Abstract: A DC to AC power converter is disclosed which is connectable to a DC source, and including a first and second pair of switches which converts the DC source directly to AC by alternately switching between each of the first pair of switches at high frequency modulation, and between second pairs of switches alternately switching at each of the half cycles of the low frequency fundamental output voltage, for producing a positive pulse train and a negative pulse train. A transformer boosts the source voltage to the desired high voltage of the output of the converter circuit. A filter is connectable to an AC load and having a plurality of damping modes for extracting fundamental frequency from the output of the transformer, and having a control responsive to a signal for switching between damping modes. A sine wave oscillator generates a sine wave at the fundamental frequency. Feedback circuits maintain the AC output at the fundamental frequency.

Abstract: The converter comprises a transformer having two primary windings; a voltage source having one of its terminals connected to the center tap; and two switches connected in series between the other terminal of the voltage source and a respective one of the primary windings, the switches having stray capacitances that impose a transition time between one of the switches switching OFF and the other switch switching ON. The transformer comprises a magnetic circuit having a gap, and each primary winding has a number of turns that is determined essentially as a function of the level of losses acceptable within the magnetic circuit, the size of the gap then being adjusted, taking account of the number of turns and the operating frequency, in such a manner as to reduce the magnetizing inductance of the transformer to a value such that said transition time is less than a given threshold corresponding to tolerances of the form factor.

Abstract: An inverter for supplying electrical energy from a DC supply to a load, includes a flyback transformer having a primary winding circuit coupled to the DC supply, and a secondary winding circuit coupled to the load. The primary winding circuit includes a first switch for interrupting the DC supply causing energy to be stored in the transformer, and the secondary winding circuit includes a second, unidirectional switch to produce an output of one sign when closed. The primary winding circuit further includes an electrical device effective to return energy to the DC supply only when the first and second switches are open.

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 driving circuit for an inverter microwave oven which includes a push-pull voltage type inverter circuit having two sets of switching element groups each provided with more than two switching elements connected in parallel to each other for switching the D.C. current supplied from a D.C. power source, a control device arranged to set a period for simultaneously turning OFF the two sets of switching element groups and to alternately turn ON the switching element groups by the same duty cycle, a step up transformer supplied, at its primary winding having a center tap, with A.C. current from the inverter circuit, and a voltage doubler rectifier circuit connected to a secondary winding of the step-up transformer for supplying electric power to a magnetron through a capacitor.

Abstract: A circuit for converting on d.c. voltage to another d.c. voltage including a transformer having a center tap and first and second end leads. A d.c. source voltage is connected to the center tap of the transformer. The end leads are connected to ground through first and second MOSFETs and to the gate of the MOSFET through which the other end lead is connected to ground such that the circuit is nominally self-oscillating due to transformer saturation. Current spikes may be minimized with a control circuit, consisting of an oscillator, a flip-flop, and first and second transistors, connected to the gates of the first and second MOSFETs. The control circuit turns the MOSFETS off prior to their natural oscillation turn off caused by transformer saturation. The circuit is particularly suited to operation with a low voltage d.c. source and low voltage MOSFETS.

Abstract: A self-oscillating DC to DC voltage converter having improved efficiency. The high efficiency saturable core voltage converter 100 of the present invention provides an output voltage across an output load R.sub.L in response to the input voltage at a source node 106 of a voltage source 104. The present invention includes a transistor switching network 120, 122 coupled to the source node 106. The switching network 120, 122 generates an alternating voltage in response to oscillation of the flux within a magnetic core 116. A voltage transformer 110 then impresses an output voltage across an output load R.sub.L, thus providing a load current I.sub.L. The inventive converter 100 further includes a feedback winding 112 for providing a transistor drive current to the transistor switching network 120, 122. A portion of the transistor drive current is shunted to the source node 106 by a source feedback arrangement 126, 130.

Abstract: A zero voltage switching DC/DC converter comprises a transformer with two opposed primary windings between which is a center tap and at least one secondary winding connected to a load by a rectifier and capacitor filter circuit. A first terminal of a constant voltage supply is connected to the center tap of the transformer. Two switching units are each connected in series between the second terminal of the voltage supply and a respective primary winding. The switches connect the second terminal of the voltage supply alternately and periodically to one or the other of the primary windings. A control device imposes between opening of one switch and subsequent closing of the other switch a switching time during which both switches are open.

Abstract: Current-fed push-pull converter. In a current-fed push-pull converter that is composed of a step-down regulator and of a push-pull controlled transformer, the transformer is connected following the step-down regulator. The converter also has push-pull switches, a transformer unit and at least one DC voltage top circuit for a respective output DC voltage. The transformer unit is formed by an auto transformer.

Abstract: Magnetic direct current to direct current converter with the input isolated from the output. A pulse generator from the feedback is incorporated in the feedback circuitry to regulate the output relative to the input.

Abstract: This invention relates to a push-pull inverter used, for example, as a driver for cold-cathod discharge tube, hot-cathode discharge tube, etc.According to this invention, respective control electrodes of a first switching element and a second switching element are interconnected by a capacitor so that a load current passes through this capacitor and thereby alternately activates the first and second switching element.With such arrangement, a boosting transformer requires no feedback coil and it is possible to eliminate a capacitor for resonance which has conventionally been connected in parallel to a primary coil of said boosting transformer.

Abstract: A high frequency self-oscillating inverter including a snubber circuit for minimizing both turn-on and turn-off switching losses. The inverter converts a DC supply to an AC load current and includes a saturating transformer for alternatively driving first and second switching devices during subsequent unsaturated states. During the time the transformer is saturated, both switching devices are kept off.The snubber circuit includes a first capacitor across the first switching device, a second capacitor across the second switching device, and an inductance. During saturation the two capacitors and inductance form a resonance circuit, wherein the inductance has a resonant half sine wave current, one capacitor discharges, and the other capacitor charges.Turn off switching losses are made negligible by selecting capacitors such that the fall time of the corresponding switching device is much faster than the time to charge the capacitor to a significant voltage.

Abstract: A push-pull high voltage oscillator power supply circuit includes a parallel resonant LC circuit made up of a capacitor in parallel with the primary of an output transformer. The output power level of the oscillator is controlled or adjusted by gating a drive circuit of the oscillator in accordance with an appropriate timing scheme so as to control the power delivered to the load over a long time period. The drive circuit is switched on and off so as to control the transformer primary voltage by omitting a number of drive pulses, determined by the desired output pulse level, so that the oscillator self-oscillates and rings out with a decreasing amplitude of the self-oscillats and rings out with a decreasing amplitude of the self-oscillations, but never reaches a complete cut-off of the oscillations before the drive circuit is gated on to refresh the supply of energy to the oscillator.

Abstract: A self-oscillating inverter uses saturable transformer means in its positive feedback circuit. The saturation flux density of the magnetic material used in this saturable transformer means determines the frequency of inverter oscillation. A permanent magnet is rotatably mounted proximate to the saturable transformer means and is used for adjustably affecting the saturation flux density of the magnetic material, thereby correspondingly to adjust the frequency of oscillation: the stronger the magnetic flux provided to the magnetic material from the permanent magnet, the smaller the saturation flux density and the higher the frequency of oscillation.

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 push-pull high voltage oscillator power supply circuit includes a parallel resonant LC circuit made up of a capacitor in parallel with the primary of an output transformer. The output power level of the oscillator is controlled or adjusted by gating a drive circuit of the oscillator in accordance with an appropriate timing scheme so as to control the power delivered to the load over a long time period. The drive circuit is switched on and off so as to control the transformer primary voltage by omitting a number of drive pulses, determined by the desired output pulse level, so that the oscillator self-oscillates and rings out with a decreasing amplitude of the self-oscillations, but never reaches a complete cut-off of the oscillations before the drive circuit is gated on to refresh the supply of energy to the oscillator.

Abstract: There is provided a low-noise switching power supply for producing a regulated output voltage from an unregulated supply. The power supply includes a main transformer having first, second and third legs. A primary winding associated with a first leg produces an alternating magnetic flux in the core. A load winding associated with a second leg produces the output voltage from the power supply. A control winding is associated with the third leg. The regulated output voltage is compared to a reference voltage and used to operate a control circuit which alternately short circuits the control winding so as to vary the reluctance pass in the transformer and maintain the output voltage at a substantially constant predetermined value. A feedback circuit including a coupling transformer connects the primary coil to the switching circuit to improve regulation and provide a "soft start" capability.

Abstract: An impedance for short-circuit prevention is connected with a secondary winding side of a transformer of a resonant converter comprising a resonant circuit, a D.C. input source, and a switching devices. The short-circuit prevention impedance is driven by the driving current generated in a driving winding in accordance with a resonance current at the primary winding side of the transformer, thereby obviating the stop of an oscillation. The oscillation can be stopped at a timing of not generating a surge voltage in the switching devices by detecting a current returning to the D.C. input power source.

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: An improved oscillator circuit for avoiding core saturation without the need for auxiliary magnetic devices employs an emitter resistance for regulating base voltage, and a semiconductor base shunt for initiating transistor cut-off when the base voltage increases above the threshold voltage of the semiconductor shunt, the emitter resistance being preselected to activate the base shunt before the transformer core reaches saturation.

Abstract: A laser device equipped with a high-voltage pulse generator wherein the pulse generator supplies an electric energy from a dc power source in an on-off form of a supply voltage to a tank circuit through a transformer, with the switching on and off of the supply voltage being effected in synchronism with the resonance period of the tank circuit. The tank circuit stores the supplied electric energy as a resonance condition so that when the electric energy stored in the tank circuit reaches a predetermined value, a saturable reactor connected between the laser device and the tank circuit becomes saturated and the electric energy in the tank circuit is discharged to the laser device.

Abstract: A power supply for an inert gas lamp which enables automatically changing the portion of the lamp which is lit in accordance with a predefined pattern. The power supply includes an a.c. to d.c. conversion circuit, and a high frequency-high voltage transformation circuit with an input coupled to the conversion circuit and an output to be coupled to an inert gas lamp. A control or function module controls and automatically changes the voltage supplied to the transformation circuit, in accordance with a predefined pattern, and thereby causes the portion of the lamp which is lit to change in accordance with that pattern. The transformation circuit and the control module are arranged so that the portion of the lamp which is lit can be smoothly and controllably varied from zero to 100 percent of the length of the lamp.

Abstract: The invention relates to a power supply circuit for an X-ray tube for converting direct current to high-frequency pulses and including at least two transistors (8, 9) whose collector-emitter circuits are controlled by means of a pulse-width modulator (5) through base control transformers (12) in a manner that transistors (8, 9) operate in push-pull fashion, one terminal (+) of a direct-current source being connected to the collector-emitter circuit of transistors (8, 9). The collector-emitter circuit of each transistor (8, 9) is separately connected through its own transformer (23, 23a) to said one terminal (+) of a direct-current source in a manner that the primary windings (24, 24a) of transformers (23, 23a) serve as ballasts limiting the current passing through transistors (8, 9) and the secondary windings (25, 25a) is connected in series with diodes (26) between the terminals terminals (+ and -) of a direct-current source.

Abstract: A high-frequency resonant power converter transforms a relatively low D.C. input voltage to a relatively high A.C. link voltage to drive a resonant circuit. The high A.C. voltage appearing across a resonance circuit high-voltage capacitor is then transformed down to a relatively low value and rectified to obtain a desired relatively low D.C. output voltage. Use of a high A.C. link voltage eliminates low voltage operation of the resonance circuit, which would require very large resonant capacitors having high current ratings. Composite magnetic structures which combine a resonant inductor and a transformer are also disclosed.

Abstract: Uninterruptible power supply apparatus which provides for supplying ac power to equipment even if and when the primary ac power is interrupted is disclosed and comprises an ac to dc converter connected to receive the primary ac power. The output of the ac to dc converter is applied to a dc power source. The resultant output of the ac to dc converter and the dc power source is provided as a dc input to a dc to ac inverter. The dc to ac inverter comprises an output transformer having a center-tapped primary. A first switching device is connected between a first end of the center-tapped primary and the negative terminal of the dc input to provide power pulses to one-half of the center-tapped primary. A second switching device is connected between a second end of the center-tapped primary and the negative terminal of the dc input to provide power pulses to the remaining half of the center-tapped primary.

Abstract: An inverter controller for controlling an inverter having a plurality of electric valves each formed by connecting a switching element and a diode in anti-parallel with each other. On the basis of an output current command value, an ON/OFF signal is supplied to a switching element which needs to operate, and the supply of an ON signal to a switching element which need not operate is inhibited. Thus, it becomes unnecessary to provide dead time which has heretofore been needed.

Abstract: In one embodiment, the high frequency-high voltage power module includes an output transformer having a first primary winding and a first secondary winding and a second transformer, that is saturable, having a second primary winding and a second secondary winding. The AC power applied to the power module is converted to a substantially direct current by a diode, a capacitor and a thermistor. A center tap on the first primary winding is connected to the positive side of the capacitor. Either end of the first primary winding of the output transformer is connected to a respective end of the second primary winding of the second transformer via a respective resistor. The center tap on the second secondary winding is connected via an RC circuit to the negative side of the capacitor. A pair of switching transistors operates in a balanced push-pull relationship and is switched by the current flowing through the divided windings of the second secondary winding.

Abstract: A power converter is provided with a pair of auxiliary windings coupled to the primary windings of the output transformer which serve as energy choke windings. An additional pair of choke windings are coupled between the input of the converter to a common terminal of the primary winding. These choke windings prevent excess voltage from appearing across the switching devices of the converter during the turn-off portions of the cycle.

Abstract: An oscillator circuit for generating a square wave output for space or terrestrial applications comprising a main oscillator and a saturable transformer forming the feedback loop of the power inverter. According to the invention, a synchronization circuit comprises transistors for shortcircuiting respective branches of the primary winding of this transformer upon detection of signal from differentiators connected to the main oscillator. Means connects a main limiting resistor to the center tap of the primary winding so that flux inversion is effected in the saturable transformer at the end of a power inverter recovery time.

Abstract: An inductive device composed of a bead (10) of magnetic material, such as ferrite, has an aperture through which an electrical conductor (13) is adapted to pass and a reset winding (14) wound thereon and connected to a source of constant current. The constant reset current resets the bead of magnetic material so that the maximum volt-second absorbtion capability of the bead is available for preventing destructively high current spikes from flowing through the electrical conductor. The inductive device is advantageously used in the d.c. supply of the power transistors (101 and 102) of an inverter (100) to protect the transistors from current surges due to the simultaneous conduction of the transistors.

Abstract: A push-pull inverter is supplied from an inductively current-limited DC voltage source by way of a center-tap on a transformer having significant inductance. This transformer inductance is parallel-coupled with a capacitance means. The inverter is made to self-oscillate through positive feedback provided by way of a saturable current transformer. The inverter frequency is determined by the saturation time of this current transformer, which saturation time is designed to be longer than the half-cycle period of the natural resonance frequency of the transformer inductance combined with the capacitance means. The resulting inverter output voltage may be described as a sequence of substantially sinusoidal half-cycles interconnected with periods of zero-magnitude voltage. By controlling the length of the saturation time, the effective magnitude of the inverter output voltage is controlled, thereby permitting control of the amount of power provided to a load connected thereto.

Abstract: A resonant current-driven power source is disclosed. Preferably, the power source is a DC to DC converter regulator including a inductor and capacitor electrically coupled to one another and an input inverter which converts an input DC voltage into an AC voltage having substantially no DC component and applies the AC voltage across an LC circuit in a manner which causes the inductor and capacitor of the latter to resonate with one another whereby an AC voltage appears across the capacitor. An output circuit converts the AC voltage appearing across the capacitor into a DC output voltage. A control circuit is provided for controlling the operation of the inverter circuit in a manner which controls the magnitude of the output voltage. The inverter circuit also includes a step-up transformer for increasing the magnitude of the AC voltage across the LC circuit to a value many times greater than the input DC voltage.

Abstract: A power conversion device of simple configuration for a solar cell which permits the solar cell to be connected to the commercial power source and enables the maximum electric power corresponding to the amount of incident sunlight to be drawn from the solar cell.A power conversion device for a solar cell of this invention comprises a voltage controlled oscillator capable of generating oscillation with a frequency which is the function of the dc output voltage of said solar cell, an inverter controlled based on the output frequency of said voltage controlled oscillator to receive the dc output current of said solar cell and convert said dc output current into an alternating current, and an inductor serving to connect the ac output from said inverter to a commercial power source.

Abstract: An inverter (100) receives a DC voltage and generates therefrom a square wave output signal. The inverter includes an output transformer (T3) and a saturable core transformer (T4). The saturable core transformer (T4) provides base current for a first transistor (Q3) and a second transistor (Q4). The first transistor (Q3) and the second transistor (Q4) alternatively turn on and off, causing a square wave to appear across the secondary winding of the output transformer (T3). The primary winding of the output transformer is coupled to the collectors of the first and second transistors via a pair of windings (L10, L11) magnetically coupled to the saturable transformer (T4). A pair of diodes (D4, D5) are provided to prevent the output leads of primary windings of the output transformer (T3) from dropping below ground potential.

Abstract: A low-pressure mercury vapor discharge lamp comprises a tubular bulb having an inside diameter of from 22 mm to 35 mm, an electrode-to-electrode distance of from 400 mm to 1,200 mm, and an inner surface coated with a phosphor. A rare gas including Kr and a mercury vapor source are sealed in the bulb, which is energized by an igniting device having a high-frequency power supply connected to a DC power supply for generating a substantially sinusoidal high-frequency output voltage, and a quiescent period generator connected to the high-frequency power supply and including a switch 17 turned on and off at least once during each half cycle to provide a quiescent period and thereby produce a substantially square wave high-frequency output voltage having rise and fall times of 2 .mu.s or less.

Abstract: A DC-DC converter includes first and second switches to be opened and closed at mutually exclusive times at a predetermined frequency. The first switch is connected to an inductor and a transformer primary winding so that a first current component from a DC input supply flows through it via the inductor. A second current component having a sinusoidal component flows through the first switch in response to discharge of energy stored in a resonant circuit coupled to the transformer. The second component begins approximately simultaneously with closure of the first switch. The second switch, when closed, is connected so that a bi-directional current component flows through it in response to energy stored in the inductor. The rectifier is connected between the secondary winding and the load so the secondary winding supplies substantial current to the load.

Abstract: An electrical converter for supplying electrical power to a load from a d.c. source and which includes semi-conductor switching means for converting a direct input current to an alternating current and output transformer means fed with the alternating current for changing the magnitude of the output voltage with respect to the input voltage, wherein the semiconductor means includes transistor means connected with a drive transformer means in a configuration which provides for switching in response to saturation of at least a part of the drive transformer means, and the drive transformer means includes a winding connected in the main current circuit of the transistor means in a configuration providing current feed-back to a drive branch of the circuit connected to a control electrode of the transistor means to increase the response of the transistor means to drive signals derived from the input current and effectively provide a forced D.C.

Abstract: A pulse width modulated D. C. to A. C. inverter circuit includes a first set of MOSFETS operated at a line frequency for transmitting high frequency clock pulses to a second set of MOSFETS for outputting a D. C. signal derived from a D. C. source. The inverter is part of an uninterruptable power supply and is operated upon the failure of the line A. C. to supply A. C. signals to a load. The high frequency clock signals are modulated on the A. C. output of the inverter. Two separate and distinct power switching channels are provided with each channel supplying one half of the sine wave outputted by the inverter.

Abstract: An electronic ballast-inverter circuit for powering one or more fluorescent lamps or the like includes two identical circuits operating at different DC offsets, each circuit including a tank circuit composed of a primary winding of the power transformer and a capacitor such that each tank circuit resonates at the same frequency, and including a switching transistor connected to each tank circuit. These two transistors are operative on alternate half cycles of the sine wave generated by the inverter, so as to obtain the push-pull operation needed by the inverter. Each circuit includes a base drive current source for each transistor that is controlled by the polarity of an additional primary winding of the power transformer. For improved efficiency, the circuit is designed to be operable from an unsmoothed DC voltage source.

Abstract: In many applications of electronic inverters, especially in applications involving inversion of relatively high levels of power, it would be desirable to use full-bridge inverters rather than half-bridge or regular parallel push-pull inverters.In its preferred embodiment, subject invention constitutes a self-oscillating inverter circuit based on a full-bridge configuration of four switching transistors. Positive feedback and avoidance of commutation overlaps are accomplished by using four non-coupled saturable current transformers--one such transformer for each transistor.By arranging for two of these saturable transformers to require fewer volt-seconds for saturation than do the other two transformers, coupled with the use of a shunt-connected inductor across the output, the inverter output voltage--rather than being a simple squarewave--is made to alternate between three magnitude levels: a maximum negative voltage level, a zero voltage level, and a maximum positive voltage level.

Abstract: A condenser microphone including an electrostatic transducer provided with at least one conductive vibrating plate and at least one fixed electrode arranged opposite the vibrating plate, and through which output voltages can be obtained in response to an acoustic input, and an impedance converter circuit connected to output terminals of electrostatic transducer, wherein said electrostatic transducer is arranged in such a way that two output voltages out of phase with respect to each other are obtained through its first and second output terminals, and said impedance converter circuit includes first and second field effect transistors of same conductivity channel type whose gates are connected to output terminals of electrostatic transducer, respectively, and whose drains are connected to a DC power supply, first and second impedance elements connected between gates of field effect transistors and ground to hold the DC potential of each gate at ground level, and an output circuit means for generating an output

Abstract: An induction heating arrangement adapted for energization by a pulsating power supply of relatively low frequency is provided, in which an induction heating coil is coupled to the power supply by a pair of power transistors arranged for push-pull operation. Alternately switching each of the power transistors into conduction causes current pulses of opposite direction to alternately flow in the coil. The transistors are arranged to switch at a frequency which is high relative to the frequency of the power supply and which varies directly with the instantaneous amplitude of the power supply voltage. The amplitude of the current pulses varies directly with the instantaneous amplitude of the power supply and the duration of the pulses varies inversely with amplitude of the power supply with the result that the amount of energy delivered to the coil by each current pulse is essentially uniform from pulse to pulse.

Abstract: A high efficiency push-pull inverter circuit employing a pair of relatively high power switching transistors is described. The switching on and off of the transistors is precisely controlled to minimize power losses due to common-mode conduction or due to transient conditions that occur in the process of turning a transistor on or off. Two current feed-back transformers are employed in the transistor base drives; one being saturable for providing a positive feed-back, and the other being non-saturable for providing a intermittently negative feed-back.

Abstract: A solid-state power generator or inverter for operating a load such as one or more gas discharge lamps from a DC or rectified AC power source includes two principal circuits, one being a drive circuit with pulse formation derived by negative feedback and the other being an inductively driven or dependent circuit with pulse formation by positive and negative feedback. The circuits operate in 180.degree. phase relationship. The circuits as disclosed are identical except for a capacitor in the first which is not present in the second. The circuits are coupled by a five-winding nonsaturable core transformer in which DC pulses passing through two primary windings induce in one secondary winding a sinusoidal EMF proportional to the product of the two primary currents and, in turn, proportional current flows in the load. Open circuit protection is also provided.

Abstract: A high efficiency push-pull inverter circuit employing a pair of relatively high power switching transistors is described. The switching on and off of the transistors is precisely controlled to minimize power losses due to common-mode conduction or due to transient conditions that occur in the process of turning a transistor on or off. Two current feed-back transformers are employed in the transistor base drives; one being saturable for providing a positive feedback, and the other being non-saturable for providing a subtractive feedback.

Abstract: A self-oscillating DC to DC converter which includes either two or four transistors, three transformers (a converting transformer, a driving transformer and a current transformer) and an inductance.The operating frequency of the converter is fixed by the saturation time of the driving transformer. The base currents of the transistors are mainly supplied by the current transformer so as to be in proportion to the collector currents of the transistors. The operating frequency of the converter is kept constant in spite of load fluctuations. The inductance which is connected in series between a winding of the converting transformer and a winding of the driving transformer. The inductance prevents the two or four transistors from being `on` simultaneously.

Abstract: A self-starting transformer-coupled FET multivibrator is constructed to avoid net dc flow in the primary winding of its transformer, driven push-pull by the multivibrator FET's.

Abstract: A d-c/d-c converter has two switching transistors connected in push-pull across respective primary halves of an output transformer working into a full-wave rectifier, these primary halves lying in parallel with the primary of a self-saturating feedback transformer whose secondary is split into halves respectively inserted in the emitter/base circuits of the two transistors. The primary of the feedback transformer is shunted by a protective network which comprises a capacitor in series with a rectifier bridge; the network may also include one or two thyristors fired in response to an excessive collector current drawn by the transistors.

Abstract: The invention relates to a d.c. to a.c. converter comprising two transistors (22, 25) and an output transformer (21). This converter also includes an auxiliary d.c. voltage source (43) and is provided with an auxiliary winding (40) of the transformer (21) which connects the base of one transistor (22) to the base of the other transistor (25).According to the invention, the combination of the auxiliary d.c. voltage source (43) and a control circuit of the two transistors (22, 25) comprises a current blocking means (44) such that the converter can be supplied with a pulsed d.c. voltage. Consequently, that converter can be operated from a low frequency a.c. voltage mains via an auxiliary full-wave rectifier (5 to 8), which does not need to have a high value smoothing capacitor.

Abstract: High efficiency push-pull inverters minimize undesirable energy losses usually resulting from simultaneous conduction and imperfect switching of the transistor switching means. In each of the disclosed circuits, a saturable inductor and a diode are connected in parallel and across the base-emitter junction of each transistor. Voltage on the base of each transistor causes its associated saturable inductor to saturate, and the saturated inductor then terminates the flow of base current and provides a path for rapid evacuation of the charge carriers stored in the transistor base-emitter junction in order to render the transistor rapidly non-conductive. Each diode provides a drain path for current continuing to flow through its associated saturable inductor after junction evacuation. A novel triggering means initiates oscillation of the inverters.