This MQ137 module is a sensor board designed to detect NH3 Ammonia gas along with other gases. Sensitive material of MQ137 gas sensor is SnO2, which with lower conductivity (high resistance) in clean air. When the target sensitive gas exist, the sensor's conductivity is higher along with the gas concentration rising. The board comes with basic circuitry to change the conductivity or resistance to voltage and output it to header pins, DO and AO.
The figure above shows the connection of MQ sensor pin to Arduino Uno
MQ137 gas sensor has high sensitity to Ammonia, also to other organic amine. The sensor could be used to detect different gas which contains Ammonia, it is suitable for different application.
Warranty Period: 12 months
Features
Wide detecting scope
Fast response (less than 1s)
High sensitivity( 3%)
the circuit voltage: DC5V
Stable and long life
Operating Voltage is +5V
Detect/Measure NH3,Ammonia
Concentration: 5-500ppm (Ammonia)
Heater Resistance(RH): 31Ω±3Ω Room Temp
Heater consumption(PH): ≤900mW
Sensing Resistance(Rs): 2KΩ-15KΩ(in 50ppm NH3)
Sensitivity(S): Rs(in air)/Rs(5000ppm CH4)≥5
Slope(α): ≤0.6(R100ppm/R50ppm NH3)
Analog output voltage: 0V to 5V
Digital output voltage: 0V or 5V (TTL Logic)
Preheat duration: 20 s
Can be used as a digital or analog sensor
The sensitivity of digital output can be adjusted using on board potentiometer
The TTL output valid signal is low. (When the output is low, the signal light is on, it can be directly connected to the MCU or relay module)
The voltage of the analog output, the higher the concentration, the higher the voltage.