Abstract: A capacitor simulator circuit comprises a first node, a first capacitor coupled between a second node and a reference potential, a second capacitor coupled between a third node and a reference potential, a resistor coupled between the first and third nodes, a first electrical switch arranged when in an open state to electrically isolate from one another the first and second nodes and when in a closed state to electrically coupled together the first and second nodes, a second electrical switch arranged when in an open state to electrically isolate from one another the second and third nodes and when in a closed state to electrically couple together the second and third nodes.

Abstract: A fuel supply system for use in rotary wing aircraft is described. The system comprises a separating means 10 for: receiving an air, vapor and fuel mixture at relatively low pressure from a fuel tank; separating the air and the vapor from the mixture; and providing a fuel supply at a relatively high pressure, and a pump means 12 for returning the separated air and vapor to the tank.

Abstract: A power control circuit in which a direct current voltage (Vp) proportional to the a.c. power applied to a load (L) is derived from voltages (Vc and Vv) proportional to the a.c. current flowing in the load (L) and the a.c. voltage across the load, respectively, and compared with a voltage (Vnp) representing nominal power to the load to provide a d.c. signal (Vd) the amplitude of which is utilized in conjunction with a staircase or ramp generator (SG) to add or deduct cycles of the a.c. power to or from the load circuit according to a predetermined load power rating and in dependence upon variations in the a.c. supply voltage to the load and changes in resistance of the load.

Abstract: An electronic compass for vehicles comprising at least two magnetic sensors arranged in use to be respectively responsive to orthogonal horizontal components of a magnetic field which includes the earth's magnetic field and a spurious magnetic field which is associated with the vehicle, for producing electrical signals corresponding to said components, data storage means arranged to store signals derived from the sensors as the vehicle is rotated in the horizontal plane during a compass setting cycle, and signal processor means responsive to electrical signals produced by the sensors after the setting cycle has been completed and to the signals stored during the setting cycle, for providing output signals indicative of the bearing appertaining to the heading of the vehicle in which the effects of the spurious magnetic field are compensated for.

Abstract: An electronic compass for vehicles comprising three magnetic sensors arranged in use to be respectively responsive to orthogonal components of a magnetic field which includes the earth's magnetic field and a spurious magnetic field which is associated with the vehicle, for producing electrical signals corresponding to said components, tilt sensor means responsive to vehicle tilt with respect to the horizontal plane, data processor and storage means arranged to store signals derived from the sensors as the vehicle is turned through a compass setting cycle, and signal processor means responsive to electrical signals produced by the sensors after the setting cycle has been completed and to the signals stored during the setting cycle, for providing compensated signals related to the bearing appertaining to the heading of the vehicle in which the effects of the spurious magnetic field are compensated for and further processor means to which the compensated signals are applied and which is responsive to the tilt se