Traffic lights
From uCtrl.net
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Information
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.
Light signals
In sequence:
- Red
- Red and yellow (short)
- Green
- Yellow (short)
Sequence restarts.
Images
 Johnson counter pulses |
Traffic lights |
Schematic drawing
