Stop Thief

A “Stop Thief” electronic project is a circuit that can detect unauthorized entry into a room or a house and sound an alarm to alert the homeowner.

The burglar alarm circuit works by sensing the change in light level that occurs when someone opens the car door. The CDR acts as a light sensor and is placed near the door where it will be exposed to light when the door is opened. When the light level decreases, the resistance of the CDR increases, causing the voltage at the base of the NPN transistor to decrease. This turns the transistor off, allowing current to flow through the speaker and generate a loud sound, indicating that someone has opened the car door.

Note: This is just a basic burglar alarm circuit for a car, and it is recommended that you add more features, such as a delay or a hidden switch to disarm the alarm, to make it more effective. Also, keep in mind that car theft is a serious crime, and it is always recommended to take additional measures to secure your car, such as using a steering wheel lock or parking in well-lit areas.