TABLE OF CONTENTS Walt Kester
This chapter of the book deals with various sensors and associated signal-conditioning circuitry involving the use of op amps and in amps. While the topic is generally very broad, the focus is to concentrate on circuit and signal processing applications of sensors rather than the details of the actual sensors themselves.
Strictly speaking, a sensor is a device that receives a signal or stimulus and responds with an electrical signal, while a transducer is a converter of one type of energy into another. In practice, however, the terms are often used interchangeably.
Sensors and their associated circuits are used to measure various physical properties such as temperature, force, pressure, flow, position, light intensity, and so forth. These properties act as the stimulus to the sensor, and the sensor output is conditioned and processed to provide the corresponding measurement of the physical property. We will not cover all possible types of sensors, only the most popular ones, and specifically, those that lend themselves to process control and data acquisition systems.
Sensors do not operate by themselves. They are generally part of a larger system consisting of signal conditioners and various analog or digital signal processing circuits. The system could be a measurement system, data acquisition system, or process control system, for example.
Sensors may be classified in a number of ways. From a signal-conditioning viewpoint it is useful to classify sensors as either
