What converts the alternating current input signal to a pulsating direct current?

The conversion of an alternating current (AC) input signal to a pulsating direct current (DC) is accomplished by a rectifier. Rectifiers are essential components in power supply circuits as they serve to change the AC waveform—which varies between positive and negative cycles—into a unidirectional flow of current. This process is necessary because many electronic devices operate on DC power.

A rectifier typically uses semiconductor diodes, which allow current to flow in only one direction. By selectively conducting during the positive half-cycles of the AC signal and blocking the negative half-cycles, the rectifier effectively produces a pulsating DC output. This output still has some ripples due to the nature of the conversion but is fundamentally a step toward creating a usable DC voltage.

Some rectifiers, like full-wave or half-wave rectifiers, vary in their design but still serve the same primary function: the transformation of AC to a pulsating DC. The subsequent role of additional components, such as capacitors, is to smooth out the pulsating DC to provide a more stable and constant output voltage.