An energizing voltage is series coupled with a diode, an inductor, a flyback transformer primary winding and an input terminal of a deflection circuit. During trace, the diode is forward biased causing a voltage to be developed across and an input current to flow in the inductor. During retrace, opposite polarity retrace voltage commutates off the diode and decouples the input terminal from the energizing voltage at a varied instant within retrace, in accordance with the amplitude of the input current. The amplitude of the input current is related to the ultor load current. A voltage that is indicative of the input current is developed across a capacitor. A DC voltage between one plate of the capacitor and a reference conductor controls the deflection current in the deflection winding such that variations in the ultor voltage produce the same sense variations in the DC voltage that is supplied by the capacitor for maintaining a substantially constant raster width.