Before repairing electronic device Or the assembly of the scheme is to make sure in good condition of all items that will be installed. If new parts are used, you need to make sure of their performance. The transistor is one of the main components of the elements of many electrical strokes, so it should be squeeze in the first place. How to check the multimeter transistor will tell in detail this article.
The main component in any electrical process is a transistor, which under the influence of the external signal controls the current in electrical chain. Transistors are divided into two types: field and bipolar.
The bipolar transistor has three outputs: base, emitter and collector. A short size is fed to the database, which causes a change in the emitter-collector zone of the resistance, which leads to a change in the flowing current. The current flows in one direction, which is determined by the transition type and corresponds to the polarity of the connection.
Transistor this type Equipped with two P-N transitions. When electronic conductivity (N) predominates in the extreme field of the device, and in the average - hole (P), then the transistor is called N-P-N (inverse conductivity). If on the contrary, then the device is referred to as the type P-N-P transistor (direct conductivity).
Field transistors have characteristic differences from bipolar. They are equipped with two working conclusions - source and drain and one control (shutter). IN this case A voltage is affected by the shutter, and not the current, which is characteristic of bipolar type. The electric current passes between the source and drain with a certain intensity, which depends on the signal. This signal is formed between the shutter and the source or shutter and flow. Transistor of this type can be with managing P-N transition or with an isolated shutter. In the first case, the working conclusions are connected to the semiconductor plate, which can be p- or n-type.
The main feature field transistors It is that their management is not provided with current, but voltages. The minimum use of electricity allows it to be used in radio components with quiet and compact power sources. Such devices may have different polarity.
How to check the multimeter transistor
Many modern testers are equipped with specialized connectors, which are used to test the efficiency of radio components, including transistors.
To determine the working state of the semiconductor device, it is necessary to test each item. Bipolar transistor has two r-N transition In the form of diodes (semiconductors), which are counted connected to the database. From here one semiconductor is formed by the leads of the collector and the base, and the other emitter and the base.
Using the transistor for assembling the circuit board, it is necessary to clearly know the purpose of each output. Improper placement of the element can lead to its burden. With the help of the tester, you can find out the purpose of each output.
Important! This procedure It is possible only for a good transistor.
To do this, the device is translated into the measurement mode to the maximum limit. Red dipstick should touch the left contact and measure resistance on the right and middle conclusions. For example, the display shows the values \u200b\u200b1 and 817 ohms.
Then the red dipstick should be transferred to the middle, and with the help of black to measure resistance on the right and left conclusions. Here the result may be: infinity and 806 ohms. Red probe translate to right contact and perform measurements of the remaining combination. Here, in both cases, the display shows the value of 1 ohm.
Making a conclusion from all measurements, the base is located on the right conclusion. Now, to determine other conclusions, a black probe is needed to be installed on the database. In one output, the value of 817 ohms appeared - this is an emitter transition, the other corresponds to 806 ohms, a collector transition.
Important! The resistance of the emitter transition will always be greater than the collector.
How to ring a multimeter transistor
To ensure in good condition of the device, it is enough to learn the direct and inverse resistance of its semiconductors. To do this, the tester is transferred to the measurement mode of the resistance and is installed on the limit 2000. Next, it should be squeezed every pair of contacts in both directions. This is how six measurements are performed:
- the connection "base collector" should conduct electricity in one direction;
- the "base-emitter" compound conducts electrical current in one direction;
- the "Emitter-collector" connection does not conduct an electric current in any direction.
How to nick multimeter transistors whose conductivity is P-N-P (Emitter transition arrow is directed to the database)? To do this, it is necessary for a black dipstick to touch the database, and the emitter and collector transitions are alternately concerned. If they are working, a direct resistance of 500-1200 ohms will be displayed on the tester screen.
To check the reverse resistance, the red dipstick should touch the database, and black alternately to the outputs of the emitter and manifold. Now the device must show in both transitions a large resistance value, displaying "1" on the screen. So, both transitions are good, and the transistor is not damaged.
This technique allows you to solve the question: how to check the multimeter of the transistor without falling out of the board. This is possible due to the fact that the transitions of the device are not extended by low-level resistors. However, if during measurements the tester will show too small values \u200b\u200bof direct and reverse resistance of the emmitry and collector transitions, the transistor will have to fall out of the circuit.
Before you check the N-P-N multimeter, the transistor (the arrow of the emitter transition is directed from the base), the red probe tester to determine the direct resistance is connected to the database. The performance of the device is checked as the method as the transistor with the conductivity of P-N-P.
About the malfunction of the transistor shows a breakdown of one of the transitions, where much importance is detected or reverse resistance. If this value is 0, the transition is in the break and the transistor is faulty.
This technique is suitable exclusively for bipolar transistors. Therefore, before checking, you must make sure whether it does not include a composite or field device. Next you need to check between the emitter and the collector resistance. The closures should not be here.
If you need a transistor to assemble the electrical circuit, having an approximate current gain coefficient, using the tester you can determine the desired item. To do this, the tester is translated into HFE mode. The transistor is connected to the device that is suitable for a particular type of device, located on the device. The Multimeter screen should display the value of the H21 parameter.
How to check a thyristor multimeter? It is equipped with three P-N transitions than different from the bipolar transistor. Here the structures alternate among themselves on the manner of zebra. The main differences of it from the transistor is that the mode after entering the control pulse remains unchanged. Thyristor will remain open until the current in it falls to a certain value, which is called the deduction current. The use of a thyristor allows you to collect more economical electrical circuits.
The multimeter is set on the resistance measurement scale in the 2000 Ohm band. For the opening of a thyristor, the black probe joins the cathode, and the red to the anode. It should be remembered that a thyristor can be opened with a positive and negative impulse. Therefore, in both cases, the device resistance will be less than 1. The thyristor remains open if the control signal current exceeds the deduction threshold. If the current is less, then the key closes.
How to check the multimeter IGBT transistor
The bipolar transistor with an isolated shutter (IGBT) is a three-electrode power semiconductor device, in which two transistors in one structure are connected on the principle of cascade inclusion: field and bipolar. The first forms the control channel, and the second - power channel.
To check the transistor, the multimeter must be translated into semiconductors check mode. After that, with the help of probe, measure the resistance between the emitter and the shutter in the forward and reverse direction to detect the closure.
Now the red wire of the device is connected to the emitter, and black to touch the shutter briefly. There will be a shutter charge negative voltage, which will allow the transistor to remain closed.
Important! If the transistor is equipped with a built-in counter-parallel diode, which the anode is connected to the emitter of the transistor, and the cathode to the collector, then it must be signed accordingly.
Now you need to make sure the functionality of the transistor. First, it is worth charged with a positive voltage of the Emitter's inlet container. To this end, simultaneously and briefly red dipstick should be touched on the shutter, and black to the issuer. Now you need to check the emitter collector, connecting the black probe to the emitter, and the red to the collector. An insignificant voltage drop should be displayed on the multimeter screen of 0.5-1.5 V. This value has been stable for a few seconds. This suggests that there is no leakage in the input container.
Helpful advice! If the multimeter voltages are not enough to open the IGBT transistor, then for the charge of its input container, you can use a constant voltage source in 9-15 V.
How to check multimeter field transistor
Field transistors show high sensitivity to static electricity, so the grounding is required.
Before proceeding with checking the field transistor, it should be determined by its basement. On import devices, tags are usually applied, which determine the conclusions of the device. The letter S is denoted by the source of the device, the letter D corresponds to the drain, and the letter G is the shutter. If there is no baseback, then you need to use the documentation for the instrument.
Greetings to all lovers of electronics, and today in continuation of the topic Application of a digital multimeter I would like to tell how to check bipolar transistor using a multimeter.
The bipolar transistor is a semiconductor device that is designed to enhance the signals. Also, the transistor can work in key mode.
The transistor consists of two p-N transitions, and one of the conductivity areas is common. The average total conduction area is called the base, extreme emitter and collector. As a consequence, N-P-N and p-N-P transistors.
So, a schematic bipolar transistor can be represented as follows.
Figure 1. Schematic representation of the transistor A) N-P-N structure; b) P-N-P structure.
To simplify understanding p-N question Transitions can be represented as two diodes connected to each other with the same electrodes (depending on the type of transistor).
Figure 2. Presentation of the transistor N-P-N structure in the form of an equivalent of two diodes included with the anodes to each other.
Figure 3. Presentation of the transistor P-N-P structure in the form of an equivalent of two diodes included with cathodes to each other.
Of course, it is advisable for a better understanding. It is desirable to explore how the P-N transition works, and it is better how the transistor works in general. Here I will only say that in order to turn it on it through the P-n to turn it on in the forward direction, that is, on N - the area (for the diode it is a cathode) to submit minus, and on the P-region (anode).
I have shown you in video For the article "How to use a multimeter" when checking the semiconductor diode.
Since we presented the transistor in the form of two diodes, it is, therefore, it is necessary to simply check the health of these very "virtual" diodes to check it.
So, proceed to check the transistor n-P-N structures. Thus, the transistor base corresponds to the P- area, collector and emitter - N-regions. To begin with, we will transfer the multimeter to the mode of checking the diodes.
In this mode, the multimeter will show the voltage drop on the P-N transition in millivolts. The voltage drop on the P-N transition for silicon elements should be 0.6 volts, and for Germany - 0.2-0.3 volts.
First, we turn on the P-N transition transitions in the forward direction to be connected to the transistor database red (plus) the dipstream multimeter, and on the emitter the black (minus) Multimeter probe. At the same time, the indicator should highlight the voltage drop in the transition of the base-emitter.
It should be noted here that the voltage drop in the transition B-K. There will always be less than the voltage drop in the transition B-E.. This can be explained by the smaller transition resistance. B-K. Compared to the transition B-E.What is the consequence of the treatment area of \u200b\u200bthe collector has a large area compared to the emitter.
On this basis, it is possible to independently determine the base of the transistor, in the absence of a reference.
So, half of the case is done if the transitions are good, then you will see the voltage drop values \u200b\u200bon them.
Now it is necessary to enable P-N transitions in the opposite direction, while the multimeter should show "1", which corresponds to infinity.
Connect the black Property on the base of the transistor, red On the emitter, while the multimeter should show "1".
Now turn on in the opposite direction B-K.The result should be similar.
Left last check - Transition emitter collector. Connect red Probe multimeter to the issuer, the black To the collector, if the transitions are not punched, then the tester should show "1".
We change polarity ( red-collector, the black- Emitter) Result - "1".
If, as a result of the test, you will find no compliance with this technique, then this means that the transistor faulty.
This technique is suitable for checking only bipolar transistors. Before checking, make sure that the transistor is not field or composite. Many methods described above are trying to check exactly the composite transistors, besides them with bipolar (after all, on marking, you can not correctly identify the type of transistor), which is not the right solution. Correctly find out the type of transistor only by directory.
If there is no mode for checking diodes in your multimeter, you can check the transistor to switch the multimeter to the resistance measurement mode on the "2000" range. In this case, the test method remains unchanged, except that the multimeter will show p-N resistance transitions.
And now by tradition, an explanatory and complementary video for testing the transistor:
Content:
The performance of radio engineering schemes depends largely on the correct assembly, as well as test actions above its elements. Many radio amateurs independently collect schemes often arise: how to check the transistor multimeter, especially when it is already installed and the performance is being configured. collected device? In order to set up radio engineering schemes, you need to understand what is a transistor and how it works. Consider issues of testing the scheme and checking transistors.
Types of transistors
Checking the transistor for a specialist begins with the definition of an element according to its type, this action is performed in the case of repair work, as well as in the process of checking the acquired schemes for performance.
Semiconductor trigode, which is made of material with semis-contained properties, having three outputs, when it can control from a minor input signal in the circuit's circuit at the output of the circuit, is called a transistor. It is used in energy generation devices, in commuting circuits, in amplifying devices for amplifying electrical signals, as well as their conversion.
In radio engineering, there are two types of frequently occurring transistors - field and bipolar radio engineering elements.
Main types:
Bipolar transistors are characterized by creating an electrotock value at the outlet of electrons and holes, in other words, both carriers of signs. Field options are used to generate current at the output of the device, only one medium. With the help of a call at the multimeter, you can check the health of the bipolar element, which has three outputs and two P-n transitions. The operation of this element in the scheme provides for the use of electron charges and holes, through the control current is controlled through the transistor current. The bipolar transistor has semiconductor layers of N-P-N and P-N-P and two P-N transitions, layers are connected using the contacts: the middle layer is the base, two extreme layers are an emitter and a collector. In the radio engineering, the output with an arrow in the element in the diagram denotes the emitter and the direction of the flowing current.
Different transistors in type have different functions of charge carriers, more often found N-P-N Typeswho have best characteristics and parameters. Due to mobility, electrons play in the "first role" elements, the device's operation improves and with an increase in the collector transition area.
How to check the transistor multimeter
Specialists are offered step-by-step actionHow to check the performance of the radio engineering element:
- determine the structure of the semiconductor device by the emitter arrow;
- if the arrow shows the database, the transition is p-n-p;
- when the arrow is directed from the database of the device - N-P-N conduction.
Different types of conductivity:
After determining the conductivity of the diagram element, perform the following steps:
- we measure the presence of inverse resistance - the probe multimeter (+) we apply to the contact of the base;
- check the transition to the emitter - the probe of the device (-) we apply to the emitter contact.
The result of these manipulations will be value \u003d 1, when the element is operational, then check the direct resistance:
- the probe multimeter (-) is transferred from the emitter to the base;
- positive probe (+) take turns apply to the collector and the issuer.
In the working transistor, the multimeter with these manipulations should show resistance from 500 to 1000 ohms, which indicates the integrity of the component.
When a question arises, as a multimeter to check the transistor, specialists offer radio amateurs to determine the base, as it is often difficult to be difficult to determine. To do this, you must perform the following actions:
- black (-) probe connect to the first contact, and the plus to the second;
- then measured - black on the first contact (+) on the third contact;
- when the voltage on the display drops, it means that a pair of "Emitter - base" or "collector - base" is defined;
- the next step we determine the second pair, and the general contact is the base.
How can you make sure the performance of the transistor in the scheme?
Each time it is difficult to check the operation of the elements, applying the supply of them from the scheme, it is difficult, in some cases it is difficult to do, for this reason, experts recommend using a probe that will help check the self-functioning of the transistor.
This device is a block generator, checking the NPN of the transistor - this is the execution of the active device task, the indicators in the complex scheme are shown, breaks through the semiconductor device or not. There are many solutions for the manufacture of probes, their options are well presented on the network. To ring the triode, step by step need to make the following actions:
- Check the work of the probe on a working transistor, there must be generation, then continue to test the probe. If there is no generation, it is necessary to change the conclusions of the windings by places.
- We pay attention to L1, a lamp that works on the opening of the probe, it should be lit if the lamp does not respond, we try to change the conclusions on the transformer windings.
- When the probe is checked, start working with the scheme - check the PNP transistor in the diagram without dropping on the board, connect the probe to the outputs, and the transition switch is set to one of the modes - P-N-P or N-P-N, we turn on the power.
When L1 is lit, this means that the element is operational if L2 lights up, then this is a certificate of some kind of malfunction, perhaps one of the transitions. If the L1 does not burn, nor L2, this means that the semiconductor device does not work.
When it is not possible to check the transistor to a multimeter, you should not despair, there are probes that do not require preliminary adjustment, they have more simple scheme - This is an ordinary battery and a light bulb, you can use the LED. When an alternate touch of transistor contacts simple device The pair is determined in which the LED lights up, and in another embodiment there is no - element of radio engineering (transistor) working. This method is recommended to nick the circuit on the boards, where there is no power current. You can check the tester.
For what reason the transistor does not work
Most probable reasonsAccording to experts, the failure of the trigger in the scheme is as follows:
- when it disappears (breaks) one of the transitions;
- transition breakdown;
- breakdown on one of the sections of the emitter or manifold;
- power loss by a semiconductor device in work;
- visual damage to the conveyor conclusions.
Signs for which you can define a visually breakdown of the trigger in the scheme: a darkening or change in the original color of the semiconductor device, the change in its form "bulge", the presence of a black spot.
How the composite transistor is checked
The Darlington device is called a composite transistor, which in its scheme to combine several bipolar semiconductor devices, which allows the scheme to solve such tasks such as a double or greater increase in current. Usually, composite transistors are used in the schemes in which high current flows: stabilizers, power amplifiers. In these devices need high level Input impedance, in other words, complex resistance in full. Check the composite transistor can be in the same way as N-P-N Element - device multimeter, as an ordinary bipolar device.
Output
Before dealing in the question, how to test the serviceability of the trigger, it is necessary, according to experts, to understand how it is arranged and how it should work. The next step is recommended to accommodately approach the choice of the technique of testing the performance of the transistor multimeter. In addition to the definition of a faulty element in the scheme, it is necessary to understand the reason for the appearance of this malfunction, to replace little transistor, it is necessary to eradicate the reason that led it into a non-working condition.
Let's take care of theory, having to run away. Portal Your equipment Along with zaulnye maxims, calculated to be understood by the pro, will provide the method of five fingers. Did not hear? Just like five fingers. First discuss the types of transistors, then we will tell you what can be done using a multimeter. Consider regular HFE sockets (explain what it is), the method of replacing the scheme through a connection of several diodes. Tell me where to start. You will understand how to check the transistor multimeter, or ... Let's perhaps without "or". Let's proceed to firmly distinguish the MOS transistor from the pug, the theory is popula.
Types, classification of transistors
We avoid explore the debris. Know a simple rule: in bipolar transistorx Media of both signs are involved in creating an output current, in the field - one. Definition of moghers. Now we work with your fingers:
- Field type transistors perform the beginning. When the Beatles went on stage, semiconductors began to come to replace vacuum triggers. If we say briefly, the P-N-P transistor is two rich in positive carriers of the crystal layer (silicon, germanium, impurity conductivity). Conducting physics lessons, the teacher often told how V-valence arsenic doped with a silicon grille, forming new material. We add that positive P-areas, fencepred off narrow negative (N-Negative). How com in the throat. The narrowstone, called the base, refuses to let the electrons (in our case, is more like a hole) to flow in the desired direction. A small negative charge appears on the control electrode, the manifold holes (the top P-area on the traditional electrical circuits) You can no longer hold back, literally rush towards the applied voltage. Since the base is thin using the variable speed, the carriers fly over, are carried out further - reaching the emitter (lower p-area), here are enjoyed by the difference in potentials created by the supply voltage. Typical school explanation. The relatively small voltage of the control electrode is capable of adjusting the speed of the strong thread of holes (positive media), which is fascinated by the supply voltage field. This built the equipment. Electrons are moving towards holes, transistors are called bipolar.
- Field transistors are equipped with a channel of any type of conductivity separating the source and drain areas (see the figure above). The control electrode is called a shutter. Moreover, the main material of the substrate, the shutter is opposite to the channel, source and drain. Therefore, the positive voltage (see Figure) Ban the move charges through the transistor. Plus will delay the electrons available (in P-region). Field transistors in electronics are used much more often. In the figure, the shutter is electrically connected to the crystal, the structure is called the control of the P-N transition. It happens, the region is isolated from a dielectric crystal, which often performs oxide. Pure Water Mosfet Transistor, in Russian - MOS.
Using a multimeter, bipolar transistors are checked in normal mode. If the tester supports such an option, often called HFE, a round connector is mounted on the front panel, divided by a vertical line into two parts, where 4 sockets are written as follows:
- B - base (eng. Base).
- C - collector (eng. Collector).
- E - Emitter (Eng. Emitter).
Emitter nests are two to take into account the layout of the body conclusions. The base can be from the edge, in the middle. For convenience done. There is no difference, which nest insert the leg of the emitter of the bipolar transistor. Couple words how to use.
Check bipolar transistor multimeter in normal mode
To check the bipolar transistors checks to work (measure measurements), we will transfer the tester to the HFE mode. Where did the letters come from? h - concerns the category of parameters describing the four-pole of any type. It does not matter to know what implies the concept - just understand: exists whole group H-parameters, among which there is one important electronics. Called the current gain with a common emitter. Denotes, H21 (or the lowercase Greek letter beta).
Digital mnemonics is poorly perceived by a human eye, so it was decided (abroad, a clear case) that f will mean direct amplification The current (Forward Current Amplification), whereas E says that the measurement was conducted in a circuit with a common emitter (which is used by textbooks of physics to illustrate the principles of operation of bipolar type transistors). There are many inclusion schemes, each has advantages, parameters can be described through H21 (some others mentioned by references). It is believed if the gain is normal, 100% is operational radio element. Now readers know how the P-N-P transistor or N-P-N transistor is checked.
h21 depends on some parameters specified by the manual of the multimeter. 2.8 V power supply voltage, 10 mA database current. Further the graphics of technical documentation (Data Sheet) of the transistor, the professional knows how to find the rest. When the HFE mode is turned on, connecting the legs of a bipolar transistor to the desired jacks on the display, the value of the gain of the current instrument appears. Break down to compare the reference data by making an amendment to the measurement mode (if necessary). Just sounds difficult, just a couple of times to do yourself, will achieve results.
Checking transistors Multimeter: Non-standard mode
Suppose, causes doubt the health of the field type transistor. Famous Russian question in electronics is present. Start thinking ... M-yes.
- The field transistor unlocks or locked up by a certain voltage mark. Discussed above. If you remember, they spoke, when the tester arrows a small tester constant pressure. We will use in our tests. While the transistor on the board is difficult to make measurements, it is worth removing from the usual environment how non-standard techniques can be applied. It turns out that if applied to the electrode unscrewing voltage, due to some of its own capacity of the transistor, the region will charge, keeping acquired properties. It is allowed to ring the electrodes between the source and the drain. The resistance of the order of 0.5 com will show: the field transistor is operational. It is worthwheling the base with other discharges, the conductivity will disappear. The field transistor closed and suitable.
- Bipolar transistors, the field with the control P-N transition check much easier. In the first case, the diagram of replacement of the element with two diodes included towards meet (or vice versa backs) is applied. Let's give unlocking voltage (P - plus, n - minus), obtaining a nominal 500 - 700 Ohm at the resistance meter. You can also call, using hearing. No wonder the diode is often drawn on the scale. The transversion is used to verify performance. Voltages enough to open the P-N-transition.
Preparation for testing transistor
At times grab the composite transistor. There are several keys inside the case. It is used to save space while simultaneously increasing the gain (and in tens, thousands of times, if it came about a cascade scheme). The transistor of Darlington is arranged. Protective stabilion will be sewn into the body, protecting the emitter-base transition from voltage overload. Testing is in one way:
- Need to find detailed specifications transistor (composite element). With the current scale of the computerization will not make problems. Even if the product is imported. Designations on the schemes are clear, the terms are not complex. The HFE parameter has painted.
- Then the study is carried out, analysis is performed. Fractionment of the scheme for simpler components. If a stabilion is turned on between the manifold and emitter transitions, it is logical to start checking from it. In the initial moment, the transistor is locked, a multimeter current will go, bypassing a protective cascade. In one direction, Stabilitron will give the resistance of 500-700 ohms, in the other (if not breaking) will be a break. Similarly, we break into the part of the Darlington transistor, if you have a view (discussed above).
The transverse mode will show the numbers. They say the voltage drop, according to some information, the random of resistance. Throwing to lead the experiences, solving the question. Call the known resistance, obviously a good resistor. If the nominal nominal appears on the screen, there is nothing to think. Otherwise, you can estimate the current (separating the display potential on the denomination). To know too, it is necessary to know in the process of testing. Before the start of work, it is recommended to preach to explore the multimeter. Remove the instructions from the trash can, read.
The people are interested in the question whether it is possible to check the transistor with a multimeter without falling down. Obviously, much determined by the scheme. The tester simply applies voltages, evaluates emerging currents. Based on the testimony, the gain coefficient is calculated, serve as a criterion of suitability / dissent. Try checking the field transistor by a multimeter from the processor that are part of the processor! Throw the hope of everyone here is incoming. You can not always ring the field transistor multimeter.
Bipolar transistor to diodes
The figure, presented among the text, demonstrates the transistor substitution scheme with two diodes. Let us consider the enhancement element by presenting the sum of two independent simpler. Not possessing the gain exhibiting nonlinear properties (integrity of direct / reverse inclusion).
Powerful power circuits transistors are powerless to open the meantime forces. Therefore, special schemes apply to testing devices. You can not check the bipolar transistor multimeter directly.
Verification of conditional diodes replacing the transistor
Methods are several. You can try to measure the resistance to the standard scale Ω. Red dipstick need to apply to the p-area. Then the multimeter display will show a digit, less infinity. In the opposite direction, the result will be zero. Multimeter will show a break. Normal diode transverse results.
If you enjoy a special mode, the screen shows the resistance size in the forward direction, the break (standard one in the left corner of the LCD screen) in another. Note - the drawing contains explanatory inscriptions where to lean the probe to get open P-N transition. In the opposite direction, the device shows a break.
Such semiconductor elements like transistors are an integral part of almost all electronic circuits - from radio receivers to system Plasteps Ultrasound computing centers. Checking this element for performance - the operation that is obliged to be able to perform any person, one way or another engaged in the repair of electronic circuit, be it a professional repairman or an amateur.
To carry out this operation, you can apply a special tester of transistors, but if it is not at hand, or in its reliability there are doubts, you can use the most ordinary multimeter. Even those models that do not have a special jack for checking bipolar or field transistors can be used to accurately check. For this, the multimeter is set to the maximum resistance mode, or "transverse", if there is one.
General verification algorithm
How to check the transistor multimeter? In general, the algorithm looks like this:
Further verification steps will depend on what type item is required to check. Basically, semiconductor elements of two species are used in electronics - bipolar and field.
Bipolar
How to check the bipolar transistor multimeter? First of all, it is necessary to find out to which of the two subtypes - NPN or PNP it applies. To do this, let's remember that there is a bipolar transistor at all.
This is a semiconductor element in which the so-called NPN or PNP transition is implemented. N-P-N is the transition "Electron - hole - electron", P-N-P, respectively, on the contrary, "hole - electron-hole". Structurally, it consists of three parts - emitter, manifold and bases. In fact, the bipolar star is two conjugate ordinary diode, in which the base is a common point of connection.
In the PNP scheme, the transistor differs from its NPN-collected direction of the arrow in the circle - arrow of the emitter transition. W. p-N-P Schemes It is directed to the database, N-P-N is the opposite.
This difference you need to know to check the bipolar transistor. The PNP scheme opens by an app to the negative stress base, NPN is positive. But before that, it is necessary to find out which of the contacts of the test transistor is the base, which emitter, and which collector.
Please note that it is possible to determine the method described below which of the contacts is the base, and which is an emitter and a collector, you can only have a working element. By itself, the fact of passing the transistor of this check indicates that it is most likely in good condition.
The instruction here may be as follows:
- the red (positive) probe is connected to the first conclusion, for example, the left, black (minus) alternately relate to the central and right. Fix the value "1" on the central, and 816 ohms, for example, on the right;
- the red multimeter probe shout with central contact, black - alternately with side. The device issues "1" on the left and any value, for example, 807 is on the right;
- upon contact of the red probe multimeter with the right conclusion, and the black - with the left and central, we obtain in both cases "1". This means that the base is defined - this is the right contact of the transistor. And the transistor itself is PNP-type.
In principle, this is enough to say that the transistor is working. Now, in order to check its structure and the specific arrangement of the emitter and the collector, turn black (minus) the diploma of the multimeter with the base, and the red - in turn with the left and central contact.
That contact that gives a smaller resistance value, will be collector (in our case 807 ohms). The one that is 816 ohms is an emitter.
Checking the type transistor NPN occurs the same way only to the database is applied by the plus contact.
This is a way p-N checks transitions between the base and collector and the base and the emitter. Multimeter readings can be different, depending on the type of transistor, but will always lie within 500-1200 ohms. To complete the test, tap the emitter and manifold. A good element will extract infinitely large resistance regardless of its type, no matter how you change polarity. If the value on the screen differs from "1" - one of the transitions is broken, the part is unsuitable for operation.
Check without falling
If you do not have confidence that it is necessary to check this transistor, it is possible to measure its parameters on the board without paying. But at the same time the multimeter should show values \u200b\u200bwithin 500-1200 ohms. If they are measured by units or even dozens of OM - the scheme is hosted by low-voltage resistors. To accurately check the transistor will have to fall.
Field
Field, it is also a MOSFET transistor differs from bipolar in that it can occur or only a positive charge or only negative ("hole" or electron). His contacts are different - shutter, stock, source.
How to check the field transistor multimeter? The test method is almost the same as in the previous case, but before, in order to avoid the output of the element, it is necessary to remove the charge of static electricity, since the pool is very sensitive to the statics. Use an antistatic bracelet or simply tap the headed metal element, such as the instrument cabinet housing.
Wilders always have a small conductivity between the drain and the source, which is detected on the multimeter screen as the resistance of about 400-700 ohms. If polarity change, resistance will change slightly, it will increase or fall at 40-60 ohms. Before that, it is necessary to navigate the source and the flow of each other to "reset" the transition tanks.
If when checking with a multimeter between the source and the runa, the infinitely large resistance is detected, the field transistor is faulty.
Between the source and the shutter or the drain and the shutter will also be detected by conductivity, but only one way. Plus, attached to the shutter, and minus - to source, will cause the opening of the transition and, accordingly, the value on the screen within 400-700 ohms. The reverse scheme is plus to source, minus to the shutter - the serviceable field will give "1", that is. Very big resistance.
Check line Stoke-shutter is similar. If the line of the source-shutter or the stock shutter has a conductivity in both directions, this means that the field transistor is broken.
In conclusion, you must say a few words about the composite type. The composite transistor is an element connecting two ordinary bipolar transistors (sometimes three or more). Checking the multimeter is made similarly to the methodology for a simple "bipolar".