your servo motor vid

excellent presentation - Pt 5 stars

 Im a bit confused by dc motor servo (using a pot encoder like sg90) and stepper motor servo. I assume these contain internal bits to process pos fb. either a signal from the pot vs pulse width or counting the number of pulse to infer position - is that right?

What concerns me is the current draw

 lets say a servo arm has to lift a 1kg weight at 1cm (max torque for the sg90). Presumably there is a holding torque needed to maintain position. This could draw 750mA @6v ie 4.5W - presumably the motor can dissipate this heat OK? and it handles the power switching (is there current limiting?

This current draw would be significant in an RC aircraft or a battery powered app

Is there such a thing as a servo with magnetic brake so it draws no power at desired position (Iam thinking of hydraulics where an actuator is locked when the solenoid is closed)

I was inspired (woken up) by your knee arm model

Cheers 10^6

Robin