In message  <199612060422.XAA32389@gemini.cc.gatech.edu> PICLIST@MITVMA.MIT.EDU
 writes:
> Well it's the holiday season and like Tim Allen it's time for me to start
> working on my Christmas Lights. I decided this year to soften the chasing
> lights scene and to use fading in and out of different strings. While my
> Motorola MOC3010 type circuits works fine, for dimming I need to detect
> zero crossings. I plan to turn the lights one an off for whole cycles instead
> of trying to triggerfor a portion of the cycle which generates that buzzing
> sound.
>

I did this once, but found flicker at low intensities was too much.

Some quick sums:

  If you go for 6 bits of brightness, at minimum brightness, you
  will have 1 cycle on every 64 cycles, which in the UK (50Hz)
  works out as 1.28 seconds between flashes.


I went over to switching mid-cycle to avoid the flicker.


Regards,



Mike Watson