Marshall Brown wrote:
-------------------------------
As the load is purely resisitive it would be very simple to use phase control with an opto coupled triac (better than an SCR (in my humble opinion) as they self commutate at the 0v crossing - from what I remember, just not as high in the current rating) then you could control the temperature very consistantly by varyting the phase angle, no switching noise either as it is at the 0v Crossing that you turn the triac on.


Both turn off when the CURRENT passes through the zero point. The main difference is that an SCR will only conduct in 1 direction where as a triac will conduct both phases.

Varying the phase angle is exactly that. You are not firing the device at 0 cross, you are firing somewhere in the phase angle.