> From: peter cousens <peter@COUSENS.HER.FORTHNET.GR>
>
> Bernhard Schweighofer wrote:
> >
> > What's about a light source (light-bulb connected to AC) and some
> > solar-cells ?  :-)
> >
> > bye
> >
> > Bernhard Schweighofer alias schweigi@sbox.tu-graz.ac.at

to which Peter scolded Bernhard with
> for 1A, get real!!

Lighten up!  I was amused by this tongue-in-cheek suggestion.  When you
consider the few % efficiency of incandescent bulbs, the low (10%)
efficiency of solar cells, the transmission efficiency (<5%) it all
adds up to a ludicrous image of hulking 3-phase supplies being used to
feebly illuminate a few LEDs, albeit at 50KV+ isolation!

Now for my own wacky idea: microwaves!  Use old uwave oven magnetron,
transmit down waveguide (or between parabolic reflectors for that
megavolt isolation), receive in 1/4 wave antenna and rectify using a
swag of hot carrier diodes.

Back to reality, another way of obtaining galvanically isolated supply
is with piezoelectric 'transformers'.  I remember this from the NatSemi
Linear Applications Handbook, but can't remember whether 1A could be
obtained.  The piezo transformer had advantages of very high isolation
voltage and very low capacitive coupling.  The disadvantages are the cost
of large chunks of PZT, fragility, low power-to-weight ratio and
complexity of the HF driving circuitry.

Regards,
SJH
Canberra, Australia