GB715296A - Improvements in or relating to methods of widening electric pulses and to apparatus for effecting such widening - Google Patents

Abstract

715,296. Pulse widening circuits. GENERAL ELECTRIC CO., Ltd., FISHER, S. F., and WARD, P. W. April 27, 1953 [April 25, 1952], No. 10478/52. Class 40 (6) A pulse widening circuit comprises a pentode valve to the control grid of which negative going input pulses are applied and which is capacity coupled to the screen grid the voltage of which is prevented from falling below a predetermined value, the anode being coupled to the control grid and positive going pulses being applied to the suppressor grid, widened output pulses being derived from the screen grid. The Figure shows a pulse widening circuit in which a pentode valve 1 has a feedback circuit via transformer 18 between anode and control grid and a rectifier 12 connected to the screen grid and thus preventing its voltage from falling below that applied to lead 13. Negative going input pulses to be widened are applied at 4 via rectifier 3 to the control grid of valve 1 thus reducing the current flow to the screen grid, so that its voltage rises and capacitor 7 is charged, the cathode, control and screen grids of the valve operating as a conventional Miller integrator circuit. When the input pulse terminates rectifier 3 becomes non- conducting and the voltage across capacitor 7 is held until the occurrence of a positive pulse applied at terminal 22, when the suppressor grid voltage rises and the resulting increase in anode current flow through transformer 18 causes the control grid voltage to rise, the effect being cumulative. Capacitor 7 is thus rapidly discharged until the screen grid voltage is held by rectifier 12. Thus each pulse applied at input 4 generates a positive going pulse at output 24 which is terminated by a pulse applied at terminal 22 so that by suitable phasing of these latter pulses a predetermined output pulse width is obtained. Rectifier 25 prevents ringing in the secondary winding of transformer 18 and capacitor 7 may be omitted if the control grid/screen grid interlectrode capacity is sufficiently large to effect the required widening of short pulses. Capacitor 23 and rectifier 14 may be omitted if the voltage applied to terminal 22 in the absence of a positive-going pulse is sufficiently negative.