Author Simon Monk (Raspberry Pi Cookbook) breaks down this complex subject into several topics, from using the right transistor to building and testing projects and prototypes.
Simon Monk is a full-time author and maker, mostly writing about electronics for makers. Some of his better-known books include Programming Arduino: Getting Started with Sketches, Raspberry Pi Cookbook, and Hacking Electronics. He is also the co-author of Practical Electronics for Inventors and wrote Minecraft Mastery with his son, Matthew Monk.