Abstract: A power supply includes a switch configured to control flow of current output from an inductor to an output of the power supply. The switch receives a switching signal from a control circuit. An auxiliary bias is generated to power the control circuit. A bias circuit outputs a bias signal that is used to generate the auxiliary bias. The bias circuit senses a level of the auxiliary bias to control output of the bias signal. Output of the bias signal may be controlled to maintain the level of the auxiliary bias at a target level or within a target range.

Abstract: An electrodeless plasma lamp is provided. The lamp includes a conductive enclosure including a dielectric material (e.g., air) and a bulb containing a fill to form a light emitting plasma. A radio frequency (RF) power source is coupled into to the enclosure. At least one conductive applicator applies power from the enclosure to the bulb and at least one limped inductive element is coupled between the RF feed and applicator. The lumped inductive element may be a helically wound coil. In an example embodiment, the lamp includes first and second lumped inductive elements. The first and second lumped inductive elements may extend from opposed end walls of the enclosure. The first lumped inductive element may be connected to a first conductive applicator located proximate a first end of the bulb and the second lumped inductive element may be connected to a second conductive applicator located proximate a second end of the bulb.

Abstract: A circuit arrangement for striking a discharge lamp, comprising: a drive apparatus, having an output adapted to provide a drive signal with a predeterminable frequency; an inverter, which is coupled to the output of the drive apparatus, and having an output adapted to provide a square-wave signal with a predeterminable duty factor; a load circuit, which is coupled to the output of the inverter and has at least one terminal for the discharge lamp, the load circuit comprising a lamp inductor, which is coupled in series between the output of the inverter and the at least one terminal for the discharge lamp; a first control loop with a first reference variable, a first manipulated variable and a first controlled variable, the first control loop having a first time constant; a second control loop with a second reference variable, an auxiliary manipulated variable and a second controlled variable, the second control loop having a second time constant; and a strike detection apparatus, which is adapted to detect str

Abstract: An electronic ballast includes a step-up converter, which includes a storage inductor, a diode, an intermediate circuit condenser and a switch element. According to the invention, a current passing through the storage inductor is used in the form of an indicator of turnon and turnoff times of the step-up converter oscillates in a self-exciting manner.

Abstract: The invention relates to a circuit arrangement which is used to operate a low pressure discharge lamp (EL), wherein the discharge lamp receives power. Said circuit arrangement is embodied in such a manner that power-determination components (C2a, L2a) of the circuit arrangement are embodied in a temperature-dependent manner such that the power consumption of the lamp is limited when the temperature rises. Capacitors (C2a) and throttles (L2a) can be embodied in a temperature-dependent manner in a control circuit (AS) of the circuit arrangement.

Abstract: A system for luminance characterization of a luminaire includes a ballast coil and a multi-tap capacitor connected in series with the ballast coil. The multi-tap capacitor has a plurality of tap capacitors integrated into a capacitor housing. A plurality of switches are each coupled to one of the plurality of tap capacitors for selectively coupling the tap capacitors together to produce a multi-tap capacitance corresponding to a configuration of the plurality of switches. A lamp is connected in series with the multi-tap capacitor and the ballast coil. A photometer is located to measure light intensity of the lamp and to produce a lumen output measurement. A memory is used to store a database having a plurality of lumen output measurements, each corresponding to a multi-tap capacitance corresponding to all configurations of the plurality of switches.

Abstract: In a discharge lamp lighting apparatus to light two discharge lamps, one terminal of the secondary side of a step-up transformer is connected to one terminal of each of the two discharge lamps, the other terminal of each of the two discharge lamps is connected, via each of two variable inductance elements, to one lamp current detecting unit, a signal of each lamp current detecting unit is connected to a lamp current control circuit, and an output signal from each lamp current control circuit is connected to each variable inductance element so as to vary the inductance of each variable inductance element, whereby the lamp current flowing through each discharge lamp is controlled.

Abstract: A dimmer circuit provides AC power to an inductive lighting load in series with the dimmer circuit. A bidirectional semiconductor switch has a control electrode with a control signal for determining the power provided to the load. The switch in normal operation is controlled to block voltage in first and second half-cycles of the AC voltage. In a failure mode it can block the AC voltage in only one half-cycle. A controller for the switch determines the failure mode of the switch occurs which can cause an asymmetry between the half-cycles and thus a DC voltage component. A power supply supplies power to the controller from across the dimmer circuit. The controller drives the switch into substantially full conduction during most of the half-cycle which the switch is able to control; and drive the switch into non-conduction for a period of time during that same half-cycle so as to reduce the DC voltage component to prevent excessive transformer heating.

Abstract: A first vehicle lamp driver circuit for a light emitting diode (LED) array, the LED array having a first string of four LEDs in series and a second string of four LEDs in series. A first LED driver drives the first LED string and a second LED driver drives the second LED string. In a STOP mode of operation, the current to both LED strings is controlled by the LED driver in series with the LED string. In a TAIL mode of operation, the current is provided to only one LED string via a series connected diode and resistor. When there is reduced input voltage, operation of the LED strings is provided by switching circuits that short-out one LED in each LED string. A second vehicle lamp driver circuit comprises a first LED string and a second LED string in series with a control switch having a feedback circuit for maintaining constant current regulation to control the sum of the current in each LED string and reduce switching noise.

Abstract: In accordance with one aspect of the present application, a continuous mode voltage fed inverter includes a resistor starting network configured to start a charging of the inverter. A resonant feedback circuit is configured to generate an oscillating signal following the starting of operation of the circuit by the resistor starting network. A complementary switching network has a pair of complementary common source connected switches configured to receive the oscillation signal generated by the resonant feedback circuit, wherein the oscillation signal determines a switching rate of the complementary pair of switches. A clamping circuit is configured to maintain an inverter current in an inductive mode, wherein the inductive current lags voltage across the pair of complementary common source connected switches. A fold-back circuit is connected, in one embodiment, to the complementary switching network to provide a two-level clamping action.

Abstract: A watertight, low power flashlight is disclosed that uses a voltage tripler and regulator that enables the use of a single AA or lithium battery. The voltage tripler is a “step-up power component” that raises the battery voltage from 1.5 volts to approximately 5 volts required to sufficiently energize the L.E.D.s. The flashlight also includes a lightweight, compact housing with an optional dimmer switch and a side-mounted on/off switch.

Abstract: A DC/DC converter for an electronic equipment, e.g., a self-luminous display apparatus, includes a plurality of choke coils connected in parallel to each other to a DC power supply, a control circuit for controlling the ON/OFF operation of a switching element to control an output voltage of the DC/DC converter, and a changeover switch for selectively changing over the choke coils such that only one of the choke coils which has an inductance value corresponding to the output current of the DC/DC converter is effectively connected to the rectifying diode.

Abstract: The invention relates to a supply coupling of a fluorescent lamp used for supervising the operation and condition of a lamp circuit, particularly a supply coupling in connection with an electronic coupling device wherein the power required by the lamp circuit is supplied to the coupling by a transformer. The supply coupling comprises a supply transformer (T1), a resonance circuit comprising the secondary coil (N2) of the transformer (T1) and a capacitor (C1) connected in parallel with the secondary coil, and a fluorescent tube (Lamp 1) connected in parallel with the resonance circuit and comprising fluorescent cathodes (F1, F2).

Abstract: An electronic operating device for discharge lamps is disclosed in which an output terminal is connected via a coupling capacitor (CB) to a reference potential (E). An electric component (VC) which acts as a voltage source is inserted in series with the coupling capacitor (CB) in order to reduce the potential of an output terminal. The electric component (VC) consists in one embodiment of an inductor which is coupled to the lamp inductor.

Abstract: An electronic flash device of an automatic light adjusting type includes a main capacitor for storing charge at a high voltage. A flash discharge tube generates flash light upon discharging the main capacitor therewith. A light adjusting circuit adjusts a light amount of the flash light by feedback. The light adjusting circuit includes a reflected light measuring unit for outputting an integration voltage for representing a light amount of reflected light from a photographic field illuminated with the flash light. A thyristor as non-contact switch short-circuits terminals of the main capacitor upon being turned on, to quench emission of the flash light in the flash discharge tube. A turn-on capacitor is charged by a current of discharge in response to the emission of the flash light, and is discharged when the integration voltage comes up to a prescribed level, to turn on the thyristor responsively.

Abstract: The invention provides a power supply or drive circuit for a pulsed flashlamp which utilizes a two-core component having common windings as both an inductor for arc mode drive and for breakdown triggering of the lamp. Discharge of a capacitor through the inductor and lamp is controlled by a high speed semiconductor switch which is turned on and off by a suitable control, current flowing from the inductor through a one-way path including the lamp when the switch is off. The control maintains the ratio of the current variation through the lamp to the average current through the lamp substantially constant.

Abstract: A method of generating an electrical discharge in a high pressure gas contained in a sealed enclosure. The method includes driving a helical coil resonator at an RF frequency to generate an RF electric-magnetic field sufficient to generate an electrical discharge in the high pressure gas. The electrical discharge produces an emission spectrum that may be spectroscopically analyzed to determine the composition and impurity content of the gas.

Abstract: A driving circuit for powering an electroluminescent display using energy recovered from a varying panel capacitance of the display. The driving circuit comprises a source of electrical energy; and a resonant circuit using the panel capacitance for receiving the electrical energy and in response generating a sinusoidal voltage to power the display at a resonance frequency which is substantially synchronized to a scanning frequency of the display. The resonant circuit uses a step down transformer to reduce the effective panel capacitance of the display in order to reduce its effect on the resonance frequency.

Abstract: A power saver for discharge lamps, in which supply of electricity is not stopped instantaneously even though applied voltage is converted into lower voltage after lighting the discharge lamp, is disclosed. The power saver for discharge lamps includes a first coil, a second coil having a winding direction opposed to a winding direction of the first coil and located in an opposite direction of the first coil, an insulator located at a gap part where the first coil and the second coil are opposed, at least one or more taps arranged along a longitudinal direction of the second coil, at least one or more switches selectively connected to one of the taps, at least one or more first timers connected to the switches respectively, an electric relay mounted in a loop circuit including both end parts of the second coil, and a second timer connected to the electric relay.

Abstract: A circuit driving an electroluminescent lamp at a frequency at or in the vicinity of the lower threshold of human hearing, thus reducing objectionable noise otherwise generated by such lamps when operated at high frequencies. In an electroluminescent lamp assembly including such driving circuit is described, the electroluminescent lamp is driven at low frequency, but nonetheless provides a high level of illumination output.

Abstract: Disclosed is inductive coupling of power to devices having negative resistances, such as gas-filled discharge lamps (fluorescent tubes, neon signs, and the like) from a primary inductive loop, using resonant conditioning of the power provided to the device. A “C” shaped inductor (202) around the loop and a resonating capacitor (406) in parallel with the inductor provide a current source to the lamp (403) from across the capacitor. The circuit is capable of first igniting a lamp using a higher voltage available when the Q of the unloaded circuit is high, then running the lamp or other device at a controlled current. The lamp current is substantially proportional to the primary inductive loop flux, and substantially independent of the lamp resistance. A second inductor (404) in series with the first though not itself a collector of flux acts as a current limit. Applications include lighting, displays (optionally isolated and dimmable), and production of ultraviolet radiation.

Abstract: The present invention provides a discharge lamp lighting system in which a discharge lamp is lighted by a commercial power source without using a choke transformer, electric power can be saved, and, in order to prevent a bad influence of high harmonic waves generated from the discharge lamp upon other electronic equipment, the impedance ratio resonating with the third high harmonic wave component of the power source is established between a capacitor and a choke coil provided between the discharge lamp and an alternate current power source to facilitate resonance of the third high harmonic wave component, and, when a starting lighting circuit is temporarily turned ON, the discharge lamp is lighted.

Abstract: A system of igniting a gas discharge device having spaced electrodes immersed in a gas, at voltages below the required starter ignition voltage for cold cathodes. A square wave alternating voltage source of between about 75 kHz and 4 MHz is applied directly to the gas discharge device so that the voltage on the spaced electrodes reverses its polarity more rapidly than the pattern of electron and ion density in the gas can shift.

Abstract: A starter for a fluorescent lamp selectively conducts current from an AC power source through a ballast and cathodes of the lamp during one half cycle of conducted current from the AC power source. Thereafter and during the same on half cycle of current the starter ceases conducting current substantially instantaneously when the current is of a predetermined level. The resulting di/dt generates a starting voltage pulse from the ballast sufficient to ignite the plasma. The starting pulse occurs when the AC voltage across the cathodes exceeds an ignition voltage of the plasma. Preferably the starter employs a thyristor which has a predetermined holding current at least equal to the predetermined level to allow the inherent commutation of the thyristor to create the di/dt. The current conducted by the thyristor heats the cathodes prior to igniting the plasma.

Abstract: A solid state, bipolar, ignition exciter for gas turbine engines is described for delivering high energy pulses to one or more igniter plugs. A storage capacitor is charged with typically 12 to 20 Joules of stored energy and discharged through a solid state switch and a series-connected ignitor plug. The solid state switch consists of a plurality of silicon controlled rectifiers (SCRs) connected in series, in combination with other components connected in parallel with each SCR. Protection is provided against transients in voltage by means of resistance-capacitance snubber circuits connected in parallel with each SCR. Protection is provided against transients in current by means of inductance connected externally, and in series with, the solid state switch. Protection is provided against damage from reverse voltages by means of a reverse current path through the solid state switch, typically by means of a diode or series-connected diode chain connected in parallel with the SCRs.

Abstract: A ballast circuit arrangement with hot restrike capabilities includes an input transformer having a primary winding receptive of line power and a secondary winding over which an output voltage is made available. A first capacitor coupled across the secondary winding of the input transformer develops a voltage charge thereon. A resistor and a second capacitor are series connected to one another and are parallel coupled across the first capacitor. A starting aid device is coupled to the secondary winding of the input transformer and produces an output voltage of a predetermined magnitude. The output voltage of the starting aid is coupled to a spark gap device having first, second and third electrodes associated therewith. A first spark gap formed between the second and third electrode is first fired by the output voltage of the starting aid which in turn triggers the firing of a second spark gap formed between the first and second electrodes.

Abstract: In a fluorescent lamp ballast, a high-frequency AC voltage is applied directly across a tuned L-C circuit. The fluorescent lamp is connected in parallel with the capacitor of the L-C circuit and a voltage-limiting means prevents the series-resonating L-C circuit from overloading the source of AC voltage during any period when the lamp is not effective in providing circuit loading. When power is initially applied to the L-C circuit, a control means provides a short circuit across the capacitor; and, by way of a first current transformer, the resulting short circuit current is used for pre-heating the fluorescent lamp cathodes. After about 1.5 second, the control means provides for removal of the short circuit for a period of about 25 milli-seconds, thereby permitting the voltage across the capacitor to grow to a magnitude sufficient to ignite and operate the lamp, while at the same time removing the cathode voltage.

Abstract: An efficient ballast for Mini-fluorescent lamps, includes an inductor, in communication with a power source and constructed as transformer with only primary winding, a fluorescent lamp in series with the inductor, and a capacitor in series with the fluorescent lamp, and optionally may include a resistor in parallel with the coil, and a switch interposed between the capacitor and power source. The value of the capacitance may change based upon the degree of change in the supply voltage.

Abstract: An inverter device includes an input power-factor improving circuit which causes part of a high frequency output of an inverter circuit to feedback, through an impedance element forming at least part of two oscillatory systems, to a rectified output end of a rectifier, and a high-frequency current supply to the rectifier to be made substantially over entire range of an AC source voltage, and a control means operates the inverter circuit at a fixed frequency for attaining the two oscillatory systems in which the output supplied to a load is substantially equalized, whereby ripple component giving ill influence on the load can be remarkably reduced.

Abstract: This invention relates to an unnecessary electromagnetic wave shielding structure of a magnetron for a microwave oven, comprising an electric wave absorbent filament ceramic disposed adjacent the lower end of a power input section to prevent unnecessary electromagnetic waves produced in an active space from being leaked from the input section through a center lead extending downwardly from an upper end shield of the active space and a side lead disposed adjacent the center lead; first and second ferrite cores having different frequency characteristics and inserted concentrically over the filament ceramics at the respective upper and lower sides of the outer periphery thereof to cooperate with the ceramics to shield the unnecessary electromagnetic waves; and an annular insulator placed between the second ferrite core and filament terminals to insulate the ferrite core from the terminals.

Abstract: The Lamp (La) is connected in series with first reactive impedances (C1, . To generate pulses, one or more second reactive impedances (C3, L3; C3-L2) are located as energy storage elements in series with one or more switch elements (S3, VTh1, VD1) to at least one of the first reactive impedances (C1, L1) and also in series with the high-pressure gas discharge lamp.

Abstract: To eliminate the necessity for a saturated or air gap inductance to provide feedback circuit for a self-exciting oscillator including two active electronic switches (T1, T2) , for example MOSFETs, an auxiliary winding (HW1, HW2, . . . HW11) is inductively coupled to the resonance inductance (L2) present in the circuit for the discharge lamp (LP) anyway; and a pulse shaping - phase shifting network (R3, C3; R4, C4 . . . ) , devoid of inherent resonance, coupling the auxiliary winding to the active switching elements. The pulse shaping - phase shifting network is formed of a one or multiple-stage RC low-pass circuit, connected serially between the auxiliary winding and the control input, for example the gate, of the active switching element. The RC network can be constructed with variable elements, for example including PTC resistors, a varistor or the like, and may include a current source, protective circuits to protect against voltage peaks including Zener diodes.

Abstract: A circuit for lighting a fluorescent lamp. The present invention takes into account the fastidious characteristics of the fluorescent lamp, and during the momentary lighting of the fluorescent lamp. In order to reduce the temperature fluctuations, a separate pre-heating power is supplied. The circuit includes: a first resonance circuit consisting of a first capacitor connected to the opposite ends of the fluorescent lamp, a resonance inductor, a second capacitor, a first switch and a DC power source, serially connected; a second resonance circuit consisting of a second switch, a first capacitor, a resonance inductor, a third capacitor and a DC power source, serially connected; a switch control circuit for activating the first and second switches in an alternate manner. Before the lighting of the fluorescent lamp, the first and second resonance circuits are put to a resonance state, while, after the lighting of the fluorescent lamp, the resonance is eliminated.

Abstract: A discharge lamp lighting apparatus comprises a transformer for stepping up an AC power source voltage from an AC power source to produce a high voltage as an output voltage required for lighting a discharge lamp. Particularly, the lighting apparatus further comprises a diode for rectifying the output voltage of the transformer to be supplied to the discharge lamp. The amount of current supply from the AC power source is determined to obtain an output impedance capable of limiting the current which is to flow through the discharge lamp after the start of discharging to maintain the voltage across the discharge lamp at a level required for continuing the discharge.

Abstract: A magnetic-type ballast powers an F40/T12 four foot fluorescent lamp from a regular 120 Volt/60 Hz power line by way of a main inductor. A power factor correction capacitor is connected in series with an auxiliary inductor of relatively small inductance value, thereby forming a series-combination; which series-combination is connected across the power line. A 30 Volt/60 Hz voltage is established across this auxiliary inductor. The phasing of this 30 Volt/60 Hz voltage is opposite that of the 120 Volt/60 Hz power line voltage. Thus, by adding the 30 Volt/.alpha.Hz voltage to the 120 Volt/60 Hz voltage, a 150 Volt/60 Hz voltage is obtained; which 150 Volt/60 Hz voltage is of magnitude adequate to properly power the F40/T12 four foot fluorescent lamp, although it is not of magnitude adequate to provide proper lamp ignition in a rapid-start mode.

Abstract: A ballast circuit for operating a metal halide lamp by applying DC excitation during its start, glow and run modes is disclosed. The type and values of the circuit components of the ballast circuit are selected to provide automatic, sequential and desired transfer functions as the impedance value of the metal halide lamp transitions from its value occurring during the start, glow and run modes of operation. The ballast circuit has an input stage that is easily adapted to present a high power factor to the AC power source supplying the metal halide lamp. Further, the ballast circuit generates a signal for more easily starting the lamp and having a relatively high DC level upon which are developed pulse signals.

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: In a fluorescent lamp device, a discharge tube is made by arranging electrodes at the ends of a glass tube, sealing mercury and a rare gas into the glass tube and coating the inner surface of the glass tube with a phosphor, and an amalgam forming material is disposed close to one or the other of the ends of the discharge tube. This fluorescent lamp is operated with a d.c. current using as the anode the electrode arranged on the discharge tube end side where the amalgam forming material is located.

Abstract: A low voltage electronic starter for an L-C Ballast of a fluorescent lamp is provided having a switching circuit having a resistive-capacitive network, a diac and triac, a transformer and a voltage multiplying rectifier.

Abstract: A starting and operating circuit for high pressure discharge lamps including a pair of input terminals for connection to an alternating current supply and a pair of output terminals for connection across the lamp. A ballast inductor is connected at its ends in series between one of the input terminals and one of the output terminals and a pulse generator is connected between the output terminals. The pulse generator comprises a non-linear capacitor (NLC) and a semiconductor bipolar thyristor (commonly known as a SIDAC) connected in series, the non-linear capacitor and bipolar thyristor being connected in parallel with the discharge lamp.

Abstract: There is disclosed a device and process for starting up a fluorescent discharge lamp in which a high-frequency pulse is generated having narrow voltage peaks above the voltage required to start electric discharge and broad valleys, applied to the elements of the lamp to effect start up of fluorescence and, after start-up, the voltage automatically goes back to maintenance voltage having broad peaks at the maintenance voltage and relatively narrow valleys. The automatic cutback is effected by the load introduced by the electric discharge and the feedback from the emitter of the transistor used to generate the pulse. A capacitor is serially-connected in the lamp circuit to inhibit the flow of DC current therein.

Abstract: A circuit system for igniting and lighting a high-pressure discharge lamp, particularly a sodium vapor lamp, comprising a pulse generator for generating signals of at least 1 kHz frequency being a high-frequency DC/AC converter connected to a direct current source and an ignition circuit coupled with the pulse generator including a high-pressure discharge lamp, a condenser connected in parallel to the high-pressure discharge lamp and an inductive member connected to the condenser and the high-pressure discharge lamp and forming a series member with the condenser the ignition circuit is provided with a transformer having a secondary winding connected in series with the inductive member for ensuring high reliability of igniting and for improving the conditions of lighting.

Abstract: An electronic ballast circuit for fluorescent or other gaseous discharge lamps includes a resonant half-bridge inverter circuit. The source voltage to the inverter is a full-wave rectified line voltage together with a DC carry-over voltage for supplying power in the inter-cusp period of the recitified line voltage. A negative feedback circuit is responsive to lamp current to vary the inverter drive frequency and thereby regulate lamp current. The frequency response of the feedback loop is high enough and the gain-versus-frequency response of the inverter is such that lamp current and voltage are regulated to reduce the crest factor of lamp current to compensate for variation in the amplitude of the voltage across the semi-conductor switches.

Abstract: A circuit for operating low-pressure discharge lamps at elevated frequency comprises a reconnect circuit which disables the disconnect circuit upon exchange of a defective low-pressure discharge lamp (LP1). The disconnect circuit comprises a diode (D10), a resistor (R11) and a thyristor (TH) together with a trigger circuit (5). The reconnect circuit comprises a capacitor (C9) and a resistor (R12). Upon removal of the defective low-pressure discharge lamp (LP1), the capacitor (C9) is charged over the resistor (R12). Upon insertion of a new low-pressure discharge lamp (LP1), the capacitor (C9) is discharged and recharged in opposite direction and the holding current is removed from the thyristor (TH). This causes the thyristor (TH) to block, and enables the push-pull frequency generator (3) to start oscillating again.

Abstract: A ballast adaptor circuit which makes it possible to convert a conventional two lamp rapid start T12 ballast for operation of two T8 fluorescent lamps and by means of a simple modification that does not require cutting wires or extensive rewiring of the T12 ballast device. The adaptor circuit comprises an auxiliary circuit including a tuned series-parallel LC network connected in parallel with either one or both of the lamps. The LC network is tuned to supply an odd harmonic current to the lamps, preferably the seventh harmonic. Improved starting is achieved by adding a series RC circuit and a SIDAC trigger device to the network to produce voltage pulses at the peaks of the AC supply voltage.

Abstract: A circuit for switching a current in an inductive load comprising at least one transistor (1) which switches through its collector-emitter path the current in the load (7). The base is coupled to the emitter through a voltage-stabilizing element (5) for stabilizing the voltage supplied to the base. A dissipation device is usually added to the circuit for dissipating currents or voltages occurring in a sense opposite to the sense of conduction of the transistor (1). A simplification of the circuit and hence a decrease in the cost thereof is achieved in that the voltage-stabilizing element (5) also serves as the dissipation device.

Abstract: A power supply circuit comprises a single discharge capacitor having a charging sufficient to trigger discharge in a discharge lamp. The discharge capacitor is associated with means for accumulating energy, with which it is charged. The energy accumulating means receives commercially available alternating current and applies the accumulated energy to the discharge capacitor to charge the latter. The power supply circuit may include an auxiliary capacitor which has a smaller capacitance and higher potential rating than the discharge capacitor. The auxiliary capacitor may have a potential rating sufficient to activate the discharge lamp alone. The discharge capacitor cooperates with the auxiliary capacitor to define discharge period. Preferably, the power supply circuit may include means for blocking or shutting off power supply at a given timing to precisely control the discharge period.

Abstract: A lighting apparatus which provides high voltage pulses for starting a high pressure sodium lamp. The apparatus includes two capacitors, two blocking diodes, a voltage sensitive symmetrical switch, and multiple resistances across which pulses are distributed. The aforementioned elements are electrically connected together and with a tapped ballast reactor so that one of the capacitors charges through an impedance in the negative half-cycle, and thereafter, when line voltage goes positive, the other capacitor charges through an impedance equal to the sum of the multiple resistances. When the voltage of the capacitors reaches a predetermined voltage exceeding the breakdown voltage of the voltage sensitive symmetrical switch, the capacitors discharge. This discharge, because of an autotransformer relationship within the reactor, produces a high voltage pulse of predetermined height and width once per each cycle of the source voltage.

Abstract: An electronic ballast is adapted for operation on regular 120 volt/60 Hz power line voltage and comprises: (i) full bridge rectifier means, (ii) ripple filter means consisting of an LC circuit series-resonant at 120 Hz, (iii) self-oscillating inverter means operating into an LC output circuit parallel-resonant at about 30 kHz, and (iv) means to disable the inverter in case a 30 kHz ground-fault current flows from its output circuit. A key element in achieving high reliability as well as high durability relates to the use of the series-resonant LC circuit instead of the conventional electrolytic capacitor for DC voltage ripple filtering. A key element in achieving high efficiency relates to the use of ground-fault interruption to achieve the required safety from electric shock hazard, thereby obviating the need for the more conventionally used isolation transformer with its attendant added cost and inefficiency.

Abstract: The enclosed electronic flash device for a camera includes a booster circuit connectible to an electrical power source or battery, a high voltage rectifier diode for rectifying the output of the booster circuit, and a storage capacitor. A main power supply switch and an auxiliary power supply switch are connected in series between the negative poles of the power source and capacitor. The auxiliary power supply switch is arranged to close when the flash device is attached to the camera. A signal terminal is connected to the negative pole of the storage capacitor through other circuit elements and another signal terminal is connected to one contact of the auxiliary power supply switch, which is connected in turn to the negative pole of the storage capacitor. The auxiliary power supply switch is connected in series with the main power supply switch at a point farther from the negative terminal of the battery than the main power supply switch.