Tom Sgouros wrote:
>
> I don't know if this is appropriate to this list, but the device that
> needs to do it is controlled by a PIC16C65...
>
> Does anyone know of an easy way to control the voltage on a 120VAC line? I
> need to vary the light from some lightbulbs, and I don't want to use the
> standard SCR solutions because they produce artifacts that seem to wear
> the bulbs out faster.
>
> & etc.

I can give you this much of a really good design my brother & I did
years ago:

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.

This will give you an outstanding control of the outout power with no RF
switching funnies and long bulb life. The light intensity won't be
linear with the control number, and there is a specific problem that is
solvable with regard to maintaining the two above requirements in the
face of changing control values. I don't know if I can give any other
details, but if it seems important enough I might be able to find the
old code, decipher it and try to determine how much is too obvious to
protect (I did the work for another company).

Good luck - Tom Rogers  VP - R&D Time Tech, Inc.