Instruments

Abstract

The type of meter to be used for a particular measurement depends mainly on the information and accuracy required. The normal pointer-and-scale, or analogue-type instrument, can be produced with good sensitivity at reasonably low cost but there is no doubt that in many applications it is being supplanted by digital-type numerical-display instruments of higher cost and better accuracy. The main source of error in an analogue instrument is the movement itself and for accuracy it cannot compare with the digital types. An analogue instrument of good quality may have an accuracy of ± 1 per cent of the full-scale value, compared with a digital type which can produce an accuracy of 0.1 per cent with ease.