I think the smallest you are going to find with ok 5v amps is something like a Shuttle 500w. About 1/2 the size or a little bit less of an ATX PSU.

Are you using an original picoPSU or a Chinese knock-off? The Chinese ones can't power ****. The original picoPSU on the other hand successfully powered a Pentium4, a P233MMX, a 386... all with discreet cards for VGA (not a 3D accelerator of course), sound (SB16), CF card, CD drive, and 2 floppy disks.

Might wanna look at old external 5.25 drive cages, both ones with internal supplies, and later ones, the external power bricks.

wbahnassi wrote on 2025-05-05, 01:20:

Are you using an original picoPSU or a Chinese knock-off? The Chinese ones can't power ****. The original picoPSU on the other hand successfully powered a Pentium4, a P233MMX, a 386... all with discreet cards for VGA (not a 3D accelerator of course), sound (SB16), CF card, CD drive, and 2 floppy disks.

I got a 120w picopsu from minipc.de, I think it's a genuine one.
I need this thing to drive a voodoo 1 along with the other components.

I bought a 120W (red 20 pin ATX connector) fake Pico PSU from RGEEK with reference to max system on pico PSU (and pico PSU problems) and it is working fine with VALUESTAR NX VE35D/67C (PII-350, RIVA 128 onboard).
Given the components installed, it should be able to handle a 5V line load of about 50W without any problems, so I don't think it will be a problem at all with machines from the AT era (except for the lack of -5V).

RockstarRunner wrote on 2025-05-05, 04:50:

I need this thing to drive a voodoo 1 along with the other components.

I think you are expecting a little too much from picoPSU 🙂

wbahnassi wrote on 2025-05-05, 07:33:

RockstarRunner wrote on 2025-05-05, 04:50:

I need this thing to drive a voodoo 1 along with the other components.

I think you are expecting a little too much from picoPSU 🙂

Well, that was the main thing point of my original post, Pico PSU is a bit too on the edge for old systems, and I wanted to know if there are better options that would also be small like that. Is it impossible to design a Pico sized PSU better suited for AT? Seems like it would be a good community project.

Right. I guess the peripherals would only add their real load when activated, so say a floppy drive is reading, and the CD drive is reading...etc. But a Voodoo1 is a continuous load, so it really eats out of the PSU's capacity.

I'm not an electrical engineer, but the starting point would be to estimate the load needed by the config you're going for. Then it would be possible to derive how to distribute the input voltage among the rails.

Consider also that the brick used to power the PSU will need to cope up as well.. which I find it starts to become difficult to satisfy when it has to output 12V with high amps. Laptop bricks go for 19V, but now we miss a clean 12V, so we need more components to get +/-12V in addition to 5V... so the pico design will no longer remain "pico" anymore.

Floppy drive enclosure PSUs are not very good candidates, since they were designed for floppy drive loads. They would be underpowered on 5V most probably.

The best option would be IMO a vintage Shuttle (or clone) PC PSU as mentioned. And even that will go with a bit of luck.

Maybe add one of these DC-DC modules to generate the 5V rail, if there is space inside the system:

300W 20A Step Down Converter (select from the drop-down menu)
https://www.ebay.com/itm/295333172275

There are many other different varieties on Ebay too if one looks around. Price is about $10-13 per module on average, maybe cheaper if you spend enough time to look. You can probably build an entire AT PSU with these - one module to generate 12V, one to generate 5V, and there are also modules to generate negative voltages from a positive voltage rail, so that you can get -12V (and if really needed, also a simple 7905 circuit to generate -5V rail too.) And you can power them from a 19-20V laptop power adapter (or two) if you need more power.

Perhaps something like this would help?

Re: I recently found this hardware, AKA the Dumpster find thread.

DaveDDS wrote on 2025-05-05, 12:29:

Perhaps something like this would help?

Re: I recently found this hardware, AKA the Dumpster find thread.

Thanks for the link, but I'm trying to avoid having a big ATX PSU , and am looking for small solutions.

RockstarRunner wrote on 2025-05-05, 12:44:

Thanks for the link, but I'm trying to avoid having a big ATX PSU , and am looking for small solutions.

I did get that .. just sharing my own experience. .. I had the ATX sitting on the shelf
beside/behine the system for a couple years, then decided to take the time to
"properly" mount on the cover ... it was *MUCH* better and easier once it was all
one unit - I agree that if you can find a small one, that would be bests, but if you do
have to go external, mounting it to the system makes (IMHO) for a much better solution!