OT: switching power supply

[Fp-www.Tonepad.com]

I have the need for 24VDC at 6 or so amps.

I am currently using an old PC power supply to get 12VDC for the same application, but I need 24.

My question is: can I use two PC power supplies together by connecting the ground of one and the 12vdc of the other (much like connecting two 9v batteries to get 18v) to get 24v between the first's 12v wire and the second one's ground?

Can this be done without modifying the power supplies or not?

Fp[/code]

[R.G.]

Use your ohmmeter and find out if "ground" is connected hard to the AC power line saftey ground. If it is NOT, then you can stack two of the power supplies for 24V. If it IS, then you cannot - one of the supplies will be shorted by the connection of both "grounds" to AC safety ground.

[Mike Burgundy]

Depends.
Are the supplies referenced internally *in any way* to mass? If so, this won't work without serious tricks. If not, it'll probably work.
It might be easier to rebuild the power suppilies to a +12/-12 system though.
Switching supplies are wierd beasts to us pedelheads, but once you get them down (I'm still short of halfway) they're very cool.

[sir_modulus]

Well ps's usually have 12 and - 12 to work with, so you can use that. Do not fiddle around with the grounds unless they are ATX power supplies. AT power supply can be damaged when you try and chain things inside of them. Don't know too much, but know most ATX ps's have 12V at high amp headroom and -12 at low amperage.

[Fp-www.Tonepad.com]

Thanks for your replies.

I need some 10A current (driving stepper motors)

I found these:

http://www.qsl.net/i0jx/pcsupply.html

http://www.qrp4u.de/docs/en/powersupply/

http://www.fizziker.com/HighVolts/rewire_pwrsup.htm


I'm putting that idea on hold for now. It just seems too much trouble for what a comparable power supply would be worth... I just have a few AT power supplies lying around.

Fp

[niftydog]

Well ps's usually have 12 and - 12 to work with

but the +12 is rated around 5-8A, the -12 is rated at less than an amp.

I'm thinking two car batterys...

[sir_modulus]

good thinking with the battery niftydog,but a car battery is about the same price as a cheapo atx powersupply. Get one that is ratedfor like 450W or so, so that it says the 12V line has at least 14 to 17 AMPS and the - 12 to have some amperage(like 1 or 2 amps). don't use AT power supplies as i have heard that they are very stingy to being connected.

[brett]

good thinking with the battery niftydog,but a car battery is about the same price as a cheapo atx powersupply.

Instead of car batteries, try smaller gel cell batteries.  I got a 7Ah one for about US$10 a while ago.  (Combined with a preamp/tone stack and little car amp from the pawn shop, it makes a nice portable amp).

good luck