Connect with us

Help with single pulse circuit

Discussion in 'Electronic Basics' started by The Jackal, Sep 29, 2003.

Scroll to continue with content
  1. The Jackal

    The Jackal Guest

    I'm sort of a beginner when it comes to electronics. What I need is a
    circuit that will receive +VCC for a fixed amount of time (say a
    minute) but only give out one single pulse until the circuit is reset.
    I need this to run one of those house bells that run on batteries,
    where you only need to press it once. Connecting it directly to the
    circuit wouldn't do, since it would keep on ringing as long as the
    +VCC is on, whereas I only want one ring.

    Thanks.
     
  2. Wouldn't it be be best way to use the button to directly turn on and off the
    voltage source? I don't know if there is a reason for wanting a separate
    circuit so post a reply if if missed something.

    Andrew Howard
     
  3. Sounds like you need something like a one-shot or similar. Perhaps
    something like the 74HC4538 might be what you are looking for.

    http://www.fairchildsemi.com/ds/MM/MM74HC4538.pdf
     
  4. Are you implying that a 4528/4538 can't be configured as
    non-retriggerable? Check the data sheet. It can be wired for + edge, -
    edge triggering and either retriggerable or non-retriggerable. Also,
    the time constants for 4538 are the simplest there are. See page 9 of
    the ON semi PDF.
    http://www.onsemi.com/pub/Collateral/MC14538B-D.PDF

    I just looked through the Fairchild data sheet. No wonder you're
    confused. I always liked the Motorola (now ON semiconductor) data
    books when I played with CMOS 20+ years ago. I'm sure glad I didn't
    see the Fairchild (type) books first.
    gg
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-