GB851046A - Improvements relating to magnetic amplifiers - Google Patents

Abstract

851,046. Magnetic amplifiers. FERRANTI Ltd. March 4, 1957 [March 17, 1956], No. 8404/56. Class 40 (9). A resetting type half-wave bridge rectifying magnetic amplifier has two cores with two windings on each core forming opposite arms of the bridge one diagonal of which contains the load and the other an A.C. source, a further winding being provided on each core, energization of which is differentially varied by a control voltage during half-cycles of the A.C. source of one polarity, the further windings being disconnected during half-cycles of the opposite polarity during which the amplifier gives output. As shown in Fig. 2, the further windings 51, 61 are energized to reset cores A and B by the A.C. source applied to terminals 17 and 18 during half-cycles when the bridge does not conduct. An input voltage across terminals 39 resets the cores differentially to an extent which can be varied by resistor 54. During a half-cycle when the bridge conducts rectifiers 52, 62 disconnect the windings 51, 61. The load 29 is preferably a pure resistance of the same value as resistor 37 in series with the bridge and the A.C. supply. In Fig. 3, an alternative arrangement is shown in which the rectifiers 52, 62 are replaced by triodes, the grids of which are operated in push-pull by the input voltage across resistors 77, 87.