I have a large irrigation system already wired, and now need to add a few zones (adding more wires is $$). My first idea is to power the valves using DC. Each valve could have a diode in series with it, and a 2nd valve next to it could have an opposite polarity coil.
Power the pair one polarity to get valve 1. Opposite polarity to get valve 2.
I measured the current of the valve solenoid at 24VAC at .2 amp. At DC the valve trips around 5V at the same current.
To accommodate long wires, I might use a current source. will also add a flyback diode across the coil.
Anyone see any issues?
wire corrosion due to DC?
solenoid turn into permanent magnet over time?
long term failure of solenoid?
thanks in advance.