For example, you can insert a resistor, a capacitor, an inductor, a diode, or a transistor and get a readout of which pin is which. It seems like magic, but [Andreas Spiess] did the research on ...

[Fileark] built and ESC using an Arduino and has a couple of posts explaining the concept and demonstrating how it works. His test circuit uses six 2N2222 transistors to protect the Arduino from ...