How to Identify NPN and PNP Transistors using Multimeter?

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.

Read more related articles:

• Anode vs Cathode
• Voltage-PD-EMF
• Analog multimeter vs Digital multimeter
• Electrical measuring instruments 
• Types of measuring instruments
• Analog signal vs Digital signal

Thanks for Reading!