This is PL2303 CH340G USB To TTL(Serial) Converter For Arduino Nano Raspberry Pi USB to TTL / USB-TTL /STC microcontroller programmer / PL2303 in nine upgrades plate with a transparent cover Compatible with ARDUINO, RASPBERRY PI, AVR, PIC, 8051, etc. This USB-TTL converter is based on CH340G USB to Serial TTL converter chip. The module can be used for 3.3V logic level signals, and has the option to switch from 5V to 3.3V logic level using a 2 pin shunt (shortening jumper for specific pins) supplied with the 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

MQ3 MQ 3 MQ-3 Alcohol Detector Gas Sensor Module is a simple to use MQ-3 Alcohol Detector Gas Sensor Module which can sense the presence of Alcohol in the air. The module uses our MQ-3 sensor. It simplifies the interface to the odd pin spacing of the sensor and provides an interface through standard 4 x 0.1″ header pins. It provides an analog output corresponding to the concentration of the gas 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. Perfect sensing alcohol concentration on your breath just likes common breathalyzer. mq3 alcohol sensor working