“This Tachometer very precise. it measures too fast or slow RPMs and it can be used to measure engine RPM or any thing.
I am currently making an electric Bike, but the problem is that I wanted to measure the RPM of the electric motor.
I searched for DIY tachometers online but they didn’t work :(, so I decided to make my own.
Its principal is very easy ; it uses IR Sensor to detect every rotation and then the microcontroller counts the time it took to complete 20 revs and then divides the number of revs over the time it measured and finally multiply it by 60 to give us RPM aka revolutions per minute.”