delayed output timer

Discussion in 'The Projects Forum' started by dburleson, Feb 2, 2012.

  1. dburleson

    Thread Starter New Member

    Feb 2, 2012
    2
    0
    I am looking to build an automatic controller for an audio switcher that will switch automatically upon loss of audio. The receiver provides a closed contact upon audio loss for the trigger. I need a timer circuit that will ignore short losses of less than 3 seconds, but if the loss is longer than 3 seconds it will output a pulse that can be used to make the switcher switch to backup audio.
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,148
    3,058
    Not really sure if it would work, but there is a circuit known as a missing pulse detector. It can be made using the 555 timer IC. Basically, audio peaks continuously reset the timer. When audio stops and fails to reset, the timer goes through its cycle, ultimately changing the output state.
     
    dburleson likes this.
  3. dburleson

    Thread Starter New Member

    Feb 2, 2012
    2
    0
    Thanks, I will look into that, since I have hit brick walls with everything else.
     
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