Hello friends! Today we will build a traffic-signal demonstration with Arduino using red, yellow and green LEDs. We will connect the three indicators, define their sequence and write a program that changes states using elapsed time. The same idea can be explored on a breadboard or in a suitable Proteus Arduino simulation. This is an educational model of one signal head. It teaches output control and timed state transitions; it is not a controller for a public road or a complete intersection. Real installations require coordinated phases, fault handling and jurisdiction-specific timing that cannot be established by a three-LED sketch. The original tutorial used long delays and changed directly from green to red before showing yellow. In this revision, we will use a clearly defined red, gree ...