Simple electronic welding current regulator, diagram. A simple electronic welding current regulator, diagram Category: “Electronic homemade products”

Often you have to weld metal of different thicknesses and use electrodes of different diameters, and in order for the welding to be high-quality, it is necessary to adjust the welding current so that the seam lies evenly and the metal does not splash. But, regulating the current of the secondary winding of a welding transformer is quite problematic, because it can reach up to 180-250A.

As an option, nichrome spirals are used to regulate the welding current, including them in series in the circuit of the primary or secondary winding of the welding transformer, or chokes. It is inconvenient to regulate the current in this way, and the regulator itself is cumbersome. But there is another way out - to make an electronic welding current regulator that would regulate the current in the primary winding of the welding machine.

The welding current regulator for a homemade welding machine is also very useful in cases where you have to weld metal in places where the power grid is weak, for example in villages. As a rule, they limit the current consumption for each house by installing an input circuit breaker of 16 A, i.e. You cannot turn on a load of more than 3.5 kW. A good welding machine, welding with electrodes with a diameter of 4-5 mm, consumes 6-7, or even 8 kW.

Therefore, we reduced the welding current and at the same time reduced the current consumption of the welding machine, thus investing in those 3.5 kW and “C” welding what you need.

Here is a simple circuit of such a regulator with 2 thyristors and it has a minimum of non-scarce parts. It can be done with 1 triac, but, as practice has shown, it is more reliable with thyristors.

The welding current regulator works as follows: a regulator is connected in series to the primary winding circuit, which consists of two controlled thyristors VS1 and VS2 (T122-25-3, or E122-25-3), for each half-wave. The opening moment of the thyristors is determined by the RC circuit (R7, C1, C2). By changing the resistance R7, we change the opening moment of the thyristors and thereby change the current in the primary winding of the transformer, and therefore the current in the secondary winding also changes.

Transistors can be used of the old type - P416, GT308, their lekko can be found in old receivers or televisions, and capacitors are used like MBT or MBM for an operating voltage of at least 400 V.

Transistors VT1, VT2 and resistors R5, R6, connected as shown in the diagram, are an analogue of dinistors and in this embodiment they work better than dinistors, but if you really want, instead of VT1, R5 and VT2, R6 you can put ordinary dinistors - type KN102A.

When assembling and setting up the welding current regulator, do not forget that control occurs under a voltage of 220V. Therefore, in order to prevent electric shock, all radio elements, as well as thyristor heat sinks, must be insulated from the housing!

In practice, the above electronic welding current regulator has proven itself to be excellent.
The basis was taken from the magazine Radioamator. - 2000. - No. 5 “Do-it-yourself welding transformer.”

Power thyristors T122-25– pin-type powerful thyristors for general purpose. Converts and regulates direct and alternating current to 25A frequency up to 500 Hz in circuits with voltage 100V – 1600V(1-16 grades). Type of housing of thyristors of the T122-25 series – ST2: thread - M6, weight - 11 g. "ST" stands for "stud thyristor" - pin thyristor.

Pin layout(pinout): thyristor base – anode, hard long output – cathode, hard short output – control electrode.

Manufactured for use in temperate, cold (UHL) or tropical (T) climates; accommodation category – 2.

To remove heat, thyristors are assembled with coolers using a threaded connection. To ensure reliable thermal and electrical contact with the cooler during assembly, the torque Md for T122-25 thyristors should be 1.4-1.8 Nm. It is also recommended to use heat-conducting paste KPT-8.

Thyristors T122-25 are used in power supply circuits for electrical installations of direct and alternating current and in semiconductor power converters.

Technical characteristics, explanation of markings, dimensions, used coolers are listed below. The operation guarantee of the thyristors supplied by our company is 2 years from the date of purchase. Quality documents are provided.

The final price for T122-25 thyristors depends on the class, quantity, delivery time and form of payment.

Detailed characteristics of thyristors T122-25:

Decoding the markings of thyristors T122-25:

Attention!!! Delivery of ALL devices that are listed on the website takes place throughout the ENTIRE territory of the following countries: Russian Federation, Ukraine, Republic of Belarus, Republic of Kazakhstan and other CIS countries.

In Russia there is an established delivery system to the following cities: Moscow, St. Petersburg, Surgut, Nizhnevartovsk, Omsk, Perm, Ufa, Norilsk, Chelyabinsk, Novokuznetsk, Cherepovets, Almetyevsk, Volgograd, Lipetsk Magnitogorsk, Tolyatti, Kogalym, Kstovo, Novy Urengoy, Nizhnekamsk, Nefteyugansk, Nizhny Tagil, Khanty-Mansiysk, Yekaterinburg, Samara, Kaliningrad, Nadym, Noyabrsk, Vyksa, Nizhny Novgorod, Kaluga, Novosibirsk, Rostov-on-Don, Verkhnyaya Pyshma, Krasnoyarsk, Kazan, Naberezhnye Chelny, Murmansk, Vsevolozhsk, Yaroslavl, Kemerovo, Ryazan, Saratov, Tula, Usinsk, Orenburg, Novotroitsk, Krasnodar, Ulyanovsk, Izhevsk, Irkutsk, Tyumen, Voronezh, Cheboksary, Neftekamsk, Veliky Novgorod, Tver, Astrakhan, Novomoskovsk, Tomsk, Prokopyevsk, Penza, Urai, Pervouralsk , Belgorod, Kursk, Taganrog, Vladimir, Neftegorsk, Kirov, Bryansk, Smolensk, Saransk, Ulan-Ude, Vladivostok, Vorkuta, Podolsk, Krasnogorsk, Novouralsk, Novorossiysk, Khabarovsk, Zheleznogorsk, Kostroma, Zelenogorsk, Tambov, Stavropol, Svetogorsk, Zhigulevsk , Arkhangelsk and other cities of the Russian Federation.

In Ukraine there is an established delivery system to the following cities: Kiev, Kharkov, Dnepr (Dnepropetrovsk), Odessa, Donetsk, Lvov, Zaporozhye, Nikolaev, Lugansk, Vinnitsa, Simferopol, Kherson, Poltava, Chernigov, Cherkassy, ​​Sumy, Zhitomir, Kirovograd, Khmelnitsky , Rivne, Chernivtsi, Ternopil, Ivano-Frankivsk, Lutsk, Uzhgorod and other cities of Ukraine.

In Belarus there is an established delivery system to the following cities: Minsk, Vitebsk, Mogilev, Gomel, Mozyr, Brest, Lida, Pinsk, Orsha, Polotsk, Grodno, Zhodino, Molodechno and other cities of the Republic of Belarus.

In Kazakhstan, there is an established delivery system to the following cities: Astana, Almaty, Ekibastuz, Pavlodar, Aktobe, Karaganda, Uralsk, Aktau, Atyrau, Arkalyk, Balkhash, Zhezkazgan, Kokshetau, Kostanay, Taraz, Shymkent, Kyzylorda, Lisakovsk, Shakhtinsk, Petropavlovsk, Rider, Rudny, Semey, Taldykorgan, Temirtau, Ust-Kamenogorsk and other cities of the Republic of Kazakhstan.

Manufacturer TM "Infrakar" is a manufacturer of multifunctional devices such as a gas analyzer and a smoke meter.

If the technical description does not contain the information you need about the device on the website, you can always contact us for help. Our qualified managers will clarify for you the technical characteristics of the device from its technical documentation: operating instructions, passport, form, operating manual, diagrams. If necessary, we will take photographs of the device, stand or device you are interested in.

You can leave reviews on a device, meter, device, indicator or product purchased from us. If you agree, your review will be published on the website without providing contact information.

Descriptions of the devices are taken from technical documentation or technical literature. Most photos of products are taken directly by our specialists before shipment of the goods. The description of the device provides the main technical characteristics of the devices: rating, measurement range, accuracy class, scale, supply voltage, dimensions (size), weight. If on the website you see a discrepancy between the name of the device (model) and the technical specifications, photos or attached documents - please let us know - you will receive a useful gift along with the purchased device.

If necessary, you can check the total weight and dimensions or the size of an individual part of the meter in our service center. If necessary, our engineers will help you choose a complete analogue or the most suitable replacement for the device you are interested in. All analogues and replacements will be tested in one of our laboratories to ensure full compliance with your requirements.

Our company carries out repairs and service maintenance of measuring equipment from more than 75 different manufacturing plants of the former USSR and CIS. We also carry out the following metrological procedures: calibration, calibration, graduation, testing of measuring equipment.

Devices are supplied to the following countries: Azerbaijan (Baku), Armenia (Yerevan), Kyrgyzstan (Bishkek), Moldova (Chisinau), Tajikistan (Dushanbe), Turkmenistan (Ashgabat), Uzbekistan (Tashkent), Lithuania (Vilnius), Latvia (Riga) ), Estonia (Tallinn), Georgia (Tbilisi).

Zapadpribor LLC offers a huge selection of measuring equipment with the best price-quality ratio. So that you can buy devices inexpensively, we monitor competitors’ prices and are always ready to offer a lower price. We sell only quality products at the best prices. On our website you can cheaply buy both the latest new products and time-tested devices from the best manufacturers.

The site constantly has a promotion “Buy at the best price” - if on another Internet resource the product presented on our site has a lower price, then we will sell it to you even cheaper! Buyers are also given an additional discount for leaving reviews or photographs of the use of our products.

The price list does not contain the entire range of products offered. You can find out prices for goods not included in the price list by contacting the managers. You can also get detailed information from our managers on how to cheaply and profitably buy measuring instruments wholesale and retail. Telephone and email for consultations on purchasing, delivery or receiving a discount are listed above the product description. We have the most qualified employees, high-quality equipment and competitive prices.

Zapadpribor LLC is an official dealer of measuring equipment manufacturers. Our goal is to sell high quality products with the best price offers and service for our customers. Our company can not only sell the device you need, but also offer additional services for its verification, repair and installation. To ensure that you have a pleasant experience after purchasing on our website, we have provided special guaranteed gifts for the most popular products.

The META plant is a manufacturer of the most reliable instruments for technical inspection. The STM brake tester is produced at this plant.

If you can repair the device yourself, then our engineers can provide you with a complete set of necessary technical documentation: electrical diagram, maintenance, manual, FO, PS. We also have an extensive database of technical and metrological documents: technical conditions (TS), technical specifications (TOR), GOST, industry standard (OST), verification methodology, certification methodology, verification scheme for more than 3,500 types of measuring equipment from the manufacturer of this equipment. From the site you can download all the necessary software (program, driver) required for the operation of the purchased device.

We also have a library of regulatory documents that are related to our field of activity: law, code, resolution, decree, temporary regulation.

At the customer's request, verification or metrological certification is provided for each measuring device. Our employees can represent your interests in such metrological organizations as Rostest (Rosstandart), Gosstandart, Gospotrebstandart, CLIT, OGMetr.

Sometimes customers may enter the name of our company incorrectly - for example, zapadpribor, zapadprilad, zapadpribor, zapadprilad, zahidpribor, zahidpribor, zahidpribor, zahidprilad, zahidpribor, zahidpribor, zahidprilad. That's right - the west device.

LLC "Zapadpribor" is a supplier of ammeters, voltmeters, wattmeters, frequency meters, phase meters, shunts and other instruments from such measuring equipment manufacturers as: PA "Electrotochpribor" (M2044, M2051), Omsk; OJSC Instrument-Making Plant Vibrator (M1611, Ts1611), St. Petersburg; OJSC Krasnodar ZIP (E365, E377, E378), LLC ZIP-Partner (Ts301, Ts302, Ts300) and LLC ZIP Yurimov (M381, Ts33), Krasnodar; JSC “VZEP” (“Vitebsk Plant of Electrical Measuring Instruments”) (E8030, E8021), Vitebsk; JSC "Electropribor" (M42300, M42301, M42303, M42304, M42305, M42306), Cheboksary; JSC "Electroizmeritel" (Ts4342, Ts4352, Ts4353) Zhitomir; PJSC "Uman plant "Megommeter" (F4102, F4103, F4104, M4100), Uman.

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

If we compare the currents in the primary and secondary windings, it turns out that the current in the primary winding circuit is five times less than in the secondary winding. This suggests the idea of ​​placing a welding current regulator in the primary winding of the transformer, using thyristors for this purpose. In Fig. Figure 20 shows a diagram of the welding current regulator using thyristors. With extreme simplicity and accessibility of the element base, this regulator is easy to operate and does not require configuration.

Rice. 1 Schematic diagram of the current regulator of the welding transformer:
VT1, VT2 -P416

VS1, VS2 - E122-25-3

C1, C2 - 0.1 µF 400 V

R5, R6 - 1 kOhm

Power regulation occurs when the primary winding of the welding transformer is periodically turned off for a fixed period of time at each half-cycle of the current. The average current value decreases. The main elements of the regulator (thyristors) are connected counter 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 resistor R7, you can regulate 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. 2)

Rice. 2 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 resistor R7, and the cathodes should be connected to resistors R3 and R4. If the regulator is assembled using dinistors, then it is better to use devices of the KN102A type.

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

The design of a convenient and reliable DC regulator is proposed. Its voltage range is from 0 to 0.86 U2, which allows you to use this valuable device for various purposes. For example, for charging high-capacity batteries, powering electric heating elements, and most importantly - for welding with both a conventional electrode and stainless steel, with smooth current regulation.

Schematic diagram of a DC regulator.

A graph explaining the operation of a power unit made according to a single-phase bridge asymmetrical circuit (U2 is the voltage coming from the secondary winding of the welding transformer, alpha is the opening phase of the thyristor, t is time).

The regulator can be connected to any welding transformer with secondary winding voltage U2=50. 90V. The proposed design is very compact. The overall dimensions do not exceed the dimensions of a conventional unregulated bridge rectifier. for welding with direct current.

The regulator circuit consists of two blocks: control A and power B. Moreover, the first is nothing more than a phase-pulse generator. It is made on the basis of an analogue of a unijunction transistor, assembled from two semiconductor devices of n-p-n and p-n-p types. Using variable resistor R2, the direct current of the structure is regulated.

Depending on the position of the R2 slider, capacitor C1 is charged here to 6.9 V at different rates. When this voltage is exceeded, the transistors open sharply. And C1 begins to discharge through them and the winding of the pulse transformer T1.

The thyristor, to the anode of which a positive half-wave approaches (the pulse is transmitted through the secondary windings), opens.

As a pulse one, you can use industrial three-winding TI-3, TI-4, TI-5 with a transformation ratio of 1:1:1. And not only these types. For example, good results are obtained by using two two-winding transformers TI-1 with a series connection of the primary windings.

Moreover, all of the above types of TIs make it possible to isolate the pulse generator from the control electrodes of the thyristors.

There is only one “but”. The pulse power in the secondary windings of the TI is not sufficient to turn on the corresponding thyristors in the second (see diagram), power block B. The way out of this “conflict”9raquo; The situation was found to be elementary. To turn on the powerful ones, low-power thyristors with high sensitivity to the control electrode are used.

Power block B is made according to a single-phase bridge asymmetrical circuit. That is, the thyristors work here in one phase. And the arms on VD6 and VD7 work as a buffer diode during welding.

Installation? It can also be mounted, based directly on a pulse transformer and other relatively “large-sized”9raquo; elements of the circuit. Moreover, the radio components connected to this design are, as they say, minimum-minimorum.

The device starts working immediately, without any adjustments. Get yourself one - you won't regret it.

A. CHERNOV, Saratov. Modeler-constructor 1994 No. 9.

Category: “Electronic homemade products”

Simple electronic welding current regulator, diagram

Often you have to weld metal of different thicknesses and use electrodes of different diameters, and in order for the welding to be high-quality, it is necessary to adjust the welding current so that the seam lies evenly and the metal does not splash. But, regulating the current of the secondary winding of a welding transformer is quite problematic, because it can reach up to 180-250A.

As an option, nichrome spirals are used to regulate the welding current, including them in series in the circuit of the primary or secondary winding of the welding transformer, or chokes. It is inconvenient to regulate the current in this way, and the regulator itself is cumbersome. But there is another way out - to make an electronic welding current regulator that would regulate the current in the primary winding of the welding machine.

The welding current regulator for a homemade welding machine is also very useful in cases where you have to weld metal in places where the power grid is weak, for example in villages. As a rule, they limit the current consumption for each house by installing an input circuit breaker of 16 A, i.e. You cannot turn on a load of more than 3.5 kW. A good welding machine, welding with electrodes with a diameter of 4-5 mm, consumes 6-7, or even 8 kW.

Therefore, we reduced the welding current and at the same time reduced the current consumption of the welding machine, thus investing in those 3.5 kW and “C” welding what you need.

Here is a simple circuit of such a regulator with 2 thyristors and it has a minimum of non-scarce parts. It can be done with 1 triac, but, as practice has shown, it is more reliable with thyristors.

The welding current regulator works as follows: a regulator is connected in series to the primary winding circuit, which consists of two controlled thyristors VS1 and VS2 (T122-25-3, or E122-25-3), for each half-wave. The opening moment of the thyristors is determined by the RC circuit (R7, C1, C2). By changing the resistance R7, we change the opening moment of the thyristors and thereby change the current in the primary winding of the transformer, and therefore the current in the secondary winding also changes.

Transistors can be used of the old type - P416, GT308, their lekko can be found in old receivers or televisions, and capacitors are used like MBT or MBM for an operating voltage of at least 400 V.

Transistors VT1, VT2 and resistors R5, R6, connected as shown in the diagram, are an analogue of dinistors and in this embodiment they work better than dinistors, but if you really want, instead of VT1, R5 and VT2, R6 you can put ordinary dinistors - type KN102A.

When assembling and setting up the welding current regulator, do not forget that control occurs under a voltage of 220V. Therefore, in order to prevent electric shock, all radio elements, as well as thyristor heat sinks, must be insulated from the housing!

In practice, the above electronic welding current regulator has proven itself to be excellent.
The basis was taken from the magazine Radioamator. - 2000. - No. 5 “Do-it-yourself welding transformer.”

Recently I talked with my teacher at the university, and to my misfortune, I revealed my amateur radio talents. In general, the conversation ended with the fact that I undertook to assemble a man a thyristor rectifier with a smooth current regulator for his welding “donut”. Why is this necessary? The fact is that alternating voltage cannot be welded with special electrodes designed for constant use, and given that welding electrodes come in different thicknesses (most often from 2 to 6 mm), the current value must be proportionally changed.

When choosing a welding regulator circuit, I followed the advice of -igRomana- and settled on a fairly simple regulator, where the current is changed by applying pulses to the control electrodes, generated by an analogue of a powerful dinistor, assembled on a KU201 thyristor and a KS156 zener diode. See the diagram below:

Despite the fact that an additional winding with a voltage of 30 V was required, I decided to make it simpler, and in order not to touch the welding transformer itself, I installed a small additional one of 40 watts. Thus, the attachment-regulator has become completely autonomous - it can be connected to any welding transformer. I assembled the remaining parts of the current regulator on a small board made of foil PCB, the size of a pack of cigarettes.

As a base I chose a piece of vinyl plastic, onto which I screwed the TC160 thyristors themselves with radiators. Since there were no powerful diodes at hand, we had to force two thyristors to perform their function.

It is also attached to a common base. Terminals are used to input the 220 V network; the input voltage from the welding transformer is supplied to the thyristors through M12 screws. We remove the constant welding current from the same screws.

The welding machine is assembled, it's time for testing. We apply a variable from the torus to the regulator and measure the voltage at the output - it almost does not change. And it shouldn’t, since accurate voltage control requires at least a small load. It could be a simple 127 (or 220 V) incandescent lamp. Now, even without any testers, you can see a change in the brightness of the lamp, depending on the position of the resistor-regulator slider.

So it’s clear why the second trimming resistor is indicated in the diagram - it limits the maximum value of the current that is supplied to the pulse shaper. Without it, the output from half the engine already reaches the maximum possible value, which makes the adjustment not smooth enough.

To correctly set the range of current changes, you need to set the main regulator to the maximum current (minimum resistance), and the tuning regulator (100 Ohms) to gradually reduce the resistance until its further decrease leads to an increase in the welding current. Capture this moment.

Now the tests themselves, so to speak, on hardware. As intended, the current is normally regulated from zero to maximum, but the output is not constant, but rather a pulsed direct current. In short, the DC electrode did not cook and still does not cook properly.

You will have to add a block of capacitors. To do this, we found 5 pieces of excellent electrolytes for 2200 uF 100 V. By connecting them with two copper strips in parallel, I got a battery like this.

We carry out tests again - the DC electrode seems to have started to cook, but a bad defect has been discovered: at the moment the electrode touches, a micro-explosion and sticking occurs - this is the capacitors being discharged. Obviously you can't do without a throttle.

And then luck did not leave us with the teacher - in the store there was simply an excellent DR-1S choke, wound with a 2x4 mm copper busbar on the W-iron and weighing 16 kg.

It's a completely different matter! Now there is almost no sticking and the DC electrode cooks smoothly and efficiently. And at the moment of contact there is not a micro-explosion, but a kind of light hissing. In short, everyone is happy - the teacher has an excellent welding machine, and I am relieved of the headache with an archetypal object that has nothing to do with electronics :)

How to make a simple current regulator for a welding transformer

An important design feature of any welding machine is the ability to adjust the operating current. In industrial devices, different methods of current regulation are used: shunting using chokes of various types, changing the magnetic flux due to the mobility of the windings or magnetic shunting, using stores of active ballast resistances and rheostats. The disadvantages of such adjustment include the complexity of the design, the bulkiness of the resistances, their strong heating during operation, and inconvenience when switching.

The best option is to make it with taps while winding the secondary winding and, by switching the number of turns, change the current. However, this method can be used to adjust the current, but not to regulate it over a wide range. In addition, adjusting the current in the secondary circuit of a welding transformer is associated with certain problems.

Thus, significant currents pass through the regulating device, which leads to its bulkiness, and for the secondary circuit it is almost impossible to select such powerful standard switches that they can withstand a current of up to 200 A. Another thing is the primary winding circuit, where the currents are five times less.

After a long search through trial and error, the optimal solution to the problem was found - the well-known thyristor regulator, the circuit of which is shown in Fig. 1.

With the utmost simplicity and accessibility of the element base, it is easy to operate, does not require settings and has proven itself in operation - it works just like a “clock”.

Power regulation occurs when the primary winding of the welding transformer is periodically turned off for a fixed period of time at each half-cycle of the current. The average current value decreases.

The main elements of the regulator (thyristors) are connected counter 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. After the start of the next half-cycle of the alternating current, the thyristor closes and a new cycle of charging the capacitors begins, but in reverse polarity. Now the second transistor opens, and the second thyristor reconnects the load to the network.

By changing the resistance of the variable resistor R7, you can regulate 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. The anodes of the dinistors should be connected to the extreme terminals of resistor R7, and the cathodes should be connected to resistors R3 and R4. If the regulator is assembled using dinistors, then it is better to use devices of the KN102A type.

Variable resistor type SP-2, the rest type MLT. Capacitors of the MBM or MBT type for an operating voltage of at least 400 V.

A correctly assembled regulator does not require adjustment. You just need to make sure that the transistors are stable in avalanche mode (or that the dinistors are switched on stably).

Attention! The device has a galvanic connection to the network. All elements, including thyristor heat sinks, must be isolated from the housing.

j&;electrician Ino - electrical engineering and electronics, home automation, l&;articles about the construction and repair of home electrical wiring, sockets and switches, wires and cables, and&;sources l&;veta, interesting acts and much more for electricians and home builders.

Information and training materials for other electricians.

Keys, examples and technical solutions, overviews of interesting electrical innovations.

The information on the site j&;electrician is provided in informational and educational documents. The administration of the site is not responsible for the use of this information. Sai can l&;obtain materials 12+

Reproduction of l&;ite k&;materials is prohibited.

Assembling homemade DC welding machines

• Welding machine: arc characteristic
• Dynamic response
• Possible details and calculations
• Schematic diagram
• Welding circuit operation:
• Design of transformer and chokes
• Device design
  • Parts and materials of the welding device:
  • Assembly tools

To make homemade DC welders, you will need a high-power power source that converts the rated voltage of a conventional single-phase network and provides a constant value (in amperes) of the appropriate current to directly create and maintain a normal electric arc.

Schemes of a homemade DC welding machine.

The high-power power source is a circuit consisting of the following components:

• rectifier;
• inverters;
• current and voltage transformer;
• current and voltage regulators that improve the quality characteristics of the electric arc (thyristors, triacs);
• auxiliary devices.

In fact, based on homemade circuits, the source of the electric arc was and remains a transformer, even if you do not use auxiliary components and circuits of various control units.

Homemade device: block diagram

Schematic diagram of the power supply of the welding machine.

The power supply is inserted into a corresponding box made of plastic or metal. It is supplied with the necessary elements: connecting connectors, various switches, terminals and regulators. The welding machine can be equipped with carrying handles and wheels.

Such a design of fairly good quality welding can be done independently. The main secret of such a device is a minimal understanding of the welding process, the choice of material, as well as skill and patience in the manufacture of this device.

But to assemble the device yourself, you must at least slightly understand and study the basic skills, the moment of occurrence and combustion of the electric arc and the theory of electrode melting. Know the characteristics of welding transformers and their magnetic circuits.

Return to contents

Homemade device: transformer

The basis of any welding device circuit is a transformer that reduces the normal voltage (from 220 V to 45-80 V). It operates in a special arc mode with maximum power. Such transformers simply must withstand very high currents with a nominal value of about 200 A. Their characteristics must be consistent, the I-V characteristic of the transformer must certainly fully comply with special requirements, otherwise it cannot be used for arc welding mode.

Welding machines (their designs) vary greatly. The variety of homemade welding transformers is enormous, because the designs contain a lot of truly unique solutions. In addition, homemade transformers are very simple: they do not contain additional devices designed to directly regulate the current of the structure that flows:

Design of a homemade semi-automatic welding machine.

• using highly specialized regulators;
• by switching a certain number of turns of coils.

The transformer mainly consists of the following elements:

1. The magnetic core is metal. It is performed by a set of plates made of transformer steel.
2. Windings: primary (network) and secondary (working). They come with leads for adjustment (by switching) or for device circuitry.

When calculating a transformer for the required current, welding is carried out, as a rule, immediately from the working winding, without attaching circuits and various limiting and adjustment elements. The primary winding must be made with terminals and taps. They serve to increase or decrease the current (for example, to adjust the transformer at low network voltage).

The main part of any transformer is its magnetic circuit. In the manufacture of home-made designs, magnetic cores are used from decommissioned stators of electric motors, old television and power transformers. Therefore, there is a huge variety of different magnetic circuits developed by folk craftsmen for such devices.

Welding transformer based on the widely used LATR2 (a).

• magnetic circuit dimensions;
• windings – number of turns;
• input-output voltage level;
• I p – current consumed;
• I max – maximum output current.

Additional characteristics simply cannot be assessed or measured at home, even with the help of instruments. But it is precisely they that determine the suitability of the device’s transformer for forming a high-quality seam when powered in manual welding mode.

This directly depends on how the transformer “holds current” and is called the external current-voltage characteristic (IV-voltage characteristic) of the supply.

VVC – dependence of the potentials (U) on the connectors and the welding current, which varies from the load properties of the transformer and from the electric arc.

For manual welding, only a steeply falling characteristic is used, while in automatic welding machines a flat and rigid characteristic is used.