Powerful microwave transformer power supply

This master class buden is a bit contradictory and will cause more than one scattered opinion. I want to share how to make a powerful rectifier from a transformer with a microwave oven - a power supply unit, for the voltage I need.
Very often, microwave ovens fail and are thrown into the trash. I recently broke another one and I decided to give a second life to her transformer.
The transformer there increases and usually converts 220 V to high voltage 2000-2500 V, necessary for exciting the magnetron.
I have seen many people rework these transformers either for resistance welding or for arc welding. But I never saw him make powerful power supplies.
After all, the transformer is very powerful, about 900 watts, and that's not enough. In general, I'll show you how to rewind the transformer for the voltage you need.

We disassemble the transformer from the microwave oven


Powerful microwave transformer power supply

Usually the microwave transformer contains three windings. The most numerous, wound up with the thinnest wire is an upward, secondary one, at the exit of which is 2000-2500 V. We do not need it, we will remove it. The second winding, thicker, with a smaller amount of wire compared to the secondary, is a 220 V network winding. Also, between these two massive windings, there is the smallest one, which consists of several turns of wire. This is a low-voltage winding of about 6-15 V, giving out the voltage to the magnet of the magnetron.

We cut the seams of the magnetic circuit


Powerful microwave transformer power supply

It is necessary to cut the seams holding together “W” -shaped plates and “I” -shaped. The seams of the Chinese manufacturer are as strong as they seem. You can cut them grinder or even split a chisel with hammers. I used the grinder, it is a humane way.

Remove coils


Powerful microwave transformer power supply

Powerful microwave transformer power supply

Remove all coils. If they are very firmly settled - tap it neatly with a rubber mallet. We only need the winding for 220 V, the rest we delete. We put back the primary winding of 220 V and put it down the "W" -shaped core.
Powerful microwave transformer power supply

Calculation of the secondary winding


Now we need to calculate the number of turns of the secondary winding.For this you need to know the transformation ratio. Usually, in such transformers it is equal to one, therefore one turn of the wire will produce one volt. But this is not always the case and need to double-check.
We take any wire and wind 10 turns of wire onto the core. Then we collect the core and clamp it with a clamp so that it does not fall apart. Be sure to feed a 220 V fuse to the primary winding. And at this time we measure the voltage at the output of the 10-turn coil. In theory, it should be 10 V. If not, then the transformation ratio is not as usual and you need to make calculations to calculate the voltage for your winding. All this is not difficult, mathematics is the fifth grade.
I have two transformers available. One I will do at 500 V, the other at 36 V. You can do at any other voltage.

Winding the transformer coil to 500 V


The transformation ratio of my specimen is one to one. And in order to wind a 500 V winding, I need to respectively make 500 turns of a wire on a coil. Take the wire.
Powerful microwave transformer power supply

Certainly not like that, but coiled up on a drum. We estimate the current and volume of the coil. From these values ​​choose the diameter of the wire.
Powerful microwave transformer power supply

Here is a simple device I assembled for winding a coil.The core itself is made of wood, sidewalls of plexiglas. You can fasten it to a drill or a screwdriver.
Powerful microwave transformer power supply

Wound, collected, connected. I measure the output voltage, almost hit - 513 V, which is acceptable to me.
Powerful microwave transformer power supply

36 V transformer


A winding of 36 V can be wound manually and by taking the appropriate wire. To put on and straighten the winding on the core, you can use such wedges, see the photo.
Powerful microwave transformer power supply

After the winding has completely tightened, into the holes formed, after removing the wedges, put the tightly compressed paper. This is my primitive way. Then I recommend to wrap the winding with epoxy, otherwise it will buzz a lot.

Bug work


I rewound the coil to make it more dense and powerful. For this, I wound it with a double wire, instead of one thick. In the end, I connect them.
Powerful microwave transformer power supply

After all the windings are fixed, it's time to assemble the core of the transformer. To do this, we fix the entire structure with a clamp and weld the same places with arc welding as before. Do not make a thick seam, everything should look like it was.
Next, for my rectifier, I will need:
Powerful microwave transformer power supply

I will load the rectifier at 20 A, naturally the diode bridge must be installed on the radiator.
Also, if you use a metal case like me, do not forget to ground it.

About security


Be careful when connecting the transformer, never take your time and double check everything. Connect the transformer only through a fuse to avoid a possible short circuit. Do not touch live parts while the transformer is running.
Also when processing metal be sure to be careful and use eye protection.

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