How to Identify NPN and PNP Transistor using Multimeter
How to Identify NPN and PNP Transistor (BJT) using Multimeter?
Imagine from your component box, you have picked couple of Bipolar Junction Transistors (BJTs) and you don't know whether they are NPN or PNP type transistors... (Almost everyone would have face this problem)
In this post, we will discuss about how to find out the NPN and PNP transistor using multimeter...
Before proceeding further, let us refresh about how to identify the transistor terminals.
Identifying BJT Terminals:
We know that the Bipolar junction transistor has three terminals namely
- Emitter (E)
- Base (B)
- Collector(C)
The transistors are available with various packages in the market. Let us discuss about the TO-92 package.
Keep the transistor such that the flat surface facing towards you as shown in the below figure:
Now starting from left, mark like 1,2 and 3. They are respectively
- Emitter (E)
- Base (B)
- Collector(C)
The schematic symbol of the BJT is given below:
Identifying BJT Types:
Both NPN and PNP transistor looks similar in physical appearance. We can not differentiate by seeing them. We need a multimeter to identify the type of BJT.
Remember the following points:
- The transistor internally has two diodes (NPN ≡ N - P - N ≡ NP Junction + PN Junction and PNP ≡ P - N - P ≡ PN Junction + NP Junction).
ie,Emitter to base is one PN junction ( diode) and Base to collector another PN junction (diode). - In the diode mode, the multimeter will show the voltage when we keep the positive probe of the multimeter to the anode of the diode and negative probe to the cathode.
- If the multimeter positive probe is connected to the cathode of the diode and the negative probe to the anode, then it will not give any voltage (showing zero).
Steps to identify the NPN type transistor:
- Keep the Multimeter in the Diode mode.
- Keep the positive probe to the center pin (Base) of the transistor.
- Touch the negative probe to the pin-1 (Emitter). You will see some voltage in the multimeter.
- Similarly touch the negative probe to the pin-3 (collector) with respect to the pin-2. You will see some voltage in the multimeter.
- It will ensure that it is a NPN transistor. The logic behind this is, in NPN transistor
Emitter (E) - N type material - Equivalent to cathode of the diode
Base (B) - P type material - Equivalent to anode of the diode
Collector(C) - N type material - Equivalent to cathode of the diode - If the multimeter positive probe is connected to anode and negative probe is connected to cathode, then it will show voltage. If the connections are interchanged it will not show any value.
Steps to identify the PNP type transistor:
- Keep the Multimeter in the Diode mode.
- Keep the positive probe to the pin-1 (Emitter) of the transistor.
- Touch the negative probe to the center pin (Base). You will see some voltage in the multimeter.
- Similarly touch the negative probe to the center pin (Base) with respect to the pin-3 (collector). You will see some voltage in the multimeter.
- It will ensure that it is a PNP transistor. The logic behind this is, in PNP transistor
Emitter (E) - P type material - Equivalent to anode of the diode
Base (B) - N type material - Equivalent to cathode of the diode
Collector(C) - P type material - Equivalent to anode of the diode - If the multimeter positive probe is connected to anode and negative probe is connected to cathode, then it will show voltage. If the connections are interchanged it will not show any value.
With the help of above mentioned steps we can identify NPN and PNP transistor using multimeter. How can we ensure that the transistors are in good condition and failed?. Please read the post How to test transistor using Multimeter?
You may also like to read:
How fluorescent lamp works?
How to Control the Speed of DC Shunt Motors?
Comparison between Electrical and Magnetic Circuits
MOSFET vs JFET Comparison
Please leave your comments below...
Thanks for that helpful information
Thank you very much!!
Doesn't this article ignore the difference between TO-92A, TO-92B and TO-92C?
yep and if you don't know what the base is... good luck
Tt was my great problem.Thank you.
Thank you so much..this is great..
very well
Thanks, but how to identify pins EBC
You'll have to note the Model No. and look up the data sheet in order to find that out.
keep the flat surface towards you ... from left side 1-E 2-B 3-C
collector is less oum than emitter when tested by AVO ..
It mean collector is nearest to zero oum than emitter ..
use AVO: And hold the first lead to the "base" the other lead move it to collector time and emitter another time .. the collector should read less oum than the emitter ..
thanks that's helpful information
Thanks for giving very useful informations.
so helpful thanks@
obio
Thanks for informing and if possible crystal how to check by multimeter informarion ptovide so we learn
Thank you got the point.
I found this article useful. Many thanks to the author.
Thanks a lot...
I appreciate. This explanation is very usefull
Thanks for provided good information
THANK YOU FOR EVERYTHING
Thank you. Now i get what i want.
Very useful information is explained very clearly. Thank you!
Great! Thanks so much.
thanks a lot ..nice eplanation
thank you
Thank you very much
Thanks
Thnks
Nice explanationa
Very nice sir you do solve my large problem
I am very thsnksfull to you
This Information about transistor is very good . But I have a question
As you show the pin diagram identification in fig for EBC. But some have CBE as respect series. This is confusion about pin out. Identification
The information is very useful thanks
if suppose in condition where i dont have the npn transister and i have pnp transister but i need npn transister in the circuit then can i use the npn transister
It helped me a lot. Thanks
Thanks for teaching /providing in simple & perfect manner. Really very useful ....
How to identify collector or emitter
THANKS, YOU HAVE MADE IT VERY SIMPLE TO UNDERSTAND
Thanks for this wonderful info. It helpful
Thanks, this is going to help me a lot in my upcoming exams
So wonderful its so helpful for me and rest