Bridge Transducers

Abstract

Abstract Bridge transducers depend on a measurand to directly modify some electrical or magnetic property of a conductive element. For example, the thermal coefficient of impedance can result in a change in impedance of a conductive element proportional to temperature. Most bridge transducers, however, depend on the displacement of a flexure to vary the impedance of a conductive element, resulting in an electrical signal proportional to the measurand. Advantage is taken of either the strain pattern on the surface of the flexure or the motion of this surface. Among the gamut of flexure elements associated with bridge transducers are cantilever beams, Bourdon tubes, and clamped diaphragms. Strain gages are used to measure the strain pattern on the surface of the flexure in bridge transducers. It has been noticed that small strains result in small impedance changes in resistive strain gage elements. Electromechanical transducers use a Wheatstone bridge circuit to detect a small change in impedance to a high degree of accuracy. The resistance bridge balance methods have been discussed and it has been found that there are two main types of zero balancing methods which are those that manipulate one arm of a transducer bridge to bring its output to the desired condition and those that manipulate two adjacent arms of the transducer bridge. To obtain measurements of the highest possible quality, one must accurately and carefully calibrate the entire measurement system and various methods such as static calibration, dynamic calibration, and electrical substitution techniques have been illustrated. Finally, all the relevant aspects of resistance bridge transducer measurement system and AC impedance bridge transducers have been summarized comprehensively.