Ne555 light control street light circuit diagram

Circuit working principle : The circuit of this light-controlled automatic street light is composed of capacitors C1, C2 and diodes VD1~VD4, which form a capacitor step-down and bridge rectifier circuit. R1 and R2 are bleeder resistors. The zener diode VD5 stabilizes the rectified voltage of the previous stage within 12 V, which is used as the working voltage of the NE555 . C3 is the power supply filter capacitor, which can effectively suppress the ripple of the rectified voltage and obtain a smooth DC voltage. In the circuit, NE555 is connected as a bistable circuit. The photoresistor RC and the potentiometer RP form a simple voltage divider. The ② and ⑥ pins of NE555 are connected to the voltage dividing point. During the day, when the light is brighter, the photoresistor RG is in a low resistance state, so the voltage dividing point is at a high potential. When the voltage of pin ⑥ is above 2/3 of the power supply voltage, the bistable circuit is reset, the output pin ③ of NF555 is at low potential, the relay K does not work, and the street light L does not emit light. When night falls, the photoresistor RG shows high resistance due to lack of light exposure. At this time, the voltage dividing point is at a 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 a high potential. Following the circuit diagram of practical light-controlled switch street light automatic controller in Figure 1, electrical appliance K is powered to work. Its normally open contact K1 is closed, and the street lamp L is energized and emits light. Diode VD6 is connected in parallel at both ends of the relay coil to protect the integrated circuit from damage due to the self-induced electromotive force of the coil.

Component selection and debugging: The values ​​of diodes and resistor-capacitor components are marked according to the diagram. The trimmer potentiometer RP can change the potential of the voltage dividing point, so it can adjust the sensitivity of the light control, so that the street lamp can be powered on and glow when we need it to be lit. During specific debugging, you should first turn RP to the maximum resistance value, place the photoresistor RG in a dark place equivalent to night light, and use a cross screwdriver with good insulation performance to slowly fine-tune the small RP. When it reaches a certain position, it is estimated that the relay will K pulls in and the street light shines.

Remember: the power of the selected light bulb should not exceed 60 W. As long as the wiring is correct and the installation is complete. Interested readers and authors may wish to give it a try.