Abstract: A shoot-through protection circuit includes a current sensor providing a sensor signal connected to a comparator input via at least a burden resistor. A switch protection circuit including a protection input connected to an output of the comparator and a plurality of outputs. Each of the outputs is connected to a corresponding switch in a plurality of stacked switches. Wherein the switch protection circuit is configured to drive each switch of the plurality of stacked switches open in response to a positive output signal from the comparator.

Abstract: A backplane apparatus for an electronic device enclosure includes a common bus comprising a plurality of signal lines, each signal line having a current limiting element, RA. Isolation circuitry is provided for electrically coupling each of the plurality of signal lines of the common bus to a corresponding plurality of signal lines of the electronic device to enable signal communication between the common bus and the electronic device through the isolation circuitry. In one embodiment, the backplane apparatus further comprises connectors to enable removably attaching the electronic devices such as disk drives. In one embodiment, the isolation circuitry coupling each signal line of the common bus to the connector comprises an inline resistor, RD. The isolation circuitry associated with some of the signal lines may include pull up resistors.

Abstract: A backplane apparatus for an electronic device enclosure includes a common bus comprising a plurality of signal lines, each signal line having a current limiting element, RA. Isolation circuitry is provided for electrically coupling each of the plurality of signal lines of the common bus to a corresponding plurality of signal lines of the electronic device to enable signal communication between the common bus and the electronic device through the isolation circuitry. In one embodiment, the backplane apparatus further comprises connectors to enable removably attaching the electronic devices such as disk drives. In one embodiment, the isolation circuitry coupling each signal line of the common bus to the connector comprises an inline resistor, RD. The isolation circuitry associated with some of the signal lines may include pull up resistors.

Abstract: Fan brakes for decelerating blower impellers particularly for modular equipment enclosures are described. A module includes a blower having an impeller with a plurality of blades. The brake engages the impeller body or blades when the module is at least partially removed from the enclosure and disengages the impeller when the module is inserted into the enclosure. One brake includes an arm coupled to a braking surface. The arm applies the braking surface to the impeller when disengaged by a cam and retracts the braking surface from the impeller when engaged by the cam. A solenoid may be used in lieu of a cam for directly or indirectly applying the braking surface.

Abstract: A circuit board including differential bus traces on or buried within both sides of the board, interconnecting electronic devices such as disk drives, processors, and connectors for external cables. Via fields, which mimic the size and configuration of the device and cable connector fields, are located between each connector on the board. The via fields link bus traces on or within one side of the board with respective bus traces on or within the other side of the board. The via fields may include subtle, unequal undulations in the trace patterns to provide equalization in the lengths of all trace pairs. The via fields and the connector fields both include repetitive conductor order reversals in the trace connections on opposing sides of the board, to reduce crosstalk between channels. The via fields may be oriented parallel with respect to collinearly arranged devices, or orthogonal with respect to devices or connectors which are parallel.

Abstract: A power distribution unit adapted for mounting within an electronic system. The power distribution unit includes at least one mounting hinge that is fixedly attached to the power distribution unit housing and which is adapted to fixedly mount the power distribution unit to an enclosure of the electronic system or to an internal support or component within the electronic equipment enclosure. The mounting hinge is pivotable such that the power distribution unit can be pivoted to an extended position to facilitate removal of removable modules mounted within the electronic system.

Abstract: A power distribution unit adapted for mounting within an equipment enclosure including an inner rack. The power distribution unit includes at least one mounting hinge that is fixedly attached to the power distribution unit housing and which is adapted to fixedly mount the power distribution unit to the rack columns. The mounting hinge is pivotable such that the power distribution unit can be pivoted to an extended position to facilitate removal of removable modules of the equipment components mounted within the equipment enclosure.

Abstract: A liquid level sensing apparatus, and related method, that utilizes a tuning fork assembly to detect the presence of not only a liquid or air at a particular location within a container, but also a solid material at that location. The tuning fork assembly includes an excitation transducer and a receiving transducer mechanically coupled to a pair of paddles that are exposed within the container, and a phase-locked loop control system applies an excitation signal to the excitation transducer having a frequency that is regulated to track the tuning fork's resonant frequency. A comparator compares that resonant frequency with a prescribed threshold, to determine whether the tuning fork assembly is disposed in air or a liquid. A failure of the phase-locked loop control system to lock the frequency of the excitation signal at any particular frequency indicates that the tuning fork assembly is over-damped and likely contacted by a solid material.

Abstract: A time-domain reflectometer is disclosed for reliably measuring the level of a liquid in a tank. The reflectometer emits an acoustic signal into a waveguide that projects downwardly into the tank and receives a return acoustic signal reflected from the surface of the liquid. The time delay between the transmitted acoustic signal and the reflected acoustic signal is a measure of the level of the liquid, and the reflectometer converts this level measurement into a electrical current that is linearly proportioned between predetermined minimum and maximum values. In addition, the reflectometer incorporates a liquid- and vapor-impervious membrane disposed in the path of the transmitted and reflected acoustic signals, adjacent to the transmitter and receiver, to prevent the escape of liquid and vapor from the tank and to isolate the electronics, including the transmitter and receiver, from such liquid and vapor.

Abstract: A highly manufacturable low cost DC-to-DC power converter uses a control circuit constructed from a '555 type timer IC and a precision voltage reference. The output of the '555 timer is used to drive a MOSFET transistor that alternately energizes and de-energizes a primary winding of a transformer, thereby energizing secondary windings of the transformer. The voltage at the secondary windings is rectified and filtered to form the regulated output supply voltages. A feedback control signal is generated based on a difference between a reference voltage and the a regulated output supply voltage. Based on the feedback control signal, a control window is established within the '555 timer that determines the charging and discharging times of a capacitor. Since the charging and discharging times of the capacitor are exponential, changing the feedback control signal changes the control window, which in turn changes the charging time with respect to the discharging time.

Abstract: A magnetic shield is designed to be retrofitted over a flyback transformer of a cathode ray tube display terminal. The magnetic shield consists of a layer of metal conductor, for example mu metal, and a layer of insulation, for example polyester film. The layer of insulation is placed upon the layer of metal conductor and the layers are rolled to form a spiral having greater than two windings. Tape may be used to secure the shape of the spiral. Additionally foam rubber pads may be attached to the inside of the spiral to provide a secure mechanical mounting to the flyback transformer and to provide air spacing as additional insulation against corona discharge. Also shrink tubing may be placed over the spiral to provide additional support to the spiral shape and to provide heat and electrical insulation.

Abstract: A signal generator which generates an amplified yoke signal for application to a vertical yoke of a cathode ray tube monitor is presented. The signal generator includes a linear ramp generator and a correction generator. The linear ramp generator has an output on which is placed a ramp signal. The linear ramp generator also has a first input which receives a clock signal. The frequency of oscillation of the clock signal determines the frequency of oscillation of the ramp signal. The linear ramp generator additionally has a second input for receiving a height adjustment signal. The linear ramp generator varies the maximum voltage range of the ramp signal responsive to the height adjustment signal. The maximum voltage range is varied independent of the frequency of oscillation of the ramp signal. The correction generator receives the ramp signal from the linear ramp generator and generates an "S" correction signal.