Abstract: A water sensor and activation assembly including a paper element to sense the presence of water leaks from appliances such as clothes washing machines, refrigerator ice makers and the like, and to cause an associated water shutoff valve to turn off the source of water leakage. The water sensor, in conjunction with the shutoff valve, operates without any electrical power requirement. The design allows the water sensor to operate in a high humidity environment.

Abstract: A clog resistant, pilot operated pilot valve having two fluid paths, one path for fluid flow from the valve input to the valve output, and the second path for fluid flow through input and output pilot apertures. The opening and closing of the pilot apertures controls the flow of fluid between the input and output of the pilot valve. A clog resistant pilot operated valve in which fluid flows through the pilot fluid path only during the time of transition from an valve open to a valve closed condition, or vice-versa, thereby reducing the probability of failure due to contaminants blacking the pilot activation path. A clog resistant pilot operated valve in which the plunger, used to open and close the pilot fluid paths, is ribbed in construction to reduce the probability that contaminants will cause seizure of the plunger movement.

Abstract: A velocity reduction system for use in retractable screen door installations. A pneumatic cylinder is located within a moveable housing that is used to capture the leading edge of the screen material. The pneumatic cylinder contains a moveable weight that is fastened to the screen doorframe using a cable. Incorporated within the weight is a check valve that restricts the passage of air when the weight is being pulled in an upward direction, associated with the opening of the screen door. The size of an aperture at the lower end of the pneumatic cylinder, along with the strength of the retracting spring that rewinds the screen material, control the velocity of air entering the pneumatic cylinder and therefore the opening speed of the screen door.

Abstract: A pilot operated shutoff valve system with leak detector for automatically shutting off a water supply to appliances such as a clothes washing machine, dishwashing machine, sink, toilet, or refrigerator equipped with an ice maker, comprising a sealing member movable within said valve body between an open position wherein the sealing member does not block main fluid flow, and a closed position wherein the sealing member blocks main fluid flow.

Abstract: A latched, spring loaded valve having a water sensor and an activation mechanism shuts off water supply, when a water leak is detected, to specific application as cloths washing machines, dishwashing machines, sinks, toilets, and refrigerators equipped with ice makers. The shutoff valve system with leak detector has a sealing member movable with a valve body between an open position and a closed position wherein the sealing member blocks fluid flow.

Abstract: An automatic shutoff valve system for installation for instance in the water supply line to a hot water heater includes a sensor to detect leakage electrically by sensing moisture, and then shutting off the supply line in response. The valve mechanism includes a spring loaded ball valve normally latched in the open position which is unlatched and hence closes by the contraction of a BioMetal.TM. wire which activates a torsion spring to rotate the ball valve. The valve is controlled by a microprocessor which includes self test features, and the valve system may operate for a year or more on battery power.

Abstract: A low friction ball valve used for instance in an automatic shutoff valve system. The valve mechanism includes a spring loaded ball valve normally latched in the open position which is unlatched and hence closes in one version by the contraction of a BioMetal.TM. wire which activates a torsion spring to rotate the ball valve. When the valve is open, the ball inside the valve rests on rollers so that the ball is held slightly away from the seal of the valve located in the valve body. Closing the valve causes the rollers to snap into detents in the ball, and the ball then comes into firm contact with the seal.

Abstract: A digital inclinometer for detecting the angular orientation of a structure includes a rotatable encoding disk on which is mounted a horizontal tilt sensor. The inclinometer electronically measures, by angular indices on the encoding disk, the difference between the angular orientation of the device and a horizontal orientation. In another embodiment, the encoding disk is rotated by a stepper motor and the number of steps are electronically counted to determine the angular orientation. The inclinometer has a digital display.

Abstract: An electronic level for determining the angular orientation of a structure, where the error angle between actual and desired angular orientation of the structure is indicated by a variable signal perceptible to the user.

Abstract: An improved motor speed control system for high speed, high resolution motor control applications such as centrifuges is presented. A proportional, or proportional and integral motor control system is provided with improved circuitry which uses digital phase lock techniques to generate a speed difference signal that accurately reflects the difference between the actual and desired speed of the motor. This speed difference signal is used to adjust the speed of the motor until the actual and desired speeds become approximately equal to one another. An error integrating network may then be enabled to eliminate any remaining difference between actual and desired speed, thereby assuring a negligible speed error.

Abstract: A function generator responsive to clock pulses for developing an analog signal in the form of a digitally approximated parabola.

Abstract: A portable device for locating a wall stud or similar object positioned behind a wall surface comprises means for detecting a change in the dielectric constant of the wall due to the presence of a stud or similar object and, in combination therewith, means for detecting the presence in the wall of a source of alternating current. In addition, a display is provided for visually indicating the presence of a source of alternating current in the wall in response to a signal from the means for detecting. The circuit also includes an amplifier to compensate for variations in characteristics of the electrical components used in the structure and an improved circuit for bleeding a bias charge used to calibrate the device when the device is shut off while preventing this charge from being bled when the device is turned on, and structure for indicating to the user that the device is being calibrated.

Abstract: A switching voltage regulator is provided for coupling a source of AC potential to a DC load. Thyristor full wave rectifier means provide a source of DC potential which is connected to the load through an inductance in series with the load. The input of the inductance is shunted by a commutating diode which provides a path for the inductive current when the thyristor means are in the nonconducting phase of their operating cycle. Circuit means are provided to reverse bias the commutating diode in advance of each conduction cycle of the thyristor means. As a consequence, the level of RFI conducted to the AC power line is significantly reduced.

Abstract: In accordance with the present invention, there is provided an air driven centrifuge including a rotor housing having an access door in which there is mounted the illuminating and sensing elements of a photo-optical tachometer with the elements so constructed and arranged that they are positioned over the rotor when the door is in a closed position. There is also provided a rotor cover having at least a portion of its surface conditioned to alternately absorb and reflect incident light, and digital display means to display the rotor speed in R.P.M.

Abstract: A method and apparatus for detecting the absence of a coded overspeed disk used to indicate the maximum design speed of a rotor which is rotatably connected to a high speed centrifuge. Two donut-shaped coded disks, one mounted on the drive shaft on the centrifuge and the other mounted on the centrifuge rotor are utilized. Optical emitter sensor assemblies are used to produce speed control and overspeed signals. By sensing the light reflected back to the optical sensor from the drive system hub, the rotational speed of the centrifuge is indicated. By sensing the light reflected back to the optical sensor from the overspeed disk mounted on the rotor, the rotation of the rotor is detected. In the absence of an overspeed disk, the speed control frequency will exceed that of the overspeed disk.

Abstract: A portable sensor adapted to be moved along a wall to indicate a change in the dielectric constant of the wall thereby to signal the presence of a wall stud within the wall. The sensor incorporates a capacitor plate positioned adjacent the surface in contact with the wall and a circuit for detecting any change in the capacitive charge on the capacitor. Any change in capacitive charge as the sensor is moved along the wall is due to a change in the dielectric constant of the wall because of the presence of a wall stud behind the wallboard. The sensor visually indicates any change in the dielectric constant in a manner to permit selection of the center of the change in dielectric constant thereby indicating the center of the wall stud. An additional feature of the circuit permits automatic calibration of the sensor to a level corresponding to the dielectric constant of the wallboard so that any change in the dielectric constant of the wall due to the presence of a stud is readily observable.

Abstract: A closed-loop induction motor power control employs a novel digital phase-locked loop which maintains a constant torque over all contemplated motor speeds. Digital processing means incorporating a novel digital phase detector employing an exclusive OR function provides a correction signal to a voltage controlled oscillator controlling the speed of the induction motor. The correction signal provided thereby is proportional to the difference between the desired slip frequency and measured slip frequency. The closed loop control system is capable of generating a constant slip frequency, either positive or negative, with respect to the rotor speed. The system is also capable of automatic shutdown and rapid response to variable-inertia loads thereby minimizing the possibility of excessive power converter current which could result in an overload shutdown as may occur during motor start up, rapid motor acceleration, or rapid increase in inertial loading.

Abstract: A combination switch for use in a standard wall receptacle for controlling the range of power supplied to the receptacle and also for turning on and off the power to the receptacle in accordance with a predetermined time sequence.