Abstract: A magnetic sweeper 20 is disclosed for capturing airborne particles which exhibit ferromagnetic behavior. The magnetic sweeper 20 uses a magnet(s) 43 having a magnetic field strength which captures particles coming within a predetermined distance of the magnet 43. A non-magnetic endless belt 31 is arranged about the magnet 43, wherein the particles are impinged against the belt 31 by the magnetic field lines of flux. This area is defined as a particle capturing first station. The belt 31 moves the captured particles further away from the magnet 43 to a second station. Located at the second station is a collector which includes a vacuum, a brush 41 and a particle flange. As will be appreciated by those skilled in the art, the magnetic field strength diminishes with distance from the magnet 43. Accordingly, after a certain distance from the magnet 43, the field strength drops to a point where the particles fall from the belt 31.

Abstract: A gas sensing instrument provides programmable control of the operating temperatures of an array of gas sensors for the detection of target gases in air. The control facilitates precise temperature setpoint resolution. The gas sensors in the array have an improved construction density with reduction in size and an extended operating life provided by reduced power consumption. A programmable circuit functions as a programmable-resistor temperature controller in a Wheatstone bridge configuration. A multiplying digital to analog converter circuit controls the ratio of voltage to current that functions as a resistance equivalent. The programmable circuit is interfaced with a computer to provide selectable temperature control for at least 256 setpoints.