Abstract: In a high pressure electric discharge lamp employing at least one ribbon seal incorporating a strip (3) of refractory metal foil extending through the wall of an envelope (1) of fused silica, and connected at its outer end to at least one external lead rod (5) and at its inner end to a rod (4) which constitutes or provides a support for an electrode of the lamp, with the foil and adjacent ends of the lead rod or rods and the electrode embedded in the envelope wall, wherein a said lead rod and/or an electrode rod is surrounded, over at least a part of the region of the rod which is embedded in the envelope wall, by a closely wound coil (6) of a relatively thin refractory metal wire. This enables the fused silica of the envelope to be pressed tightly around the rod in that region in manufacture while reducing the tendency to crack on cooling.

Abstract: In a temperature sensor of the kind comprising a bipolar transistor (1) having an adjustable constant current source (3) connected between its collector and base regions (7 and 9) and its emitter region (11) connected to the output of a high gain amplifier (5) whose input is derived from the current source (3), the junction between the emitter and base regions (11 and 9) of the transistor is a heterojunction and each of the emitter and base regions (11 and 9) is provided with a metal contact (17 or 19) separated from the associated region by a barrier layer (21 or 23) of an amorphous tantalum iridium alloy. The use of a heterojunction for the transistor emitter-base junction increases the temperature range of the sensor while the barrier layers ensure metallic stability at the high temperature end of the sensor temperature range.

Abstract: As assembly in which individual units of electrical or electronic apparatus are attached to one side of a perforated vertical wall and a cooling channel is formed on the other side of the wall. Two parallel vertical walls each having apparatus attached to their outer sides may form a cooling passage or chimney between them. The flow of air into the passage may be directed by one or more inclined deflector plates, and the flow of air to the apparatus or within the passage may be enhanced by fans.

Abstract: In a cathodoluminescent lamp of the type having an electrically conductive coating forms the anode on the interior surface of the bulb wall, a phosphor coating overlies the anode coating and an electron emissive cathode below a grid, the lead to the anode passes through a glass tube, additional to the exhaust tube, incorporated in the pinched foot tube, and is sealed through the pinch, and the contact between the anode lead and the anode coating on the bulb is provided by a bent metal strip attached to envelope the neck and partially covered by the anode coating, which extends partly down the neck, the end of the anode lead being engaged with an upstanding portion of the contact strip.

Abstract: A method and apparatus for locating the position of a fault occurring in an electric power transmission system wherein an indication of the position of the fault with respect to a monitoring point is obtained from the time taken for a transient component of fault signal to travel from the monitoring point to the fault and back to the monitoring point after reflection at the fault.

Abstract: The position of a fault occurring in an electric power transmission line (1) is determined by "labelling" a voltage or current pulse originating from the fault and reflected by the end of the line, or some other point in the system, moving back towards the fault, and then measuring the time taken for the labelled pulse to return to the measuring point near the end of line. The "labelling" is achieved by predicting from known data and the time of arrival of the reflected pulse the amplitude of the voltage pulse and comparing the prediction with the measured value. Apparatus for carrying out the method is described.

Abstract: A data processing system having a large number of data processors (1-4) grouped in `clusters` is used in the control of a telecommunications exchange. The arrangement is such that any one of the processors may pass data to any other of the processors, in its own cluster by way of a synchronous data bus (5), or on other clusters by way of an interface (18, 19) and an asynchronous data bus (22). The arrangement permits larger number of processors (1-4) to have access to storage without undue delay in access to stored data.

Abstract: A force sensor comprising a field effect transistor (FET) structure formed on a substrate, having an insulating layer overlying the substrate adjacent to the channel region of the transistor structure. A layer of piezoelectric material overlies the insulating layer, the layer of piezoelectric material having a portion which extends beyond the insulating layer to form a cantilever structure overhanging a portion of the channel region. A control electrode overlies the cantilever structure. Forces acting on the cantilever structure modify the charge distribution in the underlaying channel region, thereby to cause the drain current of the transistor to vary with any variation of force on the cantilever structure.

Abstract: A motor control system in which an actual torque indication is derived from the motor and compared with a reference, or demand, torque. From the difference signal is derived a stator M.M.F. in magnitude and position relative to a reference frame locked to the rotor. Orthogonal components of this stator M.M.F. are derived and transformed to stator phase winding drive signals.

Abstract: In a radio receiver a multipath fade compensating circuit comprises a single-pole filter circuit the center frequency and Q of which are controlled in dependence upon the amplitudes of signal components in narrow frequency bands within the band of frequencies passed by the filter circuit. The narrow bands may be selected from an array by a microprocessor, or may be derived using variable frequency filters.