12V lighted switch for ATX conversion

Discussion in 'General Electronics Chat' started by bkr1969, Nov 8, 2011.

  1. bkr1969

    Thread Starter New Member

    Dec 11, 2010
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    I'm converting an old ATX power supply to a benchtop supply. Overall, a very easy project, but I wanted to add a lighted power switch - http://www.radioshack.com/product/index.jsp?productId=2103602
    The power supply is switched when the power supply (green wire on mine) is connected to ground. I placed these at opposite ends of the switch and the power is on/off appropriately. I attached the 12V wire to the center pole of the switch and the power supply fan slows to nearly off and the switch light flickers dimly. If I connect the green directly to the ground pole while the switch is on, the light comes on appropriately and the fan runs correctly. Switching the switch off works correctly too, but when I turn it back on...nothing. What, if anything, am I doing wrong? I've wired other ATX supplies with simple toggle switches with no problem. Am I just not able to use a lighted switch?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Did you read the reviews on the Radio Shack site?
    http://www.radioshack.com/product/index.jsp?productId=2103602

    Three terminals; power, ground and load.

    Apparently, the load gets shorted to ground when the switch is turned off.

    I'm not so sure this switch is going to work very well for your application. I don't happen to have one of those. Apparently, there's a schematic on the back, but it's not very helpful.
     
  3. Evil Lurker

    Member

    Aug 25, 2011
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    Simply put my guess is the light on the switch run off the current flowing thru the switch and the green "on" wire of the PSU simply does not have enough juice to power the light.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    The green "on" wire can't really power much of anything; if you try to power something with it, the supply will turn on.

    I wired up a yellow LED to the standby 5v on my bench ATX, so I'd at least know if it was getting power from the mains; then I connected several green LEDs to the various voltages so I'd have some verification that the supply turned on.

    Just a light in a switch won't tell you a lot.
     
  5. bkr1969

    Thread Starter New Member

    Dec 11, 2010
    16
    0
    That all makes sense. I think I'm going to have to go with a plain switch and a separate LED power indicator.
     
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