Abstract: A three-wire sensor interface for field wiring of conventional on/off type control sensors that delivers power to the sensor, provides a normally open control output from the sensor and, concurrently, provides a normally closed control output from the sensor. The sensor interface includes a plurality of external terminals including a normally open external terminal for electrically connecting to zero, one, or more normally open load devices to control the operation of the normally open load device, and a normally closed external terminal for electrically connecting to zero, one, or more normally closed load devices to control the operation of the normally closed load device. A plurality of interface terminals are preferably electrically coupled between the sensor interface and the sensor and include a normally open control terminal and a normally closed control terminal.

Abstract: A proximity detection system for detecting the proximity of conventionally hard-to-detect materials having a complex permittivity and/or a complex permeability is disclosed. The system includes an oscillator for producing an output signal, the oscillator having a transistor with an open and a closed loop gain and a base-emitter junction that rectifies resonant signals at the collector to produce the output signal. The oscillator includes negative feedback including a resistive element coupled to the emitter for reducing the sensitivity of the closed loop gain to variations in the transistor's open loop gain and a capacitive element coupling the resistive element to the collector for stabilizing the frequency of the oscillator. The detection system further includes a sensor coupled to the oscillator for varying the level of the oscillator output signal in response to certain electrical properties of the material.

Abstract: A three-wire sensor interface for field wiring of conventional on/off type control sensors that delivers power to the sensor, provides a normally open control output from the sensor and, concurrently, provides a normally closed control output from the sensor. The sensor interface includes a plurality of external terminals including a normally open external terminal for electrically connecting to zero, one, or more normally open load devices to control the operation of the normally open load device, and a normally closed external terminal for electrically connecting to zero, one, or more normally closed load devices to control the operation of the normally closed load device. A plurality of interface terminals are preferably electrically coupled between the sensor interface and the sensor and include a normally open control terminal and a normally closed control terminal.

Abstract: A sensor package for proximity detectors adapted for use with materials having a significant angle of repose. The sensor package includes a hollow housing defining a cylindrical main body adapted to house proximity detection circuitry and a non-planar tip disposed on one end of the housing adjacent the main body. The tip portion is preferably tapered in its diameter from a dimension generally equal to the diameter of the main body to a dimension less than the diameter of the main body. The tip is adapted to house a sensing element electrically coupled to the proximity detection circuitry and disposed on an inner bottom surface of the tip portion. Preferably, the taper of the tip is selected to substantially match the angle of repose of the materials to be sensed, and may take on a wide variety of shapes including cone, frustum, pyramid, round and hemispherical.

Abstract: A user input device is disclosed adapting the electronic components of a time-domain reflectometry material level sensor to replace traditional user input devices such as push-buttons, control knobs, and variable sliders. An electrical conductor is arrayed beneath an input panel, such that when a high permittivity or high conductivity material is placed in proximity to the conductor, the characteristic impedance of the conductor is altered at that point, reflecting electronic pulses transmitted through the conductor. The reflected electronic pulse is received by the associated electronics, and the position of the material along the conductor subsequently determined. By segmenting the conductor into virtual regions, each corresponding to an individual "button", discrete input may be received by the device based upon the placement of the material within specific virtual regions.

Abstract: This oil level control device is for a refrigeration system, the control device being attached between the compressor and the oil supply. The control device includes a housing having an inlet communicating with the oil supply and an outlet communicating with a compressor sump; and a solenoid valve controlling flow from the oil supply into the compressor sump. A sensing chamber having a fixed probe providing a proximity detection system detects the oil level in the sump and responds to a change in the complex permittivity of the oil as the oil level rises and falls to generate a signal that controls the supply of oil to maintain the oil level in the compressor. Circuitry is provided having an input connected to the output of the sensor and an output connected to the solenoid valve.

Abstract: The disclosed system comprises a testing system which measures the stability of a moving target indicator radar transmitter. It automatically measures the imperfections of its internal in-phase (I)/quadrature (Q) demodulator, and it consists of a control computer, a synchronizer, a frequency synthesizer, an IQ demodulator, a low noise amplifier and a waveform recorder. A unit under test is inserted across the test set for measurement and calibration. The system set has the following features: (a) An automatic calibration routine that requires a tunable RF source. This source provides the RF drive to the UUT. (b) A discontinuous analog to digital (A/D) sample clock that has a precise controllable relationship with the RF pulse. The A/D sample clock samples only during the presence of the RF. (c) A method for computing stability using a table of amplitude and phase weighting coefficients and pulse positions. This table is generated by the user and any desired combination of values is possible.