Silicon Controlled Rectifiers - An Overview

Silicon Controlled Rectifiers
Silicon Controlled Rectifier
A silicon controlled rectifier is a three terminal electronic component.  It consists of an anode, a cathode and a gate. 

The device is similar to a diode, except that it needs to be switched on with an external voltage applied to the gate during the positive half cycle.  Once, the SCR has been trigerred, it "fires" and conducts as long as it is positively biased. 

In AC circuits, during the negative half cycle, the SCR switches off automatically. 

SCRS find application in applications where the current needs to be controlled.  They are used in many electronic equipments, such as inverters, converters, speed controller, etc.