The invention relates to a method and circuitry for continuously evaluating deviations between the measured value and the desired value of a quantity occurring in the form of a sequence of pulses. A counter which functions according to the Aiken code is preset to the complement of a particular desired value, the measured value is fed in the form of a sequence of pulses into the preset counter during a definite interval of time and the difference between the measured value and the desired value is transferred in the form of an Aiken coded number during a second time interval to a memory unit. The Aiken coded number in the memory is then inverted if there has been non-transition through the zero by the counter, the number which is then delivered by the memory being given a polarity opposite to that which would result from a zero transition.