PC External PSU


I need a power supply to run some PC boards outside of the Computer case, the External daughter board i'm intending to use requires 12v, 5v and 3.3v, I have three buck step down adjustable regulators. (4-38V to 1.25-36V 5A 60W Buck DC-DC Step Down Module Regulator Voltage Converter).

I don't want to use a PC power supply because of it bulk and extra wires. looking to create something neater.

The buck Regulator boards have in +/- and Out +/- Can I connect 3 in+ together to the power supply Positives and 3 In- together to Negative and bridge the 3 out- negatives leaving the 3 out+ to output the necessary voltages I require retuning to the combined bridged out- (Negatives) max 60watts each.

it looks logical but before I start,

the question I wish to ask, will this work or will it feed back and fry every thing?

Thanks for your time.

by Digit01
May 02, 2019

Voltage Converter is transfering DC voltage to DC voltage. Where your input DC voltage? Only solution may be to connect 12VDC of PC power supply out to get 12VDC, then use one converter for 5V and another one for 3.3V. Of course, the 12V DC from PC power supply should have more current than your 12/5/3.3V load together.

by wangwg88
May 02, 2019

Thanks for the reply,

I was intending to use a 18.5v laptop power brick, Via Power barrel plug.

I know a PC ATX power supply would work, but it's a large metal box with lots of unrequired cables.

My worry is that if I combine the grounds on the 3 different regulators, would I get ground looping or feed back between the regulators. causing power spikes.

Output would be by a 5 wire Sata Power Connector which was 3 supplies and 2 grounds.

Thanks for your time, Appreciated.

by Digit01
May 03, 2019

ATX Power supply is not as simple like use dc-dc converters.....they have a lot of specifications and Power good signal....I recommend to read https://www.intel.com.br/content/dam/www/public/us/en/documents/guides/power-supply-design-guide.pdf

by ale.trevizoli
May 03, 2019

I suggest buy it: https://www.aliexpress.com/item/24pin-DC-ATX-PSU-12V-DC-Input-250W-Output-Switch-Pico-DC-DC-ATX-PSU-MINI/32826517978.html

by ale.trevizoli
May 03, 2019

no problem to let 3 regulators work in parallel except you connect their positive pins into a loop.

by wangwg88
May 03, 2019

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