Powerful power supply from a microwave transformer
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 microwaves fail and are thrown into the garbage bin. I recently broke one more and I decided to give a second life to its transformer. The transformer there is a step-up and usually converts 220 V to high voltage 2000-2500 V, necessary to excite the magnetron. I have seen many people convert these transformers or under the apparatus for resistance welding, or apparatus for arc welding. But I have never seen a powerful power supply unit made of it. After all, a transformer is very powerful, about 900 W, and this is not enough. In general, I will show you how to rewind a transformer to the voltage you need.Usually a 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 less wire than the secondary, is a 220-volt mains. Also, between the two massive windings, there is the smallest, 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.It is necessary to cut down the seams holding "Sh" -shaped plates and "I" -type. The seams of the Chinese manufacturer are not as strong as they seem. They can be cut by a Bulgarian or even chipped with a chisel with hammers. I used a grinder, this is a humane way.Remove all coils. If they are very firmly seated - knock gently with a rubber hammer. only the winding for 220 V is useful, the rest are deleted. We put back the primary winding for 220 V and place it downward of the “W” -shaped core.Certainly not the same, but coiled up on a drum. We estimate the current and volume of the coil. From these values choose the diameter of the wire.I assembled such a simple device for winding a coil. The core itself is made of wood, the plexiglass sidewalls. You can attach it to a drill or screwdriver.Wound, assembled, connected. I measure the output voltage, almost hit - 513 V, which is acceptable for me.After the winding is all taut, put the tightly pressed paper into the holes, after removing the wedges. This is my primitive way. I recommend to impregnate the winding with epoxy, otherwise it will be very humid.After all the windings are fixed, it's time to assemble the transformer core. To do this, we fix the entire structure with a clamp and weld the same places with arc welding as before. To make a thick seam is not necessary, everything should look like it was. Next, for my rectifier I will need:I'll load the rectifier by 20 A,Naturally, the diode bridge must be installed on the radiator. Just like, if you use a metal case like me, do not forget to ground it.