Light controlled automatic flashing lighting

The power circuit is composed of VD1, VD2, C2, C3 and R4. After the power is turned on,
about 12V DC working voltage can be obtained at both ends of the capacitor C2 to supply power to the light control circuit and oscillator. The light control circuit is composed of photoresistor RO and transistor
VT1. During the day, RG is exposed to natural light and has a low resistance. VTI is turned on, thus short-circuiting the base of transistor VT2 to
ground, so it is an ultra-low frequency oscillator composed of VT2 and VT3. Stop vibration. Both VT2 and VT3 are in the cut-off state, and the
diode VD3 is also in the cut-off state. The triac VS is also in the off-state because there is no trigger voltage, and the light H does not light up.
    At night, RG has a high resistance due to no light exposure, and VTI is cut off, thereby releasing the blockade of VT2.
The complementary ultra-low frequency oscillator composed of VT2 and VT3 will obtain the base bias current oscillation work through RP2 and RI, and .rr3 will be the gap. On and
off. When VT3 is turned on, its collector output forward trigger voltage is added to the control
electrode G of the thyristor vs through the diode VD3, triggering the thyristor vs to turn on, and the lamp H lights up. When VT3 is cut off, VD3 is also cut off. Because vs loses the
trigger voltage , it turns off when the alternating current crosses zero, and the light H goes out. So vs also opens and closes the gap, and the light H
flashes one after another. The potentiometer RP1 in the picture is used to adjust the light control sensitivity, so that the circuit can be triggered to work under the appropriate illumination .
Potentiometer RP2 is used to adjust the flashing frequency of lamp H. When the resistance of RP2 is small, the oscillation frequency is higher, and the flashing frequency of lamp H
is also accelerated. When the resistance of RP2 is large, the frequency is low. Lamp H flashes slower.