This is a good little buzzer alarm if you don't have to secure too many entrances. It requires limited resource and electronic skills. It is designed to use a single switch which is triggered when a door opens, but can be easily modified to include multiple switches and to secure windows as well as doors.
Things You'll Need
- Insulated copper wire
- Soldering iron
- Neodymium magnet
- Iron plate
- Power supply
Get your power supply. The power supply needs to match the buzzer. It should provide as close to the required voltage as possible without going over, and at least the required amperage. For example, if the buzzer requires 8.3 volts, an 8 volt power supply will work, but a 9 volt one could damage the buzzer. If it requires 50 milliamps, however, a 100 milliamp power supply will work fine.
Solder one terminal of the buzzer to one terminal of the power supply. You can either connect them directly or use a length of copper wire between them.
Mount the buzzer and power supply somewhere. Put the buzzer in a small box to protect it and attach it to a wall above a wall socket where you can plug in the power supply.
Cut two wires for the trigger mechanism. They need to be long enough to reach to the door with a few feet of extra give.
Solder one of the wires onto a small rectangular iron plate, at least two inches on each side. Soler the other wire onto a neodymium magnet.
Connect the other ends of the wires. One of them should be attached to the open terminal of the power supply, the other to the open terminal of the buzzer. It doesn't matter which is attached to which.
Tape the plate on to the foot of the door. Place the magnet in front of the door, so that when the door is opened, the magnet will touch the plate. This will complete the circuit, triggering the buzzer.
Tips & Warnings
- To guard multiple doors, simply construct another trigger mechanism and attach it in exactly the same way as the first one is attached. That way, if either door is opened, it will trigger the circuit.
- There are other ways to trigger the circuit. As long as the two loose wires make contact when the door is opened, the alarm will sound.
- Do not plug in the alarm until you have finished wiring the circuit. Unplug it before you deactivate it unless it produces very low amperage.
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