# Boost autotransformer

Electrical appliances - a fireplace, a kettle, a boiler, a cooker - work well when the mains voltage is 220. 230V. With an increased voltage, they quickly fail, and with a reduced voltage, they reach the desired temperature for a long time. And, as a result, unnecessary costs of both time and energy. It would seem that everything is simple - you need to make a voltage regulator. But here difficulties arise. Electronic regulators can only lower the voltage, and more often, especially in rural areas, it has to be increased. Autotransformer circuits are also poorly suited. All these electrical appliances consume about 1 kW of power. The power of the autotransformer should also be appropriate, since the entire load current passes through its winding. The proposed step controller, the diagram of which is shown in Fig. 1, solves this problem. Here the mains voltage goes to the load, as an additive to which the voltage from the secondary winding of the transformer, connected in series with the mains wires, is used. Each of the 3 secondary windings at Uc = 200 V gives a voltage of 15 V under load (at Uc = 170 V - 10 V) Only the regulation voltage "passes" through the transformer. As a result, a 200-watt transformer at a load of 1 kW can add about 45 V, which, as a rule, is quite enough.

I used a TC-200 power transformer from a black and white TV. It has two coils, and the inclusion of the windings has its own characteristics (Fig. 2). In this scheme, the SA2 switch should be in the middle position. At Uc = 210 V, the regulator usually turns off, so I wound 35 turns from the primary windings (there are 3.5 turns per 1 V in this transformer, that is, I actually "dropped" 10 V). Then he insulated the windings with varnished cloth, and with a PEV wire of 01.5 mm wound 2 secondary windings on each coil (each in one layer, before filling). I put a layer of paper between the windings. It turned out 4 windings of 41 turns. Construction details are located in the case from the network stabilizer. Secondary windings can, with short-term operation, be wound with a wire and thinner (PEV 01.40 1.45 mm). In this case, the transformer practically does not heat up for 1 ... 2 hours of operation.

E. RYABICHKO,