Abstract: An improved high efficiency push-pull inverter circuit employing a pair of switching transistors that are alternately triggered into conduction by a control circuit, for converting DC voltage into high frequency AC voltage. The control circuit includes a pair of saturable transformers that are non-coupled to each other and are each connected to the base of a respective transistor. The bases are isolated from ground potential by a capacitor, and significant reverse voltage signals are developed and alternately applied to the base of a conducting transistor for rapidly turning it off, thereby increasing device switching speed and overall efficiency of the circuit.

Abstract: The present invention relates to a lighting unit utilizing an energy efficient arc lamp as the main source of light supplemented by a standby filamentary lamp, the filament serving as a resistive ballast for the arc lamp during normal operation. The lighting unit is designed for functional similarity to an incandescent lamp, the filament providing immediate illumination when the lighting unit is first energized and continuing illumination until the arc lamp itself produces light. In accordance with the invention, if the arc lamp does not start within a predetermined period, the application of starting potentials produced through operation of a solid state switch and a high frequency step-up transformer is discontinued and the lighting unit rendered inactive. Exemplary means includes a positive temperature coefficient thermistor responsive to the temperature rise of the solid state switch.

Abstract: A spark ignition system utilizes a one transistor inverter including a transformer with a primary winding, controlled by the transistor and a feedback winding switching the transistor on and off. The core of the transformer saturates at a current less than that required to saturate the transistor. An inductor in series with the primary winding has an inductance greater than that of the primary winding when the latter is saturated but less than that of the primary winding when the latter is not saturated. The second winding is used to charge a capacitor which has a spark circuit across it.

Abstract: An electronic ballast circuit for a multiple gaseous lamp load includes a feedback rectifier circuit coupled to a high frequency inverter circuit and to a DC source. The high frequency inverter circuit is also coupled to the multiple gaseous load and a variation in an alterable impedance of the feedback rectifier circuit causes a variation in power applied to the multiple gaseous load and power provided by the DC source.

Abstract: This invention is a circuit to invert DC to AC for the operation of electroluminescent lamps. A primary winding of a transformer is in series with a power source and the input or output of the switching device. The output of the switching device is connected back to the power source. The secondary winding of the transformer is in series with an electroluminescent lamp and the controller side of the switching device. The secondary winding doubles as both the output to the electroluminescent lamp and the feedback winding to the controller side of the switching device. The electroluminescent lamp doubles both as the load and limiting impedance to the controller side of the switching device.

Abstract: A dc to ac inverter for operating a gaseous discharge lamp through pre-ignition, arc stabilization, warm-up and final run states is disclosed. The arrangement comprises a transformer and a pair of transistors connected for alternate conduction in a self-oscillating configuration in which turn off occurs at a predetermined flux level in each conduction period. The flux limit is used to preclude excess current drain during warm-up when the lamp resistance is at a minimum. A capacitor is provided, resonant at a harmonic of the inverter output waveform for producing the enhanced output voltage required for pre-ignition. The capacitor also helps to maintain a higher harmonic content during warm-up, enhancing the effective ballasting reactance during that period in relation to that during final run operation. A shift of the oscillating frequency of the inverter from pre-ignition to final run operation further enhances inverter operation.

Abstract: An electronic ballast for starting and operating gaseous discharge lamps from a low voltage d-c source which employs a regulated inverter providing controlled high ignition voltage, constant current warm-up and constant wattage operation for one or more lamps.

Abstract: A static inverter employing an inductor and an electrical gain element for intermittent assymetric energization of the inductor from a dc source is described. Reliable intermittent operation of the gain element, typically a power transistor, is achieved by use of three feedback windings which in response to saturation of a branch of the core of the inductor but before full core saturation, discontinue regenerative feedback and then apply degenerative feedback. This turn off mechanism protects the transistor from high current stresses. Passive means are provided such as a capacitor for momentarily storing the energy or diode means for coupling the energy back to the source or to the load to protect the transistor from the high voltage surge and the energy release when current flow in the inductor is interrupted. Energy stored in the capacitor may be used for transistor commutation.

Abstract: A full wave bridge inverter includes four switch arms, each including N bipolar, parallel transistor switching elements. During a first interval, emitter-collector paths of all transistors in the first and second arms are forward biased so current flows in a first direction from a DC source through a bridge diagonal. During a second interval, emitter-collector paths of all transistors of the third and fourth arms are forward biased so current flows from the source through the diagonal in a second direction. The transistors have a tendency to be activated into the conducting and cut-off conditions at different times, and different transistors have a tendency to conduct differing amounts of current while forward biased. To overcome these tendencies, there are 2N.sup.2 transformers, each including first and second windings having like numbers of turns.

Abstract: An electronic ballast circuit includes a direct drive high frequency inverter circuit with a tuned output circuit and a drive circuit dependent upon current flow in a load circuit. The high frequency inverter circuit is coupled to a DC potential source which is derived from a pulsed DC potential source by way of a charge storage and charge isolating circuit. An oscillator provides a starting capability for the high frequency inverter circuit and is essentially removed from the active circuitry upon energization of the high frequency inverter circuit.

Abstract: A direct drive electronic ballast circuit suitable for a fluorescent lamp load includes a high frequency oscillator inverter circuit having a tuned output circuit coupled to a load and to a drive circuit series connected to the load and dependent upon current flow therein. The high frequency oscillator inverter circuit is also coupled to a pulsed DC potential source which is shunted by a charge storage and isolating circuit energized by a feedback rectifier circuit which supplies energy whenever the potential from the pulsed DC potential source decreases below a given reference level. A relaxation type oscillator is coupled to the high frequency oscillator inverter circuit and provides a starting capability therefore.

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.

Abstract: A free-running inverter preventing excessive current spikes comprises a transformer and a switch means for alternately connecting, and then disconnecting, a DC voltage to a transformer primary winding which encloses a parallel combination of a saturating magnetic core and a non-saturating magnetic core. A transformer feedback winding enclosing only the saturating core drives the switch means during and between switch states. Switching between states is accomplished prior to saturation of the composite core.

Abstract: A spark plug igniter with an auxiliary power source, in which the auxiliary power source is a DC-DC converter including a feedback loop. A high voltage induced in a secondary winding of an ignition coil and a DC voltage generated by the converter are additionally supplied in the same polarity to a spark discharge gap. The feedback loop of the DC-DC converter comprises a feedback winding, a rectifier connected to the feedback winding through a reactance element, and means for connecting the DC output of the rectifier in series to the DC power source of the converter in the same polarity.

Abstract: A system for operating gas discharge lamps at high frequency from a high voltage supply, typically 115 V AC with a 160 watt, 25,000 Hz output. The system provides efficient conversion, having the capability of driving any number of lamps up to maximum wattage, inherent open-cirucit and short circuit protection, and higher efficacy from the lamps. Filament power may or may not be used. Filament power is not necessary under conditions when the lamps are forced into a glow discharge to charge each cycle through the use of a tuned resonant circuit. An unsaturated inverter provides fast cut-off times. Dimming capabilities may be provided.

Abstract: A highly efficient tuned oscillator ballast circuit especially suitable for a flourescent lamp load includes an oscillator circuit coupled to a pulsed DC potential source and having a tuned output circuit coupled to a load circuit, to a drive circuit for the oscillator which is dependent upon current flow in the load circuit and to a rectifier and charge storage and isolation and applying network coupled to the pulsed DC potential source and providing energy thereto whenever the potential decreases below a given reference level. A transient compensating circuit to protect the oscillator components from initial or "start-up" transients is also included.

Abstract: A high power factor conversion circuit suitable as a ballast circuit for lamps includes a full-wave rectifier coupled to an AC potential source and providing a pulsating DC potential. A high frequency inverter is coupled to a load circuit and to a feedback rectifier circuit supplying a rectified high frequency potential to an energy storage feedback circuit which provides energy in a manner to inhibit a decline in the pulsating DC potential thereby providing a substantially uniform DC potential to the high frequency inverter.

Abstract: A full bridge inverter includes four bipolar transistors of like conductivity type, connected in a bridge circuit including an apex to which a load is connected. During a first time interval, emitter collector paths of a first pair of transistors are connected betwen a DC source and the apex so that current flows in a first direction through the apex while the transistors are forward biased. The emitter collector paths of a second pair of transistors are connected with the source and the apex so that current flows in a second direction through the apex during a second interval while the transistors of the second pair are forward biased. A first transformer has first and second windings respectively connected in series with the emitters of the transistors of the first pair, such that voltages at the emitters of the transistors of the first pair have a tendency to vary in the same direction.

Abstract: A synchronization circuit for a free-running push-pull inverter in which the frequency is determined by a saturable transformer in the feedback loop. Synchronization is achieved by momentarily short-circuiting the inputs to the two switching transistors together to initiate the switching cycle.

Abstract: This invention relates to an improved small-sized electric flash device wherein transformers of its DC-DC converter circuit for producing a high voltage comprises printed coil or coils thereby efficiently reducing their volume and sufficiently flattering their shape, so that, together with miniaturized circuit parts and printed circuit substrate, highly integrated, hence compact photographic flash device is obtainable.

Abstract: A variable frequency ac source drives a gas discharge lamp connected as a damping element in an otherwise high Q L-C circuit. Commutation of the ac source voltage is initiated as the instantaneous current drawn from the source equals a predetermined reference current level. Prior to lamp ignition the ac source drives the L-C circuit at resonance causing a voltage buildup which initiates an ignition. After ignition the source limits lamp current to provide a ballasting function.

Abstract: A magnetically coupled two transistor multivibrator for use with power supplies. In addition to the usual collector driven output transformer, an auxiliary transformer having its secondary winding in series with the transistor base drive circuits is employed. The auxiliary transformer has primary windings powered by emitter current. Provision is also made for feedback from the main output transformer so that the secondary base drive windings can be powered from either emitter or collector currents. Electronic means are employed to isolate the output transformer from the base drive transformer upon the occurrence of a short circuit in the load, thus permitting the emitter windings to take over the function of supplying feedback and maintaining oscillations.

Abstract: A static inverter comprises switching transistors, resistors connecting the bases of the transistors with a junction point connected to a source of DC voltage. The bases of the transistor are inductively coupled by inductance means coupled with coils connecting the collectors of the transistors to the junction. The inverter is adapted to operate a plurality of fluorescent lamps. Each lamp is in series with the secondary of a transformer whose primary is connected across the collectors of the transistors.

Abstract: A fluorescent lamp ballast circuit includes a tuned oscillator coupled to a pulsed DC potential source and to a transformer having a first winding directly connected to the oscillator and in series connection with a capacitor to form a series resonant circuit. A second winding of the transformer inductively couples the first winding of the transformer to the oscillator, a third winding inductively couples a load across the capacitor of the series resonant circuit, and a fourth winding is inductively coupled to the first winding of the transformer and clamps the DC potential source to a given potential level. Also, protection for open circuits, short circuits, and temperature change due to changed ambient conditions or increased current flow is provided.

Abstract: A high frequency transistor ballast is utilized to drive flourescent lamps. The electrical system of the ballast consists of a central rectifying and control panel and a high frequency inverter. There is also provided a low energy switch in the high frequency inverter system controlling the operation of the high frequency transistor ballast.

Abstract: A magnetostrictive mechanical, variable frequency stress transducer is disclosed in which the frequency of the output signal is proportional to the applied stress. This device consists of a magnetic stress actuating member, to which the stress is applied, and a transistor-magnetic oscillator constructed so the stress sensitive magnetic characteristic of the stress actuating member is the principal frequency determining element of the oscillator.

Abstract: A transistor inverter includes at least a pair of switching transistors, a transformer with primary and secondary windings, a DC voltage source with a pair of output terminals and a voltage reference terminal, and a rectifying circuit connected to the secondary winding of the transformer. A collector electrode of one of the switching transistors is insulated from a chassis by an insulation means comprising a first insulating layer, a conductive layer such as a heat sink and a second insulating layer. The conductive layer is electrically connected to the voltage reference terminal of the DC voltage source so as not to produce an undesirable radiation through the chassis.

Abstract: A transistor inverter includes a pair of switching transistors each having base, emitter and collector electrodes, each of the collector and emitter circuits of which is connected between a DC voltage source through a primary winding of an output transformer, respectively, the secondary winding of which is connected to a rectifying circuit so as to produce a DC output voltage at its output. The transistor inverter also includes an input transformer with a saturable core and voltage feedback and current feedback circuits. The current feedback circuit has another transformer which controls the amount of current feedback, and the winding ratio of the primary and secondary windings is determined in connection with the current amplification factor of said first and second switching transistors in order to improve a switching speed of the switching transistors.

Abstract: An asymmetrical transistorized multivibrator with inductive timing circuits, comprising a flip-flop built around two transistors and resistors, a timing saturable reactor having a tap from a portion of winding turns and two diodes, the first of said diodes being connected between the lead of the reactor's winding and the collector of the second transistor, the second diode being connected in opposition to the first diode, between the collector of the second transistor and the lead of the winding, whereas an individual load resistor is connected to the collector circuit of each transistor.

Abstract: A dynamic temperature compensating circuit is disclosed for driving the bs of a first and a second transistor connected in the common-emitter configuration, having collector-emitter paths of the two transistors connected together in a current loop. The circuit employs diodes arranged in parallel in the base-emitter drive circuit of each transistor, to clamp the transistors on or off at appropriate times. The diodes and transistors are composed of the same type of semi-conductor material so that their respective forward bias potentials maintain equal magnitudes over a range of temperatures. The circuit has particular application in D.C.-A.C. and D.C.--D.C. converters.

Abstract: High voltage arrangement for an image intensifier with automatic brightness control, comprising a transistor oscillator including a transformer having a feedback winding, a voltage multiplier connected to the transformer and a control circuit, the control circuit including an auxiliary winding of said transformer connected in series with said feedback winding, and a control transistor connected as current source, the control transistor having its collector-emitter circuit connected through one or more diodes to said auxiliary winding.

Abstract: A submarine power package converts direct current electrical energy to alnating current energy and is adapted to function while exposed to the high pressures of the deep ocean. A diode protection circuit and special semiconductor mounting arrangement makes this performance possible without the use of a pressure housing.

Abstract: A power source for operating gas discharge lamps and other loads at high frequency, typically utilizing a 115 volt ac source rectified to provide a 150 volt dc input and providing a 20,000 hertz output. An inverter with a transistor current control for protection against transistor damage under open circuit, starting and no-load conditions, with low power consumption under no-load and with dimming capability. An inverter with a detector circuit connected across the feedback winding or an additional control winding for developing a control signal varying as a function of the feedback winding output, and a zener diode or other device for connecting the control signal to the base of the transistor in current controlling relation when the control signal exceeds a predetermined value.

Abstract: A transformer designed to operate with a pair of power switching transistors in a d.c. to a.c. inverter is described. The transformer has an assembled core whose closed magnetic path is branched. A flux steering winding is used to ensure the prior saturation of a first branch associated with a regenerative feedback winding. Prior saturation of this branch reduces the forward drive on the switching transistors prior to full core saturation and avoids the consequent switching stresses on the transistors. The cores of the transformer are made from parts which abut at the branches so that both preformed power and preformed control windings may be used in assembling the transformer. The transformer may be assembled from conventional core configurations, and is thus of relatively low cost. A core arrangement is also disclosed in which the cross-section of the individual branches of the core may be adjusted.

Abstract: A method and apparatus of lighting a cold cathode electric gas discharge lamp in which the lamp is connected across the secondary winding of a voltage step-up transformer, and the primary winding of the transformer is energized with a chopped D.C. voltage having a frequency of at least 12 kHz and a voltage which provides an output voltage from the secondary winding having an R.M.S. value no greater than 700 volts.

Abstract: A static inverter is disclosed for d.c. to a.c. conversion comprising a pair of switching semiconductor devices and a power transformer having primary, secondary and control windings associated with a double apertured linear magnetic core. Each aperture partitions the core cross section in a localized region into two branches. The primary and secondary power windings encircle the full core, which has a closed magnetic path, while the control windings are associated with only a branch. Means are provided to cause one branch to saturate before the other branch and before full core saturation. Saturation of one branch is used to reduce the regenerative feedback and increase the degenerative feedback to provide an advance turn off, allowing charge stored in the switching device to dissipate prior to the end of each conduction period. This mode of the feedback control avoids full core saturation and avoids overstressing the switching devices that full core saturation would produce.

Abstract: A pulse-firing power oscillator has an iron core with a primary winding on the core and as many secondary windings as there are firing pulses to be sequentially produced in a series of pulses, with a half-wave rectifier in series with each secondary winding. A symmetrical circuit comprising back-to-back transistors is connected across the primary winding in such a manner that the base bias voltage of a transistor connected to one end of the primary winding is derived from the other end of the primary winding. A DC voltage is imposed between a center-tap on the primary winding and the common connection between the transistors which is furthest away from the center-tap -- i.e., further away from the center-tap than the base of each of the biased transistors. The oscillator is self starting, and when it is free running its frequency is voltage dependent, although broadly determined by the design of the pulse transformer including the cross-section of the core and the number of primary turns thereon.

Abstract: Magnetic signal mixing amplifier comprises a saturable core having a rectangular magnetization characteristic, at least one D.C. input winding, and a D.C. driven oscillator connected to receive the output, said amplifier being supplied with an asymmetrical waveform so that a difference between the mean values of the positive and negative halfwaves of the oscillatory output results.

Abstract: In a microwave energy generating system, a combination of a magnetron which generates microwave energy and an inverter which converts DC voltage to high frequency AC voltage are employed. The magnetron includes a heater-cathode and an anode. The inverter includes a transformer having a gapped ferrite core, a center tapped primary winding which divides the primary into two portions, and at least a first high voltage secondary winding and a second low voltage secondary winding for the magnetron heater, and means for switching current through each winding half alternately at a periodic high frequency rate, substantially above 60 Hz., to produce a high frequency magnetic field in said ferrite core, and means, including inductor means, are provided for providing DC current into said primary winding at said center tap.

Abstract: A regulated switched mode power supply comprising a first rectifier adapted to be coupled to a first source of alternating current potential to produce a first source of direct current potential, an oscillator coupled to the first source of direct current potential to produce a second source of alternating current and a second rectifier coupled to the oscillator to produce a second source of direct current potential. The second source of direct current potential being maintained relatively constant with a predetermined range of variations of magnitude of the first alternating current potential by controlling a first pulse width of the second alternating current potential in response to a correction signal. The correction signal is derived by comparing a reference potential and a third direct current potential which is developed across a storage capacitor, the third direct current potential being a function of the first pulse width and the magnitude of the first alternating current potential.

Abstract: An electrical inverter circuit for converting d.c. electrical input into an a.c. electrical output involving the control of active switch elements in the primary of an output transformer circuit by, in part, providing a further controllable active element in circuit with the active element switches such that the primary winding current also flows therethrough. Synchronous control means are provided for synchronously controlling this further active element so as to increase its electrical impedance during at least a portion of each switching transition of the active element switch means so as to further aid and promote the rapid and efficient transitioning of the active element switches. Various alternative circuits are shown for this and for detecting the switch point as a function of primary transformer winding current and for further controlling the transition of the active switches in combination with the increased electrical impedance of the further controllable active element in circuit therewith.