On Monday, 5 October 2020 10:02:15 UTC+1, charles wrote:
In article , Dave W
wrote:

Triacs conduct in both directions when the gate is held +ve, so give
full-cycle operation.

er, no. Triacs are diodes. To get full cycle conduction you need a pair of
triacs.

Yes, triacs do conduct in both directions and can be triggered with
either polarity as well. In other words, all combinations of positive
and negative voltage on the main terminals and trigger terminal are
able to trigger conduction using a single triac. The sensitivity can
however vary depending on the particular combination.

John