PCF8574 IIC/I2C 16 Pin Serial Interface LCD Display Adapter Module

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

MQ4 High Sensitivity Gas Methane (CNG) Detector Sensor Module is a simple to use MQ-4 High Sensitivity Gas Methane (CNG) Detector Sensor Module which can sense the presence of Compressed Natural Gas(CNG), methane(CH4), etc in the air. The module uses our MQ-4 sensor. It simplifies the interface to the odd pin spacing of the sensor and provides the interface through standard 4 x 0.1″ header pins. It provides an analog output corresponding to the concentration of the gases in the air and an easy to use digital output. The onboard potentiometer can be used to set the maximum gas concentration beyond which the digital output gets triggered. Just power the module with 5V set the threshold and you can start getting the gas concentration of the air around the sensor! An onboard LED signals the presence of any gas.