The Physical Effects available for use in Transducers

An interesting three-dimensional representation of transducers was proposed by Middelhoek and Noorlag (1981b), shown in figure 3.1. The primary energy input to the system is represented by the x-axis and the energy output by the y-axis. Self-generating transducers therefore lie in the x–y plane. With the six forms of energy discussed above we have 36 possibilities, of which 30 are true self-generators and six modifiers (having the same form at both input and output). The most important self-generators are the five having electrical output, shown as crosses in figure 3.1; the six modifiers are indicated by small circles.