How do I drive an AC solenoid like that found in a lawn sprinkler valve?

Question

I am looking for a schematic or circuit or part that allows me to drive lawn sprinkler valves.

Sprinkler solenoids are driven by 24 v AC, usually under 0.5 A. I am looking for a part or circuit that can safely drive one.

Answer 1

What voltage are the solenoids?

Answer 2

First, you need 24V AC. You can get that from a step-down transformer.
Then, it would be advisable to protect the lines running to the solenoid, so you need a fuse (1A should be OK if you are driving only one).
Next a switching element, may ba a simple switch if you want to control it manually, or a relay if you plan to connect it to some kind of controller.

Another option would be to connect the solenoid valve to the transformer (with a fuse), and switch the primary side of the transformer to 120V, which you can do with a timer that you can buy at Home Depot.

Lastly it is possible that the solenoid can be driven with 24VDC (you should check the information relating to that particular solenoid). If this is the case, a transistor can be used as a switching element (make sure to add a diode in reverse-parallel with the load to avoid huge voltage transients when switching off).

Answer 3

I agree with Eng helper, excepting the part about operating the valves on DC. An AC only valve may draw an overload of current on DC. Unless they are specifically rated for both modes, I'd stay with 24 VAC.

Answer 4

If your making this yourself, you can probably use a control transformer from an air conditioning/heating system. 24vac. Use a manual switch or timer to activate the solenoid.

Answer 5

i admire ketchup, in spite of the incontrovertible fact that it must be with something. i do no longer like it on my own, i could no longer drink an entire bottle of ketchup, i could throw up. (lol im gagging in simple terms thinking approximately it now!)

Answer 6

I'm not sure what you are looking for.