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dc-dc atx power supply question

Discussion in 'Electronic Basics' started by the yeti, Sep 11, 2004.

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  1. the yeti

    the yeti Guest

    I have two of these R100D1205-12TS
    ( I want to use it to run a
    computer on a car battery. Its a 100 Watt, so I think I can do it.
    I'll use the first one to power the motherboard and the second one to
    power the hard drive.

    My 2 questins are:

    1) Can I just use a resistor to step down the voltage?

    2) Do you think I could get away with just using one to power the hard
    drive and the motherboard?

    I realize I have some reading ahead of me to learn som of these basic
    electronics. Thanks for any advice you can give me.
  2. Going from 5V to 3.3V using a resistor will waste about 35% of the
    available power. At 5A, the resistor will dissipate something like
    8.5W, so it'll get hot. A little SMPS would be better, although more
    This depends on the current draw of the mainboard and drive. If you
    are using an EPIA nano-itx mainboard, you might be able to get away
    with it.
    Why not use a laptop, and charge the battery directly?

    Bob Monsen
  3. andy

    andy Guest

    have a look on the via epia motherboard site - they have a mini-itx
    motherboard that's specifically designed to run off a single 12V supply
    only, with onboard DC-DC converters. Also see for other
    stuff like this.
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