What maintains the output of the power supply at a constant level despite large changes in load current or input line voltage?

The regulator is the component that ensures the output of a power supply remains constant, even when there are significant variations in load current or changes in the input line voltage. Its primary function is to adjust the output voltage and maintain it at the desired level, providing stability to electronic circuits that require a steady voltage input for proper operation.

When there are fluctuations in load current, such as when devices connected to the power supply draw more or less power, the regulator compensates for these changes to keep the output voltage stable. Similarly, if the input voltage fluctuates, the regulator can adjust its operation to ensure that the output voltage does not deviate from its set point.

Other components, while essential to a power supply's overall operation, serve different functions. Converters primarily convert one form of energy to another, rectifiers are responsible for converting alternating current (AC) to direct current (DC), and amplifiers increase the amplitude of signals. None of these components inherently provide the voltage regulation necessary to maintain a constant output voltage under varying conditions like the regulator does.