Abstract: A lighting fixture is powered from an ordinary power line and has an inverter-type ballast for powering a fluorescent lamp. This ballast comprises an inverter means whose frequency of oscillation can be influenced by receipt of a control signal at a pair of control terminals. An optical sensor is located within the fixture in such manner as to intercept part of the light emitted by the fluorescent lamp. This sensor provides a control signal proportional to the amount of light emitted by the lamp, and this control signal is applied to the ballast control terminals 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 lamp. By providing a threshold means in combination with high gain in the control loop, the fixture light level may be accurately maintained at any desired value substantially regardless of any changes in magnitude of power line voltage and/or in lamp efficacy.

Abstract: A power-line-operated half-bridge inverter is powered from a constant DC voltage and provides an AC output voltage that is--in contrast with the usual squarewave voltage--describable as being a sinusoidal waveform with the tops clipped off at some fixed magnitude; or, described differently, a waveform composed of truncated sinusoidal waves; or, described still differently, a waveform having trapezoidally shaped half-cycles. The DC voltage is derived via voltage-doubling from the power line voltage. The AC voltage is applied across the primary winding of a so-called reactance transformer, whose loosely coupled secondary winding is connected across a gas discharge lamp. The internal inductive reactance of the secondary winding constitutes a lamp ballasting means by way of limiting the magnitude of the resulting lamp current to a pre-established desired level.

Abstract: In an electronic ballast for Rapid-Start fluorescent lamps, each one of two of the four transistors in a full-bridge inverter is driven from a commercially available timer by way of simple diode-resistor parallel-combination. Each one of the other two transistors is driven directly from an auxiliary winding on the full-bridge inverter's power output transformer. The fluorescent lamps are series-connected with a current-limiting inductor to form a series-combination; which series-combination is connected across an output winding of the power output transformer. Heating voltage for each of the lamps' cathodes is obtained by way of two series-connected windings: one one the power output transformer and one on the current-limiting inductor. The magnitude of the resulting cathode heating voltage is substantially higher prior to lamp ignition as compared with after lamp ignition.

Abstract: A power-line-operated inverter-type ballast powers one or more fluorescent lamps in a lighting fixture. The ballast comprises self-oscillating inverter means wherein the frequency of oscillation can be influenced by receipt of a control signal at a pair of control terminals 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 that light level. This control signal is then applied to the control terminals 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: An electronic ballast draws current from the power line with power factor over 90% and total harmonic distortion under 20%, and powers two series-connected 48"/T-12 fluorescent lamps with a 30 kHz current having crest-factor better than 1.7. The ballast includes a power-factor-correcting up-converter and a half-bridge inverter providing a 30 kHz squarewave voltage across a series-resonant high-Q L-C circuit. When the L-C circuit is not loaded, the magnitude of the 30 kHz voltage developing across its tank capacitor is clamped by non-dissipative means to a peak-to-peak magnitude equal to the magnitude of the inverter's DC supply voltage. The ballast output voltage consists of the sum of two components: (i) the 30 kHz voltage across the tank capacitor, and (ii) a 30 kHz voltage obtained from an auxiliary winding on the tank inductor. The ballast output voltage is non-pulsing and is provided at a pair of ballast output terminals across which are series-connected the two 48"/T-12 fluorescent lamps.

Abstract: Power to a self-oscillating inverter ballast is supplied from a DC voltage source through an inductor means having two separate windings on a common magnetic core--with one winding being positioned in each leg of the power supply. The inverter is loaded by way of a parallel-tuned L-C circuit connected across the inverter's output, thereby providing a sinusoidal voltage thereat. A fluorescent lamp is connected by way of a current-limiting capacitor with the inverter's output.

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

Abstract: In an electronic ballast, a half-bridge inverter is powered from a constant DC voltage and provides an AC output voltage having a waveform with trapezoidally shaped half-cycles. This AC voltage is applied across the primary winding of a leakage transformer, whose loosely coupled secondary winding is connected across a gas discharge lamp. The internal inductive reactance of the secondary winding constitutes a lamp ballasting means by way of limiting the magnitude of the resulting lamp current to a pre-established desired level. The ballast is enclosed in a steel housing of conventional shape and size (i.e., rectangular: about 2.3" wide, 1.5" high, and 8.2" long). Significant power losses may result from magnetic coupling to the walls of the steel housing of the substantial leakage flux surrounding the leakage transformer.

Abstract: A power supply is plugged into an ordinary household electrical outlet and conditionally provides a high frequency current at a power receptacle operative to receive the power plug of an ordinary table lamp; which table lamp has a special fluorescent lamp screwed into its lamp socket. Provided the special fluorescent lamp is indeed screwed into the lamp socket, and provided the lamp'switch is in its ON position, the power supply does in fact supply high frequency current from its power receptacle; which high frequency current powers the special fluorescent lamp at a nominal power level, thereby to provide for high-efficacy luminous output. A storage battery contained within the power supply is kept fully charged by current derived from the power line voltage normally present at the electrical outlet and functions such as to cause high frequency current to be supplied from the output receptacle even if the power line voltage were to be disrupted.

Abstract: A current-fed parallel-resonant self-oscillating electronic ballast includes four special switching devices, each serving the function of a single switching transistor in a full-bridge inverter. Each special switching device includes two series-connected field effect transistors synchronously gated via positive feedback of a sinusoidal output voltage. The reason for using two series-connected field-effect transistors in lieu of a single field-effect transistor of higher voltage rating relates to the fact that, for the DC supply voltages associated with certain electronic ballast circuits powered from commonly encountered power line voltages, field-effect transistors of lower voltage ratings (e.g., 400 Volt) are substantially lower in cost per-unit Volt-Ampere rating as compared with field-effect transistors of higher voltage ratings (e.g., 800 Volt).

Abstract: A pre-converter is connected with AC power line voltage and provides DC voltage across a pair of DC terminals. A current-limiting inductor, a self-oscillating parallel-resonant inverter, and a periodically activated FET switch are series-connected with one another across the DC terminals. The inverter provides a high-frequency (e.g., 20-30 kHz) substantially sinusoidal output voltage across its output terminals. Each of plural rapid-start fluorescent lamps is connected across the output terminals by way of a current-limiting capacitor. The magnitude of the resulting lamp current depends on the RMS magnitude of the output voltage. In turn, for a given load condition, this RMS magnitude depends on the average magnitude of the unidirectional current drawn by the inverter from the DC terminals; which average magnitude is determined by the ON/OFF duty-cycle of the FET switch. The FET switch is turned ON/OFF at twice the frequency of the inverter's output voltage.

Abstract: A flashlight has a hybrid battery pack consisting of a primary-cell battery (ex: an Alkaline battery) and an auxiliary rechargeable battery of low internal resistance (ex: a Ni--Cad battery). Connected in circuit between the batteries and the flashlight's light bulb is a slide switch and an electronic control circuit. The slide switch has an OFF-position, an ON-position, and a spring-loaded variable BOOST-position. In full BOOST, the electronic control circuit operates such as to apply a voltage of about 1.5 times normal magnitude to the light bulb; thereby increasing the flashlight's light output by a factor of about 4.0 above normal. However, at that degree of BOOST, if indeed maintained on a continuous basis, the life of the light bulb will be shortened to about 15 minutes versus about 50 hours when used in the normal ON-position.

Abstract: A pre-converter is connected with AC power line voltage and provides DC rail voltage to a current-fed self-oscillating FET bridge inverter ballast. The inverter is loaded by way of a parallel-tuned L-C circuit connected across the bridge inverter's output, thereby providing a sinusoidal AC output voltage thereat. Each of several instant-start fluorescent lamps is connected via a current-limiting capacitor across the bridge inverter's output. The magnitude of the DC supply voltage is so chosen as to cause the magnitude of the AC output voltage to be such as to effectuate proper instant-starting of the fluorescent lamps. Each of the four FET's is driven by a sinusoidal AC voltage derived directly from a positive feedback winding on the tank-inductor of the L-C circuit. To enhance circuit efficiency, the absolute magnitude of the DC rail voltage is controlled to be just higher than the peak absolute magnitude of the AC power line voltage.

Abstract: An inverter-type electronic fluorescent lamp ballast normally powers a fluorescent lamp by way of a series-excited parallel-loaded resonant L-C circuit. During the lamp starting phase, as well as whenever the lamp is inoperative or not connected, inverter frequency is automatically increased substantially beyond resonance, thereby preventing circuit self-destruction which would otherwise probably result whenever an inverter is used for series-exciting an unloaded resonant L-C circuit.

Abstract: In an electronic ballast, an L-C series-resonant circuit is connected across the output of a full-bridge inverter while two Rapid-Start fluorescent lamps are series-connected across the tank capacitor of the L-C circuit. The full-bridge inverter is driven in such manner that the inverter's output voltage consists of a series of rectangular voltage pulses of alternating polarity and controllable width and frequency. When the lamps are fully powered, the inverter's output voltage consists of alternating pulses of frequency about equal to the natural resonance frequency of the L-C circuit and with each individual pulse-width about equal to half of the fundamental period of the natural resonance frequency of the L-C circuit.

Abstract: A plug-in timer has a set of input terminals and a set of output terminals as well as a contactor operable to make and/or break electrical connection between these sets of terminals in accordance with a pre-setable 24 hour program. The timer is powered from a small built-in battery, and comprises its own quartz clock and programming-and-control means. The contactor is actuated by a miniature DC motor through a gear and cam arrangement. The operation of the DC motor is controlled by the programming-and-control means, which provides power from the battery to the motor in accordance with a pre-set program; which pre-set program may be modified at any time by way of a keyboard and a numeric display means.The contactor operates by way of hard metal contacts and very little power dissipation occurs within the timer. The timer can be plugged into a special wall switch receptacle and then operates to programmably control the flow of power to the load controlled by this wall switch.

Abstract: A power-line-operated frequency-converting power supply provides a 30 kHz current-limited AC voltage at an output receptacle. A neon lamp is connected across the secondary winding of a gapped ferrite-type leakage transformer, the primary winding of which is connected with the output receptacle by way of a light-weight cord, thereby permitting the lamp-transformer combination to be located remotely from the power supply. The secondary winding is arranged to have a well defined inductance; which inductance is tuned to resonate at 30 Khz by way of a parallel-connected tuning capacitor. Tightly coupled with the secondary winding is a control winding with which is connected a protection circuit operative to place an auxiliary capacitor across the control winding in case the neon lamp fails to ignite within a few milli-seconds, thereby detuning the secondary winding enough to protect the power supply and the leakage transformer from sustained overload.

Abstract: A self-oscillating half-bridge inverter is powered from a power-line-operated rectifier means providing a DC supply voltage having a relatively high crest-factor. The inverter is loaded by way of a series-tuned high-Q LC circuit connected across this DC voltage. A pair of fluorescent lamps is series-connected across the tank-capacitor of the LC circuit. Also connected across the DC voltage is an arrangement of three energy-storing capacitors charged in series and discharged in parallel. The crest-factor of the current flowing through the fluorescent lamps is substantially lower than the crest-factor of the DC supply voltage.

Abstract: A power supply is integrally combined with a power plug, and the combination is adapted to be plugged into an ordinary household electrical outlet and operable to provide a power-line-isolated output of 120 Volt RMS at a frequency of about 30 kHz. The Volt-Ampere product available from this power supply is limited to be no more than 100 Volt-Ampere. Due to the high frequency, the electric shock hazard associated with this 120 Volt/30 kHz power supply is not higher than it is for a power supply having a voltage of only 30 Volt RMS at 60 Hz. The power supply, which also has receptacle means operable to receive and hold an ordinary electric power plug, is interposed between an ordinary household electrical outlet and the power plug of an ordinary table lamp.

Abstract: A half-bridge inverter is powered from an ordinary electric utility power line by way of a full wave rectifier-filter means. The high frequency voltage output of the inverter is loaded with a series-combination of a tank inductor and a tank capacitor, with a fluorescent lamp being connected in parallel with the tank capacitor. The ON-time of each of the inverter's two transistors is shorter than half the period of the high frequency voltage; thereby preventing the two transistors from conducting simultaneously; thereby, in turn, protecting the inverter from self-destruction in case of lamp failure.