What is SCR? | Turn ON methods of SCR or Triggering Method of SCR

The Turn ON Method of SCR is the most important part of the correct function of the device. There are many different ways to trigger the SCR. This article will explain some of the more popular methods.

What is SCR?

SCR or silicon-controlled rectifier is a four-layer solid-state device. The SCR can be used as an ON/OFF switch for AC or DC signals. The device consists of a PN junction with two gate electrodes attached to it. When the gate voltage is below a certain value, the SCR is turned OFF. When the gate voltage is increased above this value, the SCR turns ON.

Turn ON methods of SCR

turn ON method of SCR

Turn On Methods of SCR

There are two ways to turn ON an SCR or silicon-controlled rectifier. The first is to use a gate voltage, and the second is to use a current.

Using a gate voltage is the most common method, and it is done by applying a voltage to the gate terminal of the SCR. This creates a field in the depletion region that turns on the SCR.

The other way to turn ON an SCR is by using a current. This is done by passing a current through the anode and cathode terminals of the SCR. This creates a magnetic field that turns on the SCR.

The Different Types of Triggering Methods for SCR

There are four different ways to trigger an SCR or silicon-controlled rectifier.

  • The first is called gate trigger, whereby a small current is passed through the gate leads to creating a voltage drop.
  • The second is called cathode trigger, and uses a similar method but with the voltage drop happening between the cathode and anode.
  • The third is called the anode trigger, which uses a reverse current flow to cause the voltage drop.
  • And finally, there is the base trigger, which employs a transistor to create the voltage drop.


There are several methods that can be used to turn on an SCR device, and the best method for any given application depends on the specific requirements of that application. In general, though, the most common methods for turning on an SCR are through a voltage or current trigger. If you need help determining which method is best for your application, please contact us and we will be happy to assist you.

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