Is there a way of driving relays rather then valves?
I would like to use the output to operate other devices before the valve.
I understand my DC version will power DC 12 v valves or 24v ac so reluctant to put a relay on the output before asking as it will obviously do some sort of checking first. I read there will be a high pulse then holding current.
If you have a DC-powered OpenSprinkler, it can drive 5VDC relays or 12VDC relays — for 5VDC relays the default power adapter should work fine, for 12VDC relays, you should change to a 12VDC power adapter (the controller itself can accept any input voltage from 5VDC to 12VDC). The impulse high voltage is generally fine for relays because it only lasts for a couple hundred milliseconds and won’t damage the relays. Also, you can turn off the boosting time (in Edit Options -> Advanced, change Boosting time to 0) to avoid the impulse voltage.
If you have an AC-powered OpenSprinkler, it can drive 24VAC relays.
There is already a TVS diode on each zone for transient voltage protection. Also, if you use a relay module (instead of an individual relay directly) — the relay module’s control pin is generally connected to a opto-isolator, which turns on relay and has built-in flyback diode on the relay side. So if you use a relay module, the flyback diode is already included. In sum, you don’t need flyback diode either way.