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Having a signal output instruction.
Dual signal output (analog output, and TTL level output)
TTL output valid signal is low. (Low-level signal when the output light can be directly connected to the microcontroller)
0 ~ 5V analog output voltage, the higher the concentration the higher the voltage.
Liquefied petroleum gas, natural gas, city gas has better sensitivity.
Has a long life and reliable stability
Rapid response and recovery characteristics
Suitable for home or industrial liquefied petroleum gas, natural gas, coal gas monitoring devices. Excellent resistance to alcohol, smoke interference
The sensors that use 5V or 6V for the internal heater do get warm. They can easily get 50 or 60 degrees Celcius.
The sensor needs a load-resistor at the output to ground. It's value could be from 2kOhm to 47kOhm. The lower the value, the less sensitive. The higher the value, the less accurate for higher concentrations of gas.
Some datasheets use the term "preheat", but it is the time to burn-in the sensor. This is meant to make the sensor readings more consistent. A time of 12 or 24 hours is usually used for the burn-in time.
The Burn-in is achieved by applying normal power to the sensor (to the heater and with the 'A' and 'B' pins connected, and with a load-resistor). In some special cases a specific burn-in is needed. See the datasheet if the sensor needs such a specific burn-in.
Starter Example: Sketch Template
- MQ Gas Sensor Brick with an LM393 and both digital and analog outputs.
- SEE the comments after "//" on each line below
- GND - GND
- +5V - VCC
- DOUT - 2
- AOUT - A0
#define LED_PIN 13 // define on-board LED
#define DIGITAL_IN_PIN 2 // define the digital input pin
#define ANALOG_IN_PIN A0 // define the analog input pin
int digitalValue ; // read digital value
float sensorValue; // read analoog value
void setup() /****** SETUP: RUNS ONCE ******/
pinMode (LED_PIN, OUTPUT) ; // Onboard LED
pinMode (DIGITAL_IN_PIN, INPUT) ;// digital input signal (Not actually required; INPUT is default)
pinMode (ANALOG_IN_PIN, INPUT) ;// analog input signal (Not actually required; INPUT is default)
Serial.begin(9600); // Start the Serial Monitor connection
Serial.println("YourDuino.com MQ Gas Sensor Test ");
sensorValue = analogRead(ANALOG_IN_PIN);
Serial.print("Analog value = ");
Serial.print(sensorValue), DEC; // display analog value
digitalValue = digitalRead (DIGITAL_IN_PIN) ;
Serial.print(" Digital value = ");
Serial.print(digitalValue), DEC; // display digital value
if (digitalValue == LOW) // Gas Sensor Module is active LOW when alarmed
digitalWrite (LED_PIN, HIGH);
Serial.println(" ALARM! ");
digitalWrite (LED_PIN, LOW);