Improvements in pulse generating circuits

Abstract

Abstract 666,575. Converting. BRITISH THOMSON-HOUSTON CO., Ltd., & MELVILLE, W.S. Nov. 15, 1949 [Nov. 15, 1948], No. 29614/48. Class 38 (ii). An electrical circuit comprises a saturable cored inductance P connected in series with a substantially resistive load R, the combination being connected across a capacitor C or a capacitance network which is adapted to be charged through an inductance L from an alternating supply, the circuit constants being of such values that saturation of the core causes the charged capacitor or charging circuit to discharge through the load and produce a pulse of energy therein, the charging circuit being resonant at the frequency of the supply. When the voltage across the capacitor reaches a peak value the inductance P becomes suddenly saturated and a pulse is supplied to the load. Thereafter the inductance P becomes unsaturated and the capacitor is re-charged to produce a pulse in the opposite direction. The circuit may be used with a phase-shifting device and a pulse transformer arranged to control the output of a full-wave rectifier system comprising discharge valves, Fig. 3 (not shown). Rectifiers may be included in series with the grids of the discharge valves. When the discharge valves are required to maintain the output voltage constant despite fluctuations in supply and load, the necessary control may be obtained by varying the amplitude of the supply voltage to the saturable reactor circuit. The system may be used to generate pulses of double exponential form, Figs. 5a, 5b (not shown). A condenser/resistance element is then added to the circuit to delay both the rise and fall of the current-pulse. When it is desired that each pulse is of the same polarity, a second winding is added to the inductance P and is supplied with direct current to provide a biasing flux in the core, Fig. 4a (not shown). The capacitor C may be charged through a step-up transformer N (Fig. 7a), biasing flux in the core of the inductance P being derived from condenser M which is charged from a direct current source, provided with a de-coupling inductance S. Other methods of biasing this circuit are shown. The capacitor C may be connected in a T- network between inductance P and another saturable inductance, the unsaturated inductance of which is substantially larger and the saturated inductance substantially smaller than the unsaturated value of P, Fig. 6 (not shown). A higher rate of rise of current in the load is thus obtained. This arrangement may be used for firing two ignitrons in turn. The saturable inductance cores may be constructed of material having a substantially rectangular hysterisis loop, such as 50-50 cold rolled nickel iron. Specification 666,574 is referred to.

Inventors

No inventors recorded.

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