Abstract: A control device including a switch with a ferromagnetic armature moving between a first position and a second position. The armature actuates a plunger that causes the switch to snap from an open position to a closed position. An energy-storing member may be positioned adjacent the ferromagnetic armature, the energy-storing member moving a magnet between an attracting position and a non-attracting position based on a temperature of an environment surrounding the energy-storing member. When the energy-storing member positions the magnet in the attracting position, the magnet causes the armature to snap from the first position to the second position, thereby actuating the plunger and causing the switch to snap from the open position to the closed position. A ferromagnetic backstop may also be positioned adjacent the magnet and coupled to the energy-storing member to hold the magnet and the energy-storing member in the non-attracting position.

Abstract: A damper unit for an air circulation system. The damper unit includes an air flow opening, a damper vane for opening and closing the air flow opening, and a motor for moving the damper vane between the open and closed positions. The damper also includes at least two ports, each port being operable in an input and an output mode. When a control signal is received on one port, the signal is sent out on the other port, and vice versa. The ports can be identical in shape to receive the same shaped plug.

Abstract: Systems and methods for providing a current control loop for an actuator. A typical system includes a current command controller setting a command current, the current command controller being coupled to a drive circuit used to drive the actuator and a sampling module sampling a motor current of the actuator. The system also includes a summation module calculating a current error based on the motor current, the current error being calculated by subtracting the motor current from the command current. The current error is used to compensate for an error in the motor current of the actuator. The sampling module can include a switch and a capacitor coupled in parallel with the resistor when the switch is on, a charge on the capacitor being proportional to the voltage drop across the resistor. Methods for setting a maximum control current and for providing the current control loop are also illustrated.

Abstract: A system has a plurality of nodes communicating with each other on a serial data path using dominant and recessive signal levels. A dominant signal level sent on the data path by any of the nodes creates a dominant signal level on the data path irrespective of the number of recessive signal levels sent by other nodes. The dominant and recessive signal levels form a series of bits organized into messages by the nodes. Each sending node senses the signal level on the data path bit by bit, and if different from that sent by that sending node, halts further sending of signal levels by that sending node. A priority value generator in each node provides a priority signal encoding a value whose magnitude indicates a relative priority. A message priority module in each node receives the priority signal, and stores the priority value in predetermined leading bits of the message to be sent.

Abstract: A system, apparatus, and method for preventing thermal cycling of a ballast coupled to one or more lamps. A monitor circuit is provided to monitor for activation of the ballast's thermal protection mechanism. Such monitoring may include monitoring of the ballast's thermal protection mechanism itself, or monitoring lamp current and ambient temperature in the vicinity of the ballast to determine that the ballast's thermal protection mechanism has been activated. Power to the ballast is temporarily disabled when the ballast's thermal protection mechanism has been activated, thereby preventing thermal cycling of the ballast, and consequently of the lamps, when power to the ballast has been removed.

Abstract: A system, apparatus, and method for allowing LED operation in circuits operating with power supply levels that are below the forward voltage limits of the LED. A first level of a modulated voltage signal is applied to charge a voltage increasing component in a first phase of operation. A second level of the modulated voltage signal is then summed with the voltage stored across the voltage increasing component to provide adequate forward potential across Light Emitting Diode (LED) for illumination. The second level of modulated voltage is also used to provide a source of constant forward current to be conducted by LED when in its luminescent state.

Abstract: An actuator including an electric motor driven by a drive circuit powered by a power source, and a load coupled to the electric motor. The actuator further includes a spring biasing the load to a first position, and a microcontroller coupled to the electric motor to commutate the electric motor. Upon failure of the power source, the spring returns the damper to the first position, and, as the spring returns the load to the first position, the electric motor is spun to generate electricity that is used to power the microcontroller. The microcontroller can govern a speed at which the spring returns the load to the first position. In addition, a potentiometer can be used to indicate when the load approaches the first position so that the microcontroller can slow the speed of return prior to the load reaching the first position.

Abstract: A circuit in accordance with the invention includes a safety switch device coupled with, and between, a thermally activated voltage source and a primary switch. The circuit also includes a safety switch control circuit coupled with the safety switch device and a controller circuit; and a voltage generation circuit for turning on the safety switch device. The voltage generation circuit is coupled with the safety switch control circuit, the controller circuit and the safety switch device, such that the controller circuit substantially controls operation of the voltage generation circuit, the safety switch control circuit, and a primary switch circuit that includes the primary switch.

Abstract: An actuator is provided having an electric motor that generates a back emf. The actuator also includes a control system for controlling the speed of the electric motor. The control system includes a controller and circuitry for allowing the controller to sample the back emf of the motor. The controller uses the sampled back emf as feedback representative of motor speed for use in controlling the speed of the motor.

Abstract: A fluid flow control valve uses a servo valve to control the pressure in a main diaphragm chamber defined by a main diaphragm. The main diaphragm carries a main valve element that assumes either a low flow or a high flow position relative to a valve seat depending on which of two states the servo valve is in. When the servo valve is in the one of the two states creating the low flow position of the main valve element, the main diaphragm chamber pressure is regulated by a pressure divider comprising two flow restrictors in series connection between the inlet and outlet chambers of the valve. When in the other of the two states, the servo valve disables the pressure divider and allows the main diaphragm chamber pressure to reach the outlet pressure. The disclosure shows two versions of the invention. One version of the valve enters its low flow state when the servo valve is closed, and the other when its servo valve is open.

Abstract: Method and apparatus for testing the operation of an alarm for a ventilated enclosure, such as a fume hood or bio-safety cabinet. Flow of gas being exhausted from the enclosure may be adjusted to a known value below or above a threshold value at which the alarm provides an indication that flow is unacceptably low or high. Adjustment of flow to the known value may be performed without requiring a manual measurement of flow, e.g., by performing a traverse in a duct leading from the enclosure.

Abstract: A gas conversion assembly generally has a gas inlet and a gas outlet. The assembly includes a control mechanism for regulating the flow of gas from the inlet to the outlet. The control mechanism is constructed and arranged to adjust from regulating the flow of a first gas to regulating the flow of a second gas. The control mechanism has an actuator for switching the control mechanism from its first arrangement for regulating a first gas to its second arrangement for regulating a second gas.

Abstract: A system for controlling temperature in an enclosure operates in a low heat or a high heat mode with flame always present. The presently intended use is for providing a cooking grill with a controlled temperature cooking space. An electrically controlled valve having high flow rate and low flow rate settings is interposed in the fuel line for at least one of the burners in the grill. A temperature sensor signals cooking space temperature to a controller that may be a microprocessor. The system includes a keyboard allowing the user to communicate a selected set point to the microprocessor and the microprocessor communicates status to a display. The microprocessor selects the setting of the electrically controlled valve. In a preferred embodiment, the electrically controlled valve is placed in series fuel flow with one of the manually adjustable valves commonly found on cooking grills.

Abstract: A water heater control system that prevents the accumulation and accidental ignition of dangerous quantities of unwanted flammable vapors. The system intermittently generates a spark at a predetermined interval such that if unwanted flammable vapors are present, they are burned in a controlled manner. The system obviates the need for flammable vapor sensors.

Abstract: The present invention is directed at methods and apparatus for controlling multi-source heating systems. The multi-source heating systems of the present invention may include two or more heat sources such as a heat pump, a furnace, an electric heating strip, or any other suitable heat source. An illustrative system includes a multi-zone, multi-source heating system. The illustrative system may determine which of the multiple sources to use depending on a number of factors. Some illustrative factors include information about zones calling for heat, external environment information, and information about the heat sources. One of the heat sources may be, for example, a heat pump, and a determination of whether to activate the heat pump may include determining the current heating capacity of the heat pump and comparing the heating capacity to the amount of heat needed to satisfy the current heat calls. Methods for determining which of at least two heat sources to use are also provided.

Abstract: A deep format filter element has a peripheral frame with outwardly protruding mounting flanges. The mounting flanges simulate the periphery of a shallow format filter element to allow the deep format filter element to replace the shallow format filter element in many situations. The frame design allows the entire frame to be formed of cardboard and still provide adequate rigidity and strength. The frame includes first and second cardboard sheets forming individual sides of the frame and panels of the mounting flange. The first cardboard sheet includes for each mounting flange at least three folds defining edges of the mounting flange's first end panel and first and second side panels. The second cardboard sheet forms the second end panel of the mounting flange.