Re: Controlling Holiday Lights

[ddl@danlan.*com (Dan Lanciani)]

In article <slrnek5vme.vse.ZsdbUse1+noZs_0610@xxxxxxxxxxxxxxx>, ZsdbUse1+noZs_0610@xxxxxxxxxxxxxxxxxxxxx (sylvan butler) writes:
| On Mon, 23 Oct 2006 23:42:22 -0400, Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx> wrote:
| > No I am not ;-) What you describe is a very low-resolution way ( max 8 dim
| > levels at 1000 hz) to dim AC power using TRIACS or back-to-back SCRs.
|
| Your prediction of 8 dim levels is without basis or merit.
|
| Assuming 60hz.  Typical phase control the triac must be triggered 120
| times per second at a TBD offset after the zero crossing.  If the triac
| is instead triggered exactly twice as often, it will function exactly
| the same -- the output A.C. waveform will be identical.  Same if the
| triac is triggered exactly 4x as often.  Or 8x as often.  8x is 960/sec.
| If I instead trigger at 1000/sec, that is a max of 4% error when it
| happens at random instead of synchronized to zero crossings.  This error
| has imperceptible effect (to my eye when using incandescent lighting).

What (not synchronized to the zero crossing) triac trigger waveform
will you synthesize to obtain an approximately 50% dim level?

				Dan Lanciani
				ddl@danlan.*com