How to make a welding machine with your own hands. How to assemble a welding machine at home? Three-phase transformer welding machine

It's no secret that a do-it-yourself welding machine for a person familiar with electrical engineering is not so difficult to make. This makes sense especially if it is intended for use in a personal household, where it is used only from time to time. In this case, a home-made welding machine, the cost of which is much lower than the factory one, is quite capable of replacing it. Parts for its design can be freely removed from various electrical household devices that have failed or, if necessary, manufactured and assembled by yourself. Schemes of such devices can be different. The decisive factor here is usually the availability of parts and materials.

Choosing the Right Welding Machine

All electric arc welding machines are divided into inverter and transformer. It should be noted right away that the question of how to make a welding machine on your own depends largely on the ability to get parts from certain household appliances. If all parts are purchased at market prices, then as a result, the cost will approach the price of a branded device, yielding to it in efficiency. That is why you need to have certain knowledge in the field of electrical engineering and know where which part is placed and where it can be removed for free or for a small price.

The number of turns on the primary winding should be about 240. At the same time, several taps are made to allow adjustment of the welding current in increments of 20 to 25 turns. The secondary winding is wound with copper wire with a cross section of 30 to 35 mm in an amount of 65 to 70 turns. To adjust the welding current on it, you also need to make taps. The insulation of the secondary winding must be especially reliable and heat resistant, so it should be given special attention. Each of the layers must be laid with additional insulation made of cotton fabric.

The transformer welding machine can use alternating or direct current for operation. The first of them is the simplest in terms of device, but more difficult to use. For direct current, it is quite easy to modify it by installing a diode bridge. Such a device is reliable, durable and unpretentious in use, but it has a significant weight and is sensitive to voltage drops in the mains. If it drops below 200 V, it becomes very difficult to start and maintain an electric arc.

Unlike a transformer inverter welding machine, due to the use of modern electronic parts, it has a relatively small weight. It can be worn on the shoulder by one person. Such a device has a current stabilization device, which greatly facilitates the work during welding. Reducing the voltage for it practically does not create interference, and it can operate from a household power outlet. However, the inverter apparatus is very sensitive to overheating and requires great care in operation, otherwise it easily fails.

Assembly of the transformer welding machine

The main part of such an apparatus is a transformer. Its main characteristic should be the ability to stably keep the operating current, and this is based on such an indicator as the external current-voltage characteristic of the power supply. In other words, the welding current should not differ significantly from the current produced by the short circuit.

To do this, the current must be limited in one of such ways as increasing the magnetic leakage of the transformer, ballast resistance or installing a choke. The transformer itself can be removed from a burnt high-frequency microwave oven. If there is no access to it, then you can make a welding transformer with your own hands.

To make the core, you need to purchase transformer iron plates. The core area should ideally be from 40 to 55 cm², with such indicators the winding will not overheat unnecessarily. Primary windings for self-made welding transformers should consist of thick heat-resistant copper wire with a cross section of at least 5 mm, and preferably more, enclosed in fiberglass or cotton insulation. Plastic or rubber insulation is not recommended for such purposes, since it is less resistant to overheating and breaks through more easily, which causes a short circuit in the primary winding.

It must be remembered that the secondary winding of the welding transformer must be wound on both sides of the core. It can be connected either in series or in anti-parallel. It must be remembered that the winding must be carried out on both sides in the same direction. After that, the transformer is placed in a metal case. Holes are cut from its end to cool the device, and an exhaust fan is installed, removed from the power supply of an outdated or broken computer. On the opposite side of the case, several dozen holes are drilled for air circulation. The cables and the electrode holder can then be connected.

How to assemble a homemade inverter welding machine?

An inverter welding machine can be completely assembled from parts from old TVs. This requires not only some general electrical knowledge, but also some knowledge of electronics. Its scheme is rather complicated. The inverter is a pulsed DC source, and for its manufacture, several ferrite cores are suitable, which are on horizontal transformers in old TVs. They are stacked in threes, and a winding of copper or aluminum wire is already wound on them.

Since the primary winding is most susceptible to overheating, small gaps must be left between the turns to facilitate the cooling process. It is worth remembering that aluminum wire must be taken with a larger cross section than copper, since its thermal conductivity is lower. To fix the inverter windings, a wire bandage made of 10 mm wide copper wire, superimposed on fiberglass insulation, is used.

Capacitors can also be removed from the TV, but just remember that it is not recommended to take paper capacitors from low-frequency circuits, since they will not be able to work for a long time under such loads. SCRs are better to take rather low-power ones and connect them in parallel than to take one powerful one, since a large thermal load falls on them and it is easier to cool them. SCRs are mounted on a metal plate with a thickness of at least 3 mm, which facilitates the removal of excess heat. Diodes for assembling a diode bridge can also be easily dialed from several old TVs. The bridge itself is also mounted on a heat sink plate.

Some parts for the inverter apparatus are not available on TVs, and they have to be made independently. First of all, it's a throttle. It is easy to make it without a frame of copper wire with a cross section of at least 4 mm, wound with 11 turns at intervals of at least 1 mm. Since the main thermal load will fall on the throttle, an additional air cooling system must be installed. In this capacity, it is quite possible to use an ordinary household fan mounted in the body of the welding machine in such a way that the air stream hits the throttle directly.

All elements of the electronic circuit are assembled on a fiberglass printed circuit board with a thickness of at least 1.5 mm. A heat sink is attached to the board itself, which facilitates cooling of the entire system. A round hole is cut out in the center of the board for installing a fan, since the device will not work for a long time without forced air cooling. The main advantage of the welding inverter is the ability to do mini-welding work by welding thin metal sheets. The welding seam itself comes out more accurate than that of a transformer apparatus. This is crucial for such a type of work as do-it-yourself car repair.

A do-it-yourself welding machine includes parts obtained for free or at a bargain price, but it does its job quite well.

According to experts, making a welding machine with your own hands is not difficult.

However, to make it, you need to have a clear idea for what, for what work it will be used.

A home-made device is completed and assembled from available components and parts. As an option for craftsmen, a plasma mechanism can also be considered.

Practice shows that with an accurate selection of components, the device will serve for a long time and reliably.

It is important that the electrical circuit is as simple as possible. Sometimes they even use a microwave transformer.

The device must be operated from a 220 V AC household mains.

If you choose 380 V as the operating voltage, then the circuit and design of the device will become noticeably more complicated.

Structural diagram of the welding machine

For the production of welding works, devices operating on alternating and direct current are used.

The circuit of any apparatus includes a transformer (it is possible to use a transformer from a microwave oven), a rectifier, a choke, a holder, an electrode. It is in this sequence that electric current flows through a closed circuit.

The circuit is completed when an electric arc occurs between the electrode and the metal pieces to be connected.

In order for the quality of the welded joint to be high, it is necessary to ensure stable burning of this arc.

And to set the required combustion mode, a current regulator is used.

DC machines are used for welding elements made of thin sheet metal. With this welding method, any electrodes and electrode wire without ceramic coating can be used.

The electrode holder is connected to the rectifier through a choke. This is done in order to smooth out voltage ripples.

The inductor is a coil of copper wires, which is wound on any core. The rectifier, in turn, is connected to the secondary winding of the transformer.

The transformer is connected to the household electrical network. The connection sequence is simple and clear.

AC voltage conversion is performed using a step-down transformer.

According to Ohm's law, the voltage that is induced on the secondary winding of the transformer decreases, and the current increases from 4 amperes to 40 or more.

Approximately this value is required for welding. In principle, this device can be called the simplest welding machine.

And with the help of wires, attach the electrode holder to it. But it is impossible to use the holder for practical purposes, since the circuit does not contain other necessary elements.

And most importantly - it does not have a current magnitude regulator. As well as a rectifier and other elements.

The transformer is considered the main element of the welding machine. It can be bought or adapted already used.

Many craftsmen use a transformer from a microwave oven that has served its time. Due to its dimensions and weight, the micropulse element always takes up a lot of space in the structure.

If we consider the welding unit as a whole, then we can distinguish three main blocks that it includes:

• power unit;
• rectifier block;
• inverter block.

A home-made inverter apparatus can be arranged in such a way that it has minimal dimensions and weight.

Such devices, designed for use in the household, are now sold in stores.

The advantages of the inverter apparatus over traditional units are obvious. First of all, it should be noted the compactness of the device, ease of use, reliability.

Only one component in the parameters of this device is of concern - its high cost.

The most general calculations confirm that making such an apparatus with your own hands is easier and more profitable.

The main elements, in practice, can always be found among electrical machines and devices that ended up in storerooms. Or in a landfill.

The simplest current regulator can be made from a piece of heating coil, which is used in household electric stoves. Choke - from a piece of copper wire.

Radio amateurs came up with the simplest pulse welding method according to the scheme. It is used to attach wires to a metal board.

No complicated fixtures - just a choke and a couple of wires. The current regulator is also not needed. Instead, a fusible link is included in the circuit.

One electrode is connected to the board through a choke.

As the second, a crocodile clip is used. The plug with wires is included in the socket of a household network.

The clamp with the wire is sharply applied to the board in the place where it needs to be welded. A welding arc occurs and at this moment the fuses in the electrical panel may blow.

This does not happen because the fusible link burns out faster. And the wire remains securely welded to the board.

Product package

Homemade is going to do small jobs in the household.

All elements, electronic devices, wires and metal structures must be assembled in a specific place. Where the product will be assembled.

The choke can be used from the fittings of a fluorescent lamp. The number of wires, preferably copper, of different sections, you need to stock up more.

If the throttle in finished form could not be found, then it must be made independently.

This will require a steel magnetic circuit from an old starter and several meters of copper wires with a cross section of 0.9 squares.

Power Supply

The main element of the power supply in the inverter is a transformer.

It can be converted from a laboratory autotransformer or used to remake a microwave oven transformer that has already served its time.

It is very important not to damage the primary winding when removing the transformer from the microwave oven.

The secondary winding is removed and redone. The number of turns and the diameter of the copper wires are calculated depending on the pre-selected power of the welding machine.

The spot welding method is well implemented by an apparatus made on a microwave transformer.

The rectifier is used to convert AC voltage to DC voltage. The main elements of this device are diodes.

It is switched into certain circuits, most often bridges. An alternating current is supplied to the input of such a circuit, and a direct current is removed from the output terminals.

Diodes are selected with such power to withstand the initially specified loads. For their cooling, special radiators made of aluminum alloys are used.

When marking the installation board, it is advisable to provide a place for a choke, which is designed to smooth out the pulses. The rectifier is assembled on a separate board, from getinax or textolite.

Inverter block

The inverter converts the direct current coming from the rectifier into alternating current, which has a high oscillation frequency.

The conversion is performed using electronic circuits on thyristors or powerful transistors.

If a voltage of 220 volts with a frequency of 50 Hz is applied to the input terminals of the transformer, then a direct current of up to 150 amperes and a voltage of 40 volts is fixed at the output terminals of the inverter.

These current parameters allow you to weld metal parts from various alloys.

The electronic regulator allows you to select the mode corresponding to a particular operation.

Practice shows that a home-made welding machine, in terms of its characteristics, is not inferior to factory products.

Some time ago, welding mini inverters appeared in the trading network. It took years for manufacturing companies to achieve this miniaturization.

While craftsmen have long been able to make a do-it-yourself plasma welding machine.

This step was prompted by local conditions - tightness in the workshop and the significant weight of factory inverters. A plasma machine is a great way out of this situation.

And the fact that instead of copper wires the secondary winding of the transformer is made of copper sheet has also long been known.

Assembly sequence of the welding machine

When placing elements on a metal or textolite basis, a certain order must be observed. The rectifier must be located near the transformer.

The inductor is on the same board as the rectifier. The current regulator must be located on the control panel. The body of the apparatus can be made of sheet steel or aluminium.

Or adapt the chassis from an old oscilloscope and even a computer system unit. It is very important not to "sculpt" the elements as close to one another as possible.

It is imperative to make holes in the walls for the installation of cooling fans and a constant flow of air.

The board with thyristors and other elements is placed as far as possible from the transformer, which gets very hot during operation. Just like a rectifier.

If you have a need to perform some simple welding work for domestic needs, it is not at all necessary to purchase an expensive factory unit. After all, if you know some of the subtleties, you can easily assemble a welding machine with your own hands, which will be discussed below.

Welding machines: classification

All welding machines are either electric or gas. It should be said right away that home-made welding machines should not be gas. Since they include explosive gas cylinders, it is not worth keeping such an installation at home.

Therefore, in the context of self-assembly of structures, we will talk about exclusively about electrical options. Such units are also divided into varieties:

1. Generator sets - equipped with their own current generator. A distinctive feature - the big weight and dimensions. For home needs, this option is not suitable, and it will be difficult to assemble it yourself.
2. Transformers - such installations, especially of the semi-automatic type, are very common among those who make welding equipment on their own. They are powered by a network of 220 or 380 V.
3. Inverters - such installations are easy to use and ideal for the home, the design is compact and lightweight, but the electronic circuit is quite complex.
4. Rectifiers - these devices are easy to assemble and use for their intended purpose. With their help, even a beginner can perform high-quality welds.

To assemble an inverter at home, you will need a circuit that will allow you to comply with the necessary parameters. It is recommended to take parts from old Soviet devices:

The options for the device are as follows:

• It must work with electrodes whose diameter does not exceed 5 mm.
• The maximum operating current is 250 A.
• Voltage source - household network for 220 V.
• Adjustment of welding current varies from 30 to 220 A.

The tool includes the following components:

• power unit;
• rectifier;
• inverter.

Begin from transformer winding and act in the following order:

1. Take the ferrite core.
2. Perform the first winding (100 turns with a 0.3 mm PEV wire).
3. The second winding is 15 turns, with a wire with a cross section of 1 mm).
4. The third winding is 15 turns with a PEV wire of 0.2 mm.
5. The fourth and fifth - respectively, 20 turns each with wires with a cross section of 0.35 mm.
6. To cool the transformer, take a fan from the computer.

In order for transistor switches to work continuously, voltage should be applied to them after the rectifier and capacitors. Assemble the rectifier unit according to the diagram on the board, and fix all the components of the device in the case. Can be used old radio housing, but you can do it yourself.

Installed from the front of the case led indicator, which indicates that the device is connected to the network. Here you can put an additional switch, as well as a protective fuse. You can also install it on the back wall and even in the case itself.

It all depends on its size and design features. Variable resistance is installed on the front of the case, with its help you can adjust the operating current. When you have collected all the electrical circuits, check the device with a special device or tester and you can test it.

The assembly of the transformer version will be somewhat different from the previous one. This unit runs on alternating current, but for DC welding, you need to assemble a simple attachment to it.

To work you will need transformer iron for the core, as well as several tens of meters of thick wire or thick copper bus. All this can be found at the metal collection point. The core is best made U-shaped, toroidal or round. Many also take the stator from an old electric motor.

The assembly instruction for the U-shaped core looks like this:

• Take transformer iron with a cross section of 30 to 55 s m 2. If the indicator is higher, the device will turn out to be too heavy. And if the cross section is less than 30, the device will not be able to work correctly.
• Take a copper winding wire with a cross section of about 5 mm 2, equipped with heat-resistant fiberglass or cotton insulation. Insulation is important because the winding can heat up to 100 degrees or more during operation. The winding wire has a square or rectangular cross section. However, such an option is difficult to find. An ordinary one with a similar cross section is also suitable, but only you will need to remove the insulation from it, wrap it with fiberglass and carefully impregnate it with electrical varnish, and then dry it. The primary winding has 200 turns.
• The secondary winding will require about 50 turns. The wire does not need to be cut. Connect the primary winding to the network, and on the secondary wires, find a place where the voltage is about 60 V. To find such a point, unwind or wind additional turns. The wire can be aluminum, but the cross section must be 1.7 times larger than for the primary winding.
• Install the finished transformer into the housing.
• To bring the secondary winding, copper terminals are required. Take a tube with a diameter of 10 mm and a length of about 4 cm. Rivet its end and drill a hole with a diameter of 10 mm, and insert the end of the wire, previously stripped of insulation, into the other end. Next, crimp it with light hammer blows. To strengthen the contact of the wire with the tube-terminal, apply notches on it with a core. Screw homemade terminals to the body with nuts and bolts. Details are best used copper. When winding the secondary winding, it is desirable to make taps every 5-10 turns, they will allow you to change the voltage on the electrode in steps;
• To make an electric holder, take a pipe with a diameter of about 20 mm and a length of about 20 cm. At the ends, about 4 cm from the end, cut notches to half the diameter. Insert the electrode into the recess and press it with a spring based on a welded steel wire bush with a diameter of 5 mm. Attach the same wire that was used for the secondary winding to the second horse with a nut and screw. Slide a rubber tube with a suitable inner diameter onto the holder.

It is best to connect the finished device to the network using wires with a cross section of 1.5 s m 2 or more, as well as a knife switch. The current in the primary winding usually does not exceed 25 A, and in the secondary it ranges from 6-120 A. When working with electrodes with a diameter of 3 mm, every 10-15 make stops to let the transformer cool down. If the electrodes are thinner, this is not necessary. More frequent breaks are needed if you are working in cutting mode.

DIY mini welding

To assemble a miniature welding machine yourself, you only need a few hours and the following materials:

Gently at first disassemble the old battery and remove the graphite rod from it. At the end, sharpen it with sandpaper and wipe it with a dry cloth. Peel off the insulation from the end of a piece of thick wire 4-5 cm from the end and bend the loop using pliers or side cutters. Insert a carbon electrode into it.

Remove the secondary winding from the transformer and replace it wrap thick wire for 12-16 turns. Now all this is inserted into a suitable case - and the device is ready.

Its wires are connected to the terminals of the secondary winding, carbon the rod is inserted into the loop and crimps well. Connect the positive terminal to the electrode holder, and the negative terminal to the twisting of the working parts. The handle holder can be adapted for the electrode.

You can use a soldering iron or something similar. Plug the appliance into the household network and carry out connecting parts with graphite. A flame should appear, and a spherical weld will form at the end of the parts.

For a home workshop, the presence of a welding machine is very important. Such devices have different designs and modifications. Both beginners and experienced craftsmen often prefer not factory-made, but home-made devices that can be modified in their own way.

It is difficult to do without a welding machine in construction, installation and repair. Usually they buy equipment in finished form. However, you can go the other way: make the welding machine yourself, because a self-made device will save a lot of money and will become an exciting thing for those who like to craft.

About connection methods, windings and electrode

There are different types of welding machines. The most common mistake novice craftsmen make is the desire to immediately make a complex device. Schemes for the production of a welding machine are easy to find on the Internet, it is best to give preference to the type of equipment, the manufacture of which will not cause significant difficulties and will not take much time. Repairing your own welding machine will not bring big problems and significant cash costs for the person who manufactured the equipment.

A logical question immediately arises: which welding machine is best suited for working at home? Only small size. The best solution to the problem would be to create an apparatus from the devices already at the disposal of the craftsman. For work, a three-phase transformer is required. Primary must be connected. At the welding machine, this is done on the “triangle” magnetic circuit. This method is used only for the device, which is planned to be connected to a three-phase network with a voltage of 380/220 V.

The power supply and the specifics of the design of the apparatus are the task, the solution of which must be paid attention in the first place. If the power supply and the internal structure of the equipment do not match, this will lead to the fact that the equipment, which took time and effort to create, will pose a danger to human life and health. If the welding machine is to be powered from a single-phase 220 V network, the connection of the primary winding of the transformer must be made differently. The extreme rods of the magnetic circuits of the apparatus are connected in an anti-parallel manner. For such a welding machine, a different principle of fastening the secondary windings is used: a fixed circuit.

If the device is powered by a single-phase 220 V network, it also differs in the features of the additional winding. It is wound on all the windings of the electric wire that the welding machine has. What is it for? During welding, stepwise changes in the welding current occur. They need a ballast, whose role is played by an additional winding. Its distinguishing feature: 40-50 turns. For a small-sized welding machine, a two-stage regulation of the electric power supply is most suitable.

Beginners often choose the wrong electrode size for the device.

In order to make a DC welding machine yourself, you need a high-power power source that is capable of converting the rated voltage of a conventional single-phase network and providing a constant value of the corresponding current. This is necessary in order to create and maintain a normal electric arc.

For a high power power supply, the following components will be required:

1. Rectifier.
2. Inverters.
3. Current and voltage transformer.
4. Current and voltage regulators (to improve the quality characteristics of the electric arc itself).
5. Auxiliary devices.

There is a simple rule that will help you make the right choice: the stronger the electrical network and the thicker the wiring, the larger the electrode should be.
The main components of the welding machine:

1. Transformer magnetic circuit.
2. primary windings.
3. secondary windings.
4. Additional winding.
5. Remote capacitors.
6. Welding mode switch.
7. Contact temperature sensor and alarm sound device.
8. Welding mode switches.

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Why is concrete needed?

The body of the welding machine is an important issue. For the manufacture of cases of such equipment, it is customary to use specially prepared concrete. It should have a good indicator of plasticity. The one that most easily takes the desired shape and freezes in the shortest possible time is suitable.

The hull will require fine-grained sand and cement. The first should be 75% of the dry mix of concrete, the second - its fifth. The remaining 5% of the dry mixture is PVA glue and glass wool in a 1: 1 ratio. Instead of glue, water-soluble latex can be used.

Many novice craftsmen believe that making a welding machine is much easier than making its body. In fact, there is nothing complicated if you perform all the actions sequentially. The main mistake is the wrong thickness of the body, it should not be less than 1 cm. The welding machine must be cleaned. Then the device is dried and only then proceed to the manufacture of the case. When the concrete has hardened, the welding machine must be processed from the outside. This requires an organic monomer.

For this task, styrene or methyl methacrylate is suitable. Once the concrete has been impregnated with the monomer, it is necessary to heat treat the surface. The temperature for these purposes must be at least 70 0 C. In this case, the polymerization of the monomer occurs. As a result of this procedure, a waterproof layer is formed on the body of the apparatus itself. After it, the welding machine will be protected from the effects of the external environment.

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The easiest way

Spot welding is most in demand in everyday life, but often a person simply does not have time to manufacture the complex interior of the welding machine. If it causes difficulties, you can resort to the most primitive solution to the issue. Check: what faulty household appliances are in the house.

If a microwave oven breaks down, do not rush to throw it away - with new electrical wiring, pieces of wood, clamps and tips - a spot welding machine can be made very quickly.

You will need:

1. Washers.
2. Self-tapping screws.
3. Staples.

They must correspond to the intended dimensions of the welding machine. If the broken microwave oven has a working transformer, it will become the basis of new home-made equipment.

In view of the fact that in everyday life ordinary people often need to work with metal, many use welding machines. But not everyone can afford the purchase of expensive equipment, which raises the question of how to assemble a welding machine with your own hands. The manufacturing process will differ depending on the type and design features of the welding device.

Types of welding machines

The modern market is filled with a fairly large variety of welding machines, but it is far from advisable to assemble everything with your own hands.

Depending on the operating parameters of the devices, the following types of devices are distinguished:

• on alternating current - giving out alternating voltage from the power transformer directly to the welding electrodes;
• at direct current - giving out a constant voltage at the output of the welding transformer;
• three-phase - connected to a three-phase network;
• inverter devices - issuing a pulsed current into the working area.

The first version of the welding unit is the simplest, for the second one you need to modify the classic transformer device with a rectifier unit and a smoothing filter. Three-phase welding machines are used in industry, so we will not consider the manufacture of such devices for domestic needs. An inverter or pulse transformer is a rather complicated device, so in order to assemble a homemade inverter, you must be able to read circuits and have basic electronic board assembly skills. Since the basis for the creation of welding equipment is a step-down transformer, we will consider the manufacturing procedure from the simplest to the more complex.

On alternating current

Classical welding machines work according to this principle: the voltage from the primary winding of 220 V is reduced to 50 - 60 V on the secondary and is fed to the welding electrode with the workpiece.

Before you start manufacturing, select all the necessary elements:

• Magnetic core- stacked cores with a sheet thickness of 0.35 - 0.5 mm are considered more profitable, since they provide the smallest losses in the gland of the welding machine. It is better to use a ready-made core made of transformer steel, since the density of the plates fit plays a fundamental role in the operation of the magnetic circuit.
• Coil winding wire- the cross section of the wires is selected depending on the magnitude of the currents flowing in them.
• Insulating materials- the main requirement, both for sheet dielectrics and for the native coating of wires, is resistance to high temperatures. Otherwise, the insulation of the semi-automatic welding machine or transformer will melt and a short circuit will occur, which will lead to a breakdown of the machine.

The most profitable option is to assemble the unit from a factory transformer, in which both the magnetic circuit and the primary winding are suitable for you. But, if there is no suitable device at hand, you will have to make it yourself. You can familiarize yourself with the principle of manufacturing, determining the cross section and other parameters of a home-made transformer in the corresponding article:.

In this example, we will consider the option of manufacturing a welding machine from a microwave power supply. It should be noted that transformer welding must have sufficient power; for our purposes, a welding machine of at least 4–5 kW is suitable. And since one microwave transformer has only 1 - 1.2 kW, we will use two transformers to create the apparatus.

To do this, you will need to perform the following sequence of actions:

Rice. 2: remove the high voltage winding

leaving only low-voltage, in this case, winding the primary coil is no longer necessary, since you are using the factory one.

• Remove the current shunts from the coil circuit on each transformer, this will increase the power of each winding.
  Rice. 3: remove current shunts
• For the secondary coil, take a copper bus with a section of 10 mm 2 and wind it on a pre-made frame from any materials at hand. The main thing is that the shape of the frame repeats the dimensions of the core.
  Rice. 4: wind the secondary winding on the frame
• Make a dielectric gasket for the primary winding, any non-combustible material will do. In length, it should be enough for both halves after connecting the magnetic circuit.
  Rice. 5: make a dielectric pad
• Place the power coil in the magnetic core. To fix both halves of the core, you can use glue or pull them together with any dielectric material.
  Rice. 6: put the coil into the magnetic core
• Connect the outputs of the primary to the power cord, and the secondary to the welding cables.
  Rice. 7: connect the power cord and cables

Install a holder and an electrode with a diameter of 4 - 5 mm on the cable. The diameter of the electrodes is selected depending on the strength of the electric current in the secondary winding of the welding machine, in our example it is 140 - 200A. With other operating parameters, the characteristics of the electrodes change accordingly.

In the secondary winding, 54 turns were obtained, in order to be able to adjust the voltage at the output of the device, make two taps from 40 and 47 turns. This will allow you to adjust the current in the secondary by reducing or increasing the number of turns. The same function can be performed by a resistor, but only to the lower side of the nominal value.

DC

Such an apparatus differs from the previous one in more stable characteristics of the electric arc, since it is obtained not directly from the secondary winding of the transformer, but from a semiconductor converter with a smoothing element.

Rice. 8: Rectification circuit diagram for welding transformer

As you can see, it is not required to wind the transformer for this, it is enough to modify the circuit of the existing device. Thanks to this, he will be able to produce a more even seam, cook stainless steel and cast iron. For manufacturing, you will need four powerful diodes or thyristors, approximately 200 A each, two capacitors with a capacity of 15,000 microfarads and a choke. The connection diagram of the smoothing device is shown in the figure below:

Rice. 9: connection diagram of the smoothing device

The process of finalizing the electrical circuit consists of the following steps:

Due to the overheating of the transformer during operation, the diodes can quickly fail, so they need forced heat dissipation.

For connection, it is better to use tinned clamps, as they will not lose their original conductivity from high currents and constant vibration.

Rice. 12: use tinned clips

The thickness of the wire is selected in accordance with the operating current of the secondary winding.

When welding metals with such an apparatus, it is always necessary to control the heating of not only the transformer, but also the rectifier. And when the critical temperature is reached, pause for the elements to cool, otherwise the do-it-yourself welding unit will quickly fail.

inverter apparatus

It is a rather complicated device for beginner radio amateurs. No less difficult process is the selection of the necessary elements. The advantage of such a welding machine is significantly smaller dimensions and lower power, in comparison with classical devices, the ability to implement, etc.

Rice. 14: circuit diagram of the pulse unit

In operation, such a circuit converts the alternating voltage from the network to a constant one, then, using a pulse unit, it outputs a high-amplitude current to the welding area. This achieves relative savings in the power of the apparatus in relation to its performance.

Structurally, the inverter circuit of the welding machine includes the following elements:

• diode rectifier with capacity magazine, ballast resistor and soft start system;
• control system based on a driver and two transistors;
• power part of the control transistor and output transformer;
• output part of diodes and inductor;
• cooler cooling system;
• current feedback system to control the parameter at the output of the welding machine.

For you, you will need to wind a power transformer yourself, a current transformer based on a ferrite ring. For the bridge, it is better to use a ready-made assembly of high-speed semiconductor elements.

Unfortunately, most of the other items are unlikely to be at hand in the garage or at home, so they will have to be ordered or purchased from specialized stores. Because of this, assembling an inverter unit with your own hands will cost no less than the factory version, but taking into account the time spent, it will also be more expensive. Therefore, for inverter welding, it is better to purchase a ready-made machine with the specified operating parameters.

Video instructions