Abstract: A control section is used to control a DC-to-AC converter circuit to perform lighting control of a discharge lamp. A transformer, switching elements, and a capacitor for resonance are included. The switching elements are driven and serial resonance of the capacitor and the inductance component of the transformer or an inductance element is produced. Before the discharge lamp is turned on, control is performed to cause the driving frequency of the switching elements to gradually approach Foff and to supply a start signal to the discharge lamp. Once the discharge lamp is turned on, control is performed to continuously change the driving frequency from f1 assumed before the discharge lamp is turned on to f2. A residence time in a frequency range lower than Fon is secured then the frequency is shifted to a frequency range fb higher than Fon, or an inductive range fb.

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, via each of two variable inductance elements, to one terminal of each of the two discharge lamps, the other terminal of each of the two discharge lamp is connected to one lamp current detecting unit connected to a lamp current control circuit, a switch is provided at the previous step of the lamp current control circuit, an output signal from one phase adjusting circuit is connected, via the switch, to the connection portion of the lamp current detecting unit and the lamp current control circuit, and the inductance of each variable inductance element is varied by an output signal which is sent from the lamp current control circuit, and which has a phase shifted from others, whereby the lamp current flowing through each discharge lamp is controlled.

Abstract: An embodiment of a discharge lamp lighting apparatus of the present invention includes a socket inserted with a discharge bulb, a transformer having a coil including a secondary side winding connected at one end to the socket, connected at the other end to a first drive wire, and a primary side winding connected at one end to a second drive wire, connected at the other end to a third drive wire through a discharge gap, a core inserted into the coil, and a resin filled between the core and the primary side winding, the secondary side winding, and a capacitor connected between the second drive wire and the third drive wire, wherein the transformer and the socket are aligned side by side.

Abstract: A lighting device for high-pressure discharge lamp for lighting the high-pressure discharge lamp by lowering or raising a DC voltage applied to an input side by a DC/DC converter circuit, then converting the DC power into an AC power by a DC/AC inverter circuit, supplying the AC power to the high-pressure discharge lamp and lighting the high-pressure discharge lamp, wherein when the polarity of the current of the high-pressure discharge lamp lit by the substantially rectangular wave is inverted, the output voltage of the DC/DC converter circuit is set to 1.5 times or more as large as the voltage at the stable lighting time of the high-pressure discharge lamp.

Abstract: A power converter includes a control device (28) for a switching power converter (10), a switching power converter and a method of controlling a switch in a power converter for reducing audible noise. The power converter includes the control device (28) and at least one switch (26) for regulating the power conversion. The control device (28) includes a timer (45) for monitoring a switching frequency of the switch (26) to indicate when the frequency has dropped to a certain level, and a gate driving circuit (32) connected to the timer and arranged to regulate the switching of the switch in dependence of the indication from the timer, so that the frequency rises above the certain level in order to reduce generation of audible noise.

Abstract: A DC/AC converter circuit structure for driving a plurality of cold cathode fluorescent lamps is described. A common-mode choke is used between the cold cathode fluorescent lamps. The common-mode choke balances the currents respectively flowing through the cold cathode fluorescent lamps.

Abstract: An apparatus and method for driving a lamp are provided. In one embodiment, an inverter having four switching elements is split into two inverter arms that are deployed at separate terminals of a floating lamp structure to achieve even light output. A controller drives both inverter arms such that power switching lines do not cross the floating lamp structure. In one embodiment, the controller adjusts the brightness of the lamp structure by adjusting the phase difference between outputs of a first inverter arm relative to a second inverter arm. In one embodiment, the controller adjusts the brightness by symmetrically pulse width modulating the outputs of the first inverter arm and the second inverter arm.

Abstract: A lamp driving apparatus of a liquid crystal display device includes m lamp groups in which a plurality of lamps generating light are disposed; n (n<m) inverter parts to generate an AC voltage for driving the lamps; an inverter controller to control the inverter parts; and a multiplexer to selectively supply the AC voltage generated at the n inverter parts to the n lamp groups among the m lamp groups. In each frame, a clock signal is divided into n divided signals. Different sets of lamp groups are driven during each of the divided signals.

Abstract: An efficient and flexible current-mode driver delivers power to one or more light sources in a backlight system. In one application, the current-mode driver is configured as an inverter with an input current regulator, a non-resonant polarity-switching network, and a closely-coupled output transformer. The input current regulator can output a regulated current source in a variety of programmable wave shapes. The current-mode driver may further include a rectifier circuit and a second polarity-switching network between the closely-coupled output transformer and a lamp load. In another application, the current-mode driver delivers power to a plurality of light sources in substantially one polarity by providing a regulated current to a network of time-sharing semiconductor switches coupled in series with different light sources coupled across each semiconductor switch.

Abstract: An apparatus for detecting the reconnection of a lamp filament to an electronic ballast driving a fluorescent lamp. A control circuit controls an inverter circuit to providing power to a filament control circuit. The filament control circuit preheats and powers the lamp filament of the one or more lamps. A pulse generator generates an input signal as a function of the number of lamp filament connected to the filament control circuit. A current sensor generates a first voltage indicative of whether a lamp filament has been reconnected to the circuit. A peak detector generates a peak voltage signal when the first voltage indicates a reconnection of a lamp filament has occurred. A sensing circuit generates a command signal to provide to the control circuit to supply power to the filament control circuit to preheat and power the lamp when the peak detector generates the peak voltage signal.

Abstract: A ballast circuit is disclosed for inductively providing power to a load. The ballast circuit includes an oscillator, a driver, a switching circuit, a resonant tank circuit and a current sensing circuit. The current sensing circuit provides a current feedback signal to the oscillator that is representative of the current in the resonant tank circuit. The current feedback signal drives the frequency of the ballast circuit causing the ballast circuit to seek resonance. The ballast circuit preferably includes a current limit circuit that is inductively coupled to the resonant tank circuit. The current limit circuit disables the ballast circuit when the current in the ballast circuit exceeds a predetermined threshold or falls outside a predetermined range.

Abstract: Switching elements S1, S2 connected in series are provided on the secondary side of a pulse transformer T to which an input voltage is supplied from a DC power supply E. On the primary side of the pulse transformer T, switching element S3, S4 are provided, and a regenerating unit RG including a current limiting inductor L1 and a regenerating inductor L2 is connected to the DC power supply E and the primary side of the pulse transformer T. A current is limited by the inductor L1 during an on time of the element S3 or S4, whilst a current is regeneratively supplied to the DC power supply E by using the inductor L2 during the off time of the elements S3, S4.

Abstract: A two-wire triac-based low voltage AC dimmer adapted for configuration in series with a typically incandescent lighting load. An external step-down transformer provides a source of low AC voltage, and a separate, electrically isoated loop circuit utilizing a step-up transformer converts a portion of the low AC voltage into a corresponding high AC voltage used to trigger the gate of a triac. An on/off arrangement that serves to lock the triac in its blocking may optionally be provided. A shunting resistor connected across the triac serves to dissipate static charge buildup that may otherwise falsely trigger the triac to its on state. A phi filter provides a smoother and more regulated triggering pulse to the triac, thereby minimizing or eliminating flickering and undesirable extinguishing of the incandescent lighting load at low brightness settings.

Abstract: A secondary winding W2 of a step-up transformer of a self-excited inverter 2 is grounded at the midpoint thereof. High-frequency voltages differing in polarity from each other are outputted from both terminals OT1 and OT2 of the secondary winding W2. Two U-shaped cold-cathode tubes L1 and L2 series-connected to each other are provided directly below a liquid crystal panel. One of terminals of the secondary winding W2 is connected to the terminal OT1 through the ballast capacitor C1. The other terminal thereof is connected to the terminal OT2 of the ballast capacitor C2. The connecting point P between the two U-shaped cold-cathode tubes L1 and L2 is ungrounded. Thus, electric currents flowing through the cold-cathode tubes are equal in value to each other.

Abstract: Systems and methods are provided for operating a fluorescent tube having a pair of filaments. The system comprises a transformer, an AC signal generator and a coupling device. The AC signal generator is connected to drive a primary AC signal onto the primary winding of the transformer and to thereby create a secondary AC signal on the secondary winding of the transformer. The secondary winding of the transformer is coupled between the filaments of the fluorescent tube at first terminals thereof. The coupling device is coupled between the filaments at second terminals thereof. The coupling device is switchable between a conducting state, wherein a majority of the current associated with the secondary AC signal is conducted by the coupling device, and a non-conducting state wherein a voltage drop across the coupling device is sufficient to cause a majority of the current associated with the secondary AC signal to arc between the filaments of the fluorescent tube.

Abstract: A compensation circuit for protecting a lamp from a large transient current. The compensation circuit may include a saw tooth generator configured to generate a saw tooth signal with an amplitude corresponding to a supply voltage of the lamp. A pulse width modulated signal may be generated by a comparator of the compensation circuit based on the saw tooth signal and a DC signal. The duty cycle of the pulse width modulated signal may be used by a controller to control the duration of time that current flows through the lamp. When the supply voltage of the lamp transitions from a low voltage to a high voltage, the amplitude of the saw tooth signal increases. When the amplitude of the saw tooth signal increases, the duty cycle of the pulse width modulated signal decreases thereby causing the controller to decrease the duration of time that current flows through the lamp.

Abstract: The present invention discloses a push-pull inverter circuit comprising a transformer with a power output end coupled to a load and two power input ends, and a power driver unit is connected between the two power output ends and a power supply unit, and the power driver unit receives a power signal and outputs two sets of drive signals having same frequency and opposite phase to the two power input ends as to constitute an inverter circuit that adopts a push-pull voltage drive signal to drive the transformer to operate and improve the output power of the transformer.

Abstract: The invention relates to a converter circuit with coupled inductances L1 and L2 which have a core K having an air gap S which is asymmetrical with respect to the inductances.

Abstract: An inverter circuit for discharge lamps, in which transformers are separated into multiple small or middle-sized transformers connected to one another to provide a high-power transformer equivalent to a large transformer. The inverter circuit includes a plurality of leakage flux step-up transformers each having a magnetically continuous central core, a primary winding, and a distributed-constant secondary winding, wherein a part of a resonance circuit is formed among a leakage inductance produced on the secondary winding side, a distributed capacitance of the secondary winding and a parasitic capacitance produced around a discharge lamp close to a proximity conductor, and as the resonance circuit resonates, the secondary winding has a close coupling portion in a vicinity of the primary winding which has a magnetic phase close to that of the primary winding and magnetically close couples with the primary winding.

Abstract: A ballast for at least one lamp at least two switches arranged in series; a control circuit for alternately opening and closing the two switches; a connection for applying a supply voltage to the two switches; a resonant starting circuit coupled on the input side to the junction point between the two switches and on the output side to a first connection for the lamp, the resonant starting circuit having a resonant inductance arranged in series with the junction point between the two switches (S1, S2) and the first connection for the lamp, and a resonant capacitance arranged for alternating current purposes in parallel with the first and second connections for the lamp, a first braking inductance which, for alternating current purposes, is firstly arranged in series with the first of the two connections for the lamp and secondly in parallel with the resonant capacitance.

Abstract: An inductive power supply system for providing power to one or more inductively powered devices. The system includes a mechanism for varying the physical distance or the respective orientation between the primary coil and secondary coil to control the amount of power supplied to the inductively powered device. In another aspect, the present invention is directed to an inductive power supply system having a primary coil and a receptacle disposed within the magnetic field generated by the primary coil. One or more inductively powered devices are placed randomly within the receptacle to receive power inductively from the primary coil. The power supply circuit includes circuitry for adjusting the power supplied to the primary coil to optimize operation based on the position and cumulative characteristics of the inductively powered device(s) disposed within the receptacle.

Abstract: An AC to AC power conversion apparatus with constant power feeding characteristics to fluorescent lamp or FD lamp is described. The constant power characteristic is achieved by discontinuous mode operation of capacitor coupled in series with the load. Packets of energy are pumped out to the load in each switching cycle, regardless of the resonant characteristics. The dependence of the input power on the square of the supply voltage make the input resistive and produces good power factor automatically. The lamp load is dimmable by external phase control dimmer like resistive incandescent lamps. Multiple lamp loads with different power rating can be integrated by adding more sets of said capacitors and associated components.

Abstract: A transformer. The transformer drives a plurality of lighting tubes and comprises a coupling iron core, a first winding around the coupling iron core, a first bobbin disposed between the first winding and the coupling iron core, a plurality of second windings, independent of each other and respectively winding around the exterior of the first winding, wherein the second windings have the same winding number, and a second bobbin disposed between the first winding and one second winding.

Abstract: This invention relates to new soft-switching techniques for minimizing switching losses and stress in power electronic circuits using inverter legs. By choosing the switching frequency with specific relationships with the resonant frequency of the power electronic circuits, the proposed switching technique enables the power electronic circuits to achieve soft switching under full load and short-circuit conditions at the defined frequencies for both capacitive and inductive loads. This technique can be applied to an electronic circuit with two switches connected in totem pole configuration between two dc voltage rails or commonly known as a power inverter leg or inverter arm. Examples of these circuits are class-D power converter, half-bridge power converters and full-bridge power converters or inverters. The proposed techniques allow inverter circuits with resistive, capacitive and inductive loads to achieve soft switching.

Abstract: An electronic device having an illumination circuit. The illumination circuit utilizes an AC current of an AC driving device to drive an illumination device such as an electroluminescent lamp and the remaining life of the AC driving device indicated by the brightness of illumination device.

Abstract: An apparatus for providing convenient transforming of electrical energy from a first voltage level to a second voltage level, includes a housing having an end wherein the end includes a conductive threading and a contact for making an electrical connection with a light bulb socket. The apparatus also includes a transformer electrically connected to the electrical connection for receiving power through the light bulb socket and transforming the received electrical energy from the first voltage level to the second voltage level. There is a connection electrically connected to outputs of the transformer to provide power at the second voltage level. The converted power can be used to power a DC-driven device such as an LED.

Abstract: A ballast device having active ballasting circuit and method thereof, which are used for controlling a HID lamp's power supply real-timely and steadily, comprising: a power supply unit in said ballast device for generating an outer working voltage, which has a DC-DC transformer to step down the output voltage; a micro control unit, which fetches the parameters of the ballast device other than itself or the HID lamp's various working status and generates a predefined load current by these parameters; a PWM control unit, which has a PID control module, the PID control module calculates said predefined load current and the HID lamp's practical load current, and makes said DC-DC transformer change it's output voltage by the calculate results. The present invention has a simple structure and can change the load current real-timely and steadily.

Abstract: A ballast and its operating method for a dielectrically impeded discharge lamp. The ballast contains a transformer having a third winding which can be short-circuited via a switch. By so doing, the injection of the voltage pulse into the lamp circuit may be controlled by an external trigger signal.

Abstract: There is provided a vehicular lamp that can flow an electric current having a predetermined variation ratio into each of a plurality of semiconductor light-emitting element units and can individually illuminate each of the plurality of semiconductor light-emitting element units.

Abstract: A low cost DC—DC converter which facilitates a reduction of the switching loss in a wide, variable range of the continuity ratio of the main switching device includes a direct current source; an ON-OFF-controllable main switching device; a main coil which is series connected to the main switching device; a fly-wheel diode which is arranged such that the induction current of the above described main coil flows when the main switching device is shifted into the OFF state; a smoothing capacitor for smoothing the output of the main coil; an auxiliary coil, a resonant capacitor and an ON-OFF-controllable auxiliary switching device. The main switching device and the auxiliary switching device are controlled such that each are alternatively shifted into the ON state such that the main switching device is shifted into the ON state within a given time after the auxiliary switching device has been shifted into the OFF state.

Abstract: A DC-DC converter which accomplishes a reduction of the switching loss in the wide, variable range of the continuity ratio of the main switching device includes a direct current source, an ON-OFF-controllable main switching device, a main coil which is series connected to the main switching device, a fly-wheel diode which is arranged such that the induction current of the above described main coil flows when the main switching device is shifted into the OFF state, a smoothing capacitor for smoothing the output of the main coil, an auxiliary coil, a resonant capacitor and an ON-OFF-controllable auxiliary switching device, in which the auxiliary coil and the resonant capacitor are series-connected to form a LC series connection. Further, the LC series connection, the main switching device and the fly-wheel diode are also series connected, with the auxiliary switching device being connected in parallel to the LC series connection.

Abstract: A multi-lamp backlight system. The system includes a core, a first coil set wrapped around the core, to which a first AC voltage is applied, a second and third coil sets wrapped around the core and respectively disposed on two sides of the first coil set, on which a second and third AC voltage are induced by the first voltage signal applied to the first coil set respectively, wherein the numbers of coils of the second and third coil sets are substantially the same, and first and second lamps are supplied with power by the second and third AC voltages respectively.

Abstract: The present invention provides a driving circuit for driving a light source. The driving circuit includes a serial-arranged transformers system having multiple primary windings and secondary windings; a first switch conducting current though a first path and a second switch conducting current though a second path. The first path is a first set of primary windings connected in series and the second path is a second set of primary windings connected in series and the first set of primary transformer windings and the second set of primary transformer windings form the dual primary windings of the transformers respectively. Based on the conduction of each switch, a DC voltage source supplies power to the primary windings of the transformers, which in turn powers on the light source connected to the secondary windings of the transformers.

Abstract: In a fly-back DC voltage conversion circuit, a transformer accumulates energy during the on-state of a switching element, and the accumulated energy is outputted from a secondary winding during the off-state of the switching element. The switching element is placed in the on-state when the accumulated energy is completely outputted from the secondary winding. A voltage applied to the switching element is differentiated by a capacitor to detect a discharge termination point at which the current of the transformer becomes zero to change a switching frequency of the switching element. The DC voltage conversion circuit can attain control in a current boundary state without significantly increasing cost.

Abstract: A discharge lamp starter includes a DC/DC converter. The DC/DC converter includes a forward section for producing a first output voltage that is determined by a power supply voltage and a turn ratio of a transformer, and a flyback section for producing a second output voltage that is determined by an inductance of a primary winding of the transformer and a current flowing through the primary winding. The DC/DC converter generates its output voltage by adding the first output voltage and the second output voltage. The configuration can reduce the size of the discharge lamp starter.

Abstract: A state detection device is disclosed that is for detecting driving states of plural loads which are connected with each other in parallel and are driven by a driving unit. The state detection device includes a voltage detection unit for detecting voltages applied to the loads; a combined voltage generation unit for generating a combined voltage equivalent to a combination of the detected voltages; and a state detection unit for detecting driving states of the loads based on a magnitude of the combined voltage and magnitudes of the voltages applied to the loads.

Abstract: The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a transformer system for use with either a dimmer switch or an on/off switch, including: a transformer; a load connected to the transformer; a first tap connected to the transformer to provide a first voltage; and a second tap connected to the transformer to provide a second voltage higher than the first voltage. A method of using the transformer system is also provided.

Abstract: An inverter circuit capable of adjusting power factor transforms an AC signal of an electric power source to a pulse DC signal through a rectification unit and divides the duty cycle of minimum input voltage-maximum input voltage-minimum input voltage of the pulse DC signal to a plurality of continuous voltage pulses through an actuation unit so that a transformer outputs an altering duty cycle according to the resonant operation of each voltage pulse and enables a cold cathode lamp to blink in a dark-light-dark fashion to adjust the power factor without adding a power factor adjustment device.

Abstract: The invention relates to an electronic ballast for a dielectrically impeded discharge lamp (L), which ballast has an inductor (W1, W2, W3) with a winding (W2) that can be short-circuited.

Abstract: The invention relates to a method and a circuit for starting or operating discharge lamps which are designed for dielectrically impeded discharges. In this case, it is established in advance, with the aid of an overvoltage protection circuit and test power pulses, whether the discharge lamp is connected.

Abstract: A description is given of a gas-discharge lamp base (11) with a housing comprising an upper part (10) and a cover (40), a support (16) accommodated in the housing for receiving the components, with a transformer, with inductances connected in series with the lamp (1) and a capacitance connected in parallel with the lamp (1), the transformer comprising a bar transformer (23). This construction permits particularly efficient production, because the support can be constructed as a simple leadframe which permits automatic component fitting.

Abstract: A first block (1) converts a DC voltage (Vi) into an AC voltage (V) of a high frequency, using a high-frequency oscillator circuit (4) and a step-up transformer (5). The first block (1) acts as a low-impedance power supply owing to suppression of leakage flux in the step-up transformer (5). A second block (2) and a third block (3) are connected to each CCFL (20). A ballast inductor (LB) causes the CCFL (20) to shine through the resonance with a matching capacitor (CM), and then maintains the stable lamp current during shining of the CCFL (20). The capacitance of the matching capacitor (CM) is separately adjusted for each CCFL (20), and thereby, the total impedance of the matching capacitor (CM) and the surrounding stray capacitances is matched to the impedance of the series connection of the ballast inductor (LB) and an overcurrent protection capacitor (CP).

Abstract: The invention relates to a self-oscillating inverter circuit, preferably having bipolar transistors in a half-bridge circuit, having a transformer as the feedback means. In contrast to the prior art, the secondary windings of the transformer are not connected in parallel with the base-emitter path but in series with the collector-emitter path. As a result, no saturation transformers are required for feedback.

Abstract: Disclosed herein is a backlight inverter for a U-shaped lamp which is capable of detecting an abnormal state of an inverter circuit. The backlight inverter comprises a driver for supplying first and second transformer drive voltages in response to an operation control signal and cutting off the supply of the transformer drive voltages in response to a shutdown control signal, first and second transformers for boosting the transformer drive voltage in a turn ratio between primary and secondary windings thereof and supplying the resulting drive voltage to the U-shaped lamp, first and second voltage detectors for detecting voltages across the secondary windings, respectively, first and second current detectors for detecting currents flowing through the secondary windings of the first and second transformers, respectively, an inverter abnormal state detector for detecting an abnormal state of the inverter, and a driver controller for controlling a normal operation or shutdown of the driver.

Abstract: An electronic high frequency supply, such as lamp ballast, includes a double rectifier, two storage Capacitors in series, and an isolating inductor between rectifier and an AC input. Each storage capacitor is charged to a voltage greater than peak of the AC input. An inverter is connected to the storage capacitors, and has a high frequency inductive load circuit connected between inverter output and a junction between the isolating inductor and double rectifier. A capacitor, connected from the junction to the junction of two storage capacitors, forms a high frequency resonance circuit with the inductive load circuit. Current is drawn from the input AC only as a series of pulses at the inverter frequency. The isolating inductor filters out the high frequency part of the current pulse and makes the input current near sine wave.

Abstract: A low cost DC-DC converter facilitates a reduction of the switching loss in the wide, variable range of the continuity ratio for a main switching device. The DC-DC converter includes a direct current source, an ON-OFF-controllable main switching device, a main coil which is series connected to the main switching device, a fly-wheel diode which is arranged such that the induction current of the main coil flows when the main switching device is shifted into the OFF state, and a smoothing capacitor for smoothing the output of the main coil, Also included is an auxiliary transformer with a primary winding as a direct current source and a secondary winding. The main switching device and the auxiliary switching device are controlled such that they are shifted alternatively into the ON state, and the main switching device, is shifted into the ON state a given time after the auxiliary switching device has been shifted into the OFF state.

Abstract: An inverter for providing power to a lamp coupled to a power supply and a lamp circuit. The inverter can selectively provide the lamp circuit with AC voltages of two different frequencies. The inverter includes: a first switch for passing a DC voltage; a first and second oscillating circuit coupled to the first switch that receives DC voltage and respectively generates a first AC voltage having a first frequency and a second AC voltage having a second frequency; and a transformer coupled to the first oscillating circuit and the second oscillator for transforming the first AC voltage provided by the first oscillating circuit or the second AC voltage provided by the second oscillator into a third AC voltage and passing the third AC voltage to the lamp circuit. The first switch serves to selectively pass the DC voltage to the first oscillating circuit or the second oscillating circuit.

Abstract: A controlling device for use with an exterior landscape lighting assembly. The lighting assembly includes a transformer having an input line connected to an electrical power source. The transformer converts a primary electrical load to a secondary electrical load which is in turn outputted though an output line connecting to a plurality of individual lighting units. The controlling device is capable of being mounted at an appropriate location indoors or outdoors. An enclosure unit includes a power supply circuit, a switch, a relay and control circuitry. The power supply circuit converts the secondary transformer output to a filtered direct current suitable for powering the control circuitry. The control circuitry interfaces with remote momentary switches and alternately activates and deactivates the lighting units. The control circuitry further includes an optional receiver for wireless operation. The controlling device can be incorporated into the transformer assembly.

Abstract: A lamp inverter with continuous strike voltage facilitates faster striking of a fluorescent lamp, especially at cold temperatures. A frequency sweep generator sweeps the frequency of the lamp inverter to a striking frequency corresponding to a striking lamp voltage and then maintains the striking frequency until the lamp strikes.

Abstract: A ballast for electrical lighting fixtures has improved thermal protection features. The ballast has ballast laminations, primary and secondary coils, and a thermal protector, the thermal protector being wired in series with the secondary coil. When the ballast is of the type having multiple input voltage taps on the primary coil, the electrical positioning of the thermal protector in series with the secondary coil causes the wiring assembly of the thermal protector (as part of the ballast) to be independent of the primary coil input voltage tap used in a particular application. Improved electrical lighting circuits for high-intensity-discharge lamps may be obtained, the circuits having the above-described thermally-protected ballasts.