Abstract: An DC/AC converter for supplying two gas discharge lamps, includes a double bridge configuration of four switches and a controller. The controller controls the conducting periods of the switches with a duty cycle which is variable. By control of the conducting periods of the switches, a proper control of the energy supplied to the lamps is obtained.

Abstract: An illuminating device according to an embodiment of the present invention includes a dielectric barrier discharge type low pressure discharge lamp 1 composed of a tubular glass lamp vessel 10, in which mercury and rare gas are enclosed, a first and a second electrode 21,26, which are made of electrically conductive layer, are provided on an outer surface of both ends of the tubular glass lamp vessel 10 and a high frequency power source of a floating output type 81,82, which supplies a sine wave voltage between the first and the second electrodes of the dielectric barrier discharge type low pressure discharge lamp 1 having a neutral point of the sine wave voltage being grounded, and which supplies a frequency in a range from 40 kHz to 100 kHz.

Abstract: A method of color mixing with arc stability and arc straightening of HID lamps operated at high frequencies which modulates a duty cycle of a half bridge configured resonant inverter at a frequency which is substantially one-half the frequency of a second longitudinal acoustic mode of the HID lamp. The method also sweeps the switching frequency in a high frequency range of such resonant inverter. The duty cycle modulation effectuates power modulation to create a fixed frequency power component which is substantially equal to the frequency of the second longitudinal acoustic mode. The sweeping switching frequency of the half bridge configured resonant inverter drives the HID lamp in a manner which effectuates arc stability and arc straightening.

Abstract: This invention provides a magnetron high frequency device which includes: a filtering inductor coupled to a positive end of a direct current power supply; a central tap transformer having a central tap end, a first end and a second end; a filtering capacitor; a first switch which is connected in series to the second end of the central tap transformer and connected to a negative end of the direct current power supply; an in-series circuit having a second switch and a second capacitor and coupled to the central tap transformer; a first capacitor connected in-series with the central tap transformer and connected in parallel with the first switch; a rectifying device coupled to a secondary winding of the central tap transformer; and a magnetron coupled to the rectifying device. The first capacitor, the second capacitor and the central tap transformer forms a resonant circuit.

Abstract: In a discharge-lamp lighting circuit for turning on a plurality of discharge lamps, starting circuits 8 for supplying starting pulses to the respective discharge lamps are provided. Each starting circuit 8 has transformers T1 and T2 equal in number to the discharge lamps and each of the transformers has a primary and a secondary winding. The discharge lamps 6—1 and 6—2 are connected to the respective secondary windings T1s and T2s. Capacitors C1 and C2 are connected to the respective primary windings T1p and T2p of the transformers and one switch element SW is provided in a circuit including the primary windings and the capacitors. When the accumulated charge in each capacitor is discharged via the primary winding of the transformer as the switch element SW conducts, the starting pulse is generated and supplied to each discharge lamp via the secondary winding of each transformer.

Abstract: In a high frequency oscillator system a series oscillator circuit includes a load coil inductively coupled with a plasma generator. A capacitance is in series with the coil between the drain and source terminals of a transistor. A capacitive or inductive feedback responsive to the oscillation is connected to the gate terminal of the transistor. In another embodiment two sections of a series circuit are connected by the load coil, each section including a separate transistor. A first capacitance is connected between the coil and the first transistor drain, and a second capacitance is connected between the coil and the second transistor drain. A first capacitive feedback is connected between the second section and the first transistor gate, and a second capactive feedback is connected between the first section and the second transistor gate.

Abstract: An electronic ballast is powered from a constant-magnitude DC supply voltage and provides a high-magnitude high-frequency voltage at a ballast output across which are connected two lamp-ballast series-combinations, each consisting of an instant-start fluorescent lamp series-connected with a ballasting capacitor. An auxiliary capacitor is connected in series with the ballast output, thereby having the total ballast output current flowing through it and causing an auxiliary high-frequency voltage to develop across its terminals. The constant-magnitude DC supply voltage is provided via a series-combination of a power-line-connected rectifier delivering an unfiltered full-wave-rectified power line voltage across a pair of rectifier DC terminals and an auxiliary DC power supply delivering an auxiliary DC voltage across a pair of auxiliary DC terminals from which, under open circuit condition, is available a DC voltage of magnitude equal to the peak magnitude of the full-wave-rectified power line voltage.

Abstract: An electronic, externally controlled ballast has a control oscillator which feeds a fluorescent lamp via an invertor bridge and a resonant circuit. To keep the voltage constant, there are derived from the lamp AC voltage charge packets whose size (and/or phase angle) characterizes the size of the lamp AC voltage. The charge packets are conducted onto a frequency-determining capacitor of the oscillator, which is designed as a sweep oscillator, voltage control thereby being achieved. The ballast provides for reliable operation of gas-discharge lamps. Its design is robust and yet simple, avoids undesired hunting and delivers a good degree of voltage stability.

Abstract: A circuit arrangement for igniting and operating a high-pressure discharge lamp is provided with a switching device, inductive device and a rectifier which together form a Buck converter, connected to input terminals for connection to a supply source and output terminals for connection of the lamp. The lamp is supplied with a current through periodic switching of the switching device alternatively into a conducting and a non-conducting state by means of a switch-on and switch-off signal, respectively. The inductive device includes a primary and a secondary winding with the secondary winding forming part of an integration network for generating the switch-off signal. The secondary winding also forms part of a voltage divider network for generating the switch-on signal. A very simple circuit arrangement is thereby achieved.

Abstract: An electronic ballasting circuit provides high efficiency ballasting for most common types of fluorescent lamps. The circuit consists of a half-bridge inverter providing a substantially squarewave voltage across a series-combination of an inductor and a capacitor. The fluorescent lamp is connected in parallel circuit with the capacitor in such a way that the current flowing through the capacitor also flows through the lamp cathodes, thereby providing continuous low voltage heating therefor. The values of inductance and capacitance are so chosen that the series-combination has a natural resonance frequency that is substantially equal to or lower than the lowest frequency component present in the squarewave voltage.

Abstract: A frequency-modulated converter with a series-parallel resonance, particularly for driving any ohmic or inductive load, including gas discharge tubes, wherein a commutating voltage switch in the form of a transistor is provided and is connected in series between a negative electrode of a direct current voltage source and a first terminal of an inductor, and a pulse generator circuit is provided between the voltage source and the transistor's control electrode and the inductor's second terminal is connected to the primary winding of a transformer.A first capacitor and rectifier diode are also provided in a first and second parallel branch respectively between the transistor's charge receiving and charge emitting electrodes, and a second capacitor is provided across the voltage source's electrodes, and a smoothing capacitance is provided for the voltage source, the second capacitor being connected in series with the inductor via the diode.

Abstract: An inverter-type electronic ballast for a gas discharge lamp is powered by a DC supply voltage provided from a rectifier-filter combination connected with an ordinary electric utility power line. The absolute magnitude of the DC supply voltage is higher than the peak absolute magnitude of the power line voltage. The ballast includes an inverter circuit operative to provide an inverter output voltage of special trapezoidal-like waveshape; which output voltage is applied to a series-resonant combination of an inductor and a capacitor. The gas discharge lamp is connected in parallel with the capacitor. The inverter is driven by a voltage of special waveshape and controllable frequency. By controlling the frequency, the magnitude of the current supplied to the gas discharge lamp can be adjusted, thereby correspondingly adjusting the amount of light produced by the lamp.

Abstract: A half-bridge inverter is powered from a constant-magnitude DC supply voltage and provides at the inverter's output a first AC output voltage that is describable as a modified squarewave voltage. This first AC voltage is applied across a series-combination of an inductor and a capacitor, the junction between which is clamped to the DC supply voltage. As a result, a second AC voltage gets established across the capacitor; which second AC voltage is also describable as being a modified squarewave voltage. However, the phasing of the second AC voltage is delayed by approximately 90 degrees with respect to the first AC voltage; which results in the voltage across the inductor being of approximately sinusoidal waveform. A fluorescent lamp is connected in series with a ballast capacitor; and the lamp-capacitor series combination is connected across the inductor, thereby resulting in a nearly sinusoidal current being provided to the fluorescent lamp.

Abstract: A relatively high efficiency, relatively light weight, relatively small electronic ballast or AC power controller for use in aircraft and elsewhere for controlling a fluorescent lamp load or other load includes an EMI filter, a multi-purpose transformer, a power conversion stage and a control circuitry stage. The ballast or controller operates to increase or decrease the voltage of the incoming sine wave AC voltage through a charging path for an energy storage inductor choke cooperating with an energy storage capacitor wherein the charging path for the capacitor is different from the discharge path of the capacitor to isolate the load from the charging of the capacitor and thus to provide an output to the load which is independent of the charging path and which is out of phase with the incoming waveform.

Abstract: A pre-converter is connected with AC power line voltage and provides DC voltage across a pair of DC terminals. A current-limiting inductor, a self-oscillating parallel-resonant inverter, and a periodically activated FET switch are series-connected with one another across the DC terminals. The inverter provides a high-frequency (e.g., 20-30 kHz) substantially sinusoidal output voltage across its output terminals. Each of plural rapid-start fluorescent lamps is connected across the output terminals by way of a current-limiting capacitor. The magnitude of the resulting lamp current depends on the RMS magnitude of the output voltage. In turn, for a given load condition, this RMS magnitude depends on the average magnitude of the unidirectional current drawn by the inverter from the DC terminals; which average magnitude is determined by the ON/OFF duty-cycle of the FET switch. The FET switch is turned ON/OFF at twice the frequency of the inverter's output voltage.

Abstract: The present invention describes a method and apparatus for a swept frequency switching gas discharge tube supply which produces a "crawling effect" in gas discharge tubes containing neon, argon or mercury gases or other gases and which has a means for eliminating the "bubble effect". To produce the "crawling effect", the driving frequency of the switching supply is swept from a higher frequency to a lower frequency thereby causing the excitation point to move from the electrodes on both ends of the dual electrode gas discharge tube to the center of the gas discharge tube. By varying the base switching frequency of the supply, the bubble effect which plagues some displays can be eliminated.

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

Abstract: A special fluorescent lamp is provided with its own built-in cathode heating means and is operable to be properly ballasted by way of a light-weight two-wire power cord coming from a special power plug that comprises a built-in high-frequency ballasting means. This special power plug is suitable for being plugged into, held by, and powered by any ordinary household electric power receptacle. The combination of the special fluorescent lamp and the special power plug constitutes a product similar to the so-called bright-stick marketed by General Electric.

Abstract: The present invention describes a method and apparatus for a high frequency switching gas discharge tube supply which suppresses or eliminates the "bubble effect" in gas discharge tubes containing neon or argon-mercury gas or other gases and which eliminates the migration of mercury or other migratory gases toward one electrode over time. To prevent mercury migration to one electrode over time within an argon-mercury gas discharge tube, a line frequency bias voltage is induced on the high frequency, high excitation voltage resulting in a gas discharge tube display which is uniform in intensity of light over the length of the tube.

Abstract: A relatively high efficiency, relatively light weight, relatively small electronic ballast or AC power controller for use in aircraft and elsewhere for controlling a fluorescent lamp load or other load includes an EMI filter, a multi-purpose transformer, a power conversion stage and a control circuitry stage. The ballast or controller operates to increase or decrease the voltage of the incoming sine wave AC voltage through a charging path for an energy storage inductor choke cooperating with an energy storage capacitor wherein the charging path for the capacitor is different from the discharge path of the capacitor to isolate the load from the charging of the capacitor and thus to provide an output to the load which is independent of the charging path and which is out of phase with the incoming waveform.

Abstract: A flashing light warning apparatus, which includes a voltage source (U), a main gate transformer (HW), a flash tube (R), an ignition device (Z), at least one storage condenser (K), and an electrical switching device (S), can be switched to provide light energy for daytime flashes and nighttime flashes in an uncomplicated, cost effective system which produces dependable light flashes. The night flashes have a light energy such that they can be seen from afar only with night vision apparatus. When the switching device turns off voltage production of the main gate transformer or further transmission of voltage from the at least one storage condenser, the ignition device is coupled to an auxiliary gate transformer (ZW) for carrying out light flash production by means of high frequency ignition voltage produced by the ignition device.

Abstract: A ballast circuit includes a load circuit. A reservoir capacitor is effective to supply charge to the load circuit. A capacitive charge pump circuit is effective to transfer charge from a charge pump capacitive circuit to the load circuit and to the reservoir capacitor. The load circuit includes the primary winding of a transformer. A secondary winding of this transformer is for connection across a discharge lamp. In operation of the ballast circuit, the primary winding of the transformer drives the capacitive charge pump circuit.

Abstract: A light source having two potential terminals, a transformer coil having a primary incorporating two windings and a secondary transistor, the first potential terminal being connected to the first winding of the primary, which is connected to the base of the transistor, the collector of which is connected to the second winding of the second terminal, a load capacitor connecting the second winding to the second terminal, a potentiometer connecting the first terminal to the capacitor at the common point between the capacitor and the second winding, a sealed chamber incorporating two electrodes containing a gas, these two electrodes being connected to the winding of the secondary. The invention is advantageously applied in illumination of any type, in industry, advertising, domestic equipment, etc.

Abstract: A power supply circuit for a magnetron adapted to supply microwave energy to an electrodeless discharge bulb is disclosed. The circuit includes a rectifier coupled across a commerical AC voltage source, a filter for smoothing the output of the rectifier, an inverter for converting the DC voltage supplied from the filter into a high frequency AC voltage, a step-up transformer for stepping up the high frequency AC voltage outputted from the inverter, and a rectifier which rectifies the high voltage AC output of the transformer into a unidirectional voltage which is supplied to the magnetron. The inverter switching is controlled by a pulse width modulation control circuit to maintain the magnetron output power at a predetermined level.

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: In a power-line-operated power-factor-corrected electronic ballast, a pair of series-connected fluorescent lamps is powered via a tuned L-C circuit that is series-excited by the rectangular-wave 33 kHz voltage output of a half-bridge inverter and parallel-loaded by the fluorescent lamps. Power factor correction is attained via two energy-storing capacitors charged during periods when the instantaneous absolute magnitude of the power line voltage exceeds half of its peak absolute magnitude and discharged when it fails to exceed half of this peak absolute magnitude. As a result, a so-called valley-filled DC voltage is provided to the inverter; which results in the inverter's rectangular-wave output voltage being about 50% amplitude-modulated. In spite of this high degree of amplitude-modulation, the resulting lamp current crest factor is only about 1.8.

Abstract: The inverter circuitry requires minimal operating input power, is power factor correcting and may, if desired, include a dimming circuit. The circuitry further includes a runaway protection circuit which is activated upon sensing of a no load condition to place the inverter circuitry in a standby mode of operation.

Abstract: A fluorescent lamp lighting apparatus comprising a DC power source, a pair of field-effect transistors which are connected in series to each other, in which drains and sources of these transistors are connected in series to each other, whereas gates are connected to an oscillator, a pair of voltage-dividing capacitors which are connected in parallel to the DC power source, and an inverter circuit having an insulative leakage transformer whose primary coil is connected to a contact between these field-effect transistors and also to the other contact between those capacitors. One-end of filaments of a fluorescent lamp are connected to both ends of the secondary coil of the leakage transformer, whereas a startup capacitor is connected between the other ends of the filaments.

Abstract: A power supply circuit for a magnetron adapted to supply microwave energy to an electrodeless discharge bulb is disclosed. The circuit includes a rectifier coupled across a commercial AC voltage source, a filter for smoothing the output of the rectifier, an inverter for converting the DC voltage supplied from the filter into a high frequency AC voltage, a step-up transformer for stepping up the high frequency AC voltage outputted from the inverter, and a rectifier which rectifies the high voltage AC output of the transformer into a unidirectional voltage which is supplied to the magnetron. The inverter switching is controlled by a pulse width modulation control circuit to maintain the magnetron output power at a predetermined level.

Abstract: A fluorescent lamp system utilizes boost power factor correction. The fluorescent lamp system includes a power source, a reference voltage and a fluorescent lamp. A resonant circuit supplies power to the fluorescent lamp. A first capacitor is connected between a first end of the resonant circuit and the reference voltage. A second capacitor is connected between the first end of the resonant circuit and the power source. A first switch is connected between a second end of the resonant circuit and the reference voltage. A second switch is connected between the second end of the resonant circuit and the power source. A control module operates the first switch and the second switch so that the resonant circuit operates at near resonant frequency. The control module is integrated on a single integrated circuit. The first switch and the second switch may be also integrated on the single integrated circuit.

Abstract: An improved power supply for one or more electric discharge lamps includes a high frequency oscillator-inverter circuit coupled to the output of a full-wave rectifier circuit via a transformer primary winding (25). The rectifier circuit is energized from a low frequency source of AC voltage. The oscillator-inverter circuit supplies high frequency oscillations to the lamp via a frequency-dependent ballast coupling circuit. A regenerative power supply is coupled to the transformer primary winding by means of a secondary winding (62) of the transformer thereby to charge a capacitor (49) operative as a switchable auxiliary supply voltage for the oscillator-inverter circuit. Improved start-up operation is achieved by winding the transformer (25, 62) so as to provide a polarity inversion for the supply of electric energy to the regenerative power supply.

Abstract: A circuit is disclosed which is capable of positively shifting a gas discharge lamp from its off-state to its on-state without emitting light flashes and further positively maintains the gas discharge lamp in its on-state when first ignited. The circuit contains an oscillator device which generates and supplies an oscillator signal of a specific oscillator frequency from two output terminals of the oscillator device. It also contains a current limiting device an a parallel-resonance circuit comprising a capacitor and an inductor. The parallel resonance circuit has a frequency of resonance substantially identical to the oscillator frequency. The current limiting device and parallel-resonance circuit are connected in a series configuration across the output terminals of the oscillator device. Further, the gas discharge lamp is connected across or in parallel with the parallel-resonance circuit.

Abstract: A power supply circuit for a magnetron adapted to supply microwave energy to an electrodeless discharge bulb is disclosed. The circuit comprises a rectifier coupled across a commercial AC voltage source, a filter for smoothing the output of the rectifier, an inverter for converting the DC voltage supplied from the filter into a high frequency AC voltage, a step-up transformer for stepping up the high frequency AC voltage outputted from the inverter, and a rectifier which rectifies the high voltage AC output of the transformer into a unidirectional voltage which is supplied to the magnetron. The inverter switching is controlled by a pulse width modulation control circuit to maintain the magnetron output power at a predetermined level.

Abstract: An ignition system of AC continuous discharge type is disclosed which comprises a switching circuit for supplying the primary current of an ignition coil alternately in two directions and which is applicable to the internal combustion engine, for example. The rise of the primary current is slowed by an inductance device and the energy stored in the inductance device is absorbed into a capacitor.

Abstract: The present invention uses a variable frequency oscillator to drive a primary resonant converter output transformer circuit for exciting gas discharge tubes. The combination of the impedance of the resonant conversion circuit along with the impedance of the driven gas discharge tube taken in combination with the frequency of the variable oscillator will determine the output voltage of the circuit. By varying the frequency of the oscillator, the optimal output voltage and hence the optimal brightness of the gas discharge tube may be selected. At the optimal output voltage, the frequency of the switching supply may create an undesirable or desirable "bubble effect" in the gas discharge tube. An optional secondary frequency may be combined with the frequency of the variable frequency oscillator to create or eliminate the bubble effect according to the esthetic desires of the user.

Abstract: A neon tube lighting device comprises a resonance circuit, formed by a capacitor and the primary winding of a leakage transformer, which is connected across a DC power supply via a switching element, the ON-OFF operation of which is controlled by the output signal of a signal generator. The output signal provided by the signal generator has a constant frequency substantially equal to the resonance frequency of the resonance circuit. A neon tube is connected to the secondary winding of the leakage transformer.

Abstract: A high-pressure sodium discharge lamp comprising a discharge vessel (3) provided with an external auxiliary electrode (11) and a built-in electric starting circuit including an electric circuit comprising a transformer winding (35a), a capacitor (33) and a semiconductor switching element (34). The circuit is connected in series with a resistor (32) electrically parallel to the discharge vessel (3) and with the transformer (35) electrically connected to the external auxiliary electrode (11). The semiconductor switching element (34) is an uncontrolled voltage-dependent breakdown element of the thyristor type having a breakdown current smaller than 1 mA at a breakdown time shorter than 10 .mu.s. The resultant lamp starts very reliably and its build-in starter dissipates only a very low power.

Abstract: A current fed high frequency oscillator-inverter ballast circuit includes a parallel resonant tank circuit for driving a pair of series connected discharge lamps via a series ballast capacitor. A regenerative power supply switches on when a fluctuating main DC supply voltage drops below a given level thereby providing a constant level auxiliary DC supply voltage to the oscillator inverter to maintain oscillation and lamp operation. When the main DC supply voltage exceeds said given level, the regenerative power supply switches out. The oscillation frequency is f.sub.2 during operation of the main supply and automatically switches to a frequency f.sub.1 when the regenerative power supply takes over. The frequency shift is automatic during each half cycle of a 60 Hz AC supply and is in a direction so as to maintain lamp current relatively constant.

Abstract: A flourescent lamp lighting circuit comprising a rectifying circuit and an oscillatory circuit. The rectifying circuit comprises a rectifier bridge, capacitors and coils to rectify the local alternating power supply to direct power supply and provide rectified electrical power to the oscillatory circuit. The oscillatory circuit comprises two transistors and an L-C circuit which, taken together, form an astable circuit which generates and maintains oscillations. The frequency of the oscillations is determined by the nature of L-C circuits. The ON's and OFF's of the transistors are controlled by induction coils within which currents are induced by the variation of magnetic flux in the inductor coil of the L-C circuit. The high frequency oscillations in the oscillatory circuit induce high frequency electrical signals on a secondary coil which then lights the fluorescent lamp.

Abstract: A DC/AC converter (30 to 72) for feeding a low-pressure mercury vapor discharge tube (15) comprises two series-connected main transistors (11 and 20) which, in the operating condition, are alternately conducting. The conduction times of the two transistors (11 and 20) are always kept equal to each other by means of an auxiliary circuit (70 to 72, 32a, 32b, 32c) which influences the operation of a timing circuit (32, 33). This prevents the occurrence cataphoresis in the lamp.

Abstract: Starting and operating apparatus for high intensity discharge lamps includes first and second pairs of terminals formed for connection to an AC source and a discharge lamp respectively, a series connect ballast means and inductor connected to one of said first pair and one of said second pair of terminals a bilateral switch shunted by a capacitor and in series with an AC impedance coupled to the inductor and to the other one of said first and second pair of terminals whereby relatively wide high voltage, high frequency pulse potentials for starting the discharge lamps are provided.

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 current driven gain controlled electronic ballast system (100) is provided having a power source (112) for actuating a pair of gas discharge tubes (140 and 140'). The ballast system (100) includes a filter network (111) which is connected to the power source (112) for establishing a substantially constant voltage signal and suppressing harmonic frequencies generated by the electronic ballast system (100). An induction circuit (115) is coupled to the filter network (111) for generating a voltage across the gas discharge tubes (140 and 140') responsive to the driving current. The induction circuit (115) includes an automatic gain control network (117) to maintain the driving current at a predetermined value and includes a trigger network (117) for generating a switching signal.

Abstract: A luminous gas filled tube system has a direct current source, a pulse transformer secondary winding, the emitter-collector path of a transistor, and the gas filled tube connected in series. The voltage of the source is below the ionization potential of the gas in the tube but adequate to supply current when the gas is ionized. A pulse source is connected for selectively generating a high voltage pulse in the winding of magnitude such that, when added to the voltage from the source, the ionization potential of the gas is exceeded. A starter circuit is provided for selectively actuating the pulse source to initiate ionization of the gas in the tube. A variable resistor is provided for selecting the amount of current flowing in the series circuit at any level below a maximum rating of the transistor.

Abstract: A lamp circuit having a push pull oscillator including an inductance in the D.C. supply, non-resonant coupling circuit to the lamp and cycle-by-cycle frequency control of the oscillator regulated by a lamp current sensor.

Abstract: A D.C. to A.C. inverter using switching transistors driving a multiple-core transformer which includes a high-permeability saturable core upon which both the primary and secondary windings are wound and one or more lower permeability non-saturating cores upon which the primary and/or secondary windings are wound to provide additional self-inductance. The inverter switching transistors drive the two halves of the transformer's center-tapped primary winding on alternate half-cycles under the control of a feedback winding which is wound on the saturable core. A non-saturating core about which the primary winding is wound, and a capacitor connected in parallel with both halves of the primary winding, protects the switching transistors against transients, prevents the saturating core from going into hard saturation, and efficiently transfers energy stored in the leakage inductance of the primary winding from half-cycle to half-cycle.

Abstract: A current fed high frequency oscillator-inverter ballast circuit includes a parallel resonant tank circuit for driving a pair of series connected discharge lamps via a series ballast capacitor. A regenerative power supply switches on when a fluctuating main DC supply voltage drops below a given level thereby providing a constant level auxiliary DC supply voltage to the oscillator inverter to maintain oscillation and lamp operation. When the main DC supply voltage exceeds said given level, the regenerative power supply switches out. The oscillation frequency is f.sub.2 during operation of the main supply and automatically switches to a frequency f.sub.1 when the regenerative power supply takes over. The frequency shift is automatic during each half cycle of a 60 Hz AC supply and is in a direction so as to maintain lamp current relatively constant.

Abstract: A power supply apparatus for a fluorescent lamp comprises an inverter circuit for converting AC line power to a high-frequency drive voltage having a square waveform, this high-frequency drive voltage being applied to a fluorescent lamp through an inductor and a capacitor connected in series to form a series-resonance circuit which provides a ballast impedance after ignition of the fluorescent lamp has been achieved. A sufficiently high voltage to ensure reliable ignition of the fluorescent lamp is ensured by a ringing oscillation which is produced across another capacitor, connected across the lamp, when the fluorescent lamp is in the high-impedance state prior to ignition.

Abstract: A magnetic ballast circuit for a fluorescent lamp providing improved power factor, reduced harmonic content and increased efficiency. A ballast circuit with three inductances connected to a junction, preferably with the first and second inductances comprising a tapped autotransformer, with the third inductance connected between a line terminal and the tap, with the first inductance connected in series with a capacitance to the other line terminal, and with the second inductance connected to the load. The first inductance may be provided totally as part of the autotransformer, or may be supplemented with a second inductance in series. In an alternative embodiment, separate inductances may be utilized.

Abstract: A frequency-modulated converter with a series-parallel resonance, particularly for driving any ohmic or inductive load, including gas discharge tubes, wherein a commutating voltage switch in the form of a transistor is provided and is connected in series between a negative electrode of a direct current voltage source and a first terminal of an inductor, and a pulse generator circuit is provided between the voltage source and the transistor's control electrode and the inductor's second terminal is connected to the primary winding of a transformer. A first capacitor and rectifier diode are also provided in a first and second parallel branch respectively between the transistor's charge receiving and charge emitting electrodes, and a second capacitor is provided across the voltage source's electrodes, and a smoothing capacitance is provided for the voltage source, the second capacitor being connected in series with the inductor via the diode.