Engineer Rashid Ali

Engineer Rashid Ali    with M. Hamza khan, Laser security System.

Laser Security System by Engineer Rashid Ali

Laser Security System

Definition:

Laser security system is designed to detect intrusion – unauthorized entry – into a building or area. Security alarms are used in residential, commercial, industrial, and military properties for protection against burglary (theft) or property damage, as well as personal protection against intruders.

Working Principle:

A beam of light from laser strikes on LDR. As remains it strikes on LDR, alarm (Buzzer) will remain off. When any object cut off the path of laser light then light will not reach to LDR and Buzzer starts alarming and also LED glows.

Components:

1.    Battery 9v.

2.    Resistance 100 ohm & 6.8k ohm.

3.    LED (Light emitting diode).

4.    Buzzer.

5.    Transistor BT169.

6.    Capacitor 1u farad.

7.    LDR (Light depending resistance).

8.    Wires.

9.    Laser light.

10. (PCB) Vero Board.

Circuit Diagram:

Construction:

Watch video;
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First of all we take a resistance of 100 ohm and connect its one terminal with positive terminal of battery and its other terminal with positive leg of LED. And also a buzzer is connected in parallel combination to resistance & LED. Then the negative leg of LED connected to the emitter of transistor. According to circuit diagram we connect a resistance of 6.8k ohm with positive terminal of battery and with one leg of LDR. Then capacitor is connected in such a way that its positive terminal is connected with base of transistor & also with positive terminal of LDR. Then all of their remaining terminals (collector, capacitor, LDR) connected to the negative terminal of battery. As shown in circuit diagram.

Working:

                A beam of laser light continuously striking on LDR, its resistance remains unchanged. Required voltage (3v) could not reach the buzzer & LDR so it remains off. But Whenever, any object cuts its path, laser light could not reach the LDR as a result, resistance of LDR is changed (increases) and a voltage greater than 3v is supplied to buzzer and it starts alarming, a red LED glows up as well. Here transistor acts as a switch. It controls the voltage supplied to buzzer & LED and capacitor is used to store the charges.

          In this way any theft or unwanted object is detected easily. Buzzer keeps on alarming until we turn off power button.

Applications:

·      Laser security system is one of the advanced security systems used almost everywhere.

·      Use in banks , expensive jewelry shop, residential areas,  military, offices & homes.  

Advantages:

·       Easily available components.

·       Simple in construction.

·       Cheap.