GB614550A - Improvements in or relating to pulse delay system - Google Patents

Abstract

614,550. Saw-tooth or pulse generating circuits. PHILCO RADIO & TELEVISION CORPORATION. Feb. 6, 1946, No. 3709. Convention date, April 29, 1944. [Class 40 (vi)] A pulse delay system comprises a multivibrator circuit regenerativety intercoupled to produce a single cycle of operation when triggered by a pulse. The load circuit of one valve includes a differentiating circuit from across which an output is taken, the interval between the triggering and output pulses being determined by a cross-coupling between the valves comprising two serially connected time delay circuits, one of which has an adjustable delay. Valve T1 of a cathode-coupled multivibrator is normally cut off and valve T2 isconducting. A positive pulse applied to input terminal 26 causes the grid of T2 to drop in potential to well below its cut-off value. When condensers 21 and 24 have discharged through their shunting resistances sufficiently for the grid of T2 to reach its cut-off value, the valve conducts. When the cut-off value of T2 is reached, normal regenerative action occurs, there is a rapid rise of current through the inductance 12 in the cathode circuit of T2 and a pulse is produced at output terminal 27. The interval between the triggering pulse and the output pulse is dependent upon the time delay of networks 19 and 20 and is adjusted by the setting of potentiometer 14. In a modification, Fig. 3 (not shown), the delay networks are comprised by two condensers in series between the anode of one valve of the multivibrator and the grid of the other valve so that a direct-current path is not provided but such a path is provided between this grid and the cathode of the valve either directly or through a suitable potential source. A variable resistance may be provided in shunt with one of the series condensers.