The third edition of this textbook has been updated to include new chapters on audio power amplifiers and power supplies. The book also guides students through the analysis and design of transitor circuits using worked examples and design studies. The new chapters introduce the system concepts of power amplifiers and power supplies and consolidate by example many of the circuit design techniques introduced in earlier chapters. They are particularly concerned with the applications of the material. A wide range of transistor circuitry, both linear and switching, is covered in terms of fundamental qualitative circuit operation followed by analysis and design procedure. This book should be of interest to introductory level undergraduates in electronic and electrical engineering and mechanical engineering.