Design of Transistor Vertical Deflection Output and Driver Stages

Television vertical deflection circuits using transistors and direct coupling to the deflection yoke have been described. Although techniques for compensation for the large average flux in the yoke are known they suffer from difficulties with linearity, raster distortion and power consumption. A circuit which uses direct coupling to the yoke requires approximately twice as much power from the battery as does one using a-c coupling to the yoke. This is illustrated in Figure 1 which shows graphically the relative power consumption and its division between the yoke and output transistor. Since power is a prime consideration in a portable television receiver which is to be operated from a battery, a-c coupling is considered an important design objective. To aid in understanding some of the problems involved the circuit requirements of the output and driver stages are studied.