DC electric circuits. Laws of Kirchhoff. Ohm's law for a closed target and for a section of the chain. Methods for calculating linear electrical circuits. Electrical circuits single-phase sinusoidal current. Representation of the sinusoidal function of time by a rotating vector; on the complex plane. Symbolic methods for calculating linear electric circuits of a sinusoidal current. Vector diagrams of voltages and currents. Three phase electrical circuits. Methods of connecting the phase windings of the generator and the phases of the receiver. Semiconductor devices. The conductivity of semiconductors, the formation and properties of the pn junction. Classification of rectifiers. Single-phase and three-phase rectifiers. Smoothing filters. Voltage and current stabilizers.