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MQ-3 Alcohol Gas Sensor

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Pin Description

For MQ-3 Sensor Module

Pin Name

Description

VCC

This pin powers the module, typically the operating voltage is +5V

GND

Used to connect the module to system ground

Digital Out (DO)

You can also use this sensor to get digital output from this pin, by setting a threshold value using the potentiometer

Analog Out (AO)

This pin outputs 0-5V analog voltage based on the intensity of the gas

For MQ-3 Sensor

1

H -Pins

Out of the two H pins, one pin is connected to supply and the other to ground

2

A-Pins

The A pins and B pins are interchangeable. These pins will be tied to Supply voltage.

3

B-Pins

A pins and B pins are interchangeable. One pin will act as output while the other will be pulled to ground.

 

Features of MQ-3 Alcohol Sensor

  • Sensor Type - Semiconductor
  • Easy SIP header interface
  • Compatible with most of the microcontrollers
  • Low-power standby mode
  • Requires heater voltage
  • Good sensitivity to alcohol gas
  • Fast response and High sensitivity  
  • Long life and low cost
  • Requires simple Drive circuit

Specifications of MQ-3 Gas Sensor

  • Power requirements: 5 VDC @ ~165 mA (heater on) / ~60 mA (heater off)
  • Current Consumption: 150mA
  • DO output: TTL digital 0 and 1 ( 0.1 and 5V)
  • AO output: 0.1- 0.3 V (relative to pollution), the maximum concentration of a voltage of about 4V
  • Detecting Concentration: 0.05-10mg/L Alcohol
  • Interface: 1 TTL compatible input (HSW), 1 TTL compatible output (ALR)
  • Heater consumption: less than 750mW
  • Operating temperature: 14 to 122 °F (-10 to 50°C)
  • Load resistance: 200kΩ
  • Sensitivity S: Rs(in air)/Rs(0.4mg/L Alcohol)≥5
  • Sensing Resistance Rs: 2KΩ-20KΩ(in 0.4mg/l alcohol)
  • Dimensions: 32 x 22 x 16 mm

Alternative MQ-3 Gas Sensors

Sensor Name

Gas to measure

MQ-2

Methane, Butane, LPG, Smoke

MQ-3

Alcohol, Ethanol, Smoke

MQ-4

Methane, CNG Gas

MQ-5

Natural gas, LPG

MQ-6

LPG, butane

MQ-7

Carbon Monoxide

MQ-8

Hydrogen Gas

MQ-9

Carbon Monoxide, flammable gasses

MQ131

Ozone

MQ135

Air Quality

MQ136

Hydrogen Sulphide gas

MQ137

Ammonia

MQ138

Benzene, Toluene, Alcohol, Propane, Formaldehyde gas, Hydrogen

MQ214

Methane, Natural Gas

MQ216

Natural gas, Coal Gas

MQ303A

Alcohol, Ethanol, smoke

MQ306A

LPG, butane

MQ307A

Carbon Monoxide

MQ309A

Carbon Monoxide, flammable gas

 

MQ-3 Equivalent Sensors

MQ-2, MQ214 (detection of Methane), MQ303A

 

Brief Detail about MQ-3 Gas Sensor

MQ-3 module is suitable for detecting Alcohol, Benzine, CH4, Hexane, LPG, CO. Sensitive material of MQ-3 gas sensor is SnO2, which with lower conductivity in clean air. When the target alcohol gas exist, the sensor’s conductivity is more higher along with the gas concentration rising. MQ-3 gas sensor has high sensitity to Alcohol, and has good resistance to disturb of gasoline, smoke and vapor.

This sensor provides an analog resistive output based on alcohol concentration. When the alcohol gas exist, the sensor’s conductivity gets higher along with the gas concentration rising.

There is a resistance across an A and  B inside the sensor which varies on detection of alcohol. More the alcohol, the lower the resistance. The alcohol is measured by measuring this resistance. The sensor and load resistor form a voltage divider, and the lower the sensor resistance, the higher the voltage reading will be.

Internal Structure of MQ-3 Sensor

Structure and configuration of MQ-3 gas sensor is shown in the figure above for Configuration A or B, sensor composed by micro AL2O3 ceramic tube, Tin Dioxide (SnO2) sensitive layer, measuring electrode and heater are fixed into a crust made by plastic and stainless steel net. The heater provides necessary work conditions for work of sensitive components. The enveloped MQ-3 have 6 pin, 4 of them are used to fetch signals, and other 2 are used for providing heating current.

 

Applications of MQ-3 Gas Sensor

  • Gas level over-limit alarm
  • Breathalyser
  • Portable alcohol detector
  • Stand-alone/background sensing device
  • Environmental monitoring equipment

 

2D Model of MQ-3 Sensor (Configuration A and B)

2D Representation of MQ3 Sensor

Component Datasheet

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