How to Make a Small Alarm
High-tech burglar alarms can be extremely intimidating, but most of them operate based on a very simple principle. All you need to make a burglar alarm is a loud noise such as a buzzer and a means to reliably trigger it. If you have that, then you can make a small alarm yourself using nothing but a few household items and some common supplies from an electronics store. It can be easily mounted to any door or window, providing excellent security for just a few dollars. Does this Spark an idea?
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Things You'll Need
- Spring-operated wooden clothes pin
- 3 lengths of insulated electrical wire (6 to 12 inches)
- 1.5-volt battery
- 1.5-volt buzzer
- Electrical tape
- Thin piece of cardboard
- String
- Pushpin
- Flat wooden board large enough to hold all components
Instructions
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1
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.
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2
Place a thin piece of cardboard between the jaws of the clothespin to keep the wires apart.
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3
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.
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4
Secure the battery, buzzer and clip to a thin piece of wood using glue or electrical tape.
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5
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.
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6
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.
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7
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.
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Tips & Warnings
Because this alarm is so small and simple, it can't do anything beyond making a loud noise. It's up to you to call the police when you hear it. In addition, you may wish to inform your neighbors of the alarm's sound, so they can call for help if it goes off when you're not home.
