Simple self-oscillating voltage converters using transistors. High power step-up transformer voltage converters Small-sized network voltage converter

Of course, this device is extremely primitive and is more of a workout for the mind. For more stable operation, it needs to be supplemented with a simple control circuit that maintains the shutdown threshold much more accurately:

Schematic diagrams of simple voltage converters based on self-oscillators are built using transistors.

Self-excited generators (self-oscillators) usually use positive feedback to excite electrical oscillations. There are also self-oscillators based on active elements with negative dynamic resistance, but they are practically not used as converters.

Single-stage voltage converters

The simplest circuit of a single-stage voltage converter based on a self-oscillator is shown in Fig. 1. This type of generators is called blocking generators. The phase shift to ensure the conditions for the occurrence of oscillations in it is ensured by a certain inclusion of the windings.

Rice. 1. Diagram of a voltage converter with transformer feedback.

An analogue of the 2N3055 transistor is KT819GM. The blocking generator allows you to receive short pulses with a large duty cycle. The shape of these pulses is close to rectangular.

The capacitances of the oscillatory circuits of the blocking generator are, as a rule, small and are determined by the interturn capacitances and the mounting capacitance. The maximum generation frequency of the blocking oscillator is hundreds of kHz. The disadvantage of this type of generator is the pronounced dependence of the generation frequency on changes in the supply voltage.

The resistive divider in the base circuit of the converter transistor (Fig. 1) is designed to create an initial bias. A slightly modified version of the converter with transformer feedback is shown in Fig. 2.

Rice. 2. Diagram of the main (intermediate) block of a high-voltage voltage source based on a self-oscillating converter.

The self-oscillator operates at a frequency of approximately 30 kHz. At the output of the converter, a voltage with an amplitude of up to 1 kV is generated (determined by the number of turns of the step-up winding of the transformer).

Transformer T1 is made on a dielectric frame inserted into an armored core B26 made of M2000NM1 (M1500NM1) ferrite. The primary winding contains 6 turns; secondary winding - 20 turns of PELSHO wire with a diameter of 0.18 mm (0.12...0.23 mm).

The step-up winding to achieve an output voltage of 700...800 V has approximately 1800 turns of PEL wire with a diameter of 0.1 mm. Every 400 turns during winding, a dielectric pad made of capacitor paper is laid, the layers are impregnated with capacitor or transformer oil. The coil terminals are filled with paraffin.

This converter can be used as an intermediate converter to power subsequent stages of high voltage generation (for example, with electric dischargers or thyristors).

The next voltage converter (USA) is also made on a single transistor (Fig. 3). Stabilization of the base bias voltage is carried out by three series-connected diodes VD1 - VD3 (forward bias).

Rice. 3. Diagram of a voltage converter with transformer feedback.

The collector junction of transistor VT1 is protected by capacitor C2, in addition, a chain of diode VD4 and zener diode VD5 is connected in parallel to the collector winding of transformer T1.

The generator produces pulses that are close to rectangular in shape. The generation frequency is 10 kHz and is determined by the capacitance value of the capacitor SZ. An analogue of the 2N3700 transistor is KT630A.

Push-pull voltage converters

The circuit of a push-pull transformer voltage converter is shown in Fig. 4. Analogue of transistor 2N3055 - KT819GM. The transformer of a high-voltage converter (Fig. 4) can be made using a ferrite open core of round or rectangular cross-section, as well as based on a television line transformer.

When using a round ferrite core with a diameter of 8 mm, the number of turns of the high-voltage winding, depending on the required output voltage, can reach 8000 turns of wire with a diameter of 0.15...0.25 mm. The collector windings contain 14 turns of wire with a diameter of 0.5...0.8 mm.

Rice. 4. Scheme of a push-pull converter with transformer feedback.

Rice. 5. A variant of the high-voltage converter circuit with transformer feedback.

The feedback windings (base windings) contain 6 turns of the same wire. When connecting the windings, their phasing must be observed. The output voltage of the converter is up to 8 kV.

Domestic-made transistors, for example, KT819 and the like, can be used as converter transistors.

A variant of the circuit of a similar voltage converter is shown in Fig. 5. The main difference lies in the bias supply circuits to the bases of the transistors.

The number of turns of the primary (collector) winding is 2x5 turns with a diameter of 1.29 mm, the secondary - 2x2 turns with a diameter of 0.64 mm. The output voltage of the converter is entirely determined by the number of turns of the boost winding and can reach 10...30 kV.

A. Chaplygin's voltage converter does not contain resistors (Fig. 6). It is powered by a 5 6 battery and is capable of delivering up to 1 A to the load at a voltage of 12 V.

Rice. 6. Circuit diagram of a simple high-efficiency voltage converter powered by a 5V battery.

The rectifier diodes are the junctions of the oscillator transistors. The device can also operate at a supply voltage reduced to 1 V.

For low-power converter options, you can use transistors like KT208, KT209, KT501 and others. The maximum load current should not exceed the maximum base current of the transistors.

Diodes VD1 and VD2 are optional, but they allow you to obtain an additional voltage of 4.2 V of negative polarity at the output. The efficiency of the device is about 85%. Transformer T1 is made on a K18x8x5 2000NM1 ring. Windings I and II each have 6, III and IV each have 10 turns of PEL-2 0.5 wire.

Three-point inductive converter

The voltage converter (Fig. 7) is made according to an inductive three-point circuit and is intended for measuring high-resistance resistances and allows you to obtain an unstabilized voltage of 120... 150 V at the output.

The current consumed by the converter is about 3...5 mA at a supply voltage of 4.5 V. The transformer for this device can be created on the basis of the BTK-70 television transformer.

Rice. 7. Diagram of a voltage converter based on an inductive three-ton circuit.

Its secondary winding is removed, and in its place a low-voltage winding of the converter is wound - 90 turns (two layers of 45 turns each) of PEV-1 wire 0.19...0.23 mm. Branch from the 70th turn from below according to the diagram. Resistor R1 is 12...51 kOhm.

Voltage converter 1.5 V/-9 V

Rice. 8. 1.5 V/-9 V voltage converter circuit.

The converter (Fig. 8) is a single-cycle relaxation generator with capacitive positive feedback (C2, SZ). The collector circuit of transistor VT2 includes a step-up autotransformer T1.

The converter uses reverse connection of the rectifying diode VD1, i.e. when transistor VT2 is open, supply voltage Un is applied to the winding of the autotransformer, and a voltage pulse appears at the output of the autotransformer. However, the diode VD1, turned on in the reverse direction, is closed at this time, and the load is disconnected from the converter.

At the moment of pause, when the transistor closes, the polarity of the voltage on the windings T1 is reversed, the diode VD1 opens, and the rectified voltage is applied to the load.

In subsequent cycles, when transistor VT2 is turned off, the filter capacitors (C4, C5) are discharged through the load, allowing direct current to flow. In this case, the inductance of the step-up winding of the autotransformer T1 plays the role of a smoothing filter choke.

To eliminate the magnetization of the autotransformer core by the direct current of transistor VT2, magnetization reversal of the autotransformer core is used by connecting capacitors C2 and S3 in parallel with its winding, which are also a feedback voltage divider.

When transistor VT2 closes, capacitors C2 and SZ are discharged through part of the transformer winding during a pause, reversing the magnetization of core T1 with the discharge current.

The generation frequency depends on the voltage at the base of the transistor VT1. Stabilization of the output voltage is carried out due to negative feedback (NFB) for constant voltage through R2.

As the output voltage decreases, the frequency of the generated pulses increases with approximately the same duration. As a result, the frequency of recharging filter capacitors C4 and C5 increases and the voltage drop across the load is compensated. As the output voltage increases, the generation frequency, on the contrary, decreases.

So, after charging the storage capacitor C5, the generation frequency drops tens of times. Only rare pulses remain, compensating for the discharge of capacitors in rest mode. This stabilization method made it possible to reduce the quiescent current of the converter to 0.5 mA.

Transistors VT1 and VT2 should have the highest possible gain to increase efficiency. The winding of the autotransformer is wound on a K10x6x2 ferrite ring made of 2000NM material and has 300 turns of PEL-0.08 wire with a tap from the 50th turn (counting from the “grounded” terminal). Diode VD1 must be high-frequency and have low reverse current. Setting up the converter comes down to setting the output voltage to -9 V by selecting resistor R2.

Voltage converter with PWM control

In Fig. Figure 9 shows a circuit of a stabilized voltage converter with pulse-width control. The converter remains operational when the battery voltage decreases from 9.... 12 to 3V. Such a converter turns out to be most suitable for battery-powered equipment.

Stabilizer efficiency is at least 70%. Stabilization is maintained when the power supply voltage is reduced below the stabilized output voltage of the converter, which a traditional voltage stabilizer cannot provide. The principle of stabilization used in this voltage converter.

Rice. 9. Diagram of a stabilized voltage converter with PWM control.

When the converter is turned on, the current through resistor R1 opens transistor VT1, the collector current of which, flowing through winding II of transformer T1, opens powerful transistor VT2. Transistor VT2 enters saturation mode, and the current through winding I of the transformer increases linearly.

Energy is stored in the transformer. After some time, transistor VT2 switches to active mode, and a self-inductive emf appears in the transformer windings, the polarity of which is opposite to the voltage applied to them (the magnetic circuit of the transformer is not saturated).

Transistor VT2 closes like an avalanche and the self-inductive emf of winding I charges capacitor S3 through diode VD2. Capacitor C2 promotes more precise closing of the transistor. Then the process is repeated.

After some time, the voltage on the capacitor SZ increases so much that the zener diode VD1 opens, and the base current of the transistor VT1 decreases, while the base current decreases, and therefore the collector current of the transistor VT2.

Since the energy accumulated in the transformer is determined by the collector current of the transistor VT2, further increase in the voltage on the capacitor SZ stops. The capacitor is discharged through the load. Thus, a constant voltage is maintained at the output of the converter. The output voltage is set by the zener diode VD1. The conversion frequency varies within 20... 140 kHz.

Voltage converter 3-12V/+15V, -15V

Voltage converter, the circuit of which is shown in Fig. 10, differs in that in it the load circuit is galvanically isolated from the control circuit. This allows you to obtain several secondary stable voltages. The use of an integrating link in the feedback circuit improves the stabilization of the secondary voltage.

Rice. 10. Circuit of a stabilized voltage converter with a bipolar output 15+15V.

The conversion frequency decreases almost linearly as the supply voltage decreases. This circumstance enhances the feedback in the converter and increases the stability of the secondary voltage.

The voltage on the smoothing capacitors of the secondary circuits depends on the energy of the pulses received from the transformer. The presence of resistor R2 makes the voltage on storage capacitor C3 dependent on the pulse repetition rate, and the degree of dependence (slope) is determined by the resistance of this resistor.

Thus, using the trimming resistor R2, you can set the desired dependence of the change in the voltage of the secondary windings on the change in the supply voltage. Field effect transistor VT2 is a current stabilizer. The efficiency of the converter can reach 70... 90%.

The instability of the output voltage at a supply voltage of 4... 12 V is no more than 0.5%, and when the ambient temperature changes from -40 to +50 ° C - no more than 1.5%. Maximum load power is 2 W.

When setting up the converter, resistors R1 and R2 are set to the minimum resistance position and equivalent loads RH are connected. A supply voltage of 12 V is supplied to the input of the device and, using resistor R1, a voltage of 15 V is set across the load Rн. Next, the supply voltage is reduced to 4 V and resistor R2 is used to achieve an output voltage of 15 V. By repeating this process several times, a stable output voltage is achieved.

Windings I and II and the magnetic circuit of the transformer are the same for both converter options. The windings are wound on an armored magnetic core B26 made of 1500NM ferrite. Winding I contains 8 turns of PEL wire 0.8, and Winding II contains 6 turns of PEL wire 0.33 (each of windings III and IV consists of 15 turns of PEL wire 0.33 mm).

Small-sized network voltage converter

The diagram of a simple small-sized mains voltage converter made from available elements is shown in Fig. 11. The device is based on a conventional blocking generator based on transistor VT1 (KT604, KT605A, KT940).

Rice. 11. Scheme of a step-down voltage converter based on a blocking generator.

The T1 transformer is wound on a B22 armored core made of M2000NN ferrite. Windings Ia and Ib contain 150+120 turns of PELSHO wire 0.1 mm. Winding II has 40 turns of PEL wire 0.27 mm III - 11 turns of PELSHO wire 0.1 mm. First, winding Ia is wound, then II, then winding lb, and finally winding III.

The power supply is not afraid of a short circuit or break in the load, but it has a high voltage ripple coefficient, low efficiency, low output power (up to 1 W) and a significant level of electromagnetic interference. The converter can also be powered from a direct current source with a voltage of 120 6. In this case, resistors R1 and R2 (as well as diode VD1) should be excluded from the circuit.

Low current voltage converter 440V

A low-current voltage converter to power a gas-discharge Geiger-Muller counter can be assembled according to the circuit in Fig. 12. The converter is a transistor blocking generator with an additional boost winding. Pulses from this winding charge the capacitor SZ through rectifier diodes VD2, VD3 to a voltage of 440 V.

The SZ capacitor must be either mica or ceramic, with an operating voltage of at least 500 V. The duration of the blocking generator pulses is approximately 10 μs. The pulse repetition rate (tens of Hz) depends on the time constant of the circuit R1, C2.

Rice. 12. Circuit of a low-current voltage converter for powering a gas-discharge Geiger-Muller counter.

The magnetic core of the T1 transformer is made of two K16x10x4.5 3000NM ferrite rings glued together and is insulated with a layer of varnished cloth, Teflon or fluoroplastic.

First, winding III is wound in bulk - 420 turns of PEV-2 0.07 wire, filling the magnetic circuit evenly. A layer of insulation is placed on top of winding III. Windings I (8 turns) and II (3 turns) are wound with any wire over this layer; they should also be distributed as evenly as possible around the ring.

You should pay attention to the correct phasing of the windings; it must be done before the first turn on. With a load resistance of the order of several MOhms, the converter consumes a current of 0.4... 1.0 mA.

Voltage converter for powering the flash

The voltage converter (Fig. 13) is designed to power the flash. Transformer T1 is made on a magnetic core of two K40x28x6 permalloy rings folded together. The collector circuit winding of transistor VT1 has 16 turns PEV-2 0.6 mm; its base circuit is 12 turns of the same wire. The step-up winding contains 400 turns of PEV-2 0.2.

Rice. 13. Voltage converter circuit for photo flash.

The HL1 neon lamp is used from the fluorescent lamp starter. The output voltage of the converter smoothly increases across the flash capacitor to 200 V in 50 seconds. The device consumes current up to 0.6 A.

Voltage converter PN-70

The PN-70 voltage converter, which is the basis of the device described below, is designed to power flash lamps (Fig. 14). Typically, inverter battery energy is used with minimal efficiency.

Regardless of the frequency of light flashes, the generator operates continuously, consuming a large amount of energy and discharging the batteries.

Rice. 14. Scheme of the modified voltage converter PN-70.

O. Panchik succeeded in switching the converter to standby mode by turning on the resistive divider R5, R6 at the converter output and sending a signal from it through the zener diode VD1 to an electronic switch made on transistors VT1 - VTZ according to the Darlington circuit.

As soon as the voltage on the flash capacitor (not shown in the diagram) reaches the nominal value determined by the value of resistor R6, the zener diode VD1 will break through, and the transistor switch will disconnect the power battery (9 V) from the converter.

When the voltage at the output of the converter decreases as a result of self-discharge or capacitor discharge to the flash lamp, the zener diode VD1 will stop conducting current, the switch and, accordingly, the converter will turn on. Transistor VT1 must be installed on a copper radiator with dimensions of 50x22x0.5 mm.

Step-up transformer voltage converters using transistors are widely used in non-stationary and field conditions to replace the 220 V 50 Hz network to power network equipment and devices.

Such converters must provide output power from units to hundreds of watts when powered by batteries or DC generators with voltages from 6 to 24 V.

Typically, self-generating converters or transformer converters with external excitation are used as high-voltage voltage converters.

An example of a push-pull transformer self-oscillator that converts a direct voltage of 12 B to an alternating voltage of 220 V is shown in Fig. 10.1. The converter operates at an increased conversion frequency - 500 Hz (under load) and 700 Hz at idle. The converter efficiency is about 75%. Such a converter can be used mainly to power an active load, for example, a soldering iron or a lighting lamp. Its output power is up to 40 W.

Resistor R1 is the base current limiter. Circuit R2, C1 creates a triggering current pulse at the moment the generator power is turned on. Choke L1 DPM-0.4 reduces the likelihood of self-excitation of the converter at a higher frequency (more than 10 kHz).

For transformer T1, the magnetic core of a vertical scanning transformer (TVK) is used. All its windings are rewound. Windings I and II contain 30 turns of wire PEV 0.6...0.8. Winding III contains 20 turns of wire PEV 0.16...0.2; winding IV - 1000 turns of the same wire. Windings I and II are wound simultaneously in two wires turn to turn. Winding III

Rice. 10.1. Medium power voltage converter circuit

Rice. 10.2. Power voltage converter circuit

the coil is also wound round to round. Winding IV - piled evenly over the frame.

A step-up transformer battery voltage converter (Fig. 10.2) allows you to obtain an output voltage of 220 V 50 Hz, consuming a current of 5A[^ 0.2] at a voltage of 12 V.

The device is based on a master generator of rectangular pulses, made according to a multivibrator circuit, a typical circuit of which was shown earlier in Fig. 1.1. The operating frequency of this generator should be 50 Hz. Since the output power of the master oscillator is small, two-stage power amplifiers are connected to the outputs of the multivibrator, allowing for a power gain of up to 1000 times.

The low-frequency step-up transformer T1 is turned on at the amplifier output. Diodes VD1 and VD2 protect the output transistors of the converter when they operate on an inductive load.

As transformer T1, you can use unified transformers such as TAN or G/7/7. Transistors VT1 and VT4 can be replaced with KT819GM ​​(with radiators); VT2 and VT3 - KT814, KT816, KT837; diodes VD1 and VD2 - D226.

A 12 B DC to 220 V AC converter (Fig. 10.3) can provide an output power of 100 Bt. The maximum output power of the converter is 100 W, efficiency is up to 50%.

Rice. 10.4. Simple voltage converter circuit

The master oscillator is made according to the circuit of a traditional symmetrical multivibrator, made on transistors VT2 and VT3 (KT815). The output stages of the converter are assembled using composite transistors VT1 and VT4 (KT825). These transistors are installed without insulating gaskets on a common radiator.

The device consumes current from the battery up to 20 L.

A ready-made 100 W network transformer was used as a power transformer (the cross section of the central part of the iron core is about 10 cm^). It must have two secondary windings, rated for 8 B/10 L each.

In order for the operating frequency of the master oscillator to be equal to 50 Hz, the values ​​of resistors R3 and R4 are selected.

The high-power voltage converter operates from a rechargeable battery (Fig. 10.5) and allows you to obtain an output alternating voltage of 220 V with a frequency of 50 Hz. The load power can reach 200 W.

Transformer T1 is wound on a tape magnetic core ШЛ12х20. The primary winding contains 500 turns PEV-2 0.21, tapped from the middle. The control windings have 30 turns of the same wire with a diameter of 0.4 mm.

Transformer T2 is also on a tape magnetic core ШЛ32х38. The primary winding contains 96 turns of PEV-2 2.5 wire, tapped from the middle. The secondary winding has 920 turns of PEV-2 wire with a diameter of 0.56 mm.

The output transistors are installed on radiators with an area of ​​200 cm^. High-current conductors must have a cross-section of at least 4 mm^.

The operation of the converter was tested using a 6ST60 battery.

The following device is designed to power an electric razor from a car on-board network with a constant voltage of 12 V (Fig. 10.6). It consumes a current of about 2.5 V4 under load.

In the converter, the master oscillator on trigger DD1.1 produces a frequency of 100 Hz. Then the frequency divider on the DDI.2 trigger reduces it by 2 times, and the pre-amplifier on transistors VT1, VT2 swings the power amplifier on transistors VT3, VT4, loaded on transformer T1. The master oscillator has a frequency stability of no worse than 5% when the supply voltage changes from 6 to 15 S. The frequency divider simultaneously plays the role of a balun, making it possible to improve the shape of the converter's output voltage. The DDI chip K561TM2 (564TM2) and the pre-amplifier transistors are powered through filter R9, SZ and C4. The secondary winding of transformer T1 with capacitor C5 and the load form an oscillatory circuit with a resonant frequency of about 50 Hz.

Rice. 10.5. High power voltage converter circuit

Rice. 10.6. Voltage converter circuit for powering an electric razor

Transformer T1 can be made on the basis of any network transformer with a power of 30...50 W. All pre-existing secondary windings from the transformer are removed (the network will serve as a new secondary winding), and instead of them, two half-windings are wound with PEL or PEV-2 wire with a diameter of 1.25 mm, each with a number of turns corresponding to a transformation ratio of about 20 in relation to the left winding at 220 V. If the number of turns of the high-voltage winding is unknown, the number of turns of the low-voltage winding is determined experimentally by selecting the number of turns until a voltage of 220 V is obtained at the output of the converter.

The capacitance of capacitor C5 is selected from the condition of obtaining the maximum output voltage with a connected load.

The converter circuit (Fig. 10.6) was simplified by V. Karavkin. The improvements affected only the master oscillator, the circuit of which is shown in Fig. 10.7. This generator operates at a frequency of 50 Hz.

A 12 B DC to 220 V AC converter (Fig. 10.8), when connected to a 44 Ah car battery, can power a 100-watt load for 2...3 hours. The master oscillator on a symmetrical multivibrator (VT1 and VT2) is loaded onto powerful paraphase switches (VT3 - VT8), which switch the current in the primary winding

Rice. 10.7. Variant of the master oscillator circuit for a voltage converter

Rice. 10.8. 100 W voltage converter circuit

step-up transformer T1. Powerful transistors VT5 and VT8 are protected from overvoltages when operating without load by diodes VD3 and VD4.

The transformer is made on a magnetic core ШЗбхЗб, low-voltage windings Г and I" each have 28 turns of PEL wire with a diameter of 2.1 mm, and step-up winding II has 600 turns of PEL with a diameter of 0.6 mm, and W2 is wound first, and on top of it with a double wire (with in order to achieve symmetry of the half-windings) W1. When adjusted using resistor R5, minimal distortion of the output voltage shape is achieved.

The 300 W voltage converter circuit is shown in Fig. 10.9. The master oscillator of the converter is assembled on a unijunction transistor VT1, resistors R1 - R3 and capacitor C2. The frequency of the pulses generated by it, equal to 100 Hz, is divided by the D-trigger on the DDI K561TM2 chip by 2. At the same time, paraphase pulses are formed at the outputs of the trigger, following with a frequency of 50 Hz. They, through buffer elements - inverters /SMO/7-chips K561LN2, control key transistors (block 1), connected according to a push-pull power amplifier circuit. The load of this cascade is transformer T1, which increases the pulse voltage to 220 V.

Rice. 10.9. 300 W voltage converter circuit

Transformer T1 is made on a magnetic core PL25x100x20. Windings I and II each contain 11 turns of aluminum busbar with a cross-section of 3×2 mm, winding III is made of PBD wire with a diameter of 1.2 mm and has 704 turns.

When starting to set up the device, the positive conductor of the power source is disconnected from the connection point of windings I and II of transformer T1 and, using an oscilloscope, they check the frequency and amplitude of the pulses at the bases of the transistors. The pulse amplitude should be about 2 S, and their repetition frequency, equal to 50 Hz, is set by resistor R1.

Each of the output transistors is installed on a heat sink with an area of ​​about 200 cm^. The resistors in the collector circuits of the transistors are made of nichrome wire with a diameter of 1.2 mm (10 turns on a mandrel with a diameter of 4 mm). If they are included in the emitter circuits of transistors, then the transistors of each arm can be installed on a common heat sink.

The load can be connected to the converter only after power is supplied to the circuit.

All boost converters discussed previously had an unregulated and unstabilized output voltage.

In Fig. Figure 10.10 shows a simple boost converter, the advantages of which include:

Stabilized output voltage;

Possibility of adjusting the output voltage within significant limits;

Application of widely used elements;

Using a standard TN-46-127/220-50 transformer as T1 without any modifications.

Rice. 10.10. 9...12.6V/220V, 18W boost converter circuit with adjustable stabilized AC output voltage

The converter is made using transistors VT4 and VT5 according to the classic Royer circuit. It is powered by an adjustable voltage stabilizer using transistors VT1 - VT3. It should be borne in mind that transistors VT3 - VT5 must be installed on heat sink plates. The composite zener diode VD1 - VD2 (KS147A and KS133A) can be replaced with KS182. Maximum load current - up to 100 mA.

In this article I want to talk about winding a transformer for a powerful 12-220 automotive inverter.
This transformer was wound to work in conjunction with a Chinese automotive voltage converter board.

Such inverters have recently found wide popularity due to their light weight, compact size and low price, an indispensable thing if you need to connect network loads in your car that require a 220 Volt power source, and even alternating current with a frequency of 50 Hz, the inverter is completely can provide such conditions. A few words about the converter itself; its approximate diagram is shown below.

The diagram is shown only to show the principle of operation, but this thing works in a fairly simple way.

Two generators, both TL494, the first of them operates at a frequency of about 60 kHz and is designed to drive the power transistors of the primary circuit, which in turn drive the power pulse transformer. The second generator is tuned to a frequency of about 100 Hz and controls high-voltage power transistors.

The rectified voltage after the secondary winding of the transformer is supplied to high-voltage field switches, which, when triggered at a given frequency, convert direct current into alternating current - with a frequency of 50 Hz. The output signal shape is rectangular or, more correctly, a modified sinusoid.

Our transformer is the main power component of the inverter and its winding is the most crucial moment.

The primary winding is in the form of a busbar (unfortunately I cannot indicate the exact length), the width of this busbar is about 24mm, the thickness is 0.5mm.

Operating frequency and type of master oscillator.
Inverter input voltage
Overall dimensions and type (brand) of the transformer core

First, the primary winding was wound. The two arms were wound with one solid tape, the number of turns was 2x2 turns. After winding the first two turns, a tap was made, then the remaining two turns were wound.

It is imperative to put insulation on top of the primary winding, in my case ordinary electrical tape. Number of insulation layers – 5.

The secondary winding is wound in the same direction as the primary, for example, clockwise.

To obtain 220 Volts of output voltage, in my case the winding contains 42 turns, and the winding was done in layers - the first layer is 14 turns, on top of it are two more layers that contain exactly the same number of turns.
The winding was wound with two parallel strands of 0.8 mm wire, an example of the calculation is shown below.

After all this, we assemble the transformer - we fasten the halves of the core using any electrical tape or tape, I do not recommend glue, since it can penetrate between the halves of the ferrite and form an artificial gap, which will lead to an increase in the quiescent current of the circuit and to the burning of the input transistors of the inverter, so that you need to pay great attention to this factor.

During operation, the transformer behaves very calmly, the current consumption without load is around 300 mA, but this takes into account the consumption of the high-voltage part.

The maximum overall power of the core that I used is around 1000 watts, of course the winding data will be different depending on the type of core used. By the way, winding can be done both on W-shaped cores and on ferrite rings.

Only all transformers, both industrial and home-made pulse voltage converters, are wound on this basis; by the way, the designs of home-made inverters are very often repeated by radio amateurs in projects of subwoofer amplifiers and not only, so that I think the article was interesting for many.