Contact welding - how to make equipment and pliers yourself? Homemade welding machines Portable welding machine based on "Latra"

1.1. General information.

Depending on the type of current used for welding, there are DC and AC welding machines. Welding machines using low direct currents are used for welding sheet metal, in particular, roofing and automotive steel. The welding arc in this case is more stable and, at the same time, welding can occur both on direct and reverse polarity of the supplied DC voltage.

At direct current, you can cook with electrode wire without coating and electrodes that are designed for welding metals at direct or alternating current. To give the arc burning at low currents, it is desirable to have an increased open-circuit voltage U xx up to 70 ...

Fig.1 Schematic diagram of the bridge rectifier of the welding machine, indicating the polarity when welding thin sheet metal

To smooth out voltage ripples, one of the CA leads is connected to the electrode holder through a T-shaped filter, consisting of a choke L1 and a capacitor C1. Inductor L1 is a coil of 50 ... 70 turns of a copper bus with a tap from the middle with a cross section of S = 50 mm 2 wound on a core, for example, from an OSO-12 step-down transformer, or more powerful. The larger the iron section of the smoothing inductor, the less likely it is that its magnetic system will enter saturation. When the magnetic system enters saturation at high currents (for example, when cutting), the inductance of the inductor decreases abruptly and, accordingly, current smoothing will not occur. The arc will then burn unsteadily. Capacitor C1 is a battery of capacitors such as MBM, MBG or the like with a capacity of 350-400 microfarads for a voltage of at least 200 V

Characteristics of powerful diodes and their imported counterparts can be. Or by clicking on the link you can download a guide to diodes from the series "Helping a radio amateur No. 110"

For rectification and smooth regulation of the welding current, circuits based on powerful controlled thyristors are used, which allow you to change the voltage from 0.1 xx to 0.9U xx. In addition to welding, these regulators can be used to charge batteries, power electric heating elements and other purposes.

In AC welding machines, electrodes with a diameter of more than 2 mm are used, which makes it possible to weld products with a thickness of more than 1.5 mm. During welding, the current reaches tens of amperes and the arc burns quite steadily. In such welding machines, special electrodes are used, which are intended only for welding on alternating current.

For the normal operation of the welding machine, a number of conditions must be met. The output voltage must be sufficient for reliable ignition of the arc. For an amateur welding machine U xx \u003d 60 ... 65V. For the safety of work, a higher no-load output voltage is not recommended; for industrial welding machines, for comparison, U xx can be 70..75 V..

Welding voltage value I St. must ensure stable arc burning, depending on the diameter of the electrode. The value of the welding voltage U sv can be 18 ... 24 V.

The rated welding current must be:

I St \u003d KK 1 * d e, where

I St- the value of the welding current, A;

K1 =30...40- coefficient depending on the type and size of the electrode d e, mm.

The short circuit current must not exceed the rated welding current by more than 30...35%.

It has been noted that stable arcing is possible if the welding machine has a falling external characteristic, which determines the relationship between current and voltage in the welding circuit. (fig.2)

Fig.2 Falling external characteristic of the welding machine:

At home, as practice shows, it is quite difficult to assemble a universal welding machine for currents of 15 ... 20 to 150 ... 180 A. In this regard, when designing a welding machine, one should not strive to completely cover the range of welding currents. It is advisable at the first stage to assemble a welding machine for working with electrodes with a diameter of 2 ... 4 mm, and at the second stage, if it is necessary to work at low welding currents, supplement it with a separate rectifier device with smooth regulation of the welding current.

An analysis of the designs of amateur welding machines at home allows us to formulate a number of requirements that must be met in their manufacture:

Small dimensions and weight
Mains supply 220 V
The duration of work should be at least 5 ... 7 electrodes d e \u003d 3 ... 4 mm

The weight and dimensions of the device directly depend on the power of the device and can be reduced by reducing its power. The duration of the welding machine depends on the material of the core and the heat resistance of the insulation of the winding wires. To increase the welding time, it is necessary to use steel with high magnetic permeability for the core.

1. 2. Choice of core type.

For the manufacture of welding machines, mainly rod-type magnetic cores are used, since they are more technologically advanced in design. The core of the welding machine can be assembled from plates of electrical steel of any configuration with a thickness of 0.35 ... 0.55 mm and pulled together with pins isolated from the core (Fig. 3).

Fig.3 Rod-type magnetic core:

When selecting the core, it is necessary to take into account the dimensions of the "window" in order to fit the windings of the welding machine, and the area of \u200b\u200bthe transverse core (yoke) S=a*b, cm 2 .

As practice shows, the minimum values S=25..35 cm 2 should not be chosen, since the welding machine will not have the required power reserve and it will be difficult to obtain high-quality welding. And hence, as a consequence, the possibility of overheating of the device after a short operation. To avoid this, the cross section of the core of the welding machine should be S = 45..55 cm 2. Although the welding machine will be somewhat heavier, it will work reliably!

It should be noted that amateur welding machines on toroidal type cores have electrical characteristics 4 ... 5 times higher than those of a rod type, and hence small electrical losses. It is more difficult to manufacture a welding machine using a toroidal type core than with a rod type core. This is mainly due to the placement of the windings on the torus and the complexity of the winding itself. However, with the right approach, they give good results. The cores are made from strip transformer iron rolled into a roll in the shape of a torus.

Rice. 4 Toroidal type magnetic core:

To increase the inner diameter of the torus ("window"), a part of the steel tape is unwound from the inside and wound on the outer side of the core (Fig. 4). After rewinding the torus, the effective cross section of the magnetic circuit will decrease, therefore, it will be necessary to partially wind the torus with iron from another autotransformer until the cross section S is at least 55 cm 2.

The electromagnetic parameters of such iron are most often unknown, so they can be determined experimentally with sufficient accuracy.

1. 3. Choice of winding wire.

For the primary (network) windings of the welding machine, it is better to use a special heat-resistant copper winding wire in cotton or fiberglass insulation. Satisfactory heat resistance is also possessed by wires in rubber or rubber-fabric insulation. It is not recommended to use wires in polyvinyl chloride (PVC) insulation for operation at elevated temperatures due to its possible melting, leakage from the windings and short circuit of the turns. Therefore, PVC insulation from the wires must either be removed and wrapped around the wires along the entire length with cotton insulating tape, or not removed at all, but wrapped over the wire over the insulation.

When selecting the section of the winding wires, taking into account the periodic operation of the welding machine, a current density of 5 A/mm2 is allowed. The power of the secondary winding can be calculated by the formula P 2 \u003d I sv * U sv. If welding is carried out with an electrode de = 4 mm, at a current of 130 ... 160 A, then the power of the secondary winding will be: P 2 \u003d 160 * 24 \u003d 3.5 ... 4 kW, and the power of the primary winding, taking into account losses, will be about 5...5.5 kW. Based on this, the maximum current in the primary winding can reach 25 A. Therefore, the cross-sectional area of the wire of the primary winding S 1 must be at least 5..6 mm 2.

In practice, it is desirable to take a slightly larger cross-sectional area of \u200b\u200bthe wire, 6 ... 7 mm 2. For winding, a rectangular bus or a copper winding wire with a diameter of 2.6 ... 3 mm is taken, excluding insulation. The cross-sectional area S of the winding wire in mm2 is calculated by the formula: S \u003d (3.14 * D 2) / 4 or S \u003d 3.14 * R 2; D is the bare copper wire diameter, measured in mm. In the absence of a wire of the required diameter, the winding can be carried out in two wires of a suitable section. When using aluminum wire, its cross section must be increased by 1.6..1.7 times.

The number of turns of the primary winding W1 is determined from the formula:

W 1 \u003d (k 2 * S) / U 1, where

k 2 - constant coefficient;

S- cross-sectional area of \u200b\u200bthe yoke in cm 2

You can simplify the calculation by using a special program for the calculation Welding Calculator

With W1 = 240 turns, taps are made from 165, 190 and 215 turns, i.e. every 25 turns. More taps of the network winding, as practice shows, is not practical.

This is due to the fact that by reducing the number of turns of the primary winding, both the power of the welding machine and U xx increase, which leads to an increase in the arcing voltage and a deterioration in the quality of welding. By changing only the number of turns of the primary winding, it is not possible to achieve overlapping of the range of welding currents without deteriorating the quality of welding. In this case, it is necessary to provide for switching turns of the secondary (welding) winding W 2 .

The secondary winding W 2 must contain 65 ... 70 turns of an insulated copper bus with a cross section of at least 25 mm2 (preferably a cross section of 35 mm2). A flexible stranded wire, such as a welding wire, and a three-phase power stranded cable are also suitable for winding the secondary winding. The main thing is that the cross section of the power winding is not less than required, and the wire insulation is heat-resistant and reliable. If the wire section is insufficient, winding in two or even three wires is possible. When using aluminum wire, its cross section must be increased by 1.6 ... 1.7 times. The welding winding leads are usually led through copper lugs under terminal bolts with a diameter of 8 ... 10 mm (Fig. 5).

1.4. Features of winding windings.

There are the following rules for winding the windings of the welding machine:

Winding must be carried out on an insulated yoke and always in the same direction (for example, clockwise).
Each winding layer is insulated with a layer of cotton insulation (fiberglass, electric cardboard, tracing paper), preferably impregnated with bakelite varnish.
The winding leads are tinned, marked, fixed with cotton tape, and cotton cambric is additionally put on the network winding leads.
With poor-quality wire insulation, winding can be done in two wires, one of which is a cotton cord or cotton thread for fishing. After winding one layer, the winding with cotton thread is fixed with glue (or varnish) and only after it has dried, the next row is wound.

The network winding on a rod-type magnetic circuit can be arranged in two main ways. The first method allows you to get a more "hard" welding mode. The network winding in this case consists of two identical windings W1, W2, located on different sides of the core, connected in series and having the same wire cross section. To adjust the output current, taps are made on each of the windings, which are closed in pairs ( Rice. 6 a, b)

Rice. 6. Ways of winding CA windings on a core of a rod type:

The second method of winding the primary (network) winding is winding the wire on one side of the core ( rice. 6 c, d). In this case, the welding machine has a steeply falling characteristic, welds "softly", the arc length has less effect on the magnitude of the welding current, and therefore on the quality of welding.

After winding the primary winding of the welding machine, it is necessary to check for the presence of short-circuited turns and the correctness of the selected number of turns. The welding transformer is connected to the network through a fuse (4 ... 6 A) and if there is an alternating current ammeter. If the fuse burns out or gets very hot, this is a clear sign of a shorted coil. In this case, the primary winding must be rewound, paying special attention to the quality of the insulation.

If the welding machine is very buzzing, and the current consumption exceeds 2 ... 3 A, then this means that the number of turns of the primary winding is underestimated and it is necessary to rewind a certain number of turns. A working welding machine should consume no more than 1..1.5 A at idle, not get warm and not hum strongly.

The secondary winding of the welding machine is always wound on two sides of the core. According to the first method of winding, the secondary winding consists of two identical halves, connected in anti-parallel to increase the stability of the arc (Fig. 6 b). In this case, the wire cross section can be taken somewhat less, that is, 15..20 mm 2. When winding the secondary winding according to the second method, at first 60 ... 65% of the total number of its turns is wound on the side of the core free from windings.

This winding is used mainly to start the arc, and during welding, due to a sharp increase in the dispersion of the magnetic flux, the voltage across it drops by 80 ... 90%. The remaining number of turns of the secondary winding in the form of an additional welding winding W 2 is wound over the primary. Being power, it maintains the welding voltage within the required limits, and, consequently, the welding current. The voltage on it drops in the welding mode by 20 ... 25% relative to the open circuit voltage.

The winding of the windings of the welding machine on a toroidal type core can also be done in several ways ( Rice. 7).

Ways of winding the windings of the welding machine on a toroidal core.

Switching windings in welding machines is easier to do with copper lugs and terminals. Copper tips at home can be made from copper tubes of a suitable diameter 25 ... 30 mm long, fixing the wires in them by crimping or soldering. When welding in various conditions (strong or low-current network, long or short supply cable, its cross section, etc.), by switching the windings, the welding machine is set to the optimal welding mode, and then the switch can be set to the neutral position.

1.5. Setting up the welding machine.

Having made a welding machine, a home electrician must set it up and check the quality of welding with electrodes of various diameters. The setup process is as follows. To measure the welding current and voltage, you need: an AC voltmeter for 70 ... 80 V and an AC ammeter for 180 ... 200 A. The connection diagram of the measuring instruments is shown in ( Rice. eight)

Rice. eight Schematic diagram of connecting measuring instruments when setting up a welding machine

When welding with different electrodes, the values of the welding current - I sv and the welding voltage U sv are taken, which should be within the required limits. If the welding current is small, which happens most often (the electrode sticks, the arc is unstable), then in this case, by switching the primary and secondary windings, the required values \u200b\u200bare set, or the number of turns of the secondary winding is redistributed (without increasing them) in the direction of increasing the number of turns wound over the network windings.

After welding, it is necessary to control the quality of welding: the depth of penetration and the thickness of the deposited metal layer. For this purpose, the edges of the products to be welded are broken or sawn. According to the measurement results, it is desirable to compile a table. Analyzing the data obtained, the optimal welding modes are selected for electrodes of various diameters, bearing in mind that when welding with electrodes, for example, with a diameter of 3 mm, electrodes with a diameter of 2 mm can be cut, because cutting current is 30...25% more than welding current.

The connection of the welding machine to the network should be made with a wire with a cross section of 6 ... 7 mm through an automatic machine for a current of 25 ... 50 A, for example, AP-50.

The electrode diameter, depending on the thickness of the metal to be welded, can be selected based on the following relationship: de=(1...1.5)*V, where B is the thickness of the metal to be welded, mm. The length of the arc is selected depending on the diameter of the electrode and is on average equal to (0.5...1.1)de. It is recommended to perform welding with a short arc of 2...3 mm, the voltage of which is 18...24 V. An increase in the length of the arc leads to a violation of the stability of its combustion, an increase in waste losses and spatter, and a decrease in the depth of penetration of the base metal. The longer the arc, the higher the welding voltage. The welding speed is chosen by the welder depending on the grade and thickness of the metal.

When welding in direct polarity, the plus (anode) is connected to the workpiece and the minus (cathode) to the electrode. If it is necessary that less heat is generated on the parts, for example, when welding thin-sheet structures, then reverse polarity welding is used. In this case, the minus (cathode) is attached to the workpiece to be welded, and the plus (anode) is attached to the electrode. This not only ensures less heating of the welded part, but also accelerates the process of melting the electrode metal due to the higher temperature of the anode zone and the greater heat supply.

Welding wires are connected to the welding machine through copper lugs under the terminal bolts on the outside of the body of the welding machine. Bad contact connections reduce the power characteristics of the welding machine, worsen the quality of welding and can cause them to overheat and even ignite the wires.

With a short length of welding wires (4..6 m), their cross-sectional area must be at least 25 mm 2.

During welding, fire safety rules must be observed, and when setting up the device and electrical safety - during measurements with electrical appliances. Welding must be carried out in a special mask with protective glass grade C5 (for currents up to 150 ... 160 A) and gloves. All switching in the welding machine must be done only after disconnecting the welding machine from the mains.

2. Portable welding machine based on "Latra".

2.1. Design feature.

The welding machine is powered by a 220 V AC mains. Rice. nine).

For the magnetic circuit of the transformer, tape transformer iron is used, rolled into a roll in the shape of a torus. As you know, in traditional designs of transformers, the magnetic circuit is recruited from W-shaped plates. The electrical characteristics of the welding machine, due to the use of a torus-shaped transformer core, are 5 times higher than those of machines with W-shaped plates, and the losses are minimal.

2.2. Improvements "Latra".

For the transformer core, you can use ready-made "LATR" type M2.

Note. All latras have a six-pin block and voltage: at the input 0-127-220, and at the output 0-150 - 250. There are two types: large and small, and are called LATR 1M and 2M. Which one I don't remember. But, for welding, it is precisely a large LATR with rewound iron that is needed, or, if they are serviceable, then the secondary windings are wound with a bus and after that the primary windings are connected in parallel, and the secondary windings are connected in series. In this case, it is necessary to take into account the coincidence of the directions of currents in the secondary winding. Then it turns out something similar to a welding machine, although it cooks, like all toroidal ones, a little harsh.

You can use a magnetic circuit in the form of a torus from a burned-out laboratory transformer. In the latter case, the fence and fittings are first removed from the Latra and the burnt winding is removed. If necessary, the cleaned magnetic circuit is rewound (see above), insulated with electric cardboard or two layers of varnished cloth, and the transformer windings are wound. The welding transformer has only two windings. For winding the primary winding, a piece of PEV-2 wire 170 m long and 1.2 mm in diameter is used ( Rice. ten)

Rice. ten Winding of the windings of the welding machine:

1 - primary winding;	3 - wire coil;
2 - secondary winding;	4 - yoke

For the convenience of winding, the wire is pre-wound on a shuttle in the form of a wooden lath 50x50 mm with slots. However, for greater convenience, you can make a simple device for winding toroidal power transformers

Having wound the primary winding, it is covered with a layer of insulation, and then the secondary winding of the transformer is wound. The secondary winding contains 45 turns and is wound with copper wire in cotton or vitreous insulation. Inside the core, the wire is coil to coil, and outside - with a small gap, which is necessary for better cooling. A welding machine manufactured according to the above method is capable of delivering a current of 80 ... 185 A. The circuit diagram of the welding machine is shown on rice. eleven.

Rice. eleven Schematic diagram of the welding machine.

The work will be somewhat simplified if it is possible to purchase a working "Latr" for 9 A. Then they remove the fence, the current-collecting slider and the mounting fittings from it. Next, the terminals of the primary winding for 220 V are determined and marked, and the remaining terminals are securely isolated and temporarily pressed against the magnetic circuit so that they are not damaged when winding a new (secondary) winding. The new winding contains the same number of turns of the same brand and the same wire diameter as in the variant considered above. The transformer in this case gives a current of 70 ... 150 A.
The manufactured transformer is placed on an insulated platform in the old casing, having previously drilled ventilation holes in it (Fig. 12))

Rice. 12 Variants of the casing of the welding machine based on "LATRA".

The outputs of the primary winding are connected to the 220 V network with a SHRPS or VRP cable, while an AP-25 disconnecting machine should be installed in this circuit. Each output of the secondary winding is connected to a flexible insulated wire PRG. The free end of one of these wires is attached to the electrode holder, and the free end of the other is attached to the workpiece. The same end of the wire must be grounded for the safety of the welder. The adjustment of the current of the welding machine is carried out by connecting in series to the wire circuit of the electrode holder pieces of nichrome or constantan wire d = 3 mm and 5 m long, rolled up with a “snake”. "Snake" is attached to a sheet of asbestos. All connections of wires and ballast are made with M10 bolts. Moving along the "snake" the point of attachment of the wire, set the required current. The current can be adjusted using electrodes of various diameters. For welding with such a device, electrodes of the type E-5RAUONII-13 / 55-2.0-UD1 dd \u003d 1 ... 3 mm are used.

When carrying out welding work, to prevent burns, it is necessary to use a fiber protective shield equipped with a light filter E-1, E-2. Headgear, overalls and gloves are obligatory. The welding machine should be protected from moisture and not allowed to overheat. Approximate modes of operation with an electrode d = 3 mm: for transformers with a current of 80 ... 185 A - 10 electrodes, and with a current of 70 ... 150 A - 3 electrodes. after using the specified number of electrodes, the device is disconnected from the mains for at least 5 minutes (and preferably about 20).

3. Welding machine from a three-phase transformer.

The welding machine, in the absence of "LATRA", can also be made on the basis of a three-phase step-down transformer 380/36 V, with a power of 1..2 kW, which is designed to power low-voltage power tools or lighting (Fig. 13).

Rice. thirteen General view of the welding machine and its core.

Even an instance with one blown winding is suitable here. Such a welding machine operates from an alternating current network with a voltage of 220 V or 380 V and with electrodes up to 4 mm in diameter allows welding metal with a thickness of 1 ... 20 mm.

3.1. Details.

Terminals for the conclusions of the secondary winding can be made from a copper tube d 10 ... 12 mm and a length of 30 ... 40 mm (Fig. 14).

Rice. fourteen The design of the terminal of the secondary winding of the welding machine.

On the one hand, it should be riveted and a hole d 10 mm drilled in the resulting plate. Carefully stripped wires are inserted into the terminal tube and crimped with light hammer blows. To improve contact on the surface of the terminal tube, notches can be made with a core. On the panel located at the top of the transformer, the standard screws with M6 nuts are replaced with two screws with M10 nuts. It is desirable to use copper screws and nuts for new screws and nuts. They are connected to the terminals of the secondary winding.

For the conclusions of the primary winding, an additional board is made of sheet textolite 3 mm thick ( fig.15).

Rice. fifteen General view of the scarf for the conclusions of the primary winding of the welding machine.

10 ... 11 holes d = 6mm are drilled in the board and M6 screws with two nuts and washers are inserted into them. After that, the board is attached to the top of the transformer.

Rice. sixteen Schematic diagram of the connection of the primary windings of the transformer for voltage: a) 220 V; b) 380 V (secondary winding not specified)

When the apparatus is powered from a 220 V network, its two extreme primary windings are connected in parallel, and the middle winding is connected to them in series ( fig.16).

4. Electrode holder.

4.1. Holder for electrodes made of d¾" pipe.

The simplest is the design of the electric holder, made of a pipe d¾ "and 250 mm long ( fig.17).

On both sides of the pipe at a distance of 40 and 30 mm from its ends, cuts are cut with a hacksaw to a depth of half the diameter of the pipe ( fig.18)

Rice. eighteen Drawing of the body of the holder of the electrodes from the pipe d¾"

A piece of steel wire d = 6 mm is welded to the pipe above a large recess. On the opposite side of the holder, a hole d = 8.2 mm is drilled, into which an M8 screw is inserted. A terminal is attached to the screw from the cable going to the welding machine, which is clamped with a nut. A piece of rubber or nylon hose with a suitable inner diameter is put on top of the pipe.

4.2. The holder of electrodes from steel corners.

A convenient and easy-to-design electrode holder can be made from two steel corners 25x25x4 mm ( rice. nineteen)

They take two such corners about 270 mm long and connect them with small corners and bolts with M4 nuts. The result is a box with a section of 25x29 mm. In the resulting case, a window for the latch is cut out and a hole is drilled for installing the axis of the latch and electrodes. The latch consists of a lever and a small key made of 4 mm thick steel sheet. This part can also be made from a corner of 25x25x4 mm. To ensure reliable contact of the latch with the electrode, a spring is put on the latch axis, and the lever is connected to the body with a contact wire.

The handle of the resulting holder is covered with an insulating material, which is used as a piece of rubber hose. The electric cable from the welding machine is connected to the housing terminal and fixed with a bolt.

5. Electronic current regulator for welding transformer.

An important design feature of any welding machine is the ability to adjust the operating current. there are such ways of adjusting the current in welding transformers: shunting with the help of various types of chokes, changing the magnetic flux due to the mobility of the windings or magnetic shunting, the use of stores of active ballast resistances and rheostats. All of these methods have both their advantages and disadvantages. For example, the disadvantage of the latter method is the complexity of the design, the bulkiness of the resistances, their strong heating during operation, and inconvenience when switching.

The most optimal method is the stepwise adjustment of the current, by changing the number of turns, for example, by connecting to the taps made when winding the secondary winding of the transformer. However, this method does not allow wide adjustment of the current, so it is usually used to adjust the current. Among other things, adjusting the current in the secondary circuit of the welding transformer is associated with certain problems. In this case, significant currents pass through the control device, which is the reason for the increase in its dimensions. For the secondary circuit, it is practically impossible to find powerful standard switches that would withstand currents up to 260 A.

If we compare the currents in the primary and secondary windings, it turns out that the current in the circuit of the primary winding is five times less than in the secondary winding. This suggests the idea of placing the welding current regulator in the primary winding of the transformer, using thyristors for this purpose. On fig. 20 shows a diagram of the thyristor welding current controller. With the utmost simplicity and availability of the element base, this regulator is easy to manage and does not require configuration.

Power regulation occurs when the primary winding of the welding transformer is periodically switched off for a fixed period of time at each half-cycle of current. In this case, the average value of the current decreases. The main elements of the regulator (thyristors) are connected opposite and parallel to each other. They are alternately opened by current pulses generated by transistors VT1, VT2.

When the regulator is connected to the network, both thyristors are closed, capacitors C1 and C2 begin to charge through the variable resistor R7. As soon as the voltage on one of the capacitors reaches the avalanche breakdown voltage of the transistor, the latter opens, and the discharge current of the capacitor connected to it flows through it. Following the transistor, the corresponding thyristor opens, which connects the load to the network.

By changing the resistance of the resistor R7, you can control the moment the thyristors are turned on from the beginning to the end of the half-cycle, which in turn leads to a change in the total current in the primary winding of the welding transformer T1. To increase or decrease the adjustment range, you can change the resistance of the variable resistor R7 up or down, respectively.

Transistors VT1, VT2, operating in avalanche mode, and resistors R5, R6 included in their base circuits, can be replaced with dinistors (Fig. 21)

Rice. 21 Schematic diagram of replacing a transistor with a resistor with a dinistor, in the current regulator circuit of a welding transformer.

the anodes of the dinistors should be connected to the extreme terminals of the resistor R7, and the cathodes should be connected to the resistors R3 and R4. If the regulator is assembled on dinistors, then it is better to use devices such as KN102A.

As VT1, VT2, old-style transistors such as P416, GT308 have proven themselves well, however, these transistors, if desired, can be replaced with modern low-power high-frequency transistors with similar parameters. Variable resistor type SP-2, and fixed resistors type MLT. Capacitors of the MBM or K73-17 type for an operating voltage of at least 400 V.

All parts of the device are assembled on a textolite plate with a thickness of 1 ... 1.5 mm using surface mounting. The device has a galvanic connection with the network, so all elements, including thyristor heat sinks, must be isolated from the case.

A properly assembled welding current regulator does not require special adjustment, you just need to make sure that the transistors are stable in avalanche mode or, when using dinistors, that they are turned on.

A description of other designs can be found on the site http://irls.narod.ru/sv.htm, but I want to warn you right away that many of them have at least controversial points.

Also on this topic you can see:

http://valvolodin.narod.ru/index.html - many GOSTs, diagrams of both home-made devices and factory ones

http://www.y-u-r.narod.ru/Svark/svark.htm the same website of a welding enthusiast

When writing the article, some of the materials from the book by Pestrikov V. M. "Home electrician and not only ..." were used.

The homemade welding machine from LATR 2 It is built on the basis of a nine-ampere LATR 2 (laboratory adjustable autotransformer) and its design provides for welding current adjustment. The presence of a diode bridge in the design of the welding machine allows welding with direct current.

Current regulator circuit for a welding machine

The operating mode of the welding machine is controlled by a variable resistor R5. Thyristors VS1 and VS2 open each in their own half-cycle alternately for a certain period of time due to the phase-shifting circuit built on the elements R5, C1 and C2.

As a result, it becomes possible to change the input voltage on the primary winding of the transformer from 20 to 215 volts. As a result of the transformation, a reduced voltage appears on the secondary winding, which makes it easy to ignite the welding arc at terminals X1 and X2 when welding with alternating current and at terminals X3 and X4 when welding with direct current.

The welding machine is connected to the mains with an ordinary plug. In the role of the switch SA1, you can use a paired machine for 25A.

Material: ABS + metal + acrylic lenses. Neon lights...

Alteration of LATR 2 for a homemade welding machine

First, the protective cover, electrically removable contact and mount are removed from the autotransformer. Next, a good electrical insulation is wound on the existing 250 volt winding, for example, fiberglass, on top of which 70 turns of the secondary winding are laid. For the secondary winding, it is desirable to choose a copper wire with a cross-sectional area of \u200b\u200babout 20 square meters. mm.

If there is no wire of a suitable cross section, it is possible to make a winding of several wires with a total cross-sectional area of 20 sq. mm. The modified LATR2 is mounted in a suitable home-made case with ventilation holes. It is also necessary to install the regulator board, a package switch, as well as terminals for X1, X2 and X3, X4.

In the absence of LATR 2, the transformer can be made home-made by winding the primary and secondary windings on a core of transformer steel. The cross section of the core should be approximately 50 square meters. see. The primary winding is wound with a PEV2 wire with a diameter of 1.5 mm and contains 250 turns, the secondary is the same which is wound on LATR 2.

At the output of the secondary winding, a diode bridge of powerful rectifier diodes is connected. Instead of the diodes indicated in the diagram, you can use D122-32-1 diodes or 4 VL200 diodes (electric locomotive). Diodes for cooling must be installed on homemade radiators with an area of at least 30 square meters. cm.

Another essential point is the choice of cable for the welding machine. For this welder, it is necessary to use a copper multi-core cable in rubber insulation with a cross section of at least 20 sq. mm. You need two pieces of cable 2 meters long. Each must be well crimped with terminal lugs for connection to the welding machine.

From a compact and at the same time quite reliable, cheap and easy-to-manufacture “welder”, not a single artisan, homely owner will refuse. Especially if he finds out that this apparatus is based on an easily upgradeable 9-ampere (familiar to almost everyone from school physics lessons) laboratory autotransformer LATR2 and a self-made thyristor mini-regulator with a rectifier bridge. They allow not only to safely connect to a 220V AC household lighting network, but also to change Uw on the electrode, which means choosing the desired welding current value. Operating modes are set using a potentiometer. Together with capacitors C2 and C3, it forms phase-shifting chains, each of which, triggering during its half-cycle, opens the corresponding thyristor for a certain period of time. As a result, adjustable 20-215 V are on the primary winding of the welding T1. Transforming in the secondary winding, the required -Us make it easy to ignite the arc for welding on alternating (terminals X2, X3) or rectified (X4, X5) current. Fig.1.

Homemade welding machine based on LATR. Welding transformer based on the widely used LATR2 (a), its connection to the circuit diagram of a self-made adjustable apparatus for welding on alternating or direct current (b) and a voltage diagram explaining the operation of the transistor electric arc burning mode controller. Resistors R2 and R3 shunt the control circuits of thyristors VS1 and VS2. Capacitors C1, C2 reduce to an acceptable level of radio interference that accompanies the arc discharge. In the role of the light indicator HL1, signaling the inclusion of the device in the household electrical network, a neon lamp with a current-limiting resistor R1 is used.

To connect the "welder" to the apartment wiring, a conventional plug X1 is applicable. But it is better to use a more powerful electrical connector, which is commonly called a "Euro plug-Euro socket". And as the SB1 switch, the VP25 “bag” is suitable, designed for a current of 25 A and allowing you to open both wires at once. As practice shows, it does not make sense to install any kind of fuses (anti-overload machines) on the welding machine. Here you have to deal with such currents, if exceeded, the protection at the network input to the apartment will definitely work. For the manufacture of the secondary winding, the casing-guard, the current-collecting slider and the mounting fittings are removed from the base LATR2. Then, on the existing 250 V winding (127 and 220 V taps remain unclaimed), reliable insulation is applied (for example, from varnished fabric), on top of which a secondary (lowering) winding is placed. And this is 70 turns of an insulated copper or aluminum bus, having a diameter of 25 mm2. It is acceptable to make the secondary winding from several parallel wires with the same overall cross section. Winding is more convenient to carry out together. While one, trying not to damage the insulation of adjacent turns, carefully stretches and lays the wire, the other holds the free end of the future winding, preventing it from twisting. The upgraded LATR2 is placed in a protective metal casing with ventilation holes, on which is placed a circuit board made of 10 mm getinax or fiberglass with a batch switch SB1, a thyristor voltage regulator (with resistor R6), a light indicator HL1 for turning on the device in the network and output terminals for welding on an alternating (X2, X3) or direct (X4, X5) current. In the absence of a basic LATR2, it can be replaced with a home-made "welder" with a magnetic circuit made of transformer steel (core cross section 45-50 cm2). Its primary winding should contain 250 turns of PEV2 wire with a diameter of 1.5 mm. The secondary one is no different from the one used in the modernized LATR2. At the output of the low-voltage winding, a rectifier unit with power diodes VD3-VD10 is installed for DC welding. In addition to these valves, more powerful analogues are quite acceptable, for example, D122-32-1 (rectified current - up to 32 A). Power diodes and thyristors are installed on radiators-heat sinks, the area of each of which is at least 25 cm2. The axis of the adjusting resistor R6 is brought out of the casing. A scale with divisions corresponding to specific values of direct and alternating voltage is placed under the handle. And next to it is a table of the dependence of the welding current on the voltage on the secondary winding of the transformer and on the diameter of the welding electrode (0.8-1.5 mm). Of course, self-made electrodes made of carbon steel "wire rod" with a diameter of 0.5-1.2 mm are also acceptable. Blanks 250-350 mm long are covered with liquid glass - a mixture of silicate glue and crushed chalk, leaving the 40-mm ends unprotected, which are necessary for connecting to the welding machine. The coating is thoroughly dried, otherwise it will start to “shoot” during welding. Although both alternating (terminals X2, X3) and direct (X4, X5) current can be used for welding, the second option, according to welders, is preferable to the first. Moreover, polarity plays an important role. In particular, when a "plus" is applied to the "mass" (the object being welded) and, accordingly, the electrode is connected to the terminal with the "minus" sign, the so-called direct polarity takes place. It is characterized by the release of more heat than with reverse polarity, when the electrode is connected to the positive terminal of the rectifier, and the “mass” to the negative. Reverse polarity is used when it is necessary to reduce heat generation, for example, when welding thin sheets of metal. Almost all the energy released by the electric arc goes to the formation of a weld, and therefore the depth of penetration is 40-50 percent greater than with a current of the same magnitude, but with direct polarity. And a few other very important features. An increase in the arc current at a constant welding speed leads to an increase in the penetration depth. Moreover, if the work is carried out on alternating current, then the last of these parameters becomes 15-20 percent less than when using direct current of reverse polarity. The welding voltage has little effect on the depth of penetration. But the width of the seam depends on Uw: with increasing voltage, it increases. Hence an important conclusion for those involved in, say, welding work when repairing a car body made of sheet steel: the best results will be obtained by welding with direct current of reverse polarity at a minimum (but sufficient for stable arcing) voltage. The arc must be kept as short as possible, then the electrode is consumed evenly, and the depth of penetration of the welded metal is maximum. The seam itself is clean and strong, practically devoid of slag inclusions. And from rare splashes of the melt, which are difficult to remove after the product has cooled, you can protect yourself by rubbing the near-weld surface with chalk (the drops will roll off without sticking to the metal). The arc excitation is carried out (after applying the corresponding -Usv to the electrode and the “mass”) in two ways. The essence of the first is in a light touch of the electrode on the parts to be welded, followed by its withdrawal by 2-4 mm to the side. The second method is reminiscent of striking a match on a box: sliding the electrode over the surface to be welded, it is immediately taken away for a short distance. In any case, you need to catch the moment of the arc and only then, smoothly moving the electrode over the seam formed right there, maintain its calm burning. Depending on the type and thickness of the metal to be welded, one or another electrode is selected. If, for example, there is a standard assortment for a St3 sheet with a thickness of 1 mm, electrodes with a diameter of 0.8-1 mm are suitable (this is basically what the design under consideration is designed for). For welding work on 2 mm rolled steel, it is desirable to have both a more powerful "welder" and a thicker electrode (2-3 mm). For welding jewelry made of gold, silver, cupronickel, it is better to use a refractory electrode (for example, tungsten). Metals that are less resistant to oxidation can also be welded using carbon dioxide protection. In any case, work can be performed both with a vertically located electrode, and tilted forward or backward. But sophisticated professionals say: when welding with a forward angle (meaning an acute angle between the electrode and the finished seam), more complete penetration and a smaller width of the seam itself are provided. Backward welding is recommended only for lap joints, especially when dealing with profiled steel (angle, I-beam and channel). An important thing is the welding cable. For the device in question, copper stranded (total cross section is about 20 mm2) in rubber insulation is the best fit. The required quantity is two one and a half meter segments, each of which should be equipped with a carefully crimped and soldered terminal lug for connection to the “welder”. For a direct connection to the “mass”, a powerful alligator clip is used, and with an electrode, a holder resembling a three-pronged fork is used. You can also use the car "cigarette lighter". You also need to take care of your personal safety. When arc welding, try to protect yourself from sparks, and even more so from splashes of molten metal. It is recommended to wear loose-fitting canvas clothing, protective gloves and a mask that protects the eyes from the harsh radiation of the electric arc (sunglasses are not suitable here). Of course, we must not forget about the "Safety regulations when performing work on electrical equipment in networks with voltages up to 1 kV". Electricity does not forgive carelessness!

A common material for the manufacture of home-made welding transformers has long been burnt LATRs (laboratory autotransformers). Inside the LATR case there is a toroidal autotransformer made on a magnetic circuit of a significant cross section. It is this magnetic circuit that will be needed from LATR for the manufacture of a welding transformer. A transformer usually requires two identical magnetic rings from large LATRs.

LATRs are produced in different types, with maximum currents from 2 to 10A, not all of them are suitable for the manufacture of transformers for welding, only those whose magnetic core sizes allow you to lay the required number of turns. The most common among them is probably the autotransformer of the LATR-1M type. Depending on the winding wire, it is designed for currents of 6.7-9A, although the dimensions of the autotransformer itself do not change from this. The LATR-1M magnetic circuit has the following dimensions: outer diameter D=127 mm, inner diameter d=70 mm, ring height h=95 mm, section S=27 cm2, weight about 6 kg. A good welding transformer can be made from two rings from LATR-1M, however, due to the small internal volume of the window, you cannot use too thick wires and you will have to save every millimeter of window space. A significant disadvantage of the transformer from LATRs, in comparison with the scheme of the U-shaped transformer, is also that it is impossible to manufacture coils separately from the magnetic circuit. This means that you have to wind, pulling each turn through the window of the magnetic circuit, which of course greatly complicates the manufacturing process.

There are LATRs with more voluminous magnetic rings. They are much better suited for making welding transformers, but are less common. For other autotransformers similar in parameters to LATR-1M, for example, AOSN-8-220, the magnetic core has different dimensions: the outer diameter of the ring is larger, but the height and diameter of the window d = 65 mm are smaller. In this case, the window diameter must be expanded to 70 mm.

The ring of the magnetic core consists of pieces of iron tape wound on top of each other, fastened at the edges by spot welding. In order to increase the inner diameter of the window, it is necessary to disconnect the end of the tape from the inside and unwind its required amount. But don't try to rewind everything at once. It is better to unwind one turn, each time cutting off the excess. Sometimes the windows of larger LATRs are also expanded in this way, although this inevitably reduces the cross-sectional area of the magnetic circuit.

In principle, a cross-sectional area and one ring would suffice for a welding transformer. But the problem is that smaller area magnetic circuits inevitably require more turns, which increases the volume of the coils and requires more window space.

Split-arm transformer

At the beginning of the manufacture of the transformer, it is necessary to insulate both rings. In this case, special attention should be paid to the corners of the edges of the rings - they are sharp, they can easily cut the superimposed insulation, and then close the winding wire. It is better to first smooth the corners with a file, and then apply some strong and elastic tape along the length, for example, a dense keeper or a cambric tube cut along. From above, the rings, each separately, are wrapped with a thin layer of fabric insulation.

Next, the isolated rings are connected together. The rings are tightly pulled together with a strong tape, and on the sides they are fixed with wooden pegs, also then tied with a tape - the core of the magnetic circuit for the transformer is ready.

The next step is the most important - laying the primary winding. The windings of this welding transformer are wound according to the scheme: primary in the middle, two sections of the secondary on the side arms.

The primary winding takes about 70-80 m of wire, which will have to be pulled through both windows of the magnetic circuit with each turn. In this case, you can not do without a simple device.

First, the wire is wound on a wooden reel and, in this form, is pulled through the windows of the rings without any problems.

The primary winding wire may have a diameter of 1.6-2.2 mm. For magnetic circuits made up of rings with a window diameter of 70 mm, a wire with a diameter of not more than 2 mm can be used, otherwise there will be little space for the secondary winding. The primary winding contains, as a rule, 180-200 turns at normal mains voltage, which is sufficient for efficient operation of a 3 mm electrode.

A cambric is put on the end of the wire, which is attracted by the HB tape to the beginning of the first layer. The surface of the magnetic circuit has a rounded shape, so the first layers will contain fewer turns than subsequent ones - to level the surface.

The wire lies coil to coil, in no case allowing the wire to overlap the wire. The wire layers must be insulated from each other. Again, to save space, the winding should be placed as compactly as possible. On a magnetic core of medium-sized rings, the interlayer insulation should be used thinner. One should not strive to wind the primary winding quickly. This process is slow, and after laying hard wires, fingers begin to hurt. It is better to do this in 2-3 approaches - after all, quality is more important than speed.

If the primary winding is made, most of the work is done, the secondary remains. But first you need to determine the number of turns of the secondary winding for a given voltage. To get started, turn on the ready-made primary network. The no-load current of this version of the transformer is small - only 70-150 mA, the rumble of the transformer should be barely audible. We wind 10 turns of any wire on one of the side arms and measure the output voltage on them. Each of the side arms accounts for half of the magnetic flux created on the central arm, so here for each turn of the secondary winding there is 0.6-0.7V. Based on the result obtained, the number of turns of the secondary winding is calculated, focusing on a voltage of 50V (about 75-80 turns).

The choice of material for the secondary winding is limited by the remaining space of the windows of the magnetic circuit. Moreover, each turn of a thick wire will have to be pulled along the entire length into a narrow window. The easiest way is to wind the usual stranded wire 16 mm 2 in synthetic insulation - it is soft, flexible, well insulated, it will only heat up slightly during operation. It is possible to make a secondary winding from several strands of copper wire.

Half of the turns of the secondary winding is wound on one shoulder, half on the other. If there are no wires of sufficient length, you can connect them from pieces - it's okay. Having wound the windings on both arms, you need to measure the voltage on each of them, it may differ by 2-3V - the slightly different properties of the magnetic circuits of different LATRs affect, which does not particularly affect the properties of the arc during welding. Then the windings on the shoulders are connected in series, but care must be taken that they are not in antiphase, otherwise the output will be a voltage close to zero (see the article Winding a welding transformer). With a mains voltage of 220-230V, a welding transformer of this design should develop a current of 100-130A in arc mode. Current in case of short circuit of the secondary circuit - up to 180A.

It may turn out that it was not possible to fit all the calculated turns of the secondary winding into the windows, and the output voltage turned out to be lower than desired. The operating current will decrease from this not much. To a greater extent, lowering the open circuit voltage affects the process of arc ignition. The arc ignites easily at voltages close to 50V and above. Although the arc can be ignited without any problems at lower voltages. So if the manufactured transformer has an output of about 40V, then it can be used for work. Another thing is if you come across electrodes designed for high voltages - some brands of electrodes work from 70-80V.

toroidal transformer

On rings from LATRs, it is also possible to make a welding transformer according to a different - toroidal scheme. This also requires two rings, preferably from large LATRs. The rings are connected and insulated: one ring-magnetic circuit with a significant cross-sectional area is obtained.

The primary winding contains the same number of turns as in the previous circuit, but is wound along the entire length of the ring and, as a rule, lies in two layers. The problem of the shortage of the internal space of the magnetic circuit window of such a transformer circuit is even more acute than for the previous design. Therefore, it is necessary to isolate here with as thin layers and materials as possible. It is impossible to use thick winding wires here. Although in some installations LATRs of especially large sizes are used, a toroidal welding transformer can be made on only one ring of this type.

An advantageous difference between a toroidal circuit for a welding transformer is a higher efficiency. Each turn of the secondary winding will now have more than one volt of voltage, therefore, the "secondary" will have fewer turns, and the output power will be higher than in the previous circuit. However, the length of the turn on the toroidal magnetic circuit will be longer, and it is unlikely that it will be possible to save on the wire here. The disadvantages of this scheme include: the complexity of winding, the limited volume of the window, the impossibility of using a wire of large cross section, as well as the high intensity of heating. If in the previous version all the windings were separate and at least partially had contact with air, now the primary winding is completely under the secondary, and their heating is mutually enhanced.

It is difficult to use hard wires for the secondary winding. It is easier to wind it with soft stranded or multi-core wire. If you correctly select all the wires and carefully lay them, then the required number of turns of the secondary winding will fit into the space of the magnetic circuit window and the desired voltage will be obtained at the output of the transformer.

Sometimes a toroidal welding transformer is made from several rings of LATRs in a different way, they are not put on top of each other, but the iron strips of the tape are rewound from one to the other. To do this, first, the inner turns of the strips are selected from one ring in order to expand the window. The rings of other LATRs are completely unfolded into strips of tape, which are then wound as tightly as possible on the outer diameter of the first ring. After that, the assembled single magnetic core is wrapped very tightly with insulating tape. Thus, a ring-magnetic circuit is obtained with a more voluminous internal space than all the previous ones. In this it will be possible to accommodate a wire of considerable cross section. The required number of turns is calculated from the cross-sectional area of the assembled ring.

The disadvantages of this design include the complexity of manufacturing the magnetic circuit. Moreover, no matter how hard you try, you still won’t be able to manually wind the iron strips on top of each other as tightly as before. As a result, the magnetic circuit turns out to be flimsy. When working in the welding mode, the iron in it vibrates strongly, emitting a powerful hum.

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When building or repairing appliances or household appliances, quite often there is a need for welding of any elements. To connect the parts, you will need to use a welding machine. Today, you can easily purchase a similar design, but you should know that home-made welding machines can also be made.

Welding machines are of direct and alternating current. The latter are used in order to weld workpieces from metal of small thickness at low currents. The arc of DC welding is more stable, while it is possible to weld in direct and reverse polarity. In this case, you can use an electrode wire without coating or electrodes. To give stability to the burning of the arc, at low currents it is recommended to make an overestimated open-circuit voltage of the welding winding.

To rectify alternating current, ordinary bridge rectifiers on large semiconductors with cooling radiators should be used. In order to smooth out voltage ripples, one of the leads must be connected to the electrode holder through a special choke, which is a coil of several tens of turns of a 35 mm copper bus bar. Such a bus can be wound on any core, it is best to use a core from a magnetic starter.

In order to rectify and smoothly regulate the welding current, more complex circuits should be used using large thyristors for control.

The advantages of constant current regulators include their versatility. They have a wide range of voltage configurations, and therefore such elements can be used not only for gradual current regulation, but also for charging batteries, powering electrical elements for heating and other circuits.

AC welding machines can be used to connect workpieces with electrodes whose diameter is more than 1.6 mm. The thickness of the connected workpieces can be more than 1.5 mm. In this case, there is a large welding current, and the arc burns stably. Electrodes that are made for welding exclusively on alternating current can be used.

Stable arc burning can be obtained if the welding fixture has a falling external characteristic, which determines the relationship between current and voltage in the welding chain.

What should be considered in the process of manufacturing welding machines?

For stepwise overlapping of the spectrum of welding currents, switching of both primary and secondary windings is necessary. For a smooth current configuration within the selected spectrum, the mechanical properties of winding movement should be used. If you remove the welding winding in relation to the mains winding, the leakage magnetic fluxes will increase. It should be understood that this can lead to a decrease in welding current. In the process of manufacturing a home-made structure for welding, it is not necessary to strive for a complete overlap of the spectrum of welding currents. It is recommended to first assemble to work with electrodes 2-4 mm. If you need to work at low welding currents in the future, the design can be supplemented with a separate device for straightening with a gradual adjustment of the welding current.

Homemade designs must satisfy some requirements, the main of which are the following:

Relatively compact and light weight. Such parameters can be reduced by reducing the power of the structure.
Sufficient duration of work from the mains 220 V. It can be increased by using steel with high magnetic permeability of heat-resistant insulation of wires for winding.

Such requirements can be easily met if you know the basics of the construction of welding structures and adhere to the technology of their manufacture.

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How to choose the type of core for the manufactured structure?

In the process of manufacturing such structures, rod magnetic wires are used, they are more technologically advanced. The core is assembled from electrical steel plates of any configuration, the thickness of the material should be 0.35-0.55 mm. The elements will need to be pulled together with studs that are covered with insulating material.

In the process of choosing the core, the dimensions of the "window" should be taken into account. Windings of elements should be placed in the design. It is not recommended to use cores with a cross section of 25-35 mm, since in this case the manufactured structure will not have the necessary power reserve, as a result of which high-quality welding will be quite difficult to produce. In this case, overheating of the device cannot be ruled out either. The core should be a section of 45-55 mm.

In some cases, welding structures with toroidal cores are produced. These devices have higher electrical performance and low power losses. It is much more difficult to make such devices, since the windings will need to be placed on the torus. You should know that winding in this case is quite difficult to perform.

The cores are made of strip transformer iron, which is rolled into a torus-shaped roll.

To increase the inner diameter of the torus, from the inside you need to unwind part of the metal tape, and then wind it on the outer side of the core.

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How to choose the right winding design?

For the primary winding, it is recommended to use copper wire, which is covered with fiberglass insulating material. You can also use wires that are covered with rubber. Do not use cords that are covered with PVC insulation.

A large number of taps of the network winding is not recommended. By reducing the number of turns of the primary winding, the power of the welding machine will increase. This will lead to an increase in the arc voltage and a deterioration in the quality of the connection of the workpieces. By changing the number of turns of the primary winding, it will not be possible to achieve overlapping of the welding current spectrum without deteriorating the welding properties. To do this, it will be necessary to provide for switching turns of the secondary welding winding.

The secondary winding should contain 67-70 turns of a copper bar with a cross section of 35 mm. You can use a stranded network cable or a flexible stranded cord. The insulating material must be heat-resistant and reliable.

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Homemade autotransformer welding machine

The welding device is powered by 220 V. The design has excellent electrical performance. Thanks to the use of a new form of magnetic wire, the weight of the fixture is about 9 kg with dimensions of 150x125 mm. This is achieved by using a band of iron, which is rolled into a torus-shaped roll. In most cases, a standard W-shaped record package is used. The electrical performance of the transformer structure on a magnetic wire is approximately 5 times higher than that of similar plates. Power loss will be minimal.

Elements that will be needed in order to make a welding machine with your own hands:

magnetic wire;
autotransformer;
electric cardboard or lacquer cloth;
wires;
wooden rail;
insulating material;
transformer;
cable;
casing;
switch.

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