Gas sensor

An instrument comprising:

• a housing including a housing part having an inner surface;
• and
• a printed circuit board disposed within the housing;
• wherein the housing part of the instrument comprises an integral tubular projection extending from the inner surface thereof towards the printed circuit board so as to surround at least one electronic component thereon;
• wherein the inner surface and a rim of said integral tubular projection are electrically conductive so that the tubular projection forms part of a Faraday cage around said at least one component;
• wherein the tubular projection includes a recess in the rim thereof which does not make contact with the printed circuit board;
• wherein the printed circuit board comprises at least first and second conductive layers, the second conductive layer being located further from the tubular projection than the first conductive layer, wherein the at least one component is mounted on the first conductive layer, and wherein a plurality of electrically conductive vias through the printed circuit board electrically connect the rim of the tubular projection with the second conductive layer;
• wherein the plurality of electrically conductive vias are positioned along a boundary which substantially surrounds the component;
• and
• wherein said boundary and said plurality of electrically conductive vias deviate from the rim of said integral tubular projection in a region where a signal cable enters the Faraday cage.