MQ-2 Smoke/LPG/CO Gas Sensor Module
4.1V~5V (not more than 5.1V, when using charger power supply, car charging power supply or DC-DC power supply, pay attention to the power supply voltage and ripple voltage, can string a diode)
Pre-set value is 3.3V. Just push a key to change the voltage settings and the data will be saved. When the voltage is below the set value, it will buzzer with red LED light.
Computer is now in your wallet. Raspberry Pi, the credit-card sized computer is capable of many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video. It can run several flavors of Linux and is being used to teach kids all over the world how to program.