Amp Nerd

A decoupling capacitor can be the right value on a schematic and still be poorly connected on the board.

A crystal-based clock can be impressively stable without running at exactly its nominal frequency forever.

A thermistor changes resistance with temperature, but the direction depends on its type.

Switching off a coil can create a voltage much higher than its normal supply voltage.

A relay marked with a low coil voltage may switch a different voltage at its contacts, but those are separate specifications.

A MOSFET can have gate voltage above its threshold and still be a poor power switch.

The one-way-valve analogy helps explain a diode, but real diodes have voltage drop, leakage, capacitance, and switching limits.

A bare LED does not regulate its own current just because it is connected to a small battery.

A resistor marked 1W does not automatically consume one watt.

Removing the plug stops a source from supplying more energy, but it does not instantly empty every capacitor inside the equipment.