In industries, machinery and devices, the speed of rotating part or motors needs to be measured to monitor or to control the system especially in servomechanism. Tachometer is an instrument which is used to measure the rotation speed of a shaft or disk, as in a motor or other machine. It measures the rotational speed in the unit revolution per minute (RPM). This paper provides a detailed study on the design and development of contactless tachometer based on different techniques. First design of a simple, easy to implement magnetic type Reed relay based tachometer, Second design of Hall sensor based tachometer and finally IR based tachometer by using low cost linear digital integrated circuits (ICs). We have developed a model which counts the rotation using different sensor techniques and analyzed for the sensitivity for handling speeds with vast range of rpm. With the help of a microcontroller speed can be calculated and displayed.

Servomechanism, tachometer, RPM, Reed relay, Hall sensor

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