How to Make a Fire Alarm & Heat Detector

Fire alarms and heat detectors differ from smoke detectors, which pick up carcinogens in the air. While not as sensitive as smoke detectors, fire alarms are much easier to construct, and less prone to false alarms from cigarette smoke or cooking mishaps.

1 piece of sturdy plywood 1.5 volt alarm or buzzer 1.5 volt battery 4 pieces of insulated wire Spring-loaded wooden clothespin Electrician's tape or glue Paraffin wax Knife Rubber band

Instructions

- 1
  Strip the insulation off of the ends of the wires so that the metal is exposed. Connect two wires to the alarm's positive (+) and negative (--) terminals and the other two to the battery's positive (+) and negative (--) terminals.
- 2
  Secure both the alarm and the battery to the plywood using glue or electrician's tape. They should be spaced apart, but still close enough for the ends of the wires to touch.
- 3
  Wrap the end of the wire connected to the positive terminal of the alarm to one of the jaws of the clothespin. Do the same thing with the wire connected to the positive terminal of the battery to the other jaw. When the clothespin closes, it should cause the two wires to touch each other.
- 4
  Cut a piece of paraffin wax big enough to fit between the jaws of the clothespin. Wedge it in place so that it doesn't move, securing it with a rubber band if necessary.
- 5
  Attach the clip to the plywood using glue or electrician's tape.
- 6
  Connect the ends of the two remaining wires to each other. At this point, the only thing preventing the connection is the wax. When the temperature gets high enough to melt it (about 120 to 160 degrees F), the jaws of the clothespin will close and the circuit will be completed, starting the alarm.

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