ATX to Lab Supply PTCs

Discussion in 'The Projects Forum' started by blah2222, Feb 7, 2013.

  1. blah2222

    Thread Starter Well-Known Member

    May 3, 2010
    Hi all,

    I managed to get my hands on a solid ATX PSU and wanted to convert it to a lab supply for electronic projects and what not. It has all the rails I would ever need but my worry is that the current capability is a bit too high for my liking (up to 40A for the 5V rail and 38A for the +12V rail).

    I was looking into placing PTC fuses in series with all rails with a trip current of around 0.5A to 1A as I really don't need too much power for what I'm doing.

    Does anyone have any recommendations for PTCs for this or another means of doing the same thing?

    P.S. Silly question, but if all my rails have fuses, would the ground wires also need a fuse as well, being earthed and all...?

  2. takao21203

    AAC Fanatic!

    Apr 28, 2012
    Get a laptop PSU, 20V, 3A, $10.

    Use a LM2576 to produce your voltages.

    ATX supply always has a fan spinning for instance.

    Well-Known Member

    Mar 1, 2012
    the devices you run from the supply will only use as much current as they need. There is nothing wrong with having 40A to work with.

    You can also use that amount of current and convert it to a higher voltage at a lower current for other projects if need be.
  4. blah2222

    Thread Starter Well-Known Member

    May 3, 2010
    Yeah, I know that it won't be an issue for the components that I am using, but in the event that I accidentally short something or make contact with something, I don't want it blowing up in my face and smoking up the room.

    Kinda making it dummy-proof for myself haha...
  5. blah2222

    Thread Starter Well-Known Member

    May 3, 2010
    Are 1A PTCs a good idea or would they be too slow if a surge of >10A hit?
  6. RayInMS


    Dec 12, 2012
    I use 1A fuses in mine. They seem to work fine (though I haven't done any projects that pulled anything over 500ma yet).