How to make your own intruder alarm.
1 x 9V Battery
1 x 9V Battery snap connector
1 x 9V Buzzer
1 x Clothes peg
1 x Sheet of tin foil
1 x Piece of string
2 x Lengths of wire
1 x Playing card
Tools and equipment
- Strip the ends of the snap connector, the buzzer, and the two lengths of wire, with a pair of nail clippers.
- Tear off two strips of tin foil and wrap them around the prongs of a sprung clothes peg.
- Tape one end of each length of wire to the tin foil patches on the clothes peg.
- Twist the end of the red wire on the buzzer to the end of one clothes peg wire.
- Twist the end of the red wire on the snap connector to the end of the other clothes peg wire.
- Twist the ends of the black wires on the buzzer and the snap connector together.
- Tape a piece of string to the playing card.
- Clip the playing card in the clothes peg.
- Tape the clothes peg to the wall beside your door.
- Tape the end of the string to your door.
- Connect the 9V battery to the snap connector.
- When an intruder opens your door the card will be pulled out of the peg and the buzzer will sound.
Perhaps you could add a light to the circuit too?