How to make a transformer with your own hands: step-by-step instructions, diagrams and drawings for making a transformer from scrap materials at home

Widest scope of application

The simplicity of assembly and high efficiency of transformers became the reason for their inclusion in the composition:

Power supplies;
TVs;
Microwave ovens;
Radio stations;
Welding machines;
Communication equipment;
All kinds of automation
Control and measuring equipment.

Indicators of the condition of a high-voltage diode

Wire pv-3: technical characteristics, cross-sections, application

If you decide to take the measurement yourself, you need to know how it works correctly.

If the element is in good condition, the multimeter's index arrow will show 0.25 volts. If you check the resistance in the opposite direction, it will not show anything.
The failure of the part is indicated by the absence of indicators when measuring in all directions. If a fault occurs, the mechanism lamp will glow evenly or not light up at all.

Considering the above data, we can conclude that the high-voltage diode in the microwave is faulty and must be replaced with a new element. After replacing the element, the microwave oven will function like new.

When checking the resistance on both sides, it is important to know: the terminals differ in purpose and connection. The mechanism element with the + sign is marked on itself and ends with a bolt at the end - this is the anode

The mechanism element with the + sign is marked on itself and ends with a bolt at the end - this is the anode.

The terminal with the sign - has a connection to the capacitor, and it ends with a bracket - this is the cathode.

If the microwave strip is not a faulty high-voltage diode, it will be difficult to repair and check it yourself.

Personal assembly

Many radio amateurs and simply curious people periodically ask how exactly to assemble this or that transformer on their own.

Despite the simplicity of solving this problem, you still need to have some skills in working with radio components and understand the physical principles of operation of this device.

Naturally, you will first have to carefully study the entire technology:

Core preparation;
Winding coils;
Applying layers of insulation.

Capacitor check

Osm transformer characteristics, osm 220/220 designation

If you have a need to check the serviceability of this element in a microwave oven, you need to approach this matter responsibly. This will prevent damage to other electronics located in the microwave.

Typically, testing is carried out when a malfunction is identified or when there are other failures in the correct operation of the microwave.

Below are instructions on how to perform the test correctly and which device is best to do it with.

How to find a capacitor in a microwave

When working with a capacitor there is a possibility of interaction with high voltage and this can be very dangerous. In order to protect yourself from the possible negative effects of current, you must first turn off the microwave oven from the network.
After unscrewing the back cover on the device, you need to remove the closing panel. Depending on the design of the furnace, it will not be difficult to find the capacitor; it is enough to know approximately what it looks like. Usually the part is located near the transformer.
Regardless of how long the device has been without power, it is imperative to discharge the part.

Only after the above operation can you start working with it.

Using a Multimeter to Test

For diagnostics you will need a special device - a multimeter. Its functions include testing various electrical devices or individual parts.

To check using a multimeter, the device is set to ohmmeter mode. The multimeter prepared for use is connected to the capacitor.

The limit depends on the type of device, so it is different for everyone.

After the first reading of the readings, it is necessary to rearrange the probes and monitor the dynamics of changes in the result displayed on the device.

However, verification by this method occurs at a low rate. Usually, at this voltage, in high-voltage capacitors, if they have a leak or are broken by a short circuit, the breakdown is not detected.

In order to avoid such inaccuracies, you can use a megohmmeter with an external high voltage source equal to the operating value of the capacitor.

Among the main megohmmeter models suitable for such a test are the following:

PU182.1 (500 V);
PU186 (2500 V);
KEW-3125 (5000 V).

Clarification of a number of technical parameters

However, before starting the practical part, you will need to give clear answers to a number of questions.

How exactly should the future unit change the current: increase it or decrease it?
What voltage will be supplied to the primary coil and removed from the secondary?
What will be the operating frequency of this device?
How much power should it have after assembly is completed?

How does a magnetron work?

A magnetron is a vacuum tube that performs the functions of a diode and consists of several main parts:

a cylindrical copper anode, which is divided into ten parts;
in the center there is a cathode in which a filament is built in, and its main function is to create a flow of electrons;
at the ends there are ring magnets necessary to create a magnetic field, which provides microwave radiation;
a wire loop connected to the cathode, which is removed from the magnetron using a special emitting antenna and directed along a waveguide into the chamber; its main function is to collect radiation.

During operation, the magnetron heats up greatly, and therefore the case of this device is initially equipped with a special plate radiator and a blown fan. To protect this element from overheating, the power circuit has a thermal fuse.

The benefits of a detailed drawing

After providing comprehensive answers to the above questions, a diagram of the transformer device can be drawn up on paper or on a computer. It is not superfluous to do this even with a clear understanding of all the parameters and features of the radio component.

Often a drawing allows you to significantly clarify

Scheme of connecting and bringing out contact wires;
Number of plates in the W-shaped core;
Method of arrangement of primary and secondary coils.

Excellent homemade transformer from a microwave for a car

This homemade product is designed to unscrew stuck and rusty nuts by heating them with electricity. Everything is done quickly and simply.

For homemade work, we need a transformer from a microwave oven.

The secondary winding will need to be removed from it. I cut the secondary winding like this, took a grinder and carefully cut the winding, I repeat once again, cut carefully so as not to catch the primary winding.

When the winding is cut off, the remains are simply knocked out with a hammer and submitted for metal color.

Now our transformer is ready to wind another, secondary winding.

But first I connected the power wire to the primary winding; the wire itself was taken from an old iron.

The secondary winding needs to be wound with a wire of 7 mm, I just got 3 turns of such wire, like in the photo.

The device itself is almost ready, now you need to make tongs and contacts that will clamp and heat the nut or part.

To do this, I took one crocodile from the cigarette lighter, attached 2 strips of fiberglass to it (as an insulator), I think that everything will be clear from the photo.

I screwed metal plates to the strips, and to the plates there were already bolts to which the ends of the wires were screwed. Yes, I forgot to say that I took the bolts from the solenoid relay because they are copper.

I put heat shrink on the crocodile's arms.

Well, I decided to immediately make a box for my device, I made the box from leftover chipboard, and I also installed a fan from the computer there to cool the transformer. And I cut off a piece from the timing belt and screwed it on, it turned out to be a handle, and in the end I got this device.

Well, now to the test...

Nails and bolts heat up almost immediately.

The M6 nut heats up in 1 second.

M8 also heats up quickly

M10 is already heating up more slowly.

But here I already tested it in real conditions, the nut did not unscrew on the intake manifold.

Here the device did a great job and the nut was easily unscrewed, but the wires also got hot, but not much, that is, they didn’t melt there, they just got hot.

Of course, if anyone wants to make their device more powerful, then accordingly they need to take wires thicker than 7 mm, take 10 millimeters and I am sure that the device will work many times more powerful, but for me this power is quite enough.

Purchase of components and consumables

After the schematic diagram has been fully prepared, you can begin purchasing the parts and consumables needed for assembly.

Usually, the necessary materials and accessories, including varnished wire and terminals, are easy to find in the first radio store you come across.

First you need to buy

Electrical tape or heat-resistant tape;
Core configuration corresponding to the project;
Insulated wires.

The principle of operation of a microwave oven and its design

By irradiating various objects with centimeter waves, scientists discovered one interesting feature: at a frequency of 2.45 GHz, the rays are capable of loosening microparticles of water, which is accompanied by the release of a significant amount of heat. And since food products contain a large amount of liquid, this specific property began to be used for heating and cooking.

Such a magnetic field is created by a special vacuum lamp - magnetron . To protect the human body, which is 80% water, this emitter was hidden in a metal container, the material and design of which does not allow waves to pass through, capable of bringing any liquid to a boiling point in a very short time. Isolation of the magnetic field in a narrow space only made it possible to increase the productivity of such a device. After all, heat stopped dissipating and only began to accumulate, accelerating the heating process. For a more uniform impact of waves on the product, a table rotating around its axis was installed inside.

The microwave chamber is equipped with a glass door so that you can observe the cooking process. The glass is coated with a material that reflects radiation. And to remove steam and excess heat, holes are provided that do not allow microwave waves to pass out.

Assembling the winding machine

When making this electrical device yourself, you will need to wind the wire. Winding a transformer with your own hands is carried out on a simple homemade machine tool. You can do it in a couple of hours.

First you need to take a board measuring 10x40 cm. A couple of bars measuring 50x50 mm should be attached to this base with screws. The distance between them should be at least thirty centimeters.

Methods for diagnosing device performance

The simplest way to check the functionality of a transformer is to replace the existing device with a known good one.

Secure Verification Method

The safest diagnostic method is to check the integrity of the transformer windings with a multimeter. The entire process is performed sequentially. Using a measuring device (set to certain limits), the resistance of the primary winding and two secondary windings of the dismantled and disconnected transformer is determined. If there is a break, the display will display 1. If the circuit is closed, the readings for the primary winding (the device is set to 200 Ohms) should be in the range of 2 - 4.5 Ohms, the filament - 3.5 - 8 Ohms, and for the high-voltage secondary (switch set to 2000 Ohms) their range is already 140 - 350 Ohms.

If the resistance goes beyond the specified limits, this indicates the presence of an interturn short circuit.

When taking measurements, you need to take into account the magnitude of the multimeter’s own error. It is determined by short-circuiting its probes to the limit used. The value given will be an error that must be taken into account.

You can either check the transformer in the microwave yourself with the device, or entrust this task to professionals from the workshop. The first case will require knowledge of the basic fundamentals of electrical engineering and some working skills.

Reel Rods and Handle

Next, miniature holes with a diameter of 8 mm are drilled. Rods are inserted into them onto which the transformer coil will be strung.

All that remains is to apply a small diameter thread, tighten the washer and mount the handle.
It is important to note that the dimensions of such a machine can be anything.
In other words, it can be fully adapted to the intended core size.
However, if the project involves the use of a ring core, then it will have to be wound entirely by hand.

High voltage source in 5 minutes

From this article you will learn how to get high voltage, high frequency with your own hands. The cost of the entire structure does not exceed 500 rubles, with a minimum of labor costs.

To make it, you will need only 2 things: - an energy-saving lamp (the main thing is that there is a working ballast circuit) and a line transformer from a TV, monitor and other CRT equipment.

Energy-saving lamps (correct name: compact fluorescent lamp ) are already firmly established in our everyday life, so I think it will not be difficult to find a lamp with a non-working bulb, but with a working ballast circuit. The CFL electronic ballast generates high frequency voltage pulses (usually 20-120 kHz) which powers a small step-up transformer, etc. the lamp lights up. Modern ballasts are very compact and easily fit into the base of the E27 socket.

The lamp ballast produces voltage up to 1000 Volts. If you connect a line transformer instead of a lamp bulb, you can achieve amazing effects.

Effect of power on the number of turns

A transformer made by yourself can be equipped with any number of turns.

The instructions on how to make a transformer indicate that the required number of turns is calculated based on the power of the intended device.

Tips for connecting two devices

Let's say there are two identical transformers having the following parameters:

Power value – 500 W;
input voltage indicator – 220 V;
output voltage indicator – 2 V;
current indicator - 250 A.

If you make the correct connection, you will get double the current strength, that is, 0.5 kA.

There will also be an increase in short-term current. But when creating a short-term current, losses can be seen. This is a consequence of the huge resistance of the electrical circuit. It is necessary to connect both ends of the secondary winding to the electrodes of the unit, which is intended for spot welding.

First scheme

It happens that if there are two high-power transformers, the output voltage is not quite enough to create a device. In this situation, it is necessary to connect their secondary windings. They must have the same number of turns.

When connecting them, it is necessary to ensure that the direction of the turns is consistent. If this condition is not met, then an antiphase will be created, and the output voltage will be almost zero.

Second scheme

Computing application for Android

Mathematical expressions that can be found in specialized literature will provide reliable assistance in clarifying a number of parameters. Almost all of these formulas have already been included in computer programs, which in most cases makes it possible to minimize the calculation part.

You just need to specify some data about the future device in the program interface, and the smartphone application will display a comprehensive table with the requested information.

Wire diameter

The parameter is determined by the strength and current density, on average 2 A/mm2.

On the 1st winding: I = P1 / U1.
Without insulating material: d = 0.8*I^0.5 – the root is calculated from the current indicator.
Cross section: s = 0.8*d^2 – squared.

If there is no product with the resulting diameter, you can take several thinner ones and connect them in parallel so that the total cross-section is larger than the calculated one.

For a thick wire in the last formula, the coefficient can be 0.65-0.7. To avoid calculating it, you can use the table:

Next, the area with insulating material is determined: s' = 0.8d^2 - but here the characteristic is taken from the table, with insulation.

To obtain the area of the core window, sum up all the area readings obtained and multiply the indicator by 2 or 3.

Frame production stage

The frame part is made of cardboard. Those who do not yet have experience in such assembly and therefore do not know how to make a transformer frame with their own hands must take into account that its internal part must have larger dimensions than the core.

If a ring-shaped core is used, there will be two coils. When choosing an W-shaped core configuration, there will be only one coil.

What material is the magnetic circuit made of?

If you need a low-power converter, a rod or armored magnetic circuit is suitable. In the first version, the rods are located vertically. In the second case, the rods have a rectangular cross-section and are located horizontally. This design is more complex and therefore less common.

In step-up, W-shaped ferrite magnetic cores are often installed; the difficulty in the design lies in the need to select the exact size of the rod. If a spare part from another equipment is used for assembly, the thickness of the plate package is determined based on the power. The plates are inserted into the coil and tightened with nuts and studs.

Winding wire and applying insulation

If a round core was chosen as the base, then it should first be wrapped with electrical tape. Next you can start winding the wire.

After the application of the primary winding is completed, it is covered with dense insulation.
Then it’s time to wrap the second layer.
The ends of the windings are brought out, and contacts are soldered to them for interfacing with other equipment.

Transformer in an electrical circuit

The simplest circuit involving a high-voltage transformer contains:

magnetron;
diode;
network filter;
high voltage capacitor;
door lock switches;
fuse;
electric motors for ventilation and rotation of the pallet;
control module;
lamp for illumination.

Starting the oven, which is only possible with the door closed, involves moving the tray and cooling the magnetron fan. If the lamp temperature reaches more than 105°C, the thermostat will operate, which will cut off the voltage supply to the primary winding of the transformer.

In expensive models, the circuits are additionally equipped with program-controlled units, LCD displays, dissectors, grills and steamers. And the high-voltage transformer is replaced with a complex pulse unit, which lightens the weight of the entire structure.

Windings for increasing voltage

The reel is placed on a block of wood. It should already have a hole for the winding rod. The further sequence of actions is as follows.

A couple of layers of varnished fabric are wound onto the reel.
The tip of the wire is fixed on the cheek, after which the handle begins to rotate.
The laying of the coils must be monitored and, if necessary, compacted.
At the end of the primary winding, the wire is cut and fixed on the cheek.
The working terminals of the windings are wrapped with electrical tape or covered with heat-shrinkable tubing.

Procedure for safe inspection

When starting an independent test, you need to stock up on a multimeter (in extreme cases, a two-pole indicator with a built-in power source), screwdrivers with various tips, an ohmmeter, and pliers.

The general scheme of safe work looks like this:

disconnect the device from the power supply;
unscrew the screws and remove the casing;
discharge the capacitor;
carefully remove the terminals from the transformer;
check its windings: if the parameters are normal, replace them and look for other reasons;
when a break or short circuit is found in them, the device is replaced;
The oven is assembled and its functionality is checked.

If, after removing the transformer, traces of insulation melting are visible on its windings, and a strong burning smell emanates from it, then it is no longer suitable for use, and there is no point in checking it. In this case, only replacing the device

Before you begin examining the transforming device, you must make sure that it is receiving power. To do this, you should use a multimeter to check the presence (after turning on the device into the network and starting the heating program) at the connection points of the primary winding of an alternating voltage with a value of 220 V

This work must be performed with extreme caution to avoid electric shock.

The presence of a high-voltage capacitor capable of storing an electrical charge leads to the need to discharge it before carrying out testing work

. This is done by simply connecting its contacts to each other (with a screwdriver, pliers) or to the housing when the voltage is turned off.

First start-up and diagnostics

It is likely that when you first start up a new device, it will begin to make a characteristic ringing sound. This means that it is necessary to better secure all fasteners.

Next, a new test of the transformer is carried out. It is connected to the network, after which the voltage on the secondary winding is measured. If it corresponds to the design, albeit with slight deviations, then the new device can be used for its intended purpose.

It is advisable to leave it under voltage for two to three hours after starting. In this case, you need to make sure that it does not heat up excessively.

Superconducting transformer almost with your own hands

Back in 2016, one young but very impressionable fourth-year student at the Faculty of Energy was influenced by an article in which the author very popularly showed what high-temperature superconductors (hereinafter referred to as HTSCs) are today.
Blinded by the desire to revive the rather monotonous and extremely conservative electric power industry in his soul, making his way through a veil of contradictions and an acute lack of finance, the young bachelor, together with his colleagues, nevertheless built a transformer with windings from a high-temperature superconductor. Enjoy reading! Why make transformers superconducting?
The current products of transformer manufacturing have truly achieved, in a sense, an ideal.
Large power transformers, the same ones that are located in brick or iron transformer substations (TP-ears) in your yard, as well as larger representatives, have an efficiency of about 99%. A huge number of regulatory documents regulate the operation, diagnostics, method of installation and creation of such transformers, and at conferences and exhibitions more and more representatives appear with an innovative nut in the core of the magnetic circuit or revolutionary oil with a reduced concentration of gases dissolved in it. A typical representative of power transformers
And, it would seem, where should we ignoramuses go into this area of engineering thought, polished to the smallest detail. Is the extra half a percent of efficiency that superconducting transformer windings can provide worth the expense of organizing a special cryogenic facility, retraining engineers and re-equipping production? Why reinvent the wheel? Primary analysis shows that there is no need. However, let me give one argument, which became the reason why this article subsequently became possible: “What if the bicycle is crash-proof?”

Advantages of a transformer with HTSC windings over a conventional one:

— Almost complete absence of energy losses in the windings (the wires are superconducting, they do not heat up); — Explosion and fire safety (liquid nitrogen, unlike transformer oil, does not emit explosive gases); — Less weight and dimensions (the current density in a superconducting wire can be 10 times higher than that in a copper wire, at the same voltage); — Ability to limit short circuit currents

Although the first three advantages are strong, they all pale in comparison to the huge price that has to be paid for superconductivity. Therefore, I’m afraid the commercial success of HTSC transformers can only occur in particularly demanding types of military and space equipment or at facilities with special fire safety levels. However, the fourth property can dramatically change the picture, and personally, it alone seems to me to be sufficient to not only pay attention to the HTSC paradigm, but also to conduct some research. In fact, this is what many of my colleagues around the world have done, take at least the works [1-3]. What's the trick here?

About the physics of current limiting

At the moment, when talking about HTSC wires in the context of the electric power industry, we almost always talk about composite HTSC tapes based on ceramic compounds. As you can see from the image below, the superconductor (YBCO layer) deposited on a metal substrate is covered on all sides with some protective layer. This protective layer can be some metals and their alloys, such as copper. Naturally, these materials do not have superconducting properties at the temperature of liquid nitrogen, which means that if the superconductivity of YBCO ceramics disappears for some reason, then the entire current is parallelized between these layers, in accordance with their resistive resistance.

Any current is proportional to the voltage applied to a given resistance, which means that if suddenly, out of nowhere, resistance appears in the circuit where it was not there before (superconductivity has collapsed), then the current (at a constant voltage) will decrease.
Moreover, the degree of this reduction depends on the resistance of the materials surrounding the HTSC layer. But how to destroy superconductivity? There are actually 2 fundamental ways: raising the temperature above the critical one, at which superconductivity cannot exist, or influencing the HTSC with a magnetic field above the critical one. Moreover, if a current flows through a superconductor, then it also creates a magnetic field that tries to penetrate this superconductor, and if the current creates too much of a field, then the superconductivity begins to gradually
collapse.
The current at which superconductivity begins to break down is usually called critical
.

Let's build a transformer!

That's it! Now, I’m sure you understand enough to start building a transformer, and believe me, for me it was a really exciting journey, because if winding wire for a regular transformer (hello to those who wound it) is a very meticulous and rather tedious task, then for a HTSC transformer the complexity increases significantly. Especially when such a device is assembled from scrap materials. Let's find out why!

Winding frames

One of the serious disadvantages of a HTSC transformer is that the core is not and cannot be superconducting. Therefore, we have two options on what to do: heat and waterproof the core from the windings, increasing the distance between it and the windings and reducing the efficiency, or put the core in nitrogen along with the windings, creating a large boiler for nitrogen, since the no-load losses of the transformer are nowhere to be found children We decided to take the first route, making a cryostat in the form of a hollow cylinder. Why did you choose this as a frame for the secondary winding (which is closer to the core):

Polypropylene pipe and wrapping paper next to it

Pipe with an internal diameter of 100 mm. made of polypropylene is an ideal waterproofing material, but not a very good thermal insulator. Moreover, some types of plastic tend to shrink at low temperatures, which is why the winding wound directly on such a pipe can be deformed along with the pipe. Therefore, it was decided to additionally reinforce this pipe by wrapping it on top with paper impregnated with epoxy resin. There were no problems with paper; you can get plenty of it at the exits of various (large) hardware stores (ala Leroy), where it is free. It's heavier with compound. We had no experience working with homemade paper-based PCBs, and we did not know how a paper-impregnated frame would behave at -196 degrees Celsius. We consulted and decided to take the first ED-20 epoxy resin we came across. When purchasing the resin, we were warned that the hardener (the second component with which the resin is mixed, after which it hardens during a chemical reaction) works in 20 minutes. Why it immediately became clear that it would be impossible to hesitate and the paper would have to be soaked quickly. For this purpose, faithful comrades appeared in the form of a human assembly line.

Improvised conveyor for impregnating paper with epoxy resin

The smell was, frankly, not very good. Also, take care of your hands when working with compounds!

Paper impregnation process

The second frame (for the outer winding) was made in the image and likeness of the first and directly on top of it. To prevent the frames from sticking together, they placed a little random material, which could later be torn off. The result was:

Ready-made frames for windings

To summarize this part, I will say that there is probably simply no cheaper way to create two non-magnetic, non-metallic, cryo-resistant and sufficiently strong frames. The most expensive element in creating the frame was, of course, the compound ~500 rubles/kg, followed by the PP pipe, and then brushes and gloves - this is optional.

Windings

Perhaps the central and most expensive element of this story is the HTSC windings themselves. The reason why the title of this article contains the word “almost” is the price. We purchased 40 meters of HTSC tape, 4 mm wide and 0.1 mm thick, with a critical current of 80 A at a price of 2,500 rubles per meter. Clearly physical. a person is unlikely to pay for something like this. Let's look at their dazzlingly expensive grandeur.

A dazzlingly expensive part of the project described

In addition to the high cost, HTSC tape is also a very fancy material. It does not like severe overheating (over 500 degrees), it has a large maximum bending radius (about 20 mm, if exceeded, the superconductor will begin to deform), and it also cannot be twisted, crushed, or beaten. All this turns working with HTSC wires into a kind of jewelry art. How are we going to wind it?

To be honest, the method chosen for winding the tape on the frame is probably the most primitive. The tape is covered along one side with Kapton tape

, and the edges of the tape protruding beyond the tape are glued together with the tape to the frame. As a result, during the winding process we obtain two factors that hold the winding on the frame: the adhesion of the adhesive tape and the PCB surface and the friction force of the tape on the same surface. In the end, surprisingly, it turned out to be quite reliable.

Kapton tape was not isolated by chance. The fact is that not every material can be reliable insulation at low temperatures. For example, ordinary tape becomes almost glassy and shrinks. The electrical tape also shrinks. Electrical insulating varnishes crack (though not all of them), PVC insulation also shrinks. Kapton (or polyimide) tape behaves extremely calmly at low temperatures (as well as at high temperatures), it is traditionally chosen for HTSC wires when you need to do something “quickly”, although it must be said that it is not cheap compared to ordinary with tape. When you need to do something thorough, they use a coating that is also based on polyimide.

The process of winding the outer (primary) winding

Actually, they wound a transformer with the number of turns 50:25, in practice it turned out a little less, but that’s not the point. The primary winding (outer) was single-start (one spiral along the entire height), the secondary winding (inner) was double-start (two spirals alternate). Which actually gives the critical current for the primary = 80 A and for the secondary 160 A. If we take into account that the mains voltage (for which the transformer was made) = 220 V, then we get about 10 kW of transmitted power with virtually no losses, in a fairly small volume. Winding results:

Primary (left) and secondary (right) windings of a HTSC transformer

Soldering

We have reached the most nerve-wracking process in transformer manufacturing. As mentioned above, a superconductor is not a fan of high temperatures. When we talk about a copper wire capable of carrying 60-80 Amps for a long time without overheating, we mean a cross-section of 16 or 25 mm^2. These are quite massive and unruly wires, which are difficult to give the desired elegant shape for convenient soldering with 4 mm HTSC tape. If you take a sufficiently powerful soldering iron and simple solder, you can overheat the tape. Therefore, it is better to take Indium-Tin solder with a melting point of ~103 degrees. S. Better yet, melt it in a soldering bath, cover the tape and wire with soldering acid and get a fabulous glow of self-adoration from a job well done in the reflection of the hot metal.

Nuance. It is better to solder current contacts, not sparing the area of the tape, for better current input. We took 3 cm of tape along the contact surface with the current contact, but more is possible. We removed the voltage contacts from the current contacts by several centimeters, so as not to measure the voltage drop at the contact point, but directly on the winding. Unfortunately, only a photo of the finale of this action has survived.

Windings with contacts

Cryostat

The final and most artisanal part of our production. The cryostat was made of foam plastic and acrylic sealant. That's all. Unfortunately, not every brand of foam will work. Polystyrene foam with large granules, when exposed to nitrogen, will immediately self-destruct with a crash and roar.

Incorrect foam (left) and correct foam (right)

As for the sealant, jokes aside, we took the cheapest one that was available. I don't know what the trick is here. The main thing is that the sealant is acrylic and not silicone, because the latter (as we were assured at the store) can corrode the foam.

The cryostat was prefabricated; squares with round holes were cut out so that the entire structure would eventually fit inside, while a pipe protruded from the outside of the cryostat, into which the magnetic circuit was supposed to be placed in the future. In other words:

Prefabricated cryostat

As can be seen in the photo, the joints of this entire structure were heavily coated and impregnated with sealant. We benefit from the fact that when the sealant hardens under nitrogen, it feels like very thick cheese to the touch and performs its functions extremely well. At the last stage, a special bottom is cut out under the frame pipe, on which it is installed and, finally, this entire structure is assembled into a single HTSC transformer.

HTS transformer

As a result, we got:

VTSPT-10000, 220/110 V, 50/100 A, OHL

Explanation

HTSC T - the last letter means transformer 10000 - power in VA 220/100 - rated voltages of the primary/secondary windings 50/100 - rated currents of the primary/secondary windings OHL - work under very cold conditions
Experiments
I think every experimenter has tested this mixture at least once the trepidation and ruthlessness with which he subjected his “newly-made beast” to torment. Of course, the HTS transformer was designed to be incinerated. However, we will incinerate it carefully - scientifically.

Here I will show the main experiment for which the transformer was made. Let's short-circuit the secondary winding and, using a switch, supply voltage from the mains (220 V) to the primary winding. Since the resistance of the primary winding and the secondary winding magnetically connected to it (through the air) is small, fairly large currents will flow in the circuits. These currents will exceed the critical level of 80 A and, therefore, destroy superconductivity, due to which the HTSC winding will gradually begin to acquire a finite electrical resistance, which in turn will cause current limitation. Which we will record in the form of a distorted current sinusoid. And the appearance of some final values on the voltage oscillogram (instead of zero in normal mode). The measurements will be carried out using a device unexpected for this experience: a power quality analyzer. It is unexpected because the sampling frequency of this device in oscilloscope mode leaves much to be desired. But what can you do? Nevertheless, let's take a look at the qualitative picture of what is happening.

Current oscillograms (points on the graphs correspond to real recorded data)

The oscillograms on the left (for comparison) show the short circuit mode if the transformer is not filled with liquid nitrogen: we see a slightly distorted but calm sinusoid of the short circuit current, which after a period (half a period is shown in the figure) is turned off by the circuit breaker. On the right is the short circuit mode if the cryostat is pre-filled with liquid nitrogen: we see a strong initial increase in the current, which gradually (starting from 150 A) bends under the influence of increasing resistance. However, due to the higher value of the short-circuit current, the circuit breaker trips already in the first half-cycle.

Unfortunately, for now we are content with only these high-quality results, but soon we will definitely make many more.

Conclusion

Of course, the HTSC transformer leaves behind a lot of contradictions. These contradictions are manifested even in the artisanal method of manufacturing such a complex device. What can we say about real working samples, which you can familiarize yourself with [1,3]. The real HTSC power industry has leapt far ahead with the development of cables and current limiters, undergoing difficulties even in these more developed divisions. It is quite popular to get acquainted with them without leaving this site, for example here.

Nevertheless, no matter how controversial this area of engineering knowledge may be, in the end the one who can justify his rightness will remain right, so we will try.

And in any case, it's terribly interesting!

Thank you for attention! Sincerely yours DOK.

I also express my gratitude to:

Vitaly Sergeevich Vysotsky and the VNIIKP team for their help and advice on this difficult journey. Pavlyuchenko Dmitry Anatolyevich for his enormous support and desire to develop this area from scratch!

Literature

1. Dai S. et al. Development of a 1250-kVA superconducting transformer and its demonstration at the superconducting substation //IEEE Transactions on Applied Superconductivity. – 2016. – T. 26. – No. 1. – pp. 1-7. 2. Manusov V.Z., Aleksandrov N.V. Limitation of short circuit currents using transformers with high-temperature superconducting windings // News of Tomsk Polytechnic University. – 2013. – T. 323. – No. 4. 3. Lapthorn AC et al. HTS transformer: Construction details, test results, and noted failure mechanisms //IEEE Transactions on Power Delivery. – 2011. – T. 26. – No. 1. – pp. 394-399.

A guarantee of durability and reliability

In general, the winding and assembly process does not cause much difficulty. This method can produce devices for a range of applications, including halogen lamps.

In order for the result of all the efforts made to be a unit that is actually suitable for use, the winding technique described above must be carefully followed. This will guarantee not only the serviceability of the transformer, but also its uninterrupted operation for a very long time.

Signs and causes of transformer malfunction

The occurrence of problems in a transformer can be determined by the following signs:

smoke is visible and the smell of burnt insulation is clearly felt;
The microwave makes a lot of noise when operating;
food is not heated.

In many cases, malfunctions are caused by power surges in the network: a wire may break or a short circuit may occur. You can do without checking in cases where traces of melting are clearly visible and there is a burnt smell. Then the transformer needs to be replaced.

Advice! Mainly due to changes in the network, the winding coils suffer. This is where you should look for the causes of problems.

The steel plates that make up the frame of the converter must be glued together. If delamination occurs, the transformer begins to make loud noise during operation. In this state of affairs, you need to buy a new device with similar power characteristics and replace the faulty one.

Photo of a homemade transformer

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Precautionary measures

When carrying out measurements under voltage, electric shock, even death, can occur. Two rules will help you avoid danger:

It is strictly forbidden to touch the internal parts of the microwave oven while it is operating. To carry out measurements, you need to put crocodile probes on the tester’s terminals and connect them to sections of the circuit.
If you need to touch high-voltage parts with your hands, you should not only disconnect the stove from the power supply: you can prevent electric shock by shorting the magnetron leads to the housing. Thanks to this precaution you will protect yourself from capacitor discharge. There is a resistor in the microwave electrical circuit to discharge the capacitor, but it does not eliminate the danger 100%. The resistor may burn out or they completely forgot to install it, and such a mistake could cost the life of a do-it-yourselfer.

Repairing any electrical equipment involves the risk of electric shock. When testing a transformer in a microwave, you need to be extra careful due to the high voltage and capacitor. Use safe measurement methods and follow safety regulations.

Microwave oven charger

Some car enthusiasts use a transformer from a broken microwave oven. But this transformer will need to be redone, since it is a step-up transformer, not a step-down transformer.

It is not necessary that the transformer be in good working order, since the secondary winding in it often burns out, which will still have to be removed during the creation of the device.

Remaking the transformer comes down to completely removing the secondary winding and winding a new one.

An insulated wire with a cross-section of at least 2.0 mm is used as a new winding. sq.

When winding, you need to decide on the number of turns. You can do this experimentally - wind 10 turns of a new wire around the core, then connect a voltmeter to its ends and power the transformer.

According to the voltmeter readings, it is determined what output voltage these 10 turns provide.

For example, measurements showed that there is 2.0 V at the output. This means that 12V at the output will provide 60 turns, and 13V will provide 65 turns. As you understand, 5 turns adds 1 volt.

Scheme.

Well, then everything is done as described above - the diode bridge is made, all the components are connected and the functionality is checked.

It is worth pointing out that it is better to assemble such a charger with high quality, then place all the components in a case that can be made from scrap materials. Or mount it on a base.

Be sure to mark where the “positive” wire is and where the “negative” wire is, so as not to “over-plus” and damage the device.

Memory from a tube TV

The first scheme will be, perhaps the simplest, and almost any car enthusiast can cope with it.

To make a simple charger, you only need two components - a transformer and a rectifier.

The main condition that the charger must meet is that the current output from the device must be 10% of the battery capacity.

That is, a 60 Ah battery is often used in passenger cars; based on this, the current output from the device should be 6 A. The voltage should be 13.8-14.2 V.

If someone has an old, unnecessary tube Soviet TV, then it is better to have a transformer than not to find one.

The schematic diagram of the TV charger looks like this.

Often, a TS-180 transformer was installed on such televisions. Its peculiarity was the presence of two secondary windings, 6.4 V each and a current strength of 4.7 A. The primary winding also consists of two parts.

First you will need to connect the windings in series. The convenience of working with such a transformer is that each of the winding terminals has its own designation.

To connect the secondary winding in series, you need to connect pins 9 and 9\'.

And to pins 10 and 10\' - solder two pieces of copper wire. All wires that are soldered to the terminals must have a cross-section of at least 2.5 mm. sq.

As for the primary winding, for a series connection you need to connect pins 1 and 1\'. Wires with a plug for connecting to the network must be soldered to pins 2 and 2\'. At this point, work with the transformer is completed.

Next you need to make a diode bridge. This will require 4 diodes capable of operating with a current of 10 A or higher. For these purposes, diode bridges D242 or analogues D246, D245, D243 are suitable.

The diagram shows how the diodes should be connected - the wires coming from pins 10 and 10\', as well as the wires that will go to the battery, are soldered to the diode bridge.

Don't forget about fuses. It is recommended to install one of them on the “positive” terminal of the diode bridge. This fuse must be rated for a current of no more than 10 A. The second fuse (0.5 A) must be installed at terminal 2 of the transformer.

Before starting charging, it is better to check the functionality of the device and check its output parameters using an ammeter and voltmeter.

Sometimes it happens that the current is slightly higher than required, so some install a 12-volt incandescent lamp with a power of 21 to 60 watts in the circuit. This lamp will “take away” the excess current.

Electrical specifications

To correctly make a model yourself, a number of parameters are determined:

Output power: P2 = U2*I2, which is obtained by multiplying the output parameters. If there are several secondary coils, they are summed.
The efficiency does not exceed 80%, so primary: P1 = P2/0.8 = 1.25*P2.
The area of the central part is calculated based on P1. For steel, this value is: S = P1^0.5 - calculate the root of the primary power value. For tin, baked wire, roofing iron, S is taken three times more: S = 3*P1^0.5.
Turns of the first coil: w1 = 50/S.
Second: w2 = w1*U2.

The w value is increased by 5-10%, because Some voltage is lost due to resistance.

What power will it have?

Once you can answer each of the questions listed, purchase the required materials. You can easily buy the necessary materials in specialized stores. You will need wires, premium quality tape insulation, and a core.

The transformer itself requires winding. For these purposes, a machine should be created, the manufacture of which is carried out from a board forty centimeters long and ten centimeters wide. Several bars need to be attached to the board using screws.

The distance between the bars should not be less than thirty centimeters. Then you should drill holes eight millimeters in diameter. In the created holes you need to insert special rods for the device’s coil.

A thread should be created on one side. By tightening the equipped washer, you will get its handle. The dimensions of the winding machine can be chosen at your own discretion. First of all, the right choice directly depends on the size of the core. With its ring-shaped form, the winding is created manually.

According to the diagram of the transformer device, the device can be equipped with a varied number of turns. The required quantity is calculated based on power. For example, if it is necessary to create a device up to 220 volts, the power should reach at least 150 watts.

The shape of the magnetic wire should be O-shaped. You can make it out of a used TV. In this case, the cross section is determined using a certain formula.

Arrangement of the reel housing

The body is made of high-quality cardboard paper. Its inner side is slightly larger compared to the core part of the core. When using an O-shaped core, several coils will be required. With a w-shaped core, it is enough to use only one coil.

When using a round core, it should be wrapped using insulation. Then you can carry out wire winding. Once you are done with the primary winding, it should be covered with several insulating layers. After this you need to wind the next layer. The ends of the existing windings are brought out to the outside.

When using magnetic wire, the transformer body is assembled step by step:

A certain size of sleeve with the required cuffs is cut out.
Cardboard cheeks are created.
The main part of the coil is rolled up into a special box.
Cheeks are placed on the sleeves.