How do I set the transformer to turn lights on at dusk and off at dawn automatically?

Press MENU until the PHOTOCELL AUTO ON/OFF LED indicator is lit, then press OK to activate this mode. The digit display will show the current time and the AM/PM LED indicator will stay lit. The start delay time is 0.1 sec. ± 1 sec. and the off delay time is 60 sec. ± 10 sec. (Page 8)