# PC power supply Output 24VDC

Discussion in 'Power Electronics' started by Khatana, Jul 17, 2013.

1. ### Khatana

4
0
Jul 17, 2013
Dear all,
I have a standard PC power supply and want to use for my general requirements other than PC.
Its 10 pin connector shows +12V and -12V so can i get 24V out by connecting these two pins.

2. ### BobK

7,682
1,688
Jan 5, 2010
Yes, but the current is limited to what the -12V can supply, which is usually quite small.

bob

3. ### Khatana

4
0
Jul 17, 2013
But it sure that i can get 24v from ordinary PC supply

4. ### BobK

7,682
1,688
Jan 5, 2010
I will let someone else answer since you don't believe mine.

Bob

5. ### duke37

5,364
771
Jan 9, 2011
Why not put a meter between the -12V pin and +12V pin and see what you get?

partyanimallighting likes this.
6. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,496
2,837
Jan 21, 2010
You will get 24V, but it will not be 24V with respect to the ground connection.

Voltage is a difference.

In this case the difference between ground and +12V is 12V, and the difference between ground and -12V is also 12V, but in the opposite direction.

So, the difference between -12V and 12V is 24 volts (12V to get from -12 to ground, plus another 12V to get from ground to +12V)

It's a bit like if you live on a straight road running north-south. One of your friends lives 12 miles north of you, the other 12 miles south of you. Thus they are 24 miles apart.

7. ### Khatana

4
0
Jul 17, 2013
Dear Duke,
I hav'nt supply but suppose to buy but before that want to confirm according to my requirement

8. ### Khatana

4
0
Jul 17, 2013
Dear Steve,
The device which i want to power up will feed 24v regardless of 0 level b/c we directly feed two cables +12 and -12v without any earth connection so i think it does not matter what is zero potential

9. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,496
2,837
Jan 21, 2010
What current does your equipment require and what current can the power supply's -12V rail supply (it's almost universally under 1A)

10. ### BobK

7,682
1,688
Jan 5, 2010
If you intend to buy a power supply, and you only need 24V, why not buy a 24V power supply? It will likely be cheaper and smaller and provide more current than a PC power supply will at 24V.

Bob

partyanimallighting likes this.