How to measure motor rpm with oscilloscope?

Thread Starter


Joined Oct 12, 2019
Hello, I'm working on a college project where we need to verify a 3-phase (rc airplane) motor's rpm using an Oscilloscope. I already found this video on how to hook up an ESC to it which is great. But how do i read this data to calculate the motors rpm? Any help would be great, I'm new to Oscilloscopes.



Joined Jul 18, 2013
Set up the artificial GND as per the video, but if only requiring rpm, then only one phase is needed, first you need to know or detect the pole count.
This is done by first shorting all three outputs and rotating the shaft one revolution by hand and counting the number of 'bumps'.
This is the pole count, which is then divided unto the detected-measured frequency on the scope when the motor is ran under power.