LDR Sensor based Laser Security System

If you want to make your surroundings safer then it comes to security. What if you can protect your house or garage or any important belongings with the help of a laser system. Whenever the laser got interrupted, it will sound an alarm to make you alert that someone has invaded.

So, In this tutorial, we are going to learn how to make a laser security system just with the help of a transistor and a few basic components. Let’s make it!

Laser Security System Circuit Diagram

In the above circuit diagram, we can see that the NPN transistor is acting as a switch whose base is connected to the 10Kresistor and one terminal of LDR. A 9volt power supply is given to the collector of the transistor. The buzzer is connected to the emitter terminal of the transistor. The emitter terminal and another terminal of LDR are connected to the ground with the help of an ON-OFF switch.

The laser setup has a simple 3voltcoincell to power the laser and an ON-OFF switch is connected to it.

Laser Security System Working

The working of the circuit is simply based on a voltage divider circuit. As the light intensity on LDR increases its resistance decreases, so when laser light is falling on LDR, its resistance goes very low hence the 9volt supply gets connected to the ground with the help of a 10K resistor, and in this way base of the transistor receives low value or in other words transistor is OFF.

Now as soon as light intensity decreases or it laser gets interrupted by someone, LDR resistance increases which in turn gives a high value to the base of the transistor, and hence transistor turns on, and finally, the buzzer sounds up. In this way, our project is working and providing us with a security system using a laser.

The final Project looks like this.