Ian Bird has just added some great info and pictures to his site about his irrigation system…
“I built a small relay board especially for the job so there are six small DIL relays on it that control the valves. These are fine for the current drawn by the valves. 5 volts running through the HV output ports trigger these relays on or off depending on the state of the port. In turn they handle the 12 volts necessary for the valves by way of Cat5 cable. One pair within the Cat5 cable is plenty to carry the current drawn by the valves. I have used one pair as the ground return and single wires for each valve. This lets me control the 6 valves from one Cat5 cable. Logic in the programming only allows one valve to be on at once so no current problems there. Making the relay board was easier than doing the plumbing bit which was simply plain fiddly.”
I remember this topic from when I did my first irrigation. I went a slightly different route but this solution would suit my next project to a tee. sadly mollyology has gone, any chance of a revisit of the whole article?