In a power supply, what does the rectifier do?

The rectifier in a power supply is designed to convert alternating current (AC) into direct current (DC). However, the output from a rectifier is typically not pure DC; it is pulsating DC. This pulsating DC has variations in voltage, which means it still contains some AC characteristics - specifically, it is composed of a waveform that rises and falls regularly.

The rectification process involves the use of diodes, which allow current to flow in one direction, effectively blocking the negative half of the AC waveform and only letting the positive half pass through. As a result, the output is a series of positive voltage peaks, resulting in pulsating DC.

Once the rectifier provides the pulsating DC, additional components, such as filters, may be used to smooth out the output and remove remaining AC ripple to achieve a more stable DC voltage. However, the rectifier's fundamental role in the process is to perform the initial conversion from AC to this form of pulsating DC.