How to Determine the Type of TRANSISTOR NPN and PNP with Digital Multimeter – Transistor is one of the Semiconductor Components that are often used in Electronic circuits. Transistors have a variety of functions needed by an electronic circuit. These functions include amplifiers, recessers, switches, mixers and stabilizers.
In general, transistors can be divided into two types, namely Bipolar Transistor and FET Transistor. Both transistors have three terminal legs but have different names. Bipolar transistors use the names Terminal Base Foot (B), Collecttro (K), Emitter (E) while FET Transistors use the names Terminal Gate Foot (G), Drain (D) and Source (S). Npn transistors and PNP transistors that we will discuss in this article are types of transistors that are classified as bipolar transistors, which are transistors that have two polarities in carrying electric current.
How to Determine the Type of NPN and PNP Transistors with Digital Multimeter
NPN transistors and PNP transistors have almost the same physical form and are very difficult to distinguish without the use of measuring instruments or multimeters, unless we get the transistor datasheet based on the code printed on the transistor body in question. In this article, we will discuss how to find out the types of NPN and PNP transistors by using a Digital Multimeter.
Before we start, we need to know the position of the base terminal legs, collectors and transistor emitters. Here are some references to the transistor terminal foot layout that is commonly used by various electronic circuits. The layout of the transistor is based on the shape of the transistor package:
In principle, in the internal transistor consists of two diodes, if the type of transistor is PNP then in the internal transistor consists of a PN diode in the Emitter-Base terminal and another is an NP diode at the Base-Collector terminal. With this principle, we can easily distinguish the type of NPN or PNP transistor by using diode mode measurements on digital multimeters.
In the Diode Mode, the Multimeter screen will display a certain voltage when the red (positive) probe is connected to the Anode terminal and the black (negative) probe on the Cathode terminal. Conversely, the Multimeter screen will display ‘NOL’ when the red (positive) probe is connected to the Cathode terminal and the black (negative) probe to the Anode terminal.
After knowing the position of the transistor terminal foot and the basic principle of a transistor, let’s start preparing the transistor components that we will test and the Digital Multimeter as the tester.
Steps to determine the type of NPN transistor
The following are the steps to determine the NPN Transistor:
- Set the position of the switch in Diode mode.
- Connect the Red Probe (+) to the Transistor Base terminal.
- Connect the Black Probe (-) to the Transistor Emitter terminal. The Multimeter screen will show a certain voltage value.
- Move the Black Probe (-) to the Transistor Collector terminal. The Multimeter screen will show a certain voltage value.
- If the 3rd and 4th steps show a certain voltage value, then the transistor can be ascertained is an NPN type transistor.
Emitter = Semiconductor Type N = Cathode on Diode.Base = Semiconductor Type P = Anode on Diode.Collector = Semiconductor Type N = Cathode on Diode.
Steps to determine the type of PNP transistor
The following are the steps to determine the PNP Transistor:
- Set the position of the switch in Diode mode
- Connect the Black Probe (-) to the Transistor Base terminal.
- Connect the Red Probe (+) to the Transistor Emitter terminal. The Multimeter screen will show a certain voltage value.
- Move the Red Probe (+) to the Transistor Collector terminal. The Multimeter screen will show a certain voltage value.
- If the 3rd and 4th steps show a certain voltage value, then the transistor can be ascertained is a PNP type transistor.
Emitter = Semiconductor Type P = Anode on diode.Base = Semiconductor Type N = Cathode on diode.Collector = Semiconductor Type P = Anode on the diode.
Read also Definition of Transistors and Types of Transistors
Basically, the above test uses the principle of diode testing on a transistor that is if the Red Probe (Positive) is connected to the Anode and the Black Probe (Negative) is connected to the Cathode then the multimeter will show a certain voltage value. Conversely, if the Red Probe on the Cathode and the Black Probe on the Anode then the multimeter will not show any voltage.
