I’m bumping this old post up because I have a similar need. There may be other threads that cover the concept, so please direct me if you know of any. I’m not coming up with the right search terms for a better hit. Has anyone come up with a method for controlling more valves that they have wires to drive directly in the valve box? I ditched my old sprinkler controller because it’s limited to 6 zones and I’ve added a couple more, but I also don’t have enough strands of wire in the valve boxes to support the additional zones. I could run the wire, but I’m hoping for a “cleaner” solution. I’m kicking around a couple of ideas for adding zones, but my electronic design knowledge is weak enough that I’m not sure of the feasibility.
One idea would be to put a small board with a serial to parallel shift register, voltage regulator, and SCRs in the box, and send the power, clock, and serial signals down the existing wiring. I don’t know how feasible this is. Would the attenuation in the sprinkler wire be too high to get a clean clock signal? I don’t know how sensitive shift registers are, or whether there’s a common strategy for cleaning up the clock signal at the remote end of a long run. I’m sure there are other problems with this plan that I’m not anticipating.
How about a wireless remote controller, such as an Arduino Yun? Or possibly a wired Attiny board that can process a serial signal and break it out to drive the valves with mosfets or SCRs? I’ve got some DigiSpark Digistump boards I bought on a kickstarter I could conceivably use. Have any of you solved a similar problem or know of a non-OSPi project that I could leverage or learn from?
Thanks in advance,