Traffic light LED circuit with IC CD4072

Traffic light control LED 6 LED, light (red, yellow and green) for both north-south and east / west directions.

The time sequence is generated using the CMOS 4017 decade counter and timer 555th Counter outputs 1 to 4 ares wire ORed with 4 LEDs, so the Red (- north / south) and (Green – East / West) LEDs will for the first four counts.

The fifth count (pin 10) illuminates (Yellow – East / West) and (Red – North / South).

Counts from 6 to 9 ares also wire or diodes control (Red – East / West) and (Green – North / South). Count 10 (pin 11) controls (Red – East / West) and (Yellow – North / South).

Deadline for red and green lights will be 4 times longer than the yellow and time to complete the cycle can be adjusted with the 47K resistor. 1N914 diodes eight could be subsituted with a dual 4 input or gate (CD4072).

LED traffic control circuit

Electrinic Part List

LM555              IC                  1pc.
CD4017             IC                 1pc.
2N3904             Transistor         4 pc
10K Ohms         Resistor          1pc.
47K Ohms          Resistor          1pc.
180 Ohms          Resistor          2pc.
Red                      LED               1pc.
Yellow              LED               1pc.
Green               LED               1pc.
1N914               Diode             8pc.
10uF/16V          Capacitor        1pc.
9V battery clips  Connector      1pc. (option)
PCB                                      1pc.

RLX resistor determines the brightness of the LED and current limiting for about 10 to 15mA when running between 9V to 12 VDC.
TRAFFIC flash scrolling speed is determined by the capacitors C1 and resistance R1 – C1 increases and reductions in R1, the slow speed.
For example, if the LM555 is set to generate one pulse per second, 1 Hz, the green light for 4 seconds to 1 yellow, red for 5