This activity operates red, amber and blooming LEDs in the actual arrangement for a distinct UK cartage light. The time taken for the complete red - red & amber - blooming - amber arrangement can be assorted from about 7s to about 2½ account by adjusting the 1M preset. Some amber LEDs afford ablaze that is about red so you may adopt to use a chicken LED.
How to build Traffic Light
The 555 astable ambit provides alarm pulses for the 4017 adverse which has ten outputs (Q0 to Q9). Each achievement becomes aerial in about-face as the alarm pulses are received. Appropriate outputs are accumulated with diodes to accumulation the amber and blooming LEDs. The red LED is affiliated to the ÷10 achievement which is aerial for the aboriginal 5 counts (Q0-Q4 high), this saves application 5 diodes for red and simplifies the circuit.
This activity uses a 555 astable ambit to accommodate the alarm pulses for the 4017 counter.
Parts Required
resistors: 470 ×3, 22k, 100k
capacitors: 0.1µF, 1µF 16V radial, 10µF 16V radial
diodes: 1N4148 ×6
LEDs: red, amber (or yellow), green
1M preset, horizontal
555 timer IC, such as NE555
4017 adverse IC
DIL sockets for ICs: 8-pin, 16-pin
on/off switch
battery blow for 9V PP3
stripboard: 20 rows × 21 holes