GB562598A - Improvements relating to electrical recording apparatus - Google Patents

Abstract

562,598. Recording electrical measurements. SIEMENS BROS. & CO., Ltd., and TURNER, F. Dec. 31, 1942, No. 18569. [Class 40 (i)] Electromagnetic unbalance of a circuit due to small movements, e.g. torsion in a shaft are recorded by apparatus driven simultaneously with a differential transformer arrangement for effecting rebalance. The nature of the electric circuits is shown in Fig. 1 wherein a member C1 connected at one point on shaft S carries a pair of transformers T3, T4 having primaries P3, P4 in series with a current source and secondaries S3, S4 connected in opposition in a control circuit, the magnetic circuits of the transformers being varied in opposite senses by a bridging member H2 carried at another point on the shaft and providing variable gaps. The re-balancing is effected by a second similar pair of transformers T1, T2 the resultant secondary output of which is adjusted to balance the secondary output of the first pair. The current source may be alternating but, as shown, D.C. is used in conjunction with an interrupter ISP, the secondary circuit being interrupted on alternate half cycles at ISS to provide pulsating D.C. in the circuit. Out of balance current operates PR which energizes one or other of the electro-magnets ASM, AHM. The recording apparatus shown in Fig. 2 comprises a unidirectional driving motor EM which operates the interrupters ISP, ISS and drives a shaft L and bevel pinion LC. The recording stylus S is driven by a screw shaft SS driven in one or other direction from a shaft SCS which has diametrically opposite bevel pinions selectively engageable with pinion LC by the out-ofbalance magnets ASM, AHM. The screw shaft SS is also coupled to screw FDS which adjusts the bridging member H1 of the rebalancing transformers T1, T2. The record strip C is driven through a friction clutch FC from shaft L by variable speed gear trains. A finger knob may be provided for driving shaft SS by hand if the motor or source of power fails, the position of the stylus being read on a scale SCE. Specification 166,317, [Class 37], is referred to.