GB234570A - Improvements in or relating to variable inductances - Google Patents

Abstract

234,570. Bell, L. H. Bainbridge-, and Radio Communication Co., Ltd. March 13, 1924. Inductances.-The inductance of a coil of approximately cylindrical form is varied by deformation against its own resilience or that of a former on which it is wound by pressure applied at rightangles to its axis. In the apparatus shown in Fig. 1 (12203/24), a coil 6 of pointed oval form is mounted between insulating plates 1, 2, the distance between which is variable by means of a screw 4 engaging a nut 5 embedded in the plate 2. The screw is provided with a knob and pointer. A scale parallel to the screw may also be provided. The coil may be compressed until the opposite sides meet. The coil is preferably in two sections one on either side of the screw 4. In a modification, each of the plates 1, 2 is provided with a groove to receive an insulating strip secured to the coil. The strip may be secured to we plates by screws. In another modification, the plates have undercut grooves in which are slid dove-tailed strips secured to the coils. The strips may have extensions serving as handles. Metallic strips connected to the ends of the coil may be embedded in the insulating strips to make contact with studs in the grooves. In the modification shown in Fig. 1 (13587/24), the coil is attached to ribbons 6 which are screwed to insulating plates 7. The plates 7 are provided with bosses 8 pivotally mounted on pins 15 secured to toothed sectors 11 pivoted at 9 to a base 10. The sectors 11 engage a pinion 12 mounted in the base 10 and a strap 3. The pinion 12 is operated by a knob to adjust thedistance between the plates. The ends of thecoil 5 are connected to terminals 16.