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Homework Help: Creating a small alarm using a capacitor, resistors etc

  1. Nov 24, 2012 #1
    1. The goal is to create a small alarm that goes off for exactly 6 seconds before turning off. The materials allowed are 1000 1 ohm resistors, wire, a box of rechargeable 1.5 V triple A batteries (12 count) and a piezoelectric buzzer.

    2. Ohms Law. Power = V2/R

    3. I have a design without the capacitor that is consistent of a piezoelectric buzzer, 200 1 ohm resistors, and 12 batteries so that the time for which my alarm sounds is around 3 days and 3 hours.

    I'm not sure how to make it so that it sounds for exactly 6 seconds with a capacitor...
  2. jcsd
  3. Nov 24, 2012 #2


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    Please share what you have done. What triggers the alarm?
  4. Nov 24, 2012 #3
    Basically it is a small alarm that one would put around a room that has only a window. When someone opens this window, the alarm starts going off. My design prior to the capacitor was of a piezoelectric buzzer (400 ohms) in parallel with a 100 ohm wire, which was in turn in series with a 200 1 ohm resistors connected to two 9 volt batteries in parallel.
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