Tks Andy, I printed that out.
Question:
Simple light dimmers are C/R time from '0' crossover to trigger triac.
Theater (analog) dimmers are 0-10V control & 0-10V ramp into comparator
to time from '0' xover.
Even if controlled by DMX or other serial link, still electronically
noisy because of A.C turn-on.
Why not (using micro) always start on '0' crossover and leave out 1/2
cycles.
The more 1/2 cycles you leave out (alternate odd and even so load is
balanced), the dimmer the light.
Would this work?  I've never seen it, but I may be re-inventing the
wheel again.
Comments?
Mike

>----------
>From:  Andrew Warren[SMTP:fastfwd@IX.NETCOM.COM]
>Sent:  Wednesday, January 14, 1998 5:45 AM
>To:    PICLIST@MITVMA.MIT.EDU
>Subject:       Re: Mains lighting control
>
>Montaigne, Mike <PICLIST@MITVMA.MIT.EDU> wrote:
>
>> 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. .... 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. .... 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.
>
>Mike:
>
>Yes, it's been done before; take a look at the DMX512 mini-FAQ at:
>
>    http://waapa.cowan.edu.au/lx/dmx-faq.htm
>
>-Andy
>
>=== Andrew Warren - fastfwd@ix.netcom.com
>=== Fast Forward Engineering - Vista, California
>=== http://www.geocities.com/SiliconValley/2499
>