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

A regulator is designed to maintain a constant output voltage or current despite variations in input voltage or output load conditions. Its primary function is to ensure that the power supply delivers a stable voltage to the components it powers, which is critical for the reliable operation of electronic circuits and devices.

Regulators can be found in various forms, including linear regulators and switching regulators. Linear regulators reduce the input voltage to a desired output voltage by dissipating excess energy as heat, while switching regulators utilize a method of rapidly turning the supply on and off to efficiently manage power. In either case, the regulator’s ability to adjust to changes in load or input conditions provides essential stability in electronic systems.

The other devices mentioned serve different purposes: transformers are used to change the voltage levels in AC circuits, rectifiers convert alternating current (AC) to direct current (DC), and filters smooth out fluctuations in the output signal. However, none of these components specifically perform the function of maintaining a consistent output level amid varying conditions like the regulator does.