dc-dc atx power supply question

Sep 11, 2004 2 Replies
T

I have two of these R100D1205-12TS

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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.



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R

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 complex.

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?

Regards, Bob Monsen

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A

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

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for other stuff like this.

http://www.niftybits.ukfsn.org/ remove 'n-u-l-l' to email me. html mail or attachments will go in the spam bin unless notified with [html] or [attachment] in the subject line.
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