Sciencemadness Discussion Board

Will this PSU be good enough to convert?

batsman - 9-11-2013 at 09:38

Hey, i am going to re-build my old PSU from an old PC to a bench power supply that´s going to be used for various different chemistry experiments, but also for some power LED projects.

I would like it to put out at least 10 A after it is converted. It´s good to have a little bit more then you need, instead of not having enough. I hope it´s possible.

I am not an electrician as you might already have got, but it is probably the output of the unit is the important thing to look for i guess. Right? :)

This is what it say in the sticker.

DC output: 200W

3.3V - 14 A
5V - 22 A
12V - 10 A

-12V - 1 A
+5Vsb - 3 A

If you know what i am talking about, please post a few words and tell me how many amps it is able to do.

Thanx guys! :)

WGTR - 9-11-2013 at 11:34

Your power supply is rated at 200W, and you have maximum currents rated at various outputs. Those ratings can't be met all at the
same time, just as an FYI. In other words:

12V x 10A = 120W
5V x 22A = 110W
3.3V x 14A = 46.2W
-12V x 1A = 12W
5V x 3A = 15W

The total wattage if max current was drawn from each output would be 300W. This isn't a problem necessarily. Just keep this
limitation in mind if you're using more than one output at a time.

If it were me, I wouldn't see the need to modify the power supply at all. That unit supplies the bulk power, much like a standard
transformer/rectifier/filter combination would. I'd provide extra conditioning after this supply, as an external circuit.

For powering LEDs, I'd suggest either using a series resistor to limit current, or more elegantly, using a power MOSFET and a resistor
(google "mosfet current source"). The best way would be to use a switching converter configured with a current-limited
output (google "LED driver").

For basic electrochemistry, an adjustable current-limit is indespensible. It's way more useful than a power supply that requires
you to constantly adjust its output voltage manually to maintain the correct current.

hyfalcon - 9-11-2013 at 13:53

The two 5v lines will be what you want to use depending on the size of your electrodes.

jock88 - 9-11-2013 at 16:45

some stuff on converting computer power supplies at the link above.

batsman - 10-11-2013 at 06:38

Thanx guys, (especially WGTR), you have been really helpful. :) I will check the link out.