Passive RF "Listener" Circuit

Discussion in 'The Projects Forum' started by trianta2, Aug 6, 2012.

  1. trianta2

    Thread Starter New Member

    Aug 6, 2012
    2
    0
    Hello All,

    I'm trying to do a project that requires an RF transmitter to "wake up" a circuit, possibly miles away. The circuit that is being woken up will be in a deep sleep mode, as its power source is very limited.

    Can anyone point me in the direction of a circuit that does not consume any power, or consumes very little power, but can be "woken up" by an external signal? The functionality I'm looking for is identical to a remote entry car key.

    Thank you for your time and input!
     
  2. trianta2

    Thread Starter New Member

    Aug 6, 2012
    2
    0
    bump! anyone out there?
     
  3. wayneh

    Expert

    Sep 9, 2010
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    Could you only "listen" on the receiver end at a very low duty cycle, say 1 second every 10 minutes? This would require as long as a 10 minute delay with the transmitter on, before the receiver takes a look and sees that it should power up fully.
     
  4. #12

    Expert

    Nov 30, 2010
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    That's the method. The thing that stops me is: a legal transmitter with miles of range.
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,137
    3,054
    Ha ha, great point! Didn't even cross my mind. I guess CB qualifies.
     
    Last edited: Aug 8, 2012
  6. #12

    Expert

    Nov 30, 2010
    16,306
    6,816
    I believe it is possible, but it's outside my field of knowledge.
     
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