Some years ago I had written a book directed to anyone who designs electronic and electric circuits. Engineers, technicians, teachers, students and hobbyists took a real benefit from that book. The original book is now out of print, being available only used issues. Since the book is very useful, the author decided to review the old edition, add new content and so create a new book for anyone who need a fast access to formulas, tables and calculations when designing his projects or solving a problem. The author, who has himself designed multitudes of projects and circuits during his life, publishing many books and hundreds of articles in electronics magazines and teaching electronics, has collected an assortment of all basic information necessary for calculations needed when designing new projects or solving a problem. More part of these formulas and calculations is now in the author ́s site. The site also has versions in Portuguese and in Spanish. In the site the reader will also find practical examples in projects or articles where many of the formulas shown in this book are used. When starting a project or solving a problem the main difficulty the designer or student founds is how to locate the desired information. This information is normally spread over a large number of resources, such as books, handbooks, Internet, and magazine articles. Although many of us who are experienced in electronics have in mind the principal formulas, we sometimes have trouble with the forgotten constant, multiplication factor or exponent. Finding these values is sometimes difficult depending of the circumstances, such as where you are at the time, or the amount of resources at your disposal.