You explained it well, Ray. But to explain my “obsessions” in the use of relays and an external transformer, I’ll put it together.
* 1 – Why a transformer? the controller is not loaded with coil current. the relay load is 30 – 40 mA. load on the solenoid valve coil depending on the model 150 – 250 mA. If we open one or two solenoid valves, there is no problem. However, if we want to squeeze out of the maximum from controller, we often open 10 to 15 solenoids at a time. This is too much, open sprinkler stops working stably and stops responding. In my case, the programs overlap and operate independently at different times in different locations.
* 2 – Failure caused by human error or failure in the field, without the use of relays, the controller fails.
* 3 – it looks good 🙂
I’m sending another photo