GB244009A - Improvements in or relating to variable electric condensers and the like - Google Patents

Abstract

244,009. Hesketh, B. July 3, 1925. Condensers; transformers.-In a variable condenser of the type in which capacity variation is obtained by varying the distance between two electrically conductive plates, capacity variation is effected by the rotation of a spindle having upon it two threads of different pitch. The plates 1, 2 are carried on insulating blocks 3, 4 respectively engaging threads 6, 7 of different pitch on a spindle 5 which is rotatable relatively to the blocks to vary the distance between the plates. A pin 13 prevents relative rotation between the blocks and has a reduced neck 15 acting as a stop by engaging a pointer 16, an indicating scale being provided such as a circular scale on the top of the block 3 in Fig. 3, or the helical scale 18 in Fig. 1 co-operating with the pointer 18<a>. The plates may be mounted directly on the blocks or on a seating member such as a resilient member 10, and the blocks may be separated by a spring 12. In Fig. 2, the plates are shown as having a hole 19 to admit the pin 13, a lug 20 for screwing to a terminal, and a hole 22 for the spindle 5, the hole 22 being continued as a slot 23, the edges of which are bent up at 24 to engage recesses 25 in the blocks, while the slot serves to prevent eddy currents. In Fig. 3 the block 4 is integral with the body 26 of a radio transformer or the like which the condenser may be adapted to tune.