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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Making transformers with your own hands. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Ham Radio Technologies In [1, 2], power transformers at a frequency of 50 Hz were described with their design features and calculation methods. Of course, after calculating the transformer, the required core can, for example, be taken from an old unnecessary or burned-out transformer. Finding the necessary wire for winding the windings of the transformer is also not difficult. But to make a frame for winding windings, to wind them correctly and correctly draw the conclusions of these windings is not easy. Amateurs in the manufacture of transformers use both W-shaped cores and toroidal ones. Transformers on toroidal cores, of course, have a number of advantages in comparison with transformers on E-shaped cores. However, winding windings on toroidal cores in amateur practice is quite difficult: a shuttle is needed, you need to calculate the approximate length of the wire for winding, etc. Therefore, most often amateurs wind transformers on W-shaped cores. The core of such a transformer is assembled from separate W-shaped plates of transformer steel (Fig. 1), which are folded in a certain order.
The required thickness of the set is determined by calculation or using ready-made data. For example, from the calculation it follows that the iron is Sh85 with a thickness of 36 mm, which means that iron is needed from W-shaped plates with a width of the middle part of at least 25 mm and a core with a thickness of at least 36 mm must be typed. A frame is necessarily put on the core of transformer steel, on which the windings are wound. For power transformers, transformer steel plates are assembled as shown in Fig. 2 to obtain a closed magnetic circuit.
When the necessary iron is selected, they begin to manufacture the frame on which the transformer windings are wound. The frame is best made from getinax, fiber, textolite. Start by taking the dimensions of the core: the width of the middle plate and the thickness of the set. Then measure the thickness of the material from which the frame is made. They take a sheet of paper and, drawing on it sketches of the frame parts to be manufactured, write the results obtained on them (Fig. 3).
Double the thickness of the material "p" is added to the width of the core, and the dimension "a" in the sketch is obtained. Next, add twice the thickness of the material to the thickness of the core set, you get the size "b" in the sketch ("c" - the thickness of the material). Then the obtained dimensions from the sketch are transferred to the material. If the material is thin, then the parts are cut out with scissors, and if it is thick, with a cutter. Further, grooves are sawn in the details with a file (needle file). In the first part of Fig. 3 (cheeks), holes are drilled for the leads, then windows are cut through. It is necessary to make six parts of the frame. Two cheeks and two sidewalls (details 2 and 3, Fig. 3). Next, they put the parts on the desktop and assemble the frame (Fig. 4).
If necessary, adjust (file) the locks of the frame parts. Both cheeks are first folded together and fixed on one of the sides, then, having snapped the locks, they are shifted into place. The frame made in this way is strong enough, does not bend during winding and does not deform. After the frame is assembled, its sharp edges are rounded off with a file (needle file), the locks are aligned and all burrs are removed. For greater strength and better rounding, the corners of the frame sleeve are coated with glue. Insulating gaskets are made between the windings, and, if necessary, between the rows (turns) of the windings. For the manufacture of insulating gaskets, thin varnished cloth, tracing paper, thin thick paper, capacitor or cigarette paper, as well as thick cable or wrapping paper are very suitable. A blank of insulating gaskets is made from these materials by cutting strips of the required width with scissors (they should be slightly larger in width than the width between the cheeks of the transformer frame sleeve). This is necessary so that the extreme turns do not fall into the previous layer (Fig. 5).
When winding, the excess edges are slightly trimmed with scissors so that the gaskets do not bubble. The strips are made longer than one turn by about 2 ... 3 cm, then to be glued. In the work, vinyl chloride tubes, pieces of varnished cloth, electrical tape, as well as threads are used to secure the winding leads. When winding windings, it is best to use special winding devices (machines) with a counter for the number of wound turns of wire. Such machines have been published repeatedly in the technical literature, for example in [3]. If there is no such machine, you can use an ordinary hand drill (Fig. 6).
The drill is fixed in a vise attached to the desktop. But in this case, the number of wound turns will have to be counted independently, making marks on paper. A long stud with an M4-M6 thread is fixed in the drill and, with the help of nuts, a frame is fixed for winding the transformer windings. For convenience, a small insert is made from a wooden block (according to the internal size of the frame) with a hole drilled along the axial center, equal to the diameter of the stud. Such an insert allows you to center the frame, which means it is easier and more convenient to wind the wire. Next, they take a piece of a stranded output wire, strip it and, soldering it with a winding wire, make an insulated output (Fig. 7) through an insulating gasket. The output must be wound on a stud so that it does not interfere with the winding of the transformer windings. Then the windings are wound. With the left hand, the winding wire is slightly pulled, trying to lay its turn to turn without gaps.
Between the rows for reliability, insulating gaskets are placed every 500 turns. If necessary, make a tap from a part of the winding, strip the enamel wires approximately 3 ... 5 mm long and solder the tap, then insulate the connection in any way and continue winding. If the winding wire with a diameter of more than 0,35 mm, then it can be used as a lead wire. First, the primary (network) winding is wound, and then all the secondary windings. When the windings are wound, the transformer is assembled (Fig. 2). After assembly, the core is lightly tapped with a mallet so that it aligns. The final operation is the manufacture of a casing from a metal plate. When the casing is ready, they crimp the transformer magnetic circuit with it and install it in place. As a rule, the last core plate does not fit well into the package. To avoid damage to the frame sleeve, in the middle of the core package, two plates are installed on one side, and at the end of the assembly, the last plate is inserted between them from the back side. The last insulating pad on top of the windings is best made from white paper and write on it which windings are in the transformer and their data (the number of turns in each winding and the diameter of the winding wire used for these windings). References:
Author: O.G. Rashitov
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