Most thyristors can be tested with a light bulb and a constant voltage that can light it up.
We supply plus to the anode, and connect the light bulb (minus) to the thyristor cathode (see figure). Having briefly connected the anode and the control output, we open the thyristor. Even after disconnection, the light should be on.
Testing a thyristor with a tester |
To test the thyristor, in most cases, the energy of one and a half volt power supply of the mini-tester in the "xl kOhm" mode is sufficient. When briefly touching the control output with a probe connected to the anode (see figure), the arrow should deviate. The return of the arrow (after removing the probe from the control output) indicates that the thyristor has lost the ability to hold the open state. If the test fails, swap the probes (for some devices, switching to the "xl kOhm" mode reverses the polarity).
This circuit is also intended for testing thyristors KU101, KU202 and others. It works as follows, if a voltage is applied between the anode and cathode of the thyristor, then to open it, a positive voltage must be applied to the control electrode. Thus, current flows in the "control electrode - cathode" chain and the thyristor opens. If the current flowing through the thyristor is less than the holding current of this instance of the thyristor, then when the voltage is removed from the control electrode, the thyristor closes. If the current exceeds the holding current, the thyristor remains open. The tested thyristor VS1 is connected in accordance with the figure.
We will consider the thyristor to be fully operational if, after the first connection, the LED does not light, and when the button is pressed, it lights up. When the button is released, the LED may or may not light up. If the LED lights up before the button is pressed or does not light up after it is pressed, then the thyristor is faulty.
Dear radio amateurs, I propose to your court another version of the circuit for checking the thyristor's health. If the LED is on when the power is turned on, then press the button and then release it. If the LED goes out, then the thyristor is turned off. If the thyristor does not turn off, then it is faulty. We press the button again, the thyristor opens. The burning of the LED in this case indicates the serviceability of the thyristor.
Resistor R4 must be connected directly to contacts X1 in order to exclude the effect of interference on the wires
R1 limits the starting current
R2 serves to discharge C1 with a resistance of 3-10 kOhm
How to check thyristor and triac |
We already know how to check the thyristor, but what should we do if it becomes necessary to check the triac. Yes, everything is very simple, we modernize the probe already known to us a little. The result is such a universal device for testing not only triacs, but also thyristors.
25.06.2018
Various elements are used for switching AC electrical networks. Most often, powerful triacs are used, which are necessary for the design of transformers and chargers.
Triacs are a type of thyristors, which are analogues of silicon rectifiers in a case. But, unlike thyristors, which are unidirectional devices, that is, they transmit current in only one direction, triacs are two-way. With their help, you can transfer current in both directions. They have five thyristor layers, which are equipped with electrodes. At first glance, domestic triacs resemble the p-n-p structure, but they have several regions with n-type conductivity. The last area, which is located after this layer, has a direct connection with the electrode, which ensures high signal conductivity. Sometimes they are also compared to rectifiers, but it is worth remembering that diodes transmit an electrical signal in only one direction.
Photo - use of a thyristor
The triac is considered an ideal device for use in switching networks, as it can control the current flowing through both halves of the alternating cycle. The thyristor controls only a half cycle, while the second half of the signal is not used. Due to this feature of work, the triac perfectly transmits the signals of any electrical devices, a triac is often used instead of a relay. But at the same time, the triac is rarely used in complex electrical devices, such as transformers, computers, etc.
Photo - triac
Video: how the triac works
The principle of operation of a triac is very similar to a thyristor, but it is easier to understand it based on the operation of the trinistor analogue of that component of electrical networks. Note that the fourth semiconductor component is separated, allowing the following functions:
In this case, the operation of the device can be regarded as a combination of two oppositely directed thyristors, but operating in a full cycle, i.e., not breaking the signals. The marking on the diagram corresponds to two connected thyristors:
Photo - trinistor analogue of triac
According to the drawing, a signal is transmitted to the electrode, which is the control one, allowing the contact of the part to be opened. At the moment when the anode voltage is positive, respectively, the cathode is negative - the electric current will begin to flow through the trinistor, which is on the left side of the diagram. Based on this, if you completely change the polarity, which will swap the charges of the cathode and anode, the current transmitted through the contacts will go through the right trinistor.
Here the last layer on the triac is responsible for the polarity of the voltage. It controls the voltage on the contacts and comparing it, redirects the current to a specific trinistor. Directly proportional to this, if the signal is not applied, then all the SCRs are closed and the device does not work, i.e., does not transmit any pulses.
If there is a signal, there is a connection to the network and the current must flow somewhere, then the triac conducts it in any case, the polarity of the direction in this case is dictated by the charge and polarity of the poles, cathode and anode.
Please note that the diagram above shows the current-voltage characteristic (CVC) of the triac, in Figure 3. Each of the curves has a parallel direction, but in the other direction. They repeat each other at an angle of 180 degrees. Such a graph allows us to say that a triac is an analogue of a dinistor, but at the same time, areas through which dinistors do not transmit a signal are very easily overcome. The parameters of the device can be adjusted by applying a current of different voltages, this will allow you to unlock the contacts in the right direction, simply by changing the polarity of the signal. In the drawing, places that can change are marked with dashed lines.
Photo - triacs
Thanks to this CVC, it becomes clear why the stabilized thyristor received such a name. Triac - means "symmetrical" thyristor, in some textbooks and stores it may be called a triac (foreign version).
The bidirectionality makes triacs very useful switches for AC circuits, allowing them to control large flows of electrical energy passing through small contact poles. In addition, even the percentage of inductive load current can be controlled.
Photo - triac work
The devices are used in radio engineering, electromechanics, mechanics and other industries where it may be necessary to control the current flow. Optotriacs are often used in alarm systems and dimmers, where a full cycle, rather than a half cycle, is required for the correct operation of devices. Although quite often the use of this radio component is not effective. For example, to operate a small microcontroller or transformer, it is sometimes better to connect low-power thyristors, which will ensure the operation of both periods equally.
In order to use the device in operation, you need to know how to check the triac with a multimeter or “ring” it. For verification, you need to evaluate the characteristics of controlled silicon diodes. Such rectifiers allow you to set the desired readings and conduct tests. The negative terminal of the ohmmeter is connected to the cathode, and the positive terminal is connected to the anode. After that, you need to set the indicator on the ohmmeter to one, and connect the control electrode to the anode output. If the data is between 15 and 50 ohms, then the part is working fine.
Photo - light control by triacs
But at the same time, when you disconnect the contacts from the anode, the ohmmeter readings should be saved on the device. Make sure that a simple measuring device does not show residual resistance, otherwise it will indicate that the part is not working.
In everyday life, triacs are often used to create devices that extend the life of various devices. For example, for incandescent lamps or meters, you can make a power regulator (you will need a MAC97A8 thyristor or TC).
Photo - scheme of the power regulator on the triac
The diagram shows how to assemble a power regulator. Pay attention to the elements DD1.1.DD1.3, where the generator is indicated, due to this part, about 5 pulses are produced, which are half-cycles of one signal. The pulses are controlled by resistors, and a transistor with rectifying diodes controls the moment the triac is turned on.
Photo - triac measurement
This transistor is open, based on this, a signal is applied to the input of the generator while the triacs and the remaining transistors are closed. But if at the moment of opening the contacts the state of the generator does not change, then a small impulse will be generated by the storage elements in order to start the pinout. Such a dimmer circuit on a triac can be used to control the operation of lighting devices, a washing machine, the speed of a vacuum cleaner or incandescent lamps with a motion sensor. Use a tester to check the operation of the circuit and you can use it.
Photo - triac work
To improve the system, it is possible to arrange the control of the triac through an optocoupler so that the element is switched on only after the signal. Please note that if, when scrolling the drum, movements occur very sharply, then the electronic module is faulty. Most often, the triac burns out, imported conductors often do not withstand voltage surges. To replace it, simply select the same part.
Photo - thyristor charger
Similarly, according to the scheme, you can assemble a charger on a triac, depending on the requirements, you just need to buy low-power or power parts KU208G, KR1182PM1, Z0607, BT136, BT139 (BTB - VTV, BTA - VTA are also suitable). In domestic import conditions, foreign triacs are used, the prices of which are slightly higher.
To check the radio elements for operability, a multimeter is most often used. It is good because with its help, you can quickly identify radical defects in most radio components. The downside here is that not every multimeter, and not every detail, can be tested thoroughly.
Most often called a tester, less often - an avometer (Amp-Volt-Ohm-meter) and, almost never, directly a multimeter. Consists of a precision pointer potentiometer head and complex switched measurement circuits. Moreover, the internal battery (4.5-9 V.) is needed only for measuring resistance. Voltage and current can be measured without it.
You can check the thyristor with a multimeter of such a plan only if you have a fresh, not discharged battery.
So they call it, less often - a tester, and, almost never - an avometer. Consists of simplified switched measurement circuits serving a microcontroller with an ADC (analogue-to-digital converter). Its wide measuring range, sensitivity and accuracy make it possible to do without them. The internal battery (1-9 V) is used not only to measure resistance, but also to power the microcontroller and its peripherals.
Consider the sequence of actions to determine the performance of the thyristor.
Now let's try to check the thyristor for opening, its main work. To do this, we apply the negative probe to the cathode, the positive probe to the anode and, without taking it off the anode, briefly touch the control electrode. The thyristor should open (resistance drops to almost 0 ohms) and be held in this state until the circuit breaks.
If this didn't happen then:
Before throwing away the thyristor, let's check the multimeter and the correctness of our actions when working with it:
Digital toy testers, the size of a matchbox and powered by a watch battery, are not suitable for testing semiconductor elements. Yes, and rely on their other measurements is not worth it. But it is also wrong to say that it is impossible to check the thyristor with a digital multimeter (and there is such an opinion). It is possible, and very many. Compliance with the above rules, allows you to achieve positive results with different devices.
Trinistor- This is a special type of semiconductor, which belongs to a subclass of thyristors and to the class of diodes. It is a diode, but this "diode" also has a third terminal, called Control Electrode(UE). It turns out that a trinistor is a diode with three leads :-). Trinistors are also called by the type of subclass - thyristors - and there is no mistake in this, so in this article I will simply call them thyristors.
They look something like this:
And here is the circuit designation of the thyristor
The principle of operation of the thyristor is based on the principle of operation of the relay. A relay is an electromechanical product, while a thyristor is purely electrical. Let's look at the principle of operation of the thyristor, otherwise how can we check it then? I think everyone rode the elevator ;-). By pressing the button on any floor, the elevator electric motor starts its movement, pulls a cable with a cabin with you and your neighbor Aunt Valya about two hundred kilograms, and you move from floor to floor. How, with the help of a tiny button, did we raise the cabin with Aunt Valya on board? In this example, the principle of operation of the thyristor is based. By controlling a small voltage of a button, we control a large voltage... isn't that a miracle? Moreover, in the thyristor there are no clattering contacts, as in a relay. This means that there is nothing to burn out there and, under normal operation, such a thyristor will serve you, one might say, indefinitely.
Currently, powerful thyristors are used for switching (switching) high voltages in electric drives, in metal melting installations using an electric arc (in short, using a short circuit, resulting in such powerful heating that the metal even begins to melt)
SCRs, which are on the left, are installed on aluminum radiators, and tablet SCRs are even installed on water-cooled radiators, because a frantic current passes through them and they switch very high power.
Low-power SCRs are used in the radio industry and, of course, in amateur radio.
Let's look at some important parameters of thyristors. Without knowing these parameters, we will not catch up with the principle of testing the thyristor. So:
1) U y- - the smallest constant voltage on the control electrode, causing the trinistor to switch from a closed state to an open one. In short, in simple terms, the minimum voltage on the control electrode, which opens the trinistor and the electric current begins to flow calmly through the two remaining outputs - the anode and cathode of the trinistor. This is the minimum opening voltage of the trinistor.
2)U arr max - reverse voltage, which the thyristor can withstand when, roughly speaking, plus is applied to the cathode, and minus to the anode.
3) I os wed -average current, which can flow through the trinistor in the forward direction without harm to its health.
The remaining parameters are not so critical for beginner radio amateurs. You can find them in any reference book.
Well, finally, let's move on to the most important thing - checking the trinistor. We will check the most popular and famous Soviet trinistor - KU202N.
And here is his plinth
To test the trinistor, we need a light bulb, three wires and a DC power supply. On the power supply, set the voltage for the light bulb to turn on. We tie and solder the wiring to each output of the trinistor.
We supply a "plus" from the power supply to the anode, and a "minus" to the cathode through a light bulb.
Now we need to apply voltage relative to the anode to the Control Electrode (UE). For this type of trinistor U y- triggering DC control voltage more than 0.2 volts. We take a one and a half volt battery and apply voltage to the UE. Voila! The light bulb is on!
you can also use the multimeter probes in the continuity mode, the voltage on the probes is also more than 0.2 Volts
We remove the battery or probes, the light should continue to burn.
We opened the thyristor by applying a voltage pulse to the RE. Everything is elementary and simple! In order for the thyristor to close again, we need to either break the circuit, that is, turn off the light bulb or remove the probes, or apply a reverse voltage for a moment.
You can also check the thyristor with a multimeter. To do this, we collect it according to this scheme:
Since there is voltage on the probes of the cartoon in the continuity mode, we apply it to the UE. To do this, we close the anode and RE between ourselves and the resistance through the anode-cathode of the thyristor drops sharply. On the cartoon we see 112 millivolts of voltage drop. This means that it has opened.
After releasing, the cartoon again shows an infinitely large resistance.
Why did the thyristor close? After all, the light bulb in the previous example was on? The thing is that the thyristor closes when the holding current becomes very small. In the multimeter, the current through the probes is very small, therefore the thyristor closed without voltage RE. There is also a diagram of an excellent thyristor test device, you can look at it in this article.
I also advise you to watch the video from ChipDip about checking the thyristor and holding current:
Any electrical appliances and electrical boards are based on a complex of various radio elements, which are the basis for the normal functioning of the whole variety of electrical engineering. One of the main elements of any electrical circuit is a triac, which is one of the types of thyristor.
Speaking of a thyristor, we will also mean a triac. Its purpose is to switch the load in the AC network. Internal organization includes three electrodes for the transmission of electric current: control and 2 power.
A feature of the thyristor is the passage of current from one contact (anode) to another (cathode) and in the opposite direction. Any thyristor is controlled by both positive and negative current. For its operation, a low-voltage pulse must be applied to the control contact. After such a signal supply, the triac opens and goes from a closed state to an open one, passing a current through itself. During the passage of the triggering current through the control contact, it opens. And also unlocking occurs when the voltage between the electrodes exceeds a certain value.
When alternating current is applied, the change in the state of the thyristor causes a polarity reversal voltage on the power electrodes. It closes when the polarity is reversed between the power terminals, and also when the operating current is lower than the holding current. To prevent false triggering of the triac, caused by various radio-mechanical interference, the devices used have additional protection. To do this, a damper RC circuit is usually used (a series connection of a resistor and a DC capacitor) between the power contacts of the triac. Sometimes an inductor is used. It serves to limit the rate of change of current during switching.
If we talk about triacs, it is necessary to take into account the fact that this is one of the types of thyristor, which also has three or more p - n transitions. Their difference is only in the control cathode, which determines the corresponding transient characteristics of the transmitted current and, in principle, work in electrical circuits. Usually they begin their work immediately after starting the supply voltage to the desired contact.
The thyristor control circuit is simple and reliable. They are much simplify the concept with its presence, freeing it from unnecessary electrical components and tracks. Thus, facilitating further repairs (checking and dialing) in case of need or failure of radio-electronic units with their participation.
Necessary knowledge for checking, replacing and subsequent repair of various radio-electronic units involving triacs or thyristors help any radio amateur to improve their professional and practical skills.
In electronic circuits of various devices, semiconductor devices - triacs are often used. They are used, as a rule, when assembling regulator circuits. In the event of a malfunction of an electrical appliance, it may be necessary to check the triac. How to do it?
In the process of repairing or assembling a new circuit, it is impossible to do without electrical parts. One of these parts is a triac. It is used in circuits of signaling devices, light controllers, radio devices and many branches of technology. Sometimes it is used again after the dismantling of non-working circuits, and it is not uncommon to encounter an element with a marking that has been lost from long-term use or storage. It happens that new parts need to be checked.
How can you be sure that the triac installed in the circuit is really working, and in the future it will not be necessary to spend a lot of time debugging the assembled system?
To do this, you need to know how to check the triac with a multimeter or tester. But first you need to understand what this part is and how it works in electrical circuits.
In fact, a triac is a type of thyristor. The name is made up of these two words - "symmetrical" and "thyristor".
Thyristors are usually called a group of semiconductor devices (triodes) that can pass or not pass electric current in a given mode and at certain intervals. This creates the conditions for the operation of the circuit in accordance with its functions.
Thyristors belong to the class of diodes. But in addition to the anode and cathode, thyristors have a third output - a control electrode.
A thyristor is a kind of electronic switch, consisting of four layers, which can be in two states:
Thyristors have high power, due to which they switch the circuit at a voltage of up to 5 thousand volts and with a current of 5 thousand amperes. Such switches are capable of conducting current only in the forward direction, and in a state of low conductivity, they are able to withstand even reverse voltage.
To adventure between states, a special technology is used that transmits signals. With the help of a signal from the control object, the thyristor will become in the high conductivity (open) position, and in order to turn it off, you need to connect the charged capacitor to the key.
There are different thyristors that differ from each other in characteristics, control, etc.
The most famous device data types:
The use of thyristors is very wide, ranging from car chargers to generators and transformers.
The general application is divided into four groups:
Prices for devices are different, it all depends on the brand of the manufacturer and technical characteristics. Domestic manufacturers make excellent thyristors at a low cost. One of the most common domestic thyristors, these are devices of the KU 202e series, are used in household appliances.
Here are some characteristics of this thyristor:
Sometimes there are situations in which it is necessary to check the thyristor for performance. There are various verification methods, this article will cover the main ones.
For this method, it is enough to have on hand only a light bulb, a battery, 3 wires and to solder the wires to the electrodes. This set can be found in everyone's home.
When checking the device using the battery and bulb method, you need to estimate the hundred mA current load that the bulb creates on the internal circuit. The load should be applied for a short time. When using this method, a short circuit rarely occurs, but to be one hundred percent sure that it definitely will not happen, it is enough to pass the current through all pairs of thyristor electrodes in both directions.
Testing by the light bulb and battery method is carried out according to three schemes:
So the health of the thyristor is easy to check at home, without special equipment at hand. If the circuit is broken through the anode or cathode, the thyristor will activate a low conductivity state.
When using this method, a short circuit rarely occurs, but to be one hundred percent sure that it definitely will not happen, it is enough to pass the current through all pairs of thyristor electrodes in both directions This is the easiest option to check. In this method, the anode and contacts of the RE are connected to a measuring device (). The role of a constant current source is played by the batteries of the multimeter. As an indicator - arrows or digital indicators.
What you need to check the thyristor with a multimeter:
To check the thyristor without soldering, you need to disconnect the RE from the chain circuit. Next, you need to do all the points that are described above.
The role of a constant current source is played by multimeter batteries, as an indicator - arrows or digital indicators Also, the thyristor can be checked with a tester. To do this, you need a tester, a battery of six to ten volts and wiring.
To check the device with a tester, you need to follow the following scheme:
Another thyristor can be checked with an ohmmeter. This method is similar to checking with a multimeter and tester. Required:
That's basically all the instructions for checking. If after these steps you disconnect the RE from the anode, but do not break the connection between the anode and the ohmmeter, the device sensor should show low resistance (this occurs if the anode current is greater than the holding current).
There is also another way to check the thyristor using ohmmeters, for this you will need an additional ohmmeter. It is necessary to connect the positive output of one ohmmeter to the anode, the resistance at this moment should show high. Then follows, also a positive output, but of another ohmmeter, quickly connect and disconnect from the control electrode (UE), at this moment the resistance of the first ohmmeter will decrease sharply.
Thyristor protection:
Thyristors act on the rate of increase in direct current. Thyristors have reverse recovery current. If this current falls to a lower value, an overvoltage may occur. To prevent overvoltages, CFTP circuits are used. Varistors are also used for protection, they are connected to places where there are inductive load leads.
A thyristor is a semiconductor device of p-n-p-n structure, which plays the role of a key in circuits with high currents, while it is controlled by a low-current signal. It is applied to inclusion of power electric drives, systems of excitation of generators. Switched currents reach up to 10 kA. The peculiarity of thyristors is that when a control signal is applied, they open and remain in this state, even if the signal is subsequently removed. The only requirement is that the current flowing through them must exceed a certain value, which is called the holding current.
Some thyristors pass current only in one direction. These are dinistors that are triggered by exceeding a significant voltage. There are also trinistors controlled by applying current to the third output of the device. Thyristors that pass current in both directions are called triacs or triacs. In addition, there are light-controlled photothyristors.
To check the trinistor, you need to know and understand what is hidden behind the main parameters and why they need to be measured.
The triggering control voltage Uy is a constant potential at the control electrode, which causes the thyristor to open.
Uobr max is the maximum reverse voltage at which the thyristor is still in operation.
Ioc cf is the average value of the current flowing through the thyristor in the forward direction while maintaining its performance.
Now you can start testing the trinistor. To do this, take KU202N with a working current of 10 A and a voltage of 400 V.
Most radio amateurs have a multimeter and the question inevitably arises, how to check the thyristor with a multimeter, is it possible and what additionally may be needed. The sequence of actions is as follows:
Since the thyristor is controlled by both negative and positive signals, it can be opened by connecting the control electrode to the cathode with a jumper. The multimeter must be in ohmmeter mode and the probes connected to the anode and cathode. So you can determine what voltage the thyristor is controlled by.
The second test option is as follows. A lamp is connected to the DC power supply through the trinistor for the same voltage.
A multimeter is connected to the anode and cathode in the DC voltage measurement mode. The measurement range must exceed the source voltage.
Then, a control voltage is applied to the control electrode using a battery of any rating and a pair of wires. The trinistor should open, the light will light up. The tester first shows the voltage of the power supply, after exposure to a small value, which corresponds to the potential drop across the thyristor in the open state. After that, you can remove the control action, the lamp will continue to burn, since the current flowing through the device is greater than the holding current.
To determine the performance of the dinistor, a power source with a voltage exceeding the turn-on voltage of the dinistor may be required.
To limit the current, you will need a 100-1000 ohm resistor. Now you can connect the plus of the source to the anode, and the cathode to one of the terminals of the limiting resistor. The other end of the resistance is connected to the minus of the power supply.. Before that, you need to connect the multimeter in the DC voltage measurement mode to the anode and cathode. The tester values must be within millivolts. Dinistor opened.
There is another option for checking the thyristor with a multimeter, without ringing. But in this case, the device must be low-power, with a low holding current.
For testing, a transistor test connector is used. It is usually located below the switch and is a round connector about 1 cm in diameter. It should have the following designations: B - means the base of the transistor, C - collector, E - emitter. If the trinistor opens with a positive voltage, then the control output must be connected to the base, the anode with the cathode to the collector and emitter, respectively. Since the tester measures the gain when checking the transistor, in this case it will give some values that will be incorrect. But this is not important, the main thing is to make sure that the trinistor is working.
Sometimes it is required to check the thyristor, without soldering it from the circuit. To do this, turn off the control electrode. After that, a multimeter is connected to the anode and cathode in the DC voltage measurement mode. The second tester is connected to the anode and control electrode of the thyristor. The second instrument must be in ohmmeter mode. If the measuring probes are connected correctly, then the readings of the first tester will lie within a few tens of millivolts. If not, then the probes need to be swapped and everything repeated. Before measurements, you need to make sure that the board and the entire device is de-energized.
In the case of checking a high-voltage thyristor, it will be required. And the check will be carried out with the equipment turned on, since it is difficult to create conditions that simulate the operating parameters of the system. All external influences must be done in accordance with the operating instructions for the equipment. Measurements are made in compliance with safety regulations, otherwise everything is the same as with conventional thyristors.
Thyristors as a separate type of semiconductor, belongs to the category of diodes. But unlike them, the thyristor has a third output, designed to perform the tasks of the control electrode.
In fact, it is a three-terminal diode. Such semiconductor devices are widely used both in household appliances and in power regulators of various light sources.
Given the scale of use of the thyristor, many home craftsmen are faced with the problem of device failure, but they don’t know how and with what to test it. So, for starters, you need to understand what it is and what its principle of operation is.
The thyristor is one of the varieties of semiconductor devices that use p-n junctions as the basis of their work. This is an electronic key with which you can regulate a powerful load using weak signals.
On the electrical goods market, semiconductor devices are presented in a fairly wide range, the classification of which is carried out taking into account the control method and conductivity:
Semiconductor devices of this category are actively used as part of electronic switches, rectifiers, converters, electronic ignition, power regulators.
Thyristors are divided into:
The operation of the switching radio element is reduced to the function of a key. A command is sent to the control electrode, thanks to which the device receives the appropriate position: open or closed.
In addition, devices in this category are classified into lockable and non-lockable.
The operation of the lockable radioelements has been described above. Non-lockable semiconductor products are transferred to the closed mode not due to a command on the control electrode, but on the condition that the current passing through the "anode" and "cathode" takes on a value less than the holding current.
You can test the performance of a semiconductor in the following ways:
Given the frequent failure of the radio element, in order to find the cause of the malfunction in a timely manner, it is desirable to have a convenient combined measuring device of either a simplified modification or a digital version.
To get a reliable result during the test, it is recommended to assemble a special device according to the proposed scheme.
The thyristor structure includes four alternating p and n layers of the p1n1p2n2 conductivity type. Electron-hole transitions are formed between the layers. Layers p1 and n2 and junctions p1n1 and p2n2 are called emitter layers, the inner layers n1 and p2 and the junction between them are basic, and the junction between them is collector.
Connection to the thyristor circuit is possible due to three conclusions:
For verification work on devices of low and medium power, it is necessary to apply voltage to the “anode” and “cathode” terminals, and send a short-term signal to the control electrode to open the conductivity between the “anode” and “cathode”.
In a multimeter, when you set the position of measuring the resistance between the probes, a voltage appears. You can use it when testing the device.
To check a semiconductor device without soldering from almost any circuit, the above method using a multimeter may well be suitable, it is only necessary to disconnect the control electrode from the circuit circuits.
