Abstract: A pitch drive circuit that operates in an emergency mode, for a wind or water power plant. The circuit has at least one rectifier unit, at least one DC intermediate circuit, two inverter units and a pitch rotary current motor with motor trains that can be contacted on both sides. A first contact side of the motor trains is connected to a first inverter unit and a second contact side of the motor trains is connected to a second inverter unit. At least one switching element is connected to at least one contact side of the motor trains. In a normal operating mode of a first switching state of the switching element the motor trains can be energized via both inverter units, and in an emergency operating mode of a second switching state of the switching element, the motor trains can be energized via a single inverter unit.

Abstract: The invention relates to a pitch drive circuit (50, 52, 54), which can operate in emergency mode, for a wind or water power plant (80), said circuit comprising at least one rectifier unit (14), at least one DC intermediate circuit (18), two inverter units (16-1, 16-2) and a pitch rotary current motor (38) with motor trains (30) which can be contacted on both sides. A first contact side (76-1) of the motor trains (30) is connected to a first inverter unit (16-1) and a second contact side (76-2) of the motor trains (30) is connected to a second inverter unit (16-2). At least one switching element (40) is connected to at least one contact side (76) of the motor trains (30).

Abstract: One embodiment of the present invention is directed to a read head for a data storage device including a sensor for reading data from a data storage medium, a first shield disposed adjacent to the sensor and characterized as moment-compensated, and a second shield disposed adjacent to the sensor, the second shield being moment-compensated.

Abstract: A ground fault interrupt circuit with an improved current window detector. The current window detector works by first rectifying the input current in a pair of current mirrors connected in back to back fashion in the feedback path of the input amplifier. The rectified current triggers an output when the rectified current exceeds a predetermined threshold.

Abstract: An integrated circuit comprising a plurality of gain cells interspersed with a plurality of passive and active, electrically isolated components (e.g. thin-film binarily-weighted resistors and transistors). Each gain cell comprises a differential amplifier gain stage comprising a pair of emitter-coupled transistors, the coupled emitters being connected to a current source. The collectors thereof are coupled to a pair of transistors configured as a current mirror. The emitter-coupled transistors, current source and current-mirror transistors are disposed on a first level of the integrated circuit. A first output stage comprising a common-emitter transistor and a second output stage comprising a transistor having an electrically isolated emitter are disposed on the first level.

Abstract: An electronic circuit is provided comprising: a pair of transistors having collector electrodes connected together at an output terminal and emitter electrodes coupled to opposite potentials of a voltage supply; a current source; and, means, responsive to a current produced by the current source, for establishing bias currents to base electrodes of the pair of transistors in accordance with an input signal, such bias currents being dependent on the current produced by the current source and being substantially independent of, over a nominal operating supply voltage range of the circuit, of variations in the voltage supply. With such arrangement, since the bias current to the transistors are provided from a current source, the bias currents are independent of the voltage supply and the circuit may operate with less than a one volt voltage supply. In accordance with a preferred embodiment of the invention, a resistor is coupled between the voltage supply and an emitter of one of the pair of transistors.

Abstract: A transistor switching circuit is provided for providing an indication of when the level of an input signal has passed through a first threshold level, such indication continuing unless such input signal has returned beyond the first threshold level to a second threshold level. Such circuit is useful in indicating whether the battery of a battery powered device should be replaced taking into consideration small variations in the output of the battery after the initial replacement indication has been provided.

Abstract: A current source circuit includes a current mirror circuit having a master transistor and at least one slave transistor. The master transistor is coupled to a differential amplifier. The differential amplifier includes a pair of transistors, one thereof being coupled to a reference current source and the master transistor and the other one having a collector electrode connected to the base electrodes of the master and slave transistors for producing a current through the collector electrode substantially equal to the total current flow through the base electrodes of the master and slave transistors.