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.

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 ...

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.