Light control street light circuit

The installation of street lights generally adopts the method of concealed wiring through trench pipes. The control part is installed at the gate or controlled uniformly in the duty room of the electrician room.
The street lights in a certain factory area are shown in Figure a. In addition to convenient transportation, it is also a place for people to relax, walk, play and exercise on both sides of the road
. The working principle of the light-controlled street light circuit: The light-controlled street light is characterized by stable and reliable operation, and will not cause malfunction or flicker
    due to accidental strong light exposure .     The light-controlled street light circuit consists of a light-controlled trigger circuit, a switch circuit and a power supply circuit, as shown in Figure 16-45b. In the light-controlled street light circuit, the light-controlled trigger circuit consists of a photoresistor RG . It is composed of potentiometer RP, capacitor C3, 0, resistor R3 and time base integrated circuit NE555; the switching circuit is composed of thyristor VTH, resistor R2 and light-emitting diode LED; the power circuit is composed of step-down capacitor Ci, resistor R, and voltage stabilizing circuit It is composed of diode vS, rectifier diode VD and filter capacitor G. After the AC 220V voltage is stepped down by Cl, stabilized by vs, rectified by VD and filtered by C2, a DC voltage of 8. SV (V0) is generated and supplied to NE555.     During the day, the photoresistor RG is in a low-resistance state when exposed to light. The potential of pins ② and ⑥ of NE555 is higher than 2V.T/3, pin ③ of NE555 outputs low level, the light-emitting diode LED does not emit light, and the thyristor VTH is cut off. status, the lighting EL is not on.     When night falls, the illumination gradually weakens and the resistance of the photoresistor RG gradually increases. The voltage of pin ② and pin ⑤ of NE555 also begins to drop. When the voltage of the two pins drops to V"/3, the internal trigger of NE555 flips. Pin ③ changes from low level to high level, causing the LED to turn on and emit light . VTH is triggered and turned on, turning on the lighting lamp EL.