I am trying to put together a circuit to automatically add water to my pool when it gets low. The sensor is a 4-20ma pressure sensor. I have a 24 VAC valve to control the flow of the incoming water. What I need is something to go in between these two pieces of equipment. It may be a couple things, I don't know. I basically need something to send 24VAC to the valve when it sees a 4 ma signal and then cut the power when it sees a 20 ma signal. I would like to plug this into a standard 110V power outlet. Can anyone help me out?