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Startup controller help.

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  • Startup controller help.

    Alright. Here's the deal. I don't want to invest in an OPUS 150 right now becuase I am leaving for Iraq in two months. After a year, I'm assuming something new will be out and then that's what I will get. So for the time being I am using the inverter and power supply method.

    It works great but I have to manually turn it on (at the moment I am jumping the PWR SW pins on the motherboard), but that requires dropping the back seat to do so. I've already determined that I need to hook my inverter up to my 12VDC ACC (switched) wire to ensure that the inverter does not continue to run when the car is off (mine won't last through the night). Okay so the inverter will turn on when the car turns on.

    Great! But I still can't power on the computer. I can't simply use a relay to connect the PWR SW pins on the motherboard because that will start it up and then shut it off after 4 seconds. I don't have a setting in the BIOS to Resume after Power Failure. It doesn't appear that I have a WOL header on my motherboard. Jumping Pins 4 & 8 on the Com port doesn't seem to work. Sending +5VDC in Pin 9 of the Com port also doesn't see to work.

    After a bunch of ing, I've seen one user make reference to a Cube Timer with a Relay that he uses but can't really find what I need through Google (there's billions of different components). I've sent the user a PM to get more info. I did find this, however, and this seems like it would be the best thing for me at the moment:
    Originally posted by
    The capacitor allows the coil of the relay to be energized until the capacitor stores a charge, thus de-energizing the coil. The resistor bleeds off the charge of the capacitor when positive voltage is removed from the other side of the coil. You can increase the output time by simply changing the value of the capacitor. This one will give you about a 1/2 second output.
    Seems easy enough. I just so happen to have a relay laying around. I'm pretty sure I can find the needed capacitor and resistor at RadioShack. Here's where my problems come into play of these is correct for the hook up:
    Option 1
    12VDC+ (ignition) - Pin 86
    12VDC+ (battery) - Pin 87
    Wire A to PWR SW - Pin 85 (after cap and resistor)
    Wire B to PWR SW - Pin 30

    Option 2
    Screw it. Trying to figure these Pins are giving me a headache. Can someone tell me exactly what wires go to what pins:
    12VDC ACC
    Wire A for PWR SW
    Wire B for PWR SW

    I'm also confused as to the physical hook up of the resistor and the cap. Someone describe! Do both the cap and resistor both get indivially hooked to something or are they wired in series... Confused!

    Progress [||-------]
    View my Worklog to see some of my progress.
    Downgraded Progress - Starting with another car... 09/13/06

  • #2
    d_sellers, you have Option 1 wrong.

    Here is the idea behind that circuit in laymenís terms:

    Pin 86 and 85 are the coil on the relay. Pin 87 (the Normally Open pin) and Pin 30 are the relays contacts. What happens is as follows:
    1. ACC Power is produced on pin 86.
    2. Current flows into the 1kuF (= 1000uF = 1mF) capacitor until fully charged.
    3. While current flows, the relay is energized.
    4. Once the capacitor is full, MOST of the current stops flowing (just like charging a battery) and the relay is no longer energized.
    5. While the relay is energized, Pins 30 and 87 is a short circuit, just like the pushbutton on your pc.

    After all that, as long as your relay is a 12volt one and the cap is chosen correctly, you should get an adequate pulse to turn on and off the PC.

    To make the relay turn on, you put your ACC line on pin 86. Pin 85 connect to BOTH the Positive side of the capacitor AND the resistor. The now unconnected sides of BOTH the cap and res go to ground.

    Pin 87 would connect to Wire A PWR SW (as you called it) on the motherboard. Pin 30 would connect to Wire B PWR SW on the motherboard.

    So, if you follow all that, you should be able to construct the circuit.

    However, it likely will NOT work in the way you intend. This is because: you use the ACC line to tell the inverter to turn on. At the same moment in time, this circuit would be trying to tell the PC to turn on. It likely won't work because the Inverter will not have sufficient power ready when the PC is told to turn on. It is possible that if you keep the relay pulse on long enough (but not long enough to force power off) then the PC may still catch the relay pulse and turn on.

    To calculate the pulse time, use the formula time (in seconds) = Resistance (of relay coil) * capacitance (of capacitor).

    For example, to use the supplied value of 1000uF, and we will say that the relay coil has 500 ohm resistance (you would need to find out your relay's coil resistance):
    t = 500 * .001 = .5 seconds (this is a close approximation; in reality it's a little more complicated because of various reasons we don't need to go into).

    It is much easier to use one of the Power Controllers that do all this controlling of the inverter, pc, and amps for you. PM me if you want info for the one I use and recommend.

    14" LCD, EPIA MII-10000, 256MB, Wireless LAN, GPS, CDRW/DVD, ELM Scan,
    200wRMS inverter (for the screen), CarPC Pro v2.4 Power Controller,
    2 12" Pioneer Premiers, Sony 6x9s, Sony Xplode Class D mono block, Pheonix Gold A/B amp for highs


    • #3
      Thanks ColdPhreze. You've set me in the right direction. Your description of how to hook up to the relay was going to be my option 2 but I kept confusing myself as I was trying to figure it out.

      The reason why I don't want to go with a real Power Controller is because I don't want to put the time and effort into something that I am not going to really get to enjoy and will probably replace a year later.

      To find the resistance of the relay, what pins would I need to hit with a multimeter? I think if I shoot for a two second pulse that should be enough time to get everything working.

      Progress [||-------]
      View my Worklog to see some of my progress.
      Downgraded Progress - Starting with another car... 09/13/06


      • #4
        From the Image above.
        85 connect as is.
        86 connect to switch ACC (only if it not turn off during crank otherwise you will have double pulse). Check your car to see if ACC is switch off during cranking.
        78, and 30 each to PWR Switch

        If your car ACC is switch off during cranking, you can combine ACC and IGN to make one out put. Issolate each wire with a diode.

        --car ACC ---DIODE ----> OUTPUT to relay 86
        --car IGN ---DIODE ---/ output to relay 86

        The diode is there to NOT messing up your car electrical system.
        2004 Matrix XR A7N8X-VM/400 AMD XP-M 2500+, DS-ATX
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