Abstract: An acoustic transducer of novel structure suitable for automatic assembly is made by arranging with its wall upwards a generally cup-shaped rear cover having a cylindrical wall out-turned at its upper end and extending from the rim of a base divided along a chord into a major segment for receiving an electromagnetic driving unit and a terminal receiving minor segment at a higher vertical level than the major segment. The major segment has on its inner face fixing lands disposed symmetrically with respect to a diameter normal to said chord offset away from the minor segment and extending inwards from the side wall. Each fixing land is formed to define a fixing location and having on its face presented to the minor segment an upstanding locator wall.

Abstract: Electromechanical apparatus for setting up and erasing alpha-numeric characters or other symbols in braille by means of a tactile display. Dot pins simulating braille are supported for movement within holes in a display plate to a position protruding therefrom to form tactile characters and for retraction to a withdrawn position flush with the surface of the display plate. Solenoid-operated plungers are arranged to selectively project the dot pins. Latch elements are movable by energization of the solenoid to a position to support the plungers in their operative position, a common support for the latch elements movable in a plane perpendicular to the axis of the support plungers to remove the latch elements and spring means for restoring the support plate to its initial position.