Abstract: The pulses of an output pulse train are made to conform to a desired duty cycle within the limits afforded by the individual cyclical periods of an input pulse train by digitally measuring each input cyclical period to afford a digital counting interval indicative thereof and providing during the next successive cyclical period a traversal of the digital counting interval in a time corresponding to a predetermined percentage (desired duty cycle) of the measured period. Each output pulse is initiated after the transpiration of a predetermined period of time from the onset of each input pulse and terminated upon the earlier completion of the cyclical period for that input pulse or the digital counting interval initiated during that period.