MQ-3 Alcohol/Ethanol Gas Sensor Module 🍺

The MQ-3 Alcohol–Ethanol Sensor Module is a reliable, high-sensitivity gas sensor module designed to detect alcohol vapor in air. Ideal for breath alcohol analyzers, alcohol detection devices, and safety systems, it integrates easily with Arduino, Raspberry Pi (via external ADC), and other microcontroller-based projects. This module is a practical choice for both electronics engineers and hobbyists working with electronics components and sensor modules.

Key Features ✅

• High sensitivity to alcohol with minimal cross-sensitivity to benzine.
• Fast response and recovery for quick detection cycles.
• Stable operation with an extended service life.
• Simple drive circuit and straightforward interfacing.
• Affordable and compact for space-constrained designs.

Technical Specifications 📐

• Operating Voltage: 5 V
• Detection Range: 10 ppm – 1000 ppm Ethanol
• Heating Resistance (RH): 31 Ω ± 3 Ω
• Heating Current (IH): ≤ 180 mA
• Heating Voltage (VH): 5.0 V ± 0.2 V / 1.5 V ± 0.2 V
• Heating Power: ≤ 900 mW
• Response Time: ≤ 10 s (70% response)
• Recovery Time: ≤ 30 s (70% response)

Note: The heater can be driven per the datasheet either at 5 V DC or using a lower 1.5 V mode depending on the driving method. Follow recommended drive profiles for optimal accuracy and lifespan.

Pinout & Connections 🔌

• VCC: +5 V power input
• GND: Ground (power negative)
• DO: Digital TTL switch signal output (comparator with adjustable threshold)
• AO: Analog voltage output proportional to alcohol concentration

Typical Applications 🚀

• Breathalyzers: Measure alcohol concentration in exhaled breath.
• Alcohol detectors: Monitor alcohol levels in labs, manufacturing, or storage areas.
• Safety systems: Integrate into alarm or interlock systems to trigger alerts at set thresholds.

Integration Notes for Arduino, Raspberry Pi, and Microcontrollers 🛠️

• Power: Supply a stable 5 V. The heater may draw up to ~180 mA; ensure adequate current.
• Analog reading (AO): Connect to an ADC input. On Arduino, read via an analog pin (0–5 V). On Raspberry Pi, use an external ADC (e.g., MCP3008).
• Digital output (DO): TTL logic from onboard comparator; adjust the trip level with the module’s potentiometer.
• Warm-up: MQ-series sensors require heater warm-up for stable readings. Expect several minutes for regular use and a longer initial burn-in period (commonly 24–48 hours) for best accuracy.
• Calibration: Calibrate in clean air and known ethanol concentrations if possible. Temperature and humidity affect readings; consider compensation.

Best Practices & Safety ⚠️

• Use ventilation and avoid exposure to strong solvents or corrosive gases that may damage the sensor.
• Allow adequate preheat time before taking measurements.
• This module is intended for hobbyist and industrial monitoring; it is not certified for legal, medical, or law-enforcement use.