ECE60US15 XP Power

A rectifier is an electrical device that changes alternating current (AC), which regularly changes direction, into direct current (DC), which flows in only one direction. The reverse process of converting DC to AC is done by an inverter. This process is called rectification, as it "straightens" the direction of the current. Rectifiers can take on various forms, including vacuum tube diodes, wet chemical cells, mercury-arc valves, stacks of copper and selenium oxide plates, semiconductor diodes, silicon-controlled rectifiers, and other silicon-based semiconductor switches. Historically, even synchronous electromechanical switches and motor-generator sets have been used. Early radio receivers, known as crystal radios, utilized a "cat's whisker" of fine wire pressing on a crystal of galena (lead sulfide) to function as a point-contact rectifier or "crystal detector." Rectifiers have many uses, often found as parts of DC power supplies and high-voltage direct current power transmission systems. Rectification may also serve in roles beyond generating direct current for power use. For example, rectifiers can function as detectors of radio signals. In gas heating systems, flame rectification is used to detect the presence of a flame. Depending on the type of AC supply and the arrangement of the rectifier circuit, the output voltage may require additional smoothing to produce a consistent, steady voltage. Many applications of rectifiers, such as power supplies for radio, television, and computer equipment, necessitate a steady, constant DC voltage, similar to that produced by a battery. In these applications, the output of the rectifier is smoothed by an electronic filter, which may consist of a capacitor, choke, or a combination of capacitors, chokes, and resistors, possibly followed by a voltage regulator to produce a steady voltage. More complex circuitry that performs the opposite function, converting DC to AC, is known as an inverter.