OpenSprinkler › Forums › Hardware Questions › Choosing the right coil › Reply To: Choosing the right coil
It looks like 2 (12VDC) and 3 (24VAC) should work fine with OpenSprinkler DC. 1b should also work fine, although it uses more power than 2. Yes, I believe that you can drive these with 9VDC (1amp) power supply that comes with OpenSprinkler DC. Generally these valves require a high inrush current to open, but once it’s open, the voltage required to stay on can vary over a wide range. So 9VDC to power 12VDC valves should be fine (and OpenSprinkler DC has internal booster to provide high inrush current needed).
If you need to open two or more such valves at the same time (note: simultaneously), you may need to upgrade the power supply to 2amp or more to provide additional current capacity.