This book is written for a wide range of pre-degree courses in electronics. The contents have been care- fully matched to current UK syllabuses at Level 3 / A-level, but the topics covered, depth of coverage, and student activities have been designed so that the resulting book will be a student-focused text suit- able for the majority of courses at pre-degree level around the world. The only prior knowledge assumed is basic maths and the equivalent of GCSE Double Award Science. The UK courses covered by this text BTEC National Engineering Pathways syllabus (2007), Units 5 (Electrical and Electronic Principles), 35 (Principles and Applications of Electronic Devices and Circuits), 62 (Microprocessor Systems and Applications), and the introductory stages of Units 51 (Industrial Process Controllers), 60 (Principles and Applications of Analogue Electronics), 68 (Principles and Applications of Microcontrollers), and 90 (Telecommunications Principles). A-level (AS and A2) specifications from AQA, OCR and WJEC. The book is essentially practical in its approach, encouraging students to assemble and test real circuits in the laboratory. In response to the requirements of certain syllabuses, the book shows how circuit behav- iour may be studied with a computer, using circuit simulator software. The book is suitable for class use, and also for self-instruction. The main text is backed up by boxed-off discussions and summaries, which the stu- dent may read or ignore, as appropriate. There are frequent ‘Self Test’ questions at the side of the textwith answers given in Supplement B. Numeric answers to other questions and answers to the multi- ple choice questions are on the companion website. The text has undergone a major revision to pro- duce this fourth edition. Additions to the content include five new Topics. These cover electrical and magnetic fields, diodes, oscillators, integrated circuits, and industrial process control systems. Several other Topics have been expanded, to reflect the increasing importance of digital electronics and microcontroller systems. All Topics have been updated where neces- sary, to keep pace with the many recent developments in electronics. The ‘On the Web’ panels in many Topics are a new feature of this edition. They are intended for stu- dents to make use of the wealth of relevant informa- tion available from that source. Also, this edition coincides with the launching of a companion website. This has a PowerPoint presentation of illustrations from the book for use by students and lecturers. It has the answers to numeric questions and to all the multiple choice questions. There are many more of these in this edition. There are pages of worked examples and questions for those who need extra sup- port in maths. The companion website also includes some novel a set of calculators for electronic formulae, animated diagrams to show electronic circuits in action, and series of interactive worksheets, with answers.