Abstract: To provide for automatic disconnect upon failure of a filament of one (E2) f the electrodes of a fluorescent lamp, an output terminal (P1) of a power rectifier is connected through the filament to a supply terminal (P3) of a push-pull frequency generator formed by two transistors (T1, T2). The fluorescent lamp (LP) has its other electrode (E1) connected to a common terminal between two transistors (T1, T2) of the high-frequency generator. A series resonance circuit (L1, C6, C8) is capacitor-coupled (C7) to the lamp. Upon failure of the filament of the first electrode (E2), or removal of the lamp from its lamp sockets, power supply to the transistor oscillator or frequency generator circuit is interrupted, so that the oscillator is deenergized; upon insertion of an operative lamp in the lamp circuit, the circuit is closed so that the fluorescent lamp is automatically started by the push-pull oscillator (3) formed by the two transistors (T1, T2) and associated circuitry.

Abstract: A system for lighting fluorescent lamps, includes a plurality of fluorescent lamps, a transformer for generating filament voltage and a starting voltage for the fluorescent lamps, a switching circuit for sequentially and periodically opening and closing a plurality of its contacts and a driving circuit for electrically biasing the transformer and the switching circuit. A starting voltage is sequentially applied to the fluorescent lamps which are each independently connected to one of the contacts so that the fluorescent lamps may be sequentially turned on.

Abstract: The inventive power supply converts the low-frequency alternating current source into high-voltage direct current. An induction windings network series connected to the fluorescent tube provides a feedback signal to a pair of bridging transistors which then respectively alternates to be on or off to output a high-frequency, high-voltage signal for the tube to use. The network is connected so that the inductors provide the feedback signal, the signal having a resonant frequency suitable for activating the tube. The light emitted in accordance with this invention is continuous, due to the inventive feedback, in comparison to the light emitted by a fluorescent tube utilizing a transformer and a starter.

Abstract: A starting and operating circuit for a discharge lamp in which the ballast reactance includes first, second and third coil segments with the third coil segment compromising part of the ignitor circuit and being electrically connected between the first and second coil segments.

Abstract: A self-oscillating half-bridge inverter is powered from a power-line-operated DC voltage source and has a series-tuned high-Q LC circuit connected across its output. A pair of fluorescent lamps is series-connected across the tank capacitor of the LC circuit. An EMI filter is positioned between the inverter and the power line, thereby to minimize electro-magnetic interference. This same EMI filter also acts to produce a control signal in case a ground fault current were to occur; which control signal is used for preventing the magnitude of the ground-fault current from exceeding acceptable limits.

Abstract: Apparatus for use with a fluorescent light dimming circuit to delay the application of power to the lamp for a first time period sufficient to allow the electronic components to stabilize and thereafter to delay any dimming signal to the lamp and, instead, apply full power to the lamp for a time period sufficient to allow the filament of the lamp to warm up.

Abstract: An electronic ballast circuit is provided for starting, operating and controlling the brightness of one or more fluorescent lamps. The brightness of the lamps is controlled over the full range of brightness from zero to full-rated power. The circuit power factor is controllable, and is preferably operated at a relatively high leading power factor. The circuit includes a capacitive ballast working in conjunction with a gapped transformer so as to provide the high leading power factor while, at the same time, maintaining stable and uniform brightness of the lamps. A power field effect transistor is utilized to function as a current stabilizer in conjunction with the capacitive ballast and gapped transformer. The system incorporates a dimming control circuit for increasing and decreasing the brightness of the lamps.

Abstract: A DC/AC converter for igniting and supplying a gas discharge lamp (1) has two input terminals (C, D) intended to be connected to a DC voltage source. These input terminals are connected together by means of a series arrangement of a load circuit comprising at least the discharge lamp (1) and an induction coil (8), as well as a first semiconductor switching element (9). This load circuit being shunted by a circuit comprising a second semiconductor switching element (10). The switching elements (9, 10) are rendered alternately conductive and non conductive at a high frequency. The lamp is shunted by a third semiconductor switching element (12) which is conductive while the lamp electrodes (2, 3) are being pre-heated, whereafter the converter is rendered inoperative for a short period of time in order to ignite the lamp, which time is shorter than the time required to cool the lamp electrodes to below their emission temperature. The converter is thereafter rendered operative again.

Abstract: A self-oscillating inverter-type fluorescent lamp ballast has two modes of operation: (a) a first mode in which the inversion frequency is about 70 kHz and is resonant with a first tuned circuit by which power is supplied to the cathodes of the fluorescent lamp; and (b) a second mode in which the inversion frequency is about 30 kHz and is resonant with a second tuned circuit by which main lamp power is supplied. When the ballast is initially powered-up, it starts operation in its first mode, thereby providing cathode heating power without yet providing main lamp power. About one second later, after the cathodes have reached full incandescence, the inverter automatically changes into its second mode, thereby providing main lamp power while at the same time removing cathode heating power. If for some reason the lamp were not to ignite within about 10 milli-seconds, the inverter reverts back into its first mode; thereafter cycling between its two modes until the lamp does ignite.

Abstract: In a method or combination, a DC voltage supply, a converter including a series or a parallel resonant circuit for converting the DC voltage to a sinusoidal current, and a load including at least one fluorescent lamp responsive to the sinusoidal current to effect excitation of the lamp.

Abstract: This ballast system for a gaseous discharge lamp comprises a reactor coil and core structure forming a magnetic circuit for flux developed by power-frequency current through the coil during lamp operation. The core comprises a leg surrounded by the reactor coil, two yokes at opposite ends of the leg, and flux-return structure connected between the two yokes radially outside the coil. For developing a high-voltage, high-frequency pulse for initiating lamp operation, there is provided an ignitor coil surrounding the flux-return structure and the reactor coil and inductively coupled to the reactor coil with respect to high-frequency pulse components.

Abstract: A portable high pressure sodium lamp lighting system is mounted on a mobile cart, the cart carrying a mobile power supply in the form of an automotive type battery. The portable lighting system employs a standard high pressure sodium luminaire designed to be driven by 115 volt 60 cycle utility generated power. A DC to AC converter is employed which converts the DC battery supply to a 115 volt simulated 60 cycle supply. The AC characteristic is simulated by generating a quasi-square wave form which approximates a 60 cycle characteristic when driving the luminaire.

Abstract: A discharge lamp lighting system including at least one switch device connected between a d.c. power supply and a discharge lamp which is turned on by a high frequency power generated through turning-on and -off of the switching device. In the discharge lighting system, the discharge lamp lighting operation is allowed to start when the d.c. power supply voltage reaches a predetermined voltage value A or over, and the discharge lamp lighting operation is stopped when the d.c. power supply voltage lowers smaller than a predetermined voltage value B, where the values A and B take a relation that B is smaller than A.

Abstract: A ballast circuit for a fluorescent light bulb of the type having an elongated envelope with an electrode at each end. The ballast circuit includes a square wave generator which generates a square wave in excess of 10,000 hertz. The output from the square wave generator is used to modulate a voltage from a power source having a voltage in the range of 400-800 volts so that the modulated voltage has a frequency equal to the square wave frequency. The resulting modulated voltage is then electrically connected to the electrodes of the fluorescent lamp which illuminates the lamp.

Abstract: An electronic ballast provides a high-frequency current-limited voltage between a first socket terminal and a second socket terminal. These socket terminals are adapted to receive and hold a rapid-start fluorescent lamp. The first terminal has a relatively low-magnitude potential with respect to ground; the second terminal has a relatively high-magnitude potential with respect to ground. A person coming in direct or indirect contact with the second terminal is apt to receive a hazardous electric shock. A self-oscillating electronic inverter is operable to provide the high-frequency voltage. To provide an output, this inverter has to be triggered into oscillation. However, if no current flows from the first terminal, the inverter will automatically become disabled with 25 milli-seconds; whereafter it will not be re-triggered for about 1.5 seconds.

Abstract: A full-bridge transistor inverter is connected at its DC supply-side with an energy-storing capacitor. The inverter's output terminals are connected in series between a source of AC voltage and a load; which load may be an electric motor, a fluorescent lighting system, etc. By controllably switching the transistors of the inverter ON and OFF in synchronism with the frequency of the AC voltage, effective control of the flow of power between the AC source and the load is achieved. DC voltage on the energy-storing capacitor is obtained from the AC source by way of the timing of the switching action of the inverter.Hence, in contrast with the ordinary situation where an inverter is supplied with net power from its source of DC voltage and where this net power is then supplied to a load connected with the inverter's output, the present invention relates to a situation where no net power is supplied to the inverter from its source of DC voltage and where no net power is supplied from the inverter's output.

Abstract: A=n apparatus is provided for controlling the charging of a main capacitor of a flash unit. Comparison means detect the timing at which a voltage V across the main capacitor reaches a reference voltage V.sub.1, at which point a flash photograph can be taken. A timer detects whether a predetermined time period has elapsed since the voltage V across the main capacitor reached the reference voltage V.sub.1 so as to stop charging the main capacitor. When the voltage V across the main capacitor drops to the reference voltage V.sub.1, as a result of the phenomenon known as "spontaneous discharge", recharging of the main capacitor occurs and the above process is repeated. When the recharging of the main capacitor has been performed over a predetermined time period or a predetermined number of times, the charging of the main capacitor is stopped.

Abstract: A diming circuit for a hot cathode fluorescent lamp is operated in a push-pull mode whereby the hot filaments are alternately the cathode and the anode. Both filaments thus experience similar degradation with time at all brightness levels, thereby enhancing and lengthening the life of the lamp.

Abstract: Arc discharge lamps driven at frequencies in excess of 20 kHz may exhibit the phenomenon of `acoustic resonance` in which longitudinal and lateral acoustic waves are supported in the arc tube. This is a problem because the acoustic wave may give rise to an instability in the discharge arc, causing it to stretch or gyrate and invariably to extinguish. In some cases damage may be caused to the arc tube. A power supply suitable for an arc discharge lamp comprises a drive circuit arranged to supply voltage to the lamp and control means for causing a characteristic of the voltage to vary, with time, in accordance with a pseudo random sequence in order to reduce, or eliminate, acoustic resonance in the lamp.

Abstract: An improved, more energy efficient reactor-type ballasting circuit for fluorescent lamps includes an inductive ballasting coil for directly applying an AC line voltage to the cathodes of a lamp without an intermediate autotransformer and also includes a glow type thermal switch in series with a positive temperature coefficient (PTC) resistor for electrical connection across the cathodes of the lamp to conduct pre-heating current to the lamp cathodes. The PTC resistor will effectively remove the glow switch from the ballast circuit if the switch fails to open after an appropriate time delay.

Abstract: A controller for a gas discharge lamp supplies the lamp with a direct current which has been pulse-width modulated at a high frequency via a smoothing circuit and a polarity inversion circuit. The polarity inversion circuit periodically reverses the polarity of current supplied to the lamp to equalize electrode wear in the lamp. The controller senses the lamp voltage, current, power or other characteristics and maintains at least one operating parameter of the lamp, for example the lamp current, constant. A warm up cycle allows this parameter to be adjusted for fast starting of the lamp.

Abstract: An electronic transformer system for powering gaseous discharge lamps includes an output transformer having a load connected to a secondary winding and having a power storage capacitor connected in series with a primary winding, a charging transistor connecting one end of the series combination to one polarity terminal of a voltage doubler DC power source, the other end of the series combination connected to the other polarity terminal of the power source, a discharging transistor connected across the series connected primary and capacitor, and an oscillator connected through a coupling transformer to the bases of the transistors. The oscillators alternately causes the transistors to switch into conduction to thereby alternately cause the charging and discharging of the capacitor through the output transformer. The charging and discharging characteristics of the capacitor result in the turn off of the transistors occurring at low current levels whereby turn off of the transistors is accelerated.

Abstract: A discharge tube opening circuit for varying tube intensity at regular intervals without flicker between an illuminated and an unilluminated state. Combinations of tubes controlled by respective circuits give rise to novel display arrangements through choice of tube colors and particular sequences of variation of luminous intensity.

Abstract: A light adjusting apparatus comprising a lamp connected to a commercial a.c. power supply via a triac, and a switching control circuit operable by a direct current obtained by directly rectifying the current of the power supply for controlling the conduction timing of the triac based on the zero-cross timing of the power supply. The conduction timing of the triac is controlled by a signal obtained by producing a pulse-width modulated light adjusting signal from a signal generating circuit by a light-emitting element, causing a photodetector in the control circuit to receive the adjusting signal and subjecting the resulting output of the control circuit to pulse-width demodulation.

Abstract: Lamp operating voltage levels are reduced by using a boost circuit to initiate a triggering sequence in one of two lamps connected in series. The boost circuit is connected across one of the lamps at a connector point common to the two lamps. In a preferred embodiment, trigger pulses are applied sequentially to each lamp, the boost circuit voltage contained in an associated capacitor is discharged through the first triggered lamp, causing it to begin conduction. Most of the voltage from a main storage capacitor then becomes available to break down the second lamp.

Abstract: A ballasting system for powering an array of multiple parallel-oriented fluorescent lamps in a sun tanning apparatus comprises and an electronic frequency converter adapted to convert ordinary 60 Hz power line voltage into a 350 Volt/30 Hz sinusoidal voltage provided between a pair of bus conductors and suitable for directly powering each fluorescent lamp by way of a simple capacitive or inductive current-limiting reactance means. The fluorescent lamp cathodes are heated by way of individual transformers, with one transformer for each pair of lamp cathodes. Only two pairs of distribution conductors are required for powering the complete array of mutually parallel-disposed fluorescent lamp pairs regardless of the number of lamps involved, with one pair running along the one side of the array, and the other pair running along the other side of the array. Of each pair of fluorescent lamps, one lamp is powered by way of an inductive reactance means and one lamp is powered by way of a capacitive reactance means.

Abstract: A high frequency dimming ballast dims to about 1 percent of rated output in a repeatable way so that parallel connected dimming ballasts will all produce the same light illumination when dimmed to a very low percentage of their rated light output. A first current sensor is connected in series with a semiconductor power switching device which is coupled to and controls power to the ballast. A second current sensor is connected directly to the lamp circuit to detect actual lamp current, particularly at low illumination conditions, for example at less than 10 percent of the rated light output. Lamp control under low illumination conditions is derived from the lamp current sensor and overrides control by the sensor in series with the transistor switch means.

Abstract: A heavy duty flasher for incandescent lamps for a motor coach or the like incorporates a pair of power MOSFETs in parallel for efficient, cool operation and includes a pair of timers, one for flash rate control and the other for producing AC for operating a voltage multiplier to provide gate voltage for the MOSFETs. Protective circuitry senses current overload and terminates current flow to protect the power devices while allowing inrush current to the lamps at the beginning of each cycle. A circuit sensitive to the presence of load supplies power to the timers only under load conditions.

Abstract: An electronic ballast provides a high-frequency current-limited voltage between a pair of socket terminals. These socket terminals are adapted to receive and hold a rapid-start fluorescent lamp. A person coming in direct or indirect contact with one of these terminals may receive a hazardous electric shock.A self-oscillating electronic inverter is operable to provide the high-frequency voltage. To provide an output, this inverter has to be triggered into oscillation. However, except if current flows into both socket terminals, the inverter will automatically become disabled within 25 milli-seconds; whereafter it will not be re-triggered for about 1.5 seconds.With no current flowing, the magnitude of the high-frequency AC voltage is high enough to permit proper starting of a the rapid-start fluorescent lamp within a time span of 25 milli-seconds, but only after its cathodes have become incandescent. As soon as the lamp has started, lamp current flows into the socket terminals and through the fluorescent lamp.

Abstract: A fluorescent lamp operating system for a skin treatment apparatus comprises: (i) a plurality of pairs of fluorescent lamps for providing luminous radiation, each pair of lamps being adapted to be powered from 30 kHz/120 Volt by way of a high-Q series-resonant L-C ballasting circuit; (ii) a relatively low-power frequency converter connected with the power line and operable to provide power for heating the cathodes in these fluorescent lamps, thereby conditioning the lamps for easy starting; (iii) a relatively high-power frequency converter also connected with a power line and operable to provide the 30 kHz/120 Volt required for operating the plurality of pairs of fluorescent lamps by way of the high-Q series-resonant L-C ballasting circuit; and (iv) delay means operable to prevent the 30 kHz/120 Volt provided by the high-power frequency converter from being applied to the fluorescent lamps until after power has been applied to heat the lamp cathodes for at least one second.

Abstract: A lamp start, hot-restart and operating circuit for a high wattage, high intensity discharge lamp includes cascaded resonant circuits with capacitors and series-connected inductors connected to an AC source. A pulse circuit including two pulse transformers supplies streamer-forming current, the secondary windings of the pulse transformers being connected in series with the lamp. When the lamp commences normal operation, the operating current energizes a relay to remove the capacitors and pulse circuit from the operating circuit, allowing the inductor to function as the lamp ballast.

Abstract: An operating system for a sun tanning apparatus comprises an array of multiple parallel-oriented fluorescent lamps and an electronic frequency converter adapted to convert ordinary 60 Hz power line voltage into a 350 Volt/30 kHz sinusoidal voltage provided between a pair of bus conductors and suitable for directly powering each fluorescent lamp by way of a simple capacitive or inductive current-limiting reactance means. The fluorescent lamp cathodes are heated by way of individual transformers, with one transformer for each pair of lamp cathodes. Only two pairs of conductors are required for powering the complete array of mutually parallel-disposed fluorescent lamp pairs regardless of the number of lamps involved, with one pair running along the one side of the array, and the other pair running along the other side of the array. Of each pair of fluorescent lamps, one lamp is powered by way of an inductive reactance means and one lamp is powered by way of a capacitive reactance means.

Abstract: An emergency lighting unit comprises a battery-powered converter circuit for maintaining a discharge in a gas discharge or fluorescent light, the converter circuit also being arranged to generate a high voltage for striking the discharge in the light. When the mains supply is good and a switch is closed for turning on the light, the converter circuit is activated to provide its high voltage for striking the discharge, after which the discharge is maintained from the mains supply. If the mains should then fail, the converter circuit provides its low voltage from its battery to maintain the discharge. If the mains fails while the light is switched off, the converter circuit strikes and then maintains the discharge in the light.

Abstract: A DC-AC converter for supplying energy to a dishcarge lamp (17). The converter is in the form of an imcomplete half-bridge circuit (11, 12; 15, 16, 19, 18). The lamp (17) is connected in series with a coil (18) and a capacitor (16). Two switching elements (11, 12) in the half-bridge circuit are formed as semiconductor switching elements. The lamp current is a square-shaped alternating current. A diode (13) is connected in parallel with the one switching element (11) and a diode (14) is connected in parallel with the other switching element (12). The control circuit of the switching elements is provided with a switching circuit (21) which alternately switches the one switching element (11) and the other switching element (12) several times. The number of switching elements through which the lamp current flows can therefore remain limited to two.

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: An improved ballast (10) that operates an ionic conduction lamp (40) such as a conventional phosphor coated fluorescent lamp. The ballast (10) comprises an ac/dc converter that converts an a-c power signal to a d-c power signal that drives a transistor tuned-collector oscillator (30). The oscillator is comprised of a high-frequency wave-shape generator (32) that in combination with a resonant tank circuit (36) produces a high-frequency signal that is equivalent to the resonant ionic frequency of the phosphor. When the lamp (40) is subjected to the high frequency, the phosphor is excited which causes a molecular movement that allows the lamp (40) to fluoresce and emit a fluorescent light. By using this lighting technique, the hot cathode of the lamp, which normally produces a thermionic emission, is used only as a frequency radiator. Therefore, if the cathode were to open, it would have no effect on the operation of the lamp. Thus, the useful life of the lamp is greatly increased.

Abstract: An electronic ballast powers fluorescent lamps in a lighting fixture with a current of magnitude related to the frequency of the ballast output voltage. The ballast comprises self-oscillating inverter means wherein the frequency of oscillation can be influenced by receipt of a control signal at a control input connected in circuit with the inverter's positive feedback circuit. The ballast also comprises optical sensor means so positioned and constituted as to sense the light level within the lighting fixture and to provide a control signal commensurate with the light level. This control signal is then applied to the control input in such manner as to regulate the inverter frequency as a function of the light level, thereby correspondingly to regulate the magnitude of the current fed to the fluorescent lamps.

Abstract: To permit dimming of a halogen incandescant lamp, or set of lamps connected to an electronic transformer circuit which receives operating voltage from a power network, rectifies the current supply and chops the rectified power to provide high-frequency alternating voltage for transformation to low voltage of the incandesent lamp, a non-current compensated choke having an inductance of at least 50 mH is connected in series between the rectifier output terminals and the rectifier system terminals, an oscillation start acceleration circuit including a CR circuit is connected in parallel with the starting circuit for the alternately operating transistors and a pair of symmetry resistors (R6,R7) are connected in parallel to symmetry defining capacitors (C6,C7), connected across the rectifier output terminals and a mid-point (M) of the oscillation transistors.

Abstract: A fluorescent lamp is mounted on an ordinary Edison-type screw-base; which screw-base contains a frequency-converting electronic ballast. The combined lamp-ballast-assembly is adapted to be used in an ordinary screw-in lamp socket powered from ordinary 120 Volt/60 Hz power line voltage. The frequency-converting ballast within the screw-base converts the 120 Volt/60 Hz power line voltage to a high-frequency (20-30 kHz) substantially sinusoidal current, which is then used for powering the compact fluorescent lamp.

Abstract: Disclosed is a novel switching circuit directed to use for limiting surge into lamp, comprising a diode circuit wherein two sets of diodes are connected in reverse-parallel; a resistive element connected in series with a lamp to limit the switch-on surge thereinto; a bidirectionally conductive element having a main current path connected in seried with an ac source through said resistive element, diode circuit and lamp; and a timing circuit having a time constant, said timing circuit triggering said bidirectionally conductive element with the voltage across said diode circuit to short-circuit said resistive element after a lapse of said time constant from switch-on.

Abstract: A high frequency system for gas discharge lamps includes a method of, and apparatus for, controlling the operation of a plurality of gas discharge lamps and provides; a reduction in starting and operating voltage and current; an increased range of dimming; and improved efficiency and reliability.

Abstract: To reduce network harmonics upon connecting a fluorescent lamp (LP1) with a power network rectifier (2) and a push-pull frequency generator (3) and a series resonance circuit (4) to the network, a harmonic filter is connected in the circuit with the fluorescent lamp (LP1) or lamps (LP1, LP2). The harmonic filter includes two diodes (D8, D9), connected in forward current passing direction to the power rectifier (2), and two capacitors (C7, C8) connected, respectively, between the serially connected diodes and a center tap (M1) between the push-pull transistors directly and beyond an inductance forming part of a series resonance circuit (4) for the lamps. In parallel to the two diodes, two further diodes (D10, D11) are provided, having a center tap (M4) which is connected over a capacitor (C9) also to the center tap between the transistors of the push-pull frequency generator (3). Preferably, the capacity value of the further capacitor (C9) is about 0.

Abstract: An integrated lighting device includes a housing having a long-life light source electrically hardwired directly to a source of electrical energy. The housing is mechanically connected to the electrical box or the architectural surface surrounding the source of electrical energy. Electrical energy modifying elements, such as ballast, are hardwired between the electrical energy source and the light source. The entirety of the lighting device is therefore disposable at the end of the useful life of the light source.

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 device and process for the generation of ozone using an ozone generator having two electrodes connected across the secondary winding of a high voltage transformer, the primary winding of which is connected to a converter which supplies thereto a square wave current of variable amplitude and variable frequency. A compensation coil is connected across either the primary winding or the secondary winding of the transformer. The ozone generator includes a solid dielectric and a gas path between its two electrodes. The inductance of the compensating choke and the operating frequency of the converter are selected such that the resonance frequency of the resonant circuit formed by the ozone generator and the compensation choke lies below the operating frequency of the converter current supply in any operating condition.

Abstract: An electronic ballast or energizing circuit for a fluorescent lamp is disclosed. A rectified supply voltage is applied through an electronic switch to a fluorescent lamp through a current sensing resistor. A switching regulator produces a pulse width modulated pulse train which is applied to the electronic switch for supplying a pulsed voltage across a smoothing filter to the fluorescent lamp. The pulse width output of the switching regulator is modulated in accordance with the voltage across the sensing resistor for maintaining the current drawn by the lamp at a substantially constant value.

Abstract: An illuminator for cultivating a plant by a discharge lamp excited by the output of a high frequency power source by utilizing photosynthetic mechanism. The output power of the high frequency power source is controlled to high and low powers by a bright and dark controller to alternatively supply the high and low powers to the discharge lamp in predetermined periods.

Abstract: A fluorescent lamp operating device having a power supply, a circuit for converting the output power from the power supply into a high-frequency power, a lighting circuit connected to a secondary side of a transformer of the high-frequency power converter circuit to light a fluorescent lamp, a circuit for preheating the filament of the fluorescent lamp, a switch circuit including diodes and at least one transistor connected in series with the fluorescent lamp in the lighting circuit, and a control circuit for turning off the transistor for a predetermined period when the power supply is turned on thereby turning off the lighting circuit to actuate the preheating circuit during this period. The control circuit turns on the transistor at the end of the predetermined period to thereby actuate the lighting circuit.

Abstract: Apparatus for sequentially igniting and serially operating a pair of electric discharge lamps from a source of AC supply voltage. The apparatus includes a transformer with a primary winding and first and second secondary windings mounted on a magnetic core having a slot under the second secondary winding. The first secondary winding has a high leakage reactance and the windings are serially connected with the secondary windings wound in opposition to one another. First and second capacitors are connected in series with the first and second lamps, respectively, to prevent the flow of DC current therethrough. By a novel choice of the ratios of the capacitance values of the second capacitor to the first capacitor and of the slot dimensions, superior operating characteristics for the apparatus are achieved.

Abstract: A load is provided, at all times when in operation, with a D.C. voltage having at least a minimum holding magnitude by: providing a source voltage having a peak magnitude greater than the holding magnitude; connecting the source voltage to the load only while the source voltage magnitude is greater than a preselected magnitude; charging from the peak source voltage magnitude an energy storage element while the load is connnected to the source voltage; energizing the load from the charged energy storage element whenever the source voltage magnitude is less than the preselected magnitude; increasing the effective impedance of the load whenever the load is energized by the storage element; and selecting the energy storage element to provide at least the holding voltage to the load during each time interval when the energy storage element is connected to the load.