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Author Topic: Using an old PSU to power motors  (Read 2114 times)
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I'm a noob at electronics and would it be safe if I used an old 150w ATE PSU to power some 12v stepper motors? I see its outputs at 12v 4.6A.
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I'm a noob at electronics and would it be safe if I used an old 150w ATE PSU to power some 12v stepper motors? I see its outputs at 12v 4.6A.

Yes, that is a popular source of low cost DC power. You should probably research on how to modify PC power supplies to use in stand-alone mode. It usually involves adding a power resistor across the +5vdc output so that the PS has a minimum load and can maintain regulation.

Lefty

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I'm a noob at electronics and would it be safe if I used an old 150w ATE PSU to power some 12v stepper motors? I see its outputs at 12v 4.6A.

There's also the question as to what the current ratings for the steppers are, as well as how many you are wanting to power (and how many at the same time)? It may be that PSU will work fine (once you mod it) - but without knowing the details of the steppers and what you plan on doing, you may just overload it...
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This will tell you all you need to know: http://www.hobbycnc.com/information/downloads/
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This will tell you all you need to know: http://www.hobbycnc.com/information/downloads/

In my experience that is a little overkill and hard-to-find resistors.

I connect a 12V automobile taillight bulb (Has 2 filaments, wire in parallel) across the +5 supply. Draws enough current so the +12 seems fine..  Did this on both AT and ATX supplies.

On the supplies I made look cool with a front panel with banana jacks, I put the bulb in a hole and it's the "Pilot Lamp"..

...works for me...
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Regards, Terry King  ..On the Red Sea at KAUST.edu.sa
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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.
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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??
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Regards, Terry King  ..On the Red Sea at KAUST.edu.sa
terry@yourduino.com  LEARN! DO! (Arduino Boards, Sensors, Parts @ http://yourduino.com

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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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