Re: Controlling Holiday Lights

[sylvan butler <ZsdbUse1+noZs_0610@xxxxxxxxxxxxxxxxxxxxx>]

On Mon, 23 Oct 2006 23:33:59 -0400, Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx> wrote:
><ZsdbUse1+noZs_0610@xxxxxxxxxxxxxxxxxxxxx> wrote in message
><slrnejqljo.a3i.ZsdbUse1+noZs_0610@xxxxxxxxxxxxxxx>:

> Then please do post how you chose 1000 hz.

With 1000hz I can smoothly synthesize any waveform from D.C. up to 500hz
and of course squarewave up to 1000hz.  Then the interface electronics
will allow me to use D.C. lights (with a class-D amplifier) or A.C.
lights (with a triac or SSR).

>>Think of it as me building a DMX512 or X10 dimmer.  How does it actually
>>create the varying intensities?  By turning on and off the light many
>>times per second.  That's what I'm doing.

> No.  DMX512 does not "turn[] on and off the light off many times per second".

DMX doesn't, but the DMX dimmer does. That is EXACTLY how EVERY SOLID
STATE DIMMER works.  Even a DMX dimmer and same with an X10 dimmer.

Read http://home.howstuffworks.com/dimmer-switch2.htm if you don't want
to believe me.  (microprocessor controlled dimmers simply replace the
analog R.C. timing circuit with a digital output pin)

> If you are turning ON the light many times per second, how do you synchronize
> with line frequency?

I don't.

> If you don't, what happens if you turn on the light when
> it happens to be at 0 or 180 degrees compared to when it happens to be at 90
> or 270 degrees?

When gate (trigger) current is available for the triac, it will conduct
the A.C. waveform.  When gate current is not available, it will not
conduct beyond the zero crossing.  Basic electronics.

sdb

--
Wanted:  Omnibook 800 & accessories, cheap, working or not
sdbuse1 on mailhost bigfoot.com