How to Make a Small Alarm

Strip the insulation off the end of a piece of electrical wire (leaving about 2 inches bare) and wrap the bare wire around the top jaw of a spring-operated wooden clothespin several times. (The wire should be about 6 to 12 inches long in total.) Repeat the process with a second length of wire, this time wrapping it around the bottom jaw of the clothespin. When you're finished, the two wires should come into contact when the clothespin is closed, and be apart when the clothespin is open.

Place a thin piece of cardboard between the jaws of the clothespin to keep the wires apart.

Connect the free end of one wire to the negative housing in a 1.5-volt battery. Connect the other to the positive housing in a 1.5-volt buzzer. Then use a third wire to connect the positive terminal on the battery to the negative terminal on the buzzer. You now have a completed circuit; when the cardboard is pulled away from the clothespin, the alarm will go off.

Secure the battery, buzzer and clip to a thin piece of wood using glue or electrical tape.

Use a pushpin to make a hole in the piece of cardboard and run a length of string through it. Secure the loose end of the string to the door or window you wish to protect.

Secure the piece of wood containing your alarm components to a nearby wall or table. It should be firmly in place so that it doesn't move when the door is opened.

Wait for a burglar. When the door or window is opened, it will pull the cardboard out of the jaws of the clothespin, setting off the alarm.