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Thread: Turn Constant 12V to a momentary push w/ voltage change

  1. #1
    Maximum Bitrate KyleYankan's Avatar
    Join Date
    Mar 2005

    Turn Constant 12V to a momentary push w/ voltage change

    Hi everyone. I'm trying to make my own "startup/shutdown controller" and I have a small problem.

    I plan on using 2 relays. One relay will be connected to the 12v ignition - on when the car is on. This enables power to the inverter. This automatically turns my pc on (turns on as soon as pwoer is applied - bios settings). Now, I plan to run the 2 relays in parrallel, so if either relay is on, the inverter is still getting power. Like I said 1 relay turns on with the ignition. the other realy will be wired to the pin1 of LPT1, and will be wired to turn off power once there is no signal from pin1 (pc is off). This should work to feed power to the PC even after the car is turned off, so it can shut down automatically. However there's one vital flaw: Making the computer know when to start the shutdown routine. It's a big ugly desktop, so Igot no problems soldering the switch up. However, I imagined having some kind of circuit hooked up to the ignition relay, that would "pulse" the power button, as soon as the relay loses power. Easy to do: Hook it up to the NC contacts, so the circuit is engaged. Then the circuit holds down the power button for 1-4 seconds.

    So, in summary is there a cheap circuit that when power is applied, can activate a relay to cycle a power button for 1-4 seconds?

    Thanks in advance for any help. I've tried searching, but all I get is people complianging about soldering there laptops power button.

  2. #2
    What can I say? I like serial. Curiosity's Avatar
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    Mar 2004
    Florence Yall, BFKY
    search for "fake ups"
    should do what you want

  3. #3
    Join Date
    Sep 2003

    that should do what you need... it's the "constant to momentary" one

  4. #4
    Maximum Bitrate KyleYankan's Avatar
    Join Date
    Mar 2005
    Thanks danielsmith, that's exactly what I needed. I just need to look in the fuse panel and see wherei can hook the 12v ignition wire up to.

  5. #5
    MySQL Error Scouse Monkey's Avatar
    Join Date
    Mar 2004
    for a thread about laptop startup/shutdown controllers there are some circuits there.

    Also try searching fo 'pulse' and 'relay'.

    Sorry i cant be anymore help but am using my laptop through my phone so searching is out fo the question as its a bit slow.

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