Dario Greggio wrote:
> Still, using some "large" resistors (or the large capacitor)
> is not that smaller (and maybe cheaper) than the transformer.

The resistors are not necessarily large.

VOD223T - high current transfer ratio (CTR) optocoupler would start
working with LED current as low as 0.1 mA, I'm almost sure. It should
be easy to achieve that 0.1 mA change on VOD223T at, say, 10 mA
combined peak current of the circuit. 10 mA would mean 3 W peak power
dissipation. The fact that it's sine cuts the power twice, and we use
only half the wave, this would cut twice the power dissipation again.

3 W / 4 = 0.75 W per 4 components would demand 0.25 resistors, and you
could try 5 mA combined current, not 10 mA.

Thanks for the opportunity to have some fun.
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