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seeking voltage monitor

Discussion in 'Electronic Components' started by David Lesher, Oct 22, 2007.

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  1. David Lesher

    David Lesher Guest

    I need a few things someone here might know where to find...

    First is a line monitor relay like


    to monitor the AC line. Could be 120 or 240V, even 24V if need be.

    And since none of them I've found have a suitable delay; a
    Delay-on-Operate relay of 2-5 minutes. Not Glass Amperite [too slow to
    reset] but likely octal plugin in. Could be 24VAC or 5/12DC....

    Suggestions -- surplus or new -- welcome...
  2. Jamie

    Jamie Guest

    If you want to spend money!
  3. LVMarc

    LVMarc Guest


    Have built many delay on make delay on make and delay on off and could
    to "custom" relay to match load. By separating the delay timing circuit
    and the relay, each can be optimized inidivdually. Let me know if you
    want me to manufacture some for you!

    Marc Popek
  4. David Lesher

    David Lesher Guest

    Thanks but the delay is the easy part. Many sources for same; would
    prefer non-new pricing.

    Based on futile Googling, ebay and such; looks like voltage monitor will
    be new as well.
  5. ehsjr

    ehsjr Guest

    You may be able to build what you want safely and easily.

    Use a transformer to drop the voltage to 12, single diode
    rectify, filter and use a comparator to detect high or low.
    The same 12V secondary voltage can be used as input to the
    regulated power supply to run the circuit. Use a separate
    rectifier. Conceptually:
    ----- | | + |
    |XFORM|----------+ [C2] [POT]---> to comparator
    AC=| 12V | | | |
    | |---Gnd | Gnd Gnd
    ----- [D1]
    +-----[VReg]---+--- Vcc
    | + |
    [C1] [R1]
    | |
    Gnd +---> Vref To comparator

    The voltage at C2 will vary as the AC mains varies
    and the comparator will respond. You can configure
    a window comparator to provide a "power good" output
    when the voltage is higher than some minimum and lower
    than some maximum. The output can be fed to a relay
    driver or a delay circuit and then a relay.

    It will be cheaper than anything you can buy new to
    do the job.

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