Passive components are modules that do not require power to operate other than the available alternating current (AC) circuits that are connected. Passive modules cannot collect energy and are not energy sources. Typical passive components are chassis, inductors, resistors, transformers, or capacitors. Passive components usually cannot increase power or amplify the signal. However, the current or voltage can be increased through an LC circuit that stores electrical energy from the resonant frequency, or a transformer that acts as an electrical insulator.