Abstract: A creosote buildup detector utilizes a change in temperature between two sensors. The temperature between the two sensors changes as the creosote builds up. This change in temperature is established by providing an electric heater to heat one of the sensor supports. A temperature comparator senses the change in relative temperatures between the two sensors and annunciates when a sufficient creosote buildup has occurred to indicate that cleaning the chimney is necessary.

Abstract: Disclosed is a system for accurately sensing the temperature of articles being heated in a microwave oven. Basic structural elements of the invention are a housing that defines an oven chamber, a door providing access thereto and an energy source for transmitting microwave energy into the chamber. A temperature responsive sensor is positioned within the chamber and is adapted to sense the temperature of articles being heated therein. Enclosing the sensor is an elongated sensor body formed of an electrically conductive material so as to provide a shield for microwave energy and having a length that establishes therfor a detuned antenna condition at the microwave transmission frequency of the source. An electrical control circuit is coupled between the source and the sensor and controls energization of the source in response to temperature levels sensed by the sensor.

Abstract: A self-monitoring heat tracing system including a heating conductor, a monitor conductor, and a control circuit which monitors the integrity of the heat tracing conductor and provides alarm signals to indicate abnormal temperature conditions in the heating system or discontinuities in the monitor circuit.

Abstract: A measuring cable with spaced measuring stations is laid. The measuring stations each have a sensor whose electrical conductivity depends on an ambient variable such as temperatures light etc., each sensor is provided with a control arrangement which, due to a transmitted signal from a control center, connects its sensor to a constant current source and returns a signal indicative of any voltage change dependent on the variable ambient which signal is measured by the control center. The measuring cable is divided into sections each having a selectable circuit which can be selected individually by the control center. A clock pulse signal is transmitted to all measuring stations but is only active for the cable section which has been selected. In this manner, the cable section can be chosen as desired, the time required for the control center to have access to certain measuring stations is shortened and semiconductor switches can be used because measurements are only made in the steady state.

Abstract: Disclosed is an electrical connection system for a microwave oven including a chamber defining a housing, a source for transmitting microwave energy into the chamber, a turntable rotatably mounted within the chamber and defining stations for receiving articles to be heated and a drive mechanism for producing rotation of the turntable. A control circuit controls energization of the source in response to signal outputs from temperature responsive sensors positioned in the heating stations. The rotary coupling includes a stationary portion mounted on the housing and having stationary contacts connected to the control circuit and a rotary portion mounted on the turntable and having rotary contacts connected to the sensors and slidably engaging the stationary contacts during rotational movement of the turntable.

Abstract: A conventional lamp having a tubular yoke around the bulb that supports a lamp shade is converted into a security system by a simple physical electrical and mechanical coupling of two modules, eliminating wiring and installation tools. The first module, referred to as the bulb module, is screwed into the bulb socket and contains line voltage components and supports the light bulb; the second module, the probe module, contains low voltage circuitry, an audio alarm, a pigtail power connector, a light switch, and an extendable sensor probe. Upon sensing an abnormal condition, such as smoke, the bulb flashes on and off and a warning sound is provided by the audio alarm, giving both visual and audio alarm in one self-contained unit.

Abstract: A system for detecting fires in a barn or similar structure includes rate of rise heat detectors and temperature sensing cable. Upon detection of a predetermined rate of rise or a predetermined temperature the control circuitry of the system produces an output signal that activates an audible alarm mounted outside the barn. The control circuitry also produces an FM signal that travels through the power lines servicing the farm. The FM signal activates an audible alarm plugged into an electrical outlet in the home.

Abstract: A fire, temperature or heat detection system is disclosed which comprises a cable having at least two conductors separated by insulation whose electrical characteristics vary with temperature, and means connected to the conductors of the cable for detecting variations in the electrical characteristics of the insulation.

Abstract: A heat sensing cable is provided for use in an alarm and/or fire extinguishing system, which is capable of responding to the presence of fire, or excessive heat, and to sound an alarm, actuate fire extinguishing sprinkling equipment, operate other fire extinguishing means, or to perform other emergency functions. The heat sensing cable of the invention comprises two or more multi-strand single conductor plastic coated insulated wires twisted together in a spiral manner, and which are placed under tension when in use. Each insulated wire in the multi-conductor heat sensing cable of the invention consists of a single multi-strand conductor of low electrical resistance, formed of copper or other suitable conductive material, and having any particular gage to suit any particular application.

Abstract: The present invention is directed to the method and apparatus for monitoring the electrical resistance characteristic of tree tissue which undergoes a step change of resistance at the "freezing" point. The resistance of the tissue is monitored by converting the resistance magnitude sensed to an electrical signal whose frequency is controlled in accordance with the magnitude of the sensed resistance. The frequency of the electrical signal is detected and a control signal generated in accordance with a predetermined frequency change in a set time period which is accordingly indicative of the step change of tissue resistance. The control signal is thus adapted to activate an alarm device or provide some other indication so that precautionary measures can be taken to protect trees, and more particularly fruit bearing trees from crop damage.