Cat purr imitation using a motor and a microcontroller.

Cats purr on somewhat 24 - 26 Hz frequency, so to imitate it, I just feed a 24Hz square wave into a motor that has a displaced weight attached to it’s shaft. This is a prototype of a sound effect that we are going to use in our upcomming anti - alarm clock project. All the visible parts except the motor have no use in the circuit, those are just leftovers from previous stuff. The motor is driven from a micro via a mosfet.