Making a burglar alarm for a bedroom door with a buzzer

Make homemade theft alarm for a bedroom does not have to be difficult. All that is required is a small buzzer, a power supply, and a closed circuit. The key to operate the door alarm is on closing the circuit when someone tries to enter the room.

The metal conducts electricity so it is an optimal choice for use as an electrical bridge. When the metal is not in contact, breaks the circuit and stops emitting alarm sound. When the metal is touched, the circuit is closed and shoots a device that emits sound.

You will need: Buzzer, 9V battery, Strippers, Welder.


  1. Peel the two exposed wires in one inch (2.54 cm) on the head battery 9V. Also strips the two speaker wires to one inch (2.54 cm). The threaded copper wire should be visible.
  2. Solder the black wire from the battery 9V to one of the speaker wires. The black wire is Ground and prevents the circuit from burning.
  3. Welding a piece of sheet metal to the red wire from the battery 9V. Do the same for the free wire buzzer.
  4. Paste the buzzer and battery 9V at the door of the room, near the bottom of the door.
  5. Paste one of the connected pieces of sheet under the door off the hinges.
  6. Paste the remaining piece of sheet metal in the soil an inch away from the sheet metal piece attached to the bottom of the door. Do this so close to the side hinge as possible so the two pieces of metal are in contact and complete the circuit during the time the door is open.