Traffic Lights Using Buttons/Switches etc..

Thread Starter

Ariel Arevalo

Joined Oct 16, 2019
Hi! I am new to electronics...

May I ask if I can use a simple integrated circuits (IC) like AND/OR/OR/XOR/NOR etc... to make a sequential traffic lights just by clicking buttons or switches?

For example... The circuit will start up with the GREEN LED light up.. then if I click a button, the GREEN and YELLOW will light up.. then i release the button... then if I clicked a button again, the RED will only light up... then i release the button again.. then I clicked a button again, only the GREEN will light up just from the start and repeat...

Note: Is it also possible if I only use a single button??

I appreciate your answers! Thank you!!


Joined Mar 10, 2018
Yes to single button could sequence an array of lights.

A shift register or counter, decoder and button debounce circuit could accomplish this.
And Red, Green, Yellow leds along with current limit R for each led.

Is this a school project, homework ?

Regards, Dana.


Joined Oct 2, 2009
You will need flip-flops and gates.
You can build flip-flops entirely from gates but that will make your project very complex.

This is a classic exercise in an introductory course in digital circuit design. You are attempting to build a finite-state machine, or a Mealy machine. You need to know about Karnaugh maps.

How much have you covered in your course so far?

Moderator edit: thread moved to Homework Help.