Abstract: A high frequency power supply for supplying a yielding current through a choke to a welding station including an electrode element and a workpiece element, wherein the power supply includes a transformer means for creating a first current pulse in a first secondary winding and a second current pulse in a second secondary winding and means for connecting said secondary windings to pass said current pulses through said choke and across said elements.

Abstract: A pulse width modulated DC to DC voltage converter for producing selectable differential output voltages. A feedback voltage and a selectable error voltage are fed back to the controller to control the pulse width by the difference between them. First and second power switches are respectively operable in response to first and second square wave signals output from the controller. The converter includes a center-tapped transformer having first and second output terminals. The outputs from the first and second output terminals are filtered and rectified into respective nominally positive and negative DC output voltages. A first selector switch for selectively connecting the nominally negative voltage output terminal to either a grounded bus or a negative bus is mechanically ganged to a second selector switch having a plurality of positions for selecting one of a plurality of predetermined error voltages.

Abstract: An output voltage of an A.C. power source is input to an frequency converter and the frequency thereof is increased. A plurality of high voltage transformers of small capacity each of which has a secondary winding of a small number of turns and which are connected in parallel with one another are connected to an output terminal of the frequency converter. Outputs of the high voltage transformers are respectively connected to high voltage rectifier circuits. Outputs of the high voltage rectifier circuits are serially coupled, the output voltages thereof are added together, and the addition result is applied to an X-ray tube. Combinations of the high voltage transformers and the high voltage rectifier circuits are molded into units one or a preset number at a time with solid insulating material including gel insulating material.

Abstract: In one embodiment, a solid state DC power supply includes an inverter (30) having two half-bridges (32, 34) in which are provided pairs of MOSFETS (Q5-Q12) used as switching elements. An output transformer (60) and a rectifier (85) are connected to output terminals (T60). A feedback path includes switching control means (40) separate primary and secondary drive means (10, 20) supplying drive pulses to the switching means (Q5-Q12) in the inverter (30). The secondary drive means (12, 13) amplifies the pulse output of the primary drive means (11) in order to improve the switching speed of the inverter (30). Current detection is provided by a transformer (70) connected to switching (40). The primary and secondary drive means receive pulses from a pulse width modulator (IC5) the output of which is isolated by transformers (TX1, TX2). In a modification, a power converter in the form of a DC power supply includes parallel MOSFET (M) and IGBT (I) switch pairs in each arm of a full wave bridge configuration.

Abstract: A bi-directional converter offers power conversion between both 270 volts to 28 volts and 28 volts to 270 volts. The converter utilizes common magnetic components such as a transformer and a filter inductor and dual function built/in diodes across transistors. The converter also utilizes a bridge converter, a push-pull converter, and a boost converter.

Abstract: A DC-to-AC power inverter includes a transformer with a secondary winding and a center-tapped primary. The center tap is connected to one pole of the DC source, and each end of the primary winding is connected to the other pole of the source by a switch. The switches are controlled in a 50% duty cycle mode, a mode in which both switches are ON simultaneously, and/or a mode in which both switches are periodically OFF simultaneously. The both-ON switch condition short-circuits the transformer, with the result that more current flows through the inductor, which has the effect of boosting transformed voltage above that of the 50% duty cycle mode. The both-OFF mode reduces the inductor current and decreases the transformed voltage. The amount of overlap of the both-ON and both-OFF conditions controls the output voltage. A rectifier arrangement may be coupled to the secondary winding to convert the AC output voltage to DC.

Abstract: New topologies for pulse width modulated resonant DC/DC converters are disclosed. The converters include a bridged chopper to convert the DC input to a high frequency AC which in turn is fed to a high frequency transformer whose secondary AC is rectified and filtered to produce a stable DC output. The bridged chopper has at least two semiconductor switches which alternately conduct. The duty cycles of the conduction of the switches are complementary with one another and adjustable to control the stable DC output. A resonant circuit is connected between the chopper and the high frequency transformer and contains a series capacitor, and a series or parallel inductor depending upon the preferred embodiment.

Abstract: A switched multi-tapped transformer-based power conversion circuit is disclosed. A polarity alternator comprising dual switch devices controlled by a microprocessor selectively periodically impresses across a transformer's center-tapped primary winding a voltage from a battery to produce a modified square waveform. Each of the taps of the transformer's secondary winding synchronously selectively switched by the microprocessor to a common wired-OR junction where the discrete voltage levels combine to produce a stepped approximation of a stored sine waveform. The switching circuits for each of the taps comprises dual back-to-back series-connected FET switches with diodes shunting each FET's source and drain.

Abstract: In a compensating arrangement for a disturbed load voltage (V.sub.2, FIG. 3) of a remotely located load (20), the load voltage is fed back and combined with the voltage (E.sub.osc) of an oscillator (10A) to form an error signal (E.sub.X). The error signal is stored for a period less than one cycle of E.sub.osc by a selected period (T) and combined with the oscillator voltage (E.sub.osc) to be amplified and produce a modified output voltage (V.sub.O). The latter, when fed to the load through a distribution system (15) results in the waveform of the load voltage (V.sub.L) being substantially identical to that of the oscillator voltage (E.sub.osc).

Abstract: A switching regulated power supply, the output voltage of which is regulated according to a pulse width modulation method, is provided with a reference oscillator for generating first and second synchronizing signals, phases of which are complement each other, first and second time constant circuits, to which the first and second synchronizing signals are supplied respectively, each one of the circuits having a resister and a capacity device including a variable capacity diode, charge speed up diodes coupled in parallel with the resisters, first and second CMOS drive circuits for inputting the output signals of the first and second time constant circuits and for providing drive signals according to the output signals, a DC-DC converter having push-pull switching devices driven by the drive signals of said first and second CMOS drive circuits, and a control circuit for detecting an output voltage of the DC-DC converter and for controlling capacitance of the variable capacity diodes of said first and second tim

Abstract: High efficiency, post regulation of auxiliary outputs in multiple output-power supplied is provided by connecting a regulating switching device in parallel with a filter inductor connected in the current path from the rectifiers to the output terminal. For minimum output power for that auxiliary output, the switching device is held off at all times. When increased power is required, the switching device is turned on for a short period during each cycle of the inductor voltage. The switching system may be configured to conduct current from the output end of the inductor to the input end of the inductor or vice versa or either one selectively, in accordance with the particular regulation scheme chosen. Efficiency is maximized since current flows in the switching device for only a small portion of each cycle of the inductor voltage.

Abstract: Method and apparatus for output current limitation of a push-pull d.c. voltage converter. The input current of the push-pull d.c. voltage converter is detected and integrated each switching cycle of push-pull switches in the current paths leading to the transformer of the converter. The integrated signal together with a reference signal are utilized to form a control signal for a pulse frequency modulator, the output of which controls the on-periods of the push-pull switches. The arithmetic mean of the output current of the push-pull d.c. voltage converter is thereby kept constant without additional power elements. Operation with a boost-type switch controller as a pre-regulator becomes possible without problems.

Abstract: In a regulated power supply, particularly a pulse-width-modulated supply, the on-off control is located in the feedback path between the supply output terminal and the pulse-width-modulator. Transformer coupled polling pulses sense both the state of the on-off control and the magnitude of the feedback error signal.

Abstract: Disclosed is a direct current (DC) to alternating current (AC) converter (5) that receives a direct current signal from an input power source (10) to drive a load (2). A power module (16), controlled by a central processing unit (CPU) (14), includes a DC-to-DC voltage booster (20) that boosts the direct current signal from approximately 12 volts to 150 volts. A DC-to-AC inverter (70), which is also controlled by the CPU, converts the boosted DC voltage from DC to a 60 Hz AC output signal (18) used to drive the load. The power module includes a voltage feedback path and a current feedback path for regulating the AC output voltage signal in response to changes in the load (12). The voltage feedback path includes a fast integrator (36) connected in parallel with a slow integrator (34).

Abstract: A standby power supply system (SPS) is connected to supply power to a load by way of a transfer switch, to replace power from the AC lines, when the AC line fails to provide sufficient voltage to operate the load (e.g., 85% of nominal RMS voltage usually 120 VAC-RMS). The SPS has an inverter which switches voltage from a battery to generate AC power when the line fails. The inverter is controlled by varying the width of switching pulses in order to regulate the AC output voltage and compensate for reductions in battery voltage as the battery discharges. The AC output voltage is also synchronized with the line voltage when the line voltage returns (increases to greater than 85% of nominal value) so that on switch over back to the AC line, the AC waveform applied to the load does not change substantially before and after switch over.

Abstract: This invention reduces the ripple component of current in the alternating current to, or direct current from, a common power source providing direct current power to a plurality of switched dc/dc power supplies by controlling the time of occurrence of switching of each of the supplies. Each dc/dc power supply is controlled by a switch pulse from a switching circuit which determines the occurrence and duration of time during which each power supply is switched "on". The time of occurence of the switch pulse of each switching circuit is determined by the application of an individual synchronizing pulse to each switching circuit. The combined effect of the ripple components of currents provided to the switched power supplies is minimized by summing these currents with appropriately phased synchronizing pulses applied to the switching circuits.

Abstract: A switching circuit having an input voltage source for producing a DC voltage, a transformer having a pair of inductively coupled primary windings, a controller for electrically coupling the produced DC voltage across a first one of the pair of windings during a first portion of a cycle to induce a voltage in a second one of the pair of windings during such first portion of the cycle and for electrically coupling the produced DC voltage across the second one of the pair of windings during a second, subsequent portion of the cycle to induce the voltage in the first one of the pair of windings during the second portion of the cycle, and a circuit, responsive to the and in response to a level of the voltages induced in the pair of windings exceeding a predetermined voltage, for directing energy related to the excessive voltages back to the voltage source means.

Abstract: A circuit for regulating an electrical parameter to be servo-controlled by transferring electricity between two networks (11, 12), wherein the circuit (10) is a bidirectional current circuit providing electrical isolation between the two networks (11, 12). The circuit is particularly applicable to space applications.

Abstract: A switching circuit which provides excess voltage and a circuit, responsive to the excess voltage, to direct energy related to the excess voltage back to a voltage source coupled to the switching circuit is described. The circuit responsive to the excess voltage includes a capacitor, an inductor, and a transistor to couple and decouple the capacitor and the inductor. The transistor couples the capacitor to the inductor to transfer energy related to excess voltage stored in the capacitor to the inductor for storage, and decouples the capacitor from the inductor to transfer energy stored in the inductor to the voltage source. The circuit also includes a comparator, responsive to the level of the excess voltage, to provide a control signal to the transistor to control the coupling and decoupling of the capacitor and the inductor.

Abstract: In a digitally controlled amplifier circuit a dc power source is modulated by an oscillator signal for producing a reference square wave signal. A sawtooth signal, double the frequency of the reference signal and synchronized therewith, is compared with a variable input signal to be amplified. When the sawtooth exceeds the input signal a phase shifted version of the reference signal, shifted in phase in accord with the instantaneous amplitude of the variable signal is produced. A switching circuit logically governed by the reference and phase shifted signals produce a pulse width modulated output signal of a selected polarity. An output filter smooths the pulse width modulated output signal and steering diodes control the polarity of the switching circuit.

Abstract: A power converter is provided with a split primary current fed push pull topology. An inductor connects the primary windings. Controllable switches provide alternate circuits from the dc source inputs through each of the primary windings and the inductor. Clamping diodes connect the ends of the inductor to the dc source inputs opposite to those provided by the controllable switches. The clamping makes cross conduction unnecessary. Separate duty cycle control is provided in each primary circuit.

Abstract: An AC power source apparatus to be used in an AC corona generator necessary for a de-electrification/separation process, which is one of electrographic image forming processes, or in a case where a low frequency AC power source is required, has a construction such that a high-frequency pulse, whose time ratio is modulated trapezoidally with time, is applied to switching elements connected in inverse-series across a primary winding of a transformer, an inductance element having a regenerative diode and a reset winding is inserted between an intermediate tap of the primary winding of the transformer and a DC power supply input terminal, and an LC filter is formed by stray capacitance of a secondary winding of the transformer, whereby a desired output waveform can be produced with a simple circuit construction.

Abstract: A load is controlled by a pulse waveform from a source. The source and load are electrically isolated by using two monostable circuits to detect the leading and trailing edge of the pulse waveform, two pulse transformers to isolate the source and the load, and a bistable circuit to reconstruct the original pulse waveform.

Abstract: A switching power source device provides a desired AC/DC output by producing a pulse width-modulated waveform through ON-OFF control of a pair or pairs of switching elements connected in series with an input power source, eliminating high-frequency components of the pulse width-modulated waveform with a smoothing choke. The switching power source device is configured so that the input power source will not be short-circuited and consequently suffer a voltage and/or current surge, even when both switching elements in the pair assume the ON status at the same time by dividing the smoothing choke into two portions. The two portions of the smoothing choke are connected in series with the input power source when the switching elements in the pair assume the ON status at the same time.

Abstract: A dual transformer device (34) for use in a power converter (30) is provided. The dual transformer device is preferably implemented as an integrated magnetics device suitable for use in high density power converters. Two transformers, T1 and T2, have series connected primary windings (300 and 302), and secondary windings (304 and 306) connected at a common node (312). T1 and T2 have magnetizing inductances, L1 and L2, that independently store energy responsive to an AC voltage, V.sub.p. Diodes, D1 and D2, operate to rectify substantially out-of-phase secondary voltages, V.sub.S1 and V.sub.S2 and produce a rectified voltage V.sub.R. D1 and D2 cause L1 and L2 to store discharge energy such that the magnitude of an output current, I5, is always equal to the sum of magnetizing currents, I.sub.L1 and I.sub.L2. An output filter (38) reduces current ripple in I5 and voltage ripple in V.sub.R. Another inductance, L3, supplies energy to an AC voltage supply (32) to reduce switching losses.

Abstract: The present invention provides a power drive circuit which is transformer isolated from the circuit developing the drive signals, but which does not lose its DC reference voltage. This technique results in the desired isolation without the undesirable possibility of operating the output transistors in an unsafe DC region, which is a particular problem when the output transistors are FET devices. In accordance with the present invention, pulse transformers are used to drive the power FET devices.

Abstract: An energy transfer arrangement in which a primary network transfers controlled quantities of energy to a secondary network. The primary network signals to the secondary network when it is about to initiate energy transfer and then initiates energy transfer until the secondary network responds to indicate to the primary network that energy transfer is to be terminated. The secondary network delays sending the primary network a termination signal for a period of time until the primary network is ready to receive the termination signal. The sequence of the primary network signalling the start of energy transfer, the primary network transferring energy, and the secondary network signalling the termination of energy transfer, is repeated indefinitely.

Abstract: There is provided an improvement in an inverter power supply of the type including an output transformer of the type having a high permeability magnetic core, input winding means for applying input current pulses to the core; a first output winding wound on the core; and a second output winding wound on the core. The power supply further includes first and second output terminals and output circuit means for connecting the individual output windings to the terminals in a fashion that opposite polarity output current pulses induced in the output windings by the input current pulses are applied across the terminals in a preselected first polarity.

Abstract: A control circuit is provided for the output of a high frequency inverter of the type having an output transformer with a core, primary windings and a secondary winding with two sections for creating a first secondary current pulse of electrical current in one section when the primary windings magnetizes the core and a second secondary current pulse in the other of the secondary sections when the primary windings remagnetizes the core. By alternating switch means for passing current through the primaries to magnetize and remagnetize the core at a preselected rate the output current pulses are provided by the two sections of secondary windings. The control circuit of the present invention involves a modification of the output transformer secondary stage. A first auxiliary winding is connected to one of the secondary sections to create an auxiliary current pulse as the core of the transformer is magnetized.

Abstract: A flyback converter high voltage power supply which includes two switches operating in push pull fashion to provide alternate polarity energy pulses to a load. A main component of the power supply is a transformer, the primary winding of which is divided into halves. The secondary may be also be split into halves, or may be configured without a split so long as the secondary and rectifier combination result in full wave rectification. The first of the two switches couples an input voltage across the first primary half to store energy in the magnetic core during a first time interval, and at the end of the first time interval disconnects the first primary half from the input voltage. During a second time interval, the energy stored in the magnetic core during the first time interval is delivered to the load via the secondary winding.

Abstract: A power supply for a Xenon lamp of a projection television includes a pulse-width-modulator that is included in a power regulating outer feedback loop and in a current-mode inner feedback loop. A current sensing transformer, responsive to a current in a chopper arrangement of the power supply, generates a signal that is coupled to a lowpass filter. The filter generates a ramping portion of each pulse of a control signal that is coupled to a current sensing terminal of the pulse-width-modulator. A switch operating synchronously with a horizontal sync signal is coupled across a capacitor of the lowpass filter to completely discharge the capacitor prior to the beginning of each ramping portion.

Abstract: A single stage power conditioner which produces an isolated DC output while drawing resistive input current from the utility has been described. A high frequency switch-mode technique was used which operates in continuous conduction mode to reduce electro-magnetic interference (EMI) generation and ripple losses.

Abstract: A dc converter for supplying an electronic device in which a feed voltage is summed with an additional voltage generated by rectification and wherein pulse-width control is provided at the primary side of the converter transformer. According to the invention, the additional voltage is generated by rectification in the same manner as the main output voltage is generated, i.e. the rectifier circuit outputting the additional voltage is similar to that outputting the output voltage.

Abstract: A new type of power source switching circuit is disclosed. In the device of the present invention, a relay is used instead of semiconductor elements which are used in the conventional types of power source switching circuit. Compared with the conventional ones, the circuit according to the present invention is much simpler, and assures the protection of the circuit against damages due to an overvoltage or impact pulses, which damages are liable to occur in the conventional types of power source switching circuit.

Abstract: A power supply for an arc lamp. It includes a DC converter which has an input, an output, and a circuit for increasing the voltage received at the input and for supplying the increased voltage to its output. A current sensing circuit is provided for controlling the amount of current delivered to the output. An output "H" bridge is coupled to the output of the DC converter for generating a squarewave in response thereto. The power supply is capable of quickly igniting and re-igniting arc lamps, is relatively inexpensive to manufacture and it relatively light in weight. The power supply can accept either an AC or DC source over a wide voltage range and increases or decreases the input voltage compared to the output voltage.

Abstract: A conversion circuit is provided which includes a negative temperature coefficient resistance between a rectifier and a storage capacitor to limit inrush current when power is applied to the circuit after a power interruption of a relatively long duration. When power is resumed after a short term power interruption and the resistance of the negative temperature coefficient resistance is still low, inrush current is limited by disconnecting a load from the conversion circuit immediately upon the occurrence of the power interruption to maintain the charge on the storage capacitor for the duration of the interruption. A boost regulator unit is provied between the negative temperature coefficient resistance and the storage capacitor to provide a regulated direct current potential across the capacitor which is not responsive to input power variations.

Abstract: Improved load regulation is provided in a switched mode power supply having an integrator, with a controlled reference signal connected thereto, a comparator circuit and a square wave generator, connected to the terminals of an AND circuit, and AND circuit connected to a power driver outputting to a transformer having two secondary windings. A current sensing resistor connected to the power driver is fed back to the comparator where this current level is compared with the integrator output. A first secondary winding is connected through a diode to the load with a capacitor connected across the load and a second secondary winding is connected in a feedback line to the integrator with a series diode, a capacitor is connected across the second secondary winding with a voltage divider connected across the second secondary line in parallel with the capacitor. The above arrangement is for current mode topology and an alternate arrangement is shown for voltage mode topology.

Abstract: Improvement for power supplies include a protection circuit having a first L-C filter network, a second L-C filter network and a voltage clamping device such as a zener diode which is disposed between the two L-C filter networks. The protection circuit reduces the magnitude of overvoltage input transients which might otherwise damage the internal components of the inverter. For generating very high output votlages, the power supply includes a high voltage transformer and a Crockoft-Walton voltage multiplier coupled thereto. The high voltage transformer is coupled to an inverter through a coupling circuit which includes a capacitor in one leg of the primary winding and a parallel connected resistor/inductor in the other leg of the primary winding of the high voltage transformer. The high voltage transformer is formed of a multi-sectioned bobbin which is defined around an axially extending core.

Abstract: A switching power supply includes push-pull power switches driven by first and second conjunction gates. The conjunction gates are coupled to receive the output of a flip-flop, together with the antiphase outputs of a binary divider which divides down the output of the flip-flop. The flip-flop is driven recurrently by sync to enable one of the conjunction gates, and the binary divider steers the enablement alternately. When the output voltage or current crosses the design threshold, a comparator is triggered to produce a shut-down signal which is applied to the reset input terminal of the flip-flop to reset it. Delay in the flip-flop is avoided by also applying the shut-down signal to the conjunction gates. The maximum possible duty cycle is extended by initiating switch conduction at a predetermined short time after initiation of the sync pulse.

Abstract: In an inverter type X-ray apparatus comprising an inverter including a plurality of switching elements operated alternately to generate an AC voltage having a rectangular waveform, a high voltage transformer transforming the AC voltage of rectangular waveform into a high AC voltage, a high voltage rectifier circuit rectifying the high AC voltage into a DC voltage, and an X-ray tube to which the DC voltage is applied as a tube voltage, the switching elements are driven to make chopping operation at a frequency high than the inverter drive frequency, and a pattern signal is generated for gradually increasing the duty cycle of the chopping operation in synchronism with the timing of switching over the switching elements.

Abstract: An improved DC to DC conveter is disclosed which is highly stable and has a highly regulated ouptut voltage. A pulse width modulator drives a switch for interrupting the flow of current through an inductor. A combination of feed forward and feedback control of the pulse width modulator is provided with the majority of control being provided by the feed forward component. The pulse width of the pulses from the width modulator is directly proportional to the feed forward and feedback components of the pulse duration control signal. Preferably, approximately 75%-90% of the pulse duration control signal is provided by the feed forward component.

Abstract: A power supply includes a source of first and second switching signals that are at opposite phases. First and second MOS power transistors have main current conducting electrodes coupled to a transformer and have gate electrodes that are respectively coupled to the first and second signals to provide push-pull operation. When a transition occurs in a first one of the MOS transistors from a conductive state to a nonconductive state, a voltage is developed at its gate electrode due to its input Miller capacitance. The gate electrode voltage is coupled to a control terminal of a controllable attenuator that attenuates the switching signal that is coupled to the gate of the other MOS transistor. This delays the initiation of the conductive state in the other MOS transistor until immediately after the first transistor becomes nonconductive, thereby avoiding simultaneous conduction in the two transistors.

Abstract: A pulse width modulation control circuit utilizes a retriggerable monostable multivibrator as a high speed comparator which compares a reference waveform with a control signal level to effect variable termination of modulated output pulses. The control circuit finds particular applicability to pulse width modulated switched mode power supplies.

Abstract: A power transfer arrangement provides regulated power transfer from a station to a contactless portable data card without the need for regulation circuitry on the card itself. The station includes a primary coil for magnetically coupling power to a secondary coil, located on the card, when the data card is brought into close association with the station. The arrangment includes a microprocessor, a power amplifier including the primary coil, a variable voltage source and apparatus for measuring current flow in the primary coil. When the portable data card is not in close association with the station, the microprocessor causes the variable voltage source to provide a sequence of stepped voltages. Quiescent current flow is measured at each step and stored in memory. When the portable data card is brought into close association with the station, the microprocessor causes the variable voltage source to provide a sequence of stepped voltages. Active current flow is measured at each step and stored in memory.

Abstract: An inventive oscillator, inter alia, is disclosed which can be used to generate a frequency modulated control signal or a pulsewidth modulated control signal for application to a switching means in a switching power supply. The output voltage of a power supply is used to control the magnitude of a high bias voltage and a low bias voltage applied to a plus terminal of a voltage comparator, wherein when the output of the voltage comparator is high, the high bias voltage is applied to the plus terminal, and when the output of the voltage comparator is low, the low bias voltage is applied to the plus terminal. A capacitor, coupled to the output of the voltage comparator via a resistor, is coupled between the minus terminal of the voltage comparator and a ground so that when the output of the voltage comparator is high the capacitor charges.

Abstract: An electronic AC voltage stabilizer using a class B amplifier output stage which is fed by a full-wave rectified sinewave voltage. The input voltage to (the phase inverter of) the class B amplifier output stage is kept in phase with the aforesaid sinewave voltage, which causes the power losses in the output stage to be very low. As compared to other electronic AC stabilizers, the apparatus according to the invention offers high efficiency and simplicity. The AC stabilizer can easily be converted into a true uninterruptible power supply (UPS) by adding a battery which through a battery interface circuit connects the battery voltage, after it has been appropriately converted into a full wave rectified sinewave voltage, to the push pull amplifier output stage when a power network fails.

Abstract: An X-ray generator system has first and second switching devices such as transistors which are complementarily turned on and off to intermittently apply a DC voltage to the primary winding of a transformer for thereby inducing a high voltage across secondary windings of the transformer for enabling an X-ray tube to emit X-rays. The X-ray generator has a control mode in which the first and second switching devices are simultaneously turned on immediately before they start being complementarily turned on and off, for allowing the high voltage to have a sharply rising positive-going edge.

Abstract: An apparatus for allowing the use of unmatched transistors in a power supply is shown. A potentiometer (482) and a switch (481) divert base drive current away from the transistor having the higher Beta so that the collector currents of the two transistors (477, 484) can be matched. Heat sensitive resistors (480, 483) are thermally connected to the opposing transistor (484, 477) so if the temperature and collector current of one transistor should increase the base drive to the other transistor is automatically increased, thereby causing the collector currents to remain matched. The total collector current provided by the transistors (477, 484) is limited to a safe value by a regulating pulsewidth modulator (457). The use of additional protective diodes (468, 469, 478, 479) prevent transient voltages from affecting the transistors (477, 484) and allow the use of lower power, less expensive transistors.

Abstract: An automatic symmetry correction circuit is provided for a symmetrical current chopper. This structure includes two current channels controlled alternately by two signals of frequency f.A resonant LC circuit is tuned to the frequency f and energized by the currents passing through each of the two channels.A control circuit is coupled to the resonance circuit for adjusting the symmetry between the amplitudes of the currents flowing through each of the two channels as a function of the amplitude of the oscillations of frequency f generated by the resonance circuit.

Abstract: The invention relates to a stabilized high voltage source the output voltage of which may be regulated in wide range, whereby the adjusted output current is constant at variable load. The high voltage supply source comprises a high voltage rectifier fed by a push-pull driving circuit, a control circuit supplying push-pull width modulated control signals of the driving circuit and an error signal processing circuit working up the divided voltage and current signals taken from the output of the high voltage source. The output signal of the error signal processing circuit is applied to the control circuit as a control signal. The supply voltage of auxiliary circuits of the supply source is provided by a stabilized low voltage supply unit.