GB228267A - Improvements in electric inductance coils and in formers therefor - Google Patents

Abstract

228,267. Evans, E. C. W. Nov. 1, 1923. Inductances. - Tuning coils for wireless apparatus and other electric inductances comprise a singlelayer coil of wire supported upon, and spanning the gaps between, longitudinal ridges or upstanding points provided all around and along the surface of a hollow cylindrical former, the wire being wound saliently on the former to stand out therefrom so that each turn is separated from the former and from adjacent turns by air spacing, thus reducing capacity effects and facilitating the connection of tappings to the coils. The former may be carved or moulded from hardwood, fibre, or ebonite, or formed from millboard. Slots 6, Fig. 5, may be carved or moulded to receive longitudinal, projecting, insulating slips 7 inserted edgewise and supporting the coil, or the slips 7 may connect and be slipported on internal spaced insulating rings to form a skeleton former. In modifications, projections 4, Fig. 3, support the coil 5, or a hollow cylinder 1, Fig. 6, is surrounded by a sleeve 3 with longitudinal hollow corrugations, which may be pointed, as shown, or rounded, the tops of the corrugations supporting the wire and the bottoms resting on the cylinder. The space between two adjacent ridges or rows of upstanding points may be filled in with insulating material or left solid to provide a flat surface 9, Fig. 6, supporting the wire under the slider of a variable inductance, and the ridges or upstanding points may be provided with shallow notches, such as 8, Fig. 3, to receive the inner sides of the turns of wire and so hold them in position.