Do-it-yourself welding machines for the home are most often created by craftsmen from scrap materials.
If you do not have the opportunity or desire to buy a welding machine, then you can assemble it yourself using ready-made elements.
However, to speed up the assembly process, ready-made components and parts can be used. A holder for electrodes can also be made on our own from those available in the arsenal home handyman materials.
The simplest welding machine
In a home craftsman's household, you may find a step-down transformer S-B22, IV-10, IV-8, the power of which is 1-2 kW. It reduces the voltage from 220 V to 36 V and serves to power power tools.
Welding machines based on such transformers can be assembled even with a failed winding.
The welding machine is manufactured as follows:
The secondary winding must be removed from the transformer.
- secondary windings are removed from the coils without damaging the primary ones;
- the middle primary coil is rewound with the same wire, creating taps after 30 turns total number 8-10 pcs. (for convenience, it is better to number each of them as they are created);
- the two outer coils are filled with a multi-core cable (three 6-8 mm wires with a thin phase, 12-13 m are consumed for each coil);
- a copper pipe with a diameter of 10-12 mm is used for the terminal for the VO cable (one side crimps the wires, the other is flattened, drilled for fasteners with a diameter of 10 mm);
- on the top panel of the transformer, the M6 fasteners are replaced with a more powerful one (M10), and the VO terminals are attached to them;
- A board with 10 holes for software is made from PCB, and an M6 fastener is inserted into each hole.
Welding machines of this design are powered by a 380/220 V network. In the first case, the end coils are connected in series, then the middle coils. In the second option, the outer windings are connected in parallel, the middle one is connected in series to the same circuit. The VO taps are placed in the terminals of the textolite plate 1 - 10. The current is regulated by terminals 1 - 10.
It is not recommended to carry out large volumes of work with this SA (maximum 15 “troika” electrodes).
To cut metal, the second end of the cable leading to the holder is connected to the cutting terminal (on the side of the middle PO coil). The characteristics of the VO current correspond to 60-120 A, in the software the current is always 25 A. When working with “two” electrodes, the transformer does not heat up above +70˚C, so the operating time is not limited. Welding/cutting modes are switched when the switch is turned off.
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Machine for welding from car batteries
In order to invent a diesel generator for a welding machine, it is necessary to connect a pair of batteries in a certain sequence.
The welding machine seriously loads the household electrical network, providing a voltage surge of 30 V at a load of 3.5 kW. Instead of purchasing a welding diesel generator, the craftsmen created an original device circuit, the basis of which is 3-4 series-connected batteries from passenger car. The capacity of each of them must be at least 55-190 A/h; reliable clamps must be used to combine them into a common circuit.
This scheme is indispensable in field conditions, since even used batteries delivered to the site by a passenger vehicle will help out. It is necessary to take into account the strong heating of battery cases after several hours of operation, check the level and density of the electrolyte daily with constant use. In hot weather, water evaporates rapidly from the electrolyte, so control devices (hydrometer), distilled water, and acid should be kept at hand.
Welding machines of this type simply need to be charged at night by connecting the appropriate device to a common circuit so that all batteries are charged at once. When welding with electrodes with a diameter of 3 mm, the working current is no more than 90-120 A, which does not exceed half the power. The electrolyte does not boil due to its high heat capacity. The output voltage depends entirely on the number of batteries connected to the circuit and is 42-54 V.
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Homemade toroidal welding machine
U-shaped and W-shaped transformers are significantly inferior to toroids in terms of weight and size. A toroidal welding machine is one and a half times lighter than its W-shaped counterpart, but the main difficulty in self-production lies in the lack of necessary iron. Craftsmen share recommendations for making a transformer from an industrial CA that has exhausted its service life. A similar replacement would be the TCA 310 or TS 270 transformer. Its U-shaped plates are “halved” with a chisel and adjusted on an anvil.
Welding machines of this type are assembled from 45 x 9 cm plates:
- a plate riveted hoop with a diameter of 26 cm is filled with plates end to end (the work is done by two people, a partner fixes the core being assembled, preventing the plates from straightening);
- when the internal diameter of the structure reaches 12 cm, the set stops;
- parts are cut out of electrical cardboard: a strip 9 cm wide, rings with internal diameter 11 cm, external 27 cm;
- the rings are applied to the sides of the structure assembled at the first stage and wrapped with fabric tape;
- winding I is laid on electrical tape - 170 turns (for 220 V) of wire with a diameter of 2 mm, grade PEV-2;
- winding II is laid on top of it - 30 turns of wire with a diameter of 15-20 mm, grade PEV-3;
- winding III - 30 turns with MGTF 0.35 wire;
- insulation from each other with tape, the software is checked for the XX current: if it is less than 1-2 A, several turns are unwound; if the XX current is greater than 2 A, two turns are added.
This welding machine has an original control circuit in the form of a phase regulator. The voltage removed from winding III is rectified by a diode bridge. The capacitor is charged through resistors up to 6 V, then a breakdown occurs through a dinistor assembled from a thyristor and a zener diode. The diode with the thyristor opens. The last resistor in the circuit limits the current; when the alternating current wave is negative, the response thyristor and diode open. Welding machines of this design are tuned with a resistor.
To create a welding machine, resistors with a power of 10 W or more are required.
The scheme uses:
- diodes for a current of 160-250 A, mounted on radiators with an area of 100 cm2;
- capacitor K50-6;
- resistors with a power of 10 W;
- thyristors KU202 or KU201.
The welding machine confidently welds with electrodes with a diameter of 4 mm and cuts metal. You can make a holder for it yourself from an equal angle corner 10 cm long (shelves 2 cm each). A hole with a diameter of 4.1 mm is drilled 1 cm from the edge of the corner in the very corner, through which the burnt electrode can be pushed out with a new electrode. The lower part of the shelves will be narrowed according to the welder's hand. In internal corner a wire bent vertically upward from it is welded. A piece of rubber hose is placed on the structure from below. During operation, the electrode is inserted between the edges of the angle and pressed against them with a piece of welded wire.
Nowadays it is difficult to see any work with metal being carried out without the use of a welding machine. This device freely cuts or joins iron parts, regardless of its thickness and size. To do welding, you need to have some skills, and, in fact, the machine itself. You can buy it, you can hire a welder to carry out necessary work, or you can make the unit yourself.
Standard diagram of a welding machine and its types
Before you start creating a welding machine at home, you should understand its structure.
The main element of the welder that it consists of is a transformer that powers the arc of the device, controls alternating voltage and controls the quality and magnitude of the current.
The designs of standard welding machines are very diverse, but the following main types can be distinguished:
- AC apparatus;
- Working with direct current;
- Three-phase;
- Inverter.
DC welding is usually used to work with thin sheet material, automotive and roofing steel.
Welding devices of direct and alternating current are reliable, unpretentious in operation, heavy in weight and very sensitive to voltage changes. If it drops below 200 volts, it will be difficult to operate and there will be problems with ignition and maintaining the arc.
These welding machines are very similar in design, and if we have alternating current welding, then by modifying it a little, we will get a device for working with direct current.
As for inverters, thanks to the use of electronic parts, their weight has become much lighter. They are not afraid of voltage drops, but are very sensitive to overheating. You need to work with such devices carefully, otherwise they may break.
Homemade AC welding machine
A welding unit operating with alternating current is one of the most common models. It is the easiest to use and easy to assemble at home compared to other types of welders.
What is needed for this:
- Wires for secondary and primary windings;
- Winding core;
- Step-down transformer (you can take "LATRA").
What wires are needed? The optimal voltage when operating a device created independently is 60V with an optimal current of 120 -160A. Based on this, we understand that the minimum cross section copper wires to wind the primary, there should be 3-4 square meters. mm. Optimal – 7 sq. mm, which takes into account possible additional load and voltage surges.
Do not use wires with PVC or rubber insulation, as they may overheat and cause a short circuit.
If there is no wire the required section, you can use thin strands wound together. True, the thickness of the winding will increase, which will entail an increase in the dimensions of the device itself. To make a secondary winding, you can take a thick copper wire consisting of many cores.
The homemade core is made from a transformer steel plate, the thickness of which should be from 0.35 mm to 0.55 mm. They must be folded to form a core required thickness, and then secure the device with bolts at the corners. At the end of the work, you should use a file to process the surface of the plates and make insulation.
Then the winding begins. First, the primary one (about 240 turns can be made). In order to be able to regulate the passing current, you need to make several taps with an approximate step of 20-25 turns.
How much copper is needed for the secondary winding? Typically the number of turns is 65-70. Wire cross-section – 30 – 35 sq mm. As with the primary winding, taps must be made to regulate the current. The insulation of the wires must be reliable and resistant to heat.
Winding is done in one direction and each layer is insulated. The ends of the winding are bolted to the plate and we can assume that the homemade welder is ready.
If you need to increase the current, a voltage boost can help in this matter, or you can do it manually by reducing the number of turns of the primary winding and switching the wire to a contact with a smaller number of turns.
When creating a welding machine, you must remember to ground it, in accordance with safety regulations. You should also always ensure that the welding machine does not overheat!
Simple DC Welding Machine
To weld cast iron and stainless steel, you will need a machine with direct current. You can create it in 15 minutes if you already have an AC device. In this case, an existing device will be upgraded.
Remaking the alternator will consist of connecting a rectifier, which is assembled using diodes, to the secondary winding. The diodes, in turn, must withstand a current of 200 A and be well cooled.
The rectifier will do its job better if you use 50V capacitors and a special inductor to regulate the current.
What you need to know when connecting the device to the network permanently:
- It is imperative to use a switch, which can disconnect the device from the network at any time;
- The cross-section of the wire for connection must be greater than or equal to 1.5 square meters. mm, and the current consumption in the primary winding is a maximum of 25 A.
The way a welder works is such that he needs to be given a rest from time to time. And it doesn’t matter whether it’s a semi-automatic or a handbrake. However, if the device operates on electrodes with a diameter of less than 3 mm, then there is no need to interrupt.
Inverter: how to make a welding machine with your own hands
The inverter can be assembled independently from small parts and wiring from a Soviet TV or vacuum cleaner.
Features of the inverter:
- The device operates with direct current and its smooth adjustment from 40 to 130 A;
- The highest current for the primary winding is 20A, the electrodes used should be no more than 3 mm;
- The electric holder must have a button, pressing which will supply voltage to the device.
All inverter elements are located on a special printed circuit board, and for better heat removal from the diodes, they are fixed to a special heat sink, which is screwed to the board. The board itself is usually made of fiberglass, approximately 1.5 mm thick.
For additional cooling of the circuit, you can use a fan fixed directly to the case in which the inverter is located.
With the help of such a device, you can safely weld non-ferrous and ferrous metals and thin sheet workpieces.
Three-phase welding machines are usually used for welding in industrial settings, so it makes no sense to make them at home.
Particularly popular are welders from Timval, Budyonny and thyristors.
Tips on how to make a welding machine at home: spot welding
One of the most convenient and economical mini welding in Lately became point-like, occurring by contact. In everyday life, such a thing is used for repairing household appliances and welding batteries.
Heating occurs using a pulse, and the pulse moment does not exceed one tenth of a second, that is, everything happens very quickly.
This type of mini-welding is created using a transformer from an old microwave, which will be modified during the creation of the device. The goal is the ability to obtain a short-term pulse at the output of at least 1000A.
The modification goes like this:
- Everything is removed from the transformer except the core and primary winding;
- A wire with a cross-section of at least 100 square meters is wound in place of the secondary winding. mm;
- The main thing here is to wrap the wire very tightly around the core.
As a result, the output should be about 5 volts, but if the power is too low, you can use another transformer. Then you need to check the voltage again. If it is no more than 2000 A, the microwelding machine is ready for use.
According to experts, making a welding machine with your own hands is not difficult.
However, to make it, you need to clearly understand why, for what work it will be used.
A homemade device is completed and assembled from available components and parts. A plasma mechanism can also be considered as an option for craftsmen.
Practice shows that with precise selection of components, the device will serve for a long time and reliably.
It is important that electrical diagram was as simple as possible. Sometimes they even use a microwave transformer.
The device must operate from a household AC voltage of 220 V.
If you choose 380 V as the operating voltage, the circuit and design of the device will become noticeably more complicated.
Block diagram of the welding machine
For production welding work devices operating on alternating and direct current are used.
The circuit of any device includes a transformer (it is possible to use a transformer from a microwave), a rectifier, a choke, a holder, and an electrode. It is in this sequence that the flow occurs electric current in a closed circuit.
The circuit is completed when between the electrode and metal blanks, which need to be connected, an electric arc occurs.
In order for the quality of the welded joint to be high, it is necessary to ensure stable combustion of this arc.
And to set the required combustion mode, a current regulator is used.
DC machines are used for welding elements made of sheet metal. With this welding method, you can use any electrodes and electrode wire without ceramic coating.
The electrode holder is connected to the rectifier through a choke. This is done in order to smooth out voltage ripples.
The inductor is a coil of copper wires that is wound on any core. The rectifier, in turn, is connected to the secondary winding of the transformer.
The transformer is connected to the household electrical network. The connection sequence is simple and clear.
AC voltage conversion is done using a step-down transformer.
According to Ohm's law, the voltage that is induced on the secondary winding of the transformer decreases, and the current increases from 4 amperes to 40 or more.
This is approximately the amount required for welding. In principle, this device can be called the simplest welding machine.
And use wires to attach the electrode holder to it. But it is impossible to use the holder for practical purposes, since the circuit does not contain other necessary elements.
And most importantly, it does not have a current regulator. As well as a rectifier and other elements.
The transformer is considered the main element of the welding machine. You can buy it or adapt one that is already in use.
Many craftsmen use a transformer from a microwave that has expired. Due to its dimensions and weight, a micropulse element always takes up a lot of space in the structure.
If we consider the welding unit as a whole, we can distinguish three main blocks that it includes:
- power unit;
- rectifier block;
- inverter block.
A homemade inverter device can be configured in such a way that it has minimum dimensions and weight.
Such devices, designed for use in household, are sold in stores today.
Advantages inverter device compared to traditional units are obvious. First of all, it should be noted that the device is compact, easy to use, and reliable.
Only one component in the parameters of this device is of concern - its high cost.
The most general calculations confirm that making such a device with your own hands is easier and more profitable.
The main elements can almost always be found among electrical machines and devices that end up in storage rooms. Or in a landfill.
The simplest current regulator can be made from a piece of heating coil, which is used in household electric stoves. The choke is made from a piece of copper wire.
Radio amateurs have come up with the simplest pulse welding method. It is used to attach wires to a metal board.
No complicated devices - just a choke and a couple of wires. A current regulator is also not needed. Instead, a fuse-link is connected to the circuit.
One electrode is connected to the board through an inductor.
The second one is a crocodile clip. The plug with wires is plugged into a household outlet.
The clamp with the wire is sharply applied to the board in the place where it needs to be welded. A welding arc occurs and at this moment the fuses located in the electrical panel may blow out.
This does not happen because the fuse link burns out faster. And the wire remains securely welded to the board.
Product contents
The homemade one is assembled in order to carry out minor work in the household.
All elements, electronic devices, wires and metal constructions must be assembled at a specific location. Where the product will be assembled.
The choke can be used from the fittings fluorescent lamp. You need to stock up more wires, preferably copper, of different sections.
If the throttle is in finished form If you couldn’t find it, then you need to make it yourself.
To do this, you will need a steel magnetic core from an old starter and several meters of copper wires with a cross-section of 0.9 square.
power unit
The main element of the power supply in the inverter is the transformer.
It can be converted from a laboratory autotransformer or used to remake a transformer from a microwave oven that has already served its useful life.
It is very important not to damage the primary winding when removing the transformer from the microwave oven.
The secondary winding is removed and rebuilt. The number of turns and diameter of copper wires is calculated depending on the pre-selected power of the welding machine.
The spot welding method is well implemented by a device made on a transformer from a microwave oven.
The rectifier is used to convert AC voltage to DC voltage. Main elements of this device are diodes.
It is switched into certain circuits, most often bridge circuits. An alternating current is supplied to the input of such a circuit, and a direct current is removed from the output terminals.
Diodes are selected with such power to withstand the initially specified loads. To cool them, special radiators made of aluminum alloys are used.
When marking the installation board, it is advisable to provide space for a choke, which is designed to smooth out pulses. The rectifier is assembled on a separate board, made of getinax or textolite.
Inverter block
The inverter converts D.C., coming from the rectifier, into an alternating one, which has a high oscillation frequency.
The conversion is done using electronic circuits on thyristors or powerful transistors.
If a voltage of 220 volts with a frequency of 50 Hz is supplied to the input terminals of the transformer, then a direct current of up to 150 Amperes and a voltage of 40 volts is fixed at the output terminals of the inverter.
These current settings allow welding metal parts from various alloys.
The electronic regulator allows you to select the mode appropriate for a specific operation.
Practice shows that a homemade welding machine, in terms of its characteristics, is not inferior to factory products.
Some time ago, mini welding inverters appeared in the retail chain. To achieve this miniaturization manufacturing companies it took years.
While craftsmen have long been able to make a plasma welding machine made by themselves.
They were pushed to this step by local conditions - cramped conditions in the workshop and the significant weight of factory inverters. A plasma device is an excellent way out of this situation.
And the fact that instead of copper wires the secondary winding of the transformer is made of copper tin has also been known for a long time.
Assembly sequence of the welding machine
When placing elements on a metal or textolite base, you need to follow a certain order. The rectifier must be located next to the transformer.
The choke is on the same board as the rectifier. The current regulator should be located on the control panel. The body of the device can be made of sheet steel or aluminum.
Or adapt a chassis from an old oscilloscope or even a computer system unit. It is very important not to “sculpt” the elements as close to one another as possible.
It is necessary to make holes in the walls to install cooling fans and constant air flow.
The board with thyristors and other elements is placed as far as possible from the transformer, which gets very hot during operation. Exactly the same as the rectifier.
With this simple welding machine you can cut thin metals, weld copper wires, engrave on a metal surface. Other applications can be found without any problems. This mini welding machine can be powered with a voltage of 12-24 V.
The welding machine is based on a high-voltage, high-frequency converter. Built on the principle of a blocking generator with a deep transformer feedback. The generator generates short-term electrical pulses, repeated at relatively large intervals. The clock frequency is in the range of 10-100 kHz.
The transformation ratio of this circuit will be 1 to 25. This means that if you apply a voltage of 20 V to the circuit, then the output should be about 500 V. This is not entirely true. Since any pulse transformer source or generator without load has powerful high-voltage pulses reaching a voltage of 30,000 V! Therefore, if you disassemble any Chinese pulse charger, you will see a soldered resistor parallel to the output capacitor. This is also a network load; without a resistor, the output capacitor will quickly leak due to excess voltage, or worse, it will explode.
Therefore, attention! The voltage at the transformer output is dangerous to life!
Mini welding machine diagram
Required parts:
- The transformer is homemade, the manufacturing procedure is described below.
- Resistors - 0.5-2 W power.
- The transistor used was FP1016, but it is difficult to find due to its specificity. Can be replaced with transistor 2SB1587, KT825, KT837, KT835 or KT829 by changing the polarity of the power supply. Another transistor with a collector current of 7 A, a collector-emitter voltage of 150 V, and a high gain (composite transistor) is also suitable.
Transformer manufacturing
The transformer is wound on a piece of ferrite rod from a radio receiver.- The collector winding is 20 turns of 1 mm wire.
- Base winding - 5 turns with a 0.5-1 mm rein.
- High-voltage winding - 500 turns with a drive of 0.14-0.25 mm.
Let's put together a diagram. If everything is in order, everything should start without problems. Since the operating frequency of the generator exceeds the sound frequency, you will not hear a squeak during operation, so you should not touch the output of the transformer with your hands.
Start the generator with a voltage of 12 Volts and increase if necessary.
The arc is ignited from a distance of 1 cm, indicating a voltage of 30 kV. High frequency prevents the burning arc from breaking, as a result of which the arc burns very stably. When using a copper electrode in close contact with another electrode, a plasma medium (copper plasma) is formed, resulting in an increase in the temperature of arc welding and cutting.
Welding machine testing by cutting and welding
We cut the razor blade with an arc.
We fuse copper wires up to 1 mm thick.
Thick copper wire was used as an electrode. It is clamped in a wooden match, since dry wood is also a good insulator.
If you liked this small welding machine, then you can make it and large sizes, and power. But be extremely careful.
Also, to increase power, you can assemble a generator using a push-pull circuit, and even on field effect transistors, as here - . In this case, the power will be decent.
Also, do not look at the bright arc discharges with the naked eye; use special safety glasses.
Watch a video of making a welding machine using a blocking generator
Welding work at home has long become commonplace. Availability of devices and Supplies, the opportunity to inexpensively attend welding courses, various training manuals for acquiring independent skills. All these factors make it possible to save on the labor costs of a professional welder and increase the efficiency of work.
However, if you carefully study the welding machine market, unpleasant aspects become clear:
- High-quality welders have a high cost; it is more profitable to hire a specialist several times (unless, of course, you do this work constantly).
- Affordable units have a number of disadvantages: low reliability, poor quality seam, dependence on supply voltage and type of consumables.
Hence the conclusion: if necessary high quality equipment for affordable price, you will have to make a welding machine from available materials with your own hands.
Before considering options for homemade welders, let’s look at the principle of their operation.
The operation of any unit is based on Ohm's law. At constant power, there is an inverse relationship between current and voltage. For normal operation, a current of 60–150 A is required. Only in this case will the metal in the welding zone melt. Let's imagine a welding machine that operates directly with a voltage of 220 volts. To achieve the required current, a power of 15–30 kW will be required. Firstly, for this it will be necessary to lay a separate power supply line: most connections to residential premises are limited technical specifications at the level of 5–10 kW. In addition, such a current will require wiring with a cross-section of at least 30 mm². You will have to cook in compliance with protective measures when working in electrical installations up to 1000 volts: rubber boots, gloves, work area fencing, etc.
Of course, it is impossible to ensure such conditions in reality.
Therefore, any welding machine converts the voltage (downward): at the output we obtain the desired current while maintaining reasonable power.
The optimal voltage value is 60 volts. At welding current 100 A is a completely acceptable 6 kW of power. How to convert voltage?
There are four main types of welding machines
Any of the listed devices can be assembled independently. Let's review manufacturing technologies by model:
Transformers (with or without rectifier)
The heart of a transformer is the core. It is assembled from transformer steel plates, which are quite problematic to make by hand. By hook or by crook raw material produced in factories construction teams, at scrap metal collection points. The resulting structure (usually in the form of a rectangle) must have a cross-section of no less than 55 cm². This is a rather heavy structure, especially after laying the windings.
During assembly, it is imperative to provide an adjusting screw, with which you can move the secondary winding relative to the stationary primary.
In order not to go into the complexity of calculating the cross-section of wires, we will take typical parameters:
- secondary current 100–150 A;
- open circuit voltage 60–65 volts;
- operating voltage when welding 18–25 volts;
- current on the primary winding is up to 25 A.
Based on this, the cross-section of the primary wire should be at least 5 mm², if done with a margin, you can take a wire of 6–7 mm². The insulation must be heat-resistant and made from a material that does not support combustion.
The secondary winding is made of wire (or better yet, a copper busbar) with a cross-section of 30 mm². The insulation is rag. Don't let the thickness scare you, the number of turns on the secondary is small.
The number of turns of the primary winding is determined by a coefficient of 0.9–1 turns per volt (for our parameters).
The formula looks like this:
W(number of turns) = U(voltage) / coefficient.
That is, with a network voltage of 200–210 volts, it will be about 230–250 turns.
Accordingly, if the secondary voltage is 60–65 volts, the number of its turns will be 67–70.
From a technical point of view, the transformer is ready. For ease of use, it is recommended to make a small margin on the secondary winding, with several branches (at 65, 70, 80 turns). This will allow you to work confidently in places with low network voltage.
Hiding the unit in the housing or leaving it open is a matter of safety of use. A typical DIY welding transformer looks like this:
The optimal material for the case is 10–15 mm textolite.
Adding a rectifier
A homemade powerful welding transformer from a circuit design point of view is a regular power supply. Accordingly, the rectifier is designed as simply as in a mains charger for mobile phone. Only the element base will look several orders of magnitude more massive.
As a rule, in simple diagram from diode bridge add a pair of capacitors that dampen rectified current pulses.
You can assemble a rectifier without them, but the smoother the current, the better the quality of the weld. To assemble the bridge itself, powerful diodes of the D161–250(320) type are used. Since a lot of heat is generated on the elements when loaded, it must be dissipated using radiators. Diodes are attached to them using bolted connection and thermal paste.
Of course, the radiator fins must either be blown by a fan or protrude above the case. Otherwise, instead of cooling, they will heat the transformer.
Mini welding transformer
If you do not need to weld rails or channels from 4–5 mm steel, you can assemble a compact welder for soldering steel wire (making frames for homemade products) or welding thin sheet metal. To do this, you can take a ready-made transformer from a powerful household appliance ( perfect option- microwave), and rewind the secondary winding. Wire cross-section 15–20 mm², power consumption no more than 2–3 kW.
The calculation of the circuit is carried out in the same way as for more powerful units. When assembling the rectifier, you can use less powerful diodes.
Micro welder
If the scope of application is limited to soldering copper wires (for example, when installing distribution boxes), you can limit yourself to a design the size of a couple of matchboxes.
Performed on transistor KT835 (837). The transformer is manufactured independently. In fact, it is a high-frequency boost converter.
Unlike traditional welders, this circuit uses high voltage, up to 30 kV. Therefore, care should be taken when working.
We wind the transformer on a ferrite rod. Two primary windings: collector (20 turns 1 mm), base (5 turns 0.5 mm). Secondary (boost) winding - 500 turns of 0.15 wire.
We assemble the circuit, solder the resistor circuit according to the circuit (so that the transformer does not overheat at idle), the device is ready. Power supply from 12 to 24 volts, with the help of such a device you can weld wire harnesses, cut thin steel, and join metals up to 1 mm thick.
As welding electrodes You can use a thick sewing needle.
Inverter (pulse power supply for welding)
A homemade inverter welding machine cannot be made simply “on the knee”. This will require a modern element base and experience in repairing and creating electronic devices. However, the scheme is not as scary as it is made out to be. There are a great many similar devices made, and they all work no worse than their factory counterparts. In addition, to create a pulse welding machine with your own hands, it is not necessary to purchase dozens of expensive radio components and ready-made components. Most of them, especially high-frequency elements for the power supply, can be borrowed from old TVs or power supplies from a computer. The cost is close to zero.
The inverter in question has the following characteristics:
- Load current on the electrodes: up to 100 A.
- Power consumption from a 220 volt network is no more than 3.5 kW (current about 15 A).
- Used electrodes up to 2.5 mm.
The illustration shows ready-made diagram, which has been repeatedly tested by many home craftsmen.
Structurally, the inverter consists of three elements:
- Power supply for the converter and control circuit. Made at an affordable price element base, using an optocoupler from an old computer power supply. When making a transformer yourself, the cost is almost zero: the parts are cheap. The values and names of radioelements are shown in the illustration.
- Capacitor charge delay unit (for starting arc). Made on the basis of KT972 transistors (absolutely not a shortage). Of course, transistors are installed on radiators. For switching, an ordinary automotive relay with a current load on the contacts of up to 40 A is sufficient. For manual control, ordinary circuit breakers (packets) of 25 A are installed. Output 300 volts - idling. At load the voltage is 50 volts.
- The current transformer is the most critical component. During assembly Special attention You should pay attention to the accuracy of the inductors. Some adjustments can be made using variable resistor(highlighted in red on the diagram). However, if the parameters are not consistent, the required arc power will not be achieved. PWM is implemented on the US3845 chip (one of the few parts that will have to be purchased). Power transistors are the same KT972 (973). Some elements in the diagram are imported, but they can easily be replaced with available domestic ones by searching for analogues on the datasheet website. The high-frequency unit is made from parts of a line transformer from a TV.
To the exit welding inverter working wires no longer than 2 meters are connected. The cross-section is at least 10 squares. When working with electrodes up to 2.5 mm, the current drop is minimal, the seam is smooth and even. The arc is continuous, no worse than the factory equivalent.
If there is active cooling (fans from the same computer unit power supply), the design can be compactly packed into a small case. Considering high-frequency converters, it is better to use metal.
Bottom line
The more complex the homemade welding machine, the greater the savings. Exactly simple transformers are more expensive due to the use of expensive copper in windings or transformer iron. Pulse blocks power supplies, especially if there are old parts from standard electrical appliances in stock, are practically free.
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