基于51单片机，当光敏数值小于20时，继电器1和2工作，当数值小于10时继电器3延时5秒工作，当数值大于50时继电器全部断开。（数值参数和延时数值可更改，继电器可加减）(Based on 51 single-chip microcomputer, when the light sensitive value is less than 20, the relay 1 and 2 work, when the value is less than 10, the relay 3 delay 5 se