What is a silicon controlled rectifier (SCR)?
A silicon controlled rectifier (SCR) is an electronic component that controls the flow of current like a switch. It has three connections: the anode, cathode, and gate. When a small current signal is applied to the gate, the SCR turns on, allowing current to flow from the anode to the cathode. Once the SCR is turned on, the current continues to flow until it decreases to a certain level, at which point it turns off. SCRs are commonly used to control high-power devices such as dimmable lights, heaters, and motors, allowing precise control of current flow. Testing the Functionality of an SCR with an Ohmmeter A basic test of SCR functionality, or at least terminal identification, can be conducted using an ohmmeter. Since the internal connection between the gate and cathode is a single PN junction, the meter should show continuity between these terminals when the red test lead is placed on the gate and the black test lead on the cathode, as shown in the figure below. All other continuity
