In order to show a simple ADC usage (with a little help of a PWM source), we will see how we can detect a dangerous gas using an analogue sensor that is shown here:
The devices can be purchased at or http://www.cosino.io/product/mq-2-gas-sensor by surfing the Internet.
We can get the datasheet of each GAS sensor at http://gas-sensor.ru/pdf/combustible-gas-sensor.pdf.
This sensor acts as a variable resistor according to the gas concentration, so they can be easily read with a normal ADC. Looking carefully at the datasheet of the gas sensor, we can see exactly how this sensors varies its internal resistance according to the gas ...