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How to wire up accessories?

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  • How to wire up accessories?

    OK... I have many (4+) 12v accessories that i need to power. I want them to come on when the head unit comes on. What would be the best route for this?

    i was thinking i'd go with: 8ga wire -- fuse holder -- fuse (20 or 30amps) -- 30amp relay -- distro block -- wires from distro to each unit. is that the best way?

  • #2
    If they don't draw much current, you can use your computer powersupply. The yellow wire in the 4 wire HD/CD things is +12V, and one of the blacks gives you a ground.



    • #3
      I don't have anything installed right now.
      I'm gonna get the LCD installed first. I have the PC, all i need to do is design a case for it.


      • #4
        I wouldn't recommend using your computers' power supply as a source, unless your loads require a regulated source and draw low current.

        Do what you said. Get a relay and have your headunit trigger the accessories. If you didn't want to use the headunit as your trigger, alternatively you could use an ACC point so it will turn on whenever the ignition is on.

        I have my relay triggering off my headunit but I'm thinking about changing it. When I goto eject a CD my headunit, it will turn off, flipping the relay which turns off my computer and GPS; which is annoying.


        • #5
          relay good, psu baad. dig? =)
          My cars


          • #6
            8ga wire -- fuse holder -- fuse (20 or 30amps)
            Why do you need that fuse holder? What does it do? Also, that has to be a DC fuse right?
            Silver 1999 Nissan Pathfinder!
            Completion: [*********-] 90%
            Everything working! Mobile MP3s ROCK!
            LEFT TO DO: Improve power on circuit, fix slow boot time

            - 550mhz PIII on Abit BH6
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   Redesigned, new pics!


            • #7
              the fuse holder is to hold the fuse... the fuse is so my damn car doesnt go up in flames!!!

              and for everybody that was wondering, here is what i picked up at radio shack. I realize i could have gotten better deals elsewhere but oh well...






              • #8
                Originally posted by bombboyer
                Why do you need that fuse holder? What does it do? Also, that has to be a DC fuse right?
                IIRC there is no differentiation between power types when it comes to fuses. Power dissipation is P=IIR (I-squared-R) or the square of the current times the resistance. So if you have a "30A" fuse, it means that the power dissipation (heat) will reach the melting point of the metal and break the link, thus not causing the wiring itself to reach melting point and possibly catch fire. Also notice that the power dissipation doesn't use the voltage in the formula, so a 30A fuse is pretty much a 30A fuse.

                (Well, actually, you do have different voltage ratings, but I'm not really sure why... anyone know?)
                IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.