- The MQ-2 Gas Sensor
- How does it work?
- Pin Wiring
- Example: Gas Sensor with Arduino
- Video demonstration
This guide shows how to build a smoke detector that beeps when it detects flammable gas or smoke.
The MQ-2 Gas Sensor
The MQ-2 smoke sensor is the one in the following figure:
The MQ-2 smoke sensor is sensitive to smoke and to the following flammable gases:
The resistance of the sensor is different depending on the type of the gas.
The smoke sensor has a built-in potentiometer that allows you to adjust the sensor digital output (D0) threshold. This threshold sets the value above which the digital pin will output a HIGH signal.
How does it work?
The voltage that the sensor outputs changes accordingly to the smoke/gas level that exists in the atmosphere. The sensor outputs a voltage that is proportional to the concentration of smoke/gas.
In other words, the relationship between voltage and gas concentration is the following:
- The greater the gas concentration, the greater the output voltage
- The lower the gas concentration, the lower the output voltage
The output can be an analog signal (A0) that can be read with an analog input of the Arduino or a digital output (D0) that can be read with a digital input of the Arduino.
The MQ-2 sensor has 4 pins.
|Pin||Wiring to Arduino Uno|
Example: Gas Sensor with Arduino
In this example, you will read the sensor analog output voltage and when the smoke reaches a certain level, it will make sound a buzzer and a red LED will turn on.
When the output voltage is below that level, a green LED will be on.
So, for this example, you’ll need:
You can use the preceding links or go directly to MakerAdvisor.com/tools to find all the parts for your projects at the best price!
Follow these schematics to complete the project:
Upload the following sketch to your Arduino board (feel free to adjust the variable sensorThres with a different threshold value):
Watch this quick video demonstration to see this project in action:
I hope you found this guide useful.
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