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How to Make a Burglar Alarm for a Bedroom Door With a Buzzer

Making a homemade burglar alarm for a bedroom does not have to be difficult. All that is required is a small buzzer, a power source, and a closed circuit. The key to making the door alarm work is closing the circuit when somebody tried to get into the room. Metal conducts electricity so it is an optimal choice for being an electrical bridge. When the metal is not touching, it breaks the circuit and the alarm ceases to emit sound. When the metal touches, it closes the circuit and fires off a device that emits sound.

Things You'll Need

Buzzer
9V battery
Wire strippers
Soldering iron
Solder
2 1x1 inch sheet metal
Super glue

Instructions

- 1
  Strip the exposed two wires by one inch on the 9V battery head. Strip the two wires on the buzzer one inch as well. Copper threaded wire should be visible.
- 2
  Solder the black wire of the 9V battery to one of the wires of the buzzer. The black wire is ground and will prevent the circuit from burning out.
- 3
  Solder one piece of sheet metal to the red wire on the 9V battery. Do the same for the buzzer's free wire.
- 4
  Glue the buzzer and the 9V battery to the bedroom door near the bottom of the door.
- 5
  Glue one of the connected pieces of sheet metal under the door on the side with the hinges.
- 6
  Glue the remaining piece of sheet metal on the floor one centimeter away from the piece of sheet metal glued to the bottom of the door. Do this as close to the hinge side as possible so the two pieces of metal remain in contact and complete the circuit for as long as the door is open.

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