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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.
Feature
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good sensitivity to carbon monoxide.
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long service life, low cost
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simple drive circuit
Application
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household gas leak alarm
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Industrial-level carbon monoxide gas alarm
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Portable gas detector
Specification
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Target gas: carbon monoxide
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Detectable concentration: 300-10000ppm CO
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Loop voltage Vc ≤10V DC
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Heating voltage VH 5.0V±0.2V ACorDC(hight); 1.5V±0.1V ACorDC(low)
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Load resistance RL adjustable
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Heating resistance RH 31Ω±3Ω(Room temperature)
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Heating power PH ≤350mW
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Surface resistance of sensitive material Rs 2KΩ-20KΩ(in100ppmCO)
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Sensitivity S Rs(in air)/Rs(100ppmCO)≥5
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Concentration slope: α ≤0.6(R300ppm/R100ppm CO)
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Temperature, humidity: 20±2;65%±5%RH
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Standard test circuit: Vc:5.0V±0.1V;VH(high): 5.0V±0.1V;VH(low): 1.5V±0.1V
