An operational amplifier circuit is for an arc fault circuit interrupter including a current sensor having a secondary and an envelope detector circuit having an input. The ends of the inner elements have a greater cross-section than the region lying between said ends and at least one of the ends is elastically embodied for a temporary reduction in cross-section. An intermediate chamber is formed between the shield and the first cooling stage, and the base of the shield is connected in a thermally conductive manner to the first cooling stage by means of a thermal bridge. The speed information detection circuit is configured to detect speed information before or after an interruption of a recording on the optical disk based on the electrical signal from the optical pickup.