How MQ2 Gas/Smoke Sensor Works with Arduino - Electronic and Telecommunication Engineering

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How MQ2 Gas/Smoke Sensor Works with Arduino

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What is MQ2 Gas Sensor?

      MQ2 is one of the typically used gas sensors in MQ sensor series. It is a Metal Oxide Semiconductor (MOS) type Gas Sensor also referred to as Chemiresistors as the detection is primarily based upon alternate of resistance of the sensing material whilst the Gas comes in contact with the fabric. Using a easy voltage divider network, concentrations of gas may be detected.

     MQ2 Gas sensor works on 5V DC and draws round 800mW. It can hit upon LPG, Smoke, Alcohol, Propane, Hydrogen, Methane and Carbon Monoxide concentrations everywhere from 200 to 10000ppm.






What is 1 ppm same to?

When measuring gases like carbon dioxide, oxygen, or methane, the term attention is used to explain the amount of gas via extent in the air. The 2 most not unusual gadgets of measurement are components-constant with-million, and percent consciousness.

Parts-regular with-million (abbreviated ppm) is the ratio of one fuel to every other. For instance, 1,000ppm of CO manner that if you can depend 1,000,000 gas molecules, 1,000 of them might be of carbon monoxide and 999,000 molecules might be some exclusive gases


Internal shape of MQ2 Gas Sensor

       The sensor is without a doubt enclosed in two layers of excellent stainless steel mesh referred to as Anti-explosion community. It guarantees that heater detail inside the sensor will now not motive an explosion, as we are sensing flammable gases.






It also presents safety for the sensor and filters out suspended debris simply so simplest gaseous elements are able to bypass within the chamber. The mesh is certain to rest of the frame thru a copper plated clamping ring.








This is how the sensor looks as if while outer mesh is removed. The famous person-fashioned structure is shaped via the sensing element and 6 connecting legs that increase beyond the Bakelite base. Out of six, two leads (H) are chargeable for heating the sensing element and are connected thru Nickel-Chromium coil, widely recognized conductive alloy.

The ultimate four leads (A & B) responsible for output signals are linked using Platinum Wires. These wires are related to the body of the sensing element and produce small modifications in the modern that passes via the sensing detail.







The tubular sensing detail is made from Aluminum Oxide (AL2O3) primarily based ceramic and has a coating of Tin Dioxide (SnO2). The Tin Dioxide is the most essential fabric being touchy closer to combustible gases. However, the ceramic substrate merely increases heating efficiency and ensures the sensor vicinity is heated to a running temperature continuously.







How does a gas sensor work?

When tin dioxide (semiconductor debris) is heated in air at excessive temperature, oxygen is adsorbed on the floor. In easy air, donor electrons in tin dioxide are attracted closer to oxygen that's adsorbed at the floor of the sensing fabric. This prevents electric powered current flow.

In the presence of lowering gases, the surface density of adsorbed oxygen decreases because it reacts with the reducing gases. Electrons are then released into the tin dioxide, permitting modern to go with the flow freely through the sensor.





Hardware MQ2 Gas Sensor Module

        Since MQ2 Gas Sensor isn't always breadboard well matched, we do propose this accessible little breakout board. It’s very clean to apply and comes with  one-of-a-kind outputs. It no longer simplest provides a binary indication of the presence of flamable gases however additionally an analog illustration in their attention in air.





The analog output voltage supplied by means of the sensor adjustments in proportional to the awareness of smoke/fuel. The extra the gas awareness, the better is the output voltage; even as lesser fuel concentration consequences in low output voltage. The following animation illustrates the relationship among gas attention and output voltage.







The analog signal from MQ2 Gas sensor is in addition fed to LM393 High Precision Comparator (soldered on the lowest of the module), of course to digitize the sign. Along with the comparator is a chunk potentiometer you could flip to modify the sensitivity of the sensor. You can use it to alter the awareness of gasoline at which the sensor detects it.

Calibrate MQ2 Gas Sensor Module

       To calibrate the gasoline sensor you could maintain the fuel sensor close to smoke/gas you need to find out and keep turning the potentiometer till the Red LED on the module starts offevolved offevolved offevolved sparkling. Turn the screw clockwise to boom sensitivity or anticlockwise to lower sensitivity.












        The comparator on the module continuously tests if the analog pin (A0) has hit the brink price set via potentiometer. When it crosses the threshold, the virtual pin (D0) will pass HIGH and sign LED activates. This setup might be very beneficial even as you want to purpose an movement while effective threshold is reached. For example, whilst the smoke crosses a threshold, you can prompt or off a relay or educate your robot to blow air/sprinkle water. You had been given the concept


MQ2 Gas Sensor Module Pinout

Now permit’s have a take a look at the pinout.







      VCC. Materials electricity for the module. You can connect it to 5V output out of your Arduino.
      
      GND. is the Ground Pin and desires to be related to GND pin at the Arduino.

      D0.offers a virtual example of the presence of flamable gases.

     A0. gives analog output voltage in proportional to the attention of smoke/gasoline.

 
Connecting MQ2 Gas Sensor Module to Arduino UNO

Connecting the MQ2 Gas sensor module to the Arduino is pretty smooth. Start by way of putting the sensor on to your breadboard. Connect VCC pin to the 5V pin at the Arduino and connect GND pin to the Ground pin on the Arduino.

Connect D0 output pin at the module to Digital pin#eight at the Arduino and A0 output pin on the module to Analog pin#0 on the Arduino.












Arduino Code



#define MQ2pin (zero)

glide sensorValue;  //variable to keep sensor cost

void setup()

  Serial.Start(9600); // sets the serial port to 9600
  Serial.Println("Gas sensor warming up!");
  put off(20000); // permit the MQ-6 to warm up


void loop()

  sensorValue = analogRead(MQ2pin); // read analog input pin zero
  
  Serial.Print("Sensor Value: ");
  Serial.Print(sensorValue);
  
  if(sensorValue > three hundred)
  
    Serial.Print(" 
  
  Serial.Println("");
  postpone(2000); // wait 2s for next analyzing



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