Tachometric Sensor (MEC186E)

This project is from my book Robotics, Mechatronics and Artificial Intelligence (sold out) published in the United States. It shows how to implement a tachometric sensor suitable for mechatronics or robotics projects with microcontrollers or as a building block for simple projects.

The turn-on/off speed of a sensor can be used to measure how fast a robot walks or run or how fast a mechanism moves from one position to other. The circuit shown in Figure 1 converts the on/off frequency of a sensor into a proportional voltage.



Figure 1  -  Tachometric sensor.
Figure 1 - Tachometric sensor.



This circuit can be used to sense the speed of any mechanism, coupling to it a magnet to act on a reed switch or using it to control mechanical contacts. The time constant of the RC network is calculated to give the desired range of voltages in the output as function of the frequency of the input pulses generated by the sensor. The circuit can be powered from 5 to 18 V supplies.