. This procedure needs to be repeated when putting unused diodes back into cabinet, or when sorting among a bunch of diodes. A zener diode tester is used to measure the breakdown voltage of a zener diode [1][2][3].
1.1 PROBLEM STATEMENT
The zener diode is a specialized silicon diode that looks like a normal silicon diode in the forward direction. However, in the reverse voltage direction, it exhibits a low leakage current like a normal diode until a voltage — the so-called “zener voltage” — is reached. At that point, it sharply exhibits a controlled constant breakdown voltage which cannot be measure or test using multimeter most expecially when it was mixed up with other diodes that have the same colour with zener diodes, it becomes difficult to know the zener diode despite the fact that the rated breakdown voltage writing on the body is always small to be read with ordinary eye unless by using microscope even when the zener is gotten from a box mixed with zener although, there is need to know the breakdown voltage before using it in a circuit. However this device makes it easier to test a zener diode in other to read the breakdown voltage [4][6].
1.2 AIM OF THE PROJECT
The main aim of this work is to build a device that can easily and accurately used to read the breakdown voltage of a zener diode.
1.3 OBJECTIVE OF THE STUDY
At the end of this work you will be able to:
- Build the device
- Know the working principle of the tester
- Understand the working and application of a zener diode tester
- Describe how a zener diode can be used with a current limiting resistor to form a simple regulated voltage supply.
- How to read zener diode breakdown voltages using this device.
1.4 SIGNIFICANCE OF THE PROJECT
It’s time consuming to set up a power supply and voltmeter, select a series resistor to limit current, and measure the voltage for each diode when zener diodes are picked for a circuit. Alternatives like reading the part number and looking it up, or setting up a curve tracer aren’t any faster. Many errors, burned out diodes, and damaged projects will occur. This work provides a fast, reliable, low cost of measuring the breakdown voltage of zener diodes. With this device, There’s no need to select a current-limiting resistor. Just connect a zener diode and digital volt meter (DVM) and measure its breakdown voltage at a consistent and safe power level.
1.5 APPLICATION OF THE PROJECT
This device is used to test zener diode’s breakdown voltage. The circuit will also safely test LEDs — including white LEDs that multimeters can’t test and other low voltage diodes in their forward direction, as well as MOVs (metal-oxide varistors) and other protective devices with higher voltage breakdowns.
1.6 PURPOSE OF THE PROJECT
The main purpose of this work is to provide a fast and reliable means of testing zener diodes breakdown voltages.
1.7 SCOPE OF THE PROJECT
The tester described in this work is a simple two-transistor circuit operating from a 9V battery which tests zener diodes with breakdown voltages up to 30 volts. Nothing more than a multimeter is necessary to build, test, and use the circuit. Its transformer-coupled design adjusts the output voltage automatically to the voltage of the zener diode under test, while adjusting diode current to preserve a relatively constant diode power throughout the measurement range [3][4].
1.8 RESEARCH QUESTION
What is the working principle of Zener diode?
How does zener diode work as voltage regulator?
What is the value of Zener voltage for given zener diode?
Why zener diode is used in reverse bias?
1.9 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.
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