A control circuit of a power supply delivering a supply current to an inductor connected in series with the horizontal deflection yoke of a cathode ray tube display, the inductor being the primary coil of a transformer operatively connected for delivering a rectified low-pass filtered biasing voltage to the anode of the display, the low-pass filtering having a first time constant corresponding to the duration of a plurality of pictures, the control circuit having feedback circuitry for generating a monitoring voltage substantially proportional to the biasing voltage and for controlling the supply current to keep the monitoring voltage equal to a reference voltage; and feedforward circuitry for measuring the cathode current and for adding to the monitoring voltage a compensation voltage corresponding to the cathode current, low-pass filtered with a second time constant corresponding to the duration of a small number of lines and high-pass filtered with the first time constant.