Abstract: A spotlight comprises a light source (14) mounted within a enclosure (11) fitted with a light-transmissive cover (28) which is formed with a central opening (29) above the light source. A clearance space between the light source and the cover allows light from light source (14) to spill over into the enclosure and thereby illuminate the cover from behind. Another enclosure (12) containing control gear (17) for the light source is thermally insulated from enclosure (11) by an air gap (21).

Abstract: A hydrogen getter for use within the arc tube assembly of a gas discharge lamp e.g. a high pressure sodium discharge lamp, comprises a layer (11) of a getter material (eg Ti) sandwiched by diffusion bonding between layers (12, 13) of a hydrogen permeable material (eg Nb) there being an exposed region of getter material. Hydrogen getters in the form of disc-like washers are formed from the sandwiched layers by a stamping process.

Abstract: A system for personalization of I.C. microchip cards includes a feed mechanism, which feeds blank plastics cards into an encoder, which encodes a magnetic stripe on each card with personalized data from a magnetic tape or disk. Correctly encoded cards are then fed to a personalization module consisting of up to sixty I.C. write stations for programming a microchip of each card with data corresponding to that encoded on the magnetic stripe. The module moves relative to the in-feed and out-feed lines of the cards, at a speed in dependence on the programming time, which can vary depending on the volume and complexity of the program. The magnetically encoded and programmed cards may then optionally be provided with human-readable information by an embosser or printer before being fed out of the system.

Abstract: A substrate for supporting electrical components, such as thick film resistive heating elements, comprises a plate member, such as a metallic plate member, coated on one or both of its flat surfaces with a glass ceramic material.It has been found that the problems of (a) electrical breakdown between the metallic plate member and the thick film resistive heating element and (b) lack of adhesion between the thick film and the glass ceramic material can be substantially reduced or eliminated by reducing the porosity of the glass ceramic material. Methods of producing a glass ceramic layer having a low porosity, involving a two-stage heating process, are described.

Abstract: A system for the remote reading of a gas meter includes an interface unit within a domestic residence but situated such that an input/output terminal for the interface unit is accessable from the exterior of the residence, and a hand-held meter reading unit for connection to the terminal in order to read and record the value of the gas consumption indicated by the meter. The meter reading unit has two LED sources, whose outputs are combined a Y-coupler, for passage into the interface unit when an optical fibre is connected thereto. At a multiplexer, the combined beam is dispersed according to wavelength and separately passes along a fibre array to respective roller digits of the tumbler for reflection or not according to the displayed reading. Reflected light passes back through the system, is divided at a Y-coupler and passes to a de-multiplexer such that the light returning in respect of the roller digits can be measured and displayed at a light detector and liquid crystal display.

Abstract: A helically scanned optical tape recording and replay system has a rotating drum with a galvanometer mirror for controlling the tracking of a number of write and read light beams during recording and replay. Dynamic focussing of the beams on the recording medium is controlled by means of a voice-coil actuator operating on a lens situated outside the drum. An optical rotator is provided through which the write and read beams pass following beam combinations, the optical rotator being driven by a motor to rotate at half the rotational velocity of the drum, and thereby present an image to the optical tape which rotates synchronously with the drum.

Abstract: A magnetic sensor arrangement for monitoring movement of a vehicle on a path includes a three-axis accelerometer (1) and a processing circuit (2) for evaluating the vector product Hp of magnetic field vectors measured by the accelerometer when the vehicle is at two successive positions on the path. The vector product is utilized to evaluate a parameter related to vehicle trajectory. The arrangement may be used to generate a firing signal in an explosive mine or for monitoring a flow of vehicles along the path.

Abstract: A transmitter station has a data source, a crypto unit, a buffer store for encrypted signals and a transmitter with an aerial, all with a common power supply. A switching control unit has a position in which it connects data source and crypto unit to the power supply but isolates transmitter therefrom, and another switch position in which transmitter is connected to the power supply while data source and crypto unit are isolated therefrom. In this way, if any signals output from data source pass directly (i.e. not via crypto unit) to the input of transmitter, they will not be sent on into the network because transmitter is "off" (i.e., de-energized) at that time.

Abstract: An arc tube for a high pressure discharge lamp comprises a sealing element displaced from the end and sintered within the arc tube to form an overhung end. An electrically conductive cermet end member has a boss member which fits within a central aperture in the sealing element to thereby centralize the cermet end member within the arc tube. The cermet end member is therefore positioned within the arc tube independently of the arc tube wall and any distortion of the arc tube which has taken place during sintering of the sealing element has no effect. Preferred dimensions of the components are given so that cracking of the cermet end member is avoided and suitable electrical resistance is achieved.

Abstract: An arc tube (13) for a high pressure sodium discharge lamp (10) contains a quantity of a getter materal which comprises an alloy of titanium and niobium metal. The alloy is in the form of a coiled wire (31) which is wound on a tungsten electrode shank (29). The wire may have a sheath of niobium metal.

Abstract: A phosphor comprises a chromium activated alkaline earth aluminate having a hexagonal crystal structure and incorporates divalent europium as a sensitizer. The phosphor may also incorporate one or more of divalent manganese and/or zinc and/or magnesium. Such a phosphor emits in the infra-red.

Abstract: A digital phase-locked loop using a binary overflowing accumulator as a numerically controlled oscillator has external compensation to eliminate frequency-dependent phase offset problems while not requiring any second-order filtering.Operation of the NCO adder initiates with value set by the center frequency control and under the latching action of the latch clocked by the reference oscillator produces a linearly stepped output. Detection of the most-significant bit values produces a square wave at the output. The phase detector latch is used for phase correction, while comparator eliminates steady-state phase error.

Abstract: A demodulating circuit includes an exclusive OR gate which has a first input for a frequency modulated signal and a second input connected via a delay to a frequency dividing circuit. The second input is initially low so that an output signal is produced by the gate, enabling a pulse generator, whenever the first input is high. The pulse generator produces a train of pulses of predetermined length and frequency. These pulses are counted in a counter and the count is compared in a comparator with a predetermined number n. On the n.sup.th pulse, the comparator sets a bistable circuit which then produces an end-of-pulse-train signal, triggering the frequency dividing circuit. In response, the frequency dividing circuit produces an output signal which causes the second input of the OR gate to go high, thereby disabling the pulse generator.

Abstract: An oven includes two tungsten-halogen lamp units strategically positioned, so that infra-red radiation generated by the units is emitted into the oven cavity to brown or grill food placed in the cavity. The cavity also includes, in one embodiment, an infra-red-reflective support for reflecting infra-red radiation emitted from the lamp units onto the underside of the food. In another embodiment, the support includes a heat transfer medium for absorbing infra-red radiation from the lamp units to produce heat and convey the heat to the underside of the food for browning. The oven may include a source of microwave energy and the support may have a microwave absorbent coating, which produces heat for browning the underside of the food.

Abstract: In double ended high pressure discharge lamps such as are used in sealed beam reflectors the leads pass through the reflector bowl close to the axis thereof and close to each other giving risk of flashover therebetween, particularly with the high voltages required for hot restarting. To reduce such effects at least one of the leads has a length forming part of a circle terminating at one end and a sleeve of insulating refractory material conforming generally to the same circle is fitted to at least part of the circular part.

Abstract: A lighting device includes a light pipe and a tungsten halogen reflector lamp transmitting light beams parallel with the axis of the light pipe. This allows the use of a dichroic filter which provides for an increased transmission whereby low wattage lamps (36 w) can be used instead of the more usual 100 to 200 w light sources. A number of shaped prisms can be used as end arrangements whereby different effects are obtained, for example, bi-directional, omni-directional or angled beams can be provided.

Abstract: A chemical-sensitive semiconductor device in the form of a chemical-sensitive field effect transistor, suitable for testing relatively small volumes of a fluid analyte, comprises a substrate provided with a passageway, interconnecting its major surfaces, along which the analyte can pass. Drain and source regions are formed at opposite ends of the passageway and a chemical-sensitive gate region is formed on the sides of the passageway.

Abstract: A heater comprises a substrate having an electrically-insulative ceramic coating and a heater track deposited on the coating and electrically connected to a power supply via ends. The heater track consists of a composite material having predetermined proportions of a metal and a material capable of undergoing a reversible change in volume at a predetermined phase transition temperature. The change in volume changes the proportions of metal to material and thus changes the resistivity of the composite material, so that the heater can be used as a self-regulating thermal cut-out device by limiting its own heat output to the phase transition temperature.

Abstract: A switched mode power supply has two separate, alternately conductive switching paths, each including two switching elements. Smoothing capacitors are connected in series across the series connection of one switching element in each of the switching paths and to the supply lines via further capacitors. In a further embodiment, a primary winding of a transformer is connected in series with the load and a capacitive network incorporating a secondary winding of the transformer is provided in conjunction with one of the switching elements in each path. Current draw from a rectified supply input is controlled at least once in each cycle by current flowing in the secondary due to the current in the primary.