Abstract: An actuating device for a disc brake, in particular for automotive vehicles, has a rotatably supported actuating member and a transforming device for transforming a rotary motion into an axial motion. A part of the transforming device may be held by a holding element whereby the transforming device may be non-rotatable and axially displaceable. The holding element has a rotatably supported part fixed to the brake housing. Friction-reducing means is provided between the rotatable part and the element fixed to the housing.

Abstract: A circuit arrangement for suppressing oscillations, such as acoustic feedback in a hearing aid, has a circuit which recognizes the presence of oscillations in a useful signal, an oscillatory frequency search circuit, and an oscillation modifying circuit controlled by the search circuit. The oscillation modifying circuit suppresses oscillations by filtering. Drift effects are avoided by a frequency clamp-on sub-circuit in the search circuit, which retains the frequency of the recognized oscillation at the modifying circuit, even when the oscillatory signal at the input of the search circuit disappears.