Traffic Light Controller circuit using CD4017 IC Datasheet

Traffic Light Controller circuit

The Traffic Light Controller circuit using CD4017IC  The circuit’s timing and sequential operation is done by two CMOS ICs (IC1 and IC2) while the actual power switching is done by Triacs.

CD4017 IC Circuit Diagram

Traffic Light Controller circuit using CD4017 IC

Traffic Light Controller circuit using CD4017 IC

From the Traffic Light Controller circuit using CD4017 IC, a 10V negative power supply is obtained directly from the mains by means of D1, R1, D2, and C1. Gates N1 through N6 constitute IC2 while IC1 is a Johnson counter. N1 – N3 is wired as an astable multivibrator whose time period can be adjusted between 1 second and 10 seconds with VR1. The decade outputs of IC1 are wired such that when Q0 and Q5 are high, the output of N5 goes low.

The outputs of N4 and N6 become low when Q1 to Q4 and Q6 to Q9 become low respectively. Since we have a negative supply, the low output of any of the hates N4 to N6 causes the respective Triac to fire.

Traffic Light Controller circuit


Resistors (all ¼-watt, ± 5% Carbon unless stated otherwise)
R1 = 5 KΩ/5W
R2, R3, R4 = 22 KΩ
R5 = 100 KΩ
R6 = 1 MΩ
R7, R8, R9 = 1 KΩ
R10, R11, R12 = 100 Ω/1W
VR1 = 1 MΩ
C1 = 1000 µF/16V
C2, C3 = 22 µF/16V
C4, C5, C6 = 00.1 µF/400V
IC1 = CD4017
IC2(N1 – N6) = CD4049
D1 = BY127



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