An inverter is a fairly complex welding tool that has recently gained enormous popularity. Excellent performance characteristics are due to a large number of technical components, the total mass of which is one device. To achieve high quality of the resulting seam, reliable operation and good technical characteristics World manufacturers are trying to introduce new developments and make powerful, but at the same time economical equipment. But it turns out that you can make the simplest welding inverter with your own hands.

Naturally, one should not expect high modern characteristics from such devices. But it is quite possible to create everything yourself, since all the components for this are freely available and if you have a complete set and a suitable diagram, you can create an inexpensive compact model. Here you need to make the right selection based on power calculations and other parameters. In other words, all parts must be compatible with each other, both in type and parameters. For example, the most vulnerable part of the device are transistors, therefore, their selection should be approached with special attention.

Advantages

• A simple DIY welding inverter is much cheaper than ready-made models of welding machines;
• When assembling it yourself, it is much easier to repair the equipment if any problems happen to it;
• You can independently adjust the configuration based on preferences, technical requirements and budget.

Flaws

• A simple homemade welding inverter turns out to be not so reliable in operation, even in comparison with budget types of equipment;
• It will take a significant amount of time to create the device, which is not always economically beneficial;
• There are no additional functions that will help improve the quality of the seam created;
• The technique has a narrow adjustment range welding current and other parameters;
• As a rule, they have problems with the cooling system;
• The housing is not created as safely as in factory models, so the use of such devices can be life-threatening.

Design and circuit of a simple inverter

A diagram of a simple welding inverter helps to determine what exactly should be included in the device. Naturally, this is not the only option and substitutions are possible. Some prefer to create more complex options, based on the diagrams of ready-made factory models, such as or, making their own changes. Here is the simplest diagram for independent implementation.

Calculation method

Before you start making the simplest welding inverter, you need to calculate its power. This is done by multiplying the current the device must have by the voltage at which the arc will burn. For example, for a current of 160 A, which will be possible at an arc voltage of 24 V, the power should be 3840 W.

Even a simple welding inverter with one transistor can have an efficiency of 85%. Thus, the power pumped by transistors should be 4517 W

Based on this value, it is possible to determine the current strength switched by the transistors during operation. To do this, you need to find the power divided by the voltage in the network. 4517/220 = 20 A.

In order to maintain a voltage of 220 V at 20 A, a filter with a capacity of 100 μF must be present in the circuit. If a large current passes through the transistors, it begins to heat them. As a rule, the rate of heat removal using radiators is insufficient, and overheating will lead to destruction of equipment. To avoid such troubles, transistors should be selected with a margin so that their operating current at 1000 degrees Celsius is at least 20 A.

Easy to repeat and make welding machine should have a voltage across the transistors no greater than the voltage in the power source. A very important parameter is the frequency of the transistors. For the parameters presented above, products with a frequency of 100 kHz are suitable. The voltage on them should be 500 V. These can be either ordinary field-effect or IGBT transistors. The only problem with their installation is the lack of special fasteners.

In order for the transistor to work normally, there must be a pause between its opening and closing. The pause time should be about 1.2 ms. The only exception can be considered Mosfet transistors, a pause in which is allowed at 0.5 ms.

Required tools and materials

In order to create a simple welding inverter using a single transistor, you should have the following set of tools:

• Screwdriver Set;
• Voltmeter;
• Multimeter;
• Soldering iron;
• Oscilloscope.

These are the main tools with which assembly, control and measurement take place. In addition, you should also have the materials that will be needed to create the device itself. For this you will need:

• Resistors with different resistance levels;
• Inductor;
• Capacitors;
• Optocoupler;
• Zener diode;
• Rectifier diodes;
• Schottke diodes;
• Transformer with two windings;
• Relay;
• Trimmer resistors;
• Diode bridge;
• Protective diode;
• Linear regulator;
• Cooling fan;
• AC to DC converter.

You should apply current to the circuit to check how the resistor closure relay operates. Next comes checking the PWM board to see if it contains rectangular pulses that may appear after the relay operates. If there are pulses, then their width in relation to the zero pause should be 44%.

You need to make sure that the voltage on the transistors does not exceed the permissible limit, otherwise all this can lead to breakdown. Power is then applied to the diode bridge to verify its correct manufacture and functionality.

During setup, you need to make sure that the transformer is wound correctly, as well as that it is connected correctly and can be controlled. This is one of the main elements that determines the adjustment of parameters, but at the same time the most difficult to implement due to the presence of a winding.

Safety precautions

All procedures must be carried out only with the power supply turned off. It is advisable to measure each part in advance so that during switching on it does not break due to overvoltage. During operation, basic electrical safety rules should be observed.

Many households would benefit from a device for electric welding of parts made of ferrous metals. Since commercially produced welding machines are quite expensive, many radio amateurs try to make a welding inverter with their own hands.

We already had an article about that, but this time I’m offering an even simpler version of a homemade welding inverter using available parts with your own hands.

Of the two main design options for the apparatus - with a welding transformer or based on a converter - the second was chosen.

Really, welding transformer- this is a large cross-section and heavy magnetic circuit and a lot of copper wire for windings, which is inaccessible to many. Electronic components for the converter with their making the right choice not in short supply and relatively cheap.

How I made a welding machine with my own hands

From the very beginning of my work, I set myself the task of creating the simplest and cheapest possible welding machine using widely used parts and assemblies.

As a result of quite lengthy experiments with various types converter using transistors and thyristors, the circuit shown in Fig. 1.

Simple transistor converters turned out to be extremely capricious and unreliable, while thyristor converters can withstand output shorting without damage until the fuse trips. In addition, SCRs heat up significantly less than transistors.

As you can easily see, the circuit design is not original - it is an ordinary single-cycle converter, its advantage is its simplicity of design and the absence of scarce components; the device uses many radio components from old TVs.

And finally, it requires virtually no setup.

The diagram of the inverter welding machine is presented below:

The type of welding current is constant, regulation is smooth. In my opinion, this is the simplest welding inverter that you can assemble with your own hands.

When butt welding steel sheets 3 mm thick with an electrode 3 mm in diameter, the steady-state current consumed by the device from the mains does not exceed 10 A. The welding voltage is turned on with a button located on the electrode holder, which allows, on the one hand, to use an increased arc ignition voltage and increase electrical safety, on the other hand, since when the electrode holder is released, the voltage on the electrode is automatically turned off. Overvoltage facilitates arc ignition and ensures stability of its combustion.

A little trick: a self-assembled welding inverter circuit allows you to connect things made of thin sheet metal. To do this, you need to change the polarity of the welding current.

The mains voltage rectifies the diode bridge VD1-VD4. The rectified current, flowing through lamp HL1, begins to charge capacitor C5. The lamp serves as a charging current limiter and an indicator of this process.

Welding should only begin after lamp HL1 goes out. At the same time, battery capacitors C6-C17 are charged through inductor L1. The glow of the HL2 LED indicates that the device is connected to the network. SCR VS1 is still closed.

When you press the SB1 button, it starts pulse generator at a frequency of 25 kHz, assembled on a unijunction transistor VT1. The generator pulses open the thyristor VS2, which, in turn, opens the thyristors VS3-VS7 connected in parallel. Capacitors C6-C17 are discharged through inductor L2 and the primary winding of transformer T1. The inductor circuit L2 - the primary winding of the transformer T1 - capacitors C6-C17 is an oscillatory circuit.

When the direction of the current in the circuit changes to the opposite, current begins to flow through the diodes VD8, VD9, and the thyristors VS3-VS7 close until the next generator pulse on the transistor VT1.

The pulses arising on winding III of transformer T1 open the thyristor VS1. which directly connects the mains rectifier based on diodes VD1 - VD4 with a thyristor converter.

LED HL3 serves to indicate the generation process impulse voltage. Diodes VD11-VD34 rectify welding voltage, and capacitors C19 - C24 smooth it out, thereby facilitating the ignition of the welding arc.

Switch SA1 is a batch or other switch with a current of at least 16 A. Section SA1.3 closes capacitor C5 to resistor R6 when turned off and quickly discharges this capacitor, which allows you to inspect and repair the device without fear of electric shock.

Fan VN-2 (with electric motor M1 according to the diagram) provides forced cooling of the device components. Less powerful fans It is not recommended to use them, or you will have to install several of them. Capacitor C1 - any one designed to operate at AC voltage 220 V.

Rectifier diodes VD1-VD4 must be designed for a current of at least 16 A and a reverse voltage of at least 400 V. They must be installed on plate corner heat sinks with dimensions of 60x15 mm, 2 mm thick, made of aluminum alloy.

Instead of a single capacitor C5, you can use a battery of several connected in parallel with a voltage of at least 400 V each, and the battery capacity may be greater than that indicated in the diagram.

Choke L1 is made on a steel magnetic core PL 12.5x25-50. Any other magnetic circuit of the same or larger cross-section is also suitable, provided that the condition of placing the winding in its window is met. The winding consists of 175 turns of PEV-2 1.32 wire (wire of a smaller diameter cannot be used!). The magnetic core must have a non-magnetic gap of 0.3...0.5 mm. Choke inductance - 40±10 µH.

Capacitors C6-C24 must have a small dielectric loss tangent, and C6-C17 must also have an operating voltage of at least 1000 V. The best capacitors I have tested are K78-2, used in televisions. You can also use more widely used capacitors of this type with a different capacitance, bringing the total capacitance to that indicated in the circuit, as well as imported film capacitors.

Attempts to use paper or other capacitors designed to operate in low-frequency circuits usually lead to their failure after some time.

It is advisable to use thyristors KU221 (VS2-VS7) with the letter index A or, in extreme cases, B or D. As practice has shown, during operation of the device the cathode terminals of the thyristors noticeably heat up, which is why it is possible that the solder joints on the board may be destroyed and even fail SCR.

Reliability will be higher if either tube-pistons made of tinned copper foil with a thickness of 0.1...0.15 mm, or bandages in the form of a tightly rolled spiral of tinned copper wire with a diameter of 0.2 mm are put on the terminal of the SCR cathode and soldered along the entire length. The piston (bandage) should cover the entire length of the terminal almost to the base. You need to solder quickly so as not to overheat the thyristor.

You will probably have a question: is it possible to install one powerful one instead of several relatively low-power SCRs? Yes, this is possible when using a device that is superior (or at least comparable) in its frequency characteristics to the KU221A thyristors. But among those available, for example, from the PM or TL series, there are none.

The transition to low-frequency devices will force the operating frequency to be lowered from 25 to 4...6 kHz, and this will lead to a deterioration in many of the most important characteristics of the device and a loud, piercing squeak when welding.

When installing diodes and SCRs, the use of heat-conducting paste is mandatory.

In addition, it has been established that one powerful thyristor is less reliable than several connected in parallel, since it is easier for them to provide Better conditions heat removal. It is enough to install a group of SCRs on one heat sink plate with a thickness of at least 3 mm.

Since current equalizing resistors R14-R18 (C5-16 V) can become very hot during welding, before installation they must be freed from the plastic shell by firing or heating with a current, the value of which must be selected experimentally.

Diodes VD8 and VD9 are installed on a common heat sink with thyristors, and diode VD9 is isolated from the heat sink with a mica spacer. Instead of KD213A, KD213B and KD213V are suitable, as well as KD2999B, KD2997A, KD2997B.

Choke L2 is a frameless spiral of 11 turns of wire with a cross-section of at least 4 mm2 in heat-resistant insulation, wound on a mandrel with a diameter of 12...14 mm.

The choke gets very hot during welding, so when winding the spiral, a gap of 1...1.5 mm should be provided between the turns, and the choke should be positioned so that it is in the air flow from the fan. Rice. 2 Transformer magnetic core

T1 is made up of three PK30x16 magnetic cores folded together from 3000NMS-1 ferrite (the horizontal transformers of old TVs were made on them).

The primary and secondary windings are divided into two sections each (see Fig. 2), wound with PSD1.68x10.4 wire in glass fabric insulation and connected in series according to. The primary winding contains 2x4 turns, the secondary winding contains 2x2 turns.

The sections are wound on a specially made wooden mandrel. The sections are protected from unwinding of turns by two tinned bandages. copper wire with a diameter of 0.8...1 mm. Bandage width - 10...11 mm. A strip of electrical cardboard is placed under each bandage or several turns of fiberglass tape are wound.

After winding, the bandages are soldered.

One of the bands of each section serves as the output of its beginning. To do this, the insulation under the bandage is made so that on the inside it is in direct contact with the beginning of the section winding. After winding, the bandage is soldered to the beginning of the section, for which purpose the insulation is removed from this section of the coil in advance and it is tinned.

It should be borne in mind that winding I operates in the most severe thermal conditions. For this reason, when winding its sections and during assembly, air gaps should be provided between the outer parts of the turns, placing short fiberglass inserts lubricated with heat-resistant glue between the turns.

In general, in the manufacture of transformers for inverter welding With your own hands, always leave air gaps in the winding. The more of them, the more effective the heat removal from the transformer and the lower the likelihood of burning the device.

It is also appropriate to note here that winding sections made with the mentioned inserts and gaskets with wire of the same cross-section 1.68x10.4 mm 2 without insulation will be cooled better under the same conditions.

The contacting bands are connected by soldering, and it is advisable to solder a copper pad in the form of a short piece of wire from which the section is made to the front ones, which serve as the leads of the sections.

The result is a rigid, one-piece primary winding of the transformer.

The secondary one is made in the same way. The only difference is the number of turns in the sections and the fact that it is necessary to provide an outlet from the middle point. The windings are installed on the magnetic circuit in a strictly defined manner - this is necessary for the correct operation of the VD11 - VD32 rectifier.

The winding direction of the upper section of winding I (when looking at the transformer from above) should be counterclockwise, starting from the upper terminal, which must be connected to inductor L2.

The winding direction of the upper section of winding II, on the contrary, is clockwise, starting from the upper terminal, it is connected to the diode block VD21-VD32.

Winding III is a turn of any wire with a diameter of 0.35...0.5 mm in heat-resistant insulation that can withstand a voltage of at least 500 V. It can be placed last, anywhere in the magnetic circuit on the side of the primary winding.

To ensure the electrical safety of the welding machine and effective cooling of all transformer elements by air flow, it is very important to maintain the necessary gaps between the windings and the magnetic core. When assembling a welding inverter with their own hands, most DIYers make the same mistake: they underestimate the importance of cooling the trance. This cannot be done.

This task is performed by four fixing plates, which are placed in the windings during the final assembly of the unit. The plates are made of fiberglass laminate with a thickness of 1.5 mm in accordance with the drawing in the figure.

After final adjustment, it is advisable to secure the plates with heat-resistant glue. The transformer is attached to the base of the device with three brackets bent from brass or copper wire with a diameter of 3 mm. The same brackets fix the relative position of all elements of the magnetic circuit.

Before installing the transformer on the base, between the halves of each of the three sets of magnetic circuits, it is necessary to insert non-magnetic gaskets made of electrical cardboard, getinax or textolite with a thickness of 0.2...0.3 mm.

To manufacture a transformer, you can use magnetic cores of other standard sizes with a cross-section of at least 5.6 cm 2. For example, W20x28 or two sets of W 16x20 made of 2000NM1 ferrite are suitable.

Winding I for the armored magnetic circuit is made in the form of a single section of eight turns, winding II is similar to that described above, from two sections of two turns. The welding rectifier on diodes VD11-VD34 is structurally a separate unit, made in the form of a shelf:

It is assembled in such a way that each pair of diodes is placed between two heat sink plates measuring 44x42 mm and 1 mm thick, made of sheet aluminum alloy.

The entire package is tightened with four steel threaded rods with a diameter of 3 mm between two flanges 2 mm thick (of the same material as the plates), to which two boards forming the rectifier terminals are attached with screws on both sides.

All diodes in the block are oriented in the same way - with the cathode terminals to the right in the figure - and the terminals are soldered into the holes of the board, which serves as the common positive terminal of the rectifier and the device as a whole. The anode leads of the diodes are soldered into the holes of the second board. Two groups of terminals are formed on it, connected to the extreme terminals of winding II of the transformer according to the diagram.

Given the large total current flowing through the rectifier, each of its three terminals is made of several pieces of wire 50 mm long, each soldered into its own hole and connected by soldering at the opposite end. A group of ten diodes is connected by five segments, of fourteen - by six, the second board with a common point of all diodes - by six.

It is better to use a flexible wire with a cross-section of at least 4 mm.

In the same way, high-current group leads from the main printed circuit board of the device are made.

The rectifier boards are made of foil fiberglass laminate 0.5 mm thick and tin-plated. Four narrow slots in each board help reduce the load on the diode leads during thermal deformation. For the same purpose, the leads of the diodes must be molded, as shown in the figure above.

In the welding rectifier you can also use more powerful diodes KD2999B, 2D2999B, KD2997A, KD2997B, 2D2997A, 2D2997B. Their number may be smaller. Thus, in one of the variants of the device, a rectifier consisting of nine 2D2997A diodes worked successfully (five in one arm, four in the other).

The area of ​​the heat sink plates remained the same, but it was possible to increase their thickness to 2 mm. The diodes were not placed in pairs, but one in each compartment.

All resistors (except R1 and R6), capacitors C2-C4, C6-C18, transistor VT1, thyristors VS2 - VS7, zener diodes VD5-VD7, diodes VD8-VD10 are mounted on the main printed circuit board, and SCRs and diodes VD8, VD9 are installed on a heat sink screwed to a board made of foil PCB 1.5 mm thick:
Rice. 5. Board drawing

The scale of the board drawing is 1:2, however, the board is easy to mark, even without using photo enlargements, since the centers of almost all holes and the boundaries of almost all foil pads are located on a grid with a pitch of 2.5 mm.

The board does not require great precision in marking and drilling holes, but remember that the holes in it must coincide with the corresponding holes in the heat sink plate.

The jumper in the circuit of diodes VD8, VD9 is made of copper wire with a diameter of 0.8...1 mm. It is better to solder it from the print side. The second jumper made of PEV-2 0.3 wire can also be placed on the parts side.

Group output of the board, indicated in Fig. 5 letters B, connected to inductor L2. Conductors from the anodes of the thyristors are soldered into the holes of group B. Terminals G are connected to the bottom terminal of transformer T1 according to the diagram, and Terminal D is connected to inductor L1.

The wire pieces in each group must be the same length and the same cross-section (at least 2.5 mm2).
Rice. 6 Heatsink

The heat sink is a 3 mm thick plate with a bent edge (see Fig. 6).

The best material for a heat sink is copper (or brass). As a last resort, in the absence of copper, you can use an aluminum alloy plate.

The surface on the installation side of the parts must be smooth, without nicks or dents. The plate has threaded holes drilled for assembly with printed circuit board and fastening elements. Part leads and connecting wires are passed through unthreaded holes. The anode terminals of the thyristors are passed through the holes in the bent edge. Three M4 holes in the heat sink are intended for its electrical connection to the printed circuit board. For this, three brass screws with brass nuts were used.Fig. 8. Placement of nodes

The unijunction transistor VT1 usually does not cause problems, but some instances, in the presence of generation, do not provide the pulse amplitude necessary for the stable opening of the SCR VS2.

All components and parts of the welding machine are installed on a base plate made of getinax 4 mm thick (textolite 4...5 mm thick is also suitable) on one side. There is a round window cut in the center of the base for mounting a fan; it is installed on the same side.

Diodes VD1-VD4, thyristor VS1 and lamp HL1 are mounted on angle brackets. When installing transformer T1 between adjacent magnetic cores, an air gap of 2 mm should be provided. Each of the clamps for connecting welding cables is an M10 copper bolt with copper nuts and washers.

The head of the bolt presses a copper square to the base from the inside, which is additionally secured against turning with an M4 screw and nut. The thickness of the angle shelf is 3 mm. An internal connecting wire is connected to the second shelf by bolting or soldering.

The printed circuit board-heatsink assembly is mounted in parts to the base on six steel posts bent from a strip 12 mm wide and 2 mm thick.

On the front side of the base there is a toggle switch handle SA1, a fuse holder cover, LEDs HL2, HL3, a handle variable resistor R1, clamps for welding cables and cable to button SB1.

In addition, four 12 mm diameter bushing posts with M5 internal threads, machined from PCB, are attached to the front side. A false panel with holes for the device controls and a protective fan grille is attached to the racks.

The false panel can be made from sheet metal or dielectric with a thickness of 1... 1.5 mm. I cut it out of fiberglass. On the outside, six posts with a diameter of 10 mm are screwed to the false panel, onto which the network and welding cables are wound upon completion of welding.

Holes with a diameter of 10 mm are drilled in the free areas of the false panel to facilitate the circulation of cooling air. Rice. 9. Appearance inverter welding machine with laid cables.

The assembled base is placed in a casing with a lid made of sheet textolite (getinax, fiberglass, vinyl plastic can be used) 3...4 mm thick. Cooling air outlets are located on the side walls.

The shape of the holes does not matter, but for safety it is better if they are narrow and long.

The total area of ​​the outlet openings should not be less than the area of ​​the input opening. The casing is equipped with a handle and a shoulder strap for carrying.

The electrode holder can be of any design, as long as it provides ease of operation and easy replacement of the electrode.

On the handle of the electrode holder, you need to mount the button (SB1 according to the diagram) in such a place that the welder can easily hold it pressed even with a mitten hand. Since the button is under mains voltage, it is necessary to ensure reliable insulation of both the button itself and the cable connected to it.

P.S. The description of the assembly process took a lot of space, but in reality everything is much simpler than it seems. Anyone who has ever held a soldering iron and a multimeter in their hands will be able to assemble this welding inverter with their own hands without any problems.

Making a welding inverter at home is a very exciting activity, especially for DIY enthusiasts. At the same time, you don’t have to have the deepest electrical knowledge, you just have to do everything strictly in a certain order. In addition, it will not be superfluous to understand the principle of operation of such a device.

The main point is to assemble everything yourself - this will save a decent amount of money if the main indicators of the device are approximately the same as those offered by the retail chain.

And the appearance of a homemade welding inverter may not differ from the factory one. The work can be carried out using electrodes 3-5 millimeters in diameter with an arc of up to 10 millimeters.

Basic data

A welding inverter assembled with your own hands according to a simple scheme can have the data of a quite decent device:

• input voltage 220 volts;
• input current is 32 amperes;
• output current is 250 amperes.

Usually a voltage of 220 volts is used, but the device can also be made for a voltage of 380 volts. Three-phase devices have slightly higher performance.

Power supply assembly

Installation begins with winding the transformer; its function is to provide stable voltage to the parts following it. For its manufacture, ferrite W 7x7 (W 8x8 is possible), on which windings of different numbers of turns are wound: one hundred, fifteen, fifteen and twenty, respectively 0.3; 1; 0.2 and 0.3 millimeters.

To reduce the harmful effects of possible differences mains voltage, the wire rings must be laid across the entire width of the coil.

The primary winding must be insulated with fiberglass and a screen made of 0.3 mm wire must be wound. It should cover the entire width of the frame, and the direction of the turns should coincide with the previous winding.

The sequence of work with the remaining windings is the same. The output should be between 20 and 25 volts. It can be adjusted by selecting parts. The sinusoidal current is converted into direct current using diodes connected like an “oblique bridge”, and for cooling it is necessary to select radiators, possibly from an old computer.

One cooler is attached to upper parts parts and is insulated with a mica gasket. The second is to the bottom of the bridge and is attached using thermal paste.

The outputs of the diode bridge are directed to the same place where the contacts of the transistors, which work as converters, will go out. The length of the wires that connect the bridge and transistors is no more than 15 centimeters. The power supply and inverter unit are separated metal plate welded to the base.

Installation of the power unit

This block is a transformer, which reduces U and increases current. To make it you need a pair of cores Ш 20х208. To isolate them from each other, it is fashionable to use paper.

Winding is performed with a strip of copper, the width of which is 40 millimeters and the thickness is 0.25 millimeters. You can use paper to lay the turns good quality, and the secondary winding is formed by placing a fluoroplastic strip.

There is no need to mount a step-down transformer using a thick wire because the current, having a high frequency, passes along the surface of the conductor and it does not heat up inside.

The heating of the device parts must be reduced by forced cooling. A fan from the computer system unit is suitable for this purpose.

Assembling the inverter unit

To make a welding inverter with your own hands, you need to move on to the next stage - installing the inverter unit. Since this node converts current from direct to alternating, you need powerful transistors, which will open and close, creating a high frequency.

In the manufacturing instructions simple inverter you can turn on the inverter block circuit.

It makes sense to mount this unit using several transistors so that the frequency is more stable and the machine hums less when welding.

Frame

Step-by-step assembly of an inverter with your own hands involves selecting a reliable housing for such a product. An old computer system unit is quite suitable for this purpose (the older the better, because the metal in it is thicker). You can make a box yourself from sheet metal, and use a half-centimeter or more getinax at the bottom.

Various types of homemade welding inverters have a common feature - this is the control of the operation of the device. A switch, a welding current adjustment knob, wiring contacts, and indicator lamps are installed on the front panel.

Thus, in order to acquire a device that is so necessary for a home workshop, it is not necessary to buy a ready-made inverter. You can study the necessary theory, purchase parts and assemble welding yourself that will work reliably.

Photo of a DIY welding inverter

To connect household devices to the car’s on-board electrical system, you need an inverter that can increase the voltage from 12 V to 220 V. There are sufficient quantities of them on store shelves, but their price is not encouraging. For those who are a little familiar with electrical engineering, it is possible to assemble a 12-220 volt voltage converter with your own hands. Two simple circuits we'll figure it out.

Converters and their types

There are three types of 12-220 V converters. The first is from 12 V to 220 V. Such inverters are popular among motorists: through them you can connect standard devices - TVs, vacuum cleaners, etc. Reverse conversion - from 220 V to 12 - is required infrequently, usually in rooms with severe operating conditions (high humidity) to ensure electrical safety. For example, in steam rooms, swimming pools or baths. In order not to take risks, the standard voltage of 220 V is reduced to 12, using appropriate equipment.

The third option is, rather, a stabilizer based on two converters. First, the standard 220 V is converted to 12 V, then back to 220 V. This double conversion allows you to have an ideal sine wave at the output. Such devices are necessary for the normal operation of most household appliances with electronic control. In any case, during installation it is strongly recommended to power it through just such a converter - its electronics are very sensitive to the quality of power, and replacing the control board costs about half the boiler.

Pulse converter 12-220V 300 W

This circuit is simple, the parts are available, most of them can be removed from a computer power supply or purchased at any radio store. The advantage of the circuit is its ease of implementation, the disadvantage is the non-ideal sine wave at the output and the frequency is higher than the standard 50 Hz. That is, devices that require power supply cannot be connected to this converter. You can directly connect not particularly sensitive devices to the output - incandescent lamps, iron, soldering iron, phone charger, etc.

The presented circuit in normal mode produces 1.5 A or pulls a load of 300 W, at a maximum of 2.5 A, but in this mode the transistors will noticeably heat up.

The circuit was built on the popular TLT494 PWM controller. Field-effect transistors Q1 Q2 should be placed on radiators, preferably separate ones. When installing on one radiator, place an insulating gasket under the transistors. Instead of the IRFZ244 indicated in the diagram, you can use IRFZ46 or RFZ48, which are similar in characteristics.

The frequency in this 12 V to 220 V converter is set by resistor R1 and capacitor C2. The values ​​may differ slightly from those shown in the diagram. If you have an old non-working power supply for your computer, and it contains a working output transformer, you can put it in the circuit. If the transformer is not working, remove the ferrite ring from it and wind the windings copper wire with a diameter of 0.6 mm. First, the primary winding is wound - 10 turns with the output from the middle, then, on top - 80 turns of the secondary.

As already said, such a 12-220 V voltage converter can only work with a load that is insensitive to power quality. To be able to connect more demanding devices, a rectifier is installed at the output, the output voltage of which is close to normal (diagram below).

The circuit shows high-frequency diodes of the HER307 type, but they can be replaced with the FR207 or FR107 series. It is advisable to select containers of the specified size.

Inverter on a chip

This 12-220 V voltage converter is assembled on the basis of a specialized KR1211EU1 microcircuit. This is a generator of pulses that are removed from outputs 6 and 4. The pulses are antiphase, with a short time interval between them to prevent the simultaneous opening of both keys. The microcircuit is powered by a voltage of 9.5 V, which is set parametric stabilizer on a D814V zener diode.

Also in the diagram there are two field effect transistor increased power - IRL2505 (VT1 and VT2). They have a very low open resistance of the output channel - about 0.008 Ohms, which is comparable to the resistance of a mechanical key. Permissible direct current is up to 104 A, pulsed current is up to 360 A. Such characteristics actually make it possible to obtain 220 V with a load of up to 400 W. Transistors must be installed on radiators (with a power of up to 200 W it is possible without them).

The pulse frequency depends on the parameters of resistor R1 and capacitor C1; capacitor C6 is installed at the output to suppress high-frequency surges.

It is better to take a ready-made transformer. In the circuit, it is turned on in reverse - the low-voltage secondary winding serves as the primary, and the voltage is removed from the high-voltage secondary.

Possible replacements in the element base:

• The D814V zener diode indicated in the circuit can be replaced with any one that produces 8-10 V. For example, KS 182, KS 191, KS 210.
• If there are no capacitors C4 and C5 of type K50-35 at 1000 μF, you can take four 5000 μF or 4700 μF and connect them in parallel,
• Instead of an imported capacitor C3 220m, you can supply a domestic one of any type with a capacity of 100-500 µF and a voltage of at least 10 V.
• Transformer - any with a power from 10 W to 1000 W, but its power must be at least twice the planned load.

When installing circuits for connecting a transformer, transistors and connecting to a 12 V source, it is necessary to use large cross-section wires - the current here can reach high values ​​(with a power of 400 W up to 40 A).

Inverter with pure sine wave output

The circuits of daytime converters are complex even for experienced radio amateurs, so making them yourself is not at all easy. An example of the simplest circuit is below.

In this case, it is easier to assemble such a converter from ready-made boards. How - watch the video.

The next video shows how to assemble a 220 volt converter with pure sine wave. Only input voltage not 12 V, but 24 V.

And this video just tells you how you can change the input voltage, but still get the required 220 V at the output.

Why do some people prefer industrial equipment made independently from available auxiliary materials? Perhaps the reason lies in the high cost quality equipment. After all, if it is necessary to carry out welding in small quantities, then many consider it inappropriate to purchase an expensive device for this. However, is this really so?

And can a simple do-it-yourself welding inverter, assembled by one of the folk craftsmen, compete in the quality of the work performed with industrially manufactured equipment? Most often, no, but still, many people still have the desire to get the necessary equipment practically for free. It is therefore worth considering how to minimal costs make the inverter yourself.

What is such a device?

Inverter device

Before you begin developing and designing equipment, you need to learn as much as possible about its operating principles. As for the welding inverter, assembled by yourself, it is worth noting that they differ from conventional ones not in the principles of creating an arc, but only in the type of power source.

The first such models appeared on the market in the late 1970s and were repeatedly improved during their use. Today they are equipped with electronic boards, which makes it possible to achieve high quality seams.

A simple welding inverter consists of two voltage converters capable of operating at high power characteristics, which can be assembled with your own hands. Moreover, they are controlled using an electronic microprocessor.

How does a welding inverter work?

The operating principle of this device is based on energy change direct current in variable frequency. Moreover, the process itself is controlled by a microprocessor and the output is an increase in frequency and current. It is executed twice. On the first converter, the current from the network turns into direct current, on the second it will again become alternating, with the only difference being that the voltage will be lower and the frequency will be high.

Let's watch the video, types of welding machines and the principle of their operation:

To make it more clear, it is worth considering the operation of a specific model of a powerful 160-amp welding inverter, assembled with your own hands. In the process of making a weld, he can use a four-electrode. But before you start work, you need to measure the voltage in the network. It should not be lower than 220 V, otherwise the electrode will stick. Otherwise, you will have to use a more powerful device.

After the inverter is started, the welding process occurs in the same way as with other types of equipment, with the only difference being that precise gap retention is not required to form an arc.

A set of components for a homemade unit

Home-grown craftsmen claim that it is not difficult to assemble an inverter on your own; the only condition is certain knowledge of electronics. If you have some experience in this area, then you can safely begin assembling the equipment.

Inverter power supply diagram

For this you will need:

• diagram - it can be found on the Internet;
• transformer and strip of tin measuring 40x0.3 mm;
• thermal layer (stationery paper and cash register tape);
• copper tape.

Having all the components at hand, you can start assembling.

Equipment assembly stages

The manufacturing process begins with winding a tape made of copper onto the transformer. There will be paper between its layers, but you need to choose a durable one so that it does not tear during use. Since it is assumed that the inverter, assembled by yourself, is operated at high frequencies, you should not use thick wires, as overheating may occur.

We watch the video, a welding machine for small parts, stages of work:

The second layer of winding is best made from three strips of copper, between which fluoroplastic insulation passes. Then the paper is used again, it will become darker over time, but this will not affect its properties.

As a fan on a simple DIY welding inverter, you can use a 0.15 A cooler from an old computer.

Once the transformer is ready, you can proceed to the cooling system. It is best if it is taken from the PC processor. For normal operation of the inverter, 6 fans are required. Moreover, three of them are for cooling the motor winding.

Let's watch the video, the stages of manufacturing a full-fledged welding machine on our own:

Next, in the process of making the inverter with their own hands, they move on to installing a power oblique bridge. It is performed on two radiators. Its upper edge is attached to one side, and the lower edge is connected to the other bridge. The diodes are brought out towards the transistors. It will also require the installation of 14 capacitors, which will help reduce emissions.

And if assembling a device according to a ready-made scheme takes 5-6 hours, then setting it up will take much longer.

Connecting equipment

To make sure it works homemade apparatus you will have to connect it to the mains. At this moment, if you assembled the inverter yourself correctly, loud sounds should appear, which mean that the unit is turned on. The fan is gradually supplied with electricity, which leads to quieter operation and reduces heating of the equipment.

Next, the relay is closed by the relay, which leads to a reduction in current surges when turned on. Experts do not recommend connecting a transformer without resistors, as this can lead to failure of the device.

You can check the amplitude of an inverter you assembled yourself using an amplifier and an optocoupler. And the correct operation of the inverter will be shown by the oscilloscope signal. If the pulses coming from different windings are exactly the same, then everything is fine with your device.

And at the last stage, you need to control the operation of the transformer, increasing the transmission level to 200 W. To find out the result, you need to connect an oscilloscope to the device.

Inverter setup

Once the equipment has been manufactured and tested for functionality, all that remains is its debugging. To do this, power is supplied to the PWM and the fan. If both systems work synchronously, then your device is ready for use.

However, it is worth checking whether the closing relay works, as well as the board itself. It is important to determine whether the identification of the presence of a pulse occurs after the relay is triggered. And only after this verification stage can voltage be applied to the bridge. In this case, the work progress can be left idle, but the current should be set to 100 mA.

Regardless design features inverter assembled with your own hands, you need to make sure correct installation transformer phases. An oscilloscope will help with this, directing the rays to the primary and secondary windings and making sure that the voltage at the lower emitter does not exceed 330 V.

IN homemade devices Sometimes there is noise on the transformer phases. You can make sure that your device does not have this drawback by checking the polarity. To do this, power is supplied to the unit bridge through any household device, for example, an electric kettle.

Specifics of operation of the assembled unit

List of causes of malfunctions

A homemade device does not always work as expected right away and this may be due to malfunctions. Therefore, when connecting an inverter welding machine assembled by yourself to the network, the current level should be 120 A. If it is lower, it means that there are problems and you need to double-check the operation of each of the nodes.

During normal startup, the indicator screen will display the operating current value - 120 A. It can be changed by pressing the corresponding button on the control panel. During the operation of a homemade inverter, it may be necessary to control the temperature of the welding unit.

In this case, you need to press both indicator buttons simultaneously. Since the devices are controlled electronically, a special program will give a signal when the temperature level exceeds the permissible level. In this case, the inverter usually does not turn off, but reduces the current level to 20 A.