In this Instructable I show you how to make a simple door alarm. This alarm is cheap, quick to make, and works well. It was a fun project to do and can be completed within an hour. Have fun with the Instructable!

Video tutorial:

Parts you will need:

Clothespin
2 AA batteries
Buzzer
2 small screws
4 pieces of electrical wire
Piece of plastic (or other non-conductive material)

Step 1: Making the Switch

Drill a hole through the 2 ends of the clothespin. The hole should be slightly smaller than the screw so that the screw can still clamp. Tighten the 2 screws in the clothespin. They must protrude slightly at the rear, the electrical wiring will be attached to this later.

The screws will function as the switch.

Step 2: Installing the Batteries and Buzzer

Put a little hot glue on the clothespin and stick a battery on it. Turn the clothespin over, put some more hot glue on it and stick on the other battery.

Note that one battery has the positive pole on the left and the other battery has the positive pole on the right.

Now put a little hot glue on the side of the clothespin and stick the buzzer on it. The wires exiting the buzzer must be able to reach the battery and screw.

Step 3: Connecting the Batteries

Apply a little solder flux to the poles of the batteries. Now put a little solder on it with the soldering iron.

Solder the + connection of the buzzer to the + connection of the battery.

Connect the - terminal of this battery to the + terminal of the other battery.

Solder a piece of black wire to the remaining - terminal.

Note: A simple wiring diagram has been added to keep it clear.

Step 4: Connecting the Switch

Wrap the 2 wires (- from the battery and - from the buzzer) around the screws in the clothespin. Put a little soldering flux on it and solder the connections.

The buzzer will now buzz! To prevent this, you can put the piece of plastic between the screws.

Step 5: Prepare the Plastic Piece.

Make a hole through the piece of plastic. This can be done with a drill. Because I didn't have the right drill, I did this with the soldering iron.

Put a piece of wire (electrical wire or a piece of string) through the hole and knot it.

Step 6: Ready!

The door alarm is ready! I mounted it against a door with a little hot glue. This can of course also be done with a screw or double-sided tape, depending on the situation.

The string is attached to the frame. When the door is opened, the plastic piece is pulled out of the clothespin and the alarm goes off.

Video Tutorial:

I hope you enjoyed this Instructable and am curious about your reactions and additions!

See you soon,

New Pew