GB595153A - Magnetic amplifiers - Google Patents

Abstract

595,153. Non-contact-making relays. WOOD, N. R., BELL, J., and WOODHOUSE, C. H. L. March 3, 1945, No. 5386. [Class 40 (iv)] In a magnetic amplifier a direct current proportional to the rate of change of the rectified output is superimposed on the input to accelerate the change of input current. Two magnetic amplifiers 1a, 1b, Fig. 3, supplied with A.C. at terminals 4 and controlling D.C. at terminals 8a, 8b have their loads 5a, 5b connected across their rectified outputs. A signal causes one input to rise and the other to fall, so producing a correspondingly increased change in the voltages across loads 5a, 5b. The difference in potential across these loads causes a current to flow through primary windings of transformers 9a, 9b whose secondaries are connected in the respective input circuits, and consequently the input receives an impulse proportional to the rate of change of the output Normal feedback is provided through the coils 7a. 7b. In another embodiment, as applied to a servomotor, Fig. 4 (not shown), the field coils form the loads 5a, 5b and the voltage for the transformers 9a, 9b is obtained from a generator driven by the servomotor spindle. An arrangement in which the impedance across each output rectifier is maintained constant irrespective of loading is described with reference to Fig. 5 (not shown). In this, the two loads are connected as opposite arms in a bridge, the other arms of which are formed by equal resistances of the same magnitude as the load windings. Two such arrangements may be used in cascade.