silicon-controlled rectifier

A silicon-controlled rectifier (SCR) is a type of thyristor, a semiconductor device with four layers and three p-n junctions. It functions as a solid-state equivalent of the thyratron vacuum tube, hence its name, which combines "thyratron" and "transistor".1

SCRs are commonly used to convert alternating current (AC) to direct current (DC) and are integral to devices that regulate motor speeds, liquid levels, temperatures, and pressures. These devices exhibit two stable states: an "off" state with high resistance and low current, and an "on" state with low resistance and high current. Their ability to switch between these states efficiently makes them valuable in a wide range of applications, from household appliances to high-voltage power transmission.1