Device for regulating the electric feeding of a charge (1) through the alternating current, with at least some serially opposed switching elements (3) or a switching network, and a unit for controlling (2) said switching elements (3). The device comprises a comparator (5) of the saturation voltage "V CEsat " of the switching elements (3), associated to an attenuation network (8) in an input terminal, insofar as in the other input terminal there is a voltage generator having the reference "V ref " disposed between the collector and emitter "V ce " corresponding to an "I ce " current equal to zero, in order to determine the moment of null circulation and current due to said switching elements (3) through the fall of "V CEsat " below "V ref ", determining a current zero-crossing signal to the control unit (2).