- - _vane \: y;) \ c: =:: J ] 0=0 ] Dc: =JD Fig. 2. 39
Seven-segment devices for large displays and good visibility at up to
300 m can readily be obtained. Summary The number of transducer types is
almost unlimited, and in order to bring our area of study down to a more
manageable size we have considered transduc- ers under four main
headings. Input transducers for detecting mechanical change allow us to
sense force, pressure, position, proximity, displacement, velocity,
acceleration, vibration and shock in all their multiple manifestations.
The basis of many mechanical sensors is the strain gauge which is
usually used in a bridge configuration. Other devices such as the L VDT
and synchro are also widely used. Temperature transducers form another
large group, and we have looked at the operating principles of the major
types, with some of the techniques used in compensating for non-ideal
characteristics. Radiation and chemical sensing transducers form the
remaining groups. Actuators rely almost entirely on electromagnetic
action and, in modern equipment, occur most commonly as solenoids and
relays, including the reed relay, and stepper motors. Visual displays
also come in a bewildering range of types and sizes, but, because of
their ease of interfacing with electronic circuitry, the majority are
based on the LED and LCD. Review questions 1. What is meant by gauge
factor? 2. Define Young's modulus. 3.
