GB582752A - Improvements in or relating to electrical oscillation generators - Google Patents

Abstract

582,752. Pulse generating circuits. STANDARD TELEPHONES & CABLES, Ltd., and LEVY, M. M. March 21, 1941, No. 3881. [Class 40 (v)] Pulses of very short duration of low power and voltage are converted to higher power by a multi-stage amplifier of which the first stage or stages amplify the voltage while the subsequent stages amplify the power but contribute substantially no voltage amplification. The Figure shows a pulse generator in which alternating current of pulse frequency is fed to the input transformer T. Pentodes P1, P2 are fed in phase opposition, a condenser C ensuring that the voltages are slightly displaced from exact opposition. High voltages are supplied through resistances R0 so that sudden saturation is produced, but the positive voltages are limited by the resistances R0 and the negative voltages by the diodes D. In this way short pulses are produced in the common anode resistance Rp and the power consumption in the valves between pulses is reduced by the use of an alternating supply in quadrature with the voltage applied to input transformer T which in addition renders the negative pulses ineffective. The amplifying valves V, V1, V2, are arranged as cathode followers and have an alternating supply to reduce power consumption. Since the operative periods of the valves is only a small fraction of the cycle, plate voltages considerably above those for normal operation may be used, in addition bias arrangements are such that the power dissipation in the periods between pulses is substantially reduced. In addition to the use of alternating current for the anode supply, it may also be used for the screen grids of the same order of magnitude as for normal operation. The valves used are preferably of a type having a high space charge or an emitting surface not exhibiting saturation.