Abstract: A two chamber heat transfer unit configured such that hazardous air can circulate through one of the chambers of the heat transfer unit and any potential ignition source components are contained in another pressurized chamber of the heat transfer unit.

Abstract: Assuring acquisition of symbol timing in a full-duplex data transceiver under inter-symbol interference conditions. One embodiment includes a transmitter comprising a first local clock having a first free running frequency, and a receiver comprising a second local clock having a second frequency initially set to a value higher than the first free running frequency. A first type decision-directed timing recovery mechanism is intentionally limited to only decreasing the frequency of the second local clock. A second type decision-directed timing recovery mechanism is not limited to only decreasing the frequency. The receiver receives symbols, decrease the frequency of the second local clock to a third frequency value using the first type decision-directed timing recovery mechanism, disables the first type mechanism after reaching the third frequency, and then phase-lock the second local clock to the optimal phase under MMSE criteria using the second type decision-directed timing recovery mechanism.

Abstract: An authentication device or other type of low-power hand-held device comprises a processor, an external button alternately configurable in an unpressed state and a pressed state, and current drain mitigation circuitry coupled to the external button and a corresponding input of the processor. The current drain mitigation circuitry is configured to connect the input of the processor to a first potential when the external button is in the unpressed state and to connect the input of the processor to a second potential different than the first potential when the external button is in the pressed state, thereby limiting current drain arising from the external button being stuck in the pressed state.

Abstract: The invention relates to a method and a circuit arrangement for monitoring the mode of operation of one or more load circuits, especially of a domestic appliance, which contains a controlled semiconductor switch, such as a triac, and an electric consumer. Said switches are supplied by at least one alternating voltage source that supplies an alternating voltage including positive and negative voltage half-waves. The invention is characterized in that the currents flowing through all controlled semiconductor switches (T1, T2) and the electric consumers (R1, R2) are guided through a common low-impedance precision resistor (Rm). The respective voltage drop occurring over the low-impedance precision resistor (Rm) is separately evaluated with respect to the amplitudes of the positive and negative voltage half-waves.

Abstract: An electronic control, with a floating ac power supply, that compares the digital signals produced by connections between ac circuit nodes and digital nodes to determine whether path(s) in ac circuits containing the ac nodes are intact or open. The connections are made through passive components which limit the current between nodes to levels the digital devices can safely handle. An open path indicates to the control that a switching device is open, a connection has failed, or a that a load component has failed or is missing. An intact path indicates a closed switch or a present and presumably functional load component. Proper connections enable the control to detect the state of multiple paths while still being able to detect zero crossings. The method can determine the state of ac paths even if hot and neutral connections are inadvertently reversed.

Abstract: An SCR firing circuit is provided which includes a plurality of opto-couplers, diodes, a capacitor and an SCR, utilized to control the AC power applied to a load, such as a vibratory feeder. In various embodiments of the invention, one or more opto-couplers act as solid state switches and also isolate a control signal from the AC line voltage. The capacitor is charged from an AC power source through the diode during a half cycle of the AC line voltage, and remains charged until the SCR is triggered. In response to a control signal rendering the opto-couplers conductive, the capacitor is discharged through the opto-couplers to fire the SCR and provide AC power to the load. A back-to-back SCR firing circuit is also provided which fires a first SCR when a line voltage is positive and which fires a second SCR when the line voltage is negative, which may be utilized to adjust the frequency of the application of power to the load independently of the frequency of the AC power supply.