Abstract: This invention refers to the technical field of electricity. The said transformer caters for present deficiencies of variable transformers, regarding the size of the voltage supplied and its accuracy. The accuracy of the voltage supplied of the modern variable transformers presented gaps usually in the order of 0.5-1.5 V (or higher), whereas the voltage supplied is in the order of 120-130% of the used voltage. The referred variable transformer provides absolutely continuous voltage (without gaps), of any value. Furthermore, if features the advantage, that the intensity supplied to be maintained steady throughout the duration of the supply, for any change of the value of the voltage supplied. The above are achieved, by the exact word, of absolute control of the magnetic flow. Constructively it consists of three half cores core-type (see drawing 1, 2 and 4).