![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366648_18.jpg)
Once I needed a powerful transformer with bipolar power supply for a low-frequency power amplifier. I searched the bins and didn't find anything like it. Unfortunately, there was nothing like this for sale locally either. Then 3 identical transformers from old music centers caught my eye. And a great idea came to mind: to make one powerful transformer out of three small ones.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366641_1.jpg)
Making a powerful transformer from three small ones
We disassemble the magnetic circuit of all transformers. To do this, we first knock out all the “I”-shaped elements located in a checkerboard pattern, and then all the “W”-shaped plates.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366599_2.jpg)
We remove layers of insulation and windings from the frames.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366656_3.jpg)
We saw off the end of two frames only on one side. And the third has both ends, so that only the side plates remain.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366657_4.jpg)
Using super glue we glue the frame together.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366604_5.jpg)
We wrap it with the first insulating layer for proper fixation. We remove possible spreading of the glue with a file after hardening. The entire surface inside must be smooth and hard, otherwise the core will not fit tightly.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366674_6.jpg)
We measure the internal cross-section of the future magnetic circuit and, using special formulas, calculate the number of turns for the primary and secondary windings.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366665_7.jpg)
We wind the first winding, it is 268 turns according to calculations (for 230 V power supply). But I brought it up to 300 to make some reserve and reduce the no-load current.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366617_8.jpg)
We wrap one turn to another in layers. We isolate each layer.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366675_9.jpg)
The primary winding is ready. We draw conclusions through insulating tubes.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366592_10.jpg)
We insulate in two layers to create reliable galvanic isolation.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366658_11.jpg)
We wind the secondary winding. For a “35 V-0-35 V” output with a total voltage of 70 Volts, it is necessary to wind 84 turns, tapped from the middle.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366639_12.jpg)
We make a tap from the middle, from 42 turns.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366634_13.jpg)
The result was a secondary winding wound with 1.2 mm wire.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366621_14.jpg)
We assemble the transformer core. First, we install “W”-shaped plates in a checkerboard pattern.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366668_15.jpg)
And at the very end, “I” is figurative.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366611_16.jpg)
Checking the transformer. To do this, for safety, we connect the primary winding to the network through an incandescent lamp.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366666_17.jpg)
Everything is working. We measure the voltage at the output of the secondary winding. The result was approximately 32 Volts on each arm.
![Powerful transformer from three low-power ones](https://i.washerhouse.com/uploads/posts/2019-11/1573366648_18.jpg)
In general, the idea is good, the transformer works, does not heat up, there is enough power.
Watch the video
Watch the video for details.