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Topic: Using an old PSU to power motors (Read 2 times) previous topic - next topic


Not all PSUs need a draw on 5v to turn on... a PSU I ripped out of some dell PC from 2006 or so powers up just fine with no load.

Terry King

The situation I recall is that the +12 supply is not good for very much current unless the +5 supply has some load.

Maybe someone who knows the schematic can tell why??
Regards, Terry King  ..On the Red Sea at KAUST.edu.sa
terry@yourduino.com  LEARN! DO! (Arduino Boards, Sensors, Parts @ http://yourduino.com

Ran Talbott

I'm fairly certain that the problem with many of those older multi-voltage supplies is that they used the 5V supply as a reference for the 12V supply, and that the 5V supply was of a cheaper-to-make design that didn't regulate well unless loaded to 10 or 20 percent of its rating.

I think the reason newer PC supplies do better is that they have to be designed to work in "sleep/standby" mode, and keep the 3.3V and 5V supplies under control even when very lightly loaded.  As a result, they can't use the older circuits.

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