On Thu, 13 May 2021 16:53:30 -0400, Paul
wrote:

snip

If it's a 12V supply, you can use an ATX supply for that.

I do have one I've taken the main output wires from and just left the
power on lines, with the idea of using it on the printer. And that
would be a bonus as the setup can actively drive a PSU that powers the
bed and extruder heaters and so shut them down in the event of a fault
/ overheat.

The modern ones are double forward conversion, and the 12V
section is separate from the 3.3V/5V section and the other
sections don't need a load particularly (should have better
cross-load characteristic than the old single-transformer ones).

OK.

ATX supplies can be very efficient, so less waste heat to remove.

Noted.

If it's a 13.5V supply, then you're looking at some other
form factor, like ham radio supplies (some of which are linear
and lower RF noise, some of which are SMPS with a bit of hash
on the wires). Now the efficiency can be poorer (like on the
linear), and fan cooling is required for a good result. The SMPS
ones will be more compact, because less heatsink is needed.

The old linear supply was just so I could finish the print job for my
mate Paul. Even though it did get fairly warm after the 90 min print,
the duty cycle was probably 1:10 (after the bed had initially got to
temperature).

I think the very best ATX I've seen, was somewhere around
97% efficient at mid-load. This is state of the art stuff.

https://seasonic.com/pub/media/wysiw...s/Titanium.png

That's good.

seasonic prime fanless tx-700

+3.3V @ 20A,
+5V @ 20A,
+12V @ 58A,

Wow. Shame it's EOL. ;-(

-12V @ 0.3A,
+5VSB @ 3A

That's not an endorsement, but it shows what is possible. I'd
still want some air movement through the poor thing.

Quite, and the printer isn't exactly quiet with 3 other cooling fans
running. A 120mm thermally controlled fan would probably not be
noticed. ;-)

There was a time, when some of these SMPS were only 60% efficient
and the heat used to pour out of them, requiring
a stout fan and associated noise. They've come a
long way since then.

Yup, many of my PC's are passively cooled, as has my WHS been for
about 10 years now. ;-)

Do you know what they mean by 'single rail'?

https://www.scan.co.uk/products/600w...-psu-black-psu

I think I only need 300W on 12V and with the 600W PSUs running around
£45 (new), it's quite a bit more than a straight enclosed SMPSU. ;-(

I need to look back of the spec of this console PSU as I think that
was pretty high power and could be switched remotely.

Cheers, T i m