We collect the transformer at home

There are situations in life when you need a transformer for a specific case. For example, the network tr-r burned in your favorite receiver, but this is not for replacement, and there is no way to get a similar one. But there are all kinds of other trp-ry from the old technology, which are lying around, that they can try to use as donors, or you can alter it for specific parameters. Next, we will tell you how to make a transformer yourself at home, providing all the necessary calculation formulas and assembly instructions.
  • Estimated part
  • Production order

Calculation part

So, let's start. A small digression for entering into the course of the case. The transformer is a converter of one kind of energy to another and back. It usually consists of two electrical coils( primary and secondary) and iron core sheets. The primary winding induces a magnetic flux in the magnetic circuit, which in turn induces an electric current in the second coil, as shown in the diagram below.

Homemade dressing

Scheme of work

The size of the iron depends on the power of trance, so when designing and assembling repel from its availability for the core. Any calculation of the motor units starts from calculating the overall power of the transformer. Therefore, in order to make a transformer from improvised means, first we need to find the power of the secondary circuit. If the secondary voltage coil is not one, then they need to be summed up. The calculation formula will be:

P2 = U2 * I2


  • U2 is the voltage on the secondary winding;
  • I2 - secondary current.

Having received the value, it is necessary to make the calculation of the primary winding, taking into account the losses on the transformation, we assume an efficiency of 80%.

P1 = P2 / 0.8 = 1.25 * P2

From the power value P1, the core is selected, its cross-sectional area S.

Section Definition

S = √Р1


  • S in centimeters;
  • P1 per watt.

Now we can find out the effective transmission and transformation ratio:

w '= 50 / S


  • 50 is the network frequency;
  • S - cross section of iron.

This formula has an approximate value of the result from the classical solution, but for self-made assembly and simplicity, the solution is quite suitable. After finding the solution, we can start calculating the number of turns, which can be done using the formula:

w1 = w '* U1

w2 = w' * U2

w3 = w '* U3

Since the calculation is simplified and a slight voltage drop under load, increase the number of turns by 10% of the calculated result. Next we need to correctly determine the current of our windings, relying on the primary winding:

I1 = P1 / U1

Determine the diameter of our wire according to the formula:

d = 0.8 * √I

In Table 1, select the wire with the desired cross section. If there is no suitable value, rounding should be done up to a table diameter.

Table of sections

If the calculated diameter is not in the table, or if the window is filled too much, you can take a few wires of a smaller cross section and get the sum you want.

To find the coils on our home-made transformer, we need to calculate the window area of ​​the tube, this is the core formed by the core into which the coils are placed. The already known number of turns is multiplied by the wire cross-section and filling factor:

s = w * d² * 0.8

This calculation is made for all windings, primary and secondary, after which it is necessary to sum the area of ​​the coils and make a comparison with the area of ​​the magnetic circuit window. The core window should be larger than the area of ​​the coils.

Types of magnetic cores

Manufacturer's order

Now, with calculations and material for assembly, you can start winding. We prepare the laying of the first winding for the prepared cardboard coil. To do this, it is convenient to use an electric drill, clamping the coil with attachments fasten in the chuck, fixing on the table or workbench drill, at low speed, we produce a wire laying, one to one in a row. Between the layers of the wire, we settle one layer of insulation, condenser paper. Between the primary and secondary winding, two layers of insulation must be made.

Winding technology

Much easier if we plan to rewind the finished transformer for the desired voltage. In this case, it is sufficient to count the number of turns of the secondary winding when unwinding, and knowing the transformation ratio:

w '= U2 / w2

It is possible to calculate the required number of turns for the required voltage:

w2 = w' * U2

demonstrates how to assemble the transformer at home:

Winding technology
YouTube Trailer
Test work

YouTube Trailer
This article describes the instructions that are available to explain how to make a transformer by hand at homex. For example, we described the sequence of calculating and assembling an armor model, as the most common type of transducers. Its popularity is due to the simplicity of the manufacture of the motor units, the ease of assembly, repair and alteration. On the basis of this homemade it is easy to make a tr-r for charging a car battery, or to make a boosting tr-p for a laboratory power source, an electric wood burner, a hot knife for cutting a foam or another device for the needs of a home master.

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