How to read multiple sensors using only one Analog input pin

Many micro-controllers such as the D1 mini have few analog inputs so it is useful to be able to use multiple analog sensors using the same input pin. In this video, part of a upcoming series of tutorials, I will show you a simple way to do this.
The example sketch accompanying this tutorial can be found at:
medfizz.com/cab...
A more advanced version of this sketch using Blynk can be found at:
medfizz.com/cab...