The book is devoted to widely used thyristor generators and thyristor inverters underlying many of them for a frequency range of up to several tens of kilohertz. A wide class of circuits capable of operating both at stable and variable load and output frequency is considered. Such devices are needed in various fields of electrical and radio engineering, in particular for ultra-long-wave radio communication, radio navigation, generation of ultrasonic and sonar vibrations. The theory and methods of specific engineering calculation of schemes, taking into account transitional modes, a number of special questions are presented.