In Car PC Power on Power off Circuit

Discussion in 'The Projects Forum' started by 3NRG, Sep 3, 2014.

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  1. 3NRG

    Thread Starter New Member

    Sep 3, 2014
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    Hey Guys;
    I am getting ready to put a Windows based PC in my car (a carputer) and I’m bashing my head against a wall trying to come up with a simple way of powering it on/off with the ignition key.

    I’ve set the PC up so that it hibernates when the Power Button is pressed (it only takes 6 seconds to fully hibernate and 4 seconds to re-start Windows, not bad for a DDR2 667 with a 1.66 socket 479).

    Powering on the PC with the ignition key is a simple enough affair by using a 555 timer configured as a “1 Second - One-Shot Monostable Oscillator” with the trigger closed and the output connected to a relay which in turn is connected to the PC power button.

    Powering off the PC is where I’m having problems, I could use a normally closed relay connected to the accessories and use it to trigger another one-shot monostable when the key is turned off but this seems like a really convoluted way of building a circuit.

    Does anybody have any ideas as to how I might build this into a single package? I’d be happy to pay for a schematic with the component values already calculated, I really need to get this project installed.

    Thanks Guys,

    Regards;
    Mark W.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,056
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    Do you trigger the same button for turn off as well as turn on? If so you just need a single one-shot.
     
  3. 3NRG

    Thread Starter New Member

    Sep 3, 2014
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    Yes same button for both on and off, but the one-shot will only fire with power going to it, and once I turn off the key I lose that power,
    Unless I were to use an NC relay connected to constant power and held open with accessory power and when I turn off the key it would then juice the one-shot,
    that's kind of messy.
     
  4. Georacer

    Moderator

    Nov 25, 2009
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