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How to Measure Any DC Voltage with an Arduino ARDVC-01

Using this code and proper hardware, you will be able to measure any DC voltage using Arduino. You simply need two resistors to use them as a voltage divider, which has been explained in the video. To protect the Arduino against excess voltage at the analog pin, you need a 5.1V Zener diode. But if you are sure that the voltage never goes above your limit, you do not need a Zener diode.