Abstract: A discharge lamp is provided with a starting aid in the form of a loop of conductive wire arranged around the discharge lamp arc tube and a novel spark gap. A conductive element is electrically connected between the loop and an insulating sleeve adapted to form a spark gap by means of the conductive element wrapped around an opening in the insulating sleeve. The opening can be in the form of a drilled hole or slot and the arrangement is particularly useful in the restricted confines of a sealed beam reflector lamp.

Abstract: Carbonating apparatus includes a reservoir to be filled with fresh water through an outlet. Rotation of a control opens a valve, so that water passes from the reservoir into a pressure vessel. The control is then depressed to cause pressurized gas to be introduced into the water in the vessel, via a nozzle, from a gas cylinder, so as to carbonate the water. A slidably-operable control is then moved by an initial amount to cause a venting valve to open, thereby venting excess gas in the vessel to atmosphere. Further sliding movement of the slidably-operable control depresses a lever connected to an outlet valve, which permits dispensing of the carbonated water from the vessel, via a spout.

Abstract: A heating unit suitable for mounting in a cooking hob includes a circular tray having a layer of thermally-insulative material disposed therein and a peripheral thermally-insulative wall, within which four infra-red lamps, each containing a tungsten filament, are supported. The tray also includes an inner thermally-insulative wall, which encloses the length of each filament. Between the peripheral and inner walls, two conventional, wire-wound heating elements are disposed. The filaments and the elements are energizable independently and/or concurrently, and series and/or parallel combinations of the filaments and the elements may be switched to provide various discrete power outputs.

Abstract: In a magnetron a spinner (22), rotatable on a longitudinal axis (x) has a number of evenly spaced markings formed circumferentially on an exterior surface. The markings are sensed, as the spinner rotates, by a photo sensitive transistor (PT) coupled to window (26) in the vacuum envelope of the magnetron by a fiber optic pipe (FP1). The periodicity of pulses, generated by the transistor in response to movement of markings past the window, is divided in a network (43) to generate a succession of further pulses. The further pulses are then counted in circuit (44) and the instantaneous count compared with reference frequency values stored in memory (46) to generate an output signal O/P(1) related to the instantaneous magnetron frequency.

Abstract: A thermal limiting device for controlling one or more sources of infra-red radiation, preferably tungsten-halogen lamps, mounted in heating apparatus, consists of a metallic wire arranged to de-energize the sources when it is subjected to a predetermined temperature. The wire is accommodated within a quartz tube, which selectively transmits and absorbs infra-red radiation of different wavelengths. An infra-red reflective coating is applied either to the wire or to the inner surface of the quartz tube to prevent infra-red radiation transmitted through the quartz tube from reaching the wire, while infra-red radiation of a particular wavelength, which is absorbed by the quartz tube, heats the wire by thermal conduction and convection, so that the limiter is primarily responsive to radiation only of that particular wavelength.

Abstract: In some industrial situations a battery charger is used to supply d.c. power to an electrical equipment, and a battery is connected across the output terminals of the charger so that a "back-up" supply is available if the charger should fail. An indicating circuit is used to generate a warning if an open circuit condition arises in the battery charging circuit. The indicating circuit operates by monitoring the output impedance of the battery charger. If the output impedance exceeds a threshold value the indicating circuit generates a warning signal.

Abstract: A linear filament assembly for a halogen cycle or other incandescent lamp comprises a generally linear filament usually a coil or coiled coil, supported at opposite ends by substantially rigid conductive leads. A rigid insulating rod, preferably of quartz extends generally parallel to the filament, and a plurality of supports extend between the rod and the filament, each support being fixedly secured to the rod and supporting the filament. The supports are embedded in the rod, this being achieved by heating the rod at the point of insertion until it is sufficiently soft to insert the wire without excessively distorting the rod.

Abstract: The invention provides an improved method of construction of a prefocus lamp, to improve positioning of the filament relative to the lamp cap, and a lamp so made. The lamp envelope has a pinch seal with V-shaped grooves into which a resilient ring is sprung. This assembly is a sliding fit in the lamp cap and is slid therein to have substantially only line contact between the ring and the cap. The envelope can then be relatively easily rocked and otherwise moved in the lamp cap to be precisely positioned. When the positioning is complete solder previously placed in the cap is melted, the position being such that it flows over the ring and fixes the ring to the lamp cap.

Abstract: A multimeter is provided with two slide switches, one switch providing a selection of four functions, i.e. "OFF", "AC", "DC/JUNCTION" and "RESISTANCE/CONTINUITY" and the other switch providing a selection of six range settings and a "JUNCTION/CONTINUITY" setting. The multimeter also has three input sockets for insertion of test leads. At least two of the combinations of the switches and sockets are incompatible, i.e. "AC" and "JUNCTION/CONTINUITY", and a current input socket and "RESISTANCE/CONTINUITY". An internal buzzer is incorporated in the multimeter to provide an audible indication to a user that an incompatible combination has been selected. The buzzer is preferably also used in junction and continuity test modes.

Abstract: A sifting device consists of a mesh with a vertical wall and protrusions, which attach the device to the rim of a bowl of a food processor. An open-based cone is co-axial with a central rotatable hub and is provided with protuberances on the inner surface thereof. In operation, ingredients are placed in the device and protuberances engaged in turn with a projection, as the hub is rotated, so as to provide undulations of the mesh, thus tossing the ingredients in the device and introducing them into the bowl through the mesh.

Abstract: An infra-red lamp consists of a quartz tubular envelope sealed at each end with a respective pinch seal. A tungsten filament supported within the envelope is electrically connected, via a molybdenum foil strip and lead wires within the pinch seal to a connector for connection to a power supply. Each pinch seal is substantially wholly enclosed within a ceramic housing, which is preferably provided with a locating flange, to protect the pinch seal in part from heat emitted by the filament and to assist in location of the lamp in an operating environment.

Abstract: Solid fuel combustion equipment in the form of a grate assembly comprises longitudinally extending support elements on which are mounted laterally orientated grate bars. The support elements are pivotable about their horizontal axes and are provided with sealing means at their adjacent margins to effect a seal to prevent in use passage of air when the elements are horizontally aligned. De-ashing of the grate assembly in use is achieved by tipping the support elements, whereupon ash falls to a receiving area when it is removed.

Abstract: An arc discharge lamp is provided using sealing compositions comprising mainly Al.sub.2 O.sub.3 --SiO.sub.2 --MgO. Preferred compositions include between 25 to 28% by weight of MgO and 13 to 21% by weight of Al.sub.2 O.sub.3 since these have lower melting points than others in the group. Additives of B.sub.2 O.sub.3, nucleating agents and HfO.sub.2 and other rare earth oxides are preferred. The sealing compositions are used to seal end closure members of alumina or CERMET to ceramic arc tubes for use in discharge lamps. The compositions are selected to have linear expansion co-efficients compatible with the materials of the end closures and arc tubes. The methods described give scaling times of between 3 and 4 minutes.

Abstract: An instrument for measuring electrical resistance or reactance comprises a sine wave generator which generates an a.c. signal and reference signals for a phase sensitive detector. The a.c. signal is applied to a decade attenuator which adjusts its amplitude in dependence on a range switching. The signal is passed to a bridge section, wherein it is applied to a component to measure the value thereof. A voltage output, indicative of the value, is fed to a gain block, wherein its amplitude is re-adjusted in dependence on an input from the range switching. The voltage output is operated on by a phase sensitive detector and passes to a digital display. In the reactance mode, set by a function switching, the a.c. signal is phase shifted before being applied to the component, so that the voltage output is in phase with the reference signals.

Abstract: An electrically conducting cermet for use in a closure assembly in a high pressure sodium discharge lamp which cermet comprises a sintered compact of refractory oxide granules and a conducting network extending throughout the cermet wherein said network is provided by a layer of niobium and, optionally, at least one other specified metal. The cermet is, because of the niobium content of the metallic network, permeable to hydrogen and lamps incorporating this cermet can therefore be stabilized in acceptable times.

Abstract: Heating apparatus includes a tray having a layer of insulative material disposed therewithin, above which a number of infra-red lamps are supported. The ends of each lamp are provided with a pinch seal having an amp tag connector, which is connected to the respective end of a filament within the lamp, sealed therein. Each pinch seal is enclosed within a ceramic housing and the heating apparatus is mounted beneath a layer of glass ceramic. A heat-conductive stud is intimately disposed between the layer and the pinch seal, via an aperture in the housing, so as to provide a good heat-conductive path from the pinch seal to the relatively cool glass ceramic.