Before we start creating our own electronics to take readings from these sensors, we need to start with a little theory and testing to get a good understanding of how these sensors work and how we will be able to interact with them.
To start with, let's take a look at the mechanics and electronics used in the devices to know how the official device would have taken measurements from them (note that you do not have to disassemble your sensors here).
We will start with probably the simplest of all three—the rain gauge. If we unclip the top section, we will be able to notice a seesaw-like mechanism that carries water from the spout of the funnel in the top covered section to either the left-hand side or right-hand side of the sensor, depending on the position of the seesaw.
With each movement, the seesaw triggers a reed switch, a small switch that is activated using a magnet in the center of the seesaw that completes a circuit, which...