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Need help with electric circuit

  1. Jan 21, 2010 #1
    I have a circuit in which I have a constant voltage passing through until I hold down on a button at which point the voltage drops to zero. When I let go of the button the voltage returns to normal. I need to add to the circuit a switch which activates when a voltage of zero is passing through and remains turned on until a voltage of zero is again passing through.
    How Can I do this?
  2. jcsd
  3. Jan 22, 2010 #2


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    Google Normally Closed Switch.

    Multi pole relays have both normally open and normally closed contacts. Look for NO and NC on the case switch diagram.
  4. Jan 22, 2010 #3
    Voltage cannot pass through components in a circuit. Voltage is a quantity measured across terminals in a circuit. Only current can pass through components in a circuit. Any way from your question I guess you may have to use a negative edge triggered Toggle Flip Flop. The output of toggle flipflop should be connected to a relay.
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