Page 885 - Basic Electrical Engineering

The variation of magnetic coupling between two coils can be utilized to
change M. Displacement of the core or a part of the core can cause change in
M. The change in M will be measured by a bridge circuit and a proportional

signal created for the measurement of displacement.

12.7 POTENTIOMETRIC TRANSDUCER

A potentiometric transducer is basically an electrical resistive transducer. A
potentiometer is an electromechanical device having a resistance element

with a sliding facility which enables changes in the resistance value at the
output. The sliding contact is known as wiper, which may be translatory or
rotary, according to the design. Fig. 12.8 shows potentiometric transducers of

translational and rotational design. Some potentiometers, also called ‘pots’,
are designed combining these two types of motions.

Figure 12.8 Potentiometric transducers. (a) Translational design; (b) rotational design

The output voltage is and in the case of translational

and rotational potentiometer, respectively, as shown in Fig. 12.8. The

resistance element of a potentiometer is excited either by ac or dc voltage.
The motion of the wiper or slider makes a resistance change that may be

linear, logarithmic, or exponential. In Fig. 12.9 are shown applications of