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Electronics Switch between molex connectors?

Discussion in 'Modding' started by pyro1son, 26 Jun 2011.

  1. pyro1son

    pyro1son Linux User!

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    I was wondering what is the best way to put a switch between molex (on say an extension) connects to turn lights or fans off on the other side when not needed. If I put the switch on the neutral wires so I haven't got 12v running through the switch, is that a good idea?

    Any ideas welcome!

    Thanks
     
  2. Smilodon

    Smilodon The Antagonist

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    Yeah, that would usually work well. However, make sure that the unit you are switching of don't have any ground connection to chassis. Also, don't do this on units that send signals back to the motherboard or any other equipment.

    But why can't you connect the switch on the wires that carry 5 /12V?

    It's very unusual for stuff like lights to use both 5V AND 12V. However, if you have something that do use both power lines you could use a DPST switch so that both the wires are switched of.
     
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  3. pyro1son

    pyro1son Linux User!

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    Was thinking of along these lines!

    [​IMG]
     
  4. Boscoe

    Boscoe Electronics extraordinaire.

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    If your only using 12v switch the 12v not ground. Just better practice that's all. You will have 12v 'through' it, it has to go somewhere.
     
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  5. Tealc

    Tealc What's a Dremel?

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    I put a switch on the 12v when I did mine. I actually have the switch mounted on the front panel so the wires go around in a sort of big loop with the switch in the middle. I used an old Moelx extension cable that I had with an old fan so I didn't need to hack into my power supply leads. If you want to switch 5v and 12v you could use a double pole single throw type switch that allows you to use one button/rocker to switch two voltages and importantly keep them separate. Of course most lights will run off just the 12v unless you have designed them to run off the 5v.
     
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  6. mvagusta

    mvagusta Did a skid that went for two weeks.

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    If one of the black neutral/earth wires is connected to your pc case, a usb port, or any exposed metal of an external hdd or modem, or even a toaster or the kitchen sink, etc, nothing happens, as all these things are already earthed.

    If either the 5v or 12v are accidentally connected to anything earthed in your house, then you've made a short circuit path from posisitive to ground, so the pc will reset and there's even a chance that you might possibly damage the pc psu.
    If the device you've connected has any exposed earthed areas, and they contact any other earthed object, well then the circuit is complete just as if the switch was on!

    Switching the neutral wire doesn't cause any less power to flow through the switch btw, that's why the black neutral wires are the same thickness as the colored posistive wires.

    If you were powering something with -12v for example, you'd want to switch the -12v, for all the same reasons as above.
     
  7. pyro1son

    pyro1son Linux User!

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    Its to turn off CCFL's and ill take your advice ill just put the switch in on the 12v. Also if anybody knows what is the switch on the CM690 II which turns the fan lights off? Its got 6 pins and I no longer use it for the fan lights as ive changed the fans but i want to use it for the CCFL's.
     
  8. mvagusta

    mvagusta Did a skid that went for two weeks.

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    I wouldn't know any details about your Cooler Master case, but you could easily find out everything about it with any cheap yet very handy digital multimeter :naughty:
     
  9. Tealc

    Tealc What's a Dremel?

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    Maybe that switch is two channels with switch illumination or three channels with no illumination. Or perhaps it's neither of these and works with a microcontroller or something to completely mess up any chances you have of rewiring it.

    Get the multimeter and see which pins go from open (no circuit) to closed (circuit) when you push the button and then solder one wire to one pin and another wire to the other pin and form the loop I mentioned earlier.

    If the switch is illuminated on pressed down you will need to wire up a ground to the switch so the LED/Lamp can get a circuit too.

    I modded a 5 1/4" bay to add my switches for a ghetto look. In hindsight it might have been better with a metal backing with the acrylic mounted on top but meh it's done now.

    [​IMG]
     
  10. Smilodon

    Smilodon The Antagonist

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    It's probably a DPDT switch.

    left and right set of 3 pins are separate switches (just mechanically connected). Center pins are common, and the switch switch between the two remaining pairs.

    (Does that even make sense? :worried: )


    But as MV says, get yourself a multimeter and measure to be sure. (You could make a continuity tester by wiring up a light bulb to a batter and some wires.)
     

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