This is my fourth instructable. It is on how you can make an alarm without any expensive equipment. It takes very short to set up too.
battery with holder
Step 1: Step one: battery
attach the battery/holder to the wall with tape (see pic) attach wires flowing downwards.
Step 2: Step two: attaching the reed switch
attach the reed switch to the hanging wire from the battery close but not touching the door
Step 3: Step three: bar magnet trigger
when a reed switch comes close to a magnet both parts attract causing them to come together and continue the flow of electricity. Attach the magnet with tape to the inner part of the door so it can swing.
Step 4: Step four: attaching the buzzer
add a wire flowing from the other side of the reed switch. This should then go to the buzzer. The attach an other wire flowing up (see red wire)
Step 5: Finishing touchings
attach the final two wires so that the circuit is complete now when the bar magnet comes close to the reed switch it will buzz. To make a disarmer put a piece of tape under the magnet and reed switch (see pic). Now you can put a piece of thick paper between the magnet and reed switch from the outside and be able to walk in without it going of. You may have to adjust it to your desire. Thanks for viewing my instructable!