Gas Leakage Detector Project Explanation (No Soldering!)
by ElectroScope Archive in Circuits > Arduino
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Gas Leakage Detector Project Explanation (No Soldering!)

In this project, we will build a really simple Gas Leak Detector using an Arduino Uno and an MQ-5 gas sensor. The build is designed to detect gases like LPG, propane, and methane. In simple terms, we build something with a sensor that sounds off a buzzer and lights an LED when a gas leak is detected. This is a great way to explore concepts around sensor and safety automation with Arduino.
Supplies
- Arduino Uno ×1
- MQ-5 Gas Sensor Module ×1
- Buzzer ×1
- LED ×1
- 220Ω Resistor ×1
- 10kΩ Resistor ×1 (optional – for reducing buzzer volume)
- Breadboard ×1
- Jumper Wires (as needed)
- USB Cable or 9V Battery (for power)
Circuit Diagram & Wiring

This is how to connect all the pieces together:
MQ-5 Gas Sensor:
- VCC → 5V (Arduino)
- GND → GND (Arduino)
- D0 (Digital Out) → A2 (Arduino)
Buzzer:
- Positive terminal → A0 (Arduino)
- Negative terminal → GND (You can use a 10kΩ resistor in series to decrease volume if necessary)
LED:
- Anode (+) → A1 (Arduino) using 220Ω Resistor
- Cathode (-) → GND
Power Options:
- USB cable to Arduino
- 9V battery to Arduino Vin and GND
Upload the Code
Open Arduino IDE and upload the following code:
Downloads
Tuning the Gas Sensor
To make the sensor work accurately, you will need to adjust the onboard potentiometer:
- In clear air, turn the potentiometer clockwise until the onboard LED for the sensor is OFF.
- Bring a gas source (unlit lighter) close to the sensor - this should trigger the LED.
- Adjust clockwise for decreased sensitivity or counterclockwise for increased sensitivity.
Sensor warm-up time: Let it run for at least 24 hours.
Demo in Action

When powered and tuned properly:
- If gas is present, the LED turns ON, the buzzer sounds, and "Gas Leak Detected" is printed on the Serial Monitor.
- If no gas is present, the system stays silent and prints "Environment Normal."
Conclusion
And that's it. You’ve just built a fully functional DIY gas leak detector.
If you'd like a more comprehensive tutorial, here it is: DIY Gas Leak Detector Using Arduino
If you're curious about how this project compares to a commercial unit in tech commentary style: DIY vs Commercial Gas Leak Detector — Which One ‘Blows’?
To expand on this project, feel free to add IoT features for alerts or connect it to a home automation system using relays. You could experiment with different gas sensors or add an LCD for local readings.