GB957882A - Improvements in or relating to time-base circuit arrangements - Google Patents

Abstract

957,882. Sawtooth generating circuits. PHILIPS ELECTRICAL INDUSTRIES Ltd. Aug 14, 1962 [Aug. 17, 1961], No. 31163/62. Heading H3T. [Also in Division H2] In a circuit for generating a sawtooth wave in a coil, operating in the so-called " flyback driven " manner (see, for example, Specification 821,517) the output transformer is so arranged as to minimize the magnetization of the core. A typical basic circuit comprises a capacitor C 1 which is charged during the long stroke from a supply Vb through a preferably large impedance L 1 . To produce the flyback a controlled rectifier T is rendered conductive and the energy of the capacitor is resonantly transferred to the inductive output circuit comprising deflection coils Ls, the output transformer 2 and an " overawing " coil L 2 . When the oscillation in the resonant circuit reverses diode D becomes conductive thereby clamping the voltage across the inductive system so that a linear long stroke occurs as the indictive energy is returned to the supply and as the capacitor C is charged again through L 1 . If the circuit is rearranged as shown in Fig. 2 the turns ratios may be selected so that the mean magnetization of the transformer core is zero. The winding n 1 may be formed as two parallel windings carrying charging and feedback currents respectively and provision may be made to generate an E.H.T. voltage, in which case adjustment of the turns ratio is necessary to maintain the mean magnetization small. In Fig. 8 (not shown) the circuit is modified to provide a series " B boost " while in Figs. 9 and 10 (not shown) the circuit is rearranged to effect a further reduction in the mean magnetization. Specification 949,535 also is referred to.