DFRobot Gravity Analog Alcohol Sensor MQ3 for Arduino

The module requires a stable 5V DC power supply. This voltage powers both the module's logic and the sensor's internal heater. Applying voltages outside this range may damage the sensor or provide incorrect readings.

Connect the module's VCC to Arduino 5V, GND to GND, and the analog signal pin to an analog input (e.g., A0). The sensor outputs an analog voltage (0-5V) proportional to gas concentration. Use the `analogRead()` function in your Arduino sketch to obtain a value between 0 and 1023.

Yes, for accurate quantitative measurements, calibration is necessary. The sensor needs a pre-heating period of at least 24 hours for initial stabilization. After that, you should take a reading in clean air as a baseline (R0), and then expose it to a known concentration of alcohol to establish a response curve.

The MQ3 is primarily sensitive to alcohol (ethanol) vapor. It also shows some cross-sensitivity to other combustible gases like LPG, propane, and hydrogen, but its sensitivity is highest for alcohol. For specific alcohol detection, software filtering and proper calibration are required to minimize interference.

The blue potentiometer adjusts the threshold for the digital output pin (if your module version has one) or can be used to fine-tune the sensitivity of the analog reading circuit. Turning it clockwise generally increases sensitivity, making the sensor trigger at lower gas concentrations.