Abstract: In a data transmission system having a main controller for transmitting polling messages in a polling sequence and a plurality of terminal controllers responsive to a polling message to transmit data to the main controller, the finally polled terminal controller transmitting an END code for informing the main controller of the end of data transmission.

Abstract: An ionization detector for detecting a vapor constituent uses a first mode of operation in which only the vapor carried by ambient air is conducted through the ionization detector and a second mode of operation in which the outlet line from the ionization detector is connected to direct the exhaust gas flow from the ionization detector through a desiccant cartridge to remove humidity from the gas flow exiting from the ionization detector. The dehumidified gas with the constituent to be detected is then reintroduced into the input of the ionization detector to provide an improved sensitivity of the detector to the constituent. An alternate first and second operating mode cycle is provided to produce an increased output level of constituent detection from the ionization detector. This increased output level can be arranged to initiate an alarm operation for the vapor constituent being detected even at a very low constituent concentration.

Abstract: A dimming system for fluorescent tubes wherein counter electromotive forces generated during switch off of the tubes are used to maintain filaments of the fluorescent tubes heated during switch off periods of the tube, the dimming system having source terminals for connection to a source of power, the power having zero phases, load terminals for connection to the fluorescent tubes, a switch connected to the source terminals and to the load terminals for controlling the supply of power to the load terminals, a zero phase firing circuit connected to the switch for energizing the switch to supply power to the load terminals at the zero phases, a phase turn off circuit connected to the switch for deenergizing the switch to switch off power to the load terminals at phases of the power other than the zero phases, and a switch off filament heating control circuit connected to the switch for converting counter electromotive forces generated at switch off of the tube into power for supply to the filaments during switc

Abstract: An electrode system for an electrochemical sensor has a plurality of electrically conductive sensing segments isolated from each other and mounted on a support substrate formed from a chemically inert encapsulation material. The sensing segments are unencapsulated and are each coated with respective ones of ion conducting sensing materials to characterize each of the segments except for one of the segments which is uncoated and is arranged to be used as a reference electrode. The outer surface area of the sensing materials and the reference electrode is coated with a layer of a nonaqueous electrolyte which serves as a sorption/desorption medium. The electrolyte, in turn, is covered by a semipermeable thin film membrane secured at its peripheral edge by an O-ring to the support to form a fluid seal. Electrically conductive leads are connected to respective ones of the sensing surfaces, and a temperature measuring device is provided in the electrode structure for temperature compensation.

Abstract: A sensor communication system uses a shared analog signal to duty cycle converter for producing a comparison between a predetermined free-running triangular waveshape and a selected output signal from a plurality of analog signal sources such as process sensors, to convert the amplitude of the analog signal to a variable duty cycle signal. The variable duty cycle signal is subsequently converted to a digital signal which may be represented by a count stored in a counter counting clock pulses during the occurrence of the pulse width waveshape of the variable duty cycle signal. The digital signal is utilized as a digital word by a microprocessor operating in accordance with a stored program to produce a characterized digital output signal for use in a communication after conversion to a 4-20 ma control signal for communication and control in an industrial process control system.

Abstract: A flow sensor having adjustable sensitivity includes a differential pressure sensing element located in an internal compartment within a rotatable cylinder. The compartment is connected between diametrically opposite fluid ports on the surface of the cylinder by fluid channels. In one embodiment, the sensor is located on a diaphragm partitioning the compartment into a first and a second chamber with the sensor being responsive to a distortion of the diaphragm induced by a differential pressure. In a second embodiment, the sensor is a flow sensor and is arranged to monitor a fluid flow through the compartment induced by a differential pressure. The cylinder is rotatable on an axis at located right angles to a fluid flow thereacross whereby the ports are selectively located at a desired angle with respect to the fluid flow path. The cylinder is located within a fluid-tight housing having a fluid inlet and a fluid outlet arranged to direct a fluid being monitored by the sensor around the cylinder.

Abstract: A humidity sensor operates with a capacitive sensor element (C.sub.S) which is arranged in one branch of a free-running multivibrator (MV), whereas a reference capacitor (C.sub.ref) is arranged in the other branch of said multivibrator. Both output signals (U1, U2) of said multivibrator (MV) are averaged by means of RC elements (R3, C1; R4, C2) and supplied to a differential amplifier (DV), the output signal (Ua) of which changes the operating voltage (U.sub.B) of the multivibrator (MV), and therefore, linearizes the characteristic of the capacitive sensor element (C.sub.S).

Abstract: A system for providing modulated air flow control in response to an on-off thermostat having an on-off thermostat, a self-returning, slow moving motor connected to the thermostat for moving in a first direction when the thermostat is on and moving in a second direction when the thermostat is off, a damper motor adapted to drive a damper, and a controller driven by the self-returning, slow moving motor and connected to the damper motor for modulating air flow in response to the on-off thermostat.

Abstract: A wireless superheterodyne receiver is provided having an antenna for receiving wireless transmissions, a preamplifier having an input connected to the antenna and an output, a crystal filter having an input connected to the output of the preamplifier and an output, a demodulator having an input connected to the output of the filter, the demodulator having a single mixer, an oscillator having a second crystal connected to the single mixer of the demodulator wherein the demodulator supplies at an output a demodulated signal based upon the wireless transmissions.

Abstract: A variable gain amplifier is adjusted to maintain its amplification within a linear range, i.e., to prevent saturation of the amplifier, by utilizing the output of an analog-to-digital converter, which is arranged to convert an analog output of the amplifier to a digital representation, by a digital computer to effect the gain change of the amplifier. Concurrently, the output signal of the digital computer representing the output signal from the analog-to-digital converter is modified to produce a system output signal based on a constant overall gain of the system which is equivalent to the highest available gain from the amplifier. Thus, while the amplifier gain is adjusted by the computer in response to the amplitude of the input signal, the overall system gain is maintained at a level which would be available at the highest amplifier gain. The digital output of the system can subsequently be utilized as a control signal either directly or after a digital-to-analog conversion.

Abstract: The method for spacing the folds of a folded filter media assembly includes the steps of separating the folds of the filter media by the use of the tapered assembly comb having uniformly spaced teeth and subsequently inserting a rigid divider into the separated and spaced media folds to produce a uniformly spaced filter media. The comb can be discarded after the divider is inserted, and, accordingly, the comb is made of an inexpensive material having a desired degree of rigidity for handling, e.g., cardboard. The uniformly spaced filter media assembly is inserted into an operative position for filtering, e.g., as an air filter.

Abstract: A distributed load processing system for shedding and/or adding loads controlled by a plurality of processors for maintaining power demand by the loads below a predetermined amount including a common communication channel, a plurality of processors connected to the common communication channel, a demand meter for sensing the power consumption per sample period so that the power consumption per sample period can be transmitted to all of the processors, wherein each processor compares the demand limit established for the system to the projected power per interval being consumed, and for shedding and/or adding its associated loads based upon this comparison to maintain power consumption per interval below the demand limit.

Abstract: An averaging temperature responsive device having a hollow elongated member, a plurality of holes substantially along the length of the member, the plurality of holes decreasing in area from the hole near the end at which the member is mounted to the hole at the other end of the member, an exhaust opening at the second end of the member for permitting air moving through the duct which enters the plurality of holes to be exhausted from the inside of the member, and a temperature responsive element for sensing the average temperature of air moving through the member.

Abstract: A two-stage solenoid valve uses a pair of stacked coaxial armatures separated by a predetermined gap which is maintained by a first spring therebetween. A coaxial connecting rod extends between a first armature and the second armature and is attached to the first armature. A head on the unattached end of the rod bears against a bottom surface of a recess in the second armature to limit the expansion of the first spring. A second spring is arranged to contact the head of the rod and to extend therefrom to a fixed plug in the end of a cylindrical housing surrounding the first and second armatures. The first armature is provided with a fluid sealing surface on a first end for sealing an adjacent fluid port in the valve in response to the spring force exerted by the second spring. A first and a second solenoid coil assembly are coaxially stacked to surround the cylindrical sleeve housing adjacent to respective ones of the first and second armatures.

Abstract: A data distribution apparatus for controlling the distribution of data signals from field mounted devices to a central processor includes a backplate having wiring connected thereto between the backplate and the field mounted devices and between the backplate and the data processor. A cover for the backplate includes a printed circuit board mounted thereon with an electrical connector extending therefrom. The cover connector is arranged to mate with an electrical connector board mounted on the backplate to selectively connect the printed circuit board on the cover to electrical circuits connected to the connector board on the backplate. Thus, the removal of the cover which is keyed to the backplate to ensure a correct orientation thereof on the backplate is effective to interrupt the electrical connections provided by the printed circuit board among the wiring connected to the electrical connector board and vice versa.

Abstract: A method of producing a fluid-tight seal between a thin, flexible member and a support including the steps of providing a moat for receiving excess braze material on an external surface of a member support and a dam adjacent to the moat to confine the excess braze material to the moat and having a height above the bottom of the moat to accommodate a brazing of the member to the external surface, positioning the member to extend across the dam and the surface while contacting only the top of the dam and brazing the member to the surface while maintaining the contact between the top of the dam and the member to uniformly support the member.

Abstract: An electromagnetic relay having a dual acting armature has a U-shaped armature with two divergent legs. The armature is pivoted on one of the legs with the pivoted leg being arranged adjacent to an electromagnetic field producing structure including an electrically energizable coil. A first movable electrical contact carrying means is arranged to cooperate with a first one of the legs of the armature to produce a motion of a first electrical contact between a first and a second position in response to an energized and a non-energized state of the coil, respectively. Concurrently, a second movable electrical contact carrying means is arranged to cooperate with the other or second leg of the armature to produce a motion of a second electrical contact between a first and a second position in response to an energized and deenergized state of the coil, respectively. The coil is located in the bight of the U-shaped armature with the pivoted first leg being urged by a spring away from the coil.

Abstract: A pneumatic valve uses a body made of a synthetic material with a plurality of internal fluid ducts opening onto a face of the body via respective orifices. A metal plate is arranged in contact with the aforesaid face and is provided with sockets aligned with respective ones of the duct orifices and each containing a tapped hole capable of receiving a threaded connecting pipe. Resilient O-rings are used to provide a fluid-tight seal between the sockets and the ducts.

Abstract: A lighting control system is provided which utilizes a light responsive sensor means and a control system to respond to the skylight illumination while rejecting direct sunlight as a control parameter. The skylight illumination level is used to control lighting power controllers that can dim interior lighting equipment in a defined pattern to maintain a uniform light level at a work surface and to conserve electrical energy.

Abstract: A dual input watchdog timer for a processor having a dual input circuit with first and second inputs and an output, the first and second inputs receiving signals from different software modules of the processor and the output for supplying a reinitialization signal to the processor if the dual input circuit improperly receives the signals to its inputs within a predetermined amount of time.