Abstract: Here is disclosed a push-pull inverter used to drive a cold cathode discharge tube, a hot cathode discharge tube and the like, comprising a boosting transformer having a first primary coil, a first secondary coil, a second primary coil and a second secondary coil; first and second switching elements each having a control electrode adapted for controllably interrupting primary current flowing through said first and second primary coils; a capacitor connected between the respective control electrodes of the respective switching elements; and a feedback circuit in which one end of the first secondary coil is connected to the control electrode of the first switching element and one end of the second secondary coil is connected to the control electrode of the second switching element so that load current from a load connected between the other ends of the respective first and second secondary coils flows through the capacitor.

Abstract: An H-bridge circuit which includes four power transistors (an npn pull-down and a pnp pull-up for each of the output terminals). Two control circuits are connected to drive these transistors in a complementary crossover configuration, so that each control circuit can turn on the pull-up transistor on one side of the load and the pull-down transistor on the opposite side of the load. Each of the power transistors is paralleled (base-to-base) by a smaller transistor which provides a scaled current output (proportional to that of the corresponding power transistor) to the opposite control circuit. The control circuit includes static current-thresholding disable logic, which prevents turn-on until the currents through the opposite power devices have declined to threshold levels. Thus, as long as either control circuit is driving one of the pull-up transistors into in the on-state, the other control circuit will not be able to turn on the pull-down transistor which is in series with the active pull-up transistor.

Abstract: A power-supply unit having a rectifier circuit, switch, first and second voltage generation circuits, a control circuit, and a capacitor. The rectifier circuit is connected to an A.C. power source. The switch opens/closes an electric line which supplies a load circuit with electric power from the A.C. power source via the rectifier circuit. The first voltage generation circuit generates a first voltage based on an output voltage of the rectifier circuit. The first voltage is a non-zero voltage. The second voltage generation circuit generates a second voltage based on the output voltage, and is larger than the first voltage. The control circuit turns the switch on when the output voltage is in a range between the first voltage and the second voltage, and turns the switch off when the output voltage is outside the range.

Abstract: The invention relates to a switching power supply having a protection device to shutdown the supply of the output voltage and a circuit for providing a trickle voltage while the power supply is shutdown. The power supply is shutdown by lowering the primary bias voltage, the voltage which powers the internal components of the power supply, to a value which disables the production of the output voltage. However, the primary bias voltage is not reduced to ground. Various circuits and devices, such as a restart circuit, may then be powered by the trickle voltage while the power supply is shutdown.

Abstract: Control circuits for a switching voltage regulator circuit which uses magnetic flux sensing are provided. These circuits can be used to improve output voltage regulation by reducing parasitic effects inherently present in magnetic flux-sensed feedback switching voltage regulator designs.

Abstract: An electromagnetic bearing including a stator portion having sixteen magnetic cores facing the rotor portion. The sixteen cores are divided into four groups of four cores, and each group is equipped with suspension electric windings disposed such that the magnetic flux produced thereby is in the same direction in the first two cores of the group and in the opposite direction in the following two cores, each core in each group further being equipped with a position-detection electric coil, the coils on the four cores in any one group being connected together in series and powered by an AC electric current, the magnetic flux produced by the coils at any determined time being in opposite directions in the first two cores of any group, and also in opposite directions in the following two cores.

Abstract: A direct current to direct current converter utilizes a MOSFET half-bridge configuration in which the inherent magnetizing and leakage inductances of the transformer are used as the only inductances in the frequency-determining circuit. Diodes are used to limit the voltages across the capacitor of the frequency determining circuit and hence limit the short circuit and open circuit characteristics of the converter. A self-starting circuit insures that the circuit will start up when initially energized.

Abstract: A CMOS on chip mid-rail voltage generation circuit is provided for an analog ground reference. A voltage divider establishes a current path between the high and low rail, and supplies a mid-level voltage to one input of a differential amplifier. A pair of series connected field effect transistors are also connected between the high and low voltage rails, with their common connection providing the input to the other input of the differential amplifier. A pair of open loop output transistors are also coupled in series between the high and low voltage rails, and each has their gate coupled to one of the series connected pair, and is also matched to that pair.

Abstract: This overload protection circuit capable of sustaining high capacitive load or any other load which may create an important inrush current, comprises a differential bridge composed of high impedance measuring resistors (R1, R1' R3, R3'), a low impedance sensing resistor (R2), and a timing and control circuit (20) including a transistor (T2), a capacitor (C1) and resistors that controls a switch (T1) and limits the inrush current of the subcircuit capacitor by slowing the closing of the switch. In case of defaults, the switch will be opened fast enough to minimize the fault transient transfer from down-stream to up-stream of the protection circuit. In addition, a comparator (32) associated to a resistor (R31) providing an hysteresis enables to avoid the oscillations in the region of the system transition from on to off states and vice versa. This circuit can be used in a system which comprises a secondary power supply unit (9) which powers a plurality of subcircuits (22).

Abstract: The invention relates to a bi-polar power supply for a plasma chamber including an adjustable DC power supply having a positive output terminal and a negative output terminal. A transistor bridge circuit having two input bridge terminals is coupled to the positive and negative output terminals. Two bridge output terminals of the transistor bridge are coupled to the plasma chamber. A current detector is coupled to the two bridge output terminals for detecting the current flowing to the plasma chamber and controlling the transistor bridge circuit to provide a bi-polar power supply to the plasma chamber.

Abstract: The invention relates to a semiconductor switch control circuit comprising a timing logic unit (1), a first and a second driver (2, 3) controlled by the timing logic unit, a first and a second transformer (T1, T2), to which the first and the second driver (2, 3), respectively, apply an unmodulated ac voltage signal (A, B) for bringing the semiconductor switch into a conducting and non-conducting state, respectively, and the secondary windings of which are connected at the opposite ends to a reference potential (RP); a first and a second rectifier (4, 5) for rectifying dc voltages (V+, V-) of opposite polarity from a voltage (A, B) acting across the secondary windings of the transformers; a first and a second driver (10, 11) for maintaining the semiconductor switch (12) in a conducting and non-conducting state, respectively; and capacitor units (8, 9) for storing the turn-on and turn-off energy of the semiconductor switch, respectively.

Abstract: A high power factor AC/DC converter is disclosed. In the AC/DC converter in which a rectifying circuit RC1 rectifies a commercially available AC power supply Ei, a switching device turns on and off so that the rectified voltage is applied across the primary winding n1 of the transformer Tr1 to provide a high frequency voltage across the secondary winding n2, and the high frequency voltage is rectified by means of a rectifying circuit connected across the secondary winding so as to generate a predetermined DC output, a choke coil (L1) and a diode (D1) are interposed between the rectifying circuit (RC1) and a smoothing capacitor (C1) and a capacitor (C3) is interposed between a first junction and a second junction. The first junction connects the choke coil (L1) to the diode (D1) and the second junction connected the switching device (Q1) to the primary winding (n1) of the transformer (Tr1).

Abstract: In a zero-current switching forward converter both a unidirectional conducting device and a circuit consisting of a switch in series with a dissipative element are connected across the energy transfer capacitor in the output circuit of the converter. The switch is turned off at the beginning of an energy transfer cycle and is turned on when the voltage across the energy transfer capacitor returns to zero. At relatively high values of load, current flowing in the converter output inductor in the direction of the load will be bypassed around the energy transfer capacitor by the unidirectional conducting device and converter operation will be the same as a prior art zero-current switching forward converter.

Abstract: First, second, and third power supply lines are separate from each other. A power supply circuit receives electric power from the first power supply line, and generates a given power supply voltage from the received electric power and outputs the generated power supply voltage to the third power supply line. An electronic circuit is connected to the third power supply line to be activated by the power supply voltage. The electronic circuit has an input section for receiving an input signal from the second power supply line. A protective circuit provided in the electronic circuit leaks a current from the input section of the electronic circuit toward the third power supply line when a voltage of the input signal exceeds the power supply voltage.

Abstract: A television receiver has a switched mode power supply for regulating an output voltage, including a power transformer having a primary winding coupled to an unregulated voltage via a power transistor. The power transistor is controlled by pulses from the output of a controller. In order to sweep the base-emitter charge from the power transistor in order to end collector-emitter conduction, the base of the power transistor is coupled to the output of the pulse generating controller via a capacitor in parallel with at least one diode. During a pulse from the controller, the capacitor is charged to a voltage equal to the forward biased drop across the diode(s). At the end of a pulse at the output of the controller, the voltage across the capacitor provides a negative voltage at the base of the transistor, thus sweeping out the base-emitter charge and sharply turning the transistor off.

Abstract: The performance of AC to DC and DC to DC boost preregulators, and the performance of the equipment of which they form a part, can be improved by means of an adaptive boost switching preregulator which can, when used with a load capable of operating over a range of load voltages, increase or optimize the conversion efficiency and reliability of both the preregulator and the load by adaptively controlling the load voltage as a function of the voltage of the input source. Also, a gain-variable current controller can be provided which allows for accurately controlling the waveform and magnitude of the input current of a switching preregulator as the preregulator load (and hence the input current) varies over a wide dynamic range, yet does so by comparing signals whose magnitudes are essentially independent of the magnitude of the load. In this way, second order effects, which cause degradation in control of power factor in other preregulators as load is decreased, are rendered less significant.

Abstract: A high density electronic module packaging system includes a cabinet for housing a plurality of modules. Disposed at the rear of the cabinet and forming a rear wall thereof is a cooling system housing that is used for cooling the modules contained in the cabinet Disposed within the cabinet are a plurality, e.g., four, cooling modules; a power distribution unit having a plurality, e.g., twelve, power converters; and a plurality, e.g., twenty-eight electronic modules. The number of cooling modules, power converters and electronic modules may be added or subtracted as needed or desired. The cooling modules flow cooling fluid to and/or from the power distribution unit and/or to the plurality of electronic modules. The power distribution unit supplies power to the plurality of electronic modules. The electronic modules may house one or more submodules such as storage devices (e.g., disk drives) or printed circuit boards.

Abstract: A DC to DC power converter in the form of a pulse-width modulator is shown which can sense via an indication of duty cycle how much reserve power is available for loads using the present input voltage. The device is for use at the end of a telephone line where the input voltage power supply impedance can be appreciable. When the reserve power, as detected in the power converter, reaches a minimum critical level, a signal is sent out requesting the voltage supply to increase the available voltage to the power converter.

Abstract: Equipment for the generation of a stabilized high direct voltage is described, and includes: a step-up transformer (2) whose primary is supplied with a direct voltage and which is designed in such a way as to have dispersed inductances and parasitic capacitances which cause a resonance effect on the opening of the primary; a rectifying circuit (3) to rectify the voltage at the terminals of the secondary winding of the step-up transformer (2); a switch (11) which, when in the closed condition, connects the primary winding of the step-up transformer (2) to ground; and circuits (6,7,8,9) for controlling the opening and closing of the switch (11).

Abstract: A system for providing a constant current to airport or airfield signs is disclosed. The system receives input currents of varying amperages which also supply, and allow dimming of, runway or taxiway lights. According to various exemplary embodiments of the present invention, a high power factor is achieved which provides greater cost efficient operation of the signs.