The MQ 135 Air Quality Detector Sensor Module For Arduino has lower conductivity in clean air. When the target combustible gas exists, the conductivity of the sensor is higher along with the gas concentration rising. Convert change of conductivity to the corresponding output signal of gas concentration. The MQ135 gas sensor has high sensitivity to Ammonia, Sulphide and Benzene steam, also sensitive to smoke and other harmful gases. It is with low cost and suitable for different applications such as harmful gases/smoke detection

RS485 to TTL / TTL to RS485 converter is a module that allows the TTL interface of the microcontroller to be transferred to the RS485 module / MAX485 module. It is generally used for industrial automation. This module adds lightning protection design and anti-jamming design. When we use it in the field and carry out long distance transmission, we can Connect the GND end of the module to the ground so that lightning protection and anti-interference can be achieved. This Max485 to TTL module is online in Pakistan