... you lost me there BrownOut, but i think that you're right about the relays. i'm just making rough guesses here, if te tracker can rotate a full 180º and it travels the full distance every day, then if the tracker travels...say...3º at a time, that would make 60 cycles on the relay per day. most relays i work with have an expected life of 10,000 cycles, but if treated properly and shown tender loving care, they can last for up to 1,000,000 cycles. problem is you're not giving it tender loving care, you're making the circuit and chaining it up out back for nature to do as it would. relays, bad idea. the problem with almost (if not all) electronic parts is their opperating temperature. i can only assume that this racker is going to be in decent opperating conditions. also you mentioned something about resetting the circuit at dawn, what about at dusk?
sle, to answer your question, it's the circuit in post #29