How to check the transistor

In the world of modern technology can not do without transistors. They come in various electronic devices, they can be found in phones and radios, in computers and cars. Sometimes there is a need to check their performance, and then it is useful to know how to check the transistor and what is needed for this. The material presented in the article highlights this issue.

Transistors and their types

This device is an electronic device that is used in electrical circuits in order to amplify the original signal. It is made of semiconductor materials. There are 2 types of transistors: field and bipolar, which are controlled not by voltage, but by current. In addition, they can be low-power and powerful, low-frequency and high-frequency. They differ in size and design of buildings.

Often when mentioning transistors, they mean bipolar versions of them, manufactured from germanium or silicon. Bipolar they are called because they work with electrons (charge carriers) and holes. One of the areas of the transistor, located on the edge, is called the emitter, the intermediate one is the base, and the other, also located at the edge - the collector. So 3 electrodes create 2 pn junction: the collector, located between the collector and the base, and the emitter, which is located between the emitter and the base. The transistor can be in the "on" state and "off", and the transition between them is carried out by means of electrical signals.

The main purpose of transistors is the generation, amplification and transformation of electrical oscillations. But, like any technical device, a transistor can fail. You need to know how to test the transistor so that the result is reliable. For this purpose, multimeters are used.

Checking transistor by tester

The multimeter (the same tester) is a special combined device, which is used for electrical measurements. It combines several functions: at least it combines an ammeter, a voltmeter, an Ohmmeter. There are analog and digital instruments, light, portable and stationary, which combine many possibilities.

A multimeter is a device that tells you how to test a transistor and do it visually. The tester allows you to conduct a test while measuring the low resistance in the circuit, while signaling is sounded, either audible or light.

Before considering the process, how to test the transistor with a tester, it is important to know that these devices are divided into 2 types in accordance with the arrangement of layers with different conductivity. So there are semiconductors with electronic conductivity (pnp), and semiconductors with hole conductivity (p-).

To check the forward resistance of the transition, connect the "minus" of the multimeter to the base, and connect the "plus" one by one to the emitter and the collector. When measuring the reverse resistance, change the position of the "minus" and "plus". To measure the transition resistance of pnp, repeat the same steps, only by changing the polarity beforehand. During the check of the transitions from the base to the emitter and the collector, they must only call 1 way.

Since it is possible to check the transistor with a multimeter, but this does not give an absolute guarantee in the serviceability of the device, for greater confidence it should be checked in active mode. In this case, the result will be more reliable.

And yet: how to check the transistor and be sure of the results? For a bipolar device, for convenience, it is possible to count each of its transitions as analogues of a diode, having first checked their serviceability. There are powerful transistors that include a damper built-in diode between the emitter and the collector, and a protective resistor between the base and the emitter. At any polarity of the multimeter on such a transistor there will be a resistance from thirty to fifty ohms and it will sound like a diode between the emitter and the collector. This indicates the serviceability of the part.