How to Make a Burglar Alarm

You can create a simple, rudimentary burglar alarm largely with things you already have around the house. It is perfect as a science project for children or as a basic outline for a more elaborate plan.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Wood board
• Battery (1.5V)
• 1.5V alarm or buzzer
• Clothes pin
• Electrical wire
• Electrical tape
• Cardboard
• String
• Scissors
• Hole puncher
• Super glue

1. Get a wood board about 8 inches wide by 12 inches long.

2. Tape a 1.5V battery to the board in the upper left corner.

3. Strip a 1-inch long piece of insulation off of each end of the two electrical wires attached to the 1.5V alarm or buzzer.

4. Tape the alarm or buzzer to the board in the upper right corner, making sure one of its wires can reach the battery.

5. Tape one alarm wire to one end of the battery.

6. Wrap the second wire's uninsulated end around one closed end of a clothes pin.

7. Strip a 1-inch long piece of insulation off of each end of a 12-inch length of electrical wire.

8. Tape one end of the wire to the free end of the battery.

9. Wrap the other end of the wire around the closed end of the clothes pin and make sure that the wire touches the wire on the opposite side of the pin from Step 6. When the clothes pin is closed, the circuit is complete and the alarm should sound.

10. Cut out a small square of cardboard a few inches square.

11. Punch a hole in the cardboard square with a hole puncher.

12. Open the clothes pin and put the cardboard square between the ends of the pin directly between the two wires and let it close around the square.

13. Cut a length of string.

14. Tie one end of the string to the cardboard square through the punched hole.

15. Glue the clothes pin to the bottom middle of the wood so that the pin can be opened and closed.

16. 
    Burglar Alarm

    Tie the loose end of the string tightly to a door, window or whatever you want the alarm to protect. When the string is pulled, the cardboard will be pulled out of the pin, the wires will complete the circuit and the alarm will sound.