Abstract: An incubator for laboratory use which includes a housing defining a thermally insulated inner chamber having a controlled gas atmosphere. Devices for sensing characteristics of the incubator chamber atmosphere, and for conditioning the atmosphere, are positioned in a gas recirculation path outside the incubator chamber. The gas atmosphere of the incubator chamber circulates from a chamber outlet in an upper portion of the chamber, through the recirculation path, returning to the incubator chamber through a chamber inlet in a lower portion of the chamber. Included in the recirculation path are a blower for recirculating the chamber atmosphere, a filter, a CO.sub.2 sensor, and a humidifier. A microprocessor-based controller is responsive to the output of the CO.sub.2 sensor to effect the addition of CO.sub.2 to the recirculating gas to maintain a selected CO.sub.2 level in the chamber atmosphere. Upper and lower diffuser plates in the incubator chamber define upper and lower plenums, respectively.

Abstract: A dual probe interactive, control system for accurately controlling the temperature within a specified area has a controlling temperature probe located for fast response times and used in association with a controllable setpoint for modulating a heating/cooling source. An indicating/reference temperature probe is also placed in the same enclosure at an optimum location for indicating actual temperature. The actual temperature is compared to the desired temperature to detect any droop or offset and the controllable setpoint is then adjusted accordingly.

Abstract: A time multiplexed sensor monitoring system. A plurality of remote sensor units are connected to a central control unit by a two-wire bus line. Power is supplied to the remote unit sensors by the central control unit. Synchronization of the remote units is provided through momentary interruptions in the power supplied to the remote sensor units. The use of a single two-wire bus line for both application of DC signals to the respective remote sensor units and communication of data from the remote sensor units to the central control unit is facilitated by use of double tone multi-frequency (DTMF) signalling techniques.