I am involved with our church's annual Singing Xmas Tree, where we have
an choir put on a concert in a 6 level
tree shaped pyramid.  We use Xmas tree lights in 4 colors and some
special channels as well, all on dimmers.  Commercial dimmers all seem
to have that 30 volt turn on where you can't dim to or start from '0',
because of the diac diode built in to most dimmers.  I built a 555 ckt a
few years ago, that starts its time period each ac zero crossover and
then C/R times from 0 to 8.33333ms (1/2 of each 60 cycle) and then
triggers a 25 amp triac.  The problem is we now want to remote the
control pots and I now need dc control rather than R/C time constant
control as we want to run the controls ~200 ft away from the
triacs/power boards.  The pic seems like a good vehicle for this.  One
other consideration, I don't mind the concept of running analog wires/dc
voltage for each control if it is much simpler, but it seems to me, I
could run RS422 signals as well on two wires.  Rather than re-inventing
the wheel (fun but takes time), can any of you help me.  Surely this has
been done many times before - theater lighting etc.  I have no problem
with the electronics, making PC boards etc. but don't (yet) have much
pic experience.  Tks for your time.

Mike Montaigne

>----------
>From:  XYGAX[SMTP:XYGAX@AOL.COM]
>Sent:  Monday, January 12, 1998 4:46 PM
>To:    PICLIST@MITVMA.MIT.EDU
>Subject:       Re: Mains lighting control
>
>Tim
>Phase angle control is the easyest way to control the volume of a light
>(incandessent) if you need to use flouressent then consider the HF ballast
>from phillips they take a 0-10v signal same as many commercial dimers.
>
>A consideration with phase angle control is the ammount of noise radiated and
>conducted this needs to be controled with capacitive and inductive filters.
>
>Low voltage lamps were described in a recent mchip seminar using pwm and a
>single FET these make a simalar ammount of 'noise' but due to the switching
>frequency it is simpler to filter.
>
>Cheers Steve.....
>