The resistor values (R1&R2) in the circuit diagram provide some over-voltage protection then measuring low voltages. Keep it in mind that any input voltage higher than about 55V could fry the Arduino.

(circuit diagram of the wind sensor from modern device) The $17.00 wind sensor from modern device runs fine between 5 and 10 volt dc, but a regulated 5V DC supply is preferred for microcontroller ...

I have a schematic of a purely analog sensor like this, but the arduino gives us an opportunity to focus on the “shape” of the field, or any kind of pulsed frequency if that’s available.

Current is a measure of how much electric charge flows through a circuit. The more charge that flows, the bigger the current. Current is measured in amperes. The symbol for ampere is A. For ...