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using wal wart to make variable voltage power supply

Discussion in 'Power Electronics' started by Kerazyugy, Nov 13, 2013.

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  1. Kerazyugy

    Kerazyugy

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    Nov 1, 2013
    Ok guys I'm trying to make a "bench top power supply" my first electronics project

    I have a wal wart (Out31.5v 3.17a) I've been trying to figure out how to use a LM317t voltage regulator but have been told that 3.17a is too much for this regulator i'm hoping to get atleast 24v at 3 ohms at a max .... (im only going on these figures based on some googleing about what you should have as a frist psu) is there a way of doing this? or am i asking for too much (note i'm mostly goofing around with arduino stuff some motors led's lcd's sensors and stuff like that....
    thanks in advance
    p.s. sorry if this is a super basic question i am a super noob :)
     
  2. davenn

    davenn Moderator

    13,933
    1,981
    Sep 5, 2009
    hi there

    have a look at a LM338 regulator instead, use the metal (steel) cased TO3 style, its a 5A adjustable regulator :)
    make sure you mount it on a decent heatsink!!


    Dave
     
  3. BobK

    BobK

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    Jan 5, 2010
    Did you really mean 24V at 3 Ohms? That would be 8 Amps. Also, that must be one massive wall-wart if it outputs 31.5V at 3.17A.

    Bob
     
  4. davenn

    davenn Moderator

    13,933
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    Sep 5, 2009
    naaa I'm pretty sure he meant 24V at 3Amps :)

    Dave
     
  5. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Ohms, Amps, what's the difference?

    Bob
     
  6. eKretz

    eKretz

    251
    27
    Apr 8, 2013
    LOL, probably more like a floor wart.
     
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