Pressure Switch/Burglar Alarm

    Supplies
  1. 2 8.5" Stryrofoam plates (if not available, you can use paper plates or try some cardboard)
  2. tape
  3. 18-24" of speaker wire or 2 18-24" wire
  4. aluminum foil
  5. roughly 3.5" square of bubble wrap (styrofoam wrapping paper, cardboard, or the like)
  6. glue
  7. scissors
  8. wire strippers

    Instructions
    NOTE: conductor and wire are used interchageably in these instructions.
  1. If using speaker wire, separate the two wires for about 4" on each end of the wire. You should be able to do this with your finger nail.
  2. Using wire strippers, strip about 3/4" - 1" of the insulation from each end of the conductors (4 ends).
  3. Using the scissors, poke a hole (big enough to pass your wire through) in each of the plates on the flat part but on the outer part of the circle.
  4. Pass one end of one conductor through the hole in the plate from the back to the front. Pass one end of the other conductor through the hole in the other plate from the front to the back.
  5. Cut some aluminum foil into 2 rectangles about 2"x3" (be sure that no dimension is bigger than your bubble wrap square) and glue them so they cover the stripped ends of the wire plus a bit of the insulation. One will be on the back of a plate and the other will be on the front as in this picture.
  6. Now, fold the bubble wrap (or other material) in half and cut a small semi-circle in the fold so that the unfolded circle will be about 2" in diameter. Do not make the hold too big or have the foil too large as it is in top picture at right.
  7. Bad
    Good
  8. Now, nest the plates with the bubble wrap in the middle between the foil strips as in the picture ar right and tape the plates together as seen in the photo at the top
  9. Your switch is complete, when stepped on or pressed together in some way, the foil will make contact through the hole in the bubble wrap and complete a circuit. This circuit can be used to light a bulb.
  10. Or, to make it more interesting. Place some foil on the stripped ends of the wires and place a small piece of paper between the 2 foil-wrapped wire ends. Then, set these in the battery compartment of your favorite toy or radio -- between the negative (-) end of the battery and its contact is the easiest. Turn the toy or radio on. It should be off until your pressure switch is pressed. Now you have a burglar alarm!
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