Eisermann, Phil [Ridg/CO] wrote:

> > Are you thinking on "free wheeling" during this 10-20 min period
> > without further zero-crossing detection ?
>
> No, i would still detect the zero crossing. But I would not
> re-calculate the length of the pulse. I would think the internal
> oscillator would not drift enough in this application to deviate
> more than a few usec.

Well, "a few usec" is a very short time when talking about 50/60 Hz
AC. After "a few usec" I'm not sure there are enough voltage/current
to keep a Triac conducting. Anyway, we still don't know *what* you
are triggering :-)

And the intosc will more probably "jitter" in the sort run, and
maybe drift (depanding on the temp, this should be mounted
outside, right ?) in the longer run. But in 10-20 minutes, the
temp drift will maybe not be that large.


> Well, that still needs to be fine-tuned, but initial calculations
> indicate a conduction angle range between 120 and 180 degrees. That
> means worst-case I would be firing 60 degrees from zero crossing.

60 deg *before* z-c, not ?
Or 120 deg *after* z-c ?
The 120-180 deg range are the *last* 60 deg of one half-cycle ?

Or did I missunderstand this ?

Anyway, "a few usec" is still very little in this regard.

Jan-Erik.

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