The modified nut that consists of a lower fixed nut (2) and a rotating shim (5), is being fixed on the threaded collar or other fix part of a potentiometer. The modified nut is only capable of a rotating movement - clockwise or counterclockwise direction depending on the way of assembly of the rotating shim (5) - that is limited by the built-in-stops (3) (6), where the rotating shim (5) can turn from its standstill point in the permitted direction when a force is applied to it, and when such force is terminated it returns to its begining standstill point. To provide the returning force, one end of the pulling spring (4) is attached to the lower fixed nut (2) while the other end is attached to the rotating shim (5). A modified potentiometer knob is fixed to the rotating shaft of the potentiometer (1), this knob consists of an external knob part (7), an internal knob part (9), a pressing spring (8) and a locking cap (10). The internal knob part (9)fixed to the rotating shaft of the potentiometer (1) with (11) grub-screw. The pressing spring (8) creates a pressing force between the internal knob part (9) and the external knob part (7), in pulled up inactive position, there is no connection between the rotating shim (5) and the external knob part (7) can move independently of the rotating shim (5) In switched on active position, it can move connected to the rotating shim (5). When the external knob part (7) can be rotated independently of the rotating shim (5), the rotating shaft of the potentiometer (1) can move between its own minimum and maximum values. The value of the potentiometer set at the moment the external knob part (7) and the rotating shim (5) are connected will be the new minimum or new maximum values of the potentiometer value range.