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Dual Polarity high current OF PSU computer

Discussion in 'Power Electronics' started by mostafa_gordy, Feb 21, 2013.

  1. mostafa_gordy

    mostafa_gordy

    14
    0
    Mar 11, 2012
    Hi....
    what is way to get Dual Polarity +12V -12V high current of an PSU ATX computer ??
    :confused:
     
  2. BobK

    BobK

    7,642
    1,662
    Jan 5, 2010
    You can't. The -12V supply is low current.

    Bob
     
  3. mostafa_gordy

    mostafa_gordy

    14
    0
    Mar 11, 2012
    what is way to boost currentof -12v ?
     
  4. BobK

    BobK

    7,642
    1,662
    Jan 5, 2010
    You could use and isolated DC-DC converter to generate -12V from the +12V or +5V.

    How much current are we talking about?

    Edited: Actually a buck-boost converter will give you a negative output without being isolated, this is even better.

    Bob
     
    Last edited: Feb 21, 2013
  5. mostafa_gordy

    mostafa_gordy

    14
    0
    Mar 11, 2012
    DC-DC converter ؟
    buck-boost converter .....
    more explanation....
    simple way ??
     
  6. BobK

    BobK

    7,642
    1,662
    Jan 5, 2010
    The simple way is to buy a +- 12V power supply.

    I will not answer any more of your questions until you answer mine.

    Bob
     
  7. mostafa_gordy

    mostafa_gordy

    14
    0
    Mar 11, 2012
    How much current are we talking about? I need more than 2 amper -12v and +12v for power audio Amplifier
     
  8. Electrobrains

    Electrobrains

    259
    5
    Jan 2, 2012
    Of course you could use two old PC power supplies and put the 12V positive outputs in series. That would give you the +/- 12V supply at high current and low (or no) cost.
     
  9. mostafa_gordy

    mostafa_gordy

    14
    0
    Mar 11, 2012
    this way is valid and safe(true way)??please answer me...
     

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  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,192
    2,694
    Jan 21, 2010
    Be careful, the ground could be tied to mains earth.

    Internally however, you could manipulate the circuit to generate a high current -12V supply if you were VERY careful.

    That would make one power supply +12V on the +12V rail, and the other -12V on the +12V rail.

    To do this you need to understand exactly how that power supply rectifies and filters the output and what feedback there might be from this rail.
     
  11. Electrobrains

    Electrobrains

    259
    5
    Jan 2, 2012
    Steve is probably right. I measured a couple of pc supplies and they all had the minus output connected to the metal case (earth).

    Your pictured circuit would work if you only supply earth to the left power supply. The metal case of the right supply would then need to be isolated, because it would be connected to -12V.

    I am not allowed to officially recommend such approach though, because the pc power supplies are intended to be run with a solid earth connected (EMC and security reasons).
     
  12. woodchips

    woodchips

    43
    0
    Feb 8, 2013
    Possible alternative is the 12V PSUs used in the server computers, couple I saw were 40A at 12V, not bad.

    Bob
     
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