HOW TO TEST YOUR TRANSISTORS WITH YOUR MULTIMETERS

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Introduction: HOW TO TEST YOUR TRANSISTORS WITH YOUR MULTIMETERS

About: I like playing football,basketbal ,making circuits and doing science.

Hello everyone!!

In this instructable I will be telling you how to test your transistors with the help of your multimeters.

Now, forget those circuits used for testing transistors and now its time to get easy and practical.

Step 1: MOTIVATION

I had been working on an instructable (https://www.instructables.com/id/HOW-TO-MAKE-DANCING-LEDS/)
And it had been working well. But when I thought to upload its video , it didn't work!

I was really shocked what had happened to it. The resistors were fine and the capacitors too. So, I decided to check my transistor as either of them would not be working.
I got the malfuctioned one replaced and now it works!!!


So,I thought to share this thing with others and I ended  up making this instructable.

Step 2: REQUIRED THINGS

The things you require are very simple.

First, you need a multimeters and Secondly, of course transistors you  want to test.

Step 3: THE TRANSISTORS

Now, comes the part of testing the transistors.

Let me tell you about the NPN transistor, it has the collector and emmitter as negative and the base as positive, which is just opposite in PNP transistors.

First, set the multimeter on the transistor testing mode.

Now, take the leads of the multimeter and connect it to the leads of the transistors as shown in the picture. The negative lead to the negative terminal and positive lead to the positive terminal.
There will be a reading in the multimeter.

Now, connect the negative lead to the other negative terminal.Again the multimeter shows a reading.

The reading in both the cases is almost equal.

Step 4: DETECTING a BAD TRANSISTOR

Now, connect the leads to both the  negative terminals. If the multimeter shows 1 as a reading then the transistor is just fine.


 And if this is not the case then the multimeter produces a buzzing sound and shows 000 as a reading ,and the transistor is just too bad for use as shown in the video.

Step 5: A PNP TRANSISTORS

Well I did not have a PNP transistor so I am just giving the notes for testing it. Its a NPN transistor and I just used to instruct you how to test a PNP transistor.

All you have to do is to connect the leads to the oppsite terminals.

The PNP transistor will give a reading only when you connect the positive lead in the middle and the negative lead in the sides.

So, you can use the above tests to distinguish between a NPN and a PNP transistor.

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    14 Discussions

    0
    benzolio
    benzolio

    Question 7 months ago

    In the second to last sentence you said "The PNP transistor will give a reading only when you connect the positive lead in the middle and the negative lead in the sides." That sounds like you are saying it is the same as an NPN, but that can't be correct, and it contradicts the previous sentence. Have you reversed "negative" and "positive" in this sentence? If so, could you consider revising this post?

    I realize this is a post from years ago, and the original poster may not be watching here anymore, or may be unable to edit. For anyone else wondering about this, I have checked with some brand new 2222A NPN transistors and everything matches this test procedure, but for my brand new 2907A PNP transistors polarity is reversed, as stated in the third to last sentence of the above procedure.

    Multimeter readings show up with the negative probe on the base of a PNP with the positive probe on either emitter or collector.

    0
    ErnestoS
    ErnestoS

    3 years ago

    So my transistor might be faulty:

    Resistance between the diode in Base-Emitter is fine (600-700 ohms)
    Resistance between the one in Base-Collector is infinite

    I guess the collector is more probably to burn since it is the one that sustain all the heat to dissipate.

    I have two RF Power Transistors (out of ham radio transceiver) I am trying to test. I get 710 ohms from Emitter-Collector (but open loop in reverse). Otherwise they test normal. They are very hot in circuit. What is your opinion?

    0
    cdanila11
    cdanila11

    Reply 5 years ago

    If they perform as expected, mount them on heatsinks (with attached fans for extra cooling if they are still too hot) and watch out not to exceed their peak currents.

    0
    I hater
    I hater

    5 years ago on Step 5

    Hello prajal12

    My receiver Kenwood KR-V127R sound worse than a very small portable player, I suspect the power output transistors are dying will this test confirm that.Thanks

    this is a good trick! have you ever found a transistor that did not have the base as the middle pin?

    0
    joshuajfrancis
    joshuajfrancis

    Reply 5 years ago on Introduction

    Why yes of course!In my sony str-de425 the transistors mn2488 and mp1620 both have the base as the first and emitter and collector as middle and 3rd it is very confusing. :)

    0
    Roohan93
    Roohan93

    Reply 5 years ago on Introduction

    BD 140 and it's similar types have base on 3rd pin

    0
    pranjal12
    pranjal12

    Reply 7 years ago on Introduction

    No! I have never seen one but if u have it then you can upload a picture of it and I will tell u whether u can test it or not.

    its just fine.could you tell me why the multimeter shows 1 when the transistor is in good condition?

    0
    Arghodeep Paul
    Arghodeep Paul

    Reply 6 years ago on Introduction

    Hey vignesh !!

    You asked a good question..

    When we measure resistance of an object then a multimeter shows

    the value.

    but have you wondered if the object is a insulator like wood,plastic ++

    then the resistivity can't be measured cause the electricity can't flow

    through them at all because of their infinite resistance.

    In this case expensive multimeters will display "O.L." (open loop).

    and cheap meters will display only '1' means the same(infinite resistance/open loop).

    Hope it helps :)