| 摘要 |
1,181,145. Supply systems for A.C. loads. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 10 May, 1967 [13 May, 1966], No. 21783/67. Heading H2H. A circuit for firing a pair of controlled rectifiers e.g. thyristors Th 1 , Th 2 connected-to voltages of opposed phases comprises a centre tapped transformer having outer windings PB, PB1 in phase opposition, each part having a 90-degree phase-advancing CR circuit e.g. 1, 2 connected to a diode 4. The base-emitter circuit of a transistor T 1 is fed with the sum of this voltage, an in-phase voltage from a resistor 5 developed by a diode 3 and a D.C. control voltage F, H. Transistor T 1 is biased by resistors R8-R10 which connects the input voltage into a square wave by driving the transistor into saturation. The stage incorporating transistors T 2 , T 3 is arranged to be oscillatory developing say 2 kc/s. and supply through a transformer Ue having duplicate primary and secondary windings, the rectifier gating circuits. The middle winding between taps B, B<SP>1</SP> may be omitted, taps B, B<SP>1</SP> then being coincident - with tap A. |
