Abstract: A full-bridge inverter comprises two pairs of switching transistors and is conditionally operable to self-oscillate in either of two modes: a first mode wherein one of the two pairs of switching transistors self-oscillates in manner of a half-bridge inverter and powers a first load, and a second mode wherein both pairs of transistors self-oscillate in manner of a full-bridge inverter and then powers a second load in addition to the first load.Such a dual-mode inverter has utility in situations where a load has to be pre-conditioned with a relatively small amount of conditioning power (such as cathode heating power) before being ready to absorb its main operating power. Typical examples of such loads are magnetrons and fluorescent lamps.

Abstract: With the AC voltage output from an inverter series-driving a high-Q parallel-loaded resonant L-C circuit, and with the parallel-connected load being of a type that needs to be conditioned before it will absorb power (as would be the case with loads such as magnetrons or fluorescent lamps), the inverter and/or the L-C circuit may be destructively overloaded during the time it takes for the load to become conditioned.In a power-line-operated inverter-type power supply with such a high-Q parallel-loaded resonant L-C circuit series-connected across its output, subject invention provides for means to prevent such destructive overload. In this power supply, the unfiltered pulsed DC output of a full-wave power-line-supplied rectifier is applied to a pair of inverters: an auxiliary inverter for pre-conditioning the load, and a main inverter for powering the load.

Abstract: Center-tapped DC power to a self-oscillating full-bridge inverter-type fluorescent lamp ballast is obtained from a regular power line by way of a voltage doubler. The DC power is supplied to the inverter through an inductor means having two separate windings on a common magnetic core--with one winding being positioned in each leg of the DC power supply. The full-bridge inverter, which comprises four switching transistors connected in usual full-bridge fashion, comprises a center-tapped parallel-tuned L-C circuit connected across its AC output, thereby providing a center-tapped sinusoidal voltage to its load, which consists of a fluorescent lamp connected in series with a current-limiting capacitor. Due to the effect of the inductor means, the current provided to the bridge is substantially constant during a complete period of the inverter's oscillation.

Abstract: A battery charger comprises a self-oscillating inverter with saturable transformer means in its positive feedback circuit. The saturation flux density of the magnetic material used in this saturable transformer means determines the frequency of inverter oscillation. A permanent magnet is rotatably mounted adjacent the saturable transformer means and is used by way of cross-magnetization to adjustably affect the saturation flux density of the magnetic material, thereby correspondingly to adjust the frequency of oscillation: the more cross-magnetizing flux provided to the magnetic material from the permanent magnet, the smaller the saturation flux density and the higher the frequency of oscillation.The battery charging current is attained from the inverter's squarewave voltage output by way of a series-excited parallel-loaded tuned L-C circuit, thereby providing for a battery charging current of magnitude dependent upon the frequency of inverter oscillation.

Abstract: Subject track lighting system comprises a more-or-less regular lighting track having at least two pairs of track conductors. Of these track conductors, an initial pair carries the regular 120 Volt/60 Hz power line voltage. Plugged into the track and connecting with the initial pair of track conductors is one or more voltage-conditioning adapters--with each such adapter receiving its input voltage from the initial pair of track conductors and providing its conditioned output voltage to one of the other pairs of track conductors. Thus, depending upon the particular functions provided by the adapters, the different pairs of track conductors may be used in independently different ways. For instance, with one adapter being a frequency converter with an output voltage of 12 Volt/30 kHz, the pair of track conductors to which its output is connected may be used directly with low-voltage Halogen lamps--while ordinary 120 Volt incandescent lamps may simultaneously be used with the initial pair of track conductors.

Abstract: In a power-line-operated inverter-type power supply for the magnetron in a microwave oven, power is provided to the magnetron from the inverter by way of a series-excited resonant LC circuit, the magnetron load being connected in parallel with the tank capacitor of this L-C circuit. This arrangement provides for good matching between the output characteristics of the inverter and the operating characteristics of the magnetron. To prevent potentially destructive overload of the inverter, as may occur if the inverter's output voltage is series-applied to the resonant L-C circuit before the magnetron is ready to absorb power, inverter oscillation is not initiated until after the magnetron cathode has been heated to incandescence.

Abstract: High-efficiency inverter circuits, particularly half-bridge devices, are especially suitable for energizing gas discharge lamps. The inverters preferably employ a series-connected combination of an inductor and a capacitor to be energized upon periodic transistor conduction. Transistor drive current is preferably provided through the use of at least one saturable inductor to control the transistor inversion frequency to be equal to or higher than the natural resonant frequency of the inductor and capacitor combination. The inverters can develop high output voltages to supply external loads connected to the inductor-capacitor combinations.

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: In a power-line-operated electronic inverter-type power supply for the magnetron in a microwave oven, the unfiltered pulsed DC output of a full-wave rectifier is applied to a bridge inverter, the output of which is a 30 kHz squarewave voltage pulse-amplitude-modulated at 120 Hz. By way of a step-up voltage transformer, this 30 kHz output voltage is applied to a high-Q series-resonant L-C circuit. The Q-multiplied voltage developing across the tank capacitor of this L-C circuit is then rectified and filtered for 30 kHz ripple-voltage. The output resulting from this high-frequency rectification is a 120 Hz pulse-amplitude-modulated current-limited DC voltage suitable for direct application to the magnetron. The bridge inverter has to be triggered into oscillation; which oscillation ceases each time the magnitude of the inverter DC supply voltage decreases below a given threshold level.

Abstract: In a series-resonant-loaded inverter-type electronic ballast for two rapid-start fluorescent lamps, in order to meet requirements for safety from electric shock hazard, as well as to protect the inverter circuit from over-load, means are provided by which the proper connection to the ballast of the fluorescent lamps is sensed by way of detecting the proper flow of lamp cathode heating currents. Then, after the circuit is initially turned on and if one of the lamp cathodes were to draw substantially less current than normally called for, the inverter circuit is shut down immediately. On the other hand, if each lamp cathode draws the expected amount of cathode heating current, the inverter circuit is not shut down immediately, but is allowed to operate for a time at least long enough to permit proper starting of the rapid-start fluorescent lamps.

Abstract: Subject power-limited lighting system consists of the following principal component parts: (a) a number of power-line-operated power supplies, each such power supply having a plurality of individual output receptacles, with each output receptacle being limited in terms of maximum voltage, current and power in such a way as to be classified as a Class-3 circuit according to the National Electrical Code; (b) for each power supply, a plurality of lighting units, each such lighting unit comprising one or more lamps (H.I.D.

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 source of 120 Volt/60 Hz power line voltage is full-wave-rectified and yields an unfiltered DC voltage pulsed at 120 Hz rate. This pulsed DC voltage is applied to an inverter of a type that must be triggered into oscillation. At the beginning of each of the DC voltage pulses, the inverter is triggered into oscillation; and at the end of each of the DC voltage pulses, the inverter ceases to oscillate frm lack of adequate voltage to sustain oscillation.The output of the inverter is a 30 kHz squarewave voltage amplitude modulated at the 120 Hz rate. Across the inverter output is connected a high-Q series L-C circuit resonant at about 30 kHz. A fluorescent lamp is connected in parallel with the tank capacitor of the L-C circuit.

Abstract: A lighting system for a suspended ceiling comprises a central high-frequency power source feeding a plurality of power conditioning units permanently wired-in and mounted in various locations on the permanent ceiling above the suspended ceiling. Each such power conditioning unit provides a power-limited Class-3 high-frequency voltage at an output receptacle and is operable to power a special fluorescent lighting fixture by way of a light-weight flexible two-wire detachable connect cord. Special fluorescent lighting fixtures are mounted in the suspended ceiling, with each such lighting fixture being powered from a power conditioning unit mounted somewhere nearby on the permanent ceiling above.

Abstract: A programmable quartz clock has an actuator means operable to engage with and to actuate a control lever of a mechanically actuatable entity, such as a slide switch or a wall switch, thereby to effect programmed actuation of this entity.The clock comprises a small battery, a miniature electric motor with a gear/linkage mechanism operable to engage with and to move said lever, integrated circuit means, a quartz element, numeric display means, and programming means receptive of programming instructions by way of programming input keys.Once programmed by way of the input keys, the clock is operative to cause the electric motor to operate in such manner as to move the control lever in accordance with the keyed-in program. In its anticipated most common operating mode, which includes an average total of six actuations per day, the small battery will last for years before needing replacement.

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 push-pull inverter is supplied from an inductively current-limited DC voltage source by way of a center-tap on a transformer having significant inductance. This transformer inductance is parallel-coupled with a capacitance means. The inverter is made to self-oscillate through positive feedback provided by way of a saturable current transformer. The inverter frequency is determined by the saturation time of this current transformer, which saturation time is designed to be longer than the half-cycle period of the natural resonance frequency of the transformer inductance combined with the capacitance means. The resulting inverter output voltage may be described as a sequence of substantially sinusoidal half-cycles interconnected with periods of zero-magnitude voltage. By controlling the length of the saturation time, the effective magnitude of the inverter output voltage is controlled, thereby permitting control of the amount of power provided to a load connected thereto.

Abstract: A resonant L-C circuit is series-excited from an AC voltage source and intended to be parallel-loaded with a load that, for some reason or another, may be inoperative. For efficiency reasons, the unloaded circuit Q-factor may be about 50 times higher than the loaded Q-factor; which implies that, if the load were to become inoperative, the power drawn by the L-C circuit from the source, and the voltage/current magnitudes developed in the L-C circuit, would be 50 times larger than when the load is operative. To prevent unnecessary power drain and/or to avoid damage to source and/or circuit components, which damage may occur even if the L-C circuit is left unloaded for but a very brief period, a circuit protector is provided.

Abstract: Subject invention constitutes a low-voltage limited-power (Class 2) fluorescent lighting system consisting of the following principal component parts: (a) a power-line-operated inverter power supply that provides a power-line-isolated voltage output of relatively low but substantially constant magnitude (30 Volt RMS) and relatively high frequency (30 kHz); (b) electronic means for preventing the power supply current output from exceeding a pre-determined relatively modest magnitude (8 Amp RMS); (c) a number of fluorescent lighting units, each unit consisting of one or more fluorescent lamps and a corresponding high-frequency ballasting means being adapted to be operated at a high power factor from the voltage output of said power supply; and (d) a pair of conductor wires connected with the output of said power supply and adapted to permit a number of said fluorescent lighting units to be connected in parallel across said voltage output at various points along said pair of wires.

Abstract: A master power track is mounted along the periphery of a suspended ceiling. Plug-in-connected with this master track are light-weight modular power tracks serving as grid members of the suspended ceiling. The master track, which also serves as the conventional L-bar for the suspended ceiling, is provided with a relatively high frequency voltage; which voltage is then available at any point along the individual modular power tracks. The modular power tracks also serve as the T-bars of the suspended ceiling. Ceiling panels and light-weight fluorescent lighting fixtures are placed in the suspended ceiling grid structure, with each lighting fixture being plug-in-connected with one of its adjacent modular power tracks. The plug-in connection is accomplished below rather than above the ceiling; which implies that the space above the suspended ceiling may safely be used as air plenum. However, by using grooved ceiling panels and special connect means, the resulting ceiling is completely conventional in appearance.