Ks0045 keyestudio MQ-7 Carbon Monoxide Gas Sensor

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Introduction

The gas sensitive material used in MQ-7 gas sensor is SnO2, which is of lower electrical conductivity in clean air.
It detects carbon monoxide with low temperature (heated by 1.5V) through high-low temperature cycles.
The electrical conductivity of the sensor increases with the increase of the carbon monoxide concentration in the air. The change of electrical conductivity can be converted to the output signal corresponding to that of the gas concentration by using a simple circuit.
The sensitivity of MQ-7 gas sensor to carbon monoxide is quite high, so it can be used to detect various gas containing carbon monoxide. It is a low-cost sensor suitable for a variety of applications.
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Specification

  • Target Gas: carbon monoxide
  • Detectable Concentration: 300-10000ppm CO
  • Loop Voltage Vc: ≤10V DC
  • Heating Voltage VH: 5.0V±0.2V ACorDC(hight); 1.5V±0.1V ACorDC(low)
  • Load Resistance RL: adjustable
  • Heating Resistance RH: 31Ω±3Ω(Room temperature)
  • Heating Power PH: ≤350mW
  • Surface Resistance of Sensitive Material R: 2KΩ-20KΩ(in100ppmCO)
  • Sensitivity S: Rs(in air)/Rs(100ppmCO)≥5
  • Concentration Slope: α ≤0.6(R300ppm/R100ppm CO)
  • Temperature, Humidity: 20℃±2℃ ; 65%±5%RH
  • Standard Test Circuit: Vc:5.0V±0.1V; VH(high): 5.0V±0.1V; VH(low): 1.5V±0.1V


Features

  • good sensitivity to carbon monoxide.
  • long service life, low cost
  • simple drive circuit


PINOUTS


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Connection Diagram


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Sample Code

///Arduino Sample Code
void setup()
{
  Serial.begin(9600); //Set serial baud rate to 9600 bps
}
void loop()
{
int val;

val=analogRead(0);//Read Gas value from analog 0
Serial.println(val,DEC);//Print the value to serial port
delay(100);
}


Test Phenomenon

When the sensor detects the carbon monoxide gas, its built-in led will light up as below figure shown.

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Application

  • household gas leak alarm
  • Industrial-level carbon monoxide gas alarm
  • Portable gas detector


Resources

  • Video

http://video.keyestudio.com/ks0040/

  • PDF and Code

https://drive.google.com/open?id=1EJNPTls2XZRfDJP01MiUD0aezh9-cH8A



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