Abstract: An electronic solid state system is provided for starting and operating one or more fluorescent lamps, and which supplies power to the lamps at a relatively high frequency, and at a relatively high power factor. The system includes a circuit which forces the line current to be proportional to the applied input voltage so as to maintain high power factor concomitantly with the removal of flicker by high frequency operation. High power efficiency is achieved through the use of a switching resonant inverter output circuit which is ideally suited to fluorescent lamp applications because of its low harmonic energy content, and because it can accommodate a wide range of resistive loads at high efficiency. The system may also incorporate a dimming circuit for the fluorescent lamps.

Abstract: A battery powered variable intensity hat mounted head lamp with a lamp shell mounting a lens and reflector assembly including an oscillator switching a power transistor mounted on the lamp shell for heat dissipation to control the lamp bulb, a printed circuit board in the lamp shell mounting the lamp bulb and the oscillator components, and a potentiometer mounted on the lamp shell for simultaneously varying both the on time and the off time in the duty cycle of the oscillator.

Abstract: A light indicating monitoring system includes a plurality of light emitting diodes (LED's) having a common ground connected to a phase controlled silicon controlled rectifier (SCR) circuit. The SCR circuit limits conduction of rectified AC energy through the LED's and through corresponding resistors connected in series with the LED's for limiting the current through the LED's. The SCR circuit thereby provides for operating low DC voltage LED's from a high AC voltage source with a minimum of power and heat generation in the current limiting resistors.

Abstract: A power circuit for a discharge lamp, in particular a flash lamp serving as light source in an optical analysis apparatus which comprises an electric power source outputting a d.c. voltage and capable of reabsorbing electrical energy, which also comprises an energy transferring circuit inserted between the electric power source and a first capacitor connected to the lamp, the capacitor being charged via the energy transferring circuit and adapted to store the energy required for each discharge across the lamp, the energy transferring circuit comprising a first current path comprising the primary winding of an autotransformer and adapted to transfer current from the electric power source to the first capacitor until the voltage across it reaches a predetermined value, and a second current path comprising a second capacitor for storing part of the surplus or non-used energy stored in the autotransformer during the charging of the first capacitor.

Abstract: Circuit for providing low ripple DC power supply from a single-phase AC source without the use of a filter capacitor. The circuit comprises a high leakage reactance transformer with a primary winding and two secondary windings arranged with the secondary windings on opposite sides of the primary winding, a leading current circuit connected to one secondary winding and a lagging current circuit connected to the other secondary winding, and a three-phase full wave rectifier bridge connected to the leading and lagging current circuits to provide a low ripple DC power output. The DC power supply circuit is used with a pulse generating circuit to provide pulsed operation of a gaseous discharge lamp such as a high pressure sodium vapor lamp, and produces desirable relationship of lamp watts to lamp volts for improved lamp life and uniformity of illumination.

Abstract: A dimmer circuit for an HID lamp is provided for supplying a square wave current therethrough at a constant frequency, but whose duty cycle is variable dependent on a sensed current level. The circuit employs a first pair of transistor switches for reversing polarity through the lamp at a low frequency rate. Associated with each of those transistors is a circuit having a transistor switch connected to a drive circuit employing a timer network. The timer network produces an output that is a square wave, the leading edge of which occurs at regular intervals at a high frequency rate. The trailing edge occurs dependent on a dim/bright voltage setting and upon the amount of current through a sensing resistor in series with the lamp.

Abstract: A lamp ballast connectable with a d.c. source comprises a regulating device having a voltage coil and a load coil. The voltage coil is connected in a circuit in parallel with the series-connected load coil and lamp. Alternate charge and discharge of a capacitor connected with the voltage coil impresses an alternating voltage thereacross. The capacitor is charged by current through the voltage coil and is discharged through a resonant commutating circuit comprising a thyristor triggered from an oscillator pulse circuit at a frequency of several KHz. The commutating circuit, which has a resonant frequency about twice that of the oscillator, further comprises a commutating reactor having substantially lower impedance than the load and voltage coils, a back current diode, and a resistance-capacitance dV/dt clamp that reduces back voltage spikes across the thyristor to safe rates of rise.

Abstract: The effect of a three way lamp bulb is achieved with a single filament bulb through the use of a variable duty cycle circuit and a touch control mounted in the base of the lamp. The circuit features a touch control incremented counter which controls the ramp rise rate of a sawtooth generator which is synchronized with the A. C. source. A trigger circuit accepts the sawtooth waveform to produce triac control pulses of time durations dependent upon the ramp rise rate.

Abstract: An oscillation generator providing a succession of oscillations repetitively and progressively varying in amplitude includes a feedback oscillator arranged to receive its operating voltage from a capacitor that is progressively charged from a periodically fluctuating voltage source by way of an SCR and a timing circuit arranged to progressively vary the timing during the fluctuation period of the source of firing signals applied to the SCR. The timing circuit includes a firing capacitor charged from a unidirectional source and semiconductor switches arranged, when the potential on the firing capacitor attains a predetermined level, to discharge the capacitor into the trigger electrode of the SCR. The time required for the potential on the firing capacitor to reach the predetermined level is varied by a saw-tooth generator that controls the charging potential for the capacitor.

Abstract: Variable inductance ballast apparatus for high-intensity discharge (HID) lamp comprises a laminated E-I core having non-magnetic gaps intermediate the E-conformed and I-conformed members. A main winding is carried on a leg of the E-conformed member to provide two closed magnetic paths. A control winding is wrapped about another of the legs and encircles only one of the closed magnetic paths. A bilateral switch connects to the control winding and is actuated by a signal-generating means which is responsive to a lamp operating condition to close the bilateral switch once each half cycle of energizing potential during normal lamp operation, with the resulting counter mmf decreasing the inductance of the ballast apparatus by a predetermined amount to control in a very accurate, simple and inexpensive fashion the average power delivered to the lamp.

Abstract: A supply and switching system for incandescent indicator lights is disclosed. A solid-state AC switch is used in conjunction with a current-limiting-transformer supply. The use of the current-limiting transformer protects the solid-state switch from the large current transients that are sometimes caused by failures in incandescent bulbs.

Abstract: Direct current ballasting and starting circuitry for efficiently operating a gaseous discharge lamp on direct current. A series-pass switching transistor in one of a pair of input lines alternately switches between on and off states to periodically supply pulses of energy from a source of direct current voltage. During steady-state operation, current sensing circuitry limits the maximum current conductable by the transistor such that the output of the circuitry is current regulated. A filter, in series with the transistor, smoothes the pulses of energy delivered by the transistor into direct current with a comparatively small alternating current component. Starting circuitry in series connection between the filter and an output terminal, senses the nonionized state of the lamp and provides a voltage pulse of sufficient magnitude and duration to initiate ionization in the lamp, but permits uninterfered passage of current through the filter to the output.

Abstract: An AND gate has a first input biased ON and a second input normally biased OFF. A switch selectively biases the second input ON. The output of the AND gate is fed back to the second input to bias the second input ON when the output is ON. A transistor connected in a common collector configuration has its base electrode connected to the output of the gate. A light-emitting diode is connected in the emitter circuit of the transistor.

Abstract: Apparatus for feeding a discharge lamp such as a mercury vapor lamp mounted in series with a choke from a direct current source comprising a chopper of direct current including an electronic switch and a detector of current intensity mounted in series with the choke. A first comparator compares the intensity of the current to a maximum level for opening the switch when the maximum level is reached and a second comparator compares the intensity of the current to a minimum value for closing the switch when the minimum value is reached. The lamp choke and current detector are connected in series with one another and a diode is mounted in parallel therewith and is oriented in the direction to pass current from the negative terminal towards the positive terminal of the direct current source.

Abstract: A low-pressure sodium vapor discharge lamp and a current stabilizing ballast element are connected in series to an energy source so that the lamp is operated by means of a non-sinusoidal current. The temperature of the wall of the discharge tube is maintained in an accurately defined interval and the instantaneous current density in the tube is kept below a first given value and the effective current density is kept above a second given value. This results in a relatively high luminous efficacy.

Abstract: The ballast circuit comprises a transistor having its collector and emitter and an emitter resistor in series with an alternating current operated current-controlled power supply and a gas discharge load device, such as a He-Ne gas laser. The transistor base is biased by a resistance voltage divider between the collector and the other end of the emitter resistor. A decoupling capacitor is connected between that end of the emitter resistor and the base.

Abstract: Pulse operating circuit for high intensity gaseous discharge lamps is provided with improved lamp starting device. The circuit comprises a direct current supply, a transistor switch in series with a ballast inductor and a lamp across the DC supply, an SCR switch connected across the inductor, a control circuit connected to the transistor switch for applying DC pulses to the lamp at a predetermined repetition rate and duty cycle, a sensing circuit for sensing the voltage across the inductor, and a variable SCR firing control circuit connected to the SCR and the first mentioned control circuit and responsive to the sensing circuit to control the firing of the SCR for limiting the peak current through the transistor switch during the lamp starting and warm-up interval.

Abstract: Energy is saved in lighting lamps by pulse operation at periodic duty cycles of less than 100% on time with little effect on apparent brightness when viewed by the normal human eye because of the quality of retention of a peak flask for a finite time. At periodic frequencies above about fourteen cycles the lamps appear to be continuously energized with little flicker.

Abstract: A circuit arrangement for triggering an arc discharge flash lamp that is directly coupled through series circuitry across an alternating current (AC) source. The lamp is ignited by a high voltage pulse generated from a pulse transformer in response to discharge of a voltage doubler charging capacitor by a controlled switch trigger from an RC timing circuit at a predetermined phase of the alternating current power source. Circuit operation is initiated by a switching arrangement which is coupled to the timing circuit through a zero crossing detector and shunt switch for assuring that the timing circuit starts at a predetermined point on the alternating current waveform. In this manner, the lamp reliably flashes with the same intensity each time a flash is requested.

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: 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: A circuit is disclosed which is suitable for controlling lighting in a building from a multiple number of points. AC current to light bulbs is controlled by a triac which in turn is controlled by the output of an optical coupler which is controlled by the output of a logic device. The output of said logic device is connected to control the input to the triac. Switches connecting to the input of the logic device each can independently determine energization or deenergization of the light bulbs.

Abstract: A self-triggering circuit for a gas-filled laser is disclosed. Electrical pulses which stimulate laser emission are applied to the laser cavity in response to an electrical energy change in the laser charging circuit when ionizing radiation is injected into the laser cavity. A semiconductor device of the type responsive to dv/dt, or of the type responsive to di/dt, is used as the self-triggering switch.

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 thyristor switch in series with the lamp, an RC timing circuit for periodically turning on the switch at predetermined intervals, and an LC circuit for turning the switch off. An inductor in series with a diode across the capacitor of the LC circuit provides for discharge of the capacitor to enable subsequent re-charging thereof, so as to provide the desired pulsed operation of the circuit. This mode of operation also provides for application of voltage to the lamp which is substantially higher than the supply voltage.

Abstract: Fire simulating apparatus includes a random number generator, a digital-to-analog converter for converting the output of the random number generator to an analog signal, a lamp coupled to a power source, a switching device coupled in series with the lamp and power source, and a control circuit for controlling the conductivity of the switching device in accordance with the magnitude of the analog signal.

Abstract: The disclosed spark source is adapted to generate electrical sparks to produce light for spectroscopic analysis of materials placed on the spark gap electrodes or introduced into the sparks. The disclosed spark source comprises a high voltage transformer having a secondary winding for supplying alternating current at a high voltage, a storage capacitor, a charging circuit including a rectifier connected between the secondary winding and the capacitor for charging the capacitor, spark gap electrodes having a spark gap therebetween, a discharge circuit including an electronic switching device connected between the capacitor and the spark gap electrodes for discharging the capacitor across the spark gap and control means for supplying a sequence of variably spaced triggering pulses to the input means of the electronic switching device for producing a sequence of spark cycles in which the capacitor is charged to substantially the same voltage for all of the spark cycles.

Abstract: Color properties of high pressure sodium vapor discharge lamps are improved by disclosed operating circuit for applying pulsed direct current to the lamp. The circuit comprises a direct current supply circuit, a transistor switch in series with a ballast inductor and a lamp across the supply circuit, an SCR switch connected across the inductor, a coasting diode across the inductor and lamp, and a control circuit connected to the switches for applying DC pulses to the lamp at a predetermined repetition rate and duty cycle. The circuit produces pulse waveforms which provide optimum color improvement in the lamp and makes efficient use of the energy supplied from the power source.

Abstract: Color properties of high pressure sodium vapor discharge lamps are improved by disclosed operating circuit for applying pulsed direct current to the lamp. The circuit comprises a direct current supply circuit, a transistor switch in series with the lamp and the primary of a transformer connected across the supply circuit, a diode in series with the secondary of the transformer connected across the supply circuit, and a control circuit connected to the transistor switch for applying DC pulses to the lamp at a predetermined repetition rate and duty cycle. The circuit produces pulse waveforms which provide substantial color improvement in the lamp and makes efficient use of the energy supplied from the power source.

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. The circuit includes a controlled thyristor switch in series with the lamp, an RC timing circuit for periodically turning on the switch at predetermined intervals, and an LC circuit for turning the switch off. An inductor comprising the primary winding of a transformer in series with a diode across the capacitor of the LC circuit provides for discharge of the capacitor to enable subsequent re-charging thereof, so as to produce the desired pulsed operation of the circuit, and the transformer secondary winding in series with a diode clamps the voltage of the primary winding. The disclosed arrangement prevents excessive voltage across the controlled switch and provides for the control of lamp wattage with respect to changes in lamp voltage.

Abstract: Color rendition of high pressure sodium vapor discharge lamps is improved by disclosed operating circuit for applying pulsed direct current to the lamp. The circuit includes a direct current ballast circuit having a low ripple factor, a filter capacitor charged by the output of the ballast circuit, and a pulsing circuit comprising a transistor switch which operates to apply DC pulses on the lamp at a predetermined repetition rate and duty cycle to provide desired color properties of the lamp.

Abstract: Increased color temperature of high pressure sodium vapor discharge lamps is provided by improved operating circuit for applying pulsed direct current to the lamp. The circuit includes a direct current ballast circuit having low ripple factor and a pulsing circuit comprising a controlled thyristor switch which operates to apply DC pulses to the lamp at a predetermined repetition rate and duty cycle. The described circuit provides for gradual increase in power applied to the discharge lamp during the starting interval and thereby avoids instability of lamp operation during that stage.

Abstract: A single phase, high frequency chopper ballast without large magnetic and capacitive components for gaseous discharge lamps such as the Lucalox.sup.R lamp is operated on full wave rectified line voltage. A small auxiliary capacitor stores energy during the peaks of the rectified line voltage when the voltage is high enough to maintain lamp discharge. During the low voltage valley regions the auxiliary capacitor is discharged to supply augmented chopper input voltage or load circuit voltage and provide energy to maintain lamp ionization during the valley regions until the rectified line voltage rises to a usable level.

Abstract: A system for controlling power applied to a gas discharge lamp by an AC source, wherein the power dissipated in the lamp during a half cycle is sensed by a measuring circuit. The measuring circuit provides output signals proportional to the current through and voltage across the lamp during its conduction. The measuring circuit output signals are multiplied and the difference between the resultant multiplier signal and a reference signal is time integrated and fed to a pulse width modulator. The pulse width modulator provides a pulse to a pulse transformer to trigger an SCR in series with the lamp at some point in the next half cycle, the point at which the SCR is triggered being determined by the power dissipated in the lamp in the previous half cycle. In another embodiment the SCR is replaced by a transistor and the pulse width modulator shuts off the transistor after the lamp has dissipated the desired amount of power in a given half cycle.

Abstract: The brightness of an LED display on an automobile instrument panel is independent of the battery voltage but does depend on the position of the instrument panel illumination dimmer potentiometer. The voltage applied to the LED is limited to a maximum by a zener diode control circuit and that voltage is reduced by a voltage detector circuit which senses the difference between the battery voltage and the dimmer potentiometer output voltage to reduce the LED voltage in proportion to that difference. The voltage detector circuit is disabled when vehicle parking lamps are turned off to insure maximum LED brightness in daytime driving.

Abstract: An electric incandescent lamp dimming combination fixture device having a subcombination which has at least one thyristor type of semiconductor component, with or without a voltage transient protecting "G.E. MOV." type VP varistor, as desired, and with or without a separate selective electric switch or switching means. The combination fixture device having, in at least one of its other embodiments, a subcombination of at least one-half-wave diode rectifier or rectifying means which is an semiconductor member, of the silicon type, with or without a varistor of the zink oxide doped with gallium oxide diode type, or even a diode of the germanium type, as desired, and at least one electrical selectively switching means.

Abstract: A power supply for an ac metal halide lamp employs a dc regulator in conjunction with a commutator for supplying the regulated dc power to the lamp with alternating polarity. A feedback circuit senses the dc voltage and current fed to the commutator and cooperates with the regulator to provide substantially constant power to the lamp. The commutator switching times are sufficiently rapid so that flickerless light output is obtained.

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.

Abstract: An electrical circuit for limiting surge currents through incandescent indicator or display lamps is disclosed. It is essentially a constant current device having a current controlling transistor in the load circuit to limit the initial surge current to a first value after, which the lamp itself limits the current. Provision is made for testing of the lamp and circuit by maintenance personnel.

Abstract: An electronic ballast circuit for reducing the warm up time of high intensity discharge (HID) lamps wherein lamp current flow is abruptly reduced by a switching means responsive to load voltage variations upon attainment of power in an amount sufficient to activate the HID lamp.