The control part consists of ICl555 integrated time base circuit, photoresistors RL, R2, W 1, W2, C4, C5, etc. According to the working principle of 555 integrated time base circuit. When RL is irradiated by strong light in the daytime, the resistance is low, and the potentials of feet ② and ⑥ of ICl rise. At this time, if V6≥V5, V2 >；; 1/2V5IC 13 pin output is low level IC2, VTl has no working voltage, LED2 is off, and optocoupler SCR IC3 cannot be turned on. CJ 1 line package has no pull-in current, the contact is in the off state, the external circuit does not work, and the lamp does not light up. As night falls, the light on RL is getting weaker and weaker, and the RL impedance is also increasing. When the five-pin voltage of V6lCl determines the trigger potential V7 and threshold potential V6 of 555 and satisfies the following relationship: V5=V6=2V2. Usually, under the condition of sufficient light, adjust W 1(W3) to make v2 >: Set "O" when 1/2V6o4 is "0" terminal < 0.7V, and connect the power supply when not in use. Pin 5 is added with a potentiometer W2. The threshold level V6 and the trigger level V2 can be changed. The function of VD5 is to cut off the power supply path from the battery to IC4 in case of power failure, so as to reduce the battery loss and prolong the working time of IC2.