I'm a little bit confused of what two similar components
actually does (and how they are different).
I'm building a little circuit that just controls a 24VAC relay, and I found a old proven construction that does this that was using a MOC3042M. However my local distributor don't have this one in stock so I found one that seem to do the same thing EL3063.
But at the same time I found one that is missing the "zero crossing" but is a little bit cheaper.
So my question is what does that zero crossing do,
and when is it useful?
(feels like I missed something fundamental about triacs?)
Here are the symbols and data about the components:
EL3063 - ZERO CROSS TRIAC PHOTOCOUPLER
EL3053 - RANDOM-PHASE TRIAC PHOTOCOUPLER