How to Identify NPN and PNP Transistors using Multimeter?

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In an earlier article, we have studied the difference between PNP and NPN transistors with multiple specifications and symbolic representation.

In this article, we will study the test of transistors by using a digital multimeter.

Identify NPN and PNP Transistors using Multimeter

Following are the basic steps that you can use to check the transistor type.

  • Firstly, connect two probes (i.e. positive and negative) to the multimeter.
  • Set the multimeter in the Diode mode operation.

Note: These two steps are common for PNP and NPN transistors.

Steps to identify NPN transistor

  • Keep the postive probe on the base terminal (pin-2) of the transistor and negative probe on emitter terminal (pin-1) of the transistor. After that, you will see some voltage reading in the multimeter.
  • Similarly, keep the positive probe at the same position (i.e. base terminal). And touch the negative probe to a collector terminal (pin-3) with respect to the base terminal (pin-2). You will get voltage reading in the multimeter.

Steps to identify PNP transistor

  • Keep the positive probe to emitter terminal (pin-1) of the transistor. And touch the negative probe to the base terminal (pin-2) of the transistor. Thus, multimeter will show voltage reading.
  • Similarly, keep the negative probe at the same position (i.e. base terminal). And connect positive probe to a collector terminal (pin-3) with respect to the base terminal (pin-2). You will get result.

Note: If the positive probe is connected to the anode and the negative probe is connected to the cathode, then the reading will automatically show in a digital multimeter. Otherwise, the connections are interchanged, the multimeter will not show any value.

This is all about the simple steps to test and identify transistors in an electric circuit.

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