- 1). Wrap one 1-foot piece of non-insulated wire around the positive end and another around the negative end of a 1.5-volt battery. This is the beginning of the circuit that will run between the alarm and the activator. Apply electrical tape to hold the wires in place on the battery. Don't let the wires touch after you attach them to the battery or you may shock yourself.
- 2). Squeeze the handles of a clothespin to open it. Wrap a 1-foot piece of non-insulated wire around each tip of the opening so that when you release the handles to close the pin, two independently wrapped ends contact each other. This is the activator for the alarm.
- 3). Cut a small piece of cardboard, 1-inch square. Tie the end of a 5-foot piece of string securely around the middle of the square and insert the square between the wrapped ends of the clothespin. This will keep the alarm from going off when you connect the switch to the battery.
- 4). Twist the end of one of the wires connected to the battery around one of the wires attached to a 1.5-volt buzzer. Wrap the end of the other wire connected to the battery around one of the wrapped ends of the clothespin.
- 5). Wrap the end of a 1-foot piece of non-insulated wire around the second wrapped end of the clothespin. Twist the other end of the wire around the second wire attached to the buzzer. This completes the circuit that makes the alarm work.
- 6). Remove the cardboard square from the switch to see whether the buzzer works. If you hear no sound, twist all the wires in the circuit together to make them more secure until the buzzer sounds. Replace the square when the alarm works.
- 7). Tape the battery and buzzer flat to a piece of plywood with electrical tape to secure them in place. Use a strong glue on one of the non-wrapped ends of the clothespin to secure it to the plywood.
- 8). Tie the string connected to the square securely to the knob of the door you want to secure. Set the circuit board nearby so that you are able to close the door without tripping the alarm but so that turning the knob to open the door will cause the square to come out of the clothespin and set off the alarm. It may take trial and error to find the right position.
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