Screw-driven multiturn electrical device

A screw-driven multiturn electrical device comprising:

• an operating shaft provided with a screw thread in its circumference and having at least one end part provided with a first projection;
• an internally threaded carrying member in engagement with the screw thread of the operating shaft and provided with a second projection that is brought into engagement with the first projection serving as a stopper at the end of the operating shaft;
• and
• a moving member in frictional engagement with the internally threaded carrying member;
• wherein the moving member moves together with the internally threaded carrying member toward the end of the operating shaft when the operating shaft is rotated in one direction to change the level of electric signal, the internally threaded carrying member is turned together with the operating shaft against a frictional resistance exerted thereon by the moving member after the second projection of the internally threaded carrying member has been brought into engagement with the first projection of the operating shaft, and the second projection is separated from the first projection and the moving member moves axially together with the internally threaded carrying member toward an axially middle part when the rotation of the operating shaft rotating together with the internally threaded carrying member is reversed.