Target: C2H5OH
Model: MQ-3B
Detection range: 25-500ppm
Detection principle: semiconductor
Characteristics: High sensitivity to alcohol gas and can resistant to the interference of gasoline, smoke and vapour.
Size: φ17×9.4
Working conditions: Loop Voltage:≤24V
Heater Voltage:5±0.1V
Heater consumption:≤900mW

MQ-3B Manual download
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Sensitive material of MQ-3B gas sensor is SnO2, which with lower conductivity in clean air. When the target alcohol gas exist, the sensor’s conductivity gets higher along with the gas concentration rising. Users can convert the change of conductivity to correspond output signal of gas concentration through a simple circuit.
MQ-3B gas sensor has high sensitivity to alcohol gas and can resistant to the interference of gasoline, smoke and vapour. It is with low cost and suitable for various applications of detecting alcohol at different concentration.


It is widely used in domestic alcohol gas alarm, industrial alcohol gas alarm and portable alcohol detector.


It has good sensitivity to alcohol in wide range, and has advantages such as long lifespan, low cost and simple drive circuit &etc.


Model MQ-3B
Sensor Type Semiconductor
Standard Encapsulation Plastic cap
Target Gas Alcohol gas
Detection range 25~500ppm alcohol
Standard Circuit Conditions Loop Voltage Vc ≤24V DC
Heater Voltage VH 5.0V±0.1V AC or DC
Load resistance RL Adjustable
Sensor character under standard test conditions Heater Resistance RH 29Ω±3Ω (room tem.)
Heater consumption PH ≤900mW
Sensitivity S Ro(in air)/Rs(125ppm C2H5OH)≥5
Output Voltage Vs 2.5V~4.0V (in125ppm C2H5OH)
Concentration Slope α ≤0.6(R300ppm/R50ppmC2H5OH)
Standard test conditions Tem.  Humidity 20℃±2℃;55%±5%RH
Standard test circuit Vc:5.0V±0.1V  VH:5.0V±0.1V
Preheat time Over 48 hours
O2 concentration 21%VOL(no less than 18%VOL)
Lifetime 10 years

* The description and specifications might be changed without notice. Please contact us for the latest information before placing orders.

Technical Support:

Customized technical design and function, LOGO and package are available without extra charge (including molding fee) for mass volume.

The sensors don't have sleeping mode. It can be set in program if needed.

All Winsen products go through strict inspections and tests to make sure they are 100% qualified before shipping out.

The sensor has been fully tested (not calibrated) before leaving the factory. However, after transportation and storage, the environment conditions change, and the surface of the sensor absorbs moisture, mixed gas, pollution matters, etc. It is recommended that customers perform aging and calibration after sensors become stable according to the program and use occasions of the whole device.

15﹪-90﹪RH without condensation,greater or less than this range or long-term high temperature and high humidity will affect the life of the sensor.

Our sensors are certified with CE, 3C, ROHS, anti-explosion, fire prevention, and coal mining safety according to different applications. And we provide assistance for new certification.

Many factors can cause the sensor to fail such as broken wires in transportation, poisoning, falling off of the sensitive material, damage to the heating wire (device), etc. Please find specific cause in each category with Winsen’s aftersales.

Winsen provides professional consultation and service before and after sales. We will recommend the best fitting sensor for your demand. If you have any problem, don’t hesitate to email us to

Due to high volume of daily incoming emails and time zone difference, we may not be able to reply your emails immediately. But we will reply to your inquiry in 24 business hours.