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MQ-3 Alcohol Gas Sensor

Sensor

Gas sensor with a tin dioxide (SnO₂) sensing layer that detects alcohol vapour in the air; used in breathalyser projects. Its heater makes it warm while it runs; for steady readings, preheat it for 24-48 hours before first use.

Specifications

Detected gas

Alcohol (ethanol) vapour

Detection range

0.04 - 4 mg/L alcohol

Supply voltage

5V DC

Heater power

≤ 750 mW

Preheating

24 - 48 hours (first use)

Output

Analog (AO) + digital (DO)

Pins

VCC, GND, DO, AO

Shop prices

• RobocomboIn stock72.00 ₺
• Robo90In stock91.66 ₺
• MotorobitIn stock95.95 ₺
• Modül ElektronikIn stock96.92 ₺
• KomponentciIn stock99.44 ₺
• SAMM MarketIn stock110.14 ₺
• HatfonIn stock110.24 ₺
• RobotistanIn stock111.22 ₺
• Direnc.netIn stock132.50 ₺
• RobotsepetiIn stock140.81 ₺
• RobotzadeIn stock150.00 ₺
• Robolink MarketIn stock187.50 ₺
• F1 DepoOut of stock87.00 ₺

Prices read from the shops' pages on 22 October 2026. Prices and stock may have changed since; check at the shop before you buy.

Projects with this part

• Alcohol Measurement with the MQ-3 SensorBeginner25 minA project that measures alcohol vapour in the air with an MQ-3 gas sensor and writes the analog value and the threshold state to the Serial Monitor every half second. The analog value (0-1023) rises as the alcohol concentration goes up; the Limit value shows whether the threshold set with the trimmer on the board has been crossed. No extra library needed. The sensor's heater gets warm while it runs; on first use, leave the sensor powered for a while (ideally 24 hours), and let it warm up for a few minutes before measuring. The code uses 115200 baud, so pick 115200 in the Serial Monitor too.Open project