Laser Security System

Comment errors or corrections found for this circuit, and get the chance to win big! You can find our comments section at the end of this page.

This project powered using a mobile charger which gives 6volts and 500mA. It can also powered using battery ranging 6volts. In this 2x5v relays are used. There is a simple password setup using SPDT { single pole double throw} switch. Wiring the password setup needs some knowledge about SPDT switch.

Here I have wired in a such a way that the password is UP,DOWN,UP,DOWN. Here there are 16 possibilities. If you use centre positioned then there are 64 such possibilities. If the position of the switch is set correctly then the security can be disabled.



Firstly, setup the circuit leaving the LDR{ light dependent resitor} out for the laser beam to be focused. power it up. Now the alam will be blown press the reset switch once. The alarm sound will be stopped. Once the beam of laser is crossed the alarm sound will start blowing and continuous until the push button{ RESET} is pressed. You can use [circuit 2] in which the alarm is connected externally.


If you’re connecting external alarm don’t exceed current limit printed on relay.
Materials required:
• LDR [Light Dependent Resistor]
• 2 * 5volt relays
• A momentary push button.
• A buzzer [ only for circuit no.1]
• 4 X spdt switch [ you can use many switch to make you password complicated and unique]
• An old cell phone charger [ But in working condition ]
• 220 Ω resistor[ 220 ohms ]




Please enter your comment!
Please enter your name here