I am putting together some automation for a garden setting. I need to switch 24VAC solenoids for garden sprinklers. I started looking at standard relays but then saw an open source project using TRIACS. Some more research points toward SSR's. When looking at TRIACS I got incredibly confused by having to work out snubber circuits to combat the dv/dt voltage rise on solenoid turn off. I found the STM ACS120 snubberless, zero cross TRIAC (https://au.rs-online.com/web/p/triacs/6871079/) that I would drive with an opto-isolator. When I looked at the SSR's I found the Panasonic SMD Zero Cross AQH3213A (https://au.rs-online.com/web/p/solid-state-relays/6996512/) SSR. Both seem capable of the sprinkler solenoid current (<1A) but not sure which way to go. The SSR has the opto-isolation built in but not sure if I need a snubber circuit with the SSR. If I do can I just use a 100V bi-directional TVS diode across the load or do I need a proper RC snubber circuit.
I've spent over a week researching this and I'm just not getting anywhere. I haven't done much with AC before and everything I have read about garden solenoids says that AC is the only way to do it due to solenoid core magnetisation if you run DC solenoids.
I've spent over a week researching this and I'm just not getting anywhere. I haven't done much with AC before and everything I have read about garden solenoids says that AC is the only way to do it due to solenoid core magnetisation if you run DC solenoids.