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  • Momemtary switch to cut all power to comp

    I'd like to use something like this: http://www.mp3car.com/vbulletin/show...erter+shutdown to allow me to cut all power to the computer after I put it into hibernate. The problem is that this circuit requires a constant power feed to tell if it should leave the computer on. I want to be able to trigger this ciruit using a momentary switch (AUX line out on a remote starter).

    I currently have the AUX triggering the POW-ON header on the motherboard - which powers up/down the computer just fine. I want to modify this so that all power to the computer is cut when I turn it off.

    Any ideas? I've killed my battery 3 times now - time to take out a little insurance policy!
    http://www.jeepmp3.com/
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  • #2
    Use a 12v relay that closes when you start up & stays closed until you close another circuit (i.e., the momentary pushbutton you're talking about). The circuit itself shouldn't be too difficult.

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    • #3
      Originally posted by rubicon
      Use a 12v relay that closes when you start up & stays closed until you close another circuit (i.e., the momentary pushbutton you're talking about). The circuit itself shouldn't be too difficult.
      They make something like that? A relay that sticks on or off when power is applied momentarilly?
      Note: The remote starter has to power the computer on *and* off...
      http://www.jeepmp3.com/
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      • #4
        Originally posted by PatO
        They make something like that? A relay that sticks on or off when power is applied momentarilly?
        No, you'd have to create a circuit around it. Something similar to this.

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        • #5
          It may be an EXPENSIVE solution, but have you considered a vehicle immobilizer? When you switch off the engine these throw some sort of relay switch which cuts all power to the ignition until you 'park' the keychain fob transmitter next to the immobilizer to turn the power back on again. IF you wired the shut down/start up controller into the power source at the correct point i.e. the ignition circuit you would lose ALL power to the computer within minutes of shutting down the car and it wouldn't come back on again until you started the car. You'd be adding security to your motor at the same time.

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          • #6
            Have you looked into different carputer starter circuits available? Check out www.dashwerks.com. Their circuit comes with a 30/40 amp relay which may take care of what you are trying to do. Their circuit is very easy to install.
            www.mobile-effects.com

            Free file hosting, picture gallery hosting for installs, PM me.

            Internet's first Front End Skin browser, featured installs, downloads, links, informative articles - all free to registered users.

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            • #7
              Thanks rubicon! That's what I'm looking for. It's making my head hurt right now, but I'll eventually grasp what it's doing...

              vr4 - I don't want the computer to turn on when the key's in the ignition - I want to control it seperately from a remote. This allows me to, for instance, update the software via a wireless link from the comfort of my warm house without going outside.

              SnyperBob - I didn't see anything in the instructions relating to a momentary turn on circuit. All I saw was an ACC wire input... Same thing with the CarPC controllers. Could you... ha ha... throw me a bone?
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              • #8
                You can get relays that latch on or off based on a momentary switch contact. I have some gear that I wanted to be able to control independent of the ignition switch. A simple toggle switch would have done the job, but I wanted to use light gauge wire and a small switch for control. I'm not sure I actually accomplised a lot, but I thought I'd eliminate a little drain on the battery by using a latching relay that doesn't draw current when "on". I got an Aromat ADQ23Q012 relay from Digi-Key. This requires separate momentary switch closures for on and off. I think you can get ones that toggle based on a single switch closure as well if I remember right.

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                • #9
                  Originally posted by Alanh
                  You can get relays that latch on or off based on a momentary switch contact. I have some gear that I wanted to be able to control independent of the ignition switch. A simple toggle switch would have done the job, but I wanted to use light gauge wire and a small switch for control. I'm not sure I actually accomplised a lot, but I thought I'd eliminate a little drain on the battery by using a latching relay that doesn't draw current when "on". I got an Aromat ADQ23Q012 relay from Digi-Key. This requires separate momentary switch closures for on and off. I think you can get ones that toggle based on a single switch closure as well if I remember right.
                  Ahh, that's exactly what I'm looking for!
                  "Latching relay". Thanks for the tip!
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                  • #10
                    Yes, a latching relay is deffinatly the best way to go.
                    I 'cheated' and used a 4throw double pole 5 v relay. I had the momentary switch on one part of the relay, to close the loop to some batterys to 'jump' the relay. the relay catches, gives 120 to the pc, bios is set to on after power resume, gets its power off of the now powered compy, recharges the batts, and makes the switch go to the motherboard's power switch header.
                    I could have done something much more elegant, but it was all I had laying around the house.
                    I would do a diagram, but Alas, I am on the road.
                    Every day driver, 1989 Celica. Probly won't get a carpc for a while

                    Working on: 1972 240z. Gonna put a V8 and a Turion in it. Best power in bothworlds. Now if only I could get my theoretical boot as low as my theroretical 1/4 mile time (8.22 s)

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                    • #11
                      Originally posted by Geking
                      I would do a diagram, but Alas, I am on the road.
                      Drool
                      I'll have to admit, I'm having trouble visualising what you're talking about, but since the parts aren't available at my local ratshack, I'll have to order online anyway. So, I'll take the elegant route and pick up a latching relay....
                      Thanks for the tip though, another solution to a unique problem. Always fun to think about new ways of doing things.
                      http://www.jeepmp3.com/
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                      • #12
                        Originally posted by Geking
                        Yes, a latching relay is deffinatly the best way to go.
                        I 'cheated' and used a 4throw double pole 5 v relay. I had the momentary switch on one part of the relay, to close the loop to some batterys to 'jump' the relay. the relay catches, gives 120 to the pc, bios is set to on after power resume, gets its power off of the now powered compy, recharges the batts, and makes the switch go to the motherboard's power switch header.
                        I could have done something much more elegant, but it was all I had laying around the house.
                        I would do a diagram, but Alas, I am on the road.
                        Well, I've searched, and found diagrams. Been to RatShack dozens of times with no luck. Likely it's due to part numbers not matching up and resistances being askew...

                        Geking, would you care to describe/diagram your circuit with the 4PDT relay? I have one of those sitting around, and have tried building it myself, but can't figure out how to unlatch it with a second press of the switch. I also have two DPDT relays, if that helps...

                        Does anyone else have ideas about how to make a relay latch from a single momentary toggle using the severely limited resources of RatShack? How about a circuit that *actually* works and is in use right now (with parts from the online places)? I think I'm going insane!!!
                        http://www.jeepmp3.com/
                        CarPC Stolen. Starting over.
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                        • #13
                          PatO, that one in your first post would work. It only takes a pulse to get it started. The only thing you need to do is remove the COM port stuff or just don't enable the UPS in Windows and it will stay on forever. To turn it on and off with each press, you could connect another relay to the remote and contacts go to the power button. Off would work, but not sure about on. It would pulse right as it gives power to the whole thing. Do you know how long the pulse is? If it's over about 1 second it should work great.

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                          • #14
                            Yep, I've thought about that circuit, but I don't want to rely on the computer shutdown sequence to turn the thing off. Although, I suppose I could rig up a timer circuit to somehow turn off the main relay... Hmm... At any rate, this momentary latching circuit will compliment that circuit and allow me to use the trunk popper from my remote starter.

                            I've been focusing on a 4-relay setup for a while now (attached) . It seems that the relays are only enguaged while the computer is on, so I shouldn't have to worry about burning out coils (much). I've rigged it up with different types of relays (don't have 4 of one type) and haven't had any success. I just bought 4 micro relays, and will give it a shot now. (fingers crossed)
                            Attached Files
                            http://www.jeepmp3.com/
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                            • #15
                              Okay... So it appears that the differences in relay coil resistance was the problem. Using 4 identical relays worked!

                              And they all stay off when the circuit is off, so that's a good thing.

                              Now, I realize most of you are cringing at my use of relays in this circuit. I am too. In my test of this circuit posted by rubicon, I used a TIP3055 (276-2020) and MPS2222A (276-2009) instead of the suggested 2N3053 transistor. It didn't work. How different can those transistors be? If I compare the specs, I see this:
                              3055 (my closest match)
                              Vcbo = 70V
                              Vceo = 60V?
                              Vcex = 60V?
                              Vebo = 5V
                              Ic = 10A
                              3053 (used in the schematic)
                              Vcbo = 60V
                              Vceo = 40V
                              Vcex = 60V
                              Vebo = 5V
                              Ic = 0.7A
                              So, what does this mean? How should I adjust the circuit to account for the differences between the transistors? It is worth noting that there are no other discrepancies in the circuit, I have all of the suggested resistors, diodes, and caps.
                              http://www.jeepmp3.com/
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