>1. I've never done PWM on 120V before. Can anyone recommend
>what type/value of semiconductor to use? I'd assume that a
>bipolar or darlington transistor won't be the best choice.
>A reference circuit would be awesome if someone can point
>me to something.

I would think you will need a transistor suitable for the output stage of an
off-line switch mode power supply, seeing the string will be operating at
line voltages. Could be bi-polar or FET. An FET will probably require 10-15V
gate drive rather than be 5V driveable, and will probably require some form
of protection to stop drain-gate miller effect feeding undesirable spikes
back into the micro circuitry, while a bi-polar will require lower voltage,
but higher current drive, and again some form of protection against miller
feedback of spikes.

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