Circuit working principle: the circuit of this light controlled automatic street lamp is a capacitor step-down and bridge rectifier circuit composed of capacitors C1 and C2 and diodes VDL ~ VD4, and R1 and R2 are discharge resistors. The zener diode vd5 stabilizes the rectified voltage of the previous stage within 12V as the working voltage of NE555. C3 is the power filter capacitor, which can effectively suppress the ripple of the rectified voltage and obtain a smooth DC voltage. In the circuit, NE555 is connected into a bistable circuit, the photosensitive resistor RC and potentiometer RP constitute… A simple voltage divider, and the ② and ⑥ pins of NE555 are connected to the voltage dividing point. During the day, the light is bright, and the photosensitive resistance Rg is in a low resistance state. Therefore, the partial voltage point is a high potential. When the voltage of ⑥ pin is above 2 / 3 of the power supply voltage, the bistable circuit resets, the output terminal ③ pin of nf555 is low potential, the relay K does not work, and the street lamp L does not emit light. When night falls, the photoresist RG shows high resistance due to no light irradiation, and the partial voltage point is low potential. When the potential of pin ② of NE555 is below 1 / 3 of the power supply voltage, the bistable circuit is set, and pin ③ of NE555 outputs high potential. Following the circuit diagram of the practical light control switch street lamp automatic controller in Figure 1, the electric appliance K is powered on, its normally open contact K1 is pulled in, and the street lamp L is powered on and illuminated. The diode vd6 is connected in parallel at both ends of the relay coil, which can protect the integrated circuit from being damaged by the self induced electromotive force of the coil.
Component selection and commissioning: diodes and resistance capacitance components are taken according to the notes in the icon. The fine-tuning potentiometer RP can adjust the sensitivity of the light control because it can change the potential of the voltage dividing point, so that the street lamp can be powered on when we need to light up. During specific commissioning, first rotate RP to the maximum resistance value, place the photosensitive resistance Rg at the dark light equivalent to the night, and slowly and carefully adjust RP with a cross screwdriver with good insulation performance. When it is estimated to a certain position, relay K is pulled in and the street lamp is illuminated.
Remember: the power of the selected bulb shall not exceed 60 W. As long as the wiring is correct… Install it. Interested readers and authors might as well give it a try.