Wrobot Mini Mq7 High Sensitivity Gas Sensor

Specification:
1, High sensitivity to Combustible gas in wide range.
2, Can detect CO gas.
3, Adjustable Sensitivity, Stable Performance.
4, 5V Working Voltage, support both the output digital value and the output analog value.
5, Port explanation: DO for digital output, AO for analog output.
6, Applicable to a variety of platforms including Arduino / AVR / ARM.

D. Structure and configuration, basic measuring circuit
Structure and configuration of MQ*7 gas sensor is shown as Fig. 1 (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*7 have 6 pin, 4 of them are used to fetch signals, and other 2 are used for providing heating current.

Standard circuit:
As shown in Fig 2, standard measuring circuit of MQ*7 sensitive components consists of 2 parts. One Is heating circuit having time control function (the High voltage and the low voltage work Circularly ). The second is the signal output circuit, It can accurately respond changes of surface Resistance of the sensor.

SENSITVITY ADJUSTMENT
Resistance value of MQ*7 is difference to various kinds and various concentration gases. So, When Using this components, sensitivity adjustment is very necessary. We recommend that you calibrate the Detector for **0ppm CO in air and use value of Load resistance that( RL) about *0 KΩ (5KΩ To *7 KΩ ).
When accurately measuring, the proper alarm point for the gas detector should be determined after Considering the temperature and humidity influence.

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