CPU bench power supply, 24v

Probably not. A true bench supply can have two independant outputs with isolated grounds, so you can hook the two supplies together to get double the output - A PC power supply only has one ground and so cannot be bridged.

Hooking the +ve and -ve 12v together will give you either a bang and some smoke, or you will have 24vAC (connecting two half wave signals together? Depends how good the smoothing is I guess) but I'd be curious to see what you get.

>>1059466
The -12v in some supplies has a very small capacity. Check the specs.

>>1059466
Yes, but the device really needs to be "small". The -12V output is pretty weak, sometimes limited to just 500mA or so.

I need 50 mA. Virtually nothing.

Reason I asked is I think I tried this once and it didn't work... So looking for the reason why not. I think this anon answered it... No true ground. >>1059470

50mA... I'll just use a couple 9v batteries... I'm overthinking this...

You could make/buy a little boost converter.

>>1059466
It should work, but the protection on those rails wouldn't funcrion, and you'd be limited to the amps available on the lowest capacity rail.

Just to make sure you know, you would need two of these for the 24v supply...

grab two old computer power supplies - short the green wire to a black to get it going then use blac and red for 12 volt

>>1059473
I've pulled 5~10amps off 24v pretty easily, 240watts EZ probably not for very long though didn't sustain it for too long around 5min, didn't do much prolonged testing, I must admit

If you connect 12v and 5v will you get 7v or just fuck up the insides?

>>1060501
with -12v and +5v you'll get 12+5=17volts

you cant connect two positive voltages and there is no ground and psu will see it as a short and turn off

you can connect any +3.3,+5v,+12v to -12v rail and add them respectively +3.3+-12=15.3v...etc

>>1060708
>you cant connect two positive voltages
Yes you can, running fans at 7v this way was one of the standard ways of lowering fan noise back when PC "modding" was just starting out.

>>1059466
I was planning about doing Great Scott's modular powers supply, looks pretty nice

https://www.youtube.com/watch?v=wI-KYRdmx-E

>>1059466
i managed to do that to test a switching regulator with 1A output but i guess that's up to your's bench's power

>>1060501
So long as you have enough load on the 5V rail that you're still pulling net positive current, yes. If the 12-5V device is the only thing plugged in, you're pushing current into the 5V line, which can cause issues. With a full PC, you're fine.

>>1059473
This.

While possible to get 24V, the current you can draw from it will be tiny because of the low capacity of the -12v rail.

>>1059470
>Probably not. A true bench supply can have two independant outputs with isolated grounds, so you can hook the two supplies together to get double the output - A PC power supply only has one ground and so cannot be bridged.
>Hooking the +ve and -ve 12v together will give you either a bang and some smoke, or you will have 24vAC (connecting two half wave signals together? Depends how good the smoothing is I guess) but I'd be curious to see what you get.

people like you always post in electrical threads. You don't seem like a troll, but your comments are all so full of shit it's hard to believe you are serious.

You know terms like smoothing and half-wave, and yet you don't know the simplest concepts related to DC voltages. How does that happen?

>>1059470
Fucking kill yourself or go read a damn book before coming here with all that nonsense.

>>1061016
Positive rails aren't supposed to be used to sink current, this mod only works because when you have a PSU actually installed on a PC, it's always providing a lot of current to the system. In your case (12V -> fan -> 5V), the 12V rails would be trying to push a couple mA down the 5V rail, but since the 5V rail is providing a lot of current to the motherboard, peripherals and whatnot, the net current would still be "coming out" of the rail.
If you were to do this kind of thing with absolutely no other load connected to the PSU, you would very likely break it.
Doing this with the 12V and -12V rails is okay though (as long as the load meets the rated current), because the -12V rail is design to sink current in the first place.

>>1059768

No, most PSU's have at least -12v, -5v, common, 5v, 12v.


-12v to 12v is 24v

>>1064278
I ran a nicad and SLA charger with the -12 and +5 on trickle, full load for lipos tripped it off tho.
Could pull more current with +12 anyways.