GB633884A - Improvements in or relating to the synchronisation of oscillation generators - Google Patents

Abstract

633,884. Pulse frequency dividing circuits. CINEMA - TELEVISION, Ltd., and ELBOURN, R. W. May 22, 1947, No. 13807. [Class 40 (vi)] In a cathode-coupled multivibrator circuit used as a frequency divider the synchronizing signals are applied via a rectifier to the grid of one of the valves to oppose the steady bias potential at the grid. Fig. 1 shows a multivibrator comprising valves 1, 2, the synchronizing signals being applied via valve 15, differentiating circuit 13, 12 and diodes 10, 11 so that the sawtooth waveform of the synchronizing voltage, Fig. 2 (d) (not shown) at the grid of either valve is such that the multivibrator synchronizes at an even sub-multiple of the synchronizing frequency with the phase of the sub-multiple frequency corresponding closely to that of the synchronizing frequency. The synchronizing signals preferably have an amplitude S determined by the equation S=2V/n where V is the voltage excursion of the grid of the valve to which the synchronizing signals are applied and n is the ratio of the synchronizing signal frequency to the free-running frequency of the multivibrator. In a modification, Fig. 3 (not shown), the synchronizing signals are applied to an amplifier and outputs are taken from both the anode and cathode loads and are applied via differentiating circuits and diodes to. the grids of both multivibrator valves. This circuit may be used when division by an odd number is required. In a further modification, Fig. 5 (not shown), the grids of the multivibrator valves are normally negatively biassed the synchronizing signals being applied via diodes to give a positive signal at the grids. In another modification, Fig. 6 (not shown), the grids of the multivibrator are biassed positively and negatively respectively and the synchronizing signals are applied via diodes poled so that the synchronizing signals applied to the grids oppose the standing bias.