GB445227A - Improvements in or relating to electro-magnetic coils - Google Patents

Abstract

445,227. Inductances. BOSCH AKT.- GES., R., 4, Militõrstrasse, Stuttgart, Germany. May 10, 1935, Nos. 13759, 13760, and 13761. Convention dates, May 14, 1934, Nov. 13, 1934, and Jan. 30, 1935. [Class 37] A high-frequency coil has a coil body of insulating material with which engages a screwthreaded core of finely divided insulated magnetic particles. As shown in Fig. 1, the coil body 8 has internal projections 9 engaging a screw thread moulded on the core 10 so that this may be screwed along for varying the inductance of the coil 11. The projections 9 may consist of guide-pins, of one or more threads, or of depressions pressed in the tube 8 from the outside. In the construction shown in Fig. 2, slots 14, 15 are formed in the tubular coil-carrier 12 in which a wire fork 24, or a U-shaped yoke of hard paper or other insulating material is inserted so as to engage the threads on the core 18, which may be adjusted by inserting a screwdriver in a slot 20. The slots 14, 15 are staggered to correspond with the threads of the screw. The fork 24 may be replaced by one or more springy wire pieces 44,. Fig. 9, bent into not more than a semicircle. The tubular coil-carrier 39 may be inserted into a U-shaped insulating piece 40, into the legs of which the ends of the wire 44 may be secured.