Constant to Momentary Relay PC Applications

Discussion in 'The Projects Forum' started by BWHH, Jul 22, 2008.

  1. BWHH

    BWHH Thread Starter New Member

    Joined:
    Jul 22, 2008
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    Hi All,

    I'm looking to build a simple circuit that would take a contstant 12v feed and momentarily trip a relay.

    The plan is to use this:
    http://www.newegg.com/Product/Product.aspx?Item=N82E16811994010

    To turn a PC on and off, but the trigger on the PC only needs the power switch to be closed momentarily.

    Any ideas?

    Thanks for the help!
  2. SgtWookie

    SgtWookie Expert

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    Location:
    In the vast midwest of the USA; CST
    If a PC is plugged in, there is a 5V source that's always available.

    Check out the specifications for the power supply in your PC by form factor.

    There is really no need for an external supply.

    But perhaps there is. You need to give more details.
  3. BWHH

    BWHH Thread Starter New Member

    Joined:
    Jul 22, 2008
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    What I want to do is power up a PC using the remote control. The problem is, a power switch on a PC is momentary.

    This would be independent of the system's PSU. All I'm really trying to do is replace the simple momentary power switch on the PC with a remote control. With the remote I've linked, I would need a way to take its 12v output to trip a relay, but the relay would need to disengage in a second or two max.
  4. rezmax

    rezmax New Member

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  5. p_circuit

    p_circuit New Member

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    Aug 4, 2009
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    The diagram shows that the capacitor is installed between the ignition switch a nd the ground> Is this correct?

    Is that a standard automotive relay?> I though you need a 2 way coild relay for the momentary function to work.

    Does the value of the resistor matter in relation to the cap?

    Is the resistor installed on the ground end of the relay?

    Does the resistor bring the capacitor back to 0v after the ignition source is switched off?
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