# 4 way traffic light system help

#### Grestei

Joined Nov 27, 2015
2
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.

#### Dodgydave

Joined Jun 22, 2012
10,359
Last edited:

#### absf

Joined Dec 29, 2010
1,968
What about like this?

#### Grestei

Joined Nov 27, 2015
2
Thanks all

#### aisah

Joined Feb 28, 2016
2
can i simulate the traffic lights in the multisim,,because our project must be done and perform using multisim app

#### aisah

Joined Feb 28, 2016
2
please help me! the dead line of our project is coming to an end

#### JoeJester

Joined Apr 26, 2005
4,390
can i simulate the traffic lights in the multisim,,because our project must be done and perform using multisim app
Yes.

#### WBahn

Joined Mar 31, 2012
26,412
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?