This is my first Instructable. This is a very simple and very successful alarm that is actually quite small. The circuit is already made for you and all you have o do is modify it with a switch. When the door opens, it pushes the switch over and it completes the circuit making noise and alerting you of an intruder.
Step 1: Parts and Initial Steps.
1)Birthday/Christmas card circuit
4)Farly large spring
5)Flat head Screwdriver bit
Bend the connector from the battery to 90 degrees
Step 2: Connecting the Wires
Connect one wire to the battery connector and one to the plate. the one from the battery connector goes to the spring and the one from the plate goes to the magnet.
Step 3: Contain the Spring
Contain the spring if you feel necessary. I did and it works better than if it was just hangin all over the place.
Step 4: Screwdriver Bit
The flathead works best because it is kind of flat on the tip and it stands up and falls easily.
Step 5: Finished!
And it is finished. Here it is all together.
Step 6: Where to Put It...
It fits very nicely under a door.