Thursday, 19 May 2016

Design And Construction of an Automatic Security Light

This project is the design and construction of an automatic security light using the locally available materials with an LDR (Light Dependent Resistor) as the main component serving as the photo-sensor which converts light energy into electrical signal. Two test were carried out on the completed work. A continuity test for the circuit gave a positive output. Sensitivity test for the LDR was carried out in two different conditions; when the night falls, the security light automatically turns ON and the light remains on until the LDR detects a day light. The test for sensitivity also carried out during the day time using three different materials: Opaque, Transparent and Translucent. The opaque materials used are; bear hand, a book, a file and a hand bag which gave positive result within the distance range of 13cm-3cm with voltage across the LDR within the range of 4.1V-6.2V. The other two materials (i.e. Transparent and Translucent) appeared to be negative.        


Title page


Approval page




Table of content 

List of figures 

Chapter One

1.0     Introduction

1.1     Block Diagram

1.2     Aims and objectives

1.3     Justification

1.4     Scope of work

Chapter Two      

2.0     Literature Review

2.1     Photo resistor

2.1.1  Cadmium sulphide cells

2.1.2  Applications of photo a resistors     

2.2     Photodiode

2.2.1  Quick reference guide

2.2.2  Principle of operation of a photodiode

2.2.3  Other modes of operation of a photodiode

2.2.4  Materials used to make a photodiode

2.2.5  Features of a photodiode

2.2.6  Applications of a photodiode  

2.3     Comparism with Photomultipliers

2.3.1  Advantages compared to photomultipliers

2.3.2  Disadvantages compared to photomultipliers

2.4     Avalanche photodiode

2.4.1  Applications of Avalanche photodiode

2.4.2  Materials that are used to make the avalanche photodiode

2.5     Review of circuit components

2.5.1  LM358

2.5.2  Transistor

2.5.3 Advantages of transistors over vacuum tubes      

2.5.4  Diode

2.5.5  Capacitor

2.5.6  Voltage regulator

2.5.7  Relays

2.5.8 merits of relays

Chapter Three

3.0     Circuit Design and Construction

3.1     Circuit Diagram

3.2     Principle of operation

3.3     Design Analysis

3.3.1  Power supply

3.3.2  Signal amplifier circuit   

3.4     The electromechanical relay circuit

3.5     Circuit construction

3.6     Packaging

Chapter Four     

4.0     Test and Result

4.1     Test and Result of the automatic security light 

Chapter Five

5.0     Discussion, Recommendation and Conclusion

5.1     Discussion     

5.2     Conclusion
5.3     Recommendation



           1.0     INTRODUCTION

In the field of physical security, security lighting is often used as a preventive and corrective measure against intrusions or other criminal activity on a physical piece of property. Security lighting may be provided to aid in the detection of intruders, to deter intruders, or in some cases simply to increase the feeling of safety. Lighting is integral to crime prevention through environmental design (Palz and Wolfgang, 2010).

Security lighting can be used in residential, commercial, industrial, institutional, and military settings. Some examples of security lighting include floodlights and low pressure sodium vapour lights. Most lights intended to be left on all night are high-intensity discharge lamps as these have good energy efficiency, thus reducing the cost of running a lamp for such long periods (Barry, 2003).

Security lighting may be subject to vandalism, possibly to reduce its effectiveness for a subsequent intrusion attempt. Thus security lights should either be mounted very high, or else protected by wire mesh or tough polycarbonate shields. Other lamps may be completely recessed from view and access, with the light directed out through a light pipe or reflected from a polished aluminium or stainless steel mirror. For similar reasons high security installations may provide a stand-by power supply and automatic switching units for their security lighting ( 

Modern security lights may be activated by sensors such as passive infrared sensors (PIRs), turning on only when a person (or other mammal) approaches. PIR activated lamps will usually be incandescent bulbs so that they can activate instantly. PIR sensor activation can increase both the deterrent effect (since the intruder knows that he has been detected) and the detection effect (since a person will be attracted to the sudden increase in light). Another good design is the implementation of an automatic switching system which uses photocells so that the lamps only turn on when it is dark (Gowar and John, 1993).


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