DIY 220v voltage regulator. How to make a voltage regulator with your own hands. Adjustable voltage regulator circuit

The stabilizer is a mains autotransformer, the winding taps of which are switched automatically depending on the voltage in the mains.

The stabilizer allows you to maintain the output voltage at 220V while changing the input voltage from 180 to 270 V. The stabilization accuracy is 10V.

The schematic diagram can be divided into a low-current circuit (or control circuit) and a high-current circuit (or an autotransformer circuit).

The control circuit is shown in Figure 1. The role of the voltage meter is assigned to a polycomparator microcircuit with linear voltage indication - A1 (LM3914).

The mains voltage is supplied to the primary winding of the low-power transformer T1. This transformer has two secondary windings, 12V each, with one common terminal (or one 24V winding with a center tap).

The rectifier on the VD1 diode is used to obtain the supply voltage. The voltage from the capacitor C1 is fed to the power circuit of the A1 microcircuit and the LEDs of the H1.1-H9.1 optocouplers. And also, it serves to obtain exemplary stable voltages of the minimum and maximum scale marks. To obtain them, a parametric stabilizer is used for US and P1. The limiting values ​​of the measurement are set by the trimming resistors R2 and R3 (resistor R2 is the upper value, the resistor R3 is lower).

The measured voltage is taken from the other secondary winding of the transformer T1. It is rectified by the diode VD2 and fed to the resistor R5. It is by the level of constant voltage across the resistor R5 that the degree of deviation of the mains voltage from the nominal value is assessed. In the process of establishing, the resistor R5 is pre-set in the middle position, and the resistor RЗ in the lower one according to the scheme.

Then, an increased voltage (about 270V) is supplied to the primary winding T1 from the LATR-type autotransformer, and the resistor R2 is used to bring the microcircuit scale to the value at which the LED connected to pin 11 is on (temporarily, instead of the optocoupler LEDs, ordinary LEDs can be connected). Then the input alternating voltage is reduced to 190V and the resistor R3 is scaled to the value when the LED connected to terminal 18 of A1 is on.

If the above settings cannot be made, you need to adjust R5 a little and repeat them again. So, by successive approximations, a result is achieved when a change in the input voltage by 10V corresponds to switching the outputs of the A1 microcircuit.

In total, nine threshold values ​​are obtained, - 270V, 260V, 250V, 240V, 230V, 220V, 210V, 200V, 190V.

The schematic diagram of the autotransformer is shown in Figure 2. It is based on a converted LATR transformer. The transformer case is disassembled and the slide contact is removed, which serves to switch the taps. Then, according to the results of preliminary measurements of the voltages from the taps, conclusions are made (from 180 to 260V with a step of 10V), which are subsequently switched using triac switches VS1-VS9, controlled by the control system through optocouplers H1-H9. The optocouplers are connected so that when the reading of the A1 microcircuit decreases by one division (by 10V), the autotransformer is switched to a step-up (by the next 10V) tap. And vice versa - an increase in the readings of the A1 microcircuit leads to switching to the downward tap of the autotransformer. By selecting the resistance of the resistor R4 (Fig. 1), the current is set through the LEDs of the optocouplers, at which the simistor switches switch confidently. The circuit on transistors VT1 and VT2 (Fig. 1) serves to delay the switching on of the autotransformer load for the time required to complete the transient processes in the circuit after switching on. This circuit delays the connection of the LEDs of the optocouplers to the power supply.

Instead of the LM3914 microcircuit, you cannot use similar LM3915 or LM3916 microcircuits, due to the fact that they work according to the logarithmic law, but here you need a linear one, like in the LM3914. Transformer T1 is a small-sized Chinese transformer of the TLG type, for a primary voltage of 220V and two secondary ones for 12V (12-0-12V) and a current of 300mA. You can use another similar transformer.

Transformer T2 can be made from LATR as described above, or you can wind it yourself.

Voltage swings negatively affect any household appliance. This is especially true of high-precision electronics that regulate the operation of heating devices.

In order to equalize the current at home, a voltage stabilizer is used. In its simplest form, it works on the principle of a rheostat, increasing and decreasing resistance depending on the strength of the current. But there are also more modern devices that fully protect equipment from power surges. How to make them and we'll talk.

Voltage stabilizer and its principle of operation

For a more detailed understanding of the operation of the device, consider the components of the electric current:

• current strength,
• voltage,
• frequency.

The amperage is the amount of charge that has passed through the conductor in a given period of time. Voltage, in a very simple way, is equivalent to the work that an electric field does. Frequency is the rate at which the flow of electrons changes direction. This value is characteristic exclusively for alternating current that circulates in the power grid. Most household appliances are designed for a voltage of 220 volts, while the current strength should be 5 Amperes, and the frequency should be 50 Hertz.

In most cases, household appliances have an acceptable plug for each of the parameters, but any protection is designed so that the operating conditions of the devices will remain unchanged for a long time. In our network, current fluctuations occur almost constantly. The amplitude is up to 2 A in current strength and up to 40-50 V in voltage. The current frequency is also different from 50 Hz and ranges from 40 Hz to 60 Hz.

This problem is associated with many factors, but the main one is the remoteness of the end consumer from the source of electricity. As a result of sufficiently long transportation and multiple transformation, the current loses its stability. This defect in electrical networks is present not only in our country, but also in any other countries that use electricity. Therefore, a special device was invented to stabilize the output current.

Types of voltage stabilizers

Since the current is the directed movement of particles, the following are used to regulate it:

• mechanical method,
• pulse method.

Mechanical is based on Ohm's Law. Such a stabilizer is called linear. It consists of two bends connected by a rheostat. Voltage is applied to one knee, passes through the rheostat and falls on the second knee, from which it is distributed further. The advantages of this method is that it allows you to fairly accurately set the parameters of the output current. Depending on the purpose, the linear stabilizer is upgraded with additional spare parts. It should be noted that the device effectively copes with its task only if the difference between the input and output currents is small. Otherwise, the stabilizer will have low efficiency. But even this is enough to protect household appliances and protect yourself from a short circuit in the event of an overload of the network.

The switching voltage regulator is based on the principle of current amplitude modulation. The voltage regulator circuit is designed in such a way that there is a switch in the circuit that automatically breaks the circuit at regular intervals. This allows you to supply current in parts and evenly accumulate it in the capacitor. After it is charged, the already aligned current is supplied to the devices. The disadvantage of this method is that it does not allow you to set a specific value. However, there are quite often pulse buck-boost regulators that are optimal for domestic use. They equalize the current within the limits slightly below or slightly above the norm. In both cases, all current parameters are within the permissible plug.

It is also important to note the division of devices into:

• single-phase voltage stabilizer,
• three-phase voltage stabilizer.

After redistribution in the transformer, a three-phase line comes out, it usually goes to the switchboard to a separate house. Further from the dashboard to the apartment, there are already standard phases and zero. Thus, most household appliances are designed specifically for a single-phase network. Therefore, in typical apartments, it is advisable to use a single-phase stabilizer. In addition, it costs 10 times cheaper than a three-phase one, even if you assemble it yourself.

Voltage stabilizers for summer cottages can also be three-phase. This is especially true for powerful pumps, cultivators and heavy construction equipment. In this case, it is necessary to make a stabilizer designed to transform the current for a specific device. In practice, this is quite difficult to do. Therefore, it is easier to rent it. The use of the above devices is temporary, so there is no point in wasting time and money on a three-phase voltage stabilizer.

The main elements of the voltage stabilizer

In order to assemble a simple current equalizer, neither special skills nor specific details are required. Home voltage stabilizers consist of:

• transformer,
• capacitors,
• resistors,
• diodes,
• wires for connecting the microcircuit.

Ideal if you have an old welding machine. It is very easy to convert it into a voltage stabilizer; besides, you do not need to buy additional parts and design a case for microcircuits. The video at the end of the article is devoted to this issue. But, unnecessary welding is very rare, so we will consider the procedure for creating a voltage stabilizer from scratch. Since the switching regulator does not allow precise adjustment of the parameters, we will consider a linear voltage regulator.

Making a homemade voltage regulator

Its basis is a transformer. In practice, transformers are much smaller than massive booths to balance the high voltage coming from the power plant. They are two coils that form an inductive electromagnetic coupling. Simply put, the current is supplied to one coil, charges it, then an electromagnetic field arises, which charges the second coil, from which the current flows further. This relationship is expressed by the formula:

U 2	=	N 2	=	I 1
U 1		N 1		I 2

• U 1 - voltage on the primary winding,
• U 2 - voltage on the secondary winding,
• N 1 - the number of turns on the primary winding,
• N 2 - the number of turns on the secondary winding,
• I 1 - current on the primary winding,
• I 2 - current on the secondary winding.

The formula is not perfect, as it allows you to either lower the voltage or increase it. In 90% of cases, a low voltage current reaches the consumer. Therefore, it makes sense to immediately make a step-up transformer. Inductive coils for it are sold in electrical stores or at any flea market. It is important to note that the number of turns must be at least 2000 thousand, otherwise the transformer will get very hot and will soon burn out. In order to select the power of the transformer, it is necessary to measure the voltage in the network. For calculations, we take the value of 196 V. The formula takes the following form:

As you can see from the formula, the voltage at the output will be 220x4 / 196 = 4.4 A. Most electrical appliances allow a plug of 1 A. Therefore, the resulting value is sufficient for the normal operation of equipment.

Voltage stabilizer, the energy in which increases by a predetermined amount is ready. But, if a power surge occurs in the network, then the formula will take the following values:

This will damage most electrical appliances.

To eliminate this defect, we will use Ohm's law:

• U - voltage,
• I - current strength,
• R - resistance.

264 = 4.47xR, R = 264 / 4.47 = 60. This formula says that, ideally, the resistance of all elements in the system will be 60 ohms. If you lower the resistance, then the voltage will decrease:

220 = 4.47xR, R = 220 / 4.47 = 50.

To change the resistance of the network, a device called a rheostat is used. Naturally, it is rather inconvenient to adjust it manually. Therefore, you will need a voltage stabilizer microcircuit, on which the path of the electric current after leaving the transformer will be marked.

The easiest way is to transfer the current from the transformer to the capacitor. It is advisable to use 12-16 capacitors of the same capacity. This will accumulate the current and make it more uniform. Further, all capacitors are connected to a rheostat. The current in the network after the transformer will be in the range of 4.5-5 A, and the desired voltage should be 220 V. Therefore, we have the formula R = 220 / 4.75 = 46. With average values, the resistance should be 46 ohms.

To achieve a smoother alignment, it is advisable to install several parallel rheostats. Thus, connecting into one stream after the capacitors, the circuit must be distributed into 4,6,8 separate branches connected to rheostats. In this case, the formula R / number of rheostats should be used. If you make a circuit of 6 rheostats, then according to the data presented, each of them should have a resistance of 8 ohms.

After passing the rheostats, the circuit is again assembled into one stream and output to the diode. The diode is connected to a regular outlet.

All these manipulations refer to the wire on which the phase is located, we simply pass zero directly to the outlet.

The method indicated with rheostats is rather archaic. It is much more efficient to use a conventional residual current device instead. The current from the transformer is supplied to the RCD, zero is also connected to the RCD. Further from it goes directly to the outlet.

In the event that the voltage or current strength increases as a result of a voltage surge, the RCD will open the circuit, and household appliances will not be damaged. The rest of the time, the transformer will qualitatively equalize the current.

With increased voltage, a step-down transformer is required. It is assembled by analogy, with the exception that the winding on the second coil must be made of thicker wire, otherwise the transformer will burn out.

It is most efficient to assemble both transformers. Moreover, there are buck-boost designs. In the first case, you will need to manually switch the wire, in the second, the process is amenable to automation. As you can see, making a voltage regulator is not difficult, but working with electricity involves the utmost level of caution.

Tips for working with a homemade voltage regulator

Important: the described scheme is ideal for constant conditions, but interruptions and surges occur in the mains quite often, both up and down.

Therefore, when assembling a voltage stabilizer, we recommend building on the parameters of a specific technique, i.e.:

• think over the layout of the apartment,
• if no repair is expected, install extension cords for certain groups of electrical appliances with similar parameters,
• connect each group to a separate stabilizer.

Any household appliances either on the back side or in the passport contains statements of power requirements. Based on specific numbers, it is much easier to create an effective stabilizer, since there is no need to adapt to the network. Another useful gadget is an electronic voltmeter. It is advisable to connect it to the stabilizer circuit for visual control over its operation.

Any material other than wood is suitable for the body. It is not uncommon for homemade stabilizers to be placed in plastic food containers.

Modern life is associated with the constant use of various techniques, and some areas are simply unthinkable without it. Naturally, everyone wants the service life of such devices to be maximized, some for this purpose buy only products of well-known brands for greater reliability. However, the high cost does not always guarantee safety under critical operating conditions. These include sudden drops in mains voltage. This is especially true for the category of household appliances that implies a permanent network connection, for example, a refrigerator.

In order to protect yourself from the unpleasant consequences of such voltage surges, you can acquire a special technical device that stabilizes the output current. Two methods are used to adjust the voltage:

1. Mechanical. For this method, a linear stabilizer is used, consisting of 2 elbows and a rheostat connecting them. Voltage is supplied to the first knee and is transmitted through the rheostat to the second, which distributes the flow further. This method is effective in conditions of a small difference between the input and output currents; in other cases, the efficiency decreases.

2. Pulse. The design of the stabilizer includes a switch that periodically breaks the circuit for a certain time. This makes it possible to supply current in portions and accumulate it evenly in the capacitor. After the capacitor is fully charged, an equalized flow is supplied to the devices without surges.

The main disadvantage of this method is the inability to set a specific parameter value. Therefore, if you decide to assemble a 220V voltage regulator with your own hands, you need to focus on the mechanical method. To create a simple linear single-phase current equalizer you will need:

• Transformer;
• Capacitors;
• Resistors;
• Diode;
• The wires that will connect the microcircuits.

A transformer is a pair of coils that form an inductive electromagnetic coupling, i.e. getting on the primary winding, the current charges it, and the resulting electromagnetic field charges another coil. This relationship between voltage (U), current (I) and the number of turns (N) on both windings is expressed by the formula:

I2 / I1 = N2 / N1 = U2 / U1

Inductive coils themselves can be found in every electrical store. The number of turns on the first should not be less than 2000. Having measured the voltage in the network, you can calculate the required number of turns on the secondary winding. For example, the actual voltage is 198V, then the second coil should have x / 2000 = 220/198 = 2223 turns. The generated current is determined by the same principle. According to this scheme, with a sharp increase in the input power, the voltage will proportionally increase at the output. Therefore, to regulate such situations, a rheostat is needed that changes the resistance of the network. The path followed by the current after the transformer is marked on the stabilizer microcircuit.

From the transformer, the current is output to capacitors of the same capacity to accumulate and equalize the flux, about 16 of them will be required. Next, the capacitors must be connected to the rheostat. Its resistance at a voltage of 220 V and a current of 4.75 A (average value of the range 4.5-5 A) after the transformer should be 46 ohms. For the most smooth voltage equalization, you can install several rheostats, distributing the resistance equally to each. After the circuit passes the rheostats, it is again connected into a single stream and follows to the diode, which is connected directly to the outlet.

These operations apply to a wire with a phase, zero is directly passed to the outlet. These stabilizers are best suited to constant voltage conditions and are assembled according to the parameters of a particular device, which significantly increases the efficiency of the device.

The difference between the supplied voltage and the reference 220 V may be due to both the quality of the transformers and wires, and the remoteness of the consumer from the distribution device. Also, one of the important factors affecting voltage stability is physical wear and tear and overloading of power lines. All this leads to drawdowns and voltage surges, which negatively affects all electrical appliances without exception.

220V voltage regulators solve this problem. The scheme of such devices allows you to smooth out surges in the network, and to receive stable 220 volts at the output with a small permissible error. At the same time, it is not necessary to buy such a device - if desired and with minimal knowledge of circuitry, you can assemble it yourself at home.

Varieties of stabilizers

All industrial designs of such equipment can be divided into two large groups:

• electromechanical;
• impulse.

Electromechanical

The operation of electromechanical devices is based on a servo drive, which is able to change the number of winding turns (and hence the output voltage) by moving the conductive slider along the rheostat. Such devices are cheaper than all other models, and have very good stabilization indicators. However, they are more likely to break due to the presence of many mechanical parts.

But their most important disadvantage is the response speed. Due to the fact that the drive does not move the collector instantaneously, the stabilization delay can be up to 0.1 seconds, which is catastrophically long for devices that are sensitive to differences. In other words, such a stabilizer may simply not have time to protect modern electronics. In addition, due to the presence of mechanical parts, it is not a trivial task to reproduce such a device at home.

Impulse

Pulse stabilizers are called stabilizers, the operation of which is based on the principle of accumulating current, and issuing it to the consumer in fragments - impulses. These time intervals allow the system to accumulate the required current in, and then issue a stabilized power supply. Such devices include devices whose operation is based on triacs and thyristors.

Such devices are more expensive than their electromechanical counterparts, but also much more reliable - there are no rubbing and moving parts, which means that there is essentially nothing to break. True, their stabilization indicators are worse - they are only capable of a proportional increase or decrease in the incoming indicators. But the response speed is up to 20 milliseconds, and this is enough to secure even the most sensitive household electrical appliances. In addition, such a device can be assembled with your own hands, having the necessary skill and element base.

In addition to the separation according to the stabilization principle, there is a division into single and three-phase devices. But in view of the fact that single-phase power is usually used at home, we do not take three-phase devices into account.

Voltage regulator circuit for 220 V

In the circuit, which we will consider as an example of creating a stabilizer with our own hands, triacs are used. Thanks to a well-chosen element base, this device will be able to provide stable performance when supplied to it from 130 to 270 V, and will withstand connecting a load of up to 6 kW to it. But most importantly, the response speed is about 10 ms! Here is the diagram of the future voltage regulator for 220 V:

Despite the seeming complexity of the 220 V voltage regulator circuit, there should be no problems in the production of such a device with your own hands, if you have at least basic knowledge of electrical engineering. So, the list of components required for a successful assembly:

• Power Supply;
• Rectifier (correcting voltage amplitude);
• Controller and comparator;
• Amplifier stage;
• Load turn-on delay device;
• Automatic transformer;
• Keys;
• Switch with fuse function.

You will also need wires to connect elements and winding transformers, a printed circuit board for assembling the circuit, and from tools - a soldering iron, solder and tweezers.

DIY 220 V stabilizer manufacturing process

First you need to take a piece of foil-clad textolite that is suitable in size (approximately 120 × 90 mm) for making a printed circuit board. The circuit itself can be transferred to a plane using an iron and a schematic diagram printed on paper:

Having received the necessary architecture, you can start winding transformers (you can buy ready-made TPK-2-2, for 12V and connect them in series, but you can make it yourself). To wind each trance, you will need a magnetic core with a cross section of 1.87 cm 2 and three wires. The first winding is 8669 turns of wire with a cross section of 0.064 mm. The other two windings are already made with a wire with a cross-sectional area of ​​0.185 mm, and each of them will contain 522 turns.

The second transformer is different - it is assembled on a toroidal magnetic circuit, but the number of turns will already be 455. The second transformer block should contain 7 taps, and if 3mm 2 wire is enough for the first three, then for the rest it is necessary to use a bus with a cross-sectional area of ​​at least 18 mm 2. This will avoid heat build-up during operation of the device and improve overall safety.

After assembling the transformers, they must be connected in series according to the diagram below:

The rest of the components for the assembly need to be bought. Having purchased everything you need, you can start assembling the device according to the schematic electrical diagram. It is important to remember that the controller microcircuit and triacs must be mounted on a cooling radiator using thermally conductive paste or glue.

By bringing all the elements together, you will receive a reliable and high-quality device with characteristics that will satisfy all the household needs of an ordinary residential building.

If such a scheme is difficult for you, it is better to choose another version of a homemade stabilizer, for example, a relay type. The circuit of such a 220 V stabilizer is not as complicated as that of the triac version, and it is usually cited as an example in all magazines for radio amateurs:

The circuit is simple, and contains 3 stabilization blocks, with different voltage thresholds. Each of them consists of a zener diode and resistors. In addition to the blocks, the circuit has two transistor switches that control electromagnetic relays. Due to its simplicity and relative reliability, such a device will be an excellent alternative to more complex devices.

Pros and cons of a homemade stabilizer

Among the positive aspects of such a device, it is worth noting:

• Quite high stabilization rates, sufficient for domestic needs;
• Low price in comparison with factory devices;
• Self-repair availability.

However, in addition to the advantages, such a stabilizer will also have a number of disadvantages:

• Do-it-yourself assembly is inferior in quality to the factory one (soldering, winding transformers, etc.);
• Complex and painstaking setting of the finished device;
• The inability to obtain accurate stabilization data due to the lack of special equipment.

In conclusion, I would like to say that in the absence of at least initial skills in circuitry and experience in soldering radio components, it is not worth taking on the assembly of such a device, since this is a responsible and important node in the electrical network of the house, on which the safety of all electrical appliances depends.

Basic data on the design of the voltage regulator is in this video:

Often for safe use, such as a TV, usually in rural areas, a single-phase voltage stabilizer 220V, which, with a strong decrease in voltage in the mains, gives out at its output a nominal output voltage of 220 volts.

In addition, when operating most types of household electronic equipment, it is desirable to use a voltage stabilizer that does not create changes in the output voltage sine wave. Diagrams of similar stabilizers for 220 volts are given in many magazines on electronics.

In this article, we will give an example of one of the options for such a device. The stabilizer circuit, depending on the actual voltage in the network, has 4 ranges for automatic setting of the output voltage. This contributed to a significant expansion of the stabilization limits 160 ... 250 volts. And with all this, the output voltage is provided within the normal range (220V +/- 5%).

Description of the operation of a single-phase voltage stabilizer 220 volts

The electrical circuit of the device includes 3 threshold blocks, made according to the principle, consisting of a zener diode and resistors (R2-VD1-R1, VD5-R3-R6, R5-VD6-R6). Also in the circuit there are 2 transistor keys VT1 and VT2, which control the electromagnetic relays K1 and K2.

Diodes VD2 and VD3 and filter capacitor C2 form a constant voltage source for the entire circuit. Capacities C1 and C3 are designed to extinguish minor voltage surges in the network. Capacitor C4 and resistance R4 are “spark extinguishing” elements. To prevent self-induction voltage surges, two diodes VD4 and VD7 are added to the circuit in the relay windings when they are turned off.

With perfect operation of the transformer and threshold units, each of the 4 control ranges would create a voltage range from 198 to 231 volts, and the probable mains voltage could be in the region from 140… 260 volts.

Nevertheless, in reality, it is necessary to take into account the spread of the parameters of radio components and the instability of the transformation ratio of the transformer at different loads. In this regard, for all 3 threshold units, the output voltage range is reduced in relation to the output voltage: 215 ± 10 volts. Accordingly, the range of fluctuations at the input has also narrowed to 160 ... 250 volts.

Stages of the stabilizer:

1. When the voltage in the mains is less than 185 volts, the voltage at the output of the rectifier is low in order for one of the threshold units to work. At this moment, the contact groups of both relays are located, as indicated in the circuit diagram. The voltage across the load is equal to the mains voltage plus the voltage boost taken from the windings II and III of the transformer T1.

2. If the voltage in the network is in the range of 185 ... 205 volts, then the VD5 Zener diode is in the open state. The current flows through relay K1, Zener diode VD5 and resistances R3 and R6. This current is not enough for relay K1 to work. Due to the voltage drop across R6, the transistor VT2 opens. This transistor, in turn, turns on the relay K2 and the contact group K2.1 switches the winding II (voltage boost)

3. If the voltage in the network is in the range of 205 ... 225 volts, then the Zener diode VD1 is already in the open state. This leads to the opening of the transistor VT1, because of this, the second threshold unit is turned off and, accordingly, the transistor VT2. Relay K2 is disconnected. At the same time, relay K1 and contact group K1.1 are switched on. moves to another position, in which the windings II and III are not involved and therefore the voltage at the output will be the same as at the input.

4. If the voltage in the network is in the range of 225 ... 245 volts, the VD6 zener diode opens. This contributes to the activation of the third threshold unit, which leads to the opening of both transistor switches. Both relays are on. Now the winding III of the transformer T1 is connected to the load, but in antiphase with the mains voltage (“negative” voltage boost). The output in this case will also have a voltage in the region of 205 ... 225 volts.

When setting the regulation range, you need to carefully select the zener diodes, since, as you know, they can differ significantly in the spread of the stabilization voltage.

Instead of KS218ZH (VD5), it is possible to use KS220Zh zener diodes. This zener diode must certainly be with two anodes, because in the range of the mains voltage 225 ... 245 volts, when the VD6 zener diode opens, both transistors open, the R3 - VD5 circuit shunts the resistance R6 of the threshold block R5-VD6-R6. To eliminate the shunting effect, the VD5 Zener diode must be with two anodes.

Zener diode VD5 for a voltage of no more than 20V. Zener diode VD1 - KS220Zh (22 V); it is possible to assemble a chain of two zener diodes - D811 and D810. Zener diode KS222ZH (VD6) 24 volts. It can be exchanged for a chain of D813 and D810 zener diodes. Transistors from the series. Relays K1 and K2 - REN34, passport HP4.500.000-01.

The transformer is assembled on an OL50 / 80-25 magnetic core made of E360 (or E350) steel. The tape is 0.08 mm thick. Winding I - 2400 turns wound with wire PETV-2 0.355 (for a rated voltage of 220V). Windings II and III are equal, each containing 300 turns of wire PETV-2 0.9 (13.9 V).

It is necessary to adjust the stabilizer when the load is connected, so that the load on the transformer T1 is taken into account.