This combined text and lab manual covers the basics of electricity and electronics theory. Thoroughly revised, it is designed as an introductory course for electronic service technicians. It is also well suited for use in technical schools as a principle lab manual in typical one-year courses. Emphasis is placed on the commonsense manner of understanding or trouble-shooting circuitry. Experiments, which use commonly available components, are written in a down-to-earth style, so that the student can grasp the most fundamental concepts. Experimental procedures require the student to think and make decisions. Summaries, self-tests and questions are included throughout the text.