IR Receiver triggering on power-up

Discussion in 'The Projects Forum' started by NZMikeV, Sep 13, 2010.

  1. NZMikeV

    Thread Starter New Member

    Jun 18, 2010
    22
    0
    Hello.
    My circuit is driving me 'round the bend, but it's probably a simple solution.
    I am using a 3-pin IR Receiver to detect IR signals from my TV remote control. At this stage I am only interested in detecting a signal. I will be using it as an IR controlled on/off switch in conjunction with a flip-flop. The problem I am having is that, the circuit works fine, except that the IR Receiver sends a pulse when powering up the circuit. This is no good as I don't want any triggering until I send a signal with the remote. I have ommited the flip-flop from the schematic as the mis-behaviour of the IR persists in the simplified version shown here. The monostable 555 is being used as a quick and easy de-bounce and the 1N4004 is to drop the voltage as the IR Receiver(and flip-flop) requires 5V (IR Receiver gives TTL out). I would love to know how to supress or avoid that power-up pulse. I'm sure it's easy, I just dunno how :D
    Cheers
    Mike.

    Datasheet: http://www.jaycar.co.nz/products_uploaded/ZD-1952.pdf
     
  2. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    You can achieve that by holding the 555 in "reset" for a short time after power ON. It can be done via a RC circuit at the 555 reset input pin#4.

    [​IMG]
     
    Last edited: Sep 13, 2010
    NZMikeV likes this.
  3. NZMikeV

    Thread Starter New Member

    Jun 18, 2010
    22
    0
    Thanks for that. I knew it was probably something simple with a capacitor but just didn't have enough knowledge to nut it out.
    Much appreciated. :)
     
  4. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    But does this modification solves your problem?
     
  5. NZMikeV

    Thread Starter New Member

    Jun 18, 2010
    22
    0
    Yes, it works a treat. Thank you.
     
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