GB263948A - Improvements in variable electric condensers - Google Patents

Abstract

263,948. Spink, J. R., and Langley, J. B. Oct. 8, 1925. Condensers of the kind comprising a pair of telescoping metal cylinders separated by a sheet of dielectric and enclosed in an insulating casing, the inner member being in the form of a piston adapted to be displaced axially by a screw to vary the capacity, have the adjustable electrode and a supporting sleeve for the screw spindle split so as to form jaws whereby the spindle is resiliently gripped so as to steady the movement and form a good electrical contact. Two cylindrical electrodes 1, 2 are enclosed in an insulating casing 3 and separated by dielectric 12, the electrode 1 screwing into the casing and carrying an insulating disc 13 and terminal 14. The moving electrode 2 is adapted to be screwed along a steep-pitched, and preferably multi-threaded, spindle 5 rotatable in a sleeve 4, collars 7, 8 preventing axial movement of the spindle which is kept steady by a spring 9. The electrode 2 and preferably also the sleeve 4 are split at 16, 17 to form jaws adapted to grip the spindle resiliency and avoid back lash. A circular dial 20 is pivoted on a resilient bracket 19 whereby its milled edge is urged to engage a collet 21 of ebonite or the like on the spindle, whereby the dial is rotated with the spindle. An alternative indicator is in the form of a pin 10 on the electrode 2 extending through a slit in the casing 3 and serving also to prevent rotary movement of the electrode, although for this latter purpose the pin could be fixed in the casing and engage a groove 11 in the electrode. Fig. 5 shows a dual or balancing condenser comprising two oppositely movable electrodes 2 co-operating with fixed electrodes one of which is as in the previous form, whereas the other, 1<a>, screws on an insulating member 26 and carries a terminal 14<a>. In another form, two condensers, substantially as shown in Fig. 1, are placed one on each side of a forked supporting bracket, with an operating wheel located on the common spindle and between the prongs of the fork. For large capacity condensers a plurality of concentric cylinders may be used, with, according to the Provisional Specification means for adjusting individual ones relatively to one another for fine tuning.