Photoelectric control lighting circuit using photosensitive sensor

Photoelectric control lighting circuit using photosensitive sensor

Shown is a photoelectrically controlled lighting circuit using a photosensitive sensor (photoresistor) .
    This circuit is suitable for street lights, door lights, corridor lighting and other occasions. During the day, the bulb in the circuit does not light up; when the light is weak,
the bulb can light up automatically.
    When the light is strong during the day, the resistance value of the photoresistor RG is small, then the input terminal of ICI is low level and the output terminal is high level. At this time,
VDI is turned on, and the ② and @ pins of IC2 are high level, ③ The pin outputs a low level, and the light-emitting diode VD2 lights up, but the relay coil KA does not close and
the bulb L does not light up.
    When the light is weak. The resistance value of k becomes larger. At this time, the voltage at the input terminal of IC1 becomes high level and the output is low level, causing VD1 to cut off.
At this time , the capacitor cl begins to charge under the action of the external DC power supply, causing the potential of IC2② and ⑥ pins to gradually increase. reduce. @ pin outputs a high level, causing
the relay coil KA to close, driving the normally open contact to close, and the light bulb L is powered on and lit.