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Convert comp PS to variable

Discussion in 'Electronic Design' started by Robert Darrens, Feb 25, 2005.

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  1. I have a two good quality AT computer power supplies (Ipec) and would
    like to convert them to variable power supplies for bench use.

    Is this a simple as wiring an LM317 type circuit to one of the 12V
    outputs?

    Secondly, is it possible to add the outputs for more voltage?

    For example, the 5 and 12V outputs in one unit or the 12V of two units
    in some kind of series arrangement.

    Thank you for any suggestions.

    Robert
     
  2. mike

    mike Guest

    There are exceptions, but generally, a computer supply makes a lousy
    bench supply.
    If a LM317 will do what you want, it's easier to start with a small
    transformer and skip the computer supply altogether.
    You might get better advice if you stated the voltage/current ranges you
    need along with other specs like what kind of current limit you need,
    temperature stability, line/load regulation, noise you can tolerate, etc.

    Computer supplies make great...computer supplies.
    mike

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  3. Guest

    I don't know the specifics, but as I understand it a computer supply is
    designed to work at some minimum load, otherwise they tend to be fairly
    lousy supplies. So unless you want to drop 50W or whatever across a
    resistor, it's not a good idea.

    Chris
     
  4. Tim Wescott

    Tim Wescott Guest

    Marlin P Jones, and All Electronics IIRC have very nice 120V in 12V out
    switchers that are actually designed to put out substantial power it
    12V. They're surplus so they're not too expensive.
     
  5. Tam/WB2TT

    Tam/WB2TT Guest

    Generally the minimum load has to be applied across the +5V output. The
    reason for this is that the feedback is taken from 5 Volts. Supposedly,
    *some* supplies will work with a load of as little as 1 Amp.

    Tam
     
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