Night Light Saver Circuit Using AT89C2051

The Saver V5.0 runs simple clock emulation program, turns a night light on and off with preset time, say 19:00 to 22:00 everyday. The design features low cost, easy installation, no battery backup and no EMI. The AT89C2051 uses external oscillator generated by Schmitt trigger gate CD4093, ~680kHz. Reference frequency was derived from 50Hz main line. Time setting only allows at 18:00 by pressing time set button once. If main line has failed, functioning LED will blink at high rate . Since there is no battery backup, thus repressing the button is then needed. The output is capable of driving say, a 25W incandescent lamp.
Circuit Diagram