Light controlled lantern circuit

During the Spring Festival, big red lanterns add a lot of festive and auspicious atmosphere to the festival. However, most lanterns are turned on/
off manually, which is inconvenient to use. In fact, as long as electronics enthusiasts make a practical light-controlled automatic switch, the lantern can automatically light up when it gets dark and
automatically go out when it gets bright, fully realizing the automatic on/off function.
    The working principle is as follows: The circuit principle is shown in Figure 9-33. Rr, Rz, VDl. VD2, C. , has formed a 1ZV power supply to provide
power supply voltage for the whole machine. NE555 and peripheral components form a Schmitt trigger with delay. RG in the circuit is a photosensitive resistor, used to detect the brightness of the surrounding environment
. At dusk, the brightness of the surrounding environment gradually becomes darker, and the resistance of RG also increases. The potential of pins ② and ⑥ of 1C1 gradually decreases. When the potential
is lower than Vcc/3, pin ③ of IC1 outputs high level, bidirectional. The thyristor VTH is triggered to conduct, and the lamp in the lantern is powered and lit. In the
morning, the sky gradually becomes brighter, the resistance of RG gradually becomes smaller, and the potential of Ic1 ② and ⑥ pins gradually increases. When the potential is higher than 2V{:c/3, ③ pin outputs
low level tVTH and cuts off. The light in the lantern goes out. It is composed of NE555 and peripheral components. The hysteresis voltage of the Schmitt trigger reaches Vc/3,
so when the brightness is near the critical brightness, the flickering phenomenon of the lamp can be eliminated. At the same time, in order to avoid the sudden change in surrounding brightness when fireworks are set off on festival nights
and cause the lights to flicker on/off, a delay capacitor G is specially added to the circuit .