Abstract: An integrated-circuit power-on reset arrangement which starts in a known state due to transistor sizing and to a current mirror circuit at least initially holding a bistable circuit in a predetermined one of its states.

Abstract: An electric lamp designed to operate in air and of the type incorporating at least one current-supply foil embedded within and extending along a light transmitting stem and welded at its inner and outer ends to an inner conductor and a terminal conductor respectively, in which the end face of the stem is unenclosed and is such that a proportion of radiation which is incident upon it from the lamp in use thereof is directed away from the foil and adjacent region of the terminal conductor. The invention is especially applicable to high power lamps and has the effect of reducing the temperature of the outer ends of the current-supply foils, which are vulnerable to oxidation.

Abstract: In a lamp having at least one seal of solid light-transmitting material, in which is embedded at least one current-supply foil, visible, I.R. and U.V. radiations which would otherwise be internally reflected from the seal surface are dispersed by providing on the seal either a non-uniform surface region or a light-dispersive coating, thus reducing the temperature of the outer ends of the foil and thereby reducing the risk of failure caused by oxidation. The seal may be formed with ribs or sand blasted or it may be provided with a coating of glass containing reflective particles or gas bubbles.

Abstract: An exposure meter includes a display device 16 on which is displayed a histogram 17. The x axis is divided into cells representing ranges of possible luminance values. The height (i.e., y value) of each cell of the histogram represents the number of individual areas within the scene to be photographed whose luminance falls within that cell. Alongside the histogram, a bar 18 is displayed representing the range of luminance values which can be photographed, this being calculated according to the film characteristics, shutter speed and aperture size. The information displayed at 16 is provided by a processor which receives information from a keyboard 12 and a color camera photosensor onto which is focused an image of the scene to be photographed.

Abstract: An electrical socket connector in which individual contact members are located and retained on pegs projecting from a body member of electrically insulating material, the contact members being arranged for insulation displacement electrical connection at one end to insulated wires of two different thicknesses, and having means to set the gap between contact-making cantilever springs for co-operation with an associated plug connector. Outer covers may be latched to the body member, and the body member or one of said covers may allow access to said contact members for test probes.

Abstract: A semiconductor diode laser of the kind in which laser radiation occurs in an active region in a layer (3) of semiconductor material wherein optical confinement of the radiation to a portion (19) of said layer so as to direct light from said region to a light waveguide is obtained by virtue of differences in the refractive index of different parts of said layer arising from mechanical stresses in said layer, produced, for example, by differential thermal contraction during fabrication of the laser of different parts (96, 11b and 13, 15 or 21 and 5 or 23 and 3) of the laser structure.

Abstract: An antenna is pivoted on a mounting about a first axis (3) and is driven by a screw threaded drive member (5) to which it is pivoted about a second axis (4). The drive member (5) engages a drive mechanism (6) which is pivoted about a third axis (7) all the axes being parallel. At one position of adjustment (illustrated) the second and third axes (4,7) are in line with each other enabling the drive member (5) to be pivoted to the position shown in broken lines thereby doubling the size of the arc through which the antenna can be rotated.

Abstract: A switch for switching a single fibre to any one of a plurality of fibres by aligning their end faces is composed of a funnel-shaped guide. The single fibre is mounted in the narrow end portion of the guide and the plurality of fibres are held in the wide end of the guide. Each of the plurality of fibres is independently movable longitudinally into the guide, for example using electromagnetic actuators, so that as a desired fibre moves further into the guide, its end is guided towards the narrow end where it will align with the end of the single fibre.

Abstract: A CCD frame transfer image sensor wherein the effective integration period can be shortened by electrical means. The sensor comprises an image section having a first photo-sensitive portion of an array of CCD channels and a store section having a second light shielded portion of the array. Means are provided for controlling the potentials applied to the control electrodes of the array so as to transfer along the channels charge generated in the image section into a charge sink structure during one of the active line periods at a frequency outside the bandwidth of the output signal of the sensor.

Abstract: A semiconductor device incorporating two superlattices in the GaAs/AlGaAs system separated by a relatively thick layer of GaAlAs is described. The device displays negative differential conductance.

Abstract: In a telephone system in which digitally coded speech or data is transmitted in burst mode between a subscriber's set and the local exchange the bursts may be of the same length in either direction or longer in one direction than the other in dependence upon the information to be transmitted. Binary digit values making up the bursts are assembled for transmission in and held following reception of a shift register, and different output points along the register are selected in dependence upon the length of burst to be transmitted.

Abstract: To ensure security of interrupt input signals to a computer system (30-3N) with minimum interruption of the running of programs in the system, two interrupt logic units (1) receive interrupt signals on leads (20-2x) from connected apparatus and store flags representing the interrupt signals in an interrupt store (2). Control logic (3) compares each input signal with presettable criteria to determine if such signal is an interrupt signal and, if so, causes the data to be transferred by way of a read register (5) to the connected computer system (30-3N). At the same time the control logic (3) of one of the units (1) designated as the active unit also causes an ouput on a lead (11) to the other unit (1) designated as the standby unit.

Abstract: A display device which is corrected for vibration, for example between screen (4) and the electron gun (2) in a C.R.T. (1). The device comprises an optical system (6) on the observer side of the screen (4) for directing the light from a small part of the screen (9), onto which the electron beam is directed at intervals, onto a photocell (10) which detects the position of the light spot. The output signal from the photocell is processed in a circuit (5) to provide a correction signal which is applied to the deflection system (3) of the C.R.T. to reduce the deviation of the light spot from the position it would have in a vibration-free environment.

Abstract: A switched mode power supply has a sense transformer (TX2) with three windings. A first (primary) winding (WD) is in series with the primary winding (WP1) of the power transformer (TX1). Current regulation of the output is provided via a second (sense) winding (WS). Voltage regulation of the output is provided by a further (third) winding (WC) being connected in parallel with the secondary winding (WP2) of the power transformer for producing isolated feedback of an output voltage error signal using the sense transformer (TX2) as a current summing transformer.

Abstract: A switched mode power supply in which the power switch (TR1) is modulated by a resistance-capacitance oscillator (COM, R1-R5, CT). During each on-period of the switch (TR1) a secondary winding (WS) of a sense transformer (TX2) develops a unipolar sense voltage which is applied to a capacitor (CT) in the oscillator while it is charging, so as to vary the charging time and hence the on-period, the off-period of the switch (TR1) being constant.

Abstract: To effect transfer of messages between data units (1-4, 5-8) a switching network of binary distributors (21-24, 31-38) and concentrators (41-48, 51-54) is used. For each distributor in the network the message is preceded by a respective single data bit which is absorbed in the switching system. Thus at the message destination all addressing bits have been absorbed, only the required message being received. Concentrators have both input paths enabled to their respective output paths except when a message is passing through the concentrator when the non-transmitting path is disabled.Any message arriving at a blocked concentrator is lost. Accordingly an acknowledging system uses a reverse path set up in parallel with the forward path to acknowledge receipt of the message. Alternatively the reverse path may be used to return a message fail indication from a blocked concentrator.

Abstract: A telecommunications exchange includes line identification apparatus in which signals on additional wires (the `p` wires) (1) which are switched in parallel with the speech pairs are used to identify an originating exchange line circuit. On detection of seizure of the `p` wire (1) at one of a number of call logging points (11) a data signal is transmitted by a transmitter circuit (9). On detection of such a signal a receive circuit (2) adds a plurality of data bits to the signal identifying one of a number of associated `p` wires (1) on which the signal was received and transmits the modified data signal to a receiver multiplexer (4, 4'). On receipt of the modified data signal the receiver multiplexer (4, 4') adds a respective plurality of data bits to the signal identifying one of a plurality of receivers (2) connected thereto and retransmits the signal to a further multiplexer (5, 5').

Abstract: A loop-back unit for connection at the subscriber's end of a line (15) to provide a loop-back line testing facility, the unit comprising a transformer (1) with a first winding (3) and second winding (5) of relatively high inductance, connected in series across the line, and a third winding (7). In normal operation the subscriber's unit (17) is connected across the second winding and the transformer is transparent to signals on the line. To test the line a tone is applied to the line which is detected by a detector (25) connected across the third winding and in response to the detector output a control circuit (23) operates a switching arrangement (21) to disconnect the subscriber's equipment temporarily from the second winding and apply a test tone across the second winding. The unit is capable of satisfactory operation despite faults in the subscriber's equipment.

Abstract: A data storage device comprising a planar integrated circuit (13) formed on a face of a body of an electronic storage material which provides a plurality of spaced discrete columns of spaced discrete electric charge storage sites (5), the columns extending in directions normal to the plane of the intergrated circuit and the integrated circuit providing access to the storage sites.

Abstract: A color cathode ray tube display device which is compensated for color distortion due to, e.g. vibration, comprises means (9-12) for producing signals representing the respective color light outputs from the phosphor screen (5), means (13) for comparing the signals with the corresponding color impact video signals and means (14) to provide a correction signal to reduce any deviation between the signals.