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 ...
The mosfet is off if the input voltage is normally less than \(2.0 V\). By looking at a circuit diagram of a transistor switching circuit, you should be able to say what the circuit is used for ...