Abstract: An AC switch (1) includes a first thyristor (T1), a second thyristor (T2), a third thyristor (T3), and a fourth thyristor (T4). The first thyristor (T1) has an anode connected to an AC power source (2), and a cathode connected to a load (3). The second thyristor (T2) is connected in antiparallel to the first thyristor (T1). The third thyristor (T3) has an anode connected to the AC power source (2), and a cathode connected to the load (3). The fourth thyristor (T4) is connected in antiparallel to the third thyristor (T3). A current detector (5) detects the AC current supplied from the AC power source (2) to the load (3). A controller (6) causes the first thyristor (T1) and the third thyristor (T3) to conduct alternately and causes the second thyristor (T2) and the fourth thyristor (T4) to conduct alternately, for each one-cycle period of the AC current, in accordance with the detection value from the current detector (5).

Abstract: A single-pole double-throw switch. In some embodiments, the switch includes a first switching transistor connected between a common terminal of the single-pole double-throw switch and a first switched terminal of the single-pole double-throw switch, a second switching transistor connected between the common terminal of the single-pole double-throw switch and a second switched terminal of the single-pole double-throw switch, a first auxiliary transistor connected between the common terminal of the single-pole double-throw switch and a gate of the first switching transistor, and a second auxiliary transistor connected between the common terminal of the single-pole double-throw switch and a gate of the second switching transistor.

Abstract: The present invention is directed to an electrical wiring device that includes a housing assembly having a plurality of terminals at least partially disposed therein, the plurality of terminals being configured to be coupled to an AC power source and at least one electrical load, the plurality of terminals being configured to provide the electrical wiring device with regulated AC power in a device energized state. At least one variable control mechanism is coupled to the housing assembly, the at least one variable control mechanism being configured to regulate power to the at least one electrical load by way of a control knob being user settable between a first adjustment stop and a second adjustment stop. A user accessible calibration button is included. At least one series pass element coupled to the at least one variable control mechanism, the at least one series pass element being configured to provide load power to the at least one electrical load in accordance with a user setting of the control knob.

Abstract: A ball forming device includes a first current control circuit to control discharge current arranged between a leading end of a wire and one electrode of a discharge continuing power source for causing discharge current to flow after dielectric breakdown, a second current control circuit to control shunting of discharge current arranged between a discharge electrode and the other electrode of the discharge continuing power source, and a fixed resistor connected to the second current control circuit in parallel as a shunt and controls current flowing through the second current control circuit, thereby a discharge voltage value is adequately changed.

Abstract: A system and method for discovering at least one dimming control protocol installed in a plurality of lighting devices and for controlling a plurality of dimming levels of the plurality of lighting devices are disclosed. The system may include at least one gateway that connects to at least one plurality of luminaires and/or LED's, at least one sensor subsystem and at least one power meter. The system and method may exchange information between a plurality of light devices and a self-organized, self-discovering gateway device. The gateway may use one or more known control protocols as an input and is able to handle multiple light devices that support different control protocols. This ability makes the gateway a universal lighting control gateway.

Abstract: A dimmer switch for an LED light source utilizes a thyristor-type device (“TTD”) having a first terminal, a second terminal, and a gate terminal. A low-voltage power supply converts alternating voltage into a direct voltage and is connected in parallel with the TTD. Gate current supplying circuitry is provided to supply current to the gate of the TTD, the gate current supplying circuitry powered by the low-voltage power supply and including a variable input device operable to vary a voltage waveform at the gate of the TTD in order to vary a voltage waveform provided at the second terminal.

Abstract: Disclosed are an LED lighting apparatus and a control circuit thereof which controls illumination of a lamp including LEDs using a dimmer. The LED lighting apparatus includes a flicker control unit which provides a control signal corresponding to a rectified voltage having a low angle corresponding to a preset low angle region and equal to or less than a preset level or detects an initial abnormal waveform diagram of the rectified voltage and provides a control signal corresponding to the abnormal waveform period, and controls a current path for light emission of the lamp.

Abstract: Disclosed is an alternator overvoltage protection circuit having a TRIAC and a MOSFET. The TRIAC is electrically connected to the MOSFET and the TRIAC is electrically connected to a magneto. The TRIAC is configured to ground the magneto when triggered by the MOSFET. The MOSFET is electrically connected to an alternator and configured to conduct when the alternator operates in an overvoltage condition. Also disclosed is a method of alternator overvoltage protection for a piece of outdoor power equipment, the method including providing a TRIAC and an alternator rotated by an engine having a magneto, wherein the alternator outputs a voltage when rotated by the engine. The method further includes configuring the TRIAC to ground the magneto when the alternator operates in an overvoltage condition, thereby disabling the magneto, which stops the rotation of the engine and stops the alternator from outputting voltage.

Abstract: A system of network-connected lighting devices also offers a distributed processing function that utilizes processor and/or memory resources if/when available in some or all of the lighting devices. In the examples, a resource manager receives a job for distributed processing using shared available resources. The resource manager identifies lighting devices having resources of the processors and/or the memories available for the distributed processing function. The resource manager distributes tasks and/or data of the received job through a communications network to identified lighting devices, for distributed processing. The resource manager also receives results of distributed processing for the received job, from the identified lighting devices through the communications network. The received results are processed to produce a composite result for a response to the received job.

Abstract: AC LED light engines powered directly from the AC power line contain circuitry of resistors, capacitors, diodes and transistors which enables a single string LEDs connected to series to efficiently produce light with a relatively low level of flicker as perceived by the human eye. The LEDs are driven by a current which is alternately capacitively-limited and resistively-limited. Capacitively-limited pulses of current are interposed between resistively-limited pulses of current so that the resulting output current ripple is at frequencies of 240 Hz or above which the human eye cannot perceive. The combination of resistively-limited current and capacitively-limited current results in a current drain from the power line which is generally sinusoidal and can have a power factor in excess of 0.70.

Abstract: A rapid cutoff device includes a thyristor AC switch for supplying an AC current from a first AC circuit to a second AC circuit. A serially-connected circuit of a first switch and a first capacitor parallel-connects with the first AC circuit. A serially-connected circuit of a second switch and a second capacitor parallel-connects with the second AC circuit. When cutting off the thyristor AC switch, the first switch is operated to conduct the first capacitor in a first direction for the AC current charging to the first capacitor, alternatively, the second switch is operated to conduct the second capacitor in a second direction for the AC current charging to the second capacitor, thereby lowering a current in the thyristor AC switch approaching a zero value and thus rapidly cutting off it.

Abstract: A lighting control system includes a master unit and a plurality of slave units. The slave units are respectively designed to consume power by operating lighting means, are supplied by a common power supply unit, can be provided with commands from the master unit, and are respectively provided with a control unit which modulates the power consumption of the associated slave unit according to a defined protocol. The master unit is designed to measure the power consumed by all slave units.

Abstract: A load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled to the gate of the thyristor, a control circuit, and an RF receiver for receiving an RF signal. The control circuit causes the gate coupling circuit to conduct a gate current to render the thyristor conductive at a firing time during a half cycle of the AC power source, and allows the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle. The thyristor is able to remain conductive independent of the magnitude of a load current conducted through the thyristor and to conduct the load current to and from the electrical load during a single half-cycle.

Abstract: A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.

Abstract: A detector circuit for actuating at least one fluorescent lamp may be configured such that the actuation of at least one fluorescent lamp occurs as a function of a first signal at a first input and as a function of a second signal at a second input if the first signal and the second signal are each greater than a first prescribed voltage and less than a second prescribed voltage during a start-up phase.

Abstract: A drive and control circuit for motor system and the method thereof are disclosed. The motor system could be applied in a cooling device, wherein the motor system comprises a rotor, a coil and a bridge circuit. The drive and control circuit comprises a control unit, a state detecting circuit, a load determining circuit, and a startup setting circuit. The startup setting circuit makes the motor run with the maximum torque, thus to make the motor system start up easily and quickly. The load determining circuit detects the load of the motor system, thus to generate a load determining signal to determine the speed of the motor system. The control unit could be realized with few components so as to save the costs.

Abstract: A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.

Abstract: A single-converter circuit-based LED driver circuit (10) with isolated multi-channel outputs is disclosed. The circuit (10) includes an IC control circuit (11), a plurality of isolated output channels (70, 74) each having an output current sensing and conditioning circuit (74, 90), and an output current regulation circuit (128). The output current regulation circuit (128) includes a voltage-sensing transformer winding (T4) that senses an output voltage level across a secondary side of the circuit (10), and a peak output current sensing component (156) that senses output currents from the isolated output channels and determines which channel has a highest current output. Additionally, the circuit (10) facilitates providing output current regulation when detected output voltage is below a predetermined threshold, and providing output current regulation when the detected output voltage is above the predetermined threshold.

Abstract: A phase-control dimming electronic ballast system and the control method thereof, wherein the system includes a phase controller, a converter, an inverter and a system controller. Moreover, the system controller senses a firing angle from the phase controller, and adjusts the output voltage of the converter and the switching frequency of the inverter to achieve the operation of dimming fluorescent lamp.

Abstract: A multilevel inverter using a cascade configuration with a device for equally controlling a power factor for each unit cell includes: a master controller, a plurality of power cells connected in series for each of three AC (Alternating Current) phases, a phase shift transformer for supplying a power cell input voltage, a CAN (Controller Area Network) communication network to provide a communication path between the master controller and each power cell, and cell controllers to control output voltages and output frequencies of the respective power cells according to a voltage command and a frequency command from the master controller, each cell controller having a pulse width modulator to generate a pulse width modulation control signal of a variable voltage and a variable frequency to the connected corresponding power cell, wherein each cell controller is configured to calculate a phase difference value of the corresponding power cell according to a preset total number of connected power cells and the floor n

Abstract: A method and apparatus for detecting a zero crossing or desired phase angle of a power line signal having a variable amplitude uses a ratio between a peak amplitude of the power line signal and the amplitude of the power line signal at a desired phase angle for a known amplitude version of the power line signal to detect when a variable amplitude version of the power line signal is at the desired phase angle or zero crossing. The detection of the phase angle is used to determine if a notch is present in the power line signal. A substantially constant width pulse is generated if a notch is detected regardless of the amplitude of the power line voltage or current. The invention is particularly useful in a lighting system for generating and detecting pulses used to communicate information from a power line communication controller to a series of electronic ballasts over a power line used to power the ballasts. The information can be used to control a dimming function of the ballasts.

Abstract: An apparatus for protecting an integrated circuit is applied to an electrical apparatus having a control unit. The control unit is used for controlling the integrated circuit and the protecting apparatus. The protecting apparatus includes a power input terminal, a power output terminal, and a control terminal. The power input terminal is used for receiving a power, and the power output terminal is used for outputting the power to the integrated circuit. The control terminal is used for receiving a control voltage of the control unit. When the control unit is at the power on mode, the control unit outputs the control voltage of a first level to prevent the power being input to the integrated circuit. Over a predetermined period of time, the control unit outputs the control voltage of a second level, so that the power can be input to the integrated through the protecting apparatus.

Abstract: An improved electron multiplier bias network that limits the response of the multiplier when the multiplier is faced with very large input signals, but then permits the multiplier to recover quickly following the large input signal.

Abstract: A dimming control system includes dimmer modules that receive dimming level information from one of at least two control modules. Each dimmer module includes a microprocessor that provides internal intelligence for controlling power to a load in response to dimming level information. Control modules receive industry standard protocol dimming information from various sources, convert it to dimming level information, and serially communicate the dimming level information to the dimmer modules. Dimmer modules and control modules are mounted in a rack which includes a backplane having a nonvolatile memory device that retains configuration data even if control modules are removed from the rack. An inactive control module can assume control of the rack when an active control module fails.

Abstract: An electrically powered flame simulator comprises at least two light sources, an integrated circuit electrically connected to the light sources for intermittently illuminating at least one of the light sources independently of other light sources such that the light sources together provide the effect of a flickering movement, and a power source for providing power to the integrated circuit. The flame simulator may be mounted in a decorative or ornamental device such as a candle or fire log, or used on decorative clothing, or may be part of a hazzard or warning system. One or more solid state light sources may also be used.

Abstract: A backlight used for a liquid crystal display includes a plurality of light emitting units, and a phase controller for adjusting the phase of the light emitting units. The light emitting units are turned on and off based on pulse signals of a predetermined cycle having an on-period and an off-period. Under the control of the phase controller, the light emitting units are turned on or off with different phases.

Abstract: Improvements to lighting systems, especially for entertainment and architectural applications are disclosed, including apparatus that permit a user to readily field-configure power distribution to branch circuits to be dimmed or un-dimmed, single- or multi-phase, as required; communication of data over existing power wiring by variations in output of dimmers; and improved methods for generating, managing, and distributing data specifying the physical and electrical configurations of a lighting system.

Abstract: Improvements to lighting systems, especially for entertainment and architectural applications are disclosed, including apparatus that permit a user to readily field-configure power distribution to branch circuits to be dimmed or un-dimmed, single- or multi-phase, as required; communication of data over existing power wiring by variations in output of dimmers; and improved methods for generating, managing, and distributing data specifying the physical and electrical configurations of a lighting system.

Abstract: A circuit for controlling the power to a load such as motor or incandescent lamp with reduced radio frequency interference employs a microcontroller to trigger a power transistor into a conductive state for supplying power to the load. The power transistor is switched on and off at a controlled slew rate through an integrator circuit coupled between the microcontroller and the power transistor. A zero current detector circuit detects when no current is passing through the load during each half cycle of the live voltage to switch the power transistor off by generating an interrupt request signal which is supplied to the microcontroller. After an operator selected time interval, the microcontroller generates a signal to switch the transistor to a conductive state.

Abstract: A high-efficiency self-regulated electronic ballast with a single characteristic curve for operating high-pressure sodium vapor lamps by means of an AC-to-DC converter circuit, a power factor correcting regulator circuit for reducing harmonic distortion, a high-frequency DC-to-AC converter circuit, a reducing autotransformer circuit with a current limiting inductor and an igniter, and a light-controlled switching circuit. The ballast is characterized in that it supplies a controlled high-frequency alternating voltage to the assembly of the limiting inductor and the lamp, whereby the ballast has a single characteristic curve, and in that the average power consumption of the lamp is determined on the basis of the single characteristic curve of the ballast within the standard regulation trapezoid defining the average consumption of the ballast/lamp assembly.

Abstract: A lamp power supply circuit for an image forming device, which is not provided with a full-wave rectifier and any additional noise reducing circuit but is capable of effectively suppressing inrush current not to produce noise that may cause erroneous operation of the image forming device and affect any external appliance. A lamp lighting control system for use in an image forming device, which can realize soft-starting of an exposure lamp or a fixing heater-lamp by gradually increasing a conducting angle .beta..sub.i (i=0, 1 . . . ) for applying a voltage to a lamp through phase control of an AC power-supply voltage V.sub.AC for an initial period of energizing the exposure lamp or the fixing heater-lamp. Wherein, the conducting angle is gradually increased per even-number unit of cycles of AC power-supply voltage V.sub.AC on the condition that even numbers of cycles in the same unit have the same conducting angle, e.g., .beta..sub.0 =.beta..sub.1 <.beta..sub.2 =.beta..sub.3 <.beta..sub.4 =.beta..sub.

Abstract: A lighting system made up of a plurality of light fixtures which each produce a light beam, in which each of a plurality of varying devices, each having an input and an output, and each capable of varying at least one parameter of the light beam from at least one of the light fixtures, is responsive to a first value received at the input, where the first value corresponds to the desired adjustment of a parameter of the light beam. Each of the varying devices is also capable of generating a second value which represents status information, and transmitting the second value via the output. A controller produces the first value and sends it to an output which is coupled to the input of the varying device. A monitoring device has an input and is separate from the controller, and its input is coupled to the output of the varying device.

Abstract: A dimming control for a high intensity lighting system uses a single additional control wire for control of the dimming function. The lighting system operates on multi-phase power. A transmitter for transmitting a control signal over the single control wire is connected between two of the phases of the multi-phase power supply, or between one phase and neutral. The transmitter, upon the occurrence of a predetermined condition, transmits a control signal to the single control wire. The control signal is a rectified portion of the power supply. The predetermined condition is motion as sensed by a motion sensor, operation of a timer, or operation of a manual switch. A receiver connected to the control line receives the control signal and switches the light to a low light output mode. The is accomplished by changing the capacitance of the ballast circuit for the light. Each lamp of the lighting system has a receiver connected to the single control wire.

Abstract: A dimming control system includes dimmer modules which receive dimming level information from a control module. Each dimmer modules includes a microprocessor which provides internal intelligence for controlling power to a load in response to the dimming level information. The control module receives industry standard protocol dimming information from various sources, converts it to dimming level information, and communicates the dimming level information to the dimmer modules through serial communication lines. The dimmer modules and control module are mounted in a rack which includes a backplane having nonvolatile memory device that retains configuration data even if the control module is removed from the rack. The dimmer modules implement a zero cross prediction method which includes detecting an actual zero cross, calculating an error, and adding the error to the period of a line power signal.

Abstract: An electronic stabilizer having a variable frequency soft start circuit, said circuit having a secondary coil coupled to a drive transformer of the electronic stabilizer. In the initial period when power is connected, the secondary coil may supply an induced voltage to a capacitor to generate a forward voltage to connect primary transistor to allow an inductance element to parallel the secondary coil to reduce the total inductance. The operating frequency of an LC oscillating circuit of the stabilizer hence increases. Relatively, the energy obtainable by the fluorescent lamp is reduced. The soft start circuit is further provided with a discharge loop of a secondary transistor for discharging of the capacitor to ensure that soft starts may be achieved under any conditions.

Abstract: Lamp dimmers are disclosed in which, in the course of varying average power supplied to the lamp load, the semiconductor power control devices transition between one and the other of substantially conductive and non-conductive power conditions, the duration of the transition by the power control devices themselves is increased beyond the minimum possible duration to reduce generated EMI. The dimmers disclosed provide for varying the direction, duration, shape, and phase angle of transitions.

Abstract: The present invention teaches a dimmer which incorporates an alternating current (AC) trigger which exhibits asymmetrical electrical characteristics. This eliminates the undesirable snap on hysteresis effect associated with conventional dimmers utilizing symmetrical AC triggers such as diacs and silicon bilateral switches (SBS). One embodiment of the present invention utilizes a zener diode to create the asymmetry. During one polarity of the AC source, the breakover voltage of the trigger is increased, forcing the trigger to breakover at a time later in the AC cycle than it would otherwise have with a symmetric trigger. This compensates for charge dumping of the phase control capacitor into the gate of the triac which would otherwise cause the snap on hysteresis effect.

Abstract: Apparatus for simulating a candle flame in which the current through the filament of a bulb is varied from a first value to a second value and back to the first value during spaced periods that vary from a period of maximum duration to a period of minimum duration that produces no observable flicker in an apparently random manner.

Abstract: An electronic delay turn off switch including a bridgelike array of four diodes disposed between an alternating current power source and a load wherein the diodes have anodes and cathodes in opposing disposition and having an SCR with anode connected to the interconnected cathodes and with cathode connected to the interconnected anodes. A gate isolation diode, a switch, a resistor-capacitor charge mode timer, and a DIAC are interconnected between the SCR anode and gate thereby providing an SCR turn on whenever the switch contacts are closed, and a delayed SCR turn off whenever the switch contacts are opened. In an alternate embodiment a variable resistor is added to enable user selection of the duration of turn off delay.

Abstract: A lighting control system distributes both the alternating current supply and control signals representing desired adjustments to fixture parameters, such as intensity, via connections including power contacts and, for control signals, an electrically isolating coupling comprising an effective source and detector.

Abstract: A dimming control circuit for a plurality of lighting fixtures includes a separate semiconductor power switch, e.g., a silicon-controlled rectifier or SCR, for providing controlled amounts of pulsed, unidirectional electrical current to each lighting fixture. In one embodiment, a pair of SCRs, arranged in parallel, opposed relationship, are controllably pulsed to produce an alternating sequence of positive and negative electrical current pulses, of independently-controlled duration, and oppositely-conducting diodes then connect these SCRs to two separate lighting fixture. One such lighting fixture thus receives the positive current pulses, and the other such lighting fixture thus receives the negative current pulses. In an alternative embodiment, each lighting fixture receives pulsed, unidirectional current directly from a separate, independently-controlled SCR.

Abstract: A lamp control module including a housing having a receptacle therein with a transformer winding wound around the inner walls of the receptacle in being operatively driven by a programmed microprocessor. The transformer winding of the module is further operative to be inductively coupled to a second transformer winding which is located within an on-off switch knob of a wall switch panel, and the second transformer winding is further connected to the gate electrode of an AC switch. Pulses which are generated in the lamp control module and controlled by data values stored in the microprocessor therein are transformer coupled from the housing receptacle transformer winding into the knob switch transformer and then to the gate electrode of the AC switch. These pulses are operative to control the phase angle and conduction time of the Triac and in turn control the conduction time that an AC voltage is applied from an external AC voltage source to a lamp.

Abstract: A dimmer with reduced filtering losses is connected into a conductor supplying power to a load from a mains power supply. It conventionally comprises a triac in series with a filter inductor between an input terminal and an output terminal and a circuit generating triggering signals for the triac. To reduce the losses in the inductor, which conventionally is in series with the load at all times but is active only during moments following triggering of the triac, to reduce the amplitude of the transient currents, a second triac triggered by a circuit with a time-delay greater than the time constant defined by the filter capacitor and inductor diverts the load current. An auxiliary low-value inductor attenuates transients due to triggering of the second triac.

Abstract: A dimming system provides power from a switch-controlled power source in series with a leakage auto-transformer to a compact fluorescent lamp. The system incorporates a high-frequency resonant converter that provides high voltages to strike and maintain an electric discharge in the lamp. The converter is loaded in parallel by the lamp, whose impedance damps the converter to stabilize lamp operation. An inductor, connected between the leakage auto-transformer and the resonant converter, isolates the switch-controlled power source from the high-frequency voltage. The system can be used with a variety of standard leakage reactance auto-transformers to provide full-range dimming of compact fluorescent lamps from 5 to 100 percent light output with minimal flicker.

Abstract: A circuit arrangement for generating a pulsatory supply voltage for a load (1), such as a halogen incandescent lamp, from a source of direct voltage, in which a predetermined effective value of the supply voltage remains substantially constant in the case of a varying direct voltage. A switch (2) supplies the supply voltage from which a low-pass filter generates a mean value voltage. The mean value voltage is applied to a Schmitt trigger circuit (3) which controls the switch whose first switching threshold is constant and is derived from a reference voltage which is present at a first input of the Schmitt trigger circuit. A second switching threshold of the switch varies oppositely with respect to a decreasing direct voltage.

Abstract: A circuit and a method for controlling the dimming of incandescent lights using a pair of antiparallel connected SCRs which are fired at the same frequency as the frequency of the AC line power to achieve phase control of the power supplied to the light. Only one SCR of the pair is utilized in the 0% to 50% brightness range while both SCRs are utilized in the 51% to 100% brightness range.

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: A voltage reduction unit for reducing the voltage supplied to a lighting element to a prescribed value and for maintaining the prescribed voltage across the lighting element independently of the current flowing through it. A lighting element is connected in series with a current switch, and the current switch is controlled by a voltage/current control unit which monitors the lighting element for changes and voltage and current characteristics. The voltage/current control unit comprises a differentiator circuit for detecting a slope of an AC voltage waveform and a comparator circuit for detecting a prescribed voltage on the waveform. The voltage/current control unit allows current to flow through the lighting element when both a first prescribed voltage and a prescribed voltage slope of the voltage waveform is detected, and it inhibits current flow through the lighting element when a second prescribed voltage is detected.

Abstract: This invention is a circuit for controlling the power received by a load. The operation of this circuit is based on variations of voltage amplitude rather than phase as is the case with other circuits utilizing the phase control principle. A pair of terminals couple an AC service voltage source to a load and to a distributor switch by which an operator can arrange for the load to receive power directly from the AC service voltage source, or through a transformer and a gated switch, or through a diode. The operation, by way of the transformer and the gated switch or by way of the diode, provides not only "soft-start" and protection from power line transients (voltage spikes) to the load but also prevents it from emitting acoustical noise.

Abstract: Apparatus for simulating a candle flame in which the current through the filament of a bulb is varied from a first value to a second value and back to the first value during spaced periods that vary from a period of maximum duration to a period of minimum duration that produces no observable flicker in an apparently random manner.