The steady spread of electronics circuits into all aspects of life, but particularly into control technology, has greatly increased the importance of sensors which can detect, as electrical signals, changes in various physical quantities. The range of possible sensors and transducers is now very large, but most textbooks tend to deal with only a few types for specific purposes. In this book Ian Sinclair has described a large range of devices, some for industrial, some for domestic use, some for use only in research laboratories. To make the book useful to as many readers as possible, the physical principles of each device are explained in as much depth as is needed, and the use of mathematics has been avoided unless it is absolutely essential to the understanding of a device. This enlarged new edition includes a new chapter on instrumentation techniques, and new material on A-D and D-A conversion (the latest bitstream techniques), domestic smoke detectors, non-destructive testing of weld integrity, environmental testing etc. The book will be invaluable reading to all engineers and technicians, as well as enthusiasts, who encounter sensors and transducers from the standpoint of specification, design, servicing or education.