Abstract: An electronic assembly has a substrate with several conductive tracks and with a switching matrix within the thickness of the substrate. Several groups of identical integrated circuits are mounted on the substrate, one circuit from each group being operatively connected into the assembly by the switching matrix. A processor detects malfunction of a circuit and controls the switching matrix to disconnect that circuit and operatively connect into the assembly an alternative circuit from the same group.

Abstract: An integrated circuit substrate is made by exposing a mask to a composite representation of the pattern of integration of several different dice. The mask is exposed several times to produce several composite representations on the mask. Several different composite representations may be formed on the same mask. Identical aligned composite representations are checked by optically comparing corresponding dice in different composite representations via respective optical systems. The several composite representations on the mask are transferred simultaneously to the substrate to reproduce the pattern of integration of the dice at a plurality of locations in the substrate.

Abstract: A control system for a gas-turbine engine has two parallel control units, either one of which can be switched to supply control signals to the engine in response to input signals, such as from the pilot's control lever and from various sensors. Each unit has a limiter that limits the fuel supply to the engine if the engine speed approaches or exceeds a predetermined maximum. A monitor unit in each control unit detects when the limiter has assumed control of the engine for more than a predetermined time, and switches the system to control by the other control unit. The predetermined engine speed may be different for different settings of the pilot's control lever.

Abstract: A hydraulic control system has two fluid supply circuits which control fluid pressure supplied to respective chambers of a fluid-controlled actuator, each chamber having an individual piston mounted on a common actuator rod. In normal operation, a major part of the pressure is supplied to the actuator by the first circuit in accordance with control signals derived from an external source. The second circuit supplies pressure to its respective chamber at a lower level in accordance with control signals derived from the differential pressure across the piston in that chamber, the pressure supplied by the second circuit acting to reduce the differential pressure across the piston. The system also includes a control unit that responds to malfunction of the first circuit or error in the control signals supplied to the first circuit, by disconnecting the first control circuit from control of the actuator, such as by equalizing pressure across the piston in the first chamber.

Abstract: An electrical indicator has a consecutive series of light-emitting diodes which are arranged along a straight or curved reference scale. A limited region of the series, comprising several diodes, is energized and this illuminated region is displaced along the scale upon change in an electrical input variable supplied to the indicator such that the position of the region provides an analogue indication of the value of the input variable. To improve the appearance of the display and reduce power consumption, the brightness of the region varies along its length with one or both of the outermost diodes being energized at lower levels than another of the diodes. The indicator may include a shift register having a number of storage locations, each for storing signals representative of a corresponding one of the light-emitting diodes, the signals at these locations being displaced in accordance with change in value of the input variable.