Thyristor power regulators are one of the most common amateur radio designs, and this is not surprising. After all, everyone who has ever used a regular 25 - 40 watt soldering iron is well aware of its ability to overheat. The soldering iron begins to smoke and hiss, then, soon enough, the tinned tip burns out and turns black. Soldering with such a soldering iron is no longer possible.

And this is where the power regulator comes to the rescue, with which you can quite accurately set the temperature for soldering. You should be guided by the fact that when you touch a piece of rosin with a soldering iron, it smokes well, moderately, without hissing or splashing, and not very energetically. You should focus on ensuring that the soldering is contoured and shiny.

In order not to complicate the story, we will not consider the thyristor in the form of its four-layer p-n-p-n structure, draw the current-voltage characteristic, but simply describe in words how it, the thyristor, works. To begin with, in DC circuits, although thyristors are almost never used in these circuits. After all, turning off a thyristor operating on direct current is quite difficult. It's like stopping a galloping horse.

And yet, high currents and high voltages of thyristors attract developers of various, usually quite powerful, direct current equipment. To turn off thyristors, one has to resort to various circuit complications and tricks, but in general the results are positive.

The designation of a thyristor on circuit diagrams is shown in Figure 1.

Figure 1. Thyristor

It is easy to see that, by its designation on the diagrams, the thyristor is very similar to. If you look at it, it, the thyristor, also has one-way conductivity, and therefore can rectify alternating current. But it will only do this if a positive voltage is applied to the control electrode relative to the cathode, as shown in Figure 2. According to the old terminology, a thyristor was sometimes called a controlled diode. As long as a control pulse is not applied, the thyristor is closed in any direction.

Figure 2.

How to turn on the LED

Everything is very simple here. An HL1 LED with a limiting resistor R3 is connected to a 9V constant voltage source (you can use a Krona battery) through a thyristor Vsx. Using the SB1 button, the voltage from the divider R1, R2 can be applied to the control electrode of the thyristor, and then the thyristor will open and the LED will light up.

If you now release the button and stop holding it down, the LED should continue to light. Such a short press on the button can be called pulsed. Repeated or even repeated pressing of this button will not change anything: the LED will not go out, but will not shine brighter or dimmer.

They pressed and released, and the thyristor remained open. Moreover, this state is stable: the thyristor will be open until external influences remove it from this state. This behavior of the circuit indicates the good condition of the thyristor, its suitability for operation in the device being developed or repaired.

Small note

But there are often exceptions to this rule: the button was pressed, the LED lit up, and when the button was released, it went out, as if nothing had happened. And what’s the catch here, what did they do wrong? Maybe the button was not pressed long enough or not very fanatically? No, everything was done quite conscientiously. It’s just that the current through the LED turned out to be less than the holding current of the thyristor.

For the described experiment to be successful, you just need to replace the LED with an incandescent lamp, then the current will increase, or select a thyristor with a lower holding current. This parameter for thyristors has a significant spread, sometimes it is even necessary to select a thyristor for a specific circuit. And of the same brand, with the same letter and from the same box. Imported thyristors, which have recently been preferred, are somewhat better with this current: it’s easier to buy and the parameters are better.

How to close a thyristor

No signals sent to the control electrode can close the thyristor and turn off the LED: the control electrode can only turn on the thyristor. There are, of course, lockable thyristors, but their purpose is somewhat different than banal power regulators or simple switches. An ordinary thyristor can be turned off only by interrupting the current through the anode - cathode section.

This can be done in at least three ways. Firstly, it’s stupid to disconnect the entire circuit from the battery. Recall Figure 2. Naturally, the LED will go out. But when reconnected, it will not turn on by itself, since the thyristor remains in the closed state. This condition is also stable. And to get him out of this state, to turn on the light, only pressing the SB1 button will help.

The second way to interrupt the current through the thyristor is to simply short-circuit the cathode and anode terminals with a jumper wire. In this case, the entire load current, in our case it is just an LED, will flow through the jumper, and the current through the thyristor will be zero. After the jumper is removed, the thyristor will close and the LED will turn off. When experiments with such circuits, tweezers are most often used as a jumper.

Let's assume that instead of an LED in this circuit there will be a fairly powerful heating coil with high thermal inertia. Then you get an almost ready-made power regulator. If you switch the thyristor in such a way that the spiral is on for 5 seconds and off for the same amount of time, then 50 percent of the power is released in the spiral. If during this ten-second cycle the switch is turned on for only 1 second, then it is quite obvious that the coil will release only 10% of the heat of its power.

The power control in a microwave oven operates in approximately these time cycles, measured in seconds. Simply using a relay, the HF radiation is turned on and off. Thyristor regulators operate at the frequency of the supply network, where time is measured in milliseconds.

The third way to turn off the thyristor

It consists of reducing the load supply voltage to zero, or even completely changing the polarity of the supply voltage to the opposite. This is exactly the situation that occurs when thyristor circuits are powered with alternating sinusoidal current.

When the sinusoid passes through zero, it changes sign to the opposite one, so the current through the thyristor becomes less than the holding current, and then completely equal to zero. Thus, the problem of turning off the thyristor is solved as if by itself.

Thyristor power regulators. Phase regulation

So, the matter remains small. To achieve phase control, you simply need to apply a control pulse at a certain time. In other words, the pulse must have a certain phase: the closer it is to the end of the half-cycle of the alternating voltage, the smaller the voltage amplitude will be across the load. The phase control method is shown in Figure 3.

Figure 3. Phase control

In the upper fragment of the picture, the control pulse is supplied almost at the very beginning of the half-cycle of the sinusoid, the phase of the control signal is close to zero. In the figure, this is time t1, so the thyristor opens almost at the beginning of the half-cycle, and the load releases power close to the maximum (if there were no thyristors in the circuit, the power would be maximum).

The control signals themselves are not shown in this figure. Ideally, they are short pulses positive relative to the cathode, applied in a certain phase to the control electrode. In the simplest circuits, this can be a linearly increasing voltage obtained when charging a capacitor. This will be discussed below.

In the middle graph, the control pulse is applied in the middle of the half-cycle, which corresponds to the phase angle Π/2 or time t2, so only half of the maximum power is released into the load.

In the lower graph, the opening pulses are supplied very close to the end of the half-cycle, the thyristor opens almost before it is about to close, according to the graph this time is designated as t3, accordingly, insignificant power is released in the load.

Thyristor switching circuits

After a brief consideration of the operating principle of thyristors, we can probably give several power regulator circuits. Nothing new has been invented here; everything can be found on the Internet or in old radio engineering magazines. The article simply provides a brief overview and description of the work thyristor regulator circuits. When describing the operation of the circuits, attention will be paid to how thyristors are used, what circuits exist for connecting thyristors.

As was said at the very beginning of the article, a thyristor rectifies alternating voltage like a regular diode. This results in half-wave rectification. Once upon a time, incandescent lamps in staircases were turned on this way, through a diode: there was very little light, it dazzled the eyes, but the lamps burned out very rarely. The same thing will happen if the dimmer is made on one thyristor, only it becomes possible to regulate the already insignificant brightness.

Therefore, power regulators control both half-cycles of the mains voltage. For this purpose, counter-parallel connection of thyristors is used, or connection of a thyristor to the diagonal of the rectifier bridge.

To make this statement clearer, several circuits of thyristor power regulators will be considered below. Sometimes they are called voltage regulators, and it is difficult to decide which name is more correct, because along with voltage regulation, power is also regulated.

The simplest thyristor regulator

It is designed to regulate the power of the soldering iron. Its diagram is shown in Figure 4.

Figure 4. Diagram of a simple thyristor power regulator

There is no point in adjusting the power of the soldering iron starting from zero. Therefore, we can limit ourselves to regulating only one half-cycle of the mains voltage, in this case positive. The negative half-cycle passes without changes through the diode VD1 directly to the soldering iron, which provides its half power.

The positive half-cycle passes through the thyristor VS1, which allows regulation. The thyristor control circuit is extremely simple. These are resistors R1, R2 and capacitor C1. The capacitor is charged through the circuit: the top wire of the circuit, R1, R2 and capacitor C1, the load, the bottom wire of the circuit.

The control electrode of the thyristor is connected to the positive terminal of the capacitor. When the voltage on the capacitor increases to the turn-on voltage of the thyristor, the latter opens, passing a positive half-cycle of voltage, or rather part of it, into the load. At the same time, capacitor C1 naturally discharges, thereby preparing for the next cycle.

The charging rate of the capacitor is controlled using variable resistor R1. The faster the capacitor is charged to the opening voltage of the thyristor, the sooner the thyristor opens, the larger part of the positive half-cycle of the voltage goes to the load.

The circuit is simple, reliable, and quite suitable for a soldering iron, although it regulates only one half-cycle of the mains voltage. A very similar circuit is shown in Figure 5.

Figure 5. Thyristor power regulator

It is somewhat more complex than the previous one, but allows adjustment more smoothly and accurately, due to the fact that the circuit for generating control pulses is assembled on a dual-base transistor KT117. This transistor is designed to create pulse generators. He seems incapable of anything else. A similar circuit is used in many power regulators, as well as in switching power supplies as a trigger pulse shaper.

As soon as the voltage on capacitor C1 reaches the operating threshold of the transistor, the latter opens and a positive pulse appears at terminal B1, opening the thyristor VS1. Resistor R1 can be used to regulate the charging rate of the capacitor.

The faster the capacitor charges, the sooner the opening pulse appears, the greater the voltage supplied to the load. The second half-wave of the mains voltage passes to the load through the VD3 diode without changes. To power the control pulse shaper circuit, rectifier VD2, R5, and zener diode VD1 are used.

Here you can ask, when will the transistor open, what is the operating threshold? The opening of the transistor occurs at the moment when the voltage at its emitter E exceeds the voltage at the base B1. Bases B1 and B2 are not equivalent; if they are swapped, the generator will not work.

Figure 6 shows a circuit that allows you to regulate both half-cycles of the voltage.

Figure 6.

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I use this design for a homemade electric stove on which we cook porridge for dogs, and recently I applied it to a soldering iron.

To make this regulator we will need:

A pair of 1 kOhm resistors can even be 0.25w, one 1 mOhm variable resistor, two 0.01 µF capacitors and
47 nF, one dinistor that I took from an economy light bulb, the dinistor has no polarity so you can solder it however you like, we also need a triac with a small radiator, I used a triac of the TC series in a metal case for 10 amperes, but you can use KU208G, We also need screw terminal blocks.

Yes, by the way, a little about the variable resistor, if you set it to 500 kOhm, it will regulate quite smoothly, but only from 220 to 120 volts, and if it is set to 1 mOhm, then it will be strictly regulated with an interval of 5-10 volts, but the range will increase from 220 to 60 volt.
So let's start assembling our power regulator, for this we first need to make a printed circuit board.

After the printed circuit board is ready, we begin assembling radio components on the printed circuit board. First of all, we solder the screw terminal blocks.

And last but not least, we install the radiator and triac.

That's it, our voltage regulator is ready, let's wash the board with alcohol and check it.

A more detailed overview of the triac regulator in the video clip. Happy assembly.

Powerful 220V mains voltage regulator

Recently, in our everyday life, electronic devices are increasingly being used to smoothly regulate the mains voltage. With the help of such devices, they control the brightness of lamps, the temperature of electric heating devices, and the rotation speed of electric motors.

The vast majority of voltage regulators based on thyristors have significant disadvantages that limit their capabilities. Firstly, they introduce quite noticeable interference into the electrical network, which often negatively affects the operation of televisions, radios, and tape recorders. Secondly, they can only be used to control a load with active resistance - an electric lamp or a heating element, and cannot be used in conjunction with an inductive load - an electric motor, a transformer.

Meanwhile, all these problems can be easily solved by assembling an electronic device in which the role of a regulating element would be played not by a thyristor, but by a powerful transistor.

Schematic diagram

The transistor voltage regulator (Fig. 9.6) contains a minimum of radio elements, does not interfere with the electrical network and operates on a load with both active and inductive resistance. It can be used to adjust the brightness of a chandelier or table lamp, the heating temperature of a soldering iron or hotplate, the rotation speed of a fan or drill motor, and the voltage on the transformer winding. The device has the following parameters: voltage adjustment range - from 0 to 218 V; the maximum load power when using one transistor in the control circuit is no more than 100 W.

The regulating element of the device is transistor VT1. Diode bridge VD1. VD4 rectifies the mains voltage so that a positive voltage is always applied to the collector VT1. Transformer T1 reduces the voltage of 220 V to 5.8 V, which is rectified by the diode unit VD6 and smoothed by capacitor C1.

Rice. Schematic diagram of a powerful 220V mains voltage regulator.

Variable resistor R1 serves to adjust the control voltage, and resistor R2 limits the base current of the transistor. Diode VD5 protects VT1 from negative polarity voltage reaching its base. The device is connected to the network using an XP1 plug. The XS1 socket is used to connect the load.

The regulator operates as follows. After turning on the power with toggle switch S1, the mains voltage is supplied simultaneously to diodes VD1, VD2 and the primary winding of transformer T1.

In this case, a rectifier consisting of a diode bridge VD6, a capacitor C1 and a variable resistor R1 generates a control voltage that goes to the base of the transistor and opens it. If at the moment the regulator is turned on, there is a voltage of negative polarity in the network, the load current flows through the circuit VD2 - emitter-collector VT1, VD3. If the polarity of the mains voltage is positive, current flows through the circuit VD1 - collector-emitter VT1, VD4.

The value of the load current depends on the value of the control voltage based on VT1. By rotating the R1 slider and changing the value of the control voltage, the magnitude of the collector current VT1 is controlled. This current, and therefore the current flowing in the load, will be greater the higher the control voltage level, and vice versa.

When the variable resistor motor is in the extreme right position according to the diagram, the transistor will be completely open and “dose9raquo; the electricity consumed by the load will correspond to the nominal value. If the R1 slider is moved to the extreme left position, VT1 will be locked and no current will flow through the load.

By controlling the transistor, we actually regulate the amplitude of the alternating voltage and current acting in the load. At the same time, the transistor operates in continuous mode, due to which such a regulator is free of the disadvantages inherent in thyristor devices.

Construction and details

Now let's move on to the design of the device. Diode bridges, a capacitor, resistor R2 and diode VD6 are installed on a circuit board measuring 55x35 mm, made of foil getinax or textolite 1.2 mm thick (Fig. 9.7).

The following parts can be used in the device. Transistor - KT812A(B), KT824A(B), KT828A(B), KT834A(B,V), KT840A(B), KT847A or KT856A. Diode bridges: VD1. VD4 - KTs410V or KTs412V, VD6 - KTs405 or KTs407 with any letter index; diode VD5 - series D7, D226 or D237.

Variable resistor - type SP, SPO, PPB with a power of at least 2 W, constant - BC, MJIT, OMLT, S2-23. Oxide capacitor - K50-6, K50-16. Network transformer - TVZ-1-6 from tube TVs, TS-25, TS-27 - from the Yunost9raquo TV; or any other low-power with a secondary winding voltage of 5.8 V.

The fuse is designed for a maximum current of 1 A. The toggle switch is TZ-S or any other network switch. XP1 is a standard power plug, XS1 is a socket.

All elements of the regulator are housed in a plastic case with dimensions of 150x100x80 mm. A toggle switch and a variable resistor equipped with a decorative handle are installed on the top panel of the case. The socket for connecting the load and the fuse socket are mounted on one of the side walls of the housing.

On the same side there is a hole for the power cord. A transistor, transformer and circuit board are installed at the bottom of the case. The transistor must be equipped with a radiator with a dissipation area of ​​at least 200 cm2 and a thickness of 3.5 mm.

Rice. Printed circuit board of a powerful 220V mains voltage regulator.

The regulator does not need to be adjusted. With proper installation and serviceable parts, it begins to work immediately after being plugged into the network.

Now some recommendations for those who want to improve the device. The changes mainly concern increasing the output power of the regulator. So, for example, when using the KT856 transistor, the power consumed by the load from the network can be 150 W, for KT834 - 200 W, and for KT847 - 250 W.

If it is necessary to further increase the output power of the device, several parallel-connected transistors can be used as a control element by connecting their corresponding terminals.

Probably, in this case, the regulator will have to be equipped with a small fan for more intensive air cooling of semiconductor devices. In addition, the diode bridge VD1. VD4 will need to be replaced with four more powerful diodes, designed for an operating voltage of at least 600 V and a current value in accordance with the consumed load.

Devices of the D231 series are suitable for this purpose. D234, D242, D243, D245. D248. It will also be necessary to replace VD5 with a more powerful diode, rated for current up to I A. Also, the fuse must withstand a higher current.

DIY power regulator

The modern power supply network is designed in such a way that power surges often occur in it. Current changes are permissible, but they should not exceed 10% of the accepted 220 volts. Jumps have a bad effect on the performance of various electrical appliances, and very often they begin to malfunction. To prevent this from happening, we began to use stable power regulators to equalize the incoming current. If you have a certain imagination and skills, you can make various types of stabilization devices, and the most effective is the triac stabilizer.

On the market, such devices are either expensive or often of poor quality. It is clear that few people would want to overpay and get an ineffective device. In this case, you can assemble it from scratch with your own hands. This is how the idea of ​​creating a power regulator based on a dimmer arose. Thank God I had a dimmer, but it was a little ineffective.

Repairing a triac regulator - Dimmer

This image shows the factory electrical circuit of a dimmer from Leviton, which operates from a 120-volt network. If an inspection of non-working dimmers shows that only the triac has burned out, then you can begin the procedure for replacing it. But surprises may await you here. The fact is that there are dimmers in which some strange triacs with different numbers are installed. It is quite possible that you will not be able to find information on them even on the datasheet. In addition, for such triacs, the contact pad is isolated from the electrodes of the triac (triac). Although, as you can see, the contact pad is made of copper and is not even covered with plastic, like the transistor housings. Such triacs are very convenient to repair.

Also pay attention to the method of soldering triacs to the radiator, it is made using rivets, they are hollow. When using insulating gaskets, it is not recommended to use this method of fastening. Yes, such a fastening is not very reliable. In general, repairing such a triac will take a lot of time and you will waste your nerves precisely because of the installation of this type of triac; the dimmer is simply not designed for such a triac size.

Hollow rivets should be removed using a drill that is sharpened at a certain angle. and more specifically at an angle of 90°, you can also use side cutters for this work.

If you do not work carefully, there is a possibility of damage to the radiator. to avoid this, it is more correct to do it only on that side. Where is the triac located?

Radiators made of very soft aluminum may be slightly deformed when riveted. Therefore, it is necessary to sand the contact surfaces using sandpaper.

If you are using a triac that does not have galvanic isolation between the electrodes and the pad, you must use an effective isolation method.

The image shows. how it's done. So as not to accidentally push through the walls of the radiator in that place. where the triac is attached, it is necessary to grind off most of the cap of the screw in order to avoid it getting caught on the handrail of the potentiometer or power stabilizer, and then a washer must be placed under the head of the screw.

This is what a triac should look like after being isolated from the radiator. For the best heat removal, you need to purchase a special thermal conductive paste KPT-8.

The picture shows what is under the radiator shroud

Everything should work now

Factory power regulator diagram

Based on the diagram of a factory power regulator, you can assemble a regulator layout for your network voltage.

Here is a diagram of the regulator, which is adapted for operation in a network with a static voltage of 220 Volts. This circuit differs from the original only in a few details, namely, during the repair, the power of the resistor R1 was increased several times, the ratings of R4 and R5 were reduced by 2, and the dinistor was 60. in the volt one they replaced it with two. which are connected in series with 30-volt dinistors VD1, VD2. As you can see, you can not only repair faulty dimmers with your own hands, but also easily adjust them to your needs.

This is a working layout of the power regulator. Now you know exactly what kind of scheme you will get with proper repairs. This scheme does not require the selection of additional parts and is immediately ready for use. It may be necessary to adjust the position of the slider of the substring resistor R4. For these purposes, the sliders of the potentiometers R4 and R5 are set to the highest position, and then the position of the slider R4 is changed, after which the lamp will light up with the lowest brightness, and then the slider should be slightly moved in the opposite direction. This completes the setup process! But it is worth noting that this power regulator only works with heating devices and incandescent lamps, and with engines or powerful devices the results may not be unpredictable. For beginner amateur craftsmen with little experience, such work is just right.

AC VOLTAGE REGULATOR

Hi all! In the last article I told you how to make a voltage regulator for DC. Today we will make a voltage regulator for 220V AC. The design is quite simple to repeat even for beginners. But at the same time, the regulator can take on a load of even 1 kilowatt! To make this regulator we need several components:

1. Resistor 4.7 kOhm mlt-0.5 (even 0.25 watt will do).
2. A variable resistor 500kOhm-1mOhm, with 500kOhm it will regulate quite smoothly, but only in the range of 220V-120V. With 1 mOhm - it will regulate more tightly, that is, it will regulate with a gap of 5-10 volts, but the range will increase, it is possible to regulate from 220 to 60 volts! It is advisable to install the resistor with a built-in switch (although you can do without it by simply installing a jumper).
3. Dinistor DB3. You can get one from economical LSD lamps. (Can be replaced with domestic KH102).
4. Diode FR104 or 1N4007, such diodes are found in almost any imported radio equipment.
5. Current-efficient LEDs.
6. Triac BT136-600B or BT138-600.
7. Screw terminal blocks. (you can do without them by simply soldering the wires to the board).
8. Small radiator (up to 0.5 kW it is not needed).
9. Film capacitor 400 volt, from 0.1 microfarad to 0.47 microfarad.

AC voltage regulator circuit:

Let's start assembling the device. First, let's etch and tin the board. The printed circuit board - its drawing in LAY, is in the archive. A more compact version presented by a friend sergei- here.

Then we solder the capacitor. The photo shows the capacitor from the tinning side, because my example of the capacitor had too short legs.

We solder the dinistor. The dinistor has no polarity, so we insert it as you wish. We solder the diode, resistor, LED, jumper and screw terminal block. It looks something like this:

And in the end, the last stage is to install a radiator on the triac.

And here is a photo of the finished device already in the case.

The regulator does not require any additional settings. Video of this device working:

I would like to note that you can install it not only in a 220V network on ordinary appliances and power tools. but also to any other alternating current source with a voltage from 20 to 500V (limited by the maximum parameters of the circuit’s radio elements). I was with you Boil-:D

Operating principle of triac power regulators

A semiconductor device that has 5 p-n junctions and is capable of passing current in the forward and reverse directions is called a triac. Due to the inability to operate at high frequencies of alternating current, high sensitivity to electromagnetic interference and significant heat generation when switching large loads, they are currently not widely used in high-power industrial installations.

There they are successfully replaced by circuits based on thyristors and IGBT transistors. But the compact dimensions of the device and its durability, combined with the low cost and simplicity of the control circuit, allowed them to be used in areas where the above disadvantages are not significant.

Today, triac circuits can be found in many household appliances from hair dryers to vacuum cleaners, hand-held power tools and electric heating devices - where smooth power adjustment is required.

Principle of operation

The power regulator on a triac works like an electronic key, periodically opening and closing at a frequency specified by the control circuit. When unlocked, the triac passes part of the half-wave of the mains voltage, which means the consumer receives only part of the rated power.

Do it yourself

Today, the range of triac regulators on sale is not very large. And, although the prices for such devices are low, they often do not meet consumer requirements. For this reason, we will consider several basic circuits of regulators, their purpose and the element base used.

Device diagram

The simplest version of the circuit, designed to work with any load. Traditional electronic components are used, the control principle is phase-pulse.

• triac VD4, 10 A, 400 V;
• dinistor VD3, opening threshold 32 V;
• potentiometer R2.

The current flowing through potentiometer R2 and resistance R3 charges capacitor C1 with each half-wave. When the voltage on the capacitor plates reaches 32 V, the dinistor VD3 opens and C1 begins to discharge through R4 and VD3 to the control terminal of the triac VD4, which opens to allow current to flow to the load.

The opening duration is regulated by selecting the threshold voltage VD3 (constant value) and resistance R2. The power in the load is directly proportional to the resistance value of potentiometer R2.

An additional circuit of diodes VD1 and VD2 and resistance R1 is optional and serves to ensure smooth and accurate adjustment of the output power. The current flowing through VD3 is limited by resistor R4. This achieves the pulse duration required to open VD4. Fuse Pr.1 protects the circuit from short circuit currents.

A distinctive feature of the circuit is that the dinistor opens at the same angle in each half-wave of the mains voltage. As a result, the current does not rectify, and it becomes possible to connect an inductive load, for example a transformer.

Triacs should be selected according to the load size, based on the calculation of 1 A = 200 W.

• Dinistor DB3;
• Triac TS106-10-4, VT136-600 or others, the required current rating is 4-12A.
• Diodes VD1, VD2 type 1N4007;
• Resistances R1100 kOhm, R3 1 kOhm, R4 270 Ohm, R5 1.6 kOhm, potentiometer R2 100 kOhm;
• Capacitor C1 0.47 µF (operating voltage from 250 V).

Note that the scheme is the most common, with minor variations. For example, a dinistor can be replaced with a diode bridge, or an interference-suppressing RC circuit can be installed in parallel with the triac.

A more modern circuit is one that controls the triac from a microcontroller - PIC, AVR or others. This circuit provides more accurate regulation of voltage and current in the load circuit, but is also more complex to implement.

Triac power regulator circuit

The power regulator must be assembled in the following sequence:

1. Determine the parameters of the device on which the device being developed will work. Parameters include: number of phases (1 or 3), the need for precise adjustment of output power, input voltage in volts and rated current in amperes.
2. Select the type of device (analog or digital), select elements according to load power. You can check your solution in one of the programs for modeling electrical circuits - Electronics Workbench, CircuitMaker or their online analogues EasyEDA, CircuitSims or any other of your choice.
3. Calculate the heat dissipation using the following formula: voltage drop across the triac (about 2 V) multiplied by the rated current in amperes. The exact values ​​of the voltage drop in the open state and the rated current flow are indicated in the characteristics of the triac. We get the power dissipation in watts. Select a radiator according to the calculated power.
4. Purchase the necessary electronic components. heatsink and printed circuit board.
5. Lay out contact tracks on the board and prepare sites for installing elements. Provide mounting on the board for a triac and radiator.
6. Install the elements on the board using soldering. If it is not possible to prepare a printed circuit board, then you can use surface mounting to connect the components using short wires. When assembling, pay special attention to the polarity of connecting the diodes and triac. If there are no pin markings on them, then test them using a digital multimeter or a “dragstick”.
7. Check the assembled circuit with a multimeter in resistance mode. The resulting product must correspond to the original design.
8. Securely attach the triac to the radiator. Don’t forget to lay an insulating heat transfer gasket between the triac and the radiator. The fastening screw is securely insulated.
9. Place the assembled circuit in a plastic case.
10. Remember that at the terminals of the elements Dangerous voltage is present.
11. Turn the potentiometer to minimum and perform a test run. Measure the voltage at the regulator output with a multimeter. Smoothly turn the potentiometer knob to monitor the change in output voltage.
12. If the result is satisfactory, then you can connect the load to the output of the regulator. Otherwise, it is necessary to make power adjustments.

Triac power radiator

Power adjustment

The power control is controlled by a potentiometer, through which the capacitor and the capacitor discharge circuit are charged. If the output power parameters are unsatisfactory, you should select the resistance value in the discharge circuit and, if the power adjustment range is small, the potentiometer value.

• extend lamp life, adjust lighting or soldering iron temperature A simple and inexpensive regulator using triacs will help.
• select the circuit type and component parameters according to the planned load.
• work it out carefully circuit solutions.
• be careful when assembling the circuit. Observe the polarity of semiconductor components.
• do not forget that electric current exists in all elements of the circuit and it is deadly to humans.

Checking the capacitor with a multimeter

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A few days ago I bought a small drill for drilling printed circuit boards, but unfortunately, it rotates at a constant frequency, but I would like to regulate the speed of this drill.

I rummaged around on the Internet and found a diagram of a transistor voltage regulator for a “fun power supply” (Author of the Yunost TV channel)

But -12 and +12 (if we take these pins from the computer power supply) will give a total of 24V, but at the output of our regulator we have only 9V. Not in order. I thought and decided to throw another zener diode “D814B” into the circuit, the same as in our 9V circuit, and connect it in series, then the total stabilization voltage will be equal to 18V. And this voltage is quite enough for our mini drill..

And so, let's go, we need:
1 resistor 560 Ohm
2 resistors per 1 kOhm
1 tuning resistor for 10 Kom
1 transistor MP42, MP41 is also possible (I used this one)
1 transistor P213
2 zener diodes "D814B"
Soldering accessories
A piece of PCB (in my case, an ordinary piece of plastic)
Wires
Pliers
Wire cutters

First, let’s change our diagram so that you can understand it and so that you don’t get confused.

Now we have a diagram according to which we will assemble our device..

When we have a diagram and all the parts we need, we can safely start assembling

We take our plastic and make holes in it to install parts

Next, we install the parts on our piece of plastic (textolite)

Important!! Transistor P213 should be installed on the radiator and installed in our circuit in place with the radiator. It’s better to fix the wires with hot glue or epoxy, because during installation I managed to break off the emitter terminal

Next, we insert the wires from P213 into the holes on the other side of our structure

Then we assemble everything according to the diagram, and this is what we get in the end

DIY voltage regulator

In this article we will look at how do it yourself simple voltage regulator on one variable resistor, fixed resistor, and transistor. Which is useful for regulating the voltage on the power supply or universal adapter for powering devices.

And since our scheme is for beginners.

Then we will consider all aspects.

First, let's look at the device diagram. You can see it below, and you can enlarge it by clicking.

We begin to assemble; first, for convenience, the drawing can be printed. We print it 1 to 1. And cut it out without pictures. We apply it to the PCB from the foil side. This will make it easier for us to mark and drill holes.

After drilling the holes. We draw paths on the PCB foil with a permanent marker.

We cut off the remaining testolite and begin soldering the components. First we solder the transistor, just be careful - do not mix up the legs on the transistor (emitter and base).

Next we install a 1k resistor, then solder in a 10k variable resistor with wires. You can put another resistor, immediately solder the resistor without these snot, but my resistor did not allow this, and I had to hang it on the wires... It remains to solder 4 pins to the power supply, and to the outputs.

Thyristor voltage regulators are devices designed to regulate the speed and torque of electric motors. Regulation of rotation speed and torque is carried out by changing the voltage supplied to the motor stator, and is carried out by changing the opening angle of the thyristors. This method of controlling an electric motor is called phase control. This method is a type of parametric (amplitude) control.

They can be performed with both closed and open control systems. Open-loop regulators do not provide satisfactory speed control. Their main purpose is to regulate torque to obtain the desired operating mode of the drive in dynamic processes.

The power part of a single-phase thyristor voltage regulator includes two controlled thyristors, which ensure the flow of electric current at the load in two directions with a sinusoidal voltage at the input.

Thyristor regulators with closed control system are used, as a rule, with negative speed feedback, which makes it possible to have fairly rigid mechanical characteristics of the drive in the low-speed zone.

Most effective use thyristor regulators for speed and torque control.

Power circuits of thyristor regulators

In Fig. 1, a-d shows possible circuits for connecting the rectifier elements of the regulator in one phase. The most common of them is the diagram in Fig. 1, a. It can be used with any stator winding connection scheme. The permissible current through the load (rms value) in this circuit in continuous current mode is equal to:

Where I t - permissible average value of current through the thyristor.

Maximum forward and reverse voltage of the thyristor

Where k zap - safety factor selected taking into account possible switching overvoltages in the circuit; - effective value of the line voltage of the network.

Rice. 1. Diagrams of power circuits of thyristor voltage regulators.

In the diagram in Fig. 1b there is only one thyristor connected to the diagonal of the bridge of uncontrolled diodes. The relationship between the load and thyristor currents for this circuit is:

Uncontrolled diodes are selected for a current half as much as for a thyristor. Maximum forward voltage on the thyristor

The reverse voltage across the thyristor is close to zero.

Scheme in Fig. 1, b has some differences from the diagram in Fig. 1, and on the construction of a control system. In the diagram in Fig. 1, and control pulses to each of the thyristors must follow the frequency of the supply network. In the diagram in Fig. 1b, the frequency of control pulses is twice as high.

Scheme in Fig. 1, c, consisting of two thyristors and two diodes, in terms of control capability, loading, current and maximum forward voltage of the thyristors is similar to the circuit in Fig. 1, a.

The reverse voltage in this circuit is close to zero due to the shunting effect of the diode.

Scheme in Fig. 1, g in terms of current and maximum forward and reverse voltage of the thyristors is similar to the circuit in Fig. 1, a. Scheme in Fig. 1, d differs from those considered in the requirements for the control system to ensure the required range of change in the control angle of the thyristors. If the angle is measured from zero phase voltage, then for the circuits in Fig. 1, a-c the relationship is correct

Where φ - load phase angle.

For the diagram in Fig. 1, d a similar relationship takes the form:

The need to increase the range of angle changes complicates things. Scheme in Fig. 1, d can be used when the stator windings are connected in a star without a neutral wire and in a triangle with the inclusion of rectifier elements in the linear wires. The scope of application of this scheme is limited to non-reversible, as well as reversible electric drives with contact reverse.

Scheme in Fig. 4-1, d is similar in its properties to the diagram in Fig. 1, a. The triac current here is equal to the load current, and the frequency of the control pulses is equal to double the frequency of the supply voltage. The disadvantage of a circuit based on triacs is that the permissible values ​​of du/dt and di/dt are significantly lower than those of conventional thyristors.

For thyristor regulators, the most rational diagram is in Fig. 1, but with two back-to-back thyristors.

The power circuits of the regulators are made with back-to-back thyristors connected in all three phases (symmetrical three-phase circuit), in two and one phase of the motor, as shown in Fig. 1, f, g and h, respectively.

In regulators used in crane electric drives, the most widespread is the symmetrical connection circuit shown in Fig. 1, e, which is characterized by the least losses from higher harmonic currents. Higher loss values ​​in circuits with four and two thyristors are determined by voltage asymmetry in the motor phases.

Basic technical data of thyristor regulators of the PCT series

Thyristor regulators of the PCT series are devices for changing (according to a given law) the voltage supplied to the stator of an asynchronous motor with a wound rotor. Thyristor regulators of the PCT series are made according to a symmetrical three-phase switching circuit (Fig. 1, e). The use of regulators of this series in crane electric drives allows for regulation of rotation speed in the range of 10:1 and regulation of engine torque in dynamic modes during start-up and braking.

Thyristor regulators of the PCT series are designed for continuous currents of 100, 160 and 320 A (maximum currents, respectively, 200, 320 and 640 A) and voltages of 220 and 380 V AC. The regulator consists of three power blocks assembled on a common frame (according to the number of phases of back-to-back thyristors), a block of current sensors and an automation block. The power blocks use tablet thyristors with coolers made of drawn aluminum profiles. Air cooling is natural. The automation unit is the same for all versions of regulators.

Thyristor regulators are made with a degree of protection IP00 and are intended for installation on standard frames of magnetic controllers of the TTZ type, which are similar in design to controllers of the TA and TCA series. Overall dimensions and weight of PCT series regulators are indicated in table. 1.

Table 1 Dimensions and weight of voltage regulators of the PCT series

The TTZ magnetic controllers are equipped with direction contactors for reversing the motor, rotor circuit contactors and other relay contact elements of the electric drive that communicate between the command controller and the thyristor regulator. The structure of the regulator control system can be seen from the functional diagram of the electric drive shown in Fig. 2.

The three-phase symmetrical thyristor block T is controlled by the SFU phase control system. With the help of the command controller KK in the regulator, the speed setting of the BZS is changed. Through the BZS block, as a function of time, the acceleration contactor KU2 in the rotor circuit is controlled. The difference between the task signals and the TG tachogenerator is amplified by amplifiers U1 and US. A logical relay device is connected to the output of the ultrasonic amplifier, which has two stable states: one corresponds to turning on the forward direction contactor KB, the second corresponds to turning on the reverse direction contactor KN.

Simultaneously with the change in the state of the logical device, the signal in the control circuit control circuit is reversed. The signal from the matching amplifier U2 is summed with the delayed feedback signal for the motor stator current, which comes from the TO current limiting unit and is fed to the input of the SFU.

The BL logic block is also influenced by a signal from the current sensor block DT and the current presence block NT, which prohibits switching of contactors in the direction under current. The BL block also carries out nonlinear correction of the rotation speed stabilization system to ensure the stability of the drive. Regulators can be used in electric drives of lifting and moving mechanisms.

Regulators of the PCT series are made with a current limiting system. The current limiting level for protecting thyristors from overloads and for limiting motor torque in dynamic modes varies smoothly from 0.65 to 1.5 of the rated current of the regulator, the current limiting level for overcurrent protection is from 0.9 to. 2.0 rated current of the regulator. A wide range of changes in protection settings ensures operation of a regulator of the same standard size with motors differing in power by approximately 2 times.

Rice. 2. Functional diagram of an electric drive with a thyristor regulator of the PCT type: KK - command controller; TG - tachogenerator; KN, KB - directional contactors; BZS - speed setting unit; BL - logic block; U1, U2. Ultrasound - amplifiers; SFU - phase control system; DT - current sensor; IT - current availability block; TO - current limiting unit; MT - protection unit; KU1, KU2 - acceleration contactors; CL - linear contactor: R - switch.

Rice. 3. Thyristor voltage regulator PCT

The sensitivity of the current presence system is 5-10 A of the effective value of the current in the phase. The regulator also provides protection: zero, against switching overvoltages, against loss of current in at least one of the phases (IT and MT units), against interference with radio reception. Fast-acting fuses of the PNB 5M type provide protection against short-circuit currents.

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