MQ3 Gas Sensor example

The MQ3 Gas Sensor module is useful for gas leakage detection (in home and industry). It is suitable for detecting Alcohol, Benzine, CH4, Hexane, LPG, CO. Due to its high sensitivity and fast response time, measurements can be taken as soon as possible.

The sensitivity can be adjusted by using the potentiometer on the module.

MQ-3
MQ-3

Specification

Item Parameter Min Typical Max Unit
VCC Working Voltage 4.9 5 5.1 V
PH Heating consumption 0.5 750 mW
RL Load resistance adjustable
RH Heater resistance 33 Ω
Rs Sensing Resistance 1 8
Scope Detecting Concentration 0.05 10 mg/L

Parts List

I recommend you try and get a kit of all the MQ sensors, you can buy these individually but you can also get a kit for about $9

Here are the parts I used

Name Links
Wemos Mini
MQ sensors
Connecting cables

 

Connection

My sensor was wired up as follows

Wemos Gas Sensor
3.3V VCC
GND GND
NC D0
Analog A0 A0

 

Code

 

void setup() 
{
  Serial.begin(9600);
}
 
void loop() 
{
  float sensorVoltage; 
  float sensorValue;
 
  sensorValue = analogRead(A0);
  sensorVoltage = sensorValue/1024*5.0;
 
  Serial.print("sensor voltage = ");
  Serial.print(sensorVoltage);
  Serial.println(" V");
  delay(1000);
}

 

Results

I saw the following results in the serial monitor

sensor voltage = 1.83 V
sensor voltage = 1.78 V
sensor voltage = 1.74 V
sensor voltage = 1.70 V
sensor voltage = 1.66 V
sensor voltage = 1.63 V
sensor voltage = 1.59 V
sensor voltage = 1.56 V

 

Links

Mq-3 Gas sensor specs

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