From the Introduction:

"Electronics books are generally written on one of two levels. When written for the beginner, they are usually so trivial that they do not give enough depth of knowledge to use in practical circuits such as found in avionics equipment. When written to an engineering level, it is typically concealed behind a smokescreen of abstract mathematical gibberish. This book is an attempt to describe electronic devices on a middle level in which we will explain how each device works and why it is important."