Doubler allows independent control of two automatic valves with only one valve wire and the common. When Doubler is connected to one station of the controller, it switches when the station is turned on and passes the electrical current to the first valve. The next time that station is turned on, Doubler switches to the second valve. It simply alternates between the two valves. If two stations are connected to Doubler by a jumper wire in the controller, it switches between the two valves corresponding to the two stations. It simply uses one wire twice. If a second station is not available, use another program to power the added valve. Each valve will water for as long as the time set on the controller.