USB Stuff

[Tony Duell]

> There are Middle-era PC Clone machines that are pretty much only useful
> as power supplies.  A few times when I've needed quick-and-dirty 12
> volts I have taken an old clone supply and tapped into the yellow and
> black of a drive cable connector.  The only thing is, the PC switchers
> won't start up and regulate properly without a nominal load on the 5
> volt line.  So  you plug in and duct tape an old 3-1/2" hard drive to
> the power supply and use it as a 'dummy load.'

In other words it's a kludge. Most, if not all, PC power supplies take 
the reguation feedback loop from the 5V output (after all, that's the 
important one in the intended application), the 12V line tracks along. 
And I doubt there's a crowbar on the 12V line.

And then something fails, you don't have schematics, the parts are 
unobtainable, so you grab another old PC power supply and kludge that one 
to work...

Personally, I value my toys enough to give them a properly designed power 
supply. One that I know is regulated from the output I am using, with a 
crowbar, and with proper docuemntation.

-tony