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Apply voltage for X seconds

Discussion in 'Electronic Basics' started by [email protected], Apr 24, 2007.

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  1. Guest

    Does anyone know of a quick way to make a circuit closed for a certain
    period of time after it receives a signal? It's been too long since
    I've messed with most circuit components and I can't remember enough
    specifics.
     
  2. Minimum and maximum time range?
     
  3. John Fields

    John Fields Guest

    ---
    More than likely, a monostable multivibrator (AKA one-shot)

    http://datasheets.maxim-ic.com/en/ds/ICM7555-ICM7556.pdf

    What do you mean by "closed", how long a time, how much current will
    the circuit need, and what will the signal to start the timer look
    like?
     
  4. You need to furthre explain what you mean by "certain period of time",
    seconds/minutes/hours/days? What do you want to happen if the "trigger"
    event occurs again during the timing cycle? Should it be ignored or should
    it restart the timing cycle? Perhaps a NE555 timer, 74hc123, 74hc221 or a
    PIC depending.
     
  5. Jamie

    Jamie Guest

    You need a One shot timer..
    Look on the net for 555 timer examples.
    I assume you need it to only close once and
    release to not close again until you remove the
    signal and recycle it?
     
  6. Guest

  7. Walt Fles

    Walt Fles Guest

    maybe feed the multivibrator into something like a 4106 bilateral
    switch?
     
  8. John Fields

    John Fields Guest

     
  9. JeffM

    JeffM Guest

  10. Walt Fles

    Walt Fles Guest

    Then the bilateral switch can complete a circuit and apply how much
    voltage you need to.
    Depending on what type of circuit needs the voltage and/or how much
    voltage you may end
    up using a diac or triac or scr.
     

  11. Have you ever actually USED a bilateral switch? They are low leve,
    high impedance devices. They are not intnded to switch any current. The
    on resistance is high, and the part number was 4016, not 4106. Also,
    the 4016, and its sucessor, the 4066 are QUAD BILATERAL SWITCHES. Early
    CMOS devices lock up if the voltage is outside the secified range, or
    just quit working


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  12. Walt Fles

    Walt Fles Guest

    Ive used them with op amps as a semiconductor replacement for an atari
    joystick that worked quite well,
    with a potentiometer joysticks hooked to them. That was when Radio
    Shack sold such stuff.
     

  13. That is a completely different application. You were working with
    low signal levels, and high impedance circuits.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
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