Traffic traffic light control circuit

(1) Circuit composition
  1) The power circuit consists of the rectifier diode VD1, the current limiting resistor Ri, the voltage stabilizing diode vs and the filter capacitor cJ.
  2) The multivibrator circuit
is composed of potentiometer RP, resistor winder, winder, capacitor C2 and NOT gates D1~D3 inside the NOT gate integrated circuit IC2 (D1-D6).
    3) The counting distributor circuit consists of the counting/pulse distributor integrated circuit 1C1, diodes VD2~VD8 and resistors R2~R4.
    4) The lighting control circuit
is composed of NOT gates D4~D6, resistors Rr~Rlz, capacitors C4-C6, thyristors VTH1-VTH3 and indicator lights HU~HL3 inside IC2 .
    5) After the AC 220V voltage is rectified by VD1, Ri current limiting step-down, vs voltage stabilizing and Ci filtering, a 10V DC voltage is generated and supplied to IC1
and IC2.
    (2) Working principle of the circuit The multivibrator oscillates after being powered on, providing counting pulses for the @ pin of IC1. After the counting pulse is processed by IC1 and divided by
frequency, each of its output terminals outputs high level , and the thyristors VTH1-VTH3 are turned on in turn through the NOT gates D4~D6, and
HL1-HL3 are lit in turn.
    1) Yellow light HI. 2 lights up: When the ③ pin (YO terminal) or ① pin (Y5 terminal) of lCl outputs a high level, the NOT gate D5 outputs a low level,
causing VTH2 to be triggered to conduct, and the yellow light HL2 lights up. At this time, the NOT gate D4 and D6 output high level, VTH1 and VTH3 are cut off, and the red light
HL1 and green light HL3 do not light up.
    2) The red light HL1 is on: When the ②, ④, ⑦ and ⑩ pins (Yl-Y4 terminals) of Icl output high level, the NOT gate D4 outputs
a low level , causing VTH1 to be triggered and turned on, VTH2 and VTH3 is cut off and the red light HL1 is on.
    3) The green light HL3 lights up: When the ⑤, ⑥, ⑨ and ⑩ pins (Y6-Y9 terminals) of IC1 output high level, the NOT gate D6 outputs a low level
, causing VTH3 to be triggered and turned on, green Lamp HL3 lights up.     Adjusting the resistance of RP can change the oscillation period of the multivibrator, and the adjustment range is 1-10.