GB448927A - Improvements relating to the control of alternating currents - Google Patents

Abstract

448,927. Telegraph transmitters. HARRIS, L. H., 5, Phillimore Gardens, Kensal Rise, London. Oct. 17, 1934, No. 29645. [Class 40 (iii)] An alternating-current transmission line A, B, Fig. 1, is bridged by the primary 1 of a transformer, the secondary winding 2 of which is connected through a condenser 5 across the diagonal a, b of a bridge of non-linear conductors, e.g. dry-plate rectifiers, across the other diagonal c, d of which is connected a D.C. control circuit so arranged that the secondary 2 is effectively short-circuited when the point d is rendered positive relative to the point c. Thus, D.C. signals applied across the diagonal c, d key the alternating currents in the line. For double current D.C. signals a further bridge e, y may be provided so that the check meter M in the D.C. circuit may read zero. The second bridge may control in the opposite sense a transformer connected in series in the line, Fig. 3 (not shown). In another embodiment, Fig. 2, a single bridge controls in opposite senses series and parallel transformers 1<1>, 2<1> and 1, 2 respectively in the line A, B. A further embodiment, Fig. 6 (not shown), comprises a unit designed to replace a known type of keying relay, and which can be connected to a jack to be interchangeable therewith.