> Actually see  3rd schematic here, just leave out the +ve multiplier.
> http://en.wikipedia.org/wiki/Voltage_multiplier

It never even occurred to me to look at WP. I'd read someone
say that negative multipliers wouldn't work because of some
ground reference issue so I stopped looking. Maybe they were
talking about a particular application and I misunderstood but I
didn't think so at the time

> Voltage is less number of diode drops and current is very limited.

I've made a +ve cascade (negative ion generator) and -Vcc and
agree that current is limited. I have several spare PIC pins so could
parallel them or the cascades

Could you comment on what effect frequency has - for example
choice of capacitor value and if the reactance has any bearing

I'll try a cascade and see how it compares with an inductor design,
and report back

I've nothing in particular against inductors (apart from finding or
winding one), and it would mean a lower parts count for a better
output that could be stabilised more easily. For example, if Vee is
more or less loaded depending on the number of active pixels
that might rule out a cascade design if regulation is also loading it

Joe
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