What is the difference between transformer and rectifier?

What is the difference between full wave bridge rectifier and a center tapped transformer?

• Answer:

  The obvious difference is that a full wave bridge rectifier is composed of four rectifier diodes while a center tapped transformer is a transformer (a component vastly different than a rectifier or a bridge rectifier) with a center tap in the secondary windings. The center tapped transformer is used with a full wave rectifier that is composed of a pair of diodes. One diode is connected to each end of the secondary, and they must be connected "the same" with either both cathodes or both anodes connected to those ends of the transformer. The load is connected to the center tap, and the other end of the load is tied to each end of the diodes. This will permit the load to receive unidirectional current. It will be DC, but will be "pulsating" DC because it isn't filtered. Half the secondary will be working on one half of the input sine wave, and the other half will be working on the other half of the input sine wave. Half the secondary volatage will be impressed across the load. In a full wave bridge, no center tap is required on that transformer. Rather, the bridge is connected across the whole secondary. Picture a diamond shape, and then connect the top and bottom across the secondary. The "left and right" sides are connected to the ends of the load. The diamond is actually the four diodes, and they must be connected in one of two ways for the bridge to work properly. On each half of the input sine wave, the current will leave the secondary, be routed through one diode, go out to the load and then come back through another diode to the other side of the secondary. On the other half of the sine wave, the current will leave the secondary, go through another (the "3rd") diode, go through the load, and come back thorugh another (the "4th") diode. The first two diodes conduct on one half the cycle, and the other two (the 3rd and 4th) conduct on the other half of the cycle. There are other questions here at WikiAnswers that explain the operation of these two types of rectification.