====== LamaPLC: MQ Winsen Gas-sensors ======

Winsen's MQ series gas sensors are low-cost, semiconductor-type (chemiresistive) sensors designed to detect a wide range of gases, including flammable gases, alcohol, and smoke. Each model is tailored to detect specific gases or a range of gases.

  * **Operating Principle:** The sensors use a sensitive material (typically SnO2 semiconductor) and a heating element. The sensor's conductivity varies with air-gas concentration, enabling measurement using a simple voltage divider.
  * **Voltage:** They operate on a standard 5-volt DC power supply.
  * **Low Cost:** A major advantage is their affordability, making them popular for a wide variety of civil and industrial applications, including smart homes and IoT projects.
  * **"Burn-in" Time:** A //"burn-in"// period of 12 to 24 hours is often recommended to improve measurement accuracy.

|{{anchor:mq2}}{{:sensor:g.png|Gas sensor}}\\ <color blue>smoke \\ LPG (liquefied petroleum gas) \\ propane \\ hydrogen</color>|Winsen \\ **MQ-2** {{ :sensor:mq_2.png?100 |MQ-2}}|Flammable gas concentracion: 300 .. 10'000ppm \\ \\ Heater Resistance; RH: 29Ω ±3Ω（room tem.）\\ Heater consumption; PH: ≤950mW \\ Sensitivity;S: Ro(in air) / Rs (2000 ppm C<sub>3</sub>H<sub>8</sub>) ≥ 5 \\ Output Voltage;Vs: 2.5V～4.0V（in 2000 ppm C<sub>3</sub>H<sub>8</sub>）\\ Concentration Slope;α: ≤0.6 (R3000 ppm / R1000 ppm C₃H₈)|
|{{anchor:mq3}}{{:sensor:g.png|Gas sensor}}\\ <color blue> alcohol (C₂H₅OH) </color> \\ \\ <color orange> Small sensitivy:</color> \\ <color blue> Benzine gas </color>|Winsen \\ **MQ-3** {{ :sensor:mq_3.png?100 |MQ-3}}|Detecting concentration scope：0.05 mg / 10 mg/L Alcohol \\ \\ Sensing Resistance: 1 MΩ - 8 MΩ (0.4 mg/L alcohol)|
|{{anchor:mq4}}{{:sensor:g.png|Gas sensor}}\\ <color blue>Methane CH₄ \\ Natural gas \\ LNG </color> \\ \\ <color orange>Small sensitivy:</color><color blue> \\ Alcohol \\ Smoke</color>|Winsen \\ **MQ-4** {{ :sensor:mq_4.png?100 |MQ-4}}|Detecting concentration scope：200-10'000ppm CH₄, natural gas \\ \\ Sensing Resistance: 10KΩ- 60KΩ (1000ppm CH<sub>4</sub>)|
|{{anchor:mq5}}{{:sensor:g.png|Gas sensor}}\\ <color blue>LPG \\ Iso-butane \\ Propane </color> \\ \\ <color orange>Small sensitivy:</color><color blue> \\ Alcohol \\ Smoke</color>|Winsen \\ **MQ-5** {{ :sensor:mq_5.png?100 |MQ-5}}|Detecting concentration scope: 200-10,000ppm LPG, LNG, Natural gas, Iso-butane, Propane, Town gas \\ \\ Sensing Resistance: 10KΩ- 60KΩ (5000 ppm methane)|
|{{anchor:mq6}}{{:sensor:g.png|Gas sensor}}\\ <color blue>Town gas \\ Natural gas \\ LPG \\ LNG \\ Iso-butane \\ Propane</color> \\ \\ <color orange>Small sensitivy:</color><color blue> \\ Alcohol \\ Smoke</color>|Winsen \\ **MQ-6** {{ :sensor:mq_6.png?100 |MQ-6}}|Detecting concentration scope：200-10'000ppm LPG ,iso-butane, propane, LNG \\ \\ Sensing Resistance: 10KΩ- 60KΩ (10'00ppm LPG)|
|{{anchor:mq7}}{{:sensor:g.png|Gas sensor}}\\ <color blue>CO</color>|Winsen \\ **MQ-7** {{ :sensor:mq_7.png?100 |MQ-7}}|Detecting concentration scope： over 300 ppm CO (Carbon Monoxide)\\ \\ Sensing Resistance: 2KΩ- 20KΩ (100 ppm CO)|
|{{anchor:mq8}}{{:sensor:g.png|Gas sensor}}\\ <color blue>H<sub>2</sub></color> \\ \\ <color orange>Small sensitivy:</color><color blue> \\ Alcohol \\ LPG \\ cooking fumes</color>|Winsen \\ **MQ-8** {{ :sensor:mq_8.png?100 |MQ-8}}|Detecting concentration scope：100-10000ppm Hydrogen (H₂)\\ \\ Sensing Resistance: 10KΩ- 60KΩ (1000 ppm H<sub>2</sub>)|
|{{anchor:mq9}}{{:sensor:g.png|Gas sensor}}\\ <color blue>CO \\ Methane CH₄ \\ LPG </color> |Winsen \\ **MQ-9** {{ :sensor:mq_9.png?100 |MQ-9}}|Detecting range：\\ 20 ppm .. 2000 ppm carbon monoxide \\ 500 ppm .. 10'000 ppm methane CH₄ \\ 500 ppm .. 10'000 ppm LPG \\ \\ Sensing Resistance: 2KΩ- 20KΩ (100 ppm CH<sub>4</sub>)|
|{{anchor:mq131}}{{:sensor:g.png|Gas sensor}}\\ <color blue> ozone </color> |Winsen \\ **MQ-131** {{ :sensor:mq_135.png?100 |MQ-135}}|-|
|{{anchor:mq135}}{{:sensor:g.png|Gas sensor}}\\ <color blue>NO<sub>x</sub> \\ Ammonia NH₃ \\ alcohol \\ Benzene \\ smoke \\ CO₂ </color> |Winsen \\ **MQ-135** {{ :sensor:mq_135.png?100 |MQ-135}}|Detecting range：\\ 10 ppm .. 300 ppm Ammonia NH₃ \\ 10 ppm .. 1000 ppm Benzene \\ 10 ppm .. 300 ppm Alcohol \\ \\ Sensing Resistance: 30KΩ- 200KΩ (100 ppm Ammonia NH₃)|
|{{anchor:mq137}}{{:sensor:g.png|Gas sensor}}\\ <color blue>Ammonia NH₃</color> |Winsen \\ **MQ-137** {{ :sensor:mq_135.png?100 |MQ-135}}|Detecting range：\\ 5 ppm .. 500 ppm Ammonia NH₃|

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===== Arduino =====
Interfacing the **MQ-135** air quality sensor with an Arduino can be done either by reading raw analog signals or by using a dedicated library to obtain calibrated PPM (parts per million) readings.
==== Arduino wiring ====
^MQ-135^Pin^Arduino Pin^Description|
^VCC|5V|Power supply (the sensor has a built-in heater)|
^GND|GND|Ground|
^AOUT / AO|A0|Analog output (voltage level based on gas concentration)|
^DOUT / DO|D2 (Optional)|Digital output (goes high/low based on threshold)|
==== Arduino code ====
This code provides a raw reading from 0 to 1023, which is useful for basic threshold detection (e.g., triggering a fan or an alarm).

<code c>
int sensorPin = A0; // Select the input pin for MQ-135

void setup() {
  Serial.begin(9600); // Initialize serial communication
}

void loop() {
  int sensorValue = analogRead(sensorPin); // Read analog value (0-1023)
  Serial.print("Raw Air Quality Value: ");
  Serial.println(sensorValue);
  delay(1000); // Wait 1 second for next reading
}
</code>


{{tag>MQ MQ-2 MQ-3 MQ-4 MQ-5 MQ-6 MQ-7 MQ-8 MQ-9 MQ-131 MQ-135 MQ-137 Winsen Gas-sensor sensor arduino code alcohol C₂H₅OH Benzine_gas smoke LPG propane C₃H₈ hydrogen H₂ methane CH₄ Iso-butane Town_gas Ammonia NH₃}}

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