Thank you Andrei for helping me on this.
The idea Nisan slider that the “knob” keeps rotation very slow (time*20). But when in movement (keyframes) it moves 1º per pixel. My comp is 500px height. But the idea is when the movement is slow it rotates slow and the movement is fast it rotates fast. Then when stop, keep the rotation (time*20).
But since it is already rotating when is stoped, when start moving it should keep the value of the rotation the you already have to not have a jump.
I hope that make sense.
Thank you again,
Gus