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Old 03-20-2011, 04:54 PM   #1
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Default Converting PC power supply to a bench PS ( 2 12V)

I've converted an ATX power supply for use with as a DC power supply for my chargers in the past, but found another one with a [email protected] and [email protected] (350W) and thought I would convert this one also. I have not found any instructions on what to do with this dual 12V situation. I found this:

http://www.playtool.com/pages/psumul...ultirails.html

which helped explain that this is unlikely to be two independent 12V rails but rather multiple current limited 12V rails off a single 12V rail. It also talks about these having a 20A limit total. If this is the case it mentions putting all the 12V lines together... will this give me 23A or just 20A?

I would like to just put them all together and run to a box with 3 or 4 sets of banana jacks if I can get the whole 20 or 23 Amps. Otherwise I thought of running two sets of lines to the box and split the lines to run 2 jacks off each line.

Anyone have some thoughts or have converted an ATX PS of this type?


Posted this in electronics also but more traffic out here.. . kinda hope for a quick answer so I can finish. Thanks.
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Old 03-20-2011, 08:17 PM   #2
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Originally Posted by padailey View Post
I've converted an ATX power supply for use with as a DC power supply for my chargers in the past, but found another one with a [email protected] and [email protected] (350W) and thought I would convert this one also. I have not found any instructions on what to do with this dual 12V situation. I found this:

http://www.playtool.com/pages/psumul...ultirails.html

which helped explain that this is unlikely to be two independent 12V rails but rather multiple current limited 12V rails off a single 12V rail. It also talks about these having a 20A limit total. If this is the case it mentions putting all the 12V lines together... will this give me 23A or just 20A?

I would like to just put them all together and run to a box with 3 or 4 sets of banana jacks if I can get the whole 20 or 23 Amps. Otherwise I thought of running two sets of lines to the box and split the lines to run 2 jacks off each line.

Anyone have some thoughts or have converted an ATX PS of this type?


Posted this in electronics also but more traffic out here.. . kinda hope for a quick answer so I can finish. Thanks.
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I did convert a ATX power supply that has two rails. Inside the PSU, there is two completely seperate power regulators. Mine is rated for 20A, and 15A.

I converted it as per normal, but removed most of the 12V supply lines, and removed all the 3.3, and 5V lines. Once that was done, i have 4 banana jacks on the outside of the PSU which allow me to access the 2 grounds, and the seperate rails. Works really well, and i have not had any issues. I have not tried connecting the outputs to make a single 35A output.


One thing i did notice about my power supply that might solve your question about current limiting, is when I put a heavy load (say 10A) on output #1, the voltage drops slightly below 12Vdc. The Second out put does not change at all.

I am thinking if they two outputs are connected (same rail, only current limited some how), both of the outputs would drop with only one of the outputs having a heavy load.
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Old 03-20-2011, 09:29 PM   #3
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Originally Posted by Shawn68z View Post
I did convert a ATX power supply that has two rails. Inside the PSU, there is two completely seperate power regulators. Mine is rated for 20A, and 15A.

I converted it as per normal, but removed most of the 12V supply lines, and removed all the 3.3, and 5V lines. Once that was done, i have 4 banana jacks on the outside of the PSU which allow me to access the 2 grounds, and the seperate rails. Works really well, and i have not had any issues. I have not tried connecting the outputs to make a single 35A output.


One thing i did notice about my power supply that might solve your question about current limiting, is when I put a heavy load (say 10A) on output #1, the voltage drops slightly below 12Vdc. The Second out put does not change at all.

I am thinking if they two outputs are connected (same rail, only current limited some how), both of the outputs would drop with only one of the outputs having a heavy load.
Thanks Shawn... I set everything up to do two separate outputs so I can hook it up both ways and see what I happens. I think I'll start with the 12V's combined.
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Old 03-21-2011, 02:54 AM   #4
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Also worth considering:

http://www.rctech.net/forum/radio-el...er-supply.html

Light, cheap and in a nice case. If you use the 203W version you get 17A.

It's what I now use; total cost was 20GBP including a couple of banana plugs.
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