In the world of modern technology can not do without transistors. They are included in various electronic devices, they can be found in telephones and radios, in computers and cars. Sometimes it becomes necessary to check their operability, and then it is useful to know how to check the transistor and what is needed for this. The material presented in the article covers this issue.
Transistors and their types
This device is an electronic device that is used in electrical circuits to amplify the original signal. It is made from semiconductor materials. There are 2 types of transistors: field-effect 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 vary in size and design.
Often when mentioning transistors, bipolar varieties of them are made of germanium or silicon. They are called bipolar 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 - the base, and the other, also located on the edge - the collector. So 3 electrodes create 2 pn junctions: collector located between the collector and the base, and emitter, which is located between the emitter and the base. The transistor can be “on” and “off”, and the transition between them is carried out using electrical signals.
The main purpose of transistors is the generation, amplification and conversion of electrical oscillations. But, like any technical device, the transistor can fail. You need to know how to check the transistor so that the result is reliable. For this purpose, multimeters are used.
Transistor Tester Check
A multimeter (aka a tester) is a special combined device with which electrical measurements are carried out. It combines several functions: at least it combines an ammeter, voltmeter, and ohmmeter. There are analog and digital devices, light, portable and stationary, which combine many features.
A multimeter is a device that tells you how to check the transistor and do it clearly. The tester allows you to make a call when measuring low resistance in the circuit, while an alarm sounds, sound or light.
Before considering the process of how to test a transistor with a tester, it is important to know that these devices are divided into 2 types according to the arrangement of layers with different conductivities. So there are semiconductors with electronic conductivity (pnp), and semiconductors with hole conductivity (p-).
To check the direct resistance of the transition, connect the minus of the multimeter to the base, and connect the plus to the emitter and collector in turn. When measuring the reverse resistance, change the position of the “minus” and “plus”. To measure the transition resistance pnp, repeat the same steps only after changing the polarity first. During the verification of transitions from the base to the emitter and collector, they should only ring in one direction.
Since it is possible to check the transistor with a multimeter, but this does not give a 100% guarantee that the device is in good working order, for greater certainty, it should be checked in the 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, one can count each of its junctions as diode analogs, having previously 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. With any polarity of the multimeter on such a transistor, there will be resistance from thirty to fifty ohms and it will ring between the emitter and the collector as a diode. This indicates the serviceability of the part.