What is the purpose of a rectifier?

Rectifiers are used in electrical circuits to covert alternating current to direct current. They employ diodes, electrical devices that permit the flow of current in one direction only, to accomplish this conversion.

There are two types of AC/DC rectifiers: half-wave and full-wave units. Generally speaking, full-wave rectifiers offer a cleaner, more consistent signal conversion from alternating current to direct current than their half-wave counterparts. This comes at the cost of increased voltage drop across the rectifier connection, as full-wave rectifiers use four diodes for the conversion process, with two diodes active at one time, while half-wave rectifiers only have one diode.