Winding a toroidal transformer through the eyes of a practitioner. Finishing and fasteners
This article does not claim to be the best-seller of popular science literature, but rather a guide for beginners. The article describes the winding process itself, and not its calculation.
Sooner or later, in the practice of every amateur, the question arises of what to power this or that device. The most popular power of the ULF is 2100 or 2200.
Therefore, the best option is a “donut” for 150 watts of overall power, in the first case one is needed for 2 channels, in the other a couple for double mono.
The toroidal transformer has the best size-to-power ratio, high efficiency, and minimal interference. That is why audiophiles love them so much. Consider the winding process of this type of transformer in more detail.
The main things that the person who winds the transformer should know and most importantly understand:
- wire length (number of turns) is the voltage;
- the cross section of the conductor is the current by which it can be loaded;
- if the number of turns in the primary circuit is small, then this is excess heating of the wire;
- if the overall power is insufficient (consumed more than possible), it is again warm;
- overheating of the transformer leads to a decrease in reliability.
So, what is needed for winding:
- Transformer iron in the form of a torus (hereinafter I will write where to get it);
- Varnish pipe (a winding wire is needed on the transformer winding);
- Masking tape (paper);
- PVA glue;
- Fabric tape or keeper;
- Pieces of wire in isolation;
- Last but not least, desire.
I will not talk about how to calculate the power of iron for this. There are already a lot of articles. The calculation of power is difficult from a practical point of view, since the grade of steel is not known, the quality of its production. Therefore, two cores with the same overall mass have different parameters. Consider an example of core winding on an already “spent” core.
One of the most easily delivered cores, the quality of which is worthy of attention. Is the core of the Soviet stabilizer "Ukraine-2" (sn-315). At one time, there were a lot of them burned, and on the market you can get such a device for 20 UAH. We are interested in the torus.
This bagel is wound with aluminum varnish duct, we reel it mercilessly (or bite it), we need a core (carefully so as not to damage the core). The aluminum wire can be used for other purposes (twist brooms or wires), or as in my case, I remelted it for other purposes (I make radiators).
After winding, a beautiful core with dimensions of 96-54-32 mm, respectively, outer, inner diameter and height, is obtained. Below is an example of such a core (Fig. 1). The overall power of such a core is at least 120 watts (tested in practice).
Before winding, it is necessary to prepare the iron for winding. If you look at the corners of the transformer, then take them away at an angle of 90 degrees, the wire will bend at these points and the lacquer will peel off, so that it would not be necessary to process the corners with a file by rounding them as much as possible (I understand that laziness is necessary). The minimum radius of the circle is 3mm. In Fig.
Figure 1 shows that the corners have already been machined, and the torus is ready for winding. A little trick, when processing corners with a file, it is necessary to avoid licking steel, so that the layers between themselves remain not closed! To do this, file movements along the direction of the transformer tape.
After processing, I recommend viewing the angles to the closure of the layers and finalizing them with a small file.
In order to isolate the core from the winding, it is necessary to isolate it with a TISSUE insulating tape (or with a paraffin wax wax impregnated keeper). It is better to use electrical tape from a width of about 25mm (Fig. 2), then there will be a maximum metal coating in one layer, which saves space in the window. The end of the winding is not sealed (read on).
After these operations, the core is ready for winding and we move on to the next step.
I call an electrical conductor an electrical conductor whose insulation is made of varnish (on a cultural winding or winding wire). There are different brands of PEV, PEV-2, PET-155 and others. I recommend using PEV-2, a saturated orange color.
The wire is also very well-behaved very dark in appearance (PEL), the color of rotten cherry, this one has a thick layer of insulation, which allows it to be used for high voltage transformers (more than 500V).
For example, a PEV-2 wire with a diameter of 1.6 mm has an insulation thickness of about 0.06-0.07 mm and a "black" 0.1-0.11 mm.
Winding toroidal transformer
To convert current, various types of special devices are used. The toroidal transformer CCI for the welding machine and other devices, you can wrap it yourself at home, it is an ideal energy converter.
The first bipolar transformer was made by Faraday, and according to the data, it was just a toroidal device.
A toroidal autotransformer (Stihl, TM2, TTS4 brand) is a device designed to convert alternating current from one voltage to another. They are used in various linear installations.
This electromagnetic device can be single-phase and three-phase. Structurally consists of:
- A metal disk made of rolled magnetic steel for transformers;
- Rubber gasket;
- Conclusions of the primary winding;
- Secondary winding;
- Insulation between windings;
- Shielding winding;
- An additional layer between the primary winding and the shielding;
- Primary winding;
- Core insulation coating;
- Toroidal core;
- Covering isolation.
A magnetic circuit is used to connect the windings.
This type of converters can be classified by purpose, cooling, type of magnetic circuit, windings. By appointment, there is a pulse, power, frequency converter (TST, TNT, TTS, TT-3). On cooling. air and oil (OST, OSM, TM). By the number of windings. double-winding or more.
Photo. the principle of operation of the transformer
A device of this type is used in various audio and video installations, stabilizers, lighting systems. The main difference between this design and other devices is the number of windings and the shape of the core.
Physicists believe that the ring shape is the perfect execution of the anchor. In this case, the winding of the toroidal transducer is uniform, as is the distribution of heat.
Due to this arrangement of coils, the converter cools quickly and even with intensive work does not need to use coolers.
Photo. toroidal ring converter
Advantages of a toroidal transformer:
- Small dimensions;
- The output on the torus is very strong;
- The windings have a small length, and as a result, reduced resistance and increased efficiency. But also because of this, a certain sound background is heard during operation;
- Excellent energy saving features;
- Simplicity in independent installation.
The converter is used as a network stabilizer, a charger, as a power supply unit for halogen lamps, a VLF tube amplifier.
Photo. ready TPN25
Video: toroidal transformer assignment
Principle of operation
The simplest toroidal transformer consists of two windings on a ring and a steel core. The primary winding is connected to source of electric current, and the secondary to a consumer of electricity.
Due to the magnetic circuit, individual windings are connected to each other and their inductive coupling is amplified. When you turn on the power in the primary winding creates an alternating magnetic flux.
Interlocking with individual windings, this flow creates an electromagnetic force in them, which depends on the number of turns of the winding. If you change the number of windings, then you can make a transformer to convert any voltage.
Photo. The principle of action
Also, converters of this type are lowering and raising. The toroidal step-down transformer has a high voltage at the terminals of the secondary winding and a low voltage at the primary. Boost on the contrary. In addition, the windings can be of higher voltage or lower, depending on the characteristics of the network.
How to do
The manufacture of a toroidal transformer is possible even for young electricians. Winding and calculation are not complicated. We suggest you consider how to properly wind a toroidal magnetic circuit for a semiautomatic device:
Given that 1 turn transfers 0.84 Volts, the winding circuit of a toroidal transformer is performed according to this principle:
So you can easily make your own toroidal transformer 220 by 24 volts. The described circuit can be connected both to arc welding and to semi-automatic.
The parameters are calculated based on the cross section of the wire, the number of turns, the size of the ring. The characteristics of this device allow for stepwise adjustment.
Among the advantages of the assembly principle: simplicity and accessibility. Among the shortcomings: a lot of weight.
You can buy a toroidal transformer HBL-200 in any city of the Russian Federation and the CIS countries. It is used for various audio equipment. Consider how much the converter costs.
Winding toroidal transformer
Home »Lighting» Transformers »Winding toroidal transformer
A variety of devices are used to convert current today. A toroidal transformer is the most common device that is used not only for a welding machine. Winding a toroidal transformer is considered a popular service.
To wind a toroidal transformer at home, you should read our instructions.
This wonderful transformer was made by Faraday. A toroidal autotransformer is a special device that is designed to convert AC. You can use them in a variety of linear installations. This electromagnetic device can be single-phase and three-phase.
In this photo you can see that the design consists of the following elements:
- A metal disk that is made of rolled magnetic steel.
- Special rubber pads.
- The conclusions of the primary winding.
- Secondary winding.
- Insulation, which is located between the windings.
- Shielding winding.
- An additional layer, which is located between the primary and the shielding winding.
- Primary winding.
- Core insulation.
- Toroidal core.
- Layer of cover insulation.
To connect the windings, the manufacturer uses a magnetic circuit. This type of converter qualifies for: purpose, cooling, and type of magnetic circuit. By appointment, it can be divided into a pulse, power and frequency converter. For cooling transformers, air or oil. If you are interested, then you can read about the toroidal transformer.
A device of this type can be used in stabilizers or cooling systems. The main difference in the design will be the number of windings that the transformer contains.
The ring shape is considered the most common. In this case, the winding of the toroidal converter is uniform.
Thanks to this arrangement of coils, the converter cools quickly and will not need to use coolers.
Advantages of a toroidal transformer
If you plan to use a toroidal transformer, then remember that it can have several advantages:
- The design has small dimensions.
- The signal on the torus is considered quite strong.
- Windings may be short. But because of this, when working, you can hear a certain background.
- Simplicity in independent installation.
The converter can be used as a mains transformer, charger or block for halogen lamps. If necessary, you can read about the principle of operation of a current transformer.
If you want to receive detailed information on how to make a toroidal transformer with your own hands, then you need to watch the video below:
The manufacture of a toroidal transformer can be performed even by a young electrician. Winding is nothing complicated. Here is an instruction that will help you learn how to wind a toroidal magnetic circuit for a semiautomatic device:
- To wind the transformer on a ferrite core, you need to use a special machine. It allows you to significantly speed up the work and at the same time you can easily reduce the likelihood of a jump of iron. It can be performed by the type of clamp for wrapping the wire.
- Latras that are needed for winding should have the same size. When winding, you need to make sure that there is no free space between the turns. If the power transformer will have small gaps, then they can be filled with iron sheets from another transformer.
- After winding iron, it is necessary to weld special conclusions. To weld the product, 2 or 3 welding points will be sufficient.
- Now you need to grease the ends of the magnetic circuit with epoxy glue. If necessary, the edges can be rounded.
- You should wrap insulation over the amplifier. To perform the winding, you can use a sheet of cardboard. You can attach it using masking tape. Repeat this action is necessary throughout the cardboard.
- Now you can wind the electrical tape, which is made of textile. You can also use masking tape on top of the layer.
- The last stage includes winding the wire of the selected cross section. You can calculate the number of turns using a special program. After wrapping, the product must be varnished with NC.
- The insulation for the toroidal transformer must be made of varnish or textile tape. This winding is called secondary and should also be varnished. This action should be continued until the required level of turns.
- The wire for the secondary winding usually has a large cross section. If a mains transformer is needed for arc welding, then at the end you should add the required number of turns.
One turn is capable of carrying 0.84 volts. The winding circuit of a toroidal transformer is as follows:
So you can easily independently make a toroidal transformer 220 by 24 volts. You can easily connect this circuit, both for arc and semi-automatic welding.
All parameters must be calculated based on the cross section of the wire. The characteristics of the device also allow for stepwise adjustment.
Among its advantages can be found quite high performance and availability.
You can buy a toroidal transformer HBL-200 in almost any city. In the photo below you can see the cost of the converter:
We hope that our information will be useful and you will be able to correctly wind the toroidal transformer. As you can see, winding a toroidal transformer does not take much time.
How to wind a toroidal transformer with your own hands
HOW TO WIND A TOROIDAL TRANSFORMER
The winding technology and the insulation method is actually very simple and does not in any way imply any winding, nor varnish, or anything else.
The fact is that with any winding of the transformer core with varnished cloth or other insulators, the inner window of the TOPA instantly fills, since on the outer side one layer is obtained, and on the inner 5-10 layers, even uneven.
For a long time I was going to write an article about the method of high-quality winding of toroidal transformers. This is quite a long time to explain and better shown in the photo.
over, after winding, the windings do not turn into a wheel, and the transformer itself does not become egg-shaped and the wire consumption is minimal. In view of all this and the efficiency of the transformer is maximum. And what comes of this, you can see in my amplifier.
Immediately make a reservation, we are talking about powerful toroidal transformers. Overall power, of which more than 500 watts. Which are wound with wires from 1 to 3 mm. Naturally turn to turn. And, as a rule, the network winding of which lies in the aisles from 100 to 400 turns, in total, that is, 0.5-2 turns per volt. To wind less powerful transformers in this way is troublesome, but you can if you wish.
What is needed for winding: 1) It is necessary to make a stand for winding a toroid, this is done very simply. We take a square piece of chipboard or plywood 10-15 mm thick. With dimensions of 200X200mm, we also need two wooden blocks 200 mm long and with a square 20X20mm. We need to either stick these two bars in the center of our site, parallel to each other, at a distance between them of 100 mm. Better yet, fasten these bars to the site with screws, but with countersunk heads and heads, drown in plywood otherwise they will scratch the table. Now if you put a toroid on this stand, it will stand firmly and steadily. 2) I need a shuttle, I cut out the shuttle from plexiglass 5-mm thick. Width is usually 30-40mm. 300-400mm long. I do not make end cuts in a semicircle, but in a semicircle and treat them with a file so that the insulation of the wire does not deteriorate and even glue the tape with one or two strips again to protect the wire. We wind the wire around the shuttle, it’s okay if the wire isn’t enough, you can carefully solder the wire and wind it on. But it’s better to calculate, so that there would be enough wire. 3) Now we need material for insulation between the layers, it is very simple to find thin cardboard (packaging), for example, I use speaker boxes for cars. The main thing is that it was not thick, but not thin material. the thickness of the cardboard, somewhere 0.5 mm. If it will be glossy on one side, then this is also good.
4) We also need strings of thick 10-20 number. But at worst, you can also number 40. The winding itself is conducted from itself to the right.
And now the most important thing is the manufacture of the insulating gaskets themselves between the layers. We need a caliper with sharp ends. We measure the outer diameter of our torus, add 20mm. (for overlap) and divide in half. For example, the outer diameter of the torus is 150 mm. 20 mm. = 170 mm. 170mm. / 2 = 85 mm.
We expose the 85mm bar. and fix it with a screw. We will use the bar itself as a compass for drawing circles on cardboard.
Why precisely with a caliper, and not with an ordinary compass, which is both easier and more convenient? And everything is very simple, when we draw the sharp and strong end of the barbell on cardboard, then there will be a sagging groove on the cardboard and it will help us.
This furrow is very useful for the convenience of bending the inner dissected circumference of our gaskets. In general, you yourself will understand that a caliper is better than a convenient compass.
And so we draw the outer circle on the cardboard and cut it out with scissors, in principle, the outer circle can be drawn with an ordinary compass.
Next, measure the inner diameter of the torus, add nothing, do not reduce, but simply divide in half. For example, the diameter is 60mm. / 2 = 30 mm. We expose, namely, the caliper, 30mm. fix it with a screw and draw the inner diameter on the cardboard.
Video: How To Wind A Line Into A Stihl Trimmer Coil
Next, we take a pencil and a ruler and work on the inner circle, first draw a cross, that is, divide the circle into 4 parts, then into 8 parts, if the inner diameter of the TOP is more than 60 mm. it’s also in 16 parts. Next, we draw another circle with an ordinary compass, which is half as much as the inside, that is, we extend the compass by 15 mm.
And now we need an even piece, plywood or chipboard on which, we put our cardboard blank for cutting with the end of a sharp scalpel or knife, applied with a pencil of our parts. You need to cut in a circle from the outer edge of the circle to the center point, not further, otherwise the cardboard will bulge. You need to cut through the cardboard.
Then with scissors we cut out the inner circle drawn by us with an ordinary compass. The resulting slices are bent perpendicular to the workpiece. It is clear that such blanks are needed for each layer in two pieces, each time the diameters are measured again, since their value changes from layer to layer.
Next, measure the height of the torus and cut out two strips of cardboard of the same width. We insert one strip into the torus, so that the overlap would be no more than 10 mm. We wind the second strip with one layer on the outside of the torus with the same overlap. We put both round blanks on the ends of the torus, fasten with a thread in three or four places in a circle. And then we begin to wind.
The most dangerous places for breakdown are the corners of the circles of the TOPA external and especially internal. Therefore, if during winding we see that the wire may come into contact with the wire of the inner layer, especially along the inner corner of the circumference of the TOP. Then you need to put strips of the same cardboard 10 mm wide under the wire. and 20-30 mm long., where necessary.
On the outside, as a rule, you do not have to do this, since the outside of the workpiece is layered on the edge and protects the wire from short circuiting.
All marking and cutting of cardboard blanks is done on the matte side of the cardboard, glossy cardboard is not recommended on both sides.
Before you start to wind the torus, you need to wind two layers of electrical tape on the fingers on both the folds of the little finger and the fold of the index finger, otherwise there will be huge water corns.
Many are interested in how to calculate a toroidal transformer.
The fact is that the number of turns will depend on the quality of the iron, but an approximate calculation is done simply, as with a conventional transformer we only take a coefficient of 20-30.
Well, for example, we measure the height, it = 10 cm. We measure the wall thickness, it = 5 cm. 10 × 5 = 50 cm. 25/50 = 0.5 turns per 1 volt.
220 × 0.5 = 110 turns of the network winding.
Now we begin to wind the network winding of the transformer, after wrapping about 90 turns, we try to turn it on to the network, while measuring the open-circuit current.
It is not difficult to connect the tip of the wire directly to the shuttle. Gradually wrapping the wire, we bring the idling current to 50-100 mA and on this we stop winding, the obtained number of turns will be real.
Now we divide this real number by 220 and we get the real value of the number of turns per 1 volt. And in accordance with this figure, we calculate all the output windings. Keep in mind that when the transformer is connected to the mains, the initial instantaneous inrush current is very large. And in order not to burn the tester, you need to do this: connect the network cable through a closed toggle switch in parallel with the toggle switch, turn on the tester, turn on the plug in the socket and only then open the toggle switch to see the no-load current.
By the way, precisely because of the powerful primary inrush current, transformers with a power of more than 1 kW must be turned on using a soft-start circuit. over, this scheme is very simple.
Fedotov Alexey Gennadievich. (UA3VFS)
Website administration address: email@example.com
Winding toroidal transformer for UMZCH
To make a transformer yourself, you first need to determine the type of iron. The most common transformers are from W-shaped plates.
At the same time, transformers on toroidal iron (bagel made of iron tape) have less weight and dimensions in comparison with transformers on armored cores from Ш-shaped plates. Also, tori are distinguished by better winding cooling conditions and increased efficiency.
With a uniform distribution of the windings around the perimeter of the toroidal core, there is practically no scattering field and in most cases there is no need to shield the transformer. Although when building a quality amplifier, the screen should not be neglected.
In addition, even on the best iron with an induction of 15,000 Gs in a toroidal transformer, the magnetization current has the form of pulses with a peak factor of 5. 50. This is source of powerful interference with a fairly wide range. or less sinusoidal current x.x. becomes by induction less than 6000 Gs for steel 3410 and 8000.
9000 Gs for 3425. Reduced induction significantly increases the cost and makes the transformer heavier, which is extremely undesirable for serial equipment. However, to reduce interference in the audio power amplifier, it makes sense to reduce the induction in the transformer of the power supply. In this case, the rule works. "The less induction, the better."
It is very convenient to use a calculator to calculate the parameters of a toroidal transformer. It allows you to quickly calculate the parameters of the transformer, having a ready-made torus.
For Hi-End UMZCH, it is recommended that core induction from Russian (Soviet) iron not be selected more than 1.0 T. For imported iron (torus from an old UPS), 1.2 T is permissible.
In this case, low magnetic interference and minimal acoustic noise from the transformer will be obtained.
Before winding the toroidal transformer, it is necessary to prepare the selected core: first, remove the chamfer with a semicircular file from all the sharp edges of the donut, then circle the end of the torus with a pencil and cut cheeks out of thick paper (postcard), glue the cheeks on the sides of the torus, glue the outer and inner sides of the core with plain paper. Other core insulation options are possible. The main thing is to prevent the possible closure of the primary winding to the core of the transformer as a result of a possible forcing of the insulation and damage to the varnish of the winding wire on the sharp edges of the torus during winding.
For winding a toroidal transformer, I use a shuttle made of wood or textolite at the ends of which I make cuts in the form of a dovetail. The shuttle is easy to make from a wooden student ruler 20-30 cm long.
And so that it does not crack along when winding the winding wire on it, the “dovetail” is reinforced with paper tape (3-4 turns across). When winding manually, use PELSHO, PESHO wires. In extreme cases, it is possible to use the widespread PEV-2 or PETV-2 winding wire.
Suitable inter-winding and external insulation are fluoroplastic PET films with a thickness of 0.01-0.02 mm, lacquer fabric LSSS with a thickness of 0.06-0.12 mm or cambric tape, I used a fluoroplastic film.
After winding the estimated number of turns of the primary winding, it is desirable to measure the open circuit current of the transformer. To do this, connect the tester in series with the primary winding in ammeter mode. To avoid any emergency, you can turn on a 220 V bulb with a power of 40 watts in series with the primary device.
The light will be on if the number of turns is small. If the trance is wound correctly, then the filament should have a pink tint. The toroidal transformer has large inrush currents, at the time of starting the overload can reach 160 times.
Therefore, the start of the transformer must be done not through the tester, but with the help of a "jumper", which then opens and the current begins to flow through the tester.
To measure the open circuit current, I use the following circuit:
In series with the primary winding of the transformer, I turn on a 10 Ohm resistor, apply the mains voltage and measure the voltage drop on it. Accordingly, the open circuit current is I = U / R. In my case, 0.045 V / 10 Ohms = 0.0045 A. or 4.5 mA.
The idle current rate for each transformer is individual and usually does not exceed 50 mA at a voltage of 220 V. Here, the basic rule is “The lower the h.h. current, the better”, the more the idle current shape is more like a sine.
For a toroid in the power supply UMZCH current x.x.:
- 20-30 mA. "satisfactory",
- 10-20. "good"
- less than 10 mA. excellent.
To calculate the number of turns of the primary winding, with any available wire (in my case, MTF) I wind the secondary winding, applying the mains voltage to the primary winding, measure the voltage on the secondary winding.
I have a tester showing 0.581 V on 4 turns of the secondary. Accordingly, the number of turns of the primary winding will be: U network x N secondary / U secondary. At the time of measurement, the network was 230 V. In numbers, we get: 230 V x 4 turns / 0.581 V = 1583 turns.
A few more words about winding the transformer. In order to minimize the interference emitted by the toroidal transformer, it is necessary to uniformly fill each layer of windings with a winding wire.
If the first half of the winding you laid the turns to the right, then the second half of the winding of the turns must be laid to the left, without changing the direction of laying the turns themselves around the core.
If it is necessary to wind two identical windings (typical for UMZCH), a double wire is wound onto the spool, and then turns of two secondary wires are stacked from the spool at the same time, as shown in the photo.
In my case, three primary layers are laid in one direction, and another three layers in the other. The conclusions of the primary organizations are made as close to each other as possible.
Two resales are wound in the same way, two layers fit in one direction and another 2 layers in the other.
In compliance with these rules, I made a 120-watt toroidal transformer for the Vasilich amplifier with an Alexey Nikitin N-channel output stage, which ensured minimal interference to the input circuits of the UMZCH.
I would be glad if my experience in manufacturing a toroidal transformer is useful to you.
DIY winding transformer features
Winding a transformer with your own hands is not so much a complicated process as a long one, requiring a constant concentration of attention.
For those who start such work for the first time, it can be difficult to figure out what material to use and how to check the finished device. The step-by-step instructions below will give beginners answers to all questions.
Selection of necessary tools
Before proceeding directly to winding, it is necessary to stock up with all the necessary devices and tools for the job:
- From two racks fastened with a wooden board, and a metal rod between them, having the shape of a handle, make a kind of skewer. The rod should be chosen no thicker than 1 cm and insert between the racks in such a way that its axis penetrates the frame of the future device through. Most often, a wooden block is used for such purposes, in which a hole for the axis is made and “adjusted” to the dimensions of the frame. If you have a drill at hand, it will be much easier to do this. The drill must be strengthened so that it is parallel to the table, and its handle can be freely rotated. A rod should be inserted into the drill chuck, after having put on the block with the transformer frame fixed on it, it is better to give a rod with a thread, in this case the block can be fixed by tightening with nuts on both sides. In cases where it is possible to clamp the frame with nuts, textolite plates or wooden planks, there is no need to use the block.
- The winding mechanism can replace the inductor from the telephone, a machine for thread spools, a film rewinder, or some similar device. The main thing is that the process goes smoothly, without disruption.
- Another device without which it will be impossible to wind the transformer on its own is a device for unwinding. Typically, devices of this kind work on the same principle as devices for winding, the only difference is that in this case you can do without a rotary knob.
- To calculate the number of turns, you will need a separate device, for example, a water meter, a speedometer from a bicycle, an electric meter. To make the device work, it must be connected to the winder with a flexible roller. If you cannot find such a device, then the turns can be counted verbally.
Types and methods, directions of winding transformer windings are presented in the photo:
Winding layers insulation
In some cases, inserts for insulation are required between the wires. Most often, capacitor or cable paper is used for this.
The middle of adjacent transformer windings should be more insulated.
To isolate and level the surface under the next layer of the winding need special varnish, which needs to be wrapped on both sides with paper.
If there is no varnish, then you can solve the problem using the same paper folded in several layers.
Insulation paper strips should be 2-4 mm wider than the winding.
- Fasten the wire with the coil in the device, and the transformer frame is in the winding device. Rotations do soft, moderate, without disruption.
- Lower the wire from the coil onto the frame.
- Leave between table and wire minimum 20 cm, so that you can place your hand on the table and fix the wire.
Also on the table should be all related materials: sandpaper, scissors, insulation paper, included soldering tool, pencil or pen. With one hand, gently rotate the winder, and with the other, fix the wire. It is necessary that the wire lay flat, turn to turn.
On winding transformer coils with your own hands, see the video clip:
If a break occurs during winding, then:
- thin wires (thinner than 0.1 mm) twist and brew;
- wire ends of medium thickness (less than 0.3 mm) should be freed from insulating material by 1-1.5 cm, twisted and soldered;
- thick wire ends (thicker 0.3 mm) you need to peel and solder a little without twisting;
- insulate the place of soldering (welding).
If a thin wire is used for winding, then the number of turns should exceed several thousand. The winding must be protected from above with insulation paper or dermatin.
If the transformer is wrapped in thick wire, then external protection is not required.
After the winding is finished, need to test the transformer in action, To do this, connect its primary winding to the network.
To check the device for short circuits, the primary winding and the lamp should be connected in series to the power source.
Insulation Reliability checked by alternately touching the output end of the wire of each output end of the network winding.
The transformer should be tested very carefully and carefully so as not to get under the voltage of the boost winding.
If strictly follow the instructions and do not neglect any of the items, then winding the transformer manually will not present any difficulties, and even a beginner can cope with it.
DIY winding transformer
Welding inverters are inexpensive, purchasing them today is not a problem. Nevertheless, many home masters are interested in the question of how to make a transformer (welding) with your own hands.
How difficult it is, and how the home-made device will work. In principle, to do it with the right approach is not difficult.
The main thing is the winding of the transformer, because the power of the unit, the quality of its operation, depends on the correctly selected number of turns, on the cross section of the wire used.
So, before you wind the welding transformer, you need to calculate it for all the required parameters. It should be noted that the calculation does not always comply with standard rules and schemes, because the welding machine is sometimes assembled from materials that are not used in the assembly process at the factory. That is, what they found, then used.
For example, not the best transformer iron or winding wire was used. But even after such a winding, the transformers are perfectly cooked, although they are humming and very hot.
We add that when choosing transformer iron, you need to pay attention to such an indicator as the shape of the core. It is armored or rod. The second type is used in home-made welding transformers more often, because they have the best efficiency.
True, the complexity of winding the transformer with your own hands is much higher. But this does not scare the masters.
We add that the transformer can be wound according to several schemes.
- A network winding is when both coils are obtained equal in number of turns and they are connected in series.
- Both windings are connected in a counter-parallel fashion.
- Coiled wire is located on one side of the core.
- The same as in the previous position, only on two sides connected in series.
The simplest scheme is the last. It is usually used to assemble a transformer at home. In it, the secondary winding consists of two equal halves. And they are located on the opposite shoulders of the magnetic circuit. The connection, as mentioned above, is consistent.
The calculation is based on theoretical parameters, on the basis of which it is necessary to make a choice of the actual parameters of the magnetic circuit. The main parameter of welding is the current that is supplied to the electrode.
Since in everyday life, electrodes with a diameter of 2 are most often used; 3 or 4 mm, then a current of 120-130 amperes will be sufficient for them.
Now you can correctly calculate the power of the welding transformer using this formula:
P = U x I x cos φ / η
U is the open circuit voltage, I is the current strength (120-130 A), cos φ is assumed to be equal to 0.8, η is the coefficient of performance, which for self-made welding machines is 0.7.
The calculated value of power should be checked according to the table with the cross section of the magnetic circuit. The table value with these parameters is usually 28 cm², but in fact it is necessary to choose from the range of 25-60 cm². Now, according to other reference tables, the number of turns of wire is selected relative to the core section.
A very important point. the larger the area of the used core for the transformer, the fewer turns in the coil should be. The thing is that a large number of wound turns may not fit in the hole of the magnetic circuit. The calculation of the number of turns is made here according to this formula:
N = 4960 × U / (S × I), where U is the voltage of the power source on the primary winding, I is the current of the secondary winding, in fact, this is the same welding current, S is the cross-sectional area of the core.
And the number of turns on the secondary winding can be calculated using the ratio:
U1 / U2 = N1 / N2
The open circuit voltage on the secondary winding in self-made welding transformers is 45-50 volts.
How to wind a transformer
So, the calculations are carried out, the parameters of the used elements of the step-up transformer are determined, the winding circuit is determined, you can proceed to the rewinding process itself. But before that, you need to deal with the wires that will be wound around the core.
A copper wire in fiberglass or cotton insulation is wound on the primary winding. No rubber. Based on the current strength on the primary winding equal to 25 amperes, the cross-section of the winding wire is 5-6 mm².
The cross section of the wire on the secondary winding should be 30-35 mm², because a large current (120-130 A) flows through it. Particular attention to the insulation of this wire, it must be heat-resistant.
Now everything is ready, you can proceed to winding a teroidal transformer.
Before you rewind the transformer, you need to understand one truth that the wires of the primary winding are subjected to high loads, because a smaller conductor is used here. In addition, the density of the stacked turns is higher here, so they are heated more. That is why the quality of laying in the primary winding should be given special attention.
It happens that a makeshift transformer is assembled not from a single piece of wire, but from several pieces. There is nothing wrong with this, because the ends of the pieces can be connected. You can not use twisting for this, it is better to connect the two ends with a copper wire in several turns, and then solder the joint and insulate or weld.
It is necessary to wind the turns carefully, tightly pressing them to each other. In this case, the laying of the wire should be carried out not strictly perpendicular to the tangent iron, but a little to the side. But as if in front should go the inner winding. This will simply provide ease of pressing the next turn to the previous one. There is no need to trim the wire.
Please note that during the rewinding of the transformer, the wire is fed in an even state. Kinks and bends will only complicate the process itself. Therefore, it is better to wind the wire on your hand and pull it during installation.
To wind the toroidal transformer, it is necessary to insulate each laid layer. To do this, it is better to use a special impregnated latot cloth, which, when touched, adheres to everything.
Or you can use construction tape, which is wound on a transformer with your own hands. Most conveniently, if the tape is cut into strips 15 mm wide.
It is easy to cover a layer of wire with them, and at the same time you need to try to make sure that the inner part of the winding is covered with insulating material in two layers, and on the outside in one.
After that, the entire winding must be lubricated with PVA glue. First, it will strengthen isolation by making it monolithic. Secondly, the winding will not hum. PVA should not be regretted, it is necessary to treat the entire surface well with them. After that, the device must be dried. And then still wrap a layer of turns and so on until the welding transformer is completely ready. DIY winding of the toroidal transformer is completed.
Correctly rewound transformer is a guarantee of high quality and long-term operation. A rewound device will work just like a practically new one. Of course, it buzzes harder, but everything else is still the same necessary device.
As a core, mainly profile plates made of a special alloy are used. They are collected according to the required thickness, taking into account the calculated cross section of the core. There are several forms of plates, but the most commonly used are W-shaped elements.
The transformer frame is, in principle, an insulator that protects the core from the windings. The coil also rests on it.
The frame and the dielectric material are made, it must be thin (0.5-2.0 mm) to fit in the window of the core. If the old transformer is rewound, then the functions of the frame can be performed by cardboard, textolite, and so on.
The dimensions of the frame and its shape are determined by the parameters of the core. But the height of the structure should be larger than the size of the winding.
For toroidal transformers, it is better to use copper wires coated with protective enamel. For welding machines, it is better to use copper or aluminum wires with cellulose, cotton and fiberglass insulation. The latter species is not the best.
It copes with loads, especially with high temperatures, but in the process of vibration the fibers are delaminated, and this is a violation of the insulating layer. As for the lead wires, it is optimal if they are of different colors. This will simplify the connection method.
As you can see, rewinding your own old transformer is not very difficult. This, of course, will take a lot of time, but the device will work well. In any case, it will be cheaper than buying a new one.
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How to make a toroidal transformer with your own hands
Today, many home electricians are thinking about how to make a toroidal transformer. This demand for it is ensured by the fact that it has a core, which is much better compared to others. It has less weight, which may differ by one and a half times. Also, the efficiency of this transformer will be significantly higher.
Here are the main reasons that stop many craftsmen in its manufacture:
- It’s hard enough to find a suitable core.
- Its production takes a lot of time.
Toroidal transformer and its calculation
In order to greatly facilitate the calculation of a toroidal transformer, you need to know the following data:
- The output voltage that will be applied to the primary winding U.
- The core diameter is external D.
- Core inner diameter d.
- Magnetic core
The most important characteristic of the core is the area of its window S. This parameter will determine the intensity of removal of excess heat. The optimal value of this parameter can be 80-100 cm. It is calculated by the formula:
Thanks to these values, you can easily calculate its power by the formula:
P = 1.9 Sc S0, where Sc and S0 must be taken in square centimeters, and P will be in watts. Then you need to find the number of turns per volt:
When the value of k becomes known to you, it will be possible to calculate the number of turns in the secondary winding:
It is better to make calculations if the voltage on the secondary winding is used as the initial value:
W1 = (U1 w2) / U2, where U1 is the voltage that is supplied to the primary winding, and U2 is removed from the secondary.
The welding current is easiest to regulate by changing the number of turns in the primary winding, since there is less voltage.
Toroidal core fabrication
Toroidal transformers contain a complex core in their design. The best material for its manufacture is considered transformer steel.
In order to make the core of the toroidal transformer you need to use steel tape. It must be rolled up, which will take the form of a Thor.
If you already have this form, then no problems should arise.
You can also find a good finished core on a laboratory autotransformer. You should rewind its windings. Measuring transformers have a simpler core.
Another method of manufacturing a toroidal core is the use of plates from a faulty industrial transformer. First, you need to make a hoop from these stitches. Its diameter should be 26 cm. Inside this hoop, it is necessary to gradually insert the plates. Make sure that they do not unwind.
Winding toroidal transformer
Winding a toroidal transformer is a rather complicated process that takes a lot of time. The toroidal transformer has one of the most complex windings. The easiest way is to use a special shuttle.
A wire of the desired length should be wound on it and then through the holes. It has a complex structure, but this does not affect the principle of operation of the toroidal transformer. After passing through the shuttle, the corresponding winding will begin to form.
We hope that thanks to this article you can make a toroidal transformer yourself.
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