Build Your Own Arduino Voltmeter Circuit and Voltage Divider Which Can Measure Voltages From 0V to 30V, Including 12V. Visit To learn More.

This project is a great example. [Scott Daniels] takes a look at the other voltage measurement options available to AVR chips used by Arduino.

It’s an easy to build high voltage power supply that interfaces with an Arduino. After harvesting a flyback from the power board of a CRT, [Andrew Moser] added a new primary coil to the transformer.