[intpx]

Apart from the fact that sprinkler systems are almost always 24VAC and every commercial sprinkler controller I have ever used or investigated use optocouplers/fets/triacs I don’t really have a good reason to get irritated by homebrew designs that use relays, but I do get irritated. I think the irritation comes from wanting to really learn-by-copying how to design these circuits and many hours searching for exemplars and reading datasheets left me pretty confounded (though most of this was during the great supply chain squeeze so I couldn’t find the right combos of triacs and optocouplers ins stock and the datasheets led me to believe that subbing out a non zero cross would probably be a problem, or not being able to find logic level triacs)

[eddyg]

Have you looked at OpenSprinkler?

https://opensprinkler.com/faq/ https://github.com/OpenSprinkler