security door alarm circuit diagram

Hello, today I will show you how to make a security door alarm, the door alarm is easy to make and give the best result.

The door security alarm provides a very long battery life and easy installation, the circuit use only 2.4 volts to operate so you can power the circuit with 2xAA rechargeable battery or even you can use a lithium-ion battery with auto charging circuit as power supply because the circuit can withstand up to 5 volts power supply. 

If you want to change the power supply to 12 volts, you simply need 7805 IC to regulate 12 volts to 5 volts without any problem. You also can use 12 volts Buzzer instead 5 volts Buzzer that I used in the circuit and connect directly to 12 volts power supply (solar charger's output, 12 volts car battery).

The SCR (thyristor) in this circuit can withstand current up to 3 A so you can connect 20 Buzzers (estimate 100 milliamp/hour per Buzzer) with one circuit module without making any damage to The SCR. You also can change the SCR model if you want smaller circuit.

Component list

5 volts Buzzer

1 kilo-ohms resistor

3 leg limit switch

SCR 3p6mh (You can use another SCR model without any problem just check K, A, G pin is correctly used)

Door security alarm circuit diagram

Door security alarm working and circuit explain 

Feel free to ask any question about my project in comment box below