What is a bipolar transistor and how to check the multimeter

Transistor - this is probably the most common and the most important element in all modern electronics, and often there is a need to verify the integrity and efficiency of the element. In this article I'll show you how to perform a test of the bipolar transistor with a multimeter.

What is Bipolar Transistor

Before you take the meter and proceed to checkout, let's see what is a bipolar transistor. Without going into details it can be said that such a transistor is made up of two P - N junctions, as is well known, such a transition passes current only in one direction. On this principle all the diodes built.

There are two types of bipolar transistors:

P-N-P transistor

The material, which separates the other two absolutely identical material, called a base, the two remaining output are called emitter and collector. When this base is located in the middle.

Schematically, such a bipolar transistor is denoted as follows:

In another variation of the bipolar transistor

already material P is N buffer for two electrodes. The principle of operation of such a transistor is similar to the above except that the transistor current flows in the reverse direction.

Schematic symbol N-P-N transistor is:

By and large, the transistor can be represented as two connected diode:

This means that you can check the transistor as two diodes. Let's check this option in practice.

The next transistor will be considered as an example:

Read its markings. In our case it KT815. Now open the internet and look for information on our transistor. We are interested in the technical description of the product. In English this is called a datasheet. Throughout this document we have with you will be interested pinout:

Now it is clear where our transistor is the base, emitter and collector. And that is implemented N-P-N junction.

Now, remember our figure connected with diodes. So it turns out if the product is working, we will see a voltage drop, if will make the red probe (plus) to the base, and the black lead (minus) to the collector or to the emitter. But if you put a minus to the base, but a plus to the collector or emitter, it will burn on the multimeter to "1".

Now we take our multimeter probes inserted and select a dial (as shown in photo).

And proceed to the immediate inspection:

As seen from the above presented photo voltage drop equal to 0.477. From this option, you can even determine what material is carried out the product. For example, if the voltage drop will be in the range 0.3 - 0.4 volts, then the germanium is used, if you see a value from 0.5 to 0.7, in a transistor used silicon.

Now we change probes seats and check the reverse voltage drop across P-N junction and in this case we should see on the multimeter to "1".

As is clear from the test transistor is fully functional and can be used in any of your hand-made article. If you have seen when checking the zeros on the multimeter, then this would indicate that the transistor is faulty and it can be safely thrown in the trash.

conclusion

As you can see, the checking of such elements as the bipolar transistor is very simple and most importantly does not take long for you to find a datasheet on your product.

After all, in addition to ordinary transistors are also components when in the same housing can be located several transistors or a transistor and a normal diode, or the item is in your hands, which you have identified as a transistor can be chip.

So the most important thing is to find a technical description and verification will take place quickly and easily.

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