Arduino project · LEDs and lights · Easy
SOS Signal Light
The light and buzzer send three short, three long and three short signals: SOS in Morse code.
What you will learn
- How Morse code uses long and short signals
- How repeated steps build a pattern
- How to use timing to make meaning
How it works
A short signal is 200 ms, a long signal is 600 ms, and each is followed by a 200 ms gap. The sequence is three shorts, three longs and three shorts, then a 1.5 second pause before it repeats.
Try this next
- Send your own name in Morse code.
- Add a button that starts the signal.
- Use a relay and a torch.
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
A lighthouse that calls for help
The light flashes the SOS signal for ships and the horn sounds.
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.
- LED = the lighthouse lamp
- Buzzer = the horn