How to make a welding inverter from a computer power supply

The welding inverter from the computer power supply unit with their own hands is becoming more and more popular both among professionals and amateur welders. The advantages of such devices are that they are comfortable and light.

Welding inverter device

The device welding inverter.

The use of an inverter power source allows you to qualitatively improve the characteristics of the welding arc, reduce the size of the power transformer and thereby lighten the weight of the device, makes it possible to make more smooth adjustments and reduce spatter during welding. The minus of the inverter type welding machine is a significantly higher price than the transformer counterpart.

In order not to overpay in the stores large sums of money for welding, you can make a welding inverter with your own hands. This requires a working computer power supply, several electrical appliances, tools, basic knowledge and practical skills in electrical work. Also, it will be useful to acquire the appropriate literature.

If you are not confident in your abilities, then you should turn to the store for a finished welding machine, otherwise with the slightest error in the assembly process there is a risk of getting an electric shock or burning all electrical wiring. But if you have experience in assembling circuits, rewinding transformers and creating electrical appliances with your own hands, you can safely proceed to assembly.

The principle of operation of inverter welding

Inverter schematic diagram

Schematic diagram of the inverter.

The welding inverter consists of a step-down voltage network of a power transformer, stabilizing chokes, reducing current ripple, and an electrical circuit block. For circuits you can use MOSFET or IGBT transistors.

The principle of operation of the inverter is as follows: alternating current from the network is sent to the rectifier, after which the power module converts direct current into alternating current with increasing frequency. Next, the current enters the high-frequency transformer, and at the output of it turns out the current of the arc.

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Tools needed to make an inverter

To assemble the welding inverter from the power supply with your own hands, you will need the following tools:

TL494 voltage feedback circuit in a computer power supply

TL494 voltage feedback circuit in a computer power supply.

  • soldering iron;
  • screwdrivers with different tips;
  • pliers;
  • clippers;
  • drill or screwdriver;
  • crocodiles;
  • wires of the necessary section;
  • tester;
  • multimeter;
  • consumables (wires, solder for soldering, electrical tape, screws and others).

To create a welding machine from a computer power supply, materials are needed to create a printed circuit board, getinax, spare parts. To reduce the amount of work, you should contact the store for ready holders for electrodes. However, you can make them yourself, soldering crocodiles to the wires of the required diameter. In this work, it is important to observe polarity.

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Assembly procedure of the welding machine

First of all, to create a welding machine from a computer power supply, you need to get the power source from the computer case and disassemble it. The main elements that can be used from it are a few spare parts, a fan and standard housing plates. It is important to consider the cooling operation mode. It depends on what elements to provide the necessary ventilation.

Transformer circuit with primary and secondary winding

The scheme of the transformer with the primary and secondary winding.

The operation of a standard fan, which will cool the future welding machine from a computer unit, needs to be tested in several modes. This check will make sure that the item is working. To ensure that the welding machine does not overheat during operation, an additional, more powerful source of cooling can be supplied.

To control the required temperature, install a thermocouple. The optimum temperature for the welding machine operation should not exceed 72-75 ° С.

But first of all it is necessary to install a handle for carrying and convenience of work on a welding machine from a computer power unit of the required size. The handle is installed on the top panel of the unit with screws.

It is important to choose screws that are optimal in length; otherwise, too large ones may touch the internal circuit, which is unacceptable. At this stage of work should worry about good ventilation apparatus. The placement of the elements inside the power supply is very dense, so a large number of through holes should be arranged in advance. They are performed by a drill or screwdriver.

Further, to create an inverter circuit, you can use several transformers. Usually choose 3 transformers of type ETD59, E20 and Kx20x10x5. You can find them in almost any electronics store. And if you already have experience of creating transformers yourself, then it is easier to do them yourself, focusing on the number of turns and the operating characteristics of transformers. Find such information on the Internet is not difficult. You may need a current transformer K17x6x5.

Ways to connect a welding inverter

Ways to connect a welding inverter.

It is best to perform home-made transformers from getinax coils, the winding will be enamel-wire, with a cross section of 1.5 or 2 mm. You can use copper tin 0.3x40 mm, after wrapping it with strong paper. Suitable thermal paper from the cash register (0.05 mm), it is durable and not so torn. Crimping should be done from wooden pads, after which the entire structure should be filled with “epoxy” or varnished.

Creating a welding machine from a computer unit, you can use a transformer from a microwave oven or old monitors, not forgetting to change the number of windings. In this work, it will be useful to use electrical literature.

As a radiator, you can use PIV, pre-sawn into 3 parts, or other radiators from old computers. You can buy them in specialized stores engaged in disassembling and upgrading computers. Such options will allow you to save time and effort in finding the right cooling.

To create an apparatus from a computer power supply unit, one must always use a single-ended forward-path quasi-symmetric bridge, or “oblique bridge”. This element is one of the main things in the welding machine, so it’s better not to save on it, but to buy a new one in the store.

Printed circuit boards can be downloaded on the Internet. This will greatly facilitate the re-creation of the scheme. In the process of creating the board will need capacitors, 12-14 pieces, 0.15 microns, 630 volts. They are necessary to block the resonant current surges from the transformer. Also, to make such a device from a computer power supply, you will need capacitors C15 or C16 with the mark K78-2 or SVV-81. Transistors and output diodes should be installed on radiators without using additional pads.

In the course of work, it is necessary to constantly use a tester and a multimeter in order to avoid errors and for faster assembly of the circuit.

Electric circuit welding semiautomatic device

Electric circuit welding semiautomatic.

After all the necessary parts have been manufactured, they should be placed in the housing with their subsequent installation. The temperature on the thermocouple should be set to 70 ° C: this will protect the entire structure from overheating. After assembly, the welding machine from the computer unit must first be tested. Otherwise, with the error made during the assembly, you can burn all the main elements, or even get an electric shock.

On the front side, two contact holders and several current regulators should be installed. The switch of the device in this design will be a standard toggle switch of the computer unit. The body of the finished unit after assembly is required to be further strengthened.

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Advantages of the welding machine from a computer power supply

A self-made welding machine will be small and light. It is perfect for home welding, it is convenient to cook on it with a two or three electrodes, without experiencing problems with "flashing light" and without fear of wiring. The power supply for such a welding machine can be any home socket, and during operation such a device will practically not spark.

By making a welding inverter with your own hands, you can significantly save on the purchase of a new device, but this approach will require considerable expenditure of both effort and time. After assembling the finished sample, you can try to make your changes to the welding machine from the computer unit and its scheme, to make lightweight models of greater power. And by making such devices for acquaintances to order, you can secure a decent additional income.

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