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Thread: Changing an ordinary power supply.

  1. #1
    Newbie
    Join Date
    Aug 1999
    Posts
    1

    Changing an ordinary power supply.

    Is it possible to cut out the transformator of a normal (it be 110 or 220 volt) power supply, and attaching a DC current of 12 or 24 volt (whatever the AC output of the original transformator was), so i dont need other DC regulators?

  2. #2
    Newbie
    Join Date
    Aug 1999
    Location
    Manchester, UK
    Posts
    4
    No i'm afraid you can't!!
    I was thinking of doing this but a friend at work told me there isn't a transformer in todays PSU's.
    They use a few regulators to get the voltage down from 240V to the required +12v, -12V, +5v & -5V.

  3. #3
    Variable Bitrate
    Join Date
    Aug 1999
    Location
    Yorba Linda, CA
    Posts
    323
    Actually, most modern PSUs do use a transformer, not a bunch of regulators to reduce the 110V or 240V down to +/-12, +/-5, etc.

    Modern PSUs are switching regulators which use small multi-tap transformers or inductors wound to work with a certain frequency and voltage, and the whole system is "regulated" by feedback loops and the like.

    This is actually a really simplified explanation of how it all works, but an accurate one.

    Actually they don't operate on AC at all; the incoming AC (be it 110V or 220V) is converted to DC before entering the main stage of the PSU's circuitry. You can apply DC to it and have it work, but it would have to be over 110V or 220V to work.

    You can't use 12 or 24V because the whole circuit was designed to operate in "off-line" mode (aka using high voltage inputs).

    I am designing a 12V input PC power supply using step-down and flyback switching regulator ICs. It's actually very similar to modern PC PSUs, but obviously works off lower input voltages


    --Jason

    http://jump.to/m2pc
    Jason Johnson
    Yorba Linda, California
    http://www.m2pc.com

    MPC Phase IV - *** PENDING ***

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