Circular light control circuit

Shown is a cyclic light control circuit. In the circuit, rCl is a two-input terminal four -NAND gate CD4011, in which
a multivibrator is composed of NAND gates 1 and 2, and an RS trigger circuit is composed of NAND gates 3 and 4 to process the pulses generated by the multivibrator. Shaping, and then outputs the clock pulse
from the output terminal of NAND gate
4 to the Cp terminal of IC2.     IC2 is a decimal counting/frequency divider CD4017. When its Cp terminal inputs a clock pulse, high-
level pulse signals will appear sequentially at the output terminals Qo-Q3. When Qo-Q3 appear high level in sequence, the solid-state relays Kl~K4 are triggered and turned on in sequence, so that the corresponding lamps H1~
H4 are lit one by one. After clearing IC2, the above process starts again, thus realizing the function of controlling the light cycle.
    in the circuit. The sequential lighting time of each street lamp and the time for all lights to be turned off are the same. Adjusting RP1 can make the time
change between 0.1-10 s.