REGULATING CIRCUIT FOR THE MODIFICATION OF A SAWTOOTH SIGNAL

摘要

1521523 Transistor S-shaped sawtooth circuits ITT INDUSTRIES Inc 15 Aug 1975 [16 Aug 1974] 34083/75 Heading H3T In or for a TV receiver, a circuit for distorting a linear sawtooth signal without the use of RC networks for the tangent correction of the vertical deflection current utilizes current controlling circuits which are switched in sequentially so as to modify the charging current of the capacitor across which the sawtooth signal is developed. Generating S-shaped sawtooth waveforms.-In Fig. 1, capacitor C is periodically charged via a first current mirror St1 and discharged via a four-layer diode D. The frequency of the resulting waveform is adjustable at R. The voltage across C is monitored by complementary transistors T31, T32 and compared with reference voltages A31, A32 which respectively determine the times at which further current mirrors St2, St3 feed extra or reduced current via transistor T33 to the input of the first current mirror St1 and so modify the charging current to provide the required waveform. In Fig. 2 (not shown) the first current mirror St1 uses a triple collector transistor with the additional collector and base being coupled to the output of a differential amplifier comprising a pair of transistors. In Fig. 3 (not shown), C is charged via a current mirror comprising two transistors (T53, T54) the voltage across C being monitored so as to control the current supplied by a current mirror (St2) which controls the charging current accordingly.