GB418678A - Improvements in electromagnetic pickups - Google Patents

Abstract

418,678. Gramophone pick-ups. BRAUN, W. M., 17, Cretzschmarstrasse, Frankfort-on- Main, Germany. April 27, 1933, No. 12286. [Class 40 (iv).] A gramophone pick-up comprises a permanent magnet 11 secured to base 10 by a strap 12 and having U-shaped polepieces 15 between the lower arms of which an armature 21 is pivoted, the armature extending upwards through a coil 19 into the gap between the upper arms of the polepieces. According to the invention, the free end of the armature in the upper air gap is surrounded by a rubber &c. sleeve 26 normally contacting only with the armature to prevent the latter contacting with the polepieces. The coil bobbin may be held in position by grub screws 20 threaded into the polepieces and may house a rubber tube 25 surrounding the armature portion proper and having its upper part partly cut away by oblique cuts to form a wedge. The armature consists of a tube of cruciform shape, its upper extremity being flattened, but of increased width. The polepieces are preferably laminated and the length of the outermost laminations is successively decreased (Fig. 3, not shown) in order to provide maximum flux density in the air gap. The ends of the coil 19 are connected by leads 27 to lugs 28 secured to the base 10 by studs 29.