sduplichan - 2022-07-26

Electric motor speed measurement from the audio spectrum is easy. While many harmonics are present, only the lowest can correspond to a full revolution of the motor.

To demonstrate, I connected a tiny scrap motor from a toy helicopter to a 0-13V power supply. I started recording, then blipped the throttle a couple of times to confirm the motor was working properly. Next, I hit it with 13 volts. The motor is rated for 48,000 RPM (800 Hz) at 3V. The motor actually hit 144,000 RPM before failing. The recording is here. Listen to the file, then view it with spectrumViewer (image).

spectrum of motor test

 

Last edit: sduplichan 2022-07-26