Abstract: An electrical circuit provides a variety of stable and reliable bias voltages to accommodate the bias requirements of various sensor types. The electrical circuit comprises a programmable analog circuit capable of maintaining a plurality of programmable threshold voltages and producing a plurality of intermediary voltages. Such voltages act as an input to a differential amplifier that outputs a bias voltage within a range consistent with said programmable threshold voltages. The bias voltage is further conditioned by a conditioning amplifier that further stabilizes the bias voltage to an attached sensor.

Abstract: A gas detection apparatus having a microprocessor control circuit mounted within a housing chamber which is operable for processing input signals associated with measured gas levels and generating output signals corresponding to same to the output port. An interchangeable electrochemical sensor device is removably disposed within the chamber via an access opening of the housing, the sensor being operable for sensing and measuring gas levels and generating the input signals to the microprocessor circuit. An elastomeric connector unit is removably and sealingly disposed between interfacing contact surfaces of the sensor and control circuit via the access opening. The connector unit provides a conductive path between the microprocessor circuit and the sensor device and electromagnetic shielding therebetween.