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Thread: Powerswitch

  1. #1
    Newbie
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    May 2001
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    Post Powerswitch

    I think I posted this is the wrong discussion, so I've posted it here
    Greetings! THis is my first post so please forgive my ignorance. I am building a simple mp3 player for my car using a pII300mhz processor, and a palm interface. Later on I want to add more features. I've got everything working on the bench, except i have no clue howto control the power on, power off of the computer, that is, my computer doesn't turn on automatically when power is applied to it, it requires you to press, then depress a switch. I have found where the power switch (from the computer)leads to on the motherboard. Will someone please help me devise a way of powering on and off. thanx!
    PS. IF there is a way to do this automatically when the ignition is on that would be great, I really am not to worried about proper shutdown....yet ;-)

  2. #2
    Variable Bitrate
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    Apr 2001
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    Post

    You can find the hot/positive and ground leads on the switch on the PC, remove them from the switch and simply connect them together either by soldering or using crimp-on connectors. Make sure you do any work on the PC with the power plug disconnected from the PC. By connecting the hot and ground leads together the PC will turn on when power is applied to the power supply.

    To turn on/off the PC you can either install a 30A SPST(single-pull, single-throw) switch somewhere between the power source and the PC. Remember to install either 25A or 30A fuse on the power connections on both the hot(positive) and ground leads close to the power source. To get the PC to turn on/off with the ignition you can run a 14 or 12 gauge wire from an empty ignition-switched fuse slot in your interior fuse box to a 30A relay like the one Radio Shack sells, Cat.#: 275-226. That relay has four contacts. You connect these connections to its own contact on the relay: the hot power lead coming from ...say your battery, the wire from the ignition-switched fuse slot, a ground wire, the hot lead going to the PC. You would ground the PC to either chassis or the ground/negative on the battery.

    The relay will sense the voltage on the ignition-switched contact when you turn the key and it will then close the circuit to the main hot power lead thereby applying power to your PC. When you turn your key off the relay will sense the loss of voltage on the ignition-switched contact and open the main hot lead going from your battery to the PC.

    I strongly advise to have someone experienced do this work or assist you if you've never done it before.
    P4 2.4GHz, Intel mobo w/onboard sound & video, 128MB memory, 100GB Seagate Momentus laptop drive, Xenarc 700TSV 7" touchscreen, IRman using Girder, 150W Opus dc/dc psu, Alpine CDA-9835 h/u, MBQuart speakers, Infinity 15" sub, MTX amps.

  3. #3
    Variable Bitrate
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    Jul 1999
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    Post

    Actually Tony S he can't just solder the leads from the power switch together. He is describing an ATX machine. So Chipmunk one thing you can do is look in your BIOS settings(depending on the PC there may be a line that says something to the affect of "Press F10 to enter setup" if you need more help on how to get into the BIOS setup just ask) In most ATX BIOSes there should be an option somewhere to change how the computer is turned on. see if you can change it to say "Turn on when power applied" or something similar.

    Catlas

  4. #4
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    May 2001
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    Post

    I have an "Award BIOS", and I was unable to find this option, can you tell me EXACtly what to look for?

    thanx

  5. #5
    Maximum Bitrate gizmomkr's Avatar
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    Smyrna, Ga, USA
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    Post

    Chipmunk-

    In my bios the function is found under the advanced setings, "Resume after power fail" and has the options of "on" or "off"
    Gizmo-
    Techonlogy on Wheels
    http://www.hjnetworks.com/car

  6. #6
    Maximum Bitrate
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    Cincinnati, OH USA
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    Post

    You can use the auto shutdown controller that will properly startup and shutdown the computer when the car is started. Probably the easiest way to go!
    http://www.mp3car.com/usersites/Maveric/ M.A.V.I.C. System
    Asus MB, PII 266, 192 MB Ram, 6.8" LCD, 6 Disk CD-ROM, 21 Gig HD, All-in-Wonder Video w/ TV Tuner, Irman, Windows ME, Winamp, Cobra III -- All in a custom acrylic case.

    http://www.mp3car.com/usersites/listings/ MP3car Listings - Please add to it! :)

  7. #7
    Variable Bitrate
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    Post

    Or you can build a delay circuit that acts the same way. This guy's circuit's pretty easy. Look under the "DIY" section, click on "delay". http://pluto.spaceports.com/~mpdj/
    P4 2.4GHz, Intel mobo w/onboard sound & video, 128MB memory, 100GB Seagate Momentus laptop drive, Xenarc 700TSV 7" touchscreen, IRman using Girder, 150W Opus dc/dc psu, Alpine CDA-9835 h/u, MBQuart speakers, Infinity 15" sub, MTX amps.

  8. #8
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    May 2001
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    Post

    THANX GUYS!
    After reading your posts, and receiving info from some of you through e-mail. I cannibalized connecter that connects the reset button to the motherboard, and attached a long wire to that which goes to an ordinary switch... Do you have any ideas how many amps i need the switch to be?

    thanx

  9. #9
    Variable Bitrate
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    Sorry but I can't help you with the specifics because a)I don't have an award BIOS and b)I don't have an ATX machine. So basically all I'm good for is theory . So anyone here with an ATX machine with an Award BIOS that could help out?

    Catlas

  10. #10
    Variable Bitrate
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    Post

    You could use a 20A or 30A switch, obtainable from Radio Shack.
    P4 2.4GHz, Intel mobo w/onboard sound & video, 128MB memory, 100GB Seagate Momentus laptop drive, Xenarc 700TSV 7" touchscreen, IRman using Girder, 150W Opus dc/dc psu, Alpine CDA-9835 h/u, MBQuart speakers, Infinity 15" sub, MTX amps.

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