This textbook presents a thorough exploration of DC power supply systems—vital components in modern electronics. Designed for engineering students and electronics enthusiasts, it bridges theoretical concepts with practical applications through a structured approach. The book features interactive simulations using Falstad, allowing hands-on learning without physical components. Self-assessment tools and practical exercises reinforce understanding throughout.By the end of this journey, readers will possess the knowledge to design, troubleshoot, and optimize DC power supply circuits—an essential skill in today's technology-driven world.