GB688634A - - Google Patents

Abstract

688,634. Galvanometers. GALL, D. C. Feb. 23, 1951 [Feb. 23, 1950], No. 4710/50. Class 37. The moving system of a galvanometer is suspended in a liquid silicone compound of the same density as the mean density of the moving system. As shown in Fig. 1, a moving coil has glass tubes 5, 6 extending from it with cork or similar discs 16, 17 mounted thereon; torsional suspensions 4 extend to terminals 19, 20 on a case 11 which is filled with a liquid silicone compound ; an expansion chamber 25 connects with the case through a narrow passage 26; the magnet system 13, 14, 15 extends through the case. Instead of an expansion chamber, the liquid may only partly fill the case, Fig. 3 (not shown), or the case may have a flexible base, Fig. 10 (not shown). The cork discs may be replaced by sleeves, Fig. 4 (not shown), or may be fixed to the moving coil, Fig. 5 (not shown). The moving coil may be wound on a cork form, Fig. 6 (not shown). The glass or plastic tubes 5 may be formed with bulbs to reduce the density of the moving system. The moving coil may be replaced by a moving iron or magnet armature, Figs. 8 and 9 (not shown). The internal wall of the case may be ribbed to increase the friction between the liquid and the case. Specifications 537,784 and 585,419 are referred to.