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) push-pull inverter means operating into an LC output circuit parallel-resonant at about 30 kHz and operative to provide a 30 kHz voltage at an output that is substantially balanced with respect to ground, and (iv) means to disable the inverter in case a 30 kHz ground-fault current flows from this output. 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: A low wattage metal vapor discharge lamp starting and operating apparatus includes an inductive ballast connected to one of a pair of terminals connectable to a low voltage source, a metal vapor discharge lamp coupled to the ballast and to the other one of the pair of lamp terminals and a non-linear dielectric element shunting the discharge lamp with the ballast and non-linear dielectric element providing a potential within about 600 usec of current reversal of the source voltage in an amount sufficient to initiate operation of the discharge lamp.

Abstract: A source of high-frequency voltage is applied directly across a series-resonant L-C circuit. A fluorescent lamp and a Varistor are both connected in parallel with the capacitor of this L-C circuit. The Varistor is operative: (i) to prevent the series-resonant L-C circuit from ever overloading the voltage source, and (ii) to limit the magnitude of the voltage provided across the lamp to a level appropriate for rapid-starting thereof. When power is initially applied, the lamp's cathodes are cold and the lamp does not conduct; which implies that a significant amount of power is dissipated in the Varistor. For sake of cost-effectivity and energy conservatiion, if the lamp fails to conduct for about 25 milli-seconds, a control means provides a short circuit across the capacitor. The resulting short circuit current is used for heating the fluorescent lamp cathodes. After about 1.

Abstract: A power inverter for an electroluminescent device is disclosed which enables the electroluminescent device to be powered from a low voltage DC power source. Switching transistors convert the low voltage DC power to low voltage AC power which is subsequently increased and coupled to a resonant circuit including the electroluminescent device. Current in the resonant circuit is sampled, referenced to half the low voltage DC power, and coupled back in phase to an amplifier and switching transistors to create an oscillator which oscillates at a frequency determined by the resonant circuit.

Abstract: In a series-resonant ballast, the voltage from an AC power source is applied directly across a ballast circuit consisting of a series-combination of an inductor and a capacitor--with a gas discharge lamp connected in parallel with the capacitor. Before the lamp ignites, the series-combination is substantially resonant at the frequency of the AC source; and, by way of resonant Q-multiplication, the voltage developed across the capacitor is of much higher magnitude than that of the voltage provided directly from the power source. This Q-multiplied voltage is effective in causing lamp ignition. Once the lamp has ignited, however, the circuit is no longer resonant. Rather, due to the loading provided by the ionized lamp, the circuit has now become inductive at the frequency of the AC source; which implies that the power provided to the lamp from the source is not provided at an optimum power factor.

Abstract: A pulse network is connected to the inductive ballast of a fluorescent lamp dimmer and includes a discharge resistor in parallel with the pulse network capacitor. The resistor size is such that it will completely discharge the capacitor prior to the initiation of any phase delayed half wave voltage which is applied to the ballast.

Abstract: Starting and operating method and apparatus for discharge lamps comprises a current-limiting and rectifying means which provides at its output a low-ripple current-limited direct current. To effect lamp starting, a series-connected inductor and capacitor form a high "Q" resonant circuit with the capacitor connected across the lamp to be operated. This starting circuit connects through a blocking capacitor and charging resistor across the low-ripple source of DC. A pair of transistors which comprise an oscillator are connected emitter-to-collector across the source of DC, with the common-connected emitter and collector connected to the blocking capacitor. A drive air-core transformer has separate feedback windings in the starting and operating circuits and drive windings are associated with the transistors. A trigger diode is used to initially pulse one of the transistors which initially oscillate to generate square waves having a frequency corresponding to the resonant frequency of the starting circuit.

Abstract: To operate at least one, and preferably a plurality of fluorescent lamps, a elf-oscillating transistor push-pull switching oscillator, using two similar transistors (T1, T2), is connected to respective lamps (3, 3', 3"), with an oscillatory circuit (4, 4', 4") to operate at audio, supersonic or low high frequency, for example in the 20 kHz range. Each lamp operating circuit has an individual series resonance circuit (4, 4', 4") which includes a ballast inductance (L1, L1', L1") and a capacitor (C1, C1', C1"). For multiple operation, the respective lamp operating circuits are connected in parallel. A special starting circuit (10) and a control circuit (9a, 9b; L2, L2', L2"; L3, L3', L3") for the switching transistors insures low-loss operation.

Abstract: A circuit for starting and operating an arc lamp includes a full wave rectifier having an input connected to a source of alternating current line voltage and a pair of output terminals having a filter capacitor connected thereacross for providing a source of direct current voltage. Connected to one of the direct current terminals is a resonant charging circuit comprising a controlled rectifier switch, an inductor and a capacitor serially connected in a circuit loop. Another inductor, which may comprise the secondary winding of a starting pulse transformer, is connected between the output of the resonant circuit and one of the supply terminals for the arc lamp to provide the dual function of both averaging filter and lamp ballast. The reference terminal of the direct current source is connected to the other arc lamp supply terminal and through a back swing diode to the output of the resonant circuit.

Abstract: Circuit operating from a direct current source applies DC pulses to a high pressure sodium vapor lamp to improve the color properties of the lamp. In one embodiment, the circuit includes a charging circuit comprising a first inductor, a diode and a capacitor connected across the DC source, and a discharging circuit comprising a second inductor of lower inductance than the first inductor, a controlled thyristor switch and sodium vapor lamp connected across the capacitor, and a timing circuit for periodically turning on the switch at predetermined intervals. A third inductor and a serially connected diode are connected across the discharging circuit to prevent excessive voltage across the controlled switch and to provide for control of lamp wattage with respect to changes in lamp voltage.

Abstract: Circuit operating from a direct current source applies DC pulses to a high pressure sodium vapor lamp to improve the color rendition of the lamp. The circuit includes a first inductor, a diode and a capacitor connected across a DC source, and a second inductor, controlled thyristor switch and sodium vapor lamp connected in series across the capacitor, and a timing circuit for periodically turning on the switch at predetermined intervals. The circuit provides for charging the capacitor, commutating the controlled switch, and discharge of the capacitor to enable subsequent re-charging thereof, so as to povide the desired pulsed operation of the lamp. This mode of operating also provides for application of voltage to the lamp which is substantially higher than the supply voltage.

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

Abstract: Operating circuit for gaseous discharge lamps, such as those of metal vapor type, having a ballast device of conventional type is provided with high voltage generating means for applying high voltage starting pulses on the lamp. The circuit may be combined with an auxiliary incandescent lamp for turning the latter on for safety lighting purposes when the gaseous discharge lamp goes out. The circuit includes an induction coil in series with the gaseous discharge lamp, a controlled switch connected to a tap on the induction coil, and a charging capacitor in series with the controlled switch. When used, the incandescent lamp is connected in series with the controlled switch in parallel with the charging capacitor.