If a person plans to perform living conditions small volumes of any simple welding work, he can easily make a welding machine with his own hands, without spending money on purchasing a factory unit.

1

In order to make a welding unit from readily available materials and parts, it is necessary to clearly understand the key principles of its operation and only then begin assembly. First of all, you should decide on the current power of your homemade welding machine. To connect massive reinforcement, of course, high current intensity is required, and for welding thin metal products(no more than 2 mm) – smaller.

The current indicator is directly related to which electrodes are planned to be used. Welding of sheets and structures with a thickness of 3 to 5 mm is carried out with 3–4 mm rods, and with a thickness of less than 2 mm – with 1.5–3 mm rods. If you use four-millimeter electrodes, the current strength homemade installation should be 150–200 A, three-millimeter – 80–140 A, two-millimeter – 50–70 A. But for very thin parts (up to 1.5 mm), a current of 40 A is quite sufficient.

The formation of an arc for welding from mains voltage in any welding machine is achieved through the use of a transformer. This device includes in its design:

• windings (primary and secondary);
• magnetic circuit

It's easy to make a transformer yourself. The magnetic core, for example, is assembled from transformer steel plates or other material. The secondary winding is necessary directly for welding work, and the primary winding is connected to a 220-volt electrical network. Professional units necessarily have in their design some additional devices that improve and enhance the quality of the arc and allow you to smoothly adjust the current intensity.

Homemade welding machines, as a rule, are made without additional devices. The power of the transformer is selected based on the current strength. To obtain the calculated power, you need to multiply the current used for welding by 25. The resulting product, when multiplied by 0.015, gives us the required diameter of the magnetic core. And to calculate the required winding cross-section (primary), the power should be divided by two thousand and multiplied by 1.13.

Determining the cross-section of the secondary winding will have to “suffer” a little longer. Its value depends on the density of the used welding current. With a current strength of around 200 A, the density is 6A/square millimeter, from 110 to 150 A - 8, less than 100 A - 10. To set the required cross-section of the secondary winding you need:

• divide the welding current by its density;
• multiply the resulting value by 1.13.

The number of turns of wiring can be determined by dividing the cross-sectional area of ​​the magnetic circuit by 50. Another important point, which those who plan to know need to know self-production welding machine, is that the welding process can be “soft” or “hard” depending on the voltage available at the output terminals (at their clamps) of the unit.

The specified voltage sets the features external characteristics current for welding, which can be gently or steeply falling, as well as increasing. In self-assembled welders, experts advise using current sources that are described by a flat or steeply falling characteristic. They show minimal changes in current when the electric arc oscillates, which is optimal for welding at home.

2

Now that we know the main features of the welder, we can begin assembling a homemade welding machine. Now on the Internet there are many diagrams and instructions for performing such a task, which make it possible to create almost any equipment for welding - AC and DC, pulsed and inverter, automatic and semi-automatic.

We will not go into complex technical “wilds”, and will tell you how to make a welding machine of the simplest transformer type. He will work for alternating current, providing an effective and quite decent quality seam welded joint. Such a unit will allow you to perform any household work, which require welding of metal and steel products. To make it you will need the following materials:

• a couple of tens of meters of thick (preferably copper) cable (wire);
• iron for core transformer device(iron must have a sufficiently high magnetic permeability).

It is most convenient to make the core a rod, in a traditional U-shape. In principle, it is also possible to use a core of a different configuration, for example, a round one from the stator of any burnt-out electric motor, but be prepared for the fact that it is much more difficult to wind windings onto a round structure. The recommended cross-sectional area of ​​the core for a standard household welding unit, made independently, is about 50 square centimeters.

This area is enough for the installation to use rods with a diameter of 3–4 millimeters.

There is no point in making a larger cross-section, since the unit will become much heavier, but you will not achieve a real technical effect. If you are not satisfied with the recommended cross-sectional area, you can calculate its value yourself using the diagram given in the first part of our article.

The primary winding must be made of high-performance copper wire thermal resistance(during welding, the winding is exposed to high temperatures). This wire, in addition, must have cotton or fiberglass insulation. As a last resort, it is allowed to use a wire in a rubber-fabric or ordinary rubber insulating sheath, but in no case in a polyvinyl chloride sheath.

By the way, you can make the insulation yourself by cutting two-centimeter wide strips of cotton or fiberglass. With these strips you wrap copper cable, after which you impregnate the wire with homemade insulation with any electrical varnish. Believe me, such insulation will not overheat when using 6–7 welding rods (when they are burned on average duration welding works).

The cross-sectional areas of the windings are calculated according to the principles that were outlined earlier. It seems that you will not have any problems with these calculations. Typically, the cross-sectional area of ​​the “secondary” wire is taken at the level of 25–30 square millimeters, the “primary” – 5–7 (values ​​for homemade units, which will work with rods with a diameter of 3–4 millimeters).

It is also easy to determine the length of a piece of copper wire and the number of turns for both windings. And then they begin to wind the coils. Their frame is made according to geometric parameters magnetic circuit. The dimensions are selected in such a way that the magnetic circuit fits onto the core, made of textolite or cardboard used in electrical engineering, without any difficulty.

The winding of the coils has a small peculiarity. The primary winding is wound in half, then half of the secondary is placed on it. After this, the second part of the coil is processed in a similar way. To improve insulating properties It is advisable to place pieces of cardboard strips, fiberglass or thick paper between the layers.

After assembling a do-it-yourself welding installation, it must be adjusted. To do this, you need to plug it into the network and measure the voltage on the secondary winding. Its value should be 60–65 V. If the voltage is different, you will need to wind (or wind) part of the winding. Such procedures will have to be performed until the specified voltage value is achieved.

The primary winding of the assembled transformer is connected to an internal laying cable (IRP) or to a two-core hose wire (SHRPS), which will be connected to a 220 volt network. The secondary winding (its leads) is connected to insulated PRG wires, one of them is then in contact with the product being welded, and the welding rod holder is attached to the second. The homemade welding unit is ready!

3

In his practice, any radio amateur often needs to strongly heat or carefully weld one or another part. There is no point in using a conventional welding unit for these purposes, since even without it you can form a high-temperature flow quite simply and without expense.

If you have an old autotransformer lying around, which was previously used to regulate the supply voltage of Soviet lamp-based TVs, it is easy to adapt it to create a voltaic arc. To do this, you need to connect graphite electrodes between its terminals. Such a simple design will make it possible to perform simple welding work, for example, the following:

• repair or production of thermocouples: a welder from an autotransformer allows you to repair thermocouples in which the so-called “ball” breaks, and other equipment for similar repair work simply does not exist;
• connecting the power buses to the filament element of a conventional magnetron;
• welding of any wires and cables;
• heating structures made of springs and similar parts to high temperatures;
• hardening of all kinds of devices made from (they are heated with an arc and then immersed in machine oil).

If you decide to make a welder based on an autotransformer, you need to handle it extremely carefully, since electrical network it has no galvanic isolation. This means that misuse homemade device may result in electric shock.

To perform all the above “minor” work, it is recommended to use an automatic transformer with a voltage (output) of 40–50 volts with low power (about 200–300 watts). Such a device is capable of delivering 10–12 amperes of operating current, which is quite enough for welding wires, thermocouples and other elements. The electrodes for the described mini-welding machine are ordinary pencil leads.

It is better if they are soft, however, medium and hard pencils are also suitable. Holders for such graphite rods can be made from old terminal blocks found on any electrical devices. The holder is connected to the winding (as you understand, secondary) of the autotransformer through one of the existing terminals, and the product that needs to be welded is also connected to it, but through a different terminal.

The handle of the electrode holder can be easily made from an ordinary fiberglass washer or from another heat-resistant element. Finally, let’s say that the arc on a welding machine from an autotransformer does not burn for very long. On the one hand, this is bad, on the other hand, it is very good, since the short duration of its operation eliminates the risk of overheating of the transformer device.

A welding machine is a fairly popular device among both professionals and home craftsmen. But for household use sometimes there is no point in buying an expensive unit, since it will be used in rare cases, for example, if you need to weld a pipe or install a fence. Therefore, it would be wiser to make a welding machine with your own hands, investing a minimal amount of money in it.

The main part of any welder working on the principle of electric arc welding is a transformer. This part can be removed from an old, unnecessary household appliances and make a homemade welding machine out of it. But in most cases, the transformer requires minor modifications. There are several ways to make a welder, which can be either the simplest or more complex, requiring knowledge in radio electronics.

To make a mini-welding machine, you will need a couple of transformers removed from an unnecessary microwave oven. It’s easy to find a microwave from friends, acquaintances, neighbors, etc. The main thing is that it has a power in the range of 650-800 W, and it has a working transformer. If the stove has a more powerful transformer, then the device will have higher current ratings.

So, the transformer removed from the microwave has 2 windings: primary (primary) and secondary (secondary).

Resale has more turns and a smaller wire cross-section. Therefore, in order for the transformer to become suitable for welding, it must be removed and replaced with a conductor with a larger cross-sectional area. To remove this winding from the transformer, it must be cut off on both sides of the part using a hacksaw.

This must be done with special care so as not to accidentally touch the primary winding with the saw.

When the coil is cut down, its remains will need to be removed from the magnetic circuit. This task will be much easier if you drill through the windings to relieve metal stress.

Do the same operations with the other transformer. As a result, you will get 2 parts with a primary winding of 220 V.

Important! Don't forget to remove the current shunts (shown by arrows in the photo below). This will increase the power of the device by 30 percent.

To make a secondary one, you will need to purchase 11-12 meters of wire. It must be multi-core and have cross section of at least 6 squares.

To make a welding machine, you will need to wind 18 turns (6 rows high and 3 layers thick) for each transformer.

You can wind both transformers with one wire or separately. In the second case, the coils should connect in series.

The winding should be done very tightly so that the wires do not dangle. Next, the primary windings need connect in parallel.

To connect the parts together, they can be screwed to a small piece of wood.

If you measure the voltage on the secondary of the transformer, then in this case it will be equal to 31-32 V.

This homemade welder can easily weld metal 2 mm thick with electrodes with a diameter of 2.5 mm.

It should be remembered that you should cook with such a homemade apparatus with rest breaks, since its windings become very hot. On average, after each electrode is used, the device should cool down for 20-30 minutes.

It will not be possible to cook thin metal with a unit made from a microwave, as it will cut it. To regulate the current, you can connect a ballast resistor or choke to the welder. The role of a resistor can be played by a segment steel wire of a certain length (selected experimentally), which is connected to the low-voltage winding.

AC welder

This is the most common type of metal welding machine. It is easy to make at home and is easy to use. But the main drawback of the device is large mass of step-down transformer, which is the basis of the unit.

For home use it is enough that the device produces a voltage of 60 V and can provide a current of 120-160 A. Therefore for primary, to which a 220 V household network is connected, you will need a wire with a cross-section from 3 mm 2 to 4 mm 2. But ideal option- this is a conductor with a cross section of 7 mm 2. With such a cross-section, voltage drops and possible additional loads will not be a problem for the device. It follows from this that the secondary requires a conductor 3 mm in diameter. If we take an aluminum conductor, then the calculated cross-section of the copper conductor is multiplied by a factor of 1.6. For secondary you will need a copper busbar with a cross-section of at least 25 mm 2

It is very important that the winding conductor is covered with rag insulation, since traditional PVC sheathing melts when heated, which can cause an inter-turn short circuit.

If you do not find a wire with the required cross-section, then you can make it yourself from several more thin conductors. But this will significantly increase the thickness of the wire and, accordingly, the dimensions of the unit.

First of all, the base of the transformer is manufactured - the core. It is made from metal plates (transformer steel). These plates should have a thickness of 0.35-0.55 mm. The pins connecting the plates must be well insulated from them. Before assembling the core, its dimensions are calculated, that is, the dimensions of the “window” and the cross-sectional area of ​​the core, the so-called “core”. To calculate the area, use the formula: S cm 2 = a x b (see figure below).

But from practice it is known that if you make a core with an area of ​​less than 30 cm 2, then it will be difficult to obtain a high-quality seam with such a device due to a lack of power reserve. Yes, and it will heat up very quickly. Therefore, the cross-section of the core must be at least 50 cm 2. Despite the fact that the weight of the unit will increase, it will become more reliable.

To assemble the core it is better to use L-shaped plates and place them as shown in the following figure until the thickness of the part reaches the required value.

Upon completion of assembly, the plates must be fastened together (at the corners) with bolts, then cleaned with a file and insulated with fabric insulation.

Now we can start winding the transformer.

One nuance should be taken into account: the ratio of turns on the core should be 40% to 60%. This means that on the side where the primary is located there should be a smaller number of secondary turns. Due to this, when welding begins, the winding with more turns will be partially switched off due to the occurrence of eddy currents. At the same time, the current strength will increase, which will have a positive effect on the quality of the seam.

When the winding of the transformer is completed, the network cable is connected to the common wire and to the 215 turn branch. Welding cables are connected to the secondary winding. After this, the contact welding machine is ready for use.

DC device

To cook cast iron or stainless steel, you need a direct current apparatus. It can be made from a conventional transformer unit, if its secondary winding connect the rectifier. Below is a diagram of a welding machine with a diode bridge.

Diagram of a welding machine with a diode bridge

The rectifier is assembled using D161 diodes capable of withstanding 200A. They must be installed on radiators. Also, to equalize the current ripple, you will need 2 capacitors (C1 and C2) of 50 V and 1500 μF. This electrical circuit also has a current regulator, the role of which is played by inductor L1. Welding cables are connected to contacts X5 and X4 (straight or reverse polarity), depending on the thickness of the metal being connected.

Inverter from computer power supply

It is impossible to make a welding machine from a computer power supply. But using its case and some parts, as well as the fan, is quite possible. So, if you make an inverter with your own hands, you can easily place it in the power supply case from the computer. All transistors (IRG4PC50U) and diodes (KD2997A) must be installed on radiators without using gaskets. For cooling parts it is desirable use powerful fan , such as Thermaltake A2016. Despite its small dimensions (80 x 80 mm), the cooler is capable of reaching 4800 rpm. The fan also has a built-in speed controller. The latter are regulated using a thermocouple, which must be mounted on a radiator with installed diodes.

Advice! It is recommended to drill several additional holes in the power supply housing for better ventilation and heat removal. The overheat protection installed on the transistor radiators is set to operate at a temperature of 70-72 degrees.

Below is the circuit diagram welding inverter(in high resolution), which can be used to make a device that fits in the power supply housing.

The following photos show what components a homemade inverter welding machine consists of, and what it looks like after assembly.

Electric motor welder

To make a simple welding machine from an electric motor stator, you need to select the motor itself that meets certain requirements, namely, that its power should be from 7 to 15 kW.

Advice! It is best to use a 2A series motor because it will have a large flux window.

You can get the required stator in places where scrap metal is accepted. As a rule, it will be cleared of wires and after a couple of blows with a sledgehammer it will split. But if the case is made of aluminum, then in order to remove the magnetic core from it, you will need to anneal the stator.

Preparing for work

Place the stator with the hole facing up and place bricks under the part. Next, put the wood inside and set it on fire. After a couple of hours of frying, the magnetic circuit will easily separate from the body. If there are wires in the housing, they can also be removed from the grooves after heat treatment. As a result, you will receive a magnetic circuit cleared of unnecessary elements.

This blank should be well impregnate with oil varnish and let it dry. To speed up the process you can use heat gun. Impregnation with varnish is done so that after removing the ties the bag does not crumble.

When the blank is completely dry, using a grinder, remove the zip ties, located on it. If the ties are not removed, they will act as short-circuited turns and take power from the transformer and also cause it to heat up.

After cleaning the magnetic circuit from unnecessary parts, you will need to make two end plates(see picture below).

The material for their manufacture can be either cardboard or pressboard. You also need to make two sleeves from these materials. One will be internal, and the second will be external. Next, you need:

• install both end plates on the blank;
• then insert (put on) the cylinders;
• wrap this entire structure with keeper or glass tape;
• saturate the resulting part with varnish and dry.

Transformer manufacturing

After carrying out the above steps, it will be possible to make a welding transformer from the magnetic core. For these purposes, you will need a wire covered with fabric or glass enamel insulation. To wind the primary winding, you will need a wire with a diameter of 2-2.5 mm. The secondary winding will require about 60 meters of copper busbar (8 x 4 mm).

So, the calculations are done as follows.

1. 20 turns of wire with a diameter of at least 1.5 mm should be wound around the core, after which a voltage of 12 V should be applied to it.
2. Measure the current flowing in this winding. The value should be about 2 A. If the value obtained is greater than the required one, then the number of turns should be increased, if the value is less than 2 A, then reduced.
3. Count the number of turns obtained and divide it by 12. As a result, you will get a value that indicates how many turns are needed per 1 V of voltage.

For primary winding A conductor with a diameter of 2.36 mm is suitable, which needs to be folded in half. In principle, you can take any wire with a diameter of 1.5-2.5 mm. But first you need to calculate the cross-section of the conductors in the turn. First you need to wind the primary winding (at 220 V), and then the secondary. Its wire must be insulated along its entire length.

If you make a tap in the secondary winding in the area where 13 V is obtained and install a diode bridge, then this transformer can be used instead of a battery if you need to start the car. For welding, the voltage on the secondary winding should be in the range of 60-70 V, which will allow the use of electrodes with a diameter of 3 to 5 mm.

If you have laid both windings, and in this design there is only free space, then you can add 4 turns of copper busbar (40 x 5 mm). In this case you will receive a winding for spot welding, which will allow you to connect sheet metal up to 1.5 mm thick.

For case manufacturing It is not recommended to use metal. It is better to make it from PCB or plastic. In the places where the coil is attached to the body, it is necessary to lay rubber gaskets to reduce vibration and better insulate from conductive materials.

Homemade spot welding machine

A ready-made spot welding machine has a fairly high price, which does not justify its internal “stuffing”. It is designed very simply, and making it yourself will not be difficult.

To make your own spot welding machine, you will need one transformer from a microwave oven with a power of 700-800 W. You need to remove the secondary winding from it in the manner described above in the section where the manufacture of a welding machine from a microwave was discussed.

A spot welding machine is made in the following way.

1. Make 2-3 turns inside the manipulator with a cable with a conductor diameter of at least 1 cm. This will be the secondary winding, allowing you to obtain a current of 1000 A.
   
   
2. It is recommended to install copper lugs at the ends of the cable.
   
   
3. If we connect 220 V to the primary winding, then on the secondary winding we will get a voltage of 2 V with a current of about 800 A. This will be enough to melt an ordinary nail in a few seconds.
   
   

   

4. Next comes make a housing for the device. Good for foundation wooden board, from which several elements should be made, as shown in the following figure. The dimensions of all parts can be arbitrary and depend on the dimensions of the transformer.
   
   

   

5. To give the case a more aesthetic appearance, sharp corners can be removed using hand router with an edge molding cutter installed on it.
   
   

   

6. On one part of the welding jaws it is necessary cut a small wedge. Thanks to it, the ticks will be able to rise higher.
   
   

   

7. Cut to back wall housing holes for the switch and network cable.
   
   
8. When all the parts are ready and sanded, they can be painted with black paint or varnished.
   
   
9. You will need to disconnect the power cable and limit switch from the unnecessary microwave. You will also need a metal door handle.
   
   

   

10. If you don’t have a switch and a copper rod lying around at home, as well as copper clamps, then these parts need to be purchased.
    
    
11. Cut 2 small rods from the copper wire, which will serve as electrodes, and secure them in the clamps.
    
    

    

12. Screw the switch to the back wall of the device.
    
    
13. Screw the back wall and 2 posts to the base, as shown in the following photos.
    
    

    

14. Attach the transformer to the base.
    
    
15. Next, one network wire is connected to the primary winding of the transformer. The second power wire is connected to the first terminal of the switch. Then you need to attach the wire to the second terminal of the switch and connect it to the other terminal of the primary. But a break should be made on this wire and installed in it breaker removed from microwave. It will act as a welding start button. These wires must be long enough to accommodate the breaker at the end of the clamp.
16. Attach the cover of the device with the installed handle to the stands and back wall.
    
    
17. Secure the side walls of the housing.
    
    
18. Now you can install the welding gun. First, drill holes at their ends into which the screws will be screwed.
    
    
19. Next, attach a switch to the end.
    
    
20. Insert the pliers into the body, first placing them between them for alignment. square block. Drill holes through the side walls of the pliers and insert long nails into them to serve as axles.
    
    

    

21. Attach copper electrodes to the ends of the pliers and align them so that the ends of the rods are opposite each other.
    
    

    

22. To make the top electrode rise automatically, screw in 2 screws and attach an elastic band to them, as shown in the following photos.
    
    

    

23. Turn on the unit, connect the electrodes and press the start button. You should see electrical discharge between copper rods.
    
    
24. To check the operation of the unit, you can take metal washers and weld them.
    
    

    

In this case, the result was positive. Therefore, the creation of a spot welding machine can be considered complete.

Inverter welding is modern device, which is widely popular due to the light weight of the device and its dimensions. The inverter mechanism is based on the use of field-effect transistors and power switches. To become the owner of a welding machine, you can visit any tool store and get one useful thing. But there is a much more economical way, which is due to the creation of inverter welding with your own hands. It is the second method that we will pay attention to in this material and consider how to do welding at home, what you will need for this and what the diagrams look like.

Features of the inverter operation

An inverter-type welding machine is nothing more than a power supply, the one that is now used in modern computers. What is the operation of the inverter based on? The following picture of electrical energy conversion is observed in the inverter:

2) Current with a constant sinusoid is converted into alternating current with a high frequency.

3) The voltage value decreases.

4) The current is rectified while maintaining the required frequency.

A list of such electrical circuit transformations is necessary in order to be able to reduce the weight of the device and its overall dimensions. After all, as you know, old welding machines, the principle of which is based on reducing the voltage and increasing the current on the secondary winding of the transformer. As a result, due to the high current value, the possibility of arc welding of metals is observed. In order for the current to increase and the voltage to decrease, the number of turns on the secondary winding is reduced, but the cross-section of the conductor is increased. As a result, you can notice that a transformer-type welding machine not only has significant dimensions, but also a decent weight.

To solve the problem, an option was proposed for implementing a welding machine using an inverter circuit. The principle of the inverter is based on increasing the frequency of the current to 60 or even 80 kHz, thereby reducing the weight and dimensions of the device itself. All that was required to implement an inverter welding machine was to increase the frequency thousands of times, which became possible thanks to the use of field-effect transistors.

Transistors provide communication with each other at a frequency of about 60-80 kHz. The transistor power supply circuit receives a constant current value, which is ensured by the use of a rectifier. A diode bridge is used as a rectifier, and capacitors provide voltage equalization.

Alternating current that is transferred after passing through transistors to a step-down transformer. But at the same time, a coil that is hundreds of times smaller is used as a transformer. Why a coil is used is because the frequency of the current that is supplied to the transformer is already increased 1000 times thanks to field effect transistors. As a result, we obtain similar data as with transformer welding, only with big difference in weight and dimensions.

What is needed to assemble an inverter

To assemble inverter welding yourself, you need to know that the circuit is designed, first of all, for a consuming voltage of 220 Volts and a current of 32 Amps. After energy conversion, the output current will increase almost 8 times and reach 250 Amperes. This current is sufficient to create a strong seam with an electrode at a distance of up to 1 cm. To implement an inverter-type power supply, you will need to use the following components:

1) A transformer consisting of a ferrite core.

2) Winding of the primary transformer with 100 turns of wire with a diameter of 0.3 mm.

3) Three secondary windings:

— internal: 15 turns and wire diameter 1 mm;

- medium: 15 turns and diameter 0.2 mm;

— external: 20 turns and diameter 0.35 mm.

In addition, to assemble the transformer, you will need the following elements:

— copper wires;

- fiberglass;

— textolite;

— electrical steel;

- cotton material.

What does an inverter welding circuit look like?

In order to understand what welding is all about inverter device, you need to consider the diagram presented below.

Electrical circuit of inverter welding

All these components must be combined and thereby obtain a welding machine that will an indispensable assistant when performing locksmith work. Below is circuit diagram inverter welding.

Inverter welding power supply diagram

The board on which the device's power supply is located is mounted separately from the power section. The separator between the power part and the power supply is metal sheet, electrically connected to the unit body.

To control the gates, conductors are used, which must be soldered close to the transistors. These conductors are connected to each other in pairs, and the cross-section of these conductors does not play a special role. The only thing that is important to consider is the length of the conductors, which should not exceed 15 cm.

For a person who is not familiar with the basics of electronics, reading this kind of circuit is problematic, not to mention the purpose of each element. Therefore, if you do not have skills in working with electronics, then it is better to ask a familiar specialist to help you figure it out. For example, below is a diagram of the power part of an inverter welding machine.

Diagram of the power part of inverter welding

How to assemble inverter welding: step-by-step description + (Video)

To assemble an inverter welding machine, you must complete the following work steps:

1) Frame. It is recommended to use an old computer system unit as a housing for welding. It is best suited because it has required quantity holes for ventilation. You can use an old 10-liter canister in which you can cut holes and place the cooler. To increase the strength of the structure, it is necessary to place metal corners, which are secured using bolted connections.

2) Assembling the power supply. An important element The power supply is precisely a transformer. It is recommended to use 7x7 or 8x8 ferrite as the base of the transformer. For the primary winding of the transformer, it is necessary to wind the wire across the entire width of the core. This important feature entails improved operation of the device when voltage surges occur. It is imperative to use PEV-2 copper wires as wire, and if there is no busbar, the wires are connected into one bundle. Fiberglass is used to insulate the primary winding. On top, after the layer of fiberglass, it is necessary to wind turns of shielding wires.

Transformer with primary and secondary windings for creating inverter welding

3) Power section. A step-down transformer acts as a power unit. Two types of cores are used as a core for a step-down transformer: Ш20х208 2000 nm. It is important to provide a gap between both elements, which is solved by placing newsprint. The secondary winding of a transformer is characterized by winding turns in several layers. Three layers of wires must be laid on the secondary winding of the transformer, and fluoroplastic gaskets must be installed between them. It is important to place a reinforced insulating layer between the windings, which will avoid voltage breakdown on the secondary winding. It is necessary to install a capacitor with a voltage of at least 1000 Volts.

Transformers for the secondary winding from old TVs

To ensure air circulation between the windings, it is necessary to leave an air gap. A current transformer is assembled on a ferrite core, which is connected to the circuit to the positive line. The core must be wrapped with thermal paper, so it is best to use cash register tape as this paper. Rectifier diodes are attached to the aluminum radiator plate. The outputs of these diodes should be connected with bare wires with a cross-section of 4 mm.

3) Inverter unit. The main purpose of an inverter system is to convert direct current into high-frequency alternating current. To ensure an increase in frequency, special field-effect transistors are used. After all, it is the transistors that work to open and close at high frequencies.

It is recommended to use more than one powerful transistor, but it is best to implement a circuit based on 2 less powerful ones. This is necessary in order to be able to stabilize the current frequency. The circuit cannot do without capacitors, which are connected in series and make it possible to solve the following problems:

Aluminum plate inverter

4) Cooling system. Cooling fans should be installed on the case wall, and for this you can use computer coolers. They are necessary to ensure cooling of the working elements. The more fans you use, the better. In particular, it is imperative to install two fans to blow over the secondary transformer. One cooler will blow on the radiator, thereby preventing overheating of the working elements - rectifier diodes. The diodes are mounted on the radiator as follows, as shown in the photo below.

Rectifier bridge on the cooling radiator

Photo of the thermostat

It is recommended to install it on the heating element itself. This sensor will be triggered when reaching critical temperature heating the working element. When it is triggered, the power to the inverter device will be turned off.

Powerful fan for cooling the inverter device

When working inverter welding heats up very quickly, so having two powerful coolers is prerequisite. These coolers or fans are located on the device body so that they work to extract air.

Apply fresh air into the system thanks to the holes in the device body. The system unit already has these holes, and if you use any other material, do not forget to provide a flow of fresh air.

5) Soldering the board is a key factor since the board is what the entire circuit is based on. It is important to install diodes and transistors on the board in opposite directions to each other. The board is mounted directly between the cooling radiators, with the help of which the entire circuit of electrical appliances is connected. The supply circuit is designed for a voltage of 300 V. The additional arrangement of capacitors with a capacity of 0.15 μF makes it possible to dump excess power back into the circuit. At the output of the transformer there are capacitors and snubbers, with the help of which the overvoltages at the output of the secondary winding are suppressed.

6) Setting up and debugging work. After the inverter welding has been assembled, several more procedures will need to be carried out, in particular, setting up the operation of the unit. To do this, connect a voltage of 15 volts to the PWM (pulse width modulator) and power the cooler. Additionally connected to the relay circuit through resistor R11. The relay is connected to the circuit in order to avoid voltage surges in the 220 V network. It is imperative to monitor the relay’s activation, and then apply power to the PWM. As a result, a picture should be observed in which rectangular areas on the PWM diagram should disappear.

The device of a homemade inverter with a description of the elements

You can judge whether the circuit is connected correctly if the relay outputs 150 mA during setup. If a weak signal is observed, this indicates that the board connection is incorrect. There may be a breakdown in one of the windings, so to eliminate interference you will need to shorten all power supply wires.

Inverter welding in a computer system case

Checking the device's functionality

After all the assembly and debugging work has been completed, all that remains is to check the functionality of the resulting welding machine. To do this, the device is powered from a 220 V electrical network, then it is set high performance current strength and the readings are verified using an oscilloscope. In the lower loop, the voltage should be within 500 V, but not more than 550 V. If everything is done correctly with a strict selection of electronics, then the voltage indicator will not exceed 350 V.

So, now you can check the welding in action, for which we use the necessary electrodes and cut the seam until the electrode burns out completely. After this, it is important to monitor the temperature of the transformer. If the transformer simply boils, then the circuit has its shortcomings and it is better not to continue the work process.

After cutting 2-3 seams, the radiators will heat up to high temperature, so it is important to allow them to cool after this. To do this, a 2-3 minute pause is enough, as a result of which the temperature will drop to the optimal value.

Checking the welding machine

How to use a homemade device

After being connected to the circuit homemade apparatus, the controller will automatically set a certain current strength. If the wire voltage is less than 100 Volts, this indicates a malfunction of the device. You will have to disassemble the device and recheck the correct assembly again.

Using this type welding machines You can solder not only ferrous, but also non-ferrous metals. In order to assemble a welding machine, you will need not only knowledge of the basics of electrical engineering, but also free time to implement the idea.

Inverter welding is an indispensable thing in any owner’s garage, so if you have not yet acquired such a tool, then you can make it yourself.

Direct current will require a high-power source of electric current, which converts the standard household voltage and ensures a constant value of the electric current to ignite and maintain the electric arc.

A DC welding machine has a number of advantages: soft arc ignition and the ability to connect thin-walled parts.

Block diagram of the apparatus for welding work

The power supply is installed in a housing made of plastic or sheet metal. The unit's power supply is equipped with all components necessary for operation: connectors, switches, terminals and regulators. Unit housing for implementation welding work equipped with special holders and wheels for transportation.

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The main condition when designing a unit used for welding is an understanding of the operating principle of the device and the essence of the welding process itself. In order to design a welding machine yourself, you need to understand the principles of ignition and combustion of an electric arc and the basic principles of melting an electrode for welding.

The high power power supply includes components such as:

• rectifier;
• inverters;
• current and voltage transformer;
• regulators that contribute to improvement quality characteristics the resulting electric arc;
• additional facilities.

The main component of any welding machine is the transformer. Assistive devices may have different scheme organization depending on the design of the device.

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Transformer for welding

A DC welding machine in its design includes a transformer as its main element, which reduces the normal mains voltage from 220 V to 45-80 V.

This structural element operates in arc mode with maximum power.

Transformers used in the design must withstand high current values ​​during operation, the rated strength of which is 200 A. The voltage-ampere indicators of the transformer must fully comply with the special requirements that ensure the operating modes of arc welding.
Some homemade transformer welding machines are simple in design. They do not have additional devices for adjusting current parameters. Adjustment of the technical parameters of such a device is carried out in several ways:

• using a highly specialized regulator;
• by switching the number of coil turns.

The transformer of the welding unit consists of the following structural elements:

• magnetic circuit made of transformer steel plates;
• two windings - primary and secondary, this transformer component has terminals for connecting devices for adjusting operating current parameters.

The transformer used in the welding machine does not have control devices that provide current regulation and limitation on the working winding. Primary winding welding transformer is equipped with terminals for connecting control circuits and devices that allow you to configure the welding device depending on operating conditions and parameters of the incoming current.

The main part of the transformer is the magnetic circuit. Most often, when constructing homemade welding machines, magnetic cores from a decommissioned engine, an old power transformer. Each magnetic circuit design has its own design nuances. The main parameters characterizing the magnetic circuit are the following:

• magnetic core size;
• number of turns of windings on the magnetic core;
• voltage level at the input and output of the device;
• current consumption level;
• the maximum current received at the output of the device.

These basic characteristics determine the suitability of the transformer for use as a device that promotes the formation of an arc, as well as a device that promotes the formation of a quality weld.

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Possible details when creating a welding machine

When creating a welding machine with your own hands, the stability of the electric arc is achieved by constant potential. The stability of the arc ensures the quality of the resulting seams. Constant potential is achieved by using high-power rectifiers, which are carried out on diodes that can withstand currents of up to 200 A, such as, for example, the B-200.

These diodes are large and require mandatory use for organizing high-quality heat removal of massive radiators. This circumstance must be taken into account when manufacturing the structure body. The best option When creating the design, a special diode bridge will be used. The diodes can be mounted in parallel, which significantly increases the output current.

When assembling a structure with your own hands, you need to adjust all its components. If the selection is poor or incorrectly calculated, the design can affect the quality of welding.

Sometimes, with the appropriate selection of parts and components, a truly unique device can be obtained, which has a soft and easy ignition of the electric arc, and welding of parts can be carried out even with very thin walls, with almost no splashing of liquid metal.

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Schematic diagram of a homemade welding unit

You can make a homemade welding machine based on transistor or thyristor control. Thyristors are more reliable. These control design elements are able to withstand a short circuit at the output and are able to recover from this condition quite quickly. These control system components do not require the installation of powerful cooling radiators. This is due to the fact that structural elements have low heat generation.

A control system created on transistors is capable of leaving the operating state much faster, since transistors burn out much faster when overloads occur and are more capricious in operation. The circuit, created on the basis of thyristors, is simple and highly reliable.

A control unit based on these elements has the following advantages:

• smooth adjustment;
• presence of direct current.

When welding steel 3 mm thick, the current consumption is about 10 A. The welding current is supplied by pressing a special lever on the fork that holds the electrode.

This design makes it possible to increase safety during work and to work with high voltage, which ensures stable arc burning. If reverse polarity is used in the work, it is possible to carry out welding work with very thin sheet metal.