Mq-135 Air Quality sensor Module Hazardous gas detection sensor alarm module Air pollution

Introduction to MQ-135 sensor:

The gas-sensitive material used for the MQ135 gas sensor is tin dioxide (SnO2), which has low conductivity in clean air. When the sensor is stored in the environment
In case of polluted gas, the conductivity of the sensor increases with the increase of polluted gas concentration in the air. The conductivity can be changed by using a simple circuit
Converts to the output signal corresponding to the gas concentration.
The MQ135 sensor is highly sensitive to ammonia, sulfides, and benzene vapors, and is ideal for smoke and other harmful monitoring. The sensor is detectable
Measuring a variety of harmful gases, it is a low cost sensor suitable for many applications.
Module application:
It is suitable for the detection of ammonia gas, aromatic compounds, sulfide, benzene series steam, smoke and other harmful gases. The test concentration range of gas sensing element is 10 to 1000ppm
Module features:
1. High quality double panel design with power supply indication and TTL signal output indication;
2. DO switching signal (TTL) output and AO analog signal output;
3. TTL output effective signal is low level. (When the output is low, the signal light is on and can be directly connected to the single chip microcomputer or relay module)
4. The analog output voltage is 0~5V, and the higher the concentration, the higher the voltage.
5. Good sensitivity for detecting air quality and harmful gases.
6. Four screw holes for easy positioning;
7. Overall dimension: 32mm(length)*22mm(width)*27mm(height)
8, with a long service life and reliable stability
9. Quick response and recovery features
10. Working voltage: 5V
Module instructions:
Explanation: Please preheat 20 seconds or so before use
Step 1: Supply 5V DIRECT current to the module (pay attention to the positive and negative poles are connected in reverse, otherwise the chip will be easily burned).
Step 2: If you choose DO and TTL high and low level output terminal, the output signal can be directly connected to IO port of single chip microcomputer or relay module. The potentiometer is used here to adjust the threshold value of output level jump.
Step 3: If you choose AO, analog output, so you don't have to worry about the potentiometer, directly connect THE AO pin to the input end of AD conversion or the MCU with AD function, it is ok. According to our experience: in the normal environment, i.e., without the environment of the gas being measured, set the sensor output voltage value of the reference voltage, at this time, AO the voltage at around 1 V, when measured gas sensors, every rise by 0.1 V voltage, the actual measured gas concentration increase 200 parts per million (in short: 1 PPM = 1 mg/kg = 1 mg/L = 1 x 10-6 are commonly used to represent the gas concentration, and solution concentration.) According to this parameter, the measured analog voltage value can be converted into the concentration value in the MCU. Note: If you are making precision instruments, please buy standard calibration instruments on the market, otherwise there will be an error, because the ratio of output concentration to voltage relationship is not linear, but tends to be linear.
Special reminder: after the sensor is energized, it takes about 20 seconds to preheat, and the measured data will be stable. The sensor heating is a normal phenomenon, because there is an electric heating wire inside, if it is hot, it will be abnormal

Module parameters:

1. Size :32mm(length)*22mm(width)*27mm(height)
2. Weight: 7 g
3. Main chip :LM393, MQ-5 gas sensor
4. Working voltage: 5 Volts DC
5. With signal output indication.
6. Double-channel signal output (analog output AOUT and TTL level output DOUT)
7.TTL output effective signal is low level (when the output is low, the signal light is on and can be directly connected to SCM)
8. The analog output is 0-5V voltage. The higher the concentration is, the higher the voltage will be
9. High sensitivity to butane, propane and methane
10. The reference concentration can be adjusted by the blue potentiometer. Rotate clockwise to reduce the reference concentration and counterclockwise to reduce the reference concentration

Degree of higher
11. It has a long service life and reliable stability
12. Quick response recovery feature

Test instructions:

VCC: connected to the positive pole of 5V power supply
DOUT: Digital signal output terminal, which can be directly connected to IO port of single chip microcomputer
AOUT: The output end of analog signal can be connected to the input port of AD conversion module to calculate the specific concentration value of gas
GND: Connected to the negative electrode of 5V power supply