Pulsed Output from Latched Input

Discussion in 'The Projects Forum' started by Georacer, Sep 22, 2010.

  1. Georacer

    Thread Starter Moderator

    Nov 25, 2009
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    Another problem inspired from the same four-wheeled wreck.

    I want to receive a standard time-length pulse wave of 12 volts (less is good too) when I input a voltage level. That means, when I raise the input from 0 to 1, I expect at the exit one, and only one, pulse of standard duration.

    I thought of a 555 monostable but the output doesn't fall unless the input falls to zero.

    I want the project as small as possible.

    Thanks in advance!
     
    Last edited: Sep 22, 2010
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    The attached circuit will trigger on the leading edge of the input signal, and will time out even if the input remains high. Does this fit your needs?

    Ken
     
  3. Georacer

    Thread Starter Moderator

    Nov 25, 2009
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    Actually, I have only 0.5 Volt, not enough to turn on the transistor, but I can work around that.

    Thanks a bunch!
     
  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Ahhh! Details...details...details. ;)

    Ken
     
  5. tom66

    Senior Member

    May 9, 2009
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    You could use the biasing method I talked about on the last thread. (Remember the resistors should probably go up to Vcc and down to ground, not to collector and emitter.) A comparator could also work.
     
  6. Georacer

    Thread Starter Moderator

    Nov 25, 2009
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    Yeah, the comparator is what I had in mind.
     
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