Abstract: In making constant a direct-current output voltage obtained by rectifying an alternating voltage generated in a secondary winding of an isolating converter transformer PIT, an active clamp circuit formed with an auxiliary switching device, a clamp capacitor, and a clamp diode is connected in parallel with a parallel resonant capacitor to be supplied with the alternating voltage, instead of using a three-terminal regulator and a chopper regulator, which step down and make constant the direct-current output voltage. A control circuit effects PWM control of the auxiliary switching device of the active clamp circuit and thereby equivalently changes capacitance of the parallel resonant capacitor. Thus, the direct-current output voltage is made constant, and power loss caused in making the direct-current output voltage constant is reduced.

Abstract: A method and system for increasing the output of an alternator for an automotive vehicle has a first three-phase winding (18) and a second three-phase winding (20) that are coupled to a respective first rectifier circuit (26) and a second rectifier circuit (28). A switch circuit (30) is located between the first rectifier circuit (26) and the second rectifier circuit (28). A controller (32) that is coupled to a speed sensor (34) and provides a signal indicative of the speed of the alternator, controls the operation of the switch circuit (30). When the speed sensor (34) indicates that the speed of the alternator is below a predetermined threshold, the first rectifier circuit (26) and second rectifier circuit (28) are coupled together through switch circuit (30). When the speed sensor (34) indicates that the speed of the alternator is above a predetermined speed, the switch circuit (32) is controlled to an open state so that two parallel half-wave rectifier circuits are formed.

Abstract: A rectifier comprising a current transformer configured to receive a bipolar signal. The current transformer is comprised of a primary coil and preferably two secondary coils with opposite polarities. The rectifier also includes a rectifying transistor coupled to one of the secondary coils in the current transformer. Positive current from the first secondary coil causes the transistor to turn on thereby allowing current to flow through the transistor from the input of the rectifier to the output of the rectifier. A pull-down transistor is coupled to a second secondary coil of the current transformer. Positive current from the second secondary coil causes the pull-down transistor to turn on. The pull-down transistor is configured to connect the control terminal of the rectifying transistor to ground, thereby turning the rectifying transistor off, when the pull-down transistor is turned on.

Abstract: The present invention is related to a flyback converter with synchronous rectifier, and to use the current sensor coupled with the synchronous rectifier to detect the secondary current of the transformer. Using the secondary current, this invention could control the pulse width of the output signal from the synchronous rectifier to make the diode turn on in the same time with the synchronous switch. This invention could improve the power efficiency of the power supply and avoid the secondary current flows back, and simplify the circuit design to make the production much easier to cost down.

Abstract: There are provided: a main three-phase full-wave rectifier (8) that converts three-phase AC (R phase, S phase, T phase) into DC; a transformer (9) that outputs AC of a total of six phases corresponding to the points that equally divide by three the arcs drawn in a transformer vector diagram in which an equilateral triangle is formed whereof the R phase, S phase and T phase are vertices, centered on each vertex and linking the remaining two points; and two auxiliary three-phase full-wave rectifiers (12) and (13) that convert into DC the six-phase AC that is output from the transformer (9), the output lines of the main three-phase full-wave rectifier (8) and two auxiliary three-phase full-wave rectifiers (12) and (13) being connected in parallel. The current flowing in the DC line through the transformer can therefore be reduced to ⅓ of the whole in the case of an 18-pulse rectifier, so enabling the capacity of the transformer to be reduced.

Abstract: Embodiments of the present invention are directed to an uninterruptible power supply for providing AC power to a load. In embodiments of the present invention, the uninterruptible power supply includes an input to receive AC power from an AC power source, an output that provides AC power, a DC voltage source that provides DC power, the DC voltage source having an energy storage device, an inverter operatively coupled to the DC voltage source to receive DC power and to provide AC power.

Abstract: Briefly, in accordance with one embodiment of the invention, a power brick for use with a network adapter includes: a power supply and at least one signal transformer. The power supply and the signal transformer are physically remote from the network adapter and capable of being electronically coupled to the network adapter via a cable. Briefly, in accordance with another embodiment of the invention, a power brick for use with a network adapter includes: at least two signal transformers. The at least two signal transformers are physically remote from the network adapter and capable of being electronically coupled to the network adapter via a cable. Briefly, in accordance with on more embodiment of the invention, a method of using a power brick with a network adapter includes the following. A high voltage power supply including superpositioned high frequency communications signals is received via a power brick. The voltage of the received signal is reduced.

Abstract: The present invention relates to a DC transformer/reactor comprising a magnetic circuit, wherein the magnetic circuit comprises a magnetic core and at least one winding. The winding comprises at least one current-carrying conductor. Each winding comprises also an insulation system, which comprises on the one hand at least two semiconducting layers, wherein each layer constitutes substantially an equipotential surface, and on the other hand between them is arranged a solid insulation.

Abstract: Briefly, in accordance with one embodiment of the invention, a power brick for use with a network adapter includes: a power supply and at least one signal transformer. The power supply and the signal transformer are physically remote from the network adapter and capable of being electronically coupled to the network adapter via a cable.

Abstract: A zero voltage switching synchronous rectification circuit for providing multiple output voltages from a single input voltage is disclosed. The circuit comprises a single transformer coupled to the single input voltage and at least two synchronous rectifiers, each of the at least two synchronous rectifiers being coupled to the transformer via a winding, each of the at least two synchronous rectifiers including a first controlled switching device coupled to the winding, wherein at least one of the at least two synchronous rectifiers includes a delay element, the delay element being coupled to the winding via the first controlled switching device, wherein the delay element delays the input voltage across the at least one of the at least two synchronous rectifiers for a predetermined amount of time. By incorporating a delay element with a plurality of isolated synchronous rectifiers, Zero Voltage Switching is achieved in a multiple output environment.

Abstract: A self-regulated synchronous rectifier is connected between a secondary transformer winding and an LC filter. The rectifier includes two MOSFETs each having a gate connected in series with a gate protection circuit. Each gate protection circuit includes a divider bridge and a switch connected in parallel with the divider bridge and having an open position and a closed position and the rectifier includes a control device for controlling the switches which receives an input signal proportional to the input voltage of the rectifier and produces output signals for controlling the switches.

Abstract: A multiple-power supply traction system capable of operating under a single-phase AC power supply and under a DC power supply, wherein a common set of capacitors is used when operating under either kind of power supply. The present invention also relates to a method of implementing such a multiple-power supply traction system.

Abstract: A device and associated method for limiting a current surge in a capacitor connected to the output of a rectifying bridge having its input connected to an a.c. voltage, the bridge being a composite bridge and being associated with means for synchronizing the turning-on of the bridge from zero crossings of the voltage of the a.c. power supply.

Abstract: A power factor correction circuit using a first rectifier diode to control the series charging of two capacitors and two rectifier diodes to control the parallel discharging of the two capacitors. The power factor correction circuit further includes a resistor that is series-connected with the first diode to improve the power factor and to reduce the current drawn when the voltage is turned on. The rectifier diodes are advantageously voltage limiting diodes to protect the downline circuitry against overvoltages. In one improvement, a current-controlled electronic switch is used for protection against overvoltages that are just above the peak value of the line voltage.

Abstract: An integrated circuit servo system demodulator that incorporates a high speed gain stage with DC offset cancellation. The gain stage receives a differential voltage signal representing a servo burst and converts the differential voltage signal to a differential current signal by a transconductance amplifier. The differential current signal is full-wave current rectified and converted to a full-wave rectified voltage signal by a transimpedance amplifier. A DC offset cancellation circuit is coupled between the full-wave current rectifier and transimpedance amplifier and functions to mirror and subtract, from the rectified current signal directed to the transimpedance amplifier, any DC leakage current developed by the rectifier which would generate a DC offset voltage through the transimpedance amplifier.

Abstract: A converter powered by an alternating network drawing therefrom a current with a power factor close to unity and a non-linear distortion factor close to five percent, wherein the amplitude of the current applied to an output load remains substantially constant. A bridge circuit is provided using switches and capacitors wherein the reactance at the quench frequency is selected such that a portion of the converted energy is added between the terminals of an output capacitor to the main current rectified by a bridge. A buffer source has a direct voltage with substantially constant amplitude which enables balancing of the generated voltages, thereby eliminating the risk of destruction by uncontrollable excess voltages.

Abstract: An automatic power control device has a charge battery, a voltage level circuit, a power circuit, and a first and a second photo control circuit. The voltage level circuit has an indication lamp, a switch connected with the indication lamp in parallel, two resistors respectively connected to an end of the switch, and two neon lamps connected to the two resistors, so as to turn on one or two neon lamps by turning the switch off or on thereby generating light. The first and second photo control circuits are provided for detecting the light from the neon lamps to activate the power circuit for selectively supplying power to a load and the charge battery. Each photo control circuit has a photo resistor for detecting the light. The first photo control circuit has a first relay to control the power supply of the power circuit. The second photo control circuit has a second relay for determining whether the power circuit or the charge battery supplies power.

Abstract: In a switching power circuit adopting the synchronous rectifying system, when a first switch is cut-off, current I.sub.L of an inducing element is maintained by a commutating diode, and the inducing element releases an energy which was stored in a conduction period of the first switch. A second switch connected in parallel to the commutating diode is conducted so as not to be overlapped with the conduction period of the first switch. In the conduction period of the second switch, the current I.sub.L does not flow through the commutating diode, and it is possible to prevent lowering of efficiency caused by forward voltage drop. An inducing element current detecting circuit monitors the current I.sub.L and, when the current I.sub.L is reversing its direction, instructs a control circuit to cut-off the second switch. As a result, no reverse current flows through the inducing element even when the load is small, thus realizing a switching power circuit always having high efficiency.

Abstract: A compact, low-cost outage management emergency power supply device with a simple constitution is provided by connecting an auxiliary capacitor and charging battery to a DC link portion. In one embodiment, an auxiliary capacitor is connected in series via a switching circuit to a DC link portion which supplies direct-current voltage of a converter device which converts alternating-current voltage to direct-current voltage, and the input-output of current to the auxiliary capacitor is controlled by the switching circuit, so that the capacity of the additional auxiliary capacitor is not subject to limitations. Further, in another embodiment, a charging battery is connected to a DC link portion via a parallel circuit of a switching circuit or diode, and a resistor.

Abstract: A protected, transformerless power converter for converting an AC mains power source to a low voltage DC power source is presented. The AC input voltage is rectified to supply pulsating DC voltage to a pass element resistor. An electronic switch located between the pass element resistor and an output filter capacitor interrupts the current flowing into the output filter capacitor. The output filter capacitor averages the pulse current drawn from the AC input line to provide a constant DC output voltage to a load. The instantaneous AC input voltage, the average value of the AC input voltage, and the output voltage are used to calculate the optimal times of conduction of the electronic switch. Controlling the time of conduction in this manner maximizes the power efficiency of the converter and protects the supply from an output overload or short circuit condition over a wide range of AC input voltages.

Abstract: A tridirectional inverter is disclosed which converts power from the single source into two different widely types of power outputs. This conversion s done by utilizing a magnetic element, i.e., a transformer, alternatively as a filter and as a voltage changing transformer. The function that the magnetic element provides is accomplished by selecting the frequency of the signal that is applied to the magnetic element.

Abstract: To provide an AC/DC converter including a resonant converter which reliably supplies a constant DC power supply voltage (U.sub.out) in a wide output power range, while using a minimal number of components, and in which the input impedance of the AC/DC converter should have a minimal reactive impedance, both a capacitive (C2) and an inductive (n3) coupling of the resonant converter (8) to a point (5) between the resonant converter (8) and a rectifier arrangement (1) is provided. The rectifier arrangement is used for rectifying an AC voltage (U.sub.in) applied to the AC/DC converter.

Abstract: A digital control in line angle coordinates for a regulated power input device in which the line angle (.epsilon.) is determined from measured line voltages (U1M, U2M) by means of a coordinate transformation of the rotary field, in Cartesian coordinates and subsequent arctan calculation (ATAN). From this, under circumstances of a heavily disturbed line angle (.epsilon.) the line frequency is computed. In this, under circumstances, the strongly varying frequency information is limited to a plausible band of variations before the frequency is filtered and a relatively smooth running line angle (.epsilon.) can be calculated therefrom. In order to avoid an erroneous integration, the calculated line angle integrator is set at every phase-zero-crossing to the corresponding angle value. With this line angle (.epsilon.

Abstract: A soft start circuit for controlling a rectifier circuit, the rectifier circuit for converting power from an AC source having one or more phases to DC power having an output voltage (Vo) from a Vo+ node to a Vo- node, the rectifier circuit including: (i) at least first and second rectifier legs coupled from the Vo- node to the Vo+ node, each rectifier leg including a diode and a silicon controlled rectifier (SCR), wherein anodes of the diodes are coupled to the Vo- node, cathodes of the diodes are coupled to anodes of the SCRs at AC input nodes, and cathodes of the SCRs are coupled to the Vo+ node; and (ii) a bus capacitor coupled from the Vo+ node to the Vo- node, the soft start circuit operable to control respective firing angles of the SCRs such that: (i) the output voltage substantially linearly ramps from a low initial value to a relatively high final value, and (ii) charge up currents into the bus capacitor are controlled.

Abstract: A controlled DC power supply for a refrigeration appliance is disclosed for reducing heat dissipation and power loss. The refrigeration appliance has AC-powered components, such as compressors and fans, and DC-powered components, such as relays and solenoids. The relays operate to supply AC power from an AC input to the AC-powered components. The relays are selectively activated or deactivated by the controller through enable signals in response to factors such as time and/or temperature. The power supply has an AC-to-DC power conversion circuit for converting AC power at an AC input to one or more DC power outputs for powering DC-powered components. When a group of DC-powered components powered by the same DC power output, such as a group of relays, do not require DC power, the controller selectively disables or reduces a portion of the AC-to-DC power conversion circuit to reduce power consumption and heat dissipation therein.

Abstract: A soft start bridge rectifier circuit is described for controlling the operation of the bridge rectifier in order to ramp up the DC output upon connection with the AC input in order to limit in-rush current. Additionally, short-circuit/overload protection, temporary line loss protection and undervoltage checking circuitry is provided.

Abstract: Device designed to control a coil forming part of a solenoid valve, for example in a contactor type device.A switching power supply 14 includes a winding S1 powering a control circuit 15 and another winding S2 placed with a switch T2 at the coil terminals. Switch T2 is controlled by the control circuit to power the coil in the hold phase starting from the switching power supply. This reduces disturbances during the hold phase.

Abstract: The AC-DC converter comprises a first rectifier circuit having a three-phase input and an output in DC. A compensating device is connected between the input and output of the first rectifier circuit to compensate the stray disturbances generated by a current flowing in said first rectifier circuit. The compensating device makes a compensation current flow between the three-phase input and the DC output. Said compensating circuit comprises a second rectifier circuit with controlled rectifiers connected to the three-phase input, a step-up circuit connected between the second rectifier circuit and the DC output, and a control circuit to control the step-up circuit and the second rectifier circuit.

Abstract: AC/DC transformer for tapping power from an electric current loop (1) for current supply to a functional unit (2), whereby the current loop (1) conducts an alternating current preferrably having a constant frequency and amplitude for the current supply. The converter has an inductive coupling (4) to the current loop (1) and the latter constitutes a primary winding in the inductive coupling (4). At the secondary side there are provided rectifier means (LR) for DC supply to the functional unit (2), a voltage regulator (SR) for controlling an electronic switch (S), a power coil (L1) and at least one capacitor. The power coil (L1) is located at the AC side of the rectifier means (LR) and a capacitor (C1) is provided in series with the power coil (L1) and together with the latter is adapted to have resonance at a frequency coinciding substantially with the frequency of the current supply.

Abstract: A solid state transformer having an input stage operatively coupled to an isolation stage. The input stage converts a high voltage, single phase AC input voltage to a plurality of unisolated DC output voltages. Each unisolated DC output voltage is at a voltage level which is less than the voltage level of the AC input voltage and each of the unisolated DC output voltages is separately isolated in the isolation stage.

Abstract: Disclosed is a power supplying circuit for a ceiling fan including a protecting unit, a power supplying unit and a rectifying unit. An operation of the power supplying circuit is divided into four cases which are a negative half cycle loop, a positive half cycle loop, a control loop and a protection loop. Using this power supplying circuit, a stable DC voltage output can be achieved for both a control purpose and a detection purpose when a load being in a series connection with the power supplying circuit varies from a low load to a high load.

Abstract: An apparatus for interconnection in a voltage-stiff converter is provided. The converter has at least one phase leg with at least two current valves. The apparatus connects a current valve with a respective pole conductor. A cable extends between an end of the phase leg and a capacitor which defines a direct voltage. The cables attached to different poles are arranged close beside each other and are made of an insulation layer of polymer base which surrounds a conductor.

Abstract: AC/DC power converter device comprising a full-wave rectifier (R) the output of which is applied to a direct current module which has two outputs: the main output is connected to the load via a capacitor (C1) which transfers a first power level (P1), and the auxiliary output is formed by a capacitor (C2) and a direct current converter (DC) which stores a second power (P2) and transfers it to the load during the full cycle of the input power wave (PE). As a result the second power level (P2) is continuously topping up the first power level (P1).

Abstract: A boost converter, a method of operating the same and a power converter employing the boost converter or the method.

Abstract: The present invention relates to a device for improving the power factor of a rectifying bridge supplied by an a.c. voltage and meant to issue a rectified d.c. supply, including two capacitors mounted in series and having different values, a first charge path essentially meant for a first capacitor, a second switchable charge path and exclusively meant for a second capacitor with a value higher than the value of the first capacitor, a first switchable discharge path and essentially meant for the first capacitor, and a second discharge path exclusively meant for the second capacitor.

Abstract: A device and associated method for limiting a current surge in a capacitor connected to the output of a rectifying bridge having its input connected to an a.c. voltage, the bridge being a composite bridge and being associated with means for synchronizing the turning-on of the bridge from zero crossings of the voltage of the a.c. power supply.

Abstract: A power factor correction device of a rectifier bridge supplied by an a.c. voltage for providing, by means of at least two capacitors, a rectified d.c. supply, comprises between two rectified supply lines a charge path of each capacitor; a switchable discharge path of each respective capacitor; a first control block for closing a first discharge path associated to a first capacitor only after the a.c. supply voltage crosses a maximum value; and a second control block for closing a second discharge path associated to a second capacitor at the expiry of a predetermined delay following the closing of the previous discharge path.

Abstract: A memory stores optimum capacitance values of a variable capacitor obtained by measuring in advance depending on temperatures. In practical use, a controller reads an optimum capacitance value from the memory according to a temperature obtained by a temperature sensor, and sets a capacitance value of the variable capacitor to the optimum capacitance value. Thus, a tuning frequency can be always adjusted to the frequency of a radio wave transmitted. Also, deviation of the tuning frequency due to variations in the production process can be remedied by varying the capacitance value according to data stored in the memory.

Abstract: A power converter including a star converter module network and a star resistive network. A feedback network monitors the voltage difference between the nodes of the star converter module network and the star resistive network, and provides a signal for each phase of an AC supply corresponding to the voltage difference. An output sensing means senses the output voltage across output terminals and produces a demand signal based on a comparison of the output voltage with a required value. A controller produces a control signal based upon this comparison for each phase, and the control signal is used to control a corresponding converter module. Applications include power converters for supplying an isolated supply from a multi-phase main supply not having a neutral connection.

Abstract: This invention is a multi-function power supply, i.e., a power-mate unit, for providing DC input to a portable electronic device, e.g., a notebook computer, operable with a rechargeable battery. The power-mate unit includes an AC plug for electrically connecting to an AC power source for receiving the AC input current. The power-mate unit further includes an AC/DC power supply for converting the AC input current to an external DC operation current suitable for operating the portable electronic device. The power-mate unit further includes a backup battery pack connected to the AC/DC power supply for receiving a backup battery charging current for charging the backup battery pack wherein the backup battery pack further providing a backup DC current to the portable electronic device. The power-mate unit further includes a backup battery monitoring and display for continuously monitoring a charge capacity of the backup battery pack and for displaying the charge capacity.

Abstract: A converter connection for conversion between alternating voltage and direct voltage, for connection to a power network (DCN) having a neutral pole (P0) and at least one pole (P+,P-) energized by direct voltage in relation to the neutral pole, comprises a voltage-source converter (VC) with two direct-voltage terminals (DP, DM). At least one of the direct-voltage terminals of the converter is connected by means of an electric pole conductor (W1, W12, W11, W21, W2) to at least one of the poles of the power network which are energized by direct voltage.

Abstract: An isolated, high impedance, DC current source is provided from a readily available AC type source. The DC current source includes an isolating transformer which receives the AC source signal and provides an isolated AC voltage signal therefrom, a resonant low pass filter which is tuned to the frequency of the AC type source and which takes the AC isolated voltage signal and generates therefrom an AC current source signal, and a rectifier which rectifies the AC current source signal to provide a DC current source signal. A voltage limiting clamp is preferably coupled to the rectifier in order to limit the output voltage to a desired level. The resonant low pass filter is preferably comprised of two substantially equally valued inductors coupled to respective poles of the secondary winding of the isolating transformer, and a capacitor which is coupled to both of the inductors.

Abstract: A power supply system particularly adapted for use with an electrostatic precipitator to provide substantially ripple-free DC power for improved precipitator operation. The power supply is adapted to receive three-phase AC power and to transform the AC power into high voltage DC power having a minimum of voltage ripple in the output. The power supply includes a multi-phase transformer having three primary windings, each of the primary windings having associated with it a pair of secondary windings. The primary windings can be either delta connected or wye connected. One of each of the secondary windings associated with one of the respective primary windings are connected together in a delta connection arrangement, and the remaining secondary windings are connected in a wye connection arrangement.

Abstract: A plumbing fixture has a housing adapted to be secured to a support surface, forming a compartment dimensioned to snugly receive a battery, and formed with a passage extending from the compartment to the surface. Contacts exposed in the compartment are positioned to engage terminals of the battery. At least one feed conduit extends from the housing through a hole in the support surface so that liquid can be fed to the housing through the conduit. An electrically controlled valve in the housing is connected to the contacts and to the conduit for altering characteristics of fluid flow through the housing. A battery simulator is provided including a battery-replacement unit dimensioned like the battery, received in the compartment, and having terminals engaging the contacts. A flexible supply cable extends from the unit through the passage and surface and has an outer end outside the housing. A fitting on the outer end can fit with a standard line-voltage supply.

Abstract: A bridge rectifier circuit uses active switches for at least two of its four rectifying elements, and employs an active control circuit to control the state of the active switches. The active control circuit receives its input from the AC input to the bridge rectifier circuit, is powered by the DC output of the bridge rectifier circuit, and provides control outputs to the active switches. In this manner, a bridge rectifier circuit having improved performance and decreased power dissipation is achieved.

Abstract: A switching method and apparatus for increasing the efficiency of an inductive motor. A switching device connects, according to a PWM process, a D.C. voltage (E) to an inductive motor creating a low-frequency contribution UmLF rising from 0V to the peak voltage at the beginning of each half period T/2. The peak voltage is maintained for at least one sixth of a period T/6 creating a plateau and, then, the switching device connects, according to the PWM process, the D.C. voltage (E) to the inductive motor for the remainder of the half period T/2 creating a low frequency contribution UmLF declining from the peak voltage to 0V. With this arrangement, motor vibration is reduced and efficiency is increased.

Abstract: The present invention is directed to a full wave rectifying circuit where a single input a.c. signal is used to perform full wave rectification with enhanced accuracy. An a.c. signal is transmitted from an a.c. signal source (1) via a coupling capacitor (3) to bases of transistors (Q1, Q4) of first and second differential gain stages (S1, S2). Outputs from the first and second differential gain stages (S1, S2) are received on input terminals of first and second current mirror circuits (K1, K2). Output currents (I.sub.011, I.sub.012) from the first and second current mirror circuits (K1, K2) are converted by load resistances working as current-voltage converting means, and then, output voltage V.sub.OUT1 rectified on the full wave basis is output from an output terminal (12). Portions of the a.c. signal out of phase from each other are rectified on the half wave basis by the first and second differential gain stages (S1, S2) and then they are added, so that a single input a.c.

Abstract: A planar transformer includes a multilayer printed circuit board having a plurality of spiral windings formed by metalization on various surfaces of the printed circuit board. A ferrite core assembly includes first and second core sections disposed on opposite sides of the printed circuit board and completely confining the conductors of the spiral windings. Each core section includes a thin, flat plate. The two flat plates are integral with or abut thin post sections that are thick enough to allow the printed circuit board to be accommodated between the first and second core sections. In one embodiment of the invention, the planar transformer is incorporated on the printed circuit board with other circuitry to form a low noise battery charger which is encapsulated in a male power connector.

Abstract: A full wave rectifier includes an amplifier having a minus input, a plus input and an amplifier output; an input resistor connected between a circuit input and the minus input; and a current bridge having an output terminal connected to the circuit output, a first terminal connected to the minus input and a second terminal connected to the amplifier output. The current bridge includes a first current mirror circuit and a second current mirror circuit. The first current mirror circuit includes a first current source and a second current source, a source end of each current source of the first and second current sources being connected to the first terminal, a drain end of the first current source being connected to the second terminal and a drain end of the second current source being connected to the output terminal.

Abstract: The invention relates to a new arrangement of at least one valve stack (2) for high voltage direct current in a valve hall (1). Said valve stack (2) has a voltage to ground which, in operation, increases along the stack (2). The invention comprises arranging the stack (2) in a substantially lying position at such a distance from the floor and roof (9), respectively, of the valve hall (1) that the smallest electrical flashover distance between live parts on the stack (2) and said floor and roof (9), respectively, is at least contained. Further, the electrical connection is arranged via bushings through the roof (9) of the valve hall (1).