Programming and wiring of a low-cost tachometer


  • Rónai László Miskolci Egyetem



microcontroller, rpm measurement, optical sensor


This paper deals with development of a measurement system, which is capable to calculate the rotational speed of a rotor. The unit contains a microcontroller, an infrared reflective optical sensor with resistors. The selection of current limiting resistors of the optical sensor will be discussed in order to set up an electrical circuit. The simulation of the electrical circuit was performed to compare the voltage and current values with the calculated ones. Microcontroller programs were written in C language in order to compute the average frequency or the Root Mean Square (RMS) values of a rotating element. Comparative measurements were also carried out to check the accuracy of the developed system.