GB810898A - Improvements in or relating to rectifying circuit arrangements - Google Patents

Abstract

810,898. Rectifying. PHILIPS ELECTRICAL INDUSTRIES Ltd. March 7, 1957 [March 10, 1956], No. 7587/57. Class 38 (2). For supplying a D.C. load such as theatre lighting with current of different intensities, the change from one value to the other being made gradually, two grid-controlled high-vacuum valves 2, 3 are connected in bi-phase to a transformer 1 and have connected to their grids two circuits in parallel. These comprise respectively rectifier valves 10, 11 connected in antiparallel, in series with variable resistors 12, 13 and connected together at their other ends to a selector switch 18 which makes contact with any one of two or more tappings 15, 16 on a resistor 17 connected across the output terminals. With switch 18 connected to contact 15, capacitor 8 is charged to a comparatively low value, the grids of valves 2, 3 receive a low negative voltage and the rectifier output is high. When switch 18 is moved to contact 16, capacitor 8 is slowly charged to a higher value through valve 11, the grid voltage goes to a greater negative value, and the rectifier output slowly decreases. When the switch is reconnected to contact 15, condenser 8 discharges through valve 10, the rectifier output slowly returning to its original value. The rate of change of load current is varied by altering the value of resistors 12, 13. Abrupt change of load may be obtained by reducing one or both resistances 12, 13 to zero or short-circuiting the parallel circuits. Load intensity may be controlled'by a variable tapping on' resistor 17 (Fig. 2, not shown).