ehsjr said:
Keith said:
The processors are powered off the +12V supply output (the ATX-12V and
EPS-12V specs). That's were the real power is (500W is a little high
though). [...]
That's impressive. I wonder how ugly it would be if you put the 3.3 and
the +12 in series through two high current diodes and tried to run a ham
rig. Any thoughts?
Pretty ugly. As far as I know, the outputs aren't floating with respect
to one another - the +12 V and +3.3 V share a common ground. You might
be able to do it with two power supplies, depending on if the secondary
common is also common to the powerline or not. Alternatively, some
people have opened up a PC supply and twiddled the regulation to boost
the +12 V by a volt or two to run stuff that wants to be in a car.
If you had some time on your hands, you could build a circuit with some
MOSFETs and some huge capacitors. Charge one capacitor off of the +3.3
V, then put it in series with the +12 V. Have another capacitor doing
the same thing, 180 degrees out of phase. Or three capacitors at 120
degrees, to give each cap more time to charge.
Down to maybe 10 m, you might be OK, but below that, the switching noise
from the supply may start to bother you. I know that there are switching
supplies designed for ham radios that are alleged to have more filtering
than a garden-variety switcher.
Matt Roberds