4 way traffic light system help

Thread Starter


Joined Nov 27, 2015
I am trying to do a 4-way traffic light system using a 555-timer and a 4017 for a school assignment. The traffic lights are to work in the following way:

1. Traffic lights 1 and 2- green light, traffic lights 3 and 4 both red light.

2. Traffic lights 3 - green light on its own. Traffic lights 1, 2, and 4 will be on their red light.

3. Traffic light 4 and 1 - green light while traffic lights 2 & 3 are red.

I have already managed to make step 1 and 2 work, but can't figure out how to make the third. Attached is the layout of my circuit so far. I would appreciate any help. Thanks in advance.tl.jpg


Joined Mar 31, 2012
The project specifies four lights and two colors for each light, so that's eight things. Why do you have twelve LEDs?

You don't have any current limiting resistors for any of your LEDs.

You have LEDs that are not completely connected.

You have LEDs in parallel, which is not a good idea.

Your problem only describes three states, but your circuit is using many more than that.

Using the Q output of the 555 as part of the timing circuit is not a good idea, but you can get it to function.

Don't leave the control voltage pin on the 555 floating.

Your reset approach on the counter seems kluged.

You have counter outputs that are shorted.

You have one output that is not going through a diode while the others are. Why?