CONSTRUCTION OF A LIGHT SENSITIVE ALARM

CHAPTER ONE

INTRODUCTION

The light sensitive alarm is an electronic circuit that detects a sudden shadow falling on the light sensor and sounds the bleeper. When this happens, the circuit will respond to gradual charges in brightness to avoid false alarm. The beeper sounds for only a short time to prevent the battery from running flat. Normal light can be use. The circuit will work best if a beam of light is made to fall on the light sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is a light dependent resistor (LDR); this has a low resistance in bright light and a high resistance in dim light. The light sensitivity of the circuit can be adjusted by varying the 100kiloohms (K) preset. The length of bleep can be varied from 0.5 to 10 seconds using 1 milliohm (M) preset. using the 7555 low power timer ensures that the circuit draws very little current of about 0.5 milli-Amps except for the short time when the bleeper is sounding, this uses 7 milli-Amps. If the circuit is switch on continuously, an alkaline 9V battery should last for about a month.

AIMS AND OBJECTIVES

The project is actually designed to promote high level of security in workshops, industries and home. It enhances a recorded indication of visitors and to summon staff or personnel to fulfill a service as in domestic and industrial use.

PURPOSE OF THE STUDY

The purpose of this study is to provide maximum security round the world.

SCOPE OF THE STUDY

This project “light sensitive alarm” is design mainly to alert the user by a bleeper when the circuit detects a sudden shadow falling on the light sensor the bleeper duration can be controlled by varyingthe I ohms – preset resistor.

LIMITATION OF THE STUDY

Thelimitations of this study are: the bleeper sound for only a short time to prevent the battery from running flat. If there is any little mistake during soldering, there will not work well. Also by met being able to purchase some components and their exact value couple with transportation problems has also gone a long way to reduce the efficiency of this project.

SIGNIFICANCE OF THE PROJECT

This project helps to provide security in offices, hotels, homes etc. it also promotes and encourage researches involving in security research projects.