Arduino project · LEDs and lights · Medium
Traffic Light with Night Mode
In daylight the green light is on. At night the yellow light blinks, like on a quiet road.
What you will learn
- How a sensor can change the mode of a machine
- How to blink a light
- How to mix conditions and timing
How it works
When the light is above 30 percent the green LED stays on. When it is dark the green goes off and the yellow blinks every 0.4 seconds.
Try this next
- Run a full red, green, yellow cycle in the day.
- Add a pedestrian button.
- Use a relay for a real signal lamp.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino pin (change it here) | How to wire it |
|---|
Every wire, one by one
Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.
| # | Item | Qty | Search term | Buy / compare |
|---|
The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.
In the real world
Traffic lights at night
At night the light blinks yellow. By day it uses the normal sequence.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.
- Light sensor = day or night
- LEDs = the signal lights