Arduino LED Traffic Light Simulator
By Amit1379Components & Materials
Buy parts from the links below, then upload component photos in the content manager when you have product images.
- Add component photoArduino Uno (or Nano) — 1
- Add component photoRed, yellow, and green LEDs (5 mm) — 1
- Add component photo220 Ω resistors — 3
- Add component photoBreadboard and jumper wires — 1
- Add component photoUSB cable for Arduino — 1
This classic beginner project teaches you how to control digital output pins on an Arduino, create timed sequences, and understand basic circuit wiring. The finished traffic light cycles through red, amber, and green just like a real road signal.
Add photo: Finished project — Arduino LED Traffic Light Simulator
Before You Start
- Read through every step once before you begin.
- Confirm you have every component — use the Amazon, Temu, and AliExpress links in the parts list.
- Allow approximately 1.5 hours for this beginner build.
- Upload project and step photos in the content manager when ready (placeholders are marked below).
Step-by-Step Instructions
Follow each step in order. Replace the photo placeholders with your own images in WordPress when you publish.
Step 1: Wire the LEDs
Add photo: Wire the LEDs — Arduino LED Traffic Light Simulator
Insert the three LEDs into the breadboard with at least one row gap between each. Connect the long leg (anode) of each LED through a 220 Ω resistor to Arduino pins 11 (red), 10 (yellow), and 9 (green). Connect all short legs (cathodes) to the GND rail.
- Lay out all components from the parts list before you start wiring or assembling.
- Double-check polarity, orientation, and connections before powering on.
- Keep your workspace well lit and take photos as you go for your project gallery.
Step 2: Connect GND
Add photo: Connect GND — Arduino LED Traffic Light Simulator
Run a wire from any Arduino GND pin to the breadboard’s ground rail.
- Double-check polarity, orientation, and connections before powering on.
- Keep your workspace well lit and take photos as you go for your project gallery.
Step 3: Write the sketch
Add photo: Write the sketch — Arduino LED Traffic Light Simulator
In the Arduino IDE, define three pin constants. In loop(), turn red ON for 3 s, then red + yellow ON for 1 s, then green ON for 3 s, then yellow ON for 1 s, then repeat.
- Double-check polarity, orientation, and connections before powering on.
- Keep your workspace well lit and take photos as you go for your project gallery.
Step 4: Upload and test
Add photo: Upload and test — Arduino LED Traffic Light Simulator
Connect the Arduino via USB, select your board and port, and click Upload. The LEDs should begin cycling immediately.
- Double-check polarity, orientation, and connections before powering on.
- Keep your workspace well lit and take photos as you go for your project gallery.
Step 5: Extend it
Add photo: Extend it — Arduino LED Traffic Light Simulator
Add a button to trigger a pedestrian-crossing phase — turn all vehicle lights red, flash green for pedestrians, then resume normal cycle.
- Double-check polarity, orientation, and connections before powering on.
- Keep your workspace well lit and take photos as you go for your project gallery.
- Run a final test and note anything you would improve on a second build.
Safety Notes
- Always use current-limiting resistors with LEDs — omitting them will burn out the LED and can damage the Arduino pin.
- Keep the Arduino unplugged from USB while rewiring the breadboard.
Tips & Troubleshooting
- If an LED doesn’t light, check it isn’t inserted backwards — the long leg is positive.
- Dim LEDs usually mean the resistor value is too high; swap to 100 Ω for brighter output.
- This project runs on 5 V from USB — no external power supply needed.
Video walkthrough: Add your YouTube link in the project YouTube URL field in the content manager. The video embeds automatically at the top of the live project page.