> I'm a firm believer that switches should only control lights, not fans.

That is very true. Most light switches will not take the inductive
kickback from even a small (30W) fan for too long.

I have seen a scheme where a small load is powered from the live wire in
two ways: When the load is off, a small leakage through the load is used
to obtain the power. When the load is on, the voltage drop on the switch
is used. The scheme I saw that used this, powered a single blinking led.
This could be expanded easily using a dc/dc upconverter from 1-1.5V to 3
or 5V. The voltage drop in operation was obtained from two bridge
rectifiers 'misused' as four (eight ?) antiparallel diodes. With the
switch off, the power came from a capacitive voltage reducer (Xc etc).
Neat ? Ideally the switcher would work from 0.5V, to use a single diode
drop.

Peter

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