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>Use a cheap optically isolated scr or triac AC relay. Engineer a signal
>to the micro at the AC line zero crossing. Maintain a number that
>corresponds to the desired intensity level: say, the number of cycles
>out of 128 that you expect to deliver power. Construct an algorithm that
>turns the relay on or off at each zero crossing such the the following
>two requirements are met: 1) the average voltage is zero and 2) the
>number of on cycles are evenly distributed throughout the 128 cycle
>period.
>
>Good luck - Tom Rogers  VP - R&D Time Tech, Inc.


A easy way to determine which cycles to turn on is to use 1 to 255
for the intensity level.  One being the least, 255 being the most.
Then at the start of each cycle, add the intesity level to a register.
If there is a carry, use that cycle.

Bill C.