In this book, the notion of a primary power source will be shown, including an explanation of the many sorts of batteries as well as the relevance of each type. The theory that underpins the thermal generator is explained in the very first chapter of the book. In addition, the photovoltaic cells and the fuel cells are covered in this chapter. The secondary kind of power source is introduced in the second chapter, along with a discussion of the attributes that define it most prominently. After then, a demonstration of the chock transformer follows. In addition, this chapter explains the fundamentals of rectifiers, including the many kinds of rectifiers (half-wave, full wave, three-phase, and controlled rectifiers). In addition, the concepts of filter, smoothing filter, and voltage stabilizer are also discussed. In the third chapter, an explanation is given on the calculation of power supply equipment, including transformers and full wave rectifiers. In the last chapter of this book, the author presents their concluding thoughts on the many issues that were discussed before.