Do-it-yourself welding machine: how to make it at home. DIY Welding Machine for Welding Small Parts Small Welding Machine

Welding equipment is one of the most used in modern industrial production and at home among those who love and know how to work with their hands. Modern devices have become quite compact. First of all, we are talking about inverter devices.

Due to the high frequency AC conversion, a very small transformer is required. Thanks to inverters, do-it-yourself welding has become more affordable, and the devices themselves have acquired mini sizes. You can also find useful mini spot welding machines.

In everyday life, compact welding machines are especially in demand. For home conditions, long-term operation of the device is usually not required, sometimes one electrode is enough to weld something.

In addition, mini welding is perfect for working at heights, because the mini welding machine can be quickly and easily lifted up. Here a semi-automatic device is not needed, manual arc welding is enough.

For small jobs, lightweight inverter devices are produced. They weigh in the range of 2.5-6 kg, have a welding current of up to 200 A, dimensions are within 20x20x30 cm. To facilitate carrying and working in uncomfortable places, the devices have belts.

In addition to arc, there are also gas mini welding machines. They can fit in a suitcase. The kit usually includes small oxygen bottles, a burner and hoses.

Advantages and disadvantages

The small welding machine is primarily convenient for transportation and storage. Small dimensions and weight, the presence of a belt allow welding in hard-to-reach places. You can work with it almost everywhere, the only requirement is the presence of a 220 V network.

The devices provide adjustment of the welding current. Special stabilizers provide a stable burning of the electric arc, which allows you to get a high-quality weld.

For beginner welders, these are very convenient devices. Compared to professional welding equipment, mini devices have a low cost.

The disadvantages are closely related to the advantages. Small dimensions and weight do not allow to create devices of high power. As a result, the inability to work with electrodes of large diameters.

It is impossible to weld thick-walled workpieces, since there is not enough welding current for this. At extreme operating conditions, problems arise due to overheating of the equipment. The small size greatly limits the functionality of the mini welding machine.

Details and working principle

A mini inverter welding machine is made using the following parts:

bridge rectifier of the input mains voltage on powerful diodes;
soft start relay;
welding current sensor;
high frequency generator;
transformer;
integral stabilizer;
low pass filter;
radiators for diodes and transistors;
cooling system.

The work takes place according to the following scheme. Alternating current 220 V is supplied to the diode rectifier and becomes constant. Then, with the help of a generator, it turns into a high-frequency current. The resulting alternating current enters the primary winding of the transformer.

Since the transformer is step-down, the output is low voltage, but sufficient to ignite the arc. The high frequency current is again converted to direct current by the rectifier.

With its help, metal products are cooked. Due to the presence of an integral stabilizer, regardless of the quality of the mains voltage, the required stable voltage value is obtained at the output.

Characteristics of some models

The concept of mini is transformed over time. More recently, all inverter machines could be categorized as mini compared to transformer-based traditional welding machines.

Now inverter welding machines have become a kind of standard, and only smaller devices are called mini machines.

The inverter device "Special mini 210" belongs to the mini category. It weighs only 2.5 kg and has compact dimensions of 190x200x290 mm. The maximum welding current is 210 A, power consumption 6 kW, voltage 220 V.

The older model "Spets mini 250" has a welding current of 250 A, a power consumption of 8 kW, is powered by a 220 V household network, and weighs 4.2 kg.

The Raduga 180 mini device has a welding current of 180 A, a power of 5 kW and a weight of 6 kg. All welding machines can weld with electrodes from 1.6 to 4 mm. Some of the best in this class are welding machines from the Finnish manufacturer Kemppi, for example, the Kemppi Minarc 150VRD model.

This device is capable of operating in manual and argon arc welding modes. It automatically corrects the arc parameters, and any electrodes can be used, there are no special requirements.

The device can work in conditions of high humidity and dust, at negative and positive temperatures. Has small dimensions and weight about 4 kg.

It is difficult to say which model of the welding machine is the smallest in the world, since many companies already produce such devices. Moreover, the price range is quite wide. Chinese models are considered the most affordable.

If the operating instructions are followed, the mini equipment will last a long time. The main thing is not to exceed the maximum welding time, use only the recommended brands and diameters of electrodes, constantly monitor the cooling system.

DIY manufacturing

Often, a lot of old appliances such as televisions, microwaves and other electrical goods accumulate in the household. If desired, their parts can be used to make useful devices for welding.

Spot welding

The easiest option is to use spot welding. Sometimes you need to connect small, thin metal objects. This is where spot welding comes in handy.

It is necessary for welding a nickel plate to a laptop lithium battery during repairs. The main components required for manufacturing:

low power transformer;
diode bridge;
capacitor bank;
automatic 20A;
powerful current relay;
two copper bars (tips from soldering irons).

To make a mini welding machine, you need to remove the secondary winding from the transformer. Instead, three turns are wound.

The secondary winding is connected to a diode rectifier. Its output is connected to a bank of capacitors connected in parallel. The outputs of the capacitors are connected through a relay to copper electrodes.

Welding is carried out in two stages. The first step is to charge the capacitor bank. On the second, when the parts to be welded are aligned, copper electrodes are pressed against them and the relay is switched, the accumulated energy is discharged.

During the discharge, a large current flows, melting the metal at the point where the electrodes are pressed. As a result, after cooling, the parts are reliably welded.

miniature inverter

Before assembling a small-sized inverter, it is necessary to determine the limiting parameters of the device. If the machine must weld with electrodes up to 4 mm, then the value of the welding current should be 200 A.

The current must be regulated over a wide range. The device must operate from a 220 V household electrical network. After that, you can choose a simple circuit for the device that is closest in terms of parameters.

Most of the components for a mini apparatus can be taken from old electrical appliances, but some elements will have to be purchased at a store.

The composition of the inverter has already been described, it is almost the same for all types, the differences in components and additional functions.

First you need a SH8x8 ferrite core. The primary winding is wound with PEV 0.3 wire. The number of turns is 100. The secondary winding is wound with a copper wire with a cross section of 1 mm2. There are only 14-15 turns here.

The third winding is wound with PEV 0.2 wire in the amount of 15 turns. The fourth and fifth windings are wound with a wire with a cross section of 0.35 mm2, 20 turns each. As a cooling system, you can install a computer fan from an old power supply.

All elements are assembled on one board, transistor switches are installed on radiators. If there is an old housing from an electrical appliance, you can use it.

The front panel displays a light indication in the form of an LED, connectors for a welding cable and a welding current regulator knob. The switch and fuse is usually installed on the back of the appliance.

All typical circuits have been checked, so if assembled correctly, the device should work immediately.

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:

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.
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.
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.
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:

Take the ferrite core.
Perform the first winding (100 turns with a 0.3 mm PEV wire).
The second winding is 15 turns, with a wire with a cross section of 1 mm).
The third winding is 15 turns with a PEV wire of 0.2 mm.
The fourth and fifth - respectively, 20 turns each with wires with a cross section of 0.35 mm.
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.

Quite often, in the practice of any owner, it becomes necessary to connect metal parts. One such connection method is welding. But what if there is no welding machine? Of course, you can buy it, but you can also make the simplest apparatus yourself, and in almost half an hour.

Prologue

The simplest prototype of a welding machine - a lighting electric arc projector - was used in film studios during the filming of films in the middle of the 20th century.

At home, it is possible to make a simple rare home-made welding machine from a 200 W autotransformer. (An approximate diagram of an autotransformer is shown in the figure). The output voltage is regulated by rearranging the TV plug in the sockets.

It is necessary to find two terminals on the secondary winding of the transformer, on which the voltage will be about 40 V. It remains to connect graphite electrodes to these terminals and the welding machine is ready! True, it should be borne in mind that when using such an autotransformer for welding purposes, it is desirable to know the basics of electrical safety well, since galvanic isolation from the mains is not provided.

The scope of such a home-made welding machine is quite wide: from welding metal products to hardening the working surfaces of the tool.

Examples of application of Voltaic arc

In the practice of radio amateurs, at times there is a need for welding or very strong heating of small parts. In such cases, there is no need to use a serious welding machine, because. to create a high-temperature plasma, it is not necessary to have special equipment.

Consider a few examples of the practical application of the Voltaic arc.

Magnetron filament welding with supply rails

In this case, welding is simply necessary, although many, when faced with such a difficulty, replace the magnetron. But most often there are only two malfunctions: the glow breaks at the point (pos. 1) and the feed-through capacitors (pos. 2) fail due to breakdown.

The picture shows a magnetron from a Kenwood microwave oven, which has been in operation for more than twenty years after repair.

Of course, making a thermocouple is a completely hopeless business, but it happens that it needs to be repaired in case of a “ball” breakage. Typically, such thermocouples are found in multimeters that have a temperature measurement mode.

If it is necessary to reshape the spring or make a hole, be aware that a hardened spring is too hard to drill and too brittle to punch a hole with a punch.

And in the case of hardening a steel tool (made of tool steel), it is enough to heat the working surface to a crimson color and cool it in a bath of machine oil. The figure shows a hardened screwdriver tip after machining the working edge.

Minor welding work can be performed using a transformer with a power of 200 watts and an output voltage in the range from 30 to 50 volts. In this case, the welding current should be 10-12 Amperes. You don't have to worry about overheating of the transformer, since the arcing is short-lived.

An ordinary laboratory autotransformer LATR with a current strength of 9 amperes is also suitable. However, it is necessary to take into account the entire degree of danger due to the fact that there is no galvanic isolation from the mains.

In order to prevent damage to the graphite roller of the LATR current collector, it is desirable to introduce limits on the input current using a fusible link (fuse). Then an accidental short circuit in the electrode circuit is no longer scary.

Electrodes can be any graphite rods of simple pencils (preferably soft).

The metal part of the wiring terminal block is used as a holder for the stylus.

This figure shows an example of a holder using a terminal block, where one hole is used to attach the handle, and the second to clamp the stylus in the terminal.

In order to prevent the disposable syringe (pos.3) from melting, when the terminal block (pos.1) is heated, glass-textolite washers (pos.2) are used. And for a standard connection to the cable, you can use a standard socket from the device (pos.4).

So, the connection scheme is quite simple: one output of the secondary winding is connected to the holder, and the second output is connected to the workpiece to be welded.

There is another option for attaching the electrode holder using an electrical terminal. The second holder will be needed in case of welding metal products with the same melting point or, if necessary, to heat up a metal product (hardening, changing shape).

Scheme of connecting two graphite electrodes to the secondary winding of the transformer.

To save the eyes from corneal burns and from sparks, it will not be enough to use dark glasses due to the low density of light filters. You can make such a device: as a shield, there can be a frame of binocular glasses with lenses removed; The filter is attached with a clerical clip. Or you can use amateur radio glasses used in SMD technologies.

In the case of welding copper with nichrome or steel, you will need a flux. When a small amount of water is added to sodium tetraborate (borax) or boric acid, a slurry is obtained, which lubricates the welding points.

Flux preparation materials can usually be found at a hardware store. You can also use the Borax insecticide containing boric acid.

Scheme for connecting an analog CCTV camera to a TV, computer

The principle of operation of the welding machine is to create an integral connection of two or more parts. Such a connection is formed due to the interatomic fusion of the material of the parts being welded. The welding machine acts on the metal with an electric current, which heats it up to the required temperature. Welding can be caused by local action, or by point, general heating of parts, plastic deformation, or a combination of the above effects.

Homemade welder

The welding machine is both technically complex and very simple device. To create it, it is not necessary to have an engineering, and in general, any technical education. All you need is a desire and a little theory, and of course, a willingness to work hard and spend some money.

The cost of creating home-made welding will be much less than buying a ready-made one in a store, but of course, the quality and aesthetic appearance in most cases of store goods will be slightly higher.

In today's article, we will tell you about how to make a mini welding machine with your own hands, write a list of the necessary materials and tools that you will need to collect. We will describe the assembly steps and give some tips that will help you in this matter. After reading the article, you can make a simple homemade welding at home, saving a lot of money.

Required material and tools

The first thing to do in order for the assembly process to proceed as efficiently and quickly as possible is to assemble all the components of the mechanism and the tools that will be required for assembly. To make it easier for you, and to prevent you from collecting or buying unnecessary parts, we have compiled a list of necessary components. So, let's start collecting the parts and tools we need:

To assemble the transformer, we will need core sheets, O-, W- or U-shaped. If these are not available, they can be bought at any electrical store.
Copper or aluminum wire. We recommend using copper, as it is able to conduct higher voltages and withstand temperatures higher than aluminum.
Motor stator, asynchronous.
Insulation for windings such as lacquer or fiberglass.
Electrodes for welding.
Details for radio engineering.
The simplest soldering iron.
Small tools: chisel, files, tweezers with a magnifying glass.
Solder for a soldering iron.

Having prepared all the necessary details, you can begin to assemble the welding machine with your own hands.

Let's analyze the scheme we need

The simplest mini welding machine circuit is that the incoming current goes to the welding transformer. Further, with the help of stabilizing and rectifying structural elements, the welding current becomes controlled and suitable for work.

Transformer Block Diagram

Of course, the device can only consist of a transformer, but then the arc will be less stable and efficient, although in capable hands it will work quite well and perform the assigned tasks.

Various schemes of welders

The arc power supply has the following current flow sequence:

The voltage is supplied to the welding transformer.
Then it hits the throttle, the resistance coil.
In the coil, the current lends itself to active resistance, after which it enters the diode bridge.
Then it passes through the current regulator, with which the required arc welding force is set.
The welding process begins when the electrode touches the workpiece.

Stages of the assembly process of mini welding

Having collected all the necessary elements and familiarized yourself with our scheme, you can proceed to the phased assembly of the device. The work is simple, but very painstaking and monotonous. Get ready to spend many hours in the same sitting and doing the same hand movements.

Round-shaped transformers have become the most popular, but their self-assembly is somewhat more difficult, so we will use a U-shaped core in our circuit. This form of transformer is the leader among home-made samples, due to its simplicity.

Let's proceed to the description of the assembly steps:

The first thing we need to do is the base for the windings. You can use plastic platinum, wooden, in general, everything that is a dielectric. Textolite plates are very suitable. Having dealt with the material, we proceed to create the form. It will consist of two covers, upper and lower and central partitions. Holes are made in each cover, the diameter is selected based on the size of the plates that will be installed inside.
It is necessary to insulate each part with heat-resistant electrical tape, in 1-2 layers. Then we collect and begin to lay the winding. The copper wire used is best taken immediately in glass insulation that can withstand elevated temperatures. Thus, you will protect yourself from overheating of the device, but it will cost a little more than using a conventional winding. Each layer of the winding must be carefully insulated without gaps, and only then proceed to the next ball. Based on how much power you need, make taps at the right winding levels. Having finished the last ball, we isolate it in 2-3 layers, for greater security.
The next step is to assemble the magnetic circuit for the welding transformer. We use material specially designed for this type of device. It has the necessary inductive properties, which are selected specifically for welding machines. Having collected all the platinums in a single structure, it is necessary to check each winding with a tester for errors and other things.
We assemble the diode bridge and connect it to our device. Take diodes from the B200 or KVRS5010 series. Each such diode can withstand 50A and this figure is summed up. Therefore, for a home-made device with a power of 220A, it is necessary to install 5 such diodes.
Diodes require a heatsink to dissipate heat. Connect the diodes together with the inductor.
To improve the cooling system, you can install a cooler in the case that will draw hot air out of the case.

The inverter apparatus is made according to the same type, only instead of a transformer, it is necessary to install a high-frequency welding transformer. The current will not be supplied directly to the transformer, but through a conversion module that will convert alternating current into direct current with an increase in its frequency.

You should also add circuit breakers that will protect the device from excessive power surges. Such a device will have a significantly smaller size and weight due to the lightweight structure of the transformer used.

Is the device worth your time and money?

From the point of view of performance, home-made welding will be no worse than store-bought. The only thing that you most likely will not be able to install is additional systems such as anti-sticking or quick start. But with due skill, they can be added. In all other respects, they will be able to perform absolutely similar functions.

The price of a homemade device can be completely different, it all depends on whether you buy all the parts or assemble from what you have in your garage. In the case of the purchase of all components, the price will be approximately 8-10 times less than that of store models. In this case, you will need to spend 1-2 days to assemble the entire structure.

Summarize

Making a homemade welding machine at home is quite easy, just familiarize yourself with the theory and have a few free days left. The process is rather dreary and monotonous, most of the work is cyclical hand movements. But the time spent is worth it, because you save a significant amount, while getting a device no worse than in a store.

No work with iron can do without a welding machine. It allows you to cut and connect metal parts of any size and thickness. A good solution is to do your own welding, because good models are expensive, and cheap ones are of poor quality. To implement the idea of \u200b\u200bself-manufacturing a welder, it is necessary to acquire special equipment that allows you to hone the quality skills of a specialist in real conditions.

Types and characteristics of the tool

After all the necessary conditions for the preparatory stage are successfully met, it becomes possible to make a model of the welding device with your own hands. Today there are many schematic diagrams by which the device can be manufactured. They operate in one of the following ways:

Direct or alternating current.
Pulse or inverter.
Automatic or semi-automatic.

It is worth paying attention to the apparatus belonging to the transformer type. An important characteristic of this device is its operation on alternating current, which allows it to be used in domestic conditions. AC devices are capable of providing the nomenclature quality of welded joints. A unit of this type can easily find its application in everyday life. when servicing real estate located in the private sector.

In order to assemble such a device, you must have:

About 20 meters of cable or wire of large cross section.
High magnetic permeability metal base to be used as the core of the transformer.

The optimal core configuration has a U-shaped rod base. In theory, a core of any other configuration can easily fit, for example, a round shape taken from a stator that has become unusable. But in practice, winding the winding on such a base is much more difficult.

The cross-sectional area for a core belonging to a home-made household welding machine is 50 cm 2. This will be enough to use rods from 3 to 4 mm in diameter in the installation. The use of a larger section will only lead to an increase in the mass of the structure, and the efficiency of the apparatus will not become higher.

Manufacturing instructions

For the primary winding, it is necessary to use a copper wire with high heat resistance, since during welding it will be exposed to high temperatures. The wire used must be selected according to fiberglass or cotton insulation designed for stationary use in the high temperature zone.

For the winding of the transformer, it is not allowed to use a wire with PVC insulation, which, when heated, will instantly become unusable. In some cases, insulation for the transformer winding is made independently.

To perform this procedure, you need to take a blank made of cotton fabric or fiberglass, cut it into strips about 2 cm wide, wrap the prepared wire with them and soak the bandage with any varnish that has electrical properties. Such insulation in terms of thermal characteristics will not yield to any factory analogue.

Coils are wound according to a certain principle. First, half of the primary winding is wound, followed by half of the secondary. Then proceed to the second coil using the same technique. To improve the quality of the insulating coating, fragments of strips of cardboard, fiberglass or pressed paper are inserted between the layers of the windings.

Hardware setup

Next, you need to configure. It is produced by turning on the equipment in the network and taking voltage readings from the secondary winding. The voltage on it should be from 60 to 65 volts.

Precise adjustment of the parameters is carried out by reducing or increasing the length of the winding. To obtain a qualitative result, the voltage on the secondary winding should be adjusted to the specified parameters.

A VRP cable or a SHRPS wire is connected to the primary winding of the finished welding transformer, which will be used to connect to the network. One of the outputs of the secondary winding is fed to the terminal, to which the “mass” will subsequently be connected, and the second is fed to the terminal connected to the cable. The last procedure is completed and the new welding machine is ready for operation.

Small unit production

For the manufacture of a small welding machine, an autotransformer from a Soviet-style TV is easily suitable. It can be easily used to obtain a voltaic arc. In order for everything to work out correctly, graphite electrodes are connected between the terminals of the autotransformer. This simple design allows you to perform several simple tasks using welding, such as:

Making or repairing thermocouples.
Heating up to the maximum temperature of high-carbon steel products.
Hardening of tool steel.

A home-made welding machine, created on the basis of an autotransformer, has a significant drawback. It must be used with extra precautions. Without galvanic isolation from the electrical network, it is a rather dangerous device.

The optimal parameters of an autotransformer suitable for creating a welding machine are considered to be an output voltage in the range from 40 to 50 volts and low power from 200 to 300 watts. This device is capable of delivering from 10 to 12 amperes of operating current, which will be sufficient when welding wires, thermocouples and other elements.

As electrodes for a do-it-yourself mini welding machine, you can use leads from a simple pencil. Holders for improvised electrodes can serve as terminals that are on various electrical appliances.

For welding, the holder is connected to one of the terminals of the secondary winding, and the workpiece to be welded to the other. The handle for the holder is best made from fiberglass washer or other heat-resistant material. It should be noted that the arc of such a device operates for a rather short time, preventing the autotransformer used from overheating.

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