The Boeing Company

Jeffrey A Krinsky

Tim R Majoch

Raymond Doak Rempt

Robert A Falk

Disclosed is an electrical control circuit (10) for controlling current through a plurality of resistive loads (14(1), 14(2) . . . 14(N)). The control circuit includes a plurality of current control stages (12(1), 12(2), . . . 12(N)), a comparator circuit (18), and a plurality of diodes D.sub.1, D.sub.2. . . D.sub.N-1 in serial connection with the current control stages. The comparator circuit controls the current that is drawn collectively through the loads. The diodes ensure that all preceding current control stages in the series are conducting a predetermined level of current before the next current control stage begins to source current through its respective load. Each current control stage includes an operational amplifier (30), a pass transistor (34), a sense resistor (R.sub.s), and a feedback resistor (R.sub.f). The operational amplifiers are a pre-drive to the pass transistors to allow smaller sense resistors to be used, thereby providing greater efficiency. The feedback resistors (R.sub.f) provide feedback to the operational amplifiers.

Apparatus for controlling current through a plurality of resistive loads

Disclosed is an electrical control circuit (10) for controlling current through a furnace coil or other resistive load (14). The control circuit includes a plurality of current control stages (12(1), 12(2), . . . 12(N)), a minimum circuit (16), and a control system (22) which provides feedback from the load. The control circuit utilizes a signal conditioner (20) and a sensor (18) to provide information regarding the load to the minimum circuit. The minimum circuit provides the minimum of inputs from the control system and a limit circuit (24) to the current control stages, thereby controlling the current that is drawn through the load. Each current control stage includes an operational amplifier (30), a pass transistor (34), a sense resistor (R.sub.s), and a feedback resistor (R.sub.f). The sense resistors ensure that there is current sharing through each of the current control stages. The operational amplifiers are a pre-drive to the pass transistors to allow smaller sense resistors to be used. The feedback resistors (R.sub.f) provide degenerative feedback to the operational amplifiers.

Apparatus for limiting current through a plurality of parallel

An optical repeater that amplifies and reshapes an input pulse without converting the pulse into the electrical domain. The repeater comprises an optical gain device, a mode selector, and an optical thresholding material. The optical gain device comprises an optical gain material with anti-reflection coatings at its input and output ports. The mode selector receives an optical signal amplified by the gain medium, and preferentially transmits one or more preselected spatial modes to the thresholding material, which shapes the pulses for retransmission.

Radiation-hardened optical repeater

An optical receiver particularly suited for use in a noisy environment, the receiver includes an optical gain device for amplifying an input signal to produce an amplified input signal, a photodetector, and a mode selector. The optical gain device includes an optical gain medium, an optical input port through which the input signal may be received into the optical gain medium, and an optical output port through which an optical output signal may leave the optical gain medium. The output signal includes the amplified input signal, plus any noise generated within the optical gain device. The input and output ports include antireflection means. In a preferred embodiment, the mode selector comprises a single mode fiber-optic cable that transmits a single spatial mode of the output signal to the photodetector.

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Renton, WA, United States of America

Jeffrey A Krinsky