A two-way traffic light using a CMOS 4017 and 555. To be used as toy only. (4/23/2006)
I built this traffic light when I was a kid. This first one that I built was one-way only, later, when I found how to use transistors I was able to create a two-way one.
Here is the schematic:
Althoug this circuit can work with voltages up to 15V, is better to use it with four AAA batteries. The 555 creates a square wave oscillator, the frecuency is changed by the 100k variable resistor.
The Cmos 4017 count from cero to nine, while counting from cero to four, it controls one way. The other way is controlled while counting from five to nine.
With a flip-flop, is possible to connect two of this circuits and create a four-way traffict light.
This circuit was originally devised on March 1991.
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