I need a simple 12vdc circuit that can switch between two 12vdc relays. The idea being that the first pulse operates relay one and the next pulse switches on relay No 2 in its place. I want to use a time clock to control this operation whereby the first time the time clock switches on (for a minimum time of 15 minutes) the first relay would switch on and then automatically switch off after a predetermined time and the next time the time clock switched on the second relay would operate reversing the direction.