If you are interested in the manufacture of welding machine or voltage regulator, then you definitely need to know what toroidal transformers are. But the most important thing is how they work and what subtleties they have in the manufacture. In addition, such transformers, due to their design, are able to give more power in comparison with those that are wound on the W-shaped core. Consequently, such devices are ideal for powering very powerful equipment — for example, low-frequency amplifiers.
So, before you begin to manufacture a transformer, you need to study the materiel. First, you need to decide on the type of wire used. Secondly, you need to calculate the number of turns (it follows that you will know how many meters of wire you need). Thirdly, be sure to choose the cross section of the wire. This parameter determines the output current, therefore, the power of the toroidal transformer.
It is also necessary to take into account that with a small number of turns in the primary winding, heating will occur. A similar situation arises in the event that the power of consumers connected to the secondary winding exceeds the value that the transformer can supply. The consequence of overheating is a decrease in reliability. Moreover, overheating can even lead to ignition of the transformer.
What is required for manufacturing
So, you start making a transformer. You need to get the tools and materials. Of course, you may even need a sewing needle or matches, but surely everyone has such accessories. The most important thing is the iron from which toroidal transformers are made. You need a lot of transformer steel, it should be in the shape of a torus. Then, of course, wire with lacquer insulation. Be sure to have masking tape and glue type PVA. Also for the separation of the windings necessary tape based on fabric. And a few pieces of wire to connect the ends of the windings. Moreover, the wire must be used in silicone or rubber insulation.
To get such an accessory, as it may seem, is very difficult. But in any house, shed, even at the points of reception of the metal today you can find unusable voltage stabilizers. In the Soviet years, they were very popular, used together in black and white TVs, so as not to put the picture tubes. It doesn't matter to you whether this stabilizer is working or whether it has burned down. The most important thing is the toroidal transformers that are used in it. They will be the basis of your design. But before that you need to get rid of the old winding, which is made of aluminum wire. And then - the preparation of the core. He has right angles. You do not need it, because you can damage the lacquer insulation during winding. Try to round the corners with a file. Then, on top of transformer steel, lay the tape on the basis of the fabric. All you need is only one layer.
And now a little about how to calculate the toroidal transformer. You can, of course, use simple programs, of which there are a great many. You can make a calculation with a ruler and a calculator. Of course, it will have an error, since it does not take into account many more factors that are generally present in nature. You should follow one rule when calculating - the power in the secondary coil should not be greater than the same value in the primary winding.
As for such a process as winding a toroidal transformer, it is very laborious. It is good if there is an opportunity to disassemble the magnetic core and, after winding, assemble it together. But if there is no such possibility, then a kind of spindle can be applied. On it reel a certain amount of wire. Then, passing this spindle through the torus, lay the turns of the windings. It will take a lot of time, so if you are not confident in your abilities, you'd better get a ready-made power supply.
It is best to describe the process with a specific example. The primary winding, as a rule, is powered by an AC voltage of 220 V. Suppose you need two secondary windings, so that each of them produces 12 V. And you also use a 0.6 mm wire in the primary winding. Consequently, the cross-sectional area will be approximately 0.23 square meters. mm But this is not all calculations, toroidal transformers need careful adjustment of all parameters. And now again a bit of mathematics - you need to divide 220 (V) by the sum of the voltages of the secondary circuits. As a result, you get a certain coefficient of 3.9. It means that the cross section of the wire used in the secondary winding should be exactly 3.9 times larger than the primary one. To calculate the number of turns for the primary winding, you need to use a simple formula: multiply the “40” coefficient by voltage (in the primary circuit it is 220 V), after which this product is divided by the cross-sectional area of the magnetic circuit. It should be noted that how accurately the toroidal transformer is calculated, its efficiency and service life depend. Therefore, it is better once again repeat each step of the calculation.