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Looking for latch circuit advice

Discussion in 'Electronic Design' started by Jon Yaeger, Dec 31, 2004.

  1. Jon Yaeger

    Jon Yaeger Guest

    I've got an ATX power supply that I'd like to turn on and off using a
    momentary contact switch. I won't be using it with a computer that has a
    flip-flop type latch circuit - I'll have to breadboard a simple circuit that
    will do the trick.

    There is a 5V DC signal available as a trickle supply. The power supply also
    has a signal lead with 5V which turns on the unit when grounded. It doesn't
    latch on.

    To summarize, I want a circuit to latch the power supply on (using its own
    5V signal & circuit) when the momentary SPST switch is depressed; and off
    when it is pressed again.

    Does anyone know of a suitable on-line circuit?

    TIA,

    Jon
     
  2. Tim Wescott

    Tim Wescott Guest

    You should be able to do this with a toggle flip-flop and a debounce
    circuit. At most this would take a 555 timer and a 7476 -- or save
    space and do it with a PIC.
     
  3. CFoley1064

    CFoley1064 Guest

    Subject: Looking for latch circuit advice
    Hi, Jon. Make it easy on yourself, and use a small push-on/push-off switch,
    like Radio Shack p/n 275-617 for $2.29 USD. KISS principle (Keep It Safe &
    Simple).

    However, if you insist, get yourself a CMOS inverter IC and do something like
    this (view in fixed font or M$ Notepad):
    ___
    .------|___|------.
    | 10K |
    | |\ |\ |
    o--| >O--o---| >O-'
    | |/ | |/
    | .-.
    | | |220K
    | | |
    | T '-'
    | --- | ||
    '--o o---o-----||--.
    || |
    .1uF |
    ===
    GND
    created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

    This should do the job.

    Questions of this type usually get a better reception on
    sci.electronics.basics.

    Good luck
    Chris
     
  4. Jon Yaeger

    Jon Yaeger Guest

    I appreciate your advice - thank you!

    Jon
     
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