Tachometers

1. • 
     Tachometers, in their most basic forms, are devices that measure the speed of an object. Most commonly, they measure the rotation of a mechanism, like the engine shaft in a car. Traditionally, tachometers are dials with a needle pointing to the current speed in RPMs (revolutions per minute). However, with the onset of new reading systems, the use of digital tachometers has risen sharply.