How to check a thyristor if you are a complete kettle? So, first things first.

The principle of operation of the thyristor

The principle of operation of the thyristor is based on the principle of operation of an electromagnetic relay. The relay is an electromechanical product, and the 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 it 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.

Thyristors look something like this:

And here is the circuit designation of the thyristor

Currently, powerful thyristors are used to switch (switch) 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)

Thyristors, which are on the left, are installed on aluminum radiators, and tablet thyristors even on water-cooled radiators, because a crazy current passes through them and they switch very high power.

Low-power thyristors are used in the radio industry and, of course, in amateur radio.

Thyristor parameters

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 thyristor 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 thyristor and the electric current begins to flow calmly through the two remaining outputs - the anode and cathode of the thyristor. This is the minimum opening voltage of the thyristor.

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 thyristor in the forward direction without harm to his health.

The remaining parameters are not so critical for beginner radio amateurs. You can find them in any reference book.

How to check thyristor KU202N

And finally, we turn to the most important thing - checking the thyristor. We will check the most popular and famous Soviet thyristor - KU202N.

And here is his plinth

To test the thyristor, 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 thyristor.

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 thyristor 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.

How to test a thyristor with a multimeter

You can also check the thyristor with. To do this, we collect it according to this scheme:

Since there is voltage on the probes of the multimeter 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 a 112 millivolt voltage drop. This means that it has opened.

After releasing, the multimeter again shows an infinite 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 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:

The New Year is coming - and Christmas tree decorations and garlands come out of the boxes. And if the toy is simply hung on the place chosen for it, then there are various accidents with garlands. This is especially true for cheap options. Everyone who has ever repaired this miracle of technology knows that the Chinese garland, the scheme of which is simple, has some features.

Features of a garland from China

Most often, the New Year decoration of Chinese masters attracts with a pleasant price (from 150 rubles apiece) and bright lights that flash in several modes. Four types of light bulbs, and sometimes LEDs, are pleasing to the eye and wallet. True, after a while one or several colors stop burning at once. There may be several reasons, but the fact remains - the garland no longer works at 100%.

If the product has deteriorated, it is not necessary to change it for a new one. Although it is customary to enter the New Year in everything new, our hands are not created for boredom. Is it hard to change a burned out light bulb? The point here is not the price and not the time spent on repairs. It's a matter of principle. And every person who first decides to repair a Chinese garland begins to be surprised.

misunderstandings

The most unpleasant surprise during the repair is thin strands of wires. You begin to wonder how it all works and still has not crumbled. It becomes clear both the price of the product and the reliability of operation. This is the Chinese garland. Scheme, repair and search for gaps - this is your further fate. The wiring connection, of course, is the weakest point. Therefore, the search for a gap should begin with a switching box.

In addition to surprisingly thin wiring, the Chinese product can please with a quick failure of the thyristors that control the color lines, as well as the main controller. To replace faulty elements, most often you have to look for domestic analogues or redo the entire circuit.

Types of faults

Let's look at some of possible cases when the scheme of the Chinese garland is not needed. From the course of electrical engineering, only 2 problems associated with electrical malfunctions are known: a short circuit and an open circuit. In the case of a non-working garland, you need to look for a gap. Let's say the blue color is off. 2 options are possible:

• somewhere the wire connecting the blue bulbs broke;
• one of the blue elements burned out.

Now you should find a gap or a burned out light bulb. As a rule, this will help us visual inspection. Most often, the gap is visible to the naked eye, and the repair quickly ends there. To connect the two ends of the wire, you do not even need to have a soldering iron on hand - the simplest twist helps. must be wrapped with electrical tape.

Attention! Any repair of an electrical product is carried out without connecting to the network.

If the gap is not visible, you should pay attention to the box with the button. Chinese garland, the scheme of which does not differ from the standard one, has a control unit in a flat box. By unscrewing 2 or more screws, you can see a small printed circuit board with multiple elements. 2 wires from the plug are suitable for it: phase and zero, as well as 4 wires with bulbs of four different colors. Breaks most often occur at the junction of the conductors of the wiring.

A number of malfunctions are associated with a malfunction. Here, the mode switch button itself may fail. Such a problem is "treated" by cleaning the contacts or a complete replacement. The Chinese garland, the scheme of which is standard, necessarily includes a controller. It can also deteriorate and can be replaced too. The weak link can be any of the 4 thyristors - one for each color.

Item replacement problem

To replace faulty elements, Chinese colleagues offer their own. The problem is that the lamps become obsolete quickly enough, and it can be problematic to find the right version of Chinese production. In this case, the domestic element base comes to the rescue. The most important thing is to choose the right analogue.

To select an analogue of the desired element, it is important to know the parameters of the Chinese product. Often on the forums they look for the PCR406J transistor. The Chinese garland, the scheme of which is made on such elements, is familiar. Only the desired element actually turns out to be a thyristor, and its Russian counterpart MCR100 is almost identical in parameters.

Looking to break the chain

What to do if no breaks are found? The scheme of the Chinese garland is simple. All bulbs are connected in series. So, if the blue line is off, you need to find at least one burned out line. There are two options.

• Check successively all the elements in the chain.
• Search for a faulty light bulb by dividing the line in half. Having found a half that does not pass current, you need to divide it in half again. And so on until a problem is found. After replacing the lamp, all pieces must be reassembled. It is better to do this with a soldering iron, but you can get by with twisting or electrical tape.

The second method can be omitted if you use a multimeter with thin needles attached to the ends of the probes. However, the veins of the conductors used in Chinese products are so thin that they can be torn even with a needle.

It happens that there is no second damaged garland and a new light bulb at hand. In this case, you can simply connect the two ends together. This is fraught with an increase in voltage on the remaining bulbs, since, according to the laws of electrical engineering, in a series circuit, the voltage is divided equally. But if you remove one or two elements, this will not greatly affect the service life. Despite the fact that the Chinese, everything works on general principles.

LED garlands

Such products have become widespread in recent years. In this regard, low-power elements appeared on the garlands instead of light bulbs. The Chinese scheme differs little from the standard one. But, given the fact that the LED is designed for a much lower voltage, each of them will have a resistor in the circuit for a 220 V network. In another option, a step-down transformer will be implemented at the input of the system.

In addition to the usual scheme, where the elements are arranged in series, there is a scheme of a Chinese garland on LEDs placed in parallel. With this option, even the burnout of several light elements at once will not introduce dissonance into the overall picture.

Advantages of LED Products

The Chinese garland, the circuit of which is built on LEDs, has a number of advantages.

• Profitability. This is due to the low power consumption of LEDs. The following two advantages immediately follow from this.
• Durability. The service life of LED products is two or more times longer than the service life of incandescent lamps.
• Safety. LEDs, unlike incandescent lamps, can heat up to a maximum of 60 degrees. Therefore, they are less flammable than their counterparts.
• Brightness. Garlands on LEDs are brighter and more pleasing to the eye.
• Frost resistance. LED products can withstand temperatures down to 40 degrees below zero without a change in performance.
• Moisture resistance. Such garlands can be used to decorate bathrooms and wet greenhouses.

LED Chinese garlands are very convenient to use to decorate the outdoor part of the house. Due to the high moisture and frost resistance, such products will please the eye for a long time without repair.

Conclusion

Buying such a product, it is not always possible to please yourself and loved ones with a quality decoration. Sometimes a rather simple and cheap Chinese garland is hidden behind bright lights and attractive prices. Its scheme will be easy to learn and convenient for the application of electrical skills. Repair of the product can also bring moral satisfaction. Everyone decides for himself whether it is worth the time and effort. Or maybe it's better to immediately take the more expensive option? After all, even Chinese garlands for a high price are much better than their cheap "compatriots". The choice is yours!

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