Modifying an old ATX power supply - can it be done?

Discussion in 'The Projects Forum' started by cykotek, Aug 11, 2012.

  1. cykotek

    Thread Starter New Member

    Dec 27, 2011
    2
    0
    Greetings all.

    I have a project underway, and would like some advice/assistance.

    Basically, I am trying to create a 12A 30A power supply from an old ATX PSU. This is intended to run a pair of 12V car fridges from a mains power source.

    I know I could buy one pre-made, but they cost hundreds of dollars, and I have the ATX PSU sitting around unused.

    I could easily power one fridge from the 12v rail of the PSU, it has a high enough current rating. I was wondering if there was some way to modify the 5v rail so that it output 12v instead. It doesn't matter if I can't tie the original 12v rail and the new, modified rail together - I could run each fridge off a separate rail.

    Could this be done?
     
  2. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    To change the output voltage of a power supply like this, you need to alter the feedback (PWM) circuit of the driver IC..... what is the ratings of your ATX power supply for the 12 volt rail??
     
    Last edited: Aug 11, 2012
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Usually, computer supplies just regulate one of the voltages (typically +`5v). ATX supplies are so cheap that it would't be worth your time to try such a mod.

    Http://www.mpja.com is one of my favorite suppliers; they carry a large assortment of computer supplies. Have a look.
     
  4. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    10A is the max. you can get out of ATX supplies, and it will drop down to 10V.

    100s of $ for a 30A transformer?
     
  5. paulktreg

    Distinguished Member

    Jun 2, 2008
    612
    120
    Modern ATX power supplies can put out 100A plus and maintain regulation on the 12V rail. ;)
     
  6. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    Are there any 1.2 kW ATX supplies? The strongest I am aware of = 800W but that is high end. Normally they only have 450W at max.

    You can't get 100A from 450W. And it is distributed. Not all the Watts can be drawn from one voltage.

    Old ATX = 200W to 300W. Old = 5 years.
     
  7. paulktreg

    Distinguished Member

    Jun 2, 2008
    612
    120
    Corsair AX1200, 100.4A on a single 12V rail and there are many more!
     
  8. panic mode

    Senior Member

    Oct 10, 2011
    1,321
    304
    hmmm quite a bargain at £205.34
     
  9. Paul Kerry

    Member

    Jan 9, 2012
    36
    4
  10. cykotek

    Thread Starter New Member

    Dec 27, 2011
    2
    0
    Wow... that is insanely cheap.

    Unfortunately, the shipping cost would be more than the item cost (I live in Australia).
     
  11. bertus

    Administrator

    Apr 5, 2008
    15,649
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