GB600284A - Electric pulse generating systems - Google Patents

Abstract

600,284. Valve and pulse generating circuits. STANDARD TELEPHONES & CABLES, Ltd. July 19, 1945, No. 18569. Convention date, Nov. 23, 1943. [Class 40 (vi)] A circuit for producing a wave having a constant amplitude characteristic within a wide band of frequencies comprises means for producing an " edger " pulse having leading and trailing edges in which one of the edges is vertical and the other curved, the pulse being applied to shock-excite a damped resonant circuit. As the tuning of the resonant circuit is varied, a pulse of variable width may be produced. The input waveform is fed through a squaring circuit to produce a pulse 56, Fig. 7, which after differentiation by circuit 60 is applied as a short positive pulse 61. to the grid of valve 82, biassed beyond cut-off. Condenser 84 after discharging through valve 82, charges exponentially to produce the " edger " pulse 63 which is applied to shock-excite the tuned circuit 66 to produce a damped train of sine waves. By employing a diode 72, the first negative half-cycle is fed to a pulse-shaping circuit while the succeeding positive half-cycle is suppressed. In a modification, Fig. 8, the pulse 190 or 200, Fig. 9, is applied, without differentiation, to the valve 182 which may operate with zero bias or biassed beyond cutoff. The corresponding output waveforms 191 or 203 have vertical trailing or leading edges respectively, the inductor 186 having the effect of rounding the curved edge of the waveform.