Improvements in and relating to thermionic valve circuits such as multivibrators and the like

Abstract

Abstract 528,806. Valve generating circuits. CALVERT, R. May 5, 1939, No. 13518. [Class 40 (v)] A multi-vibrator or like circuit comprises two resistance-capacity coupled valves V1, V2, Fig. 2, having a common resistance Rc traversed by the space current of both valves and common to the control grid-cathode circuits of both valves. Fig. 3 shows a similar circuit used as a frequency divider, resistance 11 corresponding to resistance Rc in Fig. 2. The controlling signals are applied from circuit 13 to the grid of valve V1. The anode-cathode impedance of valve V1 is reduced by a negative feed back circuit 18, 16 between the anode and grid of that valve. A variable resistance 10 permits adjustment of the duration or width of the generated pulses, the frequency of which is adjusted by resistance 27. The controlling or locking signals applied to circuit 13 may be automatically varied in amplitude in accordance with fluctuations in the supply voltage by deriving such signals from a valve fed from the same source, and operating on the anode current limitation. A plurality of multivibrator circuits may be connected in cascade without the interposition of a separator stage, the second valve of each multivibrator operating with anode current limitation. The controlling pulses should be peaked pulses such as are obtained by applying square pulses to a condenser and resistance in series. The natural frequency of oscillation of the multivibratior is preferably below the frequency of the controlling impulses and is pulled up in frequency thereby.

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