A laser-based security system is a type of security alarm that uses a light sensor and laser light. In this tutorial, we are going to demonstrate a circuit of a laser security alarm system that will detect any irregular activity and will produce sound using a buzzer. One of the main components of this circuit is LDR. It will detect dark and light laser beams and will change its resistance to send a signal to the buzzer.
This laser security alarm is economical and you can make it at home without any professional skills required. For properly operating this alarm you have to make sure that no other light reaches LDR other than the laser beam. You can use a box with small holes for this purpose.
Hardware Components
The following components are required to make Laser Security Alarm Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Battery | 9V-12V | 1 |
| 2. | Capacitor | 1000uF | 1 |
| 3. | Transistor | 2N4403 / 2N3906 | 1 |
| 4. | Variable Resistor | 50K | 1 |
| 5. | Piezo Buzzer | – | 1 |
| 6. | LDR | – | 1 |
2N4403 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 2N4403
Laser Security Alarm Circuit
Working Explanation
In this circuit, we are using LDR ( Light Dependent Resistor) which is actually a variable resistor. Normally LDR has high resistance and when light falls on its surface, its resistance decreases this allows the transistor to conduct, and as a result of this change in resistance buzzer will be turned on. We are using a 9V to 12V DC battery for this circuit.n Sensitivity of this circuit will be adjusted by a 50K resistor.
Applications and Uses:
- It can be used in safety lockers of homes and offices.
- It can be used to check if pets and babies cross a certain limit of the boundary.
- It can also be used in jails for keeping criminals within certain boundaries.
