Circuit arrangement for eliminating interference influences during the measurement of the mark-to-space ratio of pulse sequences

These pulse sequences are particularly those which are generated by trapping a lightbeam by means of two coaxially arranged rotating discs of an ergometer, characterised by electronics for controlling the pulse heights to a predetermined value. The circuit arrangement also comprises a digital attenuator which is followed by a first comparator which generates squarewave pulses, a maximum-value memory which is followed by a second comparator which decides whether the maximum value of the height of the measured individual pulse is above or below the desired control value, and a feedback device which increments or decrements the attenuator by one step value in accordance with the value of the decision of the second comparator for each pulse.