GB644037A - Obtaining a high unidirectional voltage from a electronic oscillation generator - Google Patents

Abstract

644,037. Converting. MURPHY RADIO, Ltd., and KIDD, P. C. Sept. 13, 1947, No. 25138. [Class 38 (ii)] A circuit for obtaining the anode voltage for a cathode-ray tube from a saw-tooth voltage generator, having its anode transformer coupled to a grid, comprises a condenser connected to the anode and grid with a rectifier included in one connection so that the voltages arising on the anode and grid during the flyback period are added and applied to the condenser. A tetrode valve 1 has a primary winding 2 of a scanning transformer in its anode circuit, a secondary winding 3 supplying the scanning coils while another secondary winding 4 applies a voltage to the screen grid, the winding being taken to earth through an adjustable resistor 5 by which the frequency of oscillation may be varied which oscillations may be suitably synchronized by impulses fed on to the control grid of the valve 1. During the flyback period high voltage peaks are generated in the windings 2, 4 which are series connected through .the H.T. source so that the sum of their voltages is applied to a condenser 8 through a rectifier 9, the condenser voltage being fed, by way of a smoothing circuit 12, 13 to the anode of a cathode-ray tube. A further winding 10 may be provided if the voltage for the tube is insufficient. The junction of the transformer windings 2, 4 and not a condenser terminal is earthy and thus minimum effective capacitance is obtained, hence minimum slowing down of the flyback occurs. The elements 12, 13 exert damping effects similar to those of elements 6, 7 which may accordingly be reduced in value or possibly omitted depending upon the size of the elements 12, 13. If the saw-tooth voltage generator supplies the scanning circuit through an amplifier the invention may be applied to the amplifier output transformer (Fig. 2, not shown). The Provisional Specification refers to Specification 643,993.