Abstract: In a digital PCM-TDM telephone exchange, supervisory tones needed are centrally generated by a digital synthesizer. This includes a PROM (1) in which PCM codes for the tones needed are stored in successive memory locations. The tones used are the DR tone, which is a mixture of 350 Hz and 440 Hz, and the BN tone, which is 400 Hz. These are read out under clock pulse control (5-6-7) such that the DR tone bytes are read out at time slot 0 and the BN tone bytes are read out at time slot 1. They are then sent over a common intelligence bus (4) to all line and trunk interfaces.At each such interface the tone bytes are converted to analogue form so as to be continuously available. The tone (or tones) to be used is (or are) selected in response to instructions from the central control each of which specifies a program in the interface's processor. Such a program controls both the selection of the tone (or tones) needed, and the cadence (continuous, or interrupted in a defined manner).

Abstract: A dielectric composition, particularly suitable for the manufacture of ceramic capacitors, comprising lead magnesium niobate and lead zinc niobate. These may be additives, such as one or more oxide additives chosen from the group comprising silica, manganese dioxide, zinc oxide, nickel oxide, alumina, ceric oxide, lanthanum oxide and tungsten oxide, gallium oxide, titanium dioxide and lead oxide, or additives such as bismuth stannate. The compositions can be fired at temperatures between 980.degree. and 1075.degree. C. so that in the case of multilayer ceramic capacitors high silver content internal electrodes can be used. Higher dielectric constants, for example 9000 to 16,300, of the fired ceramics than conventional ceramics are obtained, thus permitting capacitor device size reduction.

Abstract: The primary coating (2) of an optical fibre element is reinstated over a fused joint between two silica fibre elements (3) by a casting process. The jointed silica fibre elements are arranged in a groove (8) of a mould (9, 10, 11) and liquid uncured primary coating material placed into the groove, the groove ends being blocked by the existing primary coatings (2) on the fibre elements (3). The coating material in the groove is cured by, for example, heating the mould. Secondary coating material (1) may be injection moulded using a two-part mould to reinstate the secondary coating over the cast primary coating.

Abstract: A dielectric composition, particular suitable for the manufacture of ceramic capacitors, comprising non-stoichiometric lead magnesium niobate, non-stoichiometric lead iron niobate and one or more oxide additives, which may be chosen from the group comprising silica, managanese dioxide, ceric oxide, lanthanum oxide, zinc oxide, alumina, tungsten oxide, nickel oxide, cobalt oxide and cuprous oxide. The compositions can be fired at temperatures between 980.degree. and 1075.degree. C., so that in the case of multilayer ceramic capacitors high silver content internal electrodes can be used and, in cases where three or more of the oxide additives are employed, higher dielectric constants, for example 10600 to 16800, of the fired ceramics than conventional ceramics can be achieved, thus permitting capacitor device size reduction. Additions of lead titanate may also be made to the dielectric compositions.

Abstract: A dielectric composition, for use in the manufacture of ceramic capacitors, and comprised of barium titanate (BaTiO.sub.3) with small additions of niobium pentoxide (Nb.sub.2 O.sub.5) and gadolinium sesquioxide (Gd.sub.2 O.sub.3).

Abstract: An animal feed additive comprises a composite of a relatively insoluble binder, a particulate soluble material and an active material. The particulate material is such that it is readily soluble under a particular range of pH conditions, e.g. under said conditions. Dissolution of the particulate material renders the binder water permeable thus permitting release of the active material.