Contact-Less Digital Tachometer with 99kRPM

The project describes the construction of a contact-less tachometer by using a 8051 microcontroller and a proximity sensor to be used in counting the revolutions per minute of a rotating shaft.

The device has been made special because it can measure very accurately the rotational speed of a shaft without even touching it. This is very interesting when making direct contact with the rotating shaft is not an option or will reduce the velocity of the shaft, giving faulty readings. An AT89S52/AT89C52 microcontroller is used to build the device along with an alphanumeric LCD module and a proximity sensor to detect the rotation of the shaft whose speed is being measured. Before the device needs to be charged, a 600mAh NiCd battery will provide months of regular use.

The design was constructed using an IR signal to transmit and receive it reflected from reflective stripe fixed to rotating shaft. The reflected pulses are counted and the value is displayed on LCD. RPM counting algorithm uses last three times between pulses and this way constantly gives instant RPM value. There are two parts the comprise the RPM including microcontroller board and IR proximity sensor.

Rest of the project