DIY PC power supply charger
I had stumbled across this instructable article about converting a PC power supply to a multivolt power supply/charger. Since I had a few lying around, I thought I'd give it a go. I pretty much fo...
Forum Discussion
BFL13 wrote:
If you put the 5s in with the 12s to make 17 (not sure how you would actually do that) would that satisfy the requirement so it wouldn't sag? Maybe then I could use my buck converter instead of needing a boost one.
Nope, mine is a 15a so that 23a is a problem--would need to ensure "demand" stays below 15a somehow. It does have a 15a fuse on the input side though.
PC power supplies all use a "common" ground point so +5V and +12V lines can not be "tied" together in series to make 17V.
It would take a lot of serious circuit board rework and engineering to "split" the +12V ground from the +5V ground. Basically all the output voltages are coming from ONE high frequency transformer. 12V, 5V, 3.3V come from "taps" on the transformer.
You could use the -12V and the +5V to make 17V, however ALL the negative voltage outputs in PC power supplies are extremely "weak". The -12V is typically .8A (yep that is 800 ma) to perhaps 1.5A.
The negative voltages use the same "taps" as the positive output but the diodes polarity is reversed. They use lower current diodes for the negative voltages and most likely smaller cap values along with smaller circuit traces. In short it will cost you more time and money attempting to rework the supply than if you simply just bought a supply of the desired voltage and current output.
Since ALL the voltages are developed from the same transformer they simply monitor the 5V line for voltage regulation and all the other voltages will stay within the proper voltage ranges for the given ratings.
