Re: gEDA-user: OFF: triac

[John Sheahan <jrsheahan@xxxxxxxxxxxxxxxx>]

John Sheahan wrote:
> If you are trying to modulate the oven power, you will need to generate 
> an interrupt off the zero crossing, and run a timer from that interrupt.
> You (probably want to)  enable for the same fraction of both the 
> positive  and negative half cycles.

sorry for replying to myself - but this is probably very misleading.
You cannot turn a Triac off from the input. It turns off When the 
current thru the main terminals falls to zero.  (Which it does twice a 
cycle for an AC load)

You 'enable' it  to say 1/4 power by waiting ~3/4 of the way after a 
zero crossing, then hitting the MOC with a short current pulse.

And yes, you may have to do the proper power integral to map the wait 
time to power as the voltage is a half cycle of a sine wave and power in 
a resistor is proportional to v^^2 - if that matters.