Abstract: A blower includes a housing including an inlet and an outlet, a bearing-housing structure provided to the housing and adapted to rotatably support a rotor, a motor provided to the bearing-housing structure and adapted to drive the rotor, and an impeller provided to the rotor. The bearing-housing structure includes a bearing shaft having a bearing surface that rotatably supports the rotor. The bearing shaft provides only a single bearing of the non-ball bearing type for the rotor.

Abstract: A wideband meander-line circular polariser includes a substrate and a plurality of parallel meander shaped conductors (meander lines). Each parallel meander line (20,30) is loaded with electrically isolated capacitive elements (40) enclosed within some or all of the individual meander loops, allowing the polariser to be made electrically smaller for a given wavelength whilst maintaining the desired resonant frequency. Multiple layers of the device ma be used.

Abstract: A semiconductor switch die (30) is mounted on one face of a substrate (31) and has a temperature sensor (10) on the opposite face to monitor the temperature in the vicinity of the semiconductor die. A current sensor (4) and voltage sensor (5) supply signals to a processor (15) to calculate power dissipated by the semiconductor device. The processor calculates the temperature of the device itself from the measured temperature and the dissipated power. If this exceeds a preset limit, the switching device is opened to prevent damage.

Abstract: An electrical system has a solid state switch controlled by a circuit emulating the thermal sensor of an electrothermal circuit breaker. A current sensor senses current flowing through the switch. In one arrangement, the current sensor supplies an output to a multiplier, which derives a voltage representative of a current squared, this being supplied to a resistor capacitor circuit having a time constant emulating the thermal sensor. In another arrangement, the output of the current sensor is supplied via an A/D converter to a processor that calculates the difference between heat gain and heat loss of the emulated thermal sensor. The switch is opened when the emulated temperature exceeds a threshold.