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can i use two pc psu's to get 24v?

Yesterday i had a great thought for getting my macintosh powerbook 190 to power up. If i used two 12v sources in parallel i could get 24v (i think thats what it is, i mean where one power supplies negative is connected to the others positive and the neg of one and the pos of the other are used to create a combined voltage).

So i tried it with one pc power supply but then i realized the 12v's are all connected to the same circuit so hooking it up like that would just short it out.
I tried with two wall adapters, and on my voltmeter, it gave me around 30v with no load. the only problem is, that it doesn't supply 2 amps worth of power. but the 12v line on a pc psu supplies at least 10 amps, so if i used two pc power supplies (to prevent any shorting out) and hooked them up like described, could i get the 24v @ at least 2 amps that i need for this?

Thanks in advance,
z247


Ted_lens6 years ago
what you are trying to achieve here is doubling the power uitput by putting ur power source in series.. however this does not work with psu's and is dangerous for your hardware.

however, i believe a single psu has a -12 (google for right color) and a +12 wire.(yellow?)

so a single psu would be able to give u 24 volts, however the current (amps) would be limited to the amount the -12 wire gives you (different for every psu) overamp it and you will usually damage the psu.

also, in the long run your power supply might not like this setup at all since it is designed to use +12 with ground or -12 with ground and not interchanged.

good luck and remember, google is your friend :)
NoodleUK6 years ago
What Ted_lens said, although the -12V on a PSU is usually rated for less than 1 Amp, whilst the +12V is rated at 10+Amps.
They won't stack up, i.e. the PSU will give 24V, but only at less than an amp. So long as you're not powering anything beefy it might not matter, but I'd be wary about drawing more than 2A.

steveastrouk is also correct that 2 PSUs will both have a common ground. If you try and make 24V, both 12V PSUs are measuring their 12V from the same '0V'
value, so they will not 'add up'.
You would have to make the ground on one PSU the 12V from the other. I'd never even attempt to do that, I have no idea what would happen but you don't ever want to un-ground something like that and leave it flying.
I would assume that the 0V of the supplies is connected to electrical ground, so you probably won't get away with this.

Steve