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  • Idea for your own shutdown controller.

    Okay, I haven't done this yet, but I will soon. Hopefully this will work.

    My plan is to create my own shutdown controller using the following:
    - Current car battery
    - Power inverter
    - Computer power supply
    - 1 Relay switch
    - 1 Momentary push button

    I want it to work this way. I will push the MOMENTARY PUSH BUTTON which will quickly triger the RELAY SWITCH to turn on my POWER INVERTER which will then wake my COMPUTER on power restore.

    Now I have already tapped into the computer's power supply to be able to then run a current from the power supply to sustain the relay at which point, the momentary push button will no longer be necessary.

    Here's what I'm not sure about.
    1) How long would I have to hold the momentary push button for it to wake the computer? and could i fry the relay if power is coming from the momentary push button and the PCs power supply at the same time?

    2) I've encountered problems with computers before where if the power is restored, somehow the setting to wake on power didn't work..

    What do you guys think?!
    Carputer Installed.http://www.cardomain.com/id/norek

  • #2
    Don't do it.

    1) It won't fry the relay. If you power the relay from the car battery via the momentary, that's ~14.4V. Connecting that directly to the relay coil which is also connected to the PC regulated 12V would send ~14.4V into the PC and fry everything in the PC running off the 12V. Learn about diodes first.

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    • #3
      I was thinking about making my own using a voltage comparer circuit incase the battery goes flat (using a capacitor to surive the crank) and two seperate momentry relays that simulate pressing the power buttom when the ignition is turned on and off.
      So far - 1.1ghz athlon 4 Sharp Laptop, 256mb RAM, 20GB HDD, 32MB on board graphics. CDRW/DVD, 600W Boschmann amp, K301 InDash Screen

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      • #4
        You would need at least an 8 farad cap (this was just discussed in an earlier thread). Search for "Tank" and "fake ups" and you'll find something better. The MP3Car store sells SDCs that will do everything you need though.

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        • #5
          http://www.mp3car.com/vbulletin/show...t=ups+inverter

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          • #6
            no the capacitor is to keep the illusion of 12v over the voltage comparer.. it would be very low current so would only be small.
            So far - 1.1ghz athlon 4 Sharp Laptop, 256mb RAM, 20GB HDD, 32MB on board graphics. CDRW/DVD, 600W Boschmann amp, K301 InDash Screen

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            • #7
              I designed/had help with this design a few days ago. The circuit turns on with the car - and will power the inverter. My computer turns on automatically when it receives power.

              It keeps power going whenever the ACC is on, or the PC is on. When you turn your Car off - it powers the power button - to turn it off - once it's off - it cuts power to the inverter, The only problem is if it hangs on shutdown/hibernate.
              Attached Files

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              • #8
                Raynmt I've done the comparator thing. Something like an LM311P will run on a single variable source no problem. My first design just buzzed the relay because there was no hysterysis. That can be fixed with a resistor between output and reference so the reference (-) goes up when (+) goes high. That's with the relay on when high, so it doesn't matter how low the voltage is when off. After all that though, I prefer a nice schottky diode from the standard tank idea for quick drops. Now I'm thinking about replacing everything with a heartbeat monitor that I saw in a thread about a week ago. Just can't find it. It was like using a 555 in a missing signal detector type circuit but with about a 10 minute time, and would get a pulse from the ACC going on to start it and close the relay, then the PC would pulse maybe every minute. That would give it time to start up and shut down.

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                • #9
                  You talking about this? >

                  http://www.mp3car.com/vbulletin/show...t=45304&page=2

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                  • #10
                    Yeah, that was you Chris! Like that but slower, like up to 10 minute timout on the pulse to give it time to boot up or shut down. Sort of like those PIR light switches. I like the idea because youl have some flexibility in software and still have safety from hanging and killing the battery.

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                    • #11
                      Ah you know me, the one always with a good idea

                      The good thing about it is that, if this was to be integrated to a SDC, the SDC controller doesnt have to wait for a long time before it realised that a crash condition had occured. This way the SDC can kill the power instantly when the user had requested a shutdown but it crashed. Of course there still an emergency powerkill after 5mins just incase.

                      Keep us updated with your finding.

                      Did that tank circuit and OPAMP thing worked well for ya? oh by the way call me rick

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                      • #12
                        The comparator? No, it sucked. There's really no point in running the battery low when the PC is hung. Having a heart beat would do the job and cut it off faster. The reason I don't want to use a standard SDC is because I'd rather have my usual options when ACC is lost. It pops up a window with a 10 sec timeout that asks if I want to wait another 10 mins or just ignore it when I'm in the garage.

                        The only problem I see now is getting a 555 to wait that long without a large cap and the 555 is like 20 years old. Any ideas for something different?

                        Edit: Never mind, 3-4 minutes would be reasonable. 470uF/470K would work and stay radioshackable.

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                        • #13
                          My Car Computer surive the crank with using one farad cap

                          zachary

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                          • #14
                            Originally posted by joshthepilot
                            Well thats a big waste of space.

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                            • #15
                              I don't mean to hijack this thread (or to take credit for the idea, it began as Chris'), but I thought it would be worth mentioning that I can give you the heartbeat monitor on our shutdown controllers, if anyone is interested.

                              The reason I don't want to use a standard SDC is because I'd rather have my usual options when ACC is lost. It pops up a window with a 10 sec timeout that asks if I want to wait another 10 mins or just ignore it when I'm in the garage.
                              Well, you could just set a 10min acc shutdown timer in configuration settings, and every so often turn the key on for a few seconds, then back off. If you do nothing, it will eventually turn off the PC. You don't get a notification, but it will work.

                              KyferEz
                              TheCarPCStore.com - Power Controllers (SDC), Inverters, Tank Circuit, GPS, OBDII, CarPCs, and more!
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