4.3 Resistive transducers Resistive transducer a device which converts a measurand into resistance change
• Resistive transducer : a device which converts a measurand into resistance change 4.3 Resistive transducers
4.3.1 Operating principle A Where r= the resistance (2), L= the length of the conductor ) a-the cross-sectional area of conductor(cm p= the resistivity of material&2 cm
A L R = (4.1) where R = the resistance ( ), L = the length of the conductor (c m ), A = the cross-sectional area of conductor ( 2 cm ) = the resistivity of material ( cm ) 4.3.1 Operating principle
4.3. Operating principle Some examples include sliding-contact devices and potentiometers, in which/ changes; resistance strain-gages, in Which L and p change : and thermistors, photoconductive light detectors, piezoresistive strain gages and resistance temperature detectors, in Which p changes
4.3.1 Operating principle Some examples include sliding-contact devices and potentiometers, in which L changes; resistance strain-gages, in which L , A , and change; and thermistors, photoconductive light detectors, piezoresistive strain gages, and resistance temperature detectors, in which changes
4.3.2 Sliding-contact resistive transducers Convert mechanical displacement input into lectrical output, either in voltage or in current This is accomplished by changing the effective length of the conductor by the movable contact The contact motion can be translation rotation or a combination of the two(helical motion in a multi-turn rotation device), this allowing measurement of rotary and translatory displacements
• Convert mechanical displacement input into electrical output, either in voltage or in current • This is accomplished by changing the effective length of the conductor by the movable contact. • The contact motion can be translation, rotation or a combination of the two (helical motion in a multi-turn rotation device), this allowing measurement of rotary and translatory displacements 4.3.2 Sliding-contact resistive transducers
4.3. 2 Sliding-contact resistive transducers Fig. 3.1(a shows a translational R sliding-contact device r=kx (4.2) △x A where k, is the resistance per unit length C - ob and is a constant when the wire is arranged uniformly (a)Translational The transducer sensitivity is Fig. 3. 1 Resistive transducers dR (43)
4.3.2 Sliding-contact resistive transducers Fig. 3.1 (a) shows a translational sliding-contact device. R k x = t (4.2) where t k is the resistance per unit length and is a constant when the wire is arranged uniformly. The transducer sensitivity is t k dx dR s = = (4.3) Fig. 3.1 Resistive transducers