I've added four hose bibbs around the yard, each behind an electric solenoid (24V). The intent is for supplemental irrigation for new plantings, etc. (attach hose to hose bibb; run hose out to be proximate to the new planting; "program" irrigation system to dispense water via this particular "hose circuit" for the several weeks required to get root system established)
I'd like to be able to *manually* signal the irrigation system that I would like the electric valve engaged (and, later, possibly disengaged!). But, I don't really have a spare conductor to dedicate to that purpose. :<
So, I figure I could *share* the "solenoid drive" function with the "button sense" function.
(remember, this is outdoors in the weather so I'm not keen on putting any electronics out there that won't appreciate the heat, cold, water, sun, etc.)
I figure I can wire a NO button across the valve solenoid (either directly or with some series resistance). Then, on the driving side, sense this "short" when the solenoid is NOT energized (i.e., please turn ON the valve) as well as when it *is* energized (i.e., please turn OFF the valve).[Similarly, I could add a NC button in series and "probe" the load when off vs. on]
Any suggestions as to other issues that would make one of these approaches better/worse than the other? Off hand, the NC in series seems like it would be more troublesome (i.e., if the button failed, the valve is not usable).
Or, cleverer solutions?
(I'll have to characterize the valves - and hope any replacements in the future are similar!)