I have just assembled and am playing with the Tinkerkit Braccio robotic arm: https://store.arduino.cc/usa/tinkerkit-braccio I can move the robotic arm with the braccio library from github. One of my issues is that, after the robot arm achieved its desired position ( e.g. not moving ), the motors …

High pitch noise from servo motors on a robot arm (Tinkerkit Braccio)

jmsjr September 29, 2017, 7:33am 5

MarkT:
PWM driven motors whine. Ultrasonic PWM can reduce/eliminate this.

Silly question ... how does one know if it is a PWM or an ultrasonic PWM motor ?
For example, the list of servos here does not actually indicate it:

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