I have an irrigated pasture with seven zones. I would like to have an eight zone come on when any of the other seven are on. I have a higher performance pump then i did when the system was designed. This is causing cycling. I have a very large pond that i add water to. A solution for me is to have the pond valve come on when any of the seven pasture valves are on. I can control the pond volume with a gate valve. This can be adjusted to keep the pump running without the cycling. How can i activate this pond valve with the others. I have to electrically isolate the other seven so they dont all come on at the same time. I tried using diodes before the solonoids to prevent back feed. This made 1/2 wave DC which was not enough to activate the valves. They just buzzed. Is there a way to do this without using seven relays with 24 volt AC coils. Thanks