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Will's 2008 MAZDASPEED 3 (phase 2)

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  • Will's 2008 MAZDASPEED 3 (phase 2)

    Ok as soon as I got most of what I originally planned to do done, I realized I wanted to tear everything up again and add to it. Fun!

    Phase 1, what I originally planned, is covered in this thread. As a recap, from here: here:

    For Phase 2, goals are simple:
    • allow PC to be powered via AC plugged into the car (probably via a power supply permanently mounted in the trunk that can power the PC in parallel with the regular DC supply)
    • allow PC to come on via some kind of wireless, remote start, or otherwise not-from-ACC source
    • pc output to control the ignition
    • IM receiver so that I can remote power the PC up, have it connect to IM, then IM the car to get it to start. Then life will be complete.

    Just starting the planning stages now...
    // 2008.5 CWP MAZDASPEED 3
    // mp3car showoff thread
    // appearance & performance mods
    // computer setup

  • #2
    ambitious, good luck
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    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
    Buy now in the Store


    • #3
      I use one of my alarm AUX outputs to remotely turn on my carputer...I can activate it from my desk in the house.

      I'd also love to have an AC power adapter somehow integrated into my system, but then what about powering my amps? You'd have to devise a way to disable the DC-DC PSU when running on AC or risk frying everything!

      Remotely starting the car...hmmm...
      I have a push button starter, working with the alarms remote starter. It needs 2 ground pulses to activate.
      I s'pose I could use Phidgets to send these pulses if I wanted?


      • #4
        As far as starting the car, yeah Phidgets, Fusionbrain, Make Controller I think are all decent/reasonable options...haven't tried to figure out the exact signaling yet.

        Re the AC power, what I was going to do was:
        get an old desktop PC power supply, AC plug
        power the full-current 12V input of the DC supply with one of the 12V outputs from the AC supply, with a two-pole switch to flip between that and the main line off the battery
        wire the power-on signal for the AC supply to itself, however that works, so the PC power supply comes on whenever its main power switch is flipped on
        connect the the DC supply's 12V turn-on to a two-pole switch then to the ACC line and the 12V output from the PC supply

        Does that seem workable? I think it would all work, though I am sure I can think of something cleverer so that I don't have to flip so many switches. I will be switching the DC supply's turn-on as well from the remote start, so I think what basically is going to happen at the end of the day is that I am going to have an OR logic gate that accepts the ACC line, the remote turn-on signal (can I get a constant?), and the AC supply output, and turns the PC on if any are present. The main DC power supply input will then come from the battery or the AC supply, with a manual switch...

        The alarm aux is a good idea; I don't have a crazy alarm, I just want a remote start, but same idea...
        // 2008.5 CWP MAZDASPEED 3
        // mp3car showoff thread
        // appearance & performance mods
        // computer setup


        • #5
          I used to bench test my carputer this way, in the house...running the OPUS from the 12V rail of the AC PSU...
          However, the AC PSU was HEAVILY worked in the would start to heat up and emit a pretty rancid smell after awhile. Then again, it was a $12 Chinese PSU!
          If the DC PSU doesn't get adequate power, it'll put stress on it as well remember!

          I think your on the right track though...
          Another way you might work it, is to have a relay hooked up to sense when there is AC current, then that would trigger other relays to switch the PC over for AC use automatically...i.e. the mainboard switch and DC PSU ON trigger....

          BTW, the AUX outputs on my alarm can be programmed to be constant or one-shot...


          • #6
            For AC power to the car, there are 120V / 12V converters like the one pictured, which is from a Coleman in-car cooler.

            Click image to enlarge.

            I use it for testing the carPC in the house. I wanted to use it as-is so I could continue using it for the cooler, so made a testing harness by putting a cigarette jack on the power lines to the PSU. I suspect you could use it as-is the same way, and put a double-pole switch on the power lines to your M2-ATX to choose car power or converted house power.

            Coleman sells the plug for $60 (list price), but you may find the cooler with the plug on sale for far less.

            These only put out 5A, but that should be enough for the low-power systems we use. There may be higher-output models available; I chose this one because I already owned it.
            If just enough is really good, then too much ought to be perfect.

            2006 Scion xB with in-dash Atom & Lilliput 889GL -- Worklog at


            • #7
              For AC power I think the easier solution at least for me would be to add one of these:

              and have the end hanging out for easy disconnection of the DC-DC and connection of the AC-DC PSU when I'm at home and need to work on the carputer without draining the battery.


              • #8
                Thanks for the thoughts, guys.
                // 2008.5 CWP MAZDASPEED 3
                // mp3car showoff thread
                // appearance & performance mods
                // computer setup