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Traffic lights with a 555 timer
Simple traffic lights controller circuit with 555 timer and 4017 counter.
The circuit consists of a 555 timer and a 4017 Johnson counter. The 555 timer sends pulses (0.47 Hz) to the Johnson counter, which changes output. By connecting some outputs together the timing of the light signals can be controlled. Four steps are used for the green LED and two for the yellow. The red LED is connected to pin 12 which is active for the first five steps. The white LED shows the pulses from the 555 timer.
- Red and yellow (short)
- Yellow (short)
|1 ×||Capacitor, aluminium electrolytic, 47 µF, 25V|
|1 ×||Capacitor, metallized polyester foil, 6.8 nF, 63V|
|1 ×||Capacitor, metallized polyester foil, 10 nF, (0.01 µF)|
|6 ×||Diode, small signal, 1N4148/Ph|
|1 ×||Johnson decade counter, 5-stage, 4017, DIL-16|
|1 ×||LED 5mm, Green, 2.0V, 10mA|
|1 ×||LED 5mm, Red, 2.0V, 20mA|
|1 ×||LED 5mm, Red/Green, 2.0 2.1V, 10mA, 100 63mcd, 30°|
|1 ×||LED 5mm, Yellow, 2.0V, 25mA|
|32 cm2||PCB, stripboard, 100x160mm, 160cm2|
|1 ×||Resistor, carbon film, 0.25W, 10 kΩ, 5%|
|2 ×||Resistor, carbon film, 0.25W, 22 kΩ, 5%|
|1 ×||Resistor, carbon film, 0.25W, 100 kΩ, 5%|
|4 ×||Resistor, metal film, 0.6W, 1 kΩ, 1%|
|2 ×||Straight pin header, male, Single row, 2.54mm|
|1 ×||Timer IC, NE 555, 0/+70 °C, DIL8|