How to make a welding machine in 15 minutes

2 options for assembling a simple welding machine

Nowadays, it is difficult to imagine any work with metal without the use of a welding machine. Using this device, you can easily connect or cut iron of various thicknesses and dimensions. Naturally, to perform high-quality work you will need certain skills in this matter, but first of all you need the welder itself.

Nowadays, of course, you can buy it, as well as, in principle, hire a welder, but in this article we will talk about how to make a welding machine with your own hands. Moreover, with all the wealth of different models, reliable ones are quite expensive, and cheap ones do not shine with quality and durability.

But even if you decide to buy a welder in a store, reading this article will help you choose the necessary device, since you will know the basics of their circuitry. There are several types of welders: direct current, alternating current, three-phase and inverter.

In order to determine which option you need, we will consider the design and device of the first two types, which you can assemble with your own hands at home without any specific skills.

AC

This type of welding machine is one of the most common options, both in industry and in private households.

It is easy to use and, compared to others, can be made quite easily at home, as evidenced by the photo below.

To do this, you need to have a wire for the primary and secondary windings, as well as a transformer steel core for winding the welder. In simple words, an AC welding machine is a high-power step-down transformer.

The optimal voltage when operating a welding machine assembled at home is 60V. The optimal current is 120-160A. Now it’s easy to calculate what cross-section the wire should have in order to make the primary winding of the transformer (the one that will be connected to the 220 V network). The minimum cross-sectional area of ​​the copper wire should be 3-4 square meters. mm, the optimal is 7 sq.

mm, because it is necessary to take into account voltage drops and possible additional load, as well as the necessary safety margin. We find that the optimal diameter of the copper core for the primary winding of a step-down transformer should be 3 mm.

If you decide to take an aluminum wire to make a welding machine with your own hands, then the cross-section for the copper wire must be multiplied by a factor of 1.6.

It is important that the wires are covered in rag braid; conductors in PVC insulation cannot be used - when the wires heat up, it will melt and a short circuit will occur. If you do not have a wire of the required diameter, you can use thinner wires, winding them in parallel.

But then it should be taken into account that the thickness of the winding will increase, and, accordingly, the dimensions of the device itself. It must be borne in mind that the limiting factor may be a free window in the core and the wire may simply not fit there. For the secondary winding, you can use a thick stranded copper wire - the same as the core on the holder.

Its cross-section should be selected based on the current in the secondary winding (remember that we are focusing on 120 - 160A) and the length of the wires.

The first step is to make a transformer core for a homemade welding machine. The best option would be a rod-type core as shown in Figure 1:

This core must be made from transformer steel plates. The thickness of the plates should be from 0.35 mm to 0.55 mm. This is necessary to reduce Foucault currents. Before assembling the core, you need to calculate its dimensions, this is done as follows:

• First, the window size is calculated. Those. Dimensions c and d in Figure 1 must be chosen such as to accommodate all the windings of the transformer.
• Secondly, the roll area, which is calculated by the formula: Roll = a*b, must be at least 35 square meters. cm. If there is more Skren, then the transformer will heat up less and, accordingly, work longer, and you will not need to interrupt often in order for it to cool down. It is better that the Skrena is equal to 50 square meters. cm.

Next, we proceed to assembling the plates of a homemade welding machine. It is necessary to take the L-shaped plates and fold them, as shown in Figure 2, until you can make a core of the required thickness. Then we fasten it with bolts at the corners. Finally, it is necessary to process the surface of the plates with a file and insulate them by wrapping them with rag insulation in order to further protect the transformer from breakdown to the housing.

Next, we proceed to winding the welding machine from the step-down transformer. First, we wind the primary winding, which will consist of 215 turns, as shown in Figure 3.

It is advisable to make a branch from 165 and 190 turns. We attach a thick textolite plate to the top of the transformer.

We fix the ends of the windings on it using a bolted connection, noting that the first bolt is a common wire, the second is a branch from the 165th turn, the 3rd is a branch from the 190th turn and the 4th is from the 215th.

This will make it possible to subsequently regulate the current during welding by switching between different terminals of your welding device. This is a very important function, and the more branches you make, the more precise your adjustment will be.

Then we proceed to winding 70 turns of the secondary winding, as shown in Figure 4.

A smaller number of turns are wound on the other side of the core - where the primary winding is wound. The ratio of turns should be approximately 60% to 40%. This ensures that after you catch the arc and start welding, the eddy currents will partially turn off the operation of the winding with a large number of turns, which will lead to a decrease in the welding current, and accordingly improve the quality of the seam.

This way the arc will be easy to catch, but too much current will not interfere with quality welding. We will also secure the ends of the winding with bolts to the textolite plate. You can not attach them, but run the wires directly to the electrode holder and the crocodile to ground; this will remove connections where there could potentially be a voltage drop and heating.

For better cooling, it is highly advisable to install a fan for blowing, for example from a refrigerator or microwave.

Now your homemade welding machine is ready. Having connected the holder and ground to the secondary winding, it is necessary to connect the network to the common wire and the wire extending from the 215th turn of the primary winding.

If you need to increase the current, you can make fewer turns of the primary winding by switching the second wire to a contact with fewer turns. The current can be reduced using a resistance made from a piece of transformer steel bent into a spring and connected to a holder.

It is always necessary to ensure that the welding machine does not overheat; to do this, regularly check the temperature of the core and windings. For these purposes, you can even install an electronic thermometer.

This is how you can make a welding machine from a step-down transformer with your own hands. As you can see, the instructions are not too complicated and even an inexperienced electrician can assemble the device on their own.

DC

Some types of welding require a DC welder. This tool can be used to weld cast iron and stainless steel. You can make a DC welding machine with your own hands in no more than 15 minutes by remaking a homemade product using alternating current. To do this, you need to connect a rectifier assembled with diodes to the secondary winding. As for the diodes, they must withstand a current of 200 A and have good cooling. D161 diodes are suitable for this.

Capacitors C1 and C2 with the following characteristics will help us equalize the current: capacitance 15000 μF and voltage 50V. Next, we assemble the circuit shown in the drawing below. Inductor L1 is needed to regulate the current. Contacts x4 are plus for connecting the holder, and x5 are minus for supplying current to the part to be welded.

Three-phase welding machines are used for welding in industrial conditions, they are equipped with two-electrode holders, so we will not consider them in this article, and inverters are made on the basis of printed circuit boards and complex circuits with a large number of expensive radio components and a complex setup process using special equipment. However, we still recommend that you familiarize yourself with the inverter design in the video below.

Visual master classes

So, if you decide to make a welding machine at home, we recommend watching the video lessons provided below, which will clearly show how to assemble a simple welder yourself from scrap materials, and will also explain to you some of the details and nuances of the work:

Now you know the basic principles of the design of welders and you can make a welding machine with your own hands, both on direct and alternating current, using the instructions from our article.

Also read:

Source: https://samelectrik.ru/2-varianta-sborki-prostogo-svarochnogo-apparata.html

DIY mini welding machine for home use

In the arsenal of a home craftsman there are many tools for all occasions.

A welding machine is an indispensable device for real craftsmen. It can be bought in stores. However, it is much more interesting and cheaper to assemble it yourself.

Some also have a welding machine, which every craftsman dreams of.

Today it can be purchased in specialized stores. There are many models. Various device accessories and consumables are sold. Is it possible to make a welding machine with your own hands? The answer is simple: it is possible and even necessary!

Types of Welding Machines

All welding machines are divided into gas and electric. Gas installations are not entirely suitable for domestic use. They require special treatment, as they are equipped with explosive gas cylinders. Therefore, we should talk only about electrical devices. They are also different:

The welding equipment is economical and ideal for home use.

1. Generators. These installations have their own current generator. They are very heavy and bulky in size. Not suitable for home assembly and use.
2. Transformers. Such devices can be powered from a 220 or 380 volt network. They are very popular, especially semi-automatic ones.
3. Inverters. Very economical devices, ideal for the home. They are lightweight, but have a rather complex electronic circuit.
4. Rectifiers. Easy to make and use. Even novice welders can make quality welds. Ideal for DIY assembly.

Where to start assembling an inverter apparatus?

To assemble the inverter, you need to select a circuit that will provide the necessary operating parameters of the device. It is recommended to use Soviet-made parts. This is especially true for diodes, capacitors, transistors, resistors, chokes, thyristors and finished transformers. The equipment assembled on these parts does not require complex adjustments. All parts are very compactly located on the board. To make the device yourself, you can select the following parameters:

1. The welding machine must work with electrodes with a diameter of up to 4-5 mm.
2. The operating current is no more than 250 A.

Source: https://moyakovka.ru/instrumenty/mini-svarochnyi-apparat-svoimi-rukami.html

Mini welding machine 12 V

With this simple welding machine you can cut thin metals, weld copper wires, and engrave metal surfaces.
Other applications can be found without any problems. This mini welding machine can be powered with a voltage of 12-24 V. The welding machine is based on a high-voltage high-frequency converter.

Built on the principle of a blocking oscillator with deep transformer feedback. The generator generates short-term electrical pulses, repeated at relatively large intervals. The clock frequency is in the range of 10-100 kHz. The transformation ratio of this circuit will be 1 to 25. This means that if a voltage of 20 V is applied to the circuit, then the output should be about 500 V. This is not entirely true.

Since any pulse transformer source or generator without load has powerful high-voltage pulses reaching a voltage of 30,000 V! Therefore, if you disassemble any Chinese pulse charger, you will see a soldered resistor parallel to the output capacitor. This is also a network load; without a resistor, the output capacitor will quickly leak due to excess voltage, or worse, it will explode.

Therefore, attention! The voltage at the transformer output is dangerous to life!

Mini welding machine diagram

Required parts:

• The transformer is homemade, the manufacturing procedure is described below.
• Resistors - 0.5-2 W power.
• The transistor used was FP1016, but it is difficult to find due to its specificity. Can be replaced with transistor 2SB1587, KT825, KT837, KT835 or KT829 by changing the polarity of the power supply. Another transistor with a collector current of 7 A, a collector-emitter voltage of 150 V, and a high gain (composite transistor) is also suitable.

The transistor must have a heat sink installed.

Although this is not on the diagram, it would be a good idea to place a filter capacitor in parallel with the source so that all interference from the operation of the blocking generator does not penetrate the source.

Transformer manufacturing

The transformer is wound on a piece of ferrite rod from a radio receiver.

• The collector winding is 20 turns of 1 mm wire.
• Base winding - 5 turns with a 0.5-1 mm rein.
• High-voltage winding - 500 turns with a drive of 0.14-0.25 mm.

All windings are wound in one direction. First is the collector winding, followed by the base winding. This is followed by three layers of white electrical tape insulation.

Next, we wind the high-voltage winding, 1 layer of 125 turns, then insulation, then repeat. In total, you should get 4 layers, which is equal to 500 turns. We also insulate the top with white electrical tape in several layers.

Let's put together a diagram. If everything is in order, everything should start without problems.

Since the operating frequency of the generator exceeds the sound frequency, you will not hear a squeak during operation, so do not touch the output of the transformer with your hands. Start the generator with a voltage of 12 Volts and increase if necessary. The arc ignites from a distance of 1 cm, which indicates the voltage 30 kV. The high frequency does not allow the burning arc to break, as a result of which the arc burns very stably.

When using a copper electrode in close contact with another electrode, a plasma medium (copper plasma) is formed, resulting in an increase in the temperature of arc welding and cutting.

Welding machine testing by cutting and welding

We cut a razor blade with an arc. We fuse copper wires up to 1 mm thick. Thick copper wire was used as an electrode. It is clamped in a wooden match, since dry wood is also a good insulator.

If you liked this small welding machine, then you can make it larger in size and power. But be extremely careful.

Also, to increase the power, you can assemble a generator using a push-pull circuit, and even using field-effect transistors, like here - Simple 12 V induction heater. In this case, the power will be decent.

Also, do not look at the bright arc discharges with the naked eye; use special safety glasses.

Watch a video of making a welding machine using a blocking generator

The author of the homemade video is Artym Kositsyn

Source: https://SdelaySam-SvoimiRukami.ru/3848-mini-svarochnyy-apparat-12-v.html

DIY welding machine: homemade mini machine at home

When performing simple and small-scale welding work at home, anyone can assemble a welding machine with their own hands.

You don’t have to spend a lot of money, effort and time to assemble. There is also no need to purchase unreasonably expensive models of such equipment.

What do you need to know to assemble a homemade welder?

To make a mini welding machine with your own hands from available materials, without special financial costs and effort, you need to understand how the equipment functions, after which you can start producing it at home.

First of all, it is worth determining the required power supply for homemade welding equipment. Connecting parts of a massive structure requires a higher current intensity, and welding work with thin metal surfaces requires minimal current.

The current value is related to the selected electrodes that will be used in the process. When welding products up to 5 millimeters, it is necessary to use rods up to 4 millimeters, and in a structure with 2 millimeters thick, rods should be 1.5 millimeters.

When using electrodes of 4 millimeters, the current is regulated up to 200 amperes, for 3 millimeters up to 140 amperes, for 2 millimeters - up to 70 amperes, and for the smallest ones up to 1.5 millimeters - up to 40 amperes.

You can form an arc for the welding process yourself using the mains voltage, which is obtained through the operation of a transformer.

This equipment includes:

• magnetic circuit;
• winding – primary and secondary.

You can also make a transformer yourself. For the magnetic circuit, plates made of steel or other durable material are used. Windings are necessary to directly perform welding work and to be able to connect the welding unit to a 220 volt network.

Transformer for welding work.

Specialized equipment has additional devices that improve the quality and power of the arc, which makes it possible to independently regulate the current values.

For welding equipment made at home, it is not necessary to use additional devices. Looking at the value of the current, you can select the power of the transformer, and to calculate the power, you need to multiply the current indicator that is used during operation of the equipment by 25.

The result obtained is multiplied by 0.015, where the result is the required value of the magnetic core diameter. To calculate the required winding cross-section, it is enough to divide the power by 2000, and then multiply the resulting number by 1.13.

To calculate how many turns of wiring need to be wound, you need to divide the cross-sectional area of ​​the magnetic circuit in half.

If you are planning to make a simple welding machine with your own hands, then it should be noted that the welding process itself comes in several types - soft and hard, this is influenced by the voltage that is on the equipment clamp.

Using this parameter, you can set the properties of the external current for the welding process, which is also divided into flat, steep and increasing.

Most experts recommend using current sources with flat or steep characteristics. They have a minimal change in current when the electric arc oscillates, which makes it possible to weld metal at home.

How to make a welding unit with your own hands?

After studying the main features of the assembly process, you can proceed directly to assembling homemade equipment.

Today, there are a large number of different methods and recommendations on how best to assemble a homemade welding machine of any kind - with alternating or direct current, pulsed or inverter, automatic or semi-automatic.

There is no need to go deep enough into this topic, since one of the easiest ways to assemble a welding machine with your own hands is to use a transformer.

To make it you need to prepare:

1. Several meters of cable with great thickness.
2. Material for the core that will be located in the transformer.
   The material itself must have increased permeability with magnetization.

The best option is when the rod-shaped core has the letter “P”. In some cases, it is allowed to use this part in a more modified form, for example, a round stator made from a damaged electric motor.

Diagram of a welding transformer.

However, it is worth paying attention that it is more difficult to wind windings onto this shape. It is best when the core cross-section for classic welding equipment, made by hand and used for domestic purposes, had an area of ​​about 50 cm2.

In order for the equipment to have an accessible weight, it is not necessary to increase the cross-section in volume, however, the technical effect will not be at the highest level. If the cross-sectional area does not suit you, then you can calculate it yourself using special diagrams and formulas.

The primary winding must be made of copper wire, which will have increased characteristics: thermal resistance, since during operation of the structure this part heats up very much.

Such a part must have cotton or fiberglass insulation. As a last resort, it is possible to use rubber insulated wire or rubber cloth, but beware of PVC winding.

The insulation is also made by hand, using cotton or fiberglass, or rather parts of it 2 cm wide. Thanks to these pieces, you can wrap the wire and then impregnate it with any varnish for electrical purposes. This insulation will not overheat after regular use.

Similar to the above calculations, it will be possible to calculate which cross-sectional area of ​​the winding - primary and secondary - will be the most optimal. Often the secondary winding has an area of ​​about 30 mm2, and the primary winding up to 7 mm2, using a rod of 4 millimeters in diameter.

In addition, in a simple way you need to determine how far a piece of copper wire will stretch and how many turns will be needed to wind two windings. After this, the coils are wound, and the frame is made using the geometric parameters of the magnetic core.

The main thing is to ensure that there are no difficulties when putting on the magnetic core. First of all, you need to choose the correct core size. It is best made using electrical cardboard or textolite.

Using the same analogue, it will be possible to make a structure for welding small parts. For home use, you can use a small mini welding machine.

Manufacturing of welding machine

Today it is almost impossible and quite difficult to weld metal or process it in the proper way without using welding equipment. After you make a welding machine with your own hands, you will be able to perform any work with metal products.

Transformer circuit with a separate choke.

To produce a high-quality unit, you must have knowledge and skills that will help you understand the circuit of a DC or AC welding machine, which are two options for assembling equipment.

For home use, it is best to learn how to make mini welding.

It is more convenient to call a specialist or purchase a ready-made unit, but sometimes this can be too expensive, since it is quite difficult to determine the choice of model based on various parameters, such as the weight of the welding machine, and the number of volts per welding machine.

There are several types of welding machines: operating on alternating current, direct current, having three phases or inverter. To choose one of the options and start assembling, you need to consider each circuit of the first 2 types. During the preparatory process, you need to pay attention to the voltage stabilizer.

Recommendations for working with the unit

In order to operate the welding machine for its intended purpose, it is necessary, first of all, to ignite the electric arc. This process is easy and is carried out by the following steps: we bring the tip of the electrode at a certain angle from the side of the metal coating and scratch it along the surface of the structure.

If the action is performed correctly and successfully, a small flash occurs and the material melts, after which the necessary elements can be welded.

When making a mini welding machine with your own hands, you must follow the recommendations for working with it. To weld elements, you need to hold the rod in such a position that it is at a certain distance from each other of the parts being welded. This distance can be equal to the cross-section of the selected electrode.

Often a metal such as carbon steel is connected with direct polar current. However, some alloys can only be welded using reverse current polarity. In addition, it is necessary to carefully monitor the quality of the seam and how the structure is fused.

Diagram of a simple welding machine.

It is worth emphasizing that the alternating current contained in the inverter can be regulated efficiently and smoothly. Often, no difficulties arise in setting up the unit to the required parameters.

With a small current indicator, the seam will turn out to be of poor quality, but you should not set an increased value, since there is a risk of burning the surface.

Upon completion of the welding process, using a homemade product, it is necessary to carefully remove the scale that appears on the seam with light movements, after which it is cleaned with a special brush.

Thanks to this action, you can maintain a pleasant aesthetic appearance of your device. Don’t worry if cleaning the equipment isn’t very successful in the first couple of days. This skill is developed through experience and subject to following all recommendations for proper operation of the structure.

Bottom line

To summarize, it is worth noting that DC welding machines are much easier to assemble and they are also easy to use, due to their low power.

If you follow the necessary recommendations, assembling the welding machine can take no more than half an hour.

Source: https://tutsvarka.ru/oborudovanie/svarochnyj-apparat-svoimi-rukami

DIY mini welding machine

If a person plans to perform small amounts of some simple welding work at home, he can easily make a welding machine with his own hands. Now it is difficult to see any work with metal being carried out without the use of a welding machine.

This device freely cuts or joins iron parts, regardless of its thickness and size. To do welding, you need to have some skills, and, in fact, the machine itself.

You can buy it, you can hire a welder to carry out the necessary work, or you can make the unit yourself.

Before you start creating a welding machine at home, you should understand its structure.

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

The main element of the welder that it consists of is a transformer that powers the arc of the device, controls alternating voltage and controls the quality and magnitude of the current.

Next, connecting wires, switches and regulator sliders, and the necessary terminals are connected to the transformer. All this is contained in a housing and is equipped with handles or wheels for easy portability.

The designs of standard welding machines are very diverse, but the following main types can be distinguished:

• AC apparatus;
• Working with direct current;
• Three-phase;
• Inverter.

DC welding is usually used to work with thin sheet material, automotive and roofing steel.

Welding devices of direct and alternating current are reliable, unpretentious in operation, heavy in weight and very sensitive to voltage changes. If it drops below 200 volts, it will be difficult to operate and there will be problems with ignition and maintaining the arc.

These welding machines are very similar in design, and if we have alternating current welding, then by modifying it a little, we will get a device for working with direct current.

As for inverters, thanks to the use of electronic parts, their weight has become much lighter. They are not afraid of voltage drops, but are very sensitive to overheating. You need to work with such devices carefully, otherwise they may break.

Homemade AC welding machine

A welding unit operating with alternating current is one of the most common models. It is the easiest to use and easy to assemble at home compared to other types of welders.

What is needed for this:

• Wires for secondary and primary windings;
• Winding core;
• Step-down transformer (you can take "LATRA").

What wires are needed? The optimal voltage when operating a device created independently is 60V with an optimal current of 120 -160A. Based on this, we understand that the minimum cross-section of copper wires to wind the primary should be 3-4 square meters. mm. Optimal – 7 sq. mm, which takes into account possible additional load and voltage surges.

Do not use wires with PVC or rubber insulation, as they may overheat and cause a short circuit.

If there is no wire of the required cross-section, you can use thin wires wound together. True, the thickness of the winding will increase, which will entail an increase in the dimensions of the device itself. To make a secondary winding, you can take a thick copper wire consisting of many cores.

The homemade core is made from a transformer steel plate, the thickness of which should be from 0.35 mm to 0.55 mm. They must be folded so that a core of the required thickness is obtained, and then the device must be secured with bolts at the corners. At the end of the work, you should use a file to process the surface of the plates and make insulation.

Then the winding begins. First, the primary one (about 240 turns can be made). In order to be able to regulate the passing current, you need to make several taps with an approximate step of 20-25 turns.

How much copper is needed for the secondary winding? Typically the number of turns is 65-70. Wire cross-section – 30 – 35 sq mm. As with the primary winding, taps must be made to regulate the current. The insulation of the wires must be reliable and resistant to heat.

Winding is done in one direction and each layer is insulated. The ends of the winding are bolted to the plate and we can assume that the homemade welder is ready.

When creating a welding machine, you must remember to ground it, in accordance with safety regulations. You should also always ensure that the welding machine does not overheat!

Simple DC Welding Machine

To weld cast iron and stainless steel, you will need a machine with direct current. You can create it in 15 minutes if you already have an AC device. In this case, an existing device will be upgraded.

First of all, you should decide on the current power of the homemade welding machine

Remaking the alternator will consist of connecting a rectifier, which is assembled using diodes, to the secondary winding. The diodes, in turn, must withstand a current of 200 A and be well cooled.

The rectifier will do its job better if you use 50V capacitors and a special inductor to regulate the current.

What you need to know when connecting the device to the network permanently:

• It is imperative to use a switch, which can disconnect the device from the network at any time;
• The cross-section of the wire for connection must be greater than or equal to 1.5 square meters. mm, and the current consumption in the primary winding is a maximum of 25 A.

The way a welder works is such that he needs to be given a rest from time to time. And it doesn’t matter whether it’s a semi-automatic or a handbrake. However, if the device operates on electrodes with a diameter of less than 3 mm, then there is no need to interrupt.

Inverter: how to make a welding machine with your own hands

You can assemble an inverter yourself from small parts and wiring from a Soviet TV or vacuum cleaner.

Features of the inverter:

• The device operates with direct current and its smooth adjustment from 40 to 130 A;
• The highest current for the primary winding is 20A, the electrodes used should be no more than 3 mm;
• The electric holder must have a button, pressing which will supply voltage to the device.

All elements of the inverter are located on a special printed circuit board, and for better heat removal from the diodes, they are fixed to a special heat sink, which is screwed to the board. The board itself is usually made of fiberglass, approximately 1.5 mm thick.

For additional cooling of the circuit, you can use a fan fixed directly to the case in which the inverter is located.

With the help of such a device, you can safely weld non-ferrous and ferrous metals and thin sheet workpieces.

Three-phase welding machines are usually used for welding in industrial settings, so it makes no sense to make them at home.

Particularly popular are welders from Timval, Budyonny and thyristors.

Tips on how to make a welding machine at home: spot welding

One of the most convenient and economical mini weldings has recently become spot welding, which occurs by contact method. In everyday life, such a thing is used for repairing household appliances and welding batteries.

The easiest to manufacture are AC resistance spot welding machines with unregulated current.

Heating occurs using a pulse, and the pulse moment does not exceed one tenth of a second, that is, everything happens very quickly.

This type of mini-welding is created using a transformer from an old microwave, which will be modified during the creation of the device. The goal is the ability to obtain a short-term pulse at the output of at least 1000A.

The modification goes like this:

• Everything is removed from the transformer except the core and primary winding;
• A wire with a cross-section of at least 100 square meters is wound in place of the secondary winding. mm;
• The main thing here is to wrap the wire very tightly around the core.

As a result, the output should be about 5 volts, but if the power is too low, you can use another transformer. Then you need to check the voltage again. If it is no more than 2000 A, the microwelding machine is ready for use.

How to make a welding machine with your own hands (video)

When using electrical wiring and working with a welding machine, you must remember to follow safety precautions. However, it must always be followed, regardless of whether you are creating welding or a cunning milking machine. Before you begin this kind of work, you should always familiarize yourself with how to perform it correctly.

Source: https://steelfactoryrus.com/mini-svarochnyy-apparat-svoimi-rukami/