I did an interesting project to build a Traffic Light System using discrete components. That is transistors, resistors and capacitors only. No IC or a Micro-controller have been used in this project.
Ideally one would built this kind of system based on a Micro-Controller like Arduino. But I did this project as more of a challenge and as learning path to understand Analog Circuits
For more details checkout the video at
If you wish to learn more about its theory and working, continue to read further.