Another Monday comes. God, it’s just like yesterday is Friday. As you know, the Weekend Specials of Geeetech has ended the previous weekend. Don’t be so upset, new activities is coming soon. Now I’ll give you some spoiler, ok  that’s jocking. Here comes our favorite item, the sensors introduction:  Carbon Monoxide Sensor – MQ-7.  

  The MQ-7 can detect CO-gas concentrations anywhere from 20 to 2000ppm.This is a simple-to-use Carbon Monoxide (CO) sensor, suitable for sensing CO concentrations in the air.

  The drive circuit is very simple; all you need to do is power the heater coil with 5V, add a load resistance, and connect the output to an ADC.This sensor has a high sensitivity and fast response time.

  Structure and configuration, basic measuring circuit

  Structure and configuration of MQ-7 gas sensor is shown as below (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 below, 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.

  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 200ppm CO in air and use value of Load resistance that( RL) about 10 KΩ(5KΩ to 47 KΩ).

  These are all the introduction of MQ-7. Click here if you want. Remember Carbon Monoxide is poisonous gas and keep it away from the kids.