>Hi again,
>One of my current PIC projects includes high voltage (+/-100V) supplies
>derived from 110VAC mains.  Recently there was some discussion here about
>isolation vs non-isolation (I am 100% in favor of isolation for this
>application as it can not be totally insulated).  There was discussion about
>using capacitive isolation instead of an isolation transformer.  Has anyone
>done something like this for higher currents (>1 amp)??  I would appreciate
>any pointers or success/failure stories.  Thanks.
>
Hi Mark:

I haven't done it. But I did look into it, for a project that needed only
about 5 mils at 12 volts. And I also investigated the devices from Harris
and SGS that purport to be one-chip solutions.

With the straight capacitive approach, if you do the math for the current
you need, the required cap will be larger and more expensive than a
transformer. Also, the value of "isolation" is primarily that of limiting
the amount of current that would be available to sink into a hapless body
that might contact it. Having one amp available kind of strains the
concept. Too bad you have to have isolation; with the small amount of
voltage to be dropped in your application, a simple 10W resistor for each
supply would probably do it.

Regards,
Reg Neale