8' drive on PC troubleshooting

[Gordon JC Pearce]

der Mouse wrote:
>>>...can't you take two bog-standard peecee power supplies and connect
>>>ground of one to +12 of the other and get a 24V rail that way?  I
>>>*thought* the output side was supposed to be isolated.
>>
>>Isolated from the power line != isolated from ground
> 
> 
>>I would not be at all suprised to find that the 0V line on the output
>>side is in fact connected to mains ground.  If that's the case, you
>>fairly obviously can't link 2 PSUs in series
> 
> 
> I just picked up a handy not-currently-in-use PSU and opened it up.
> The mains ground is connected to the chassis; the PC board mounting is
> via metal standoffs, and they rest on solder pads which are connected
> to the output ground wires.  So you are correct - at least for that
> supply, and I have no reason to think it exceptional.
> 
> But you probably could do fine, I'd guess, by just cutting the mains
> ground connection for one or the other supply, as appropriate.

NNNGGHH!!! Danger! Crazy behaviour!

If you're really stuck for a 24V supply, you could try two smallish 
deep-cycle batteries, like UPS or motorcycle batteries.

Gordon.