Abstract: A noise cancelling microphone for location inside an apertured mouthpiece region of a telephone handset comprises a housing with a face for securement in contact with the inside of the mouthpiece region. A cavity accommodates a vibratable diaphragm. A first sound path is provided to a front surface of the diaphragm by way of an opening in a central region of the face of the housing and apertures in a central portion of the mouthpiece region of the handset. A second sound path, physically separated from the first, is provided to a rear surface of the diaphragm by way of an opening in an outer region of the face of the housing and apertures in an outer portion of the mouthpiece region. The separated sound paths are extended by securing an upstanding member, such as a hollow truncated cone, externally on the mouthpiece region to separate the central and outer apertures.

Abstract: A variable electrical resistance device for monitoring displacement of a mechanical component such as a vehicle road wheel suspension system having a housing; an electrically resistive track and conductive slip ring on a support in the housing; electrically conductive wipers on a rotatable carrier provided with a spindle for coupling to the component. The wipers traverse the resistive track and the slip ring respectively. The support is mounted on springs or flat strips of resilient metal, so as to be displaceable away from and towards the wipers. A solenoid, of double-acting type or acting in association with the bias of the springs, has an armature operating to effect displacement of the support away from and towards the wiper whereby contact between the wiper and track may be broken, or the contact pressure therebetween reduced, when monitoring is not required, thereby prolonging the life of the wiper and track assembly.

Abstract: A strain gauge or transducer is provided incorporating a supported film electrical resistance element whose electrical resistance varies as a function of applied mechanical strain and is provided with electrically conductive terminals. The resistance element comprises a dispersion of electrically conductive or resistive particles in an organic polymer together with an optional electrically insulating filler material. In a particular embodiment, the resistance element is supported on a member of anodized aluminum.