Question about delay timer with LM339 comparator?

Discussion in 'General Electronics Chat' started by samy555, Nov 22, 2013.

  1. samy555

    Thread Starter Active Member

    May 24, 2010
    116
    3
    Hi
    [​IMG]
    Is it C4, C5 or both which control the time delay to ON the transistor?

    Why R4 (3.9M)?
    thank you very much
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,087
    3,027
    C5 controls the turn-on delay once the comparator switches to high. R4 is for a small amount if hysteresis to reduce of chatter in switching the comparator.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    What a horribly complicated circuit.

    You just want to light a LED x seconds after V2 is switched on?

    Or y seconds after V1 is switched on?

    Oh, and this is a death trap. Note that it is referenced to AC line ground, and it doesn't meet the terms of service here...
     
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