In mail.pic you write:

>> I am confused by this. Aren't PC power supplies transformerless?
>> Why aren't they dangerous?

>because they do have a transformer between the High Voltage section and
>the outputs :) The feedback for the voltage regulator is also
>insulated, either with a transformer or with an optocoupler.

Oh that's right. They rectify the AC line to high voltage DC and
then chop that at high frequency through a transformer that can
be much smaller due to the higher frequency. I had forgotten.
Thanks!

--
Best regards,
Andy Burgess
aab@cichlid.com