Patent GB-839051-A (GB)
Title: Improvements in or relating to power supplies
IPC: H03F9/00
Filed: 1957-09-24
Abstract: 839,051. Magnetic amplifiers. INTERNATIONAL COMPUTERS & TABULATORS Ltd. Sept. 24, 1957 [Sept. 26,1956], No. 29969/57. Class 40 (9). A source of alternating power pulses applies complementary pulse trains VL, LH, Figs. 1 and 2, to the control and output windings 16, 17 of a resetting-type magnetic amplifier 27 over rectifiers 15, 21, each pulse train comprising pairs of alternating pulses extending over time periods t1, t2 which are spaced apart by dwell or zero potential periods t3. The provision of dwell periods t3 permits the pulse repetition frequency to vary without altering the time periods t1, t2 and thereby influencing the amplifier operation. As shown, the two pulses forming a pair are separately produced by pulse sources 11 and 12 which function in the time periods t1 and t2 respectively. A synchronizing link ensures that both sources are inoperative during the dwell periods t3. After amplification by pentodes T1, T2, the pulses are applied to the centre-tapped primary winding of a step-down transformer 13, the winding portions 18 and 19 being each shunted by a damping resistor. The transformer secondary winding is also centre-tapped, and is biased by a potential 30 so that the pulse trains VL and VH induced therein are asymmetric. The amplifier operates in the usual manner by reversal of its saturating flux in time periods t1 and t2 when its windings 16, 17 are alternately energized. As these windings are each connected in series with a resistor 22, 23 to a source of positive potential B3, negative output pulses VOUT are produced at terminal 25 in time periods t2 in response to negative input pulses VIN at terminal 14 in time periods t1, these input pulses inhibiting resetting of the core. Earth potential inputs on the other hand permit full resetting of the core, and corresponding earth potential outputs are obtained in periods t2 at the output terminal since the impedance of winding 17 is high and clamping rectifier 24 conductive. A further arrangement is disclosed, Figs. 3 and 4, in which amplifiers 56, 71 are connected in cascade so that an output VOUT (DIRECT) is obtained at terminal 77 corresponding to the input VIN at 65, while an inverted output VOUT (INVERTED) is developed by transformer action in an auxiliary winding 82. The two amplifiers are energized by respective pulse trains V1L, V2H and V2L, V1H which are obtained from transformers 45, 52, the primary windings 46, 53 being supplied from synchronized pulse sources 31-34 by way of pentodes T1-4T. Both arrangements use consecutive pulses of dissimilar duration, and in the Fig. 3 embodiment the pulse periods of the two pulse train groups V1L, V2L and V2L, V1H have respective durations t1, t2 and t4, t5 over the same time interval. In operation, an input VIN is applied to amplifier 56 in period t1 and is read out in period t2, this output immediately constituting the input to amplifier 71 within time period t5. After a dwell period t6, the outputs at terminals 77 and 85 are developed in period t4A. This circuit includes resistors 63, 64, 67 in series with the amplifier windings, and utilizes clamping rectifiers 66, 76, 84 to earth the respective output paths when negative output pulses are not produced.