Abstract: A control circuit and ballasting means controls the light output of a gas discharge lamp in response to switches that are external to the ballast. The invention provides 3 levels of light output with single or multiple lamps. One embodiment of the invention can be mounted in a standard three-way socket for incandescent lamps. Another embodiment can be used to control multiple lamps in a ceiling-mounted fixture, replacing an inboard/outboard configured multiple ballast circuit. Other embodiments provide circuits that allow conventional dimming ballasts which are designed to be controlled with a low-voltage DC input signal to be controlled by a pair of switches connected to an AC power source.

Abstract: A capacitor arrangement across a direct current bus provides a high ripple current capability and high capacitance at a low cost. The circuit is used in electronic power conversion devices such as electric motor drives and inverters. A combination of film capacitors and electrolytic capacitors are used in the circuit and are placed across the dc bus. The film capacitors carry substantially all of the ripple current, while the electrolytic capacitors provide the majority of the capacitance. A resistor and a diode are used to isolate the electrolytic capacitors from the ripple current. This results in a low cost compact bus capacitor configuration.

Abstract: An electrostatic shielding system is provided for an AC motor to eliminate generation of destructive motor bearing currents. Conductive end turn shields are layered over the stator coil end turns at each end of the stator. Conductive grounding clips mechanically and electrically engage the end turn shields at one end of the clip, and electrically and mechanically engage the slotted openings in the stator at the other end. Conductive strips extend longitudinally along the stator slotted openings.

Abstract: A low cost power supply with enhanced safety protection for neon lamps connected in a midpoint commoned lamp configuration. The power supply has a return path which is isolated from the earth ground so that a fault current does not flow from the output terminals to the earth ground. The windings are phased in a series opposing configuration such that the voltages between the output terminals sum to zero. This power supply of mid-point connected secondary coil design is capable of operating lamp lengths that typically require 15,000 volts of open circuit voltage while not exceeding 7500 volts to ground when any one output terminal is grounded.

Abstract: A housing having a main section for holding an object, such as a ballast transformer, that has side walls and an open top. A lid having a shape conforming to that of the housing main section has side walls that fit over the main section side walls and covers the open top. The lid has an integral bracket of general U-shape that extends from one of the edges of the lid with the open part of the U facing upwardly toward the lid top. The bracket permits the housing and its contents to be suspended from an external mount.

Abstract: One half-connector terminates leads in the ballast, carrying electricity to and from the ballast coils. Another half-connector terminates leads outside the ballast, connected e. g. to carry power to lamp sockets. A hook extended from a first of the half-connectors engages a catch formed in a second. A retaining surface, preferably associated with the second half-connector, keeps the hook engaged with the catch. Preferably the space between the retaining surface and the catch is smaller than the unstressed dimension of the hook barb--but during the act of engagement the barb deforms to pass between the catch and surface; then the barb springs back into shape and is held behind the catch. In this process also preferably the retaining surface cooperates with the first half-connector to support the shaft or beam of the hook at both ends--as in a classical double-ended beam spring structure, contrasted with a cantilevered spring in a conventional hook and catch.

Abstract: A drive circuit for a switched reluctance motor has phase circuits connected to a common dump capacitor which receives residual magnetic energy from each phase coil when it is switched off. One or more recovering phase circuits are connected to the dump capacitor and comprise a controlled switch and diode whereby energy stored in the dump capacitor is returned to a recovering phase coil in sequence.

Abstract: A transformer enclosure design with a separate receptacle housing used for power transformers especially those used with neon lamps. The separate receptacle housing allows for multiple neon gas discharge tube mounting orientations and allows for multiple transformer mounting configurations with one enclosure design. The receptacle is used to connect the ends of a gas discharge lamp to the transformer. The receptacle housing contains a pair of recessed bushings and features a removable mounting bracket that can be mounted in several positions. Connection between the receptacle housing and the transformer housing is through flexible GTO wiring. The design allows an almost infinite number of spatial mounting orientations so that any tube orientation may be accommodated.

Abstract: A rectifier module assembly for a conventional three phase AC generator is formed into two crescent shaped rectifier modules so that the rectifier assembly can be mounted directly to the housing of the exciter rotor. The positive and negative rectifier modules are thermally conductive so that the exciter rotor itself can act as a heat sink for the rectifier module assembly. The rectifier module assembly occupies the space between and around the generator shaft and the exciter rotor windings.

Abstract: In accordance with the present invention, a hybrid sequence start circuit is provided for operating a plurality of instant start lamps. The circuit utilizes two coils, a primary and a secondary, and an electronic switch to start a plurality of series-connected, instant start lamps in sequence. When the circuit is energized, the electronic switch causes open circuit voltage to be applied to a first lamp by placing a low impedance across the other lamps, causing the first lamp to strike. The first lamp then conducts current, causing a starting capacitor in parallel with a second lamp to be charged, eventually, causing the second lamp to strike. The current through the second lamp shunts current away from the switch, and when this current drops below a predefined threshold level, the switch opens, effectively removing both the low impedance and the starting capacitor from the circuit.

Abstract: A two-winding, integrated-magnetic EMI filter provides damped common-mode and differential-mode inductances. The preferred embodiment of the filter has a magnetic core structure that incorporates a high-permeability C-core, a high-permeability I-core, and a low-permeability, lossy shunt. The three core pieces are assembled so as to form a structure that, similar to an E-I configuration, has two winding windows. The loss in the shunt aids in dissipating noise and it diminishes the effects of unwanted parasitic resonances by providing damping for the differential-mode inductance. Damping for the common-mode inductance is provided by losses in the C and I core pieces. Varying the reluctance of the shunt allows the differential-mode inductance to be adjusted separately from the common-mode inductance in order to tune the filter to remove desired noise frequencies. Another embodiment of the invention incorporates a high-permeability toroid core and a low-permeability, lossy shunt.

Abstract: In a power inverter, ripple current and bulk filtering are provided by a high-current, high-microfarad film capacitor arrangement; there is no separate snubber capacitor section. In an alternative embodiment, a small high-frequency film capacitor is connected in parallel with the bulk film capacitor arrangement, thereby increasing the operating range of the circuit.

Abstract: An improved connection assembly for connecting a centrifugal governor to the shaft of a fractional horsepower electric motor. The end of the rotor shaft to which the governor is mounted is provided with a circumferential ring seat and is flattened on diametrically opposed sides at the tip of the shaft. The governor assembly carrier plate is provided with a mounting sleeve that is shaped to mate with the flattened sides at the end of the rotor shaft. The mounting sleeve also has an opening that mates with the circumferential ring seat so that when the carrier plate is placed over the end of the rotor shaft, the carrier plate and the rotor shaft can be rotated 90 degrees relative to each other and the carrier plate will be captured by the ring seat to hold the governor assembly in place. A bowed retaining ring is also fitted within the ring seat and between the governor and the stator of the motor forcing the carrier plate of the governor assembly toward the end of the shaft.

Abstract: The present invention provides a sensorless circuit for detecting rotational speed of a rotor in an induction motor. The circuit includes a switch between the AC source driving the motor and a motor phase winding. When the switch is closed, there is developed across the phase winding a voltage waveform from the AC source. When the switch is subsequently opened, there is developed across the winding a residual voltage waveform induced by the rotor. The speed of the motor is determined by measuring a time interval between selected points on the voltage waveform.

Abstract: An electronic ballast includes a low cost circuit for power factor correction. A PWM circuit utilizes a wave form signal derived from the ballast inverter as a reference. The reference wave form signal is combined with a feed back signal to form a composite control signal that is compared with the reference voltage to create a pulse width modulated signal.

Abstract: A protection circuit for non-isolated ballasts that drive gas discharge lamps to prevent shock hazards. The device acts to prevent excessive leakage currents from flowing between the ballast and ground by introducing a higher common mode impedance path in the circuit. A two stage common mode filter assembly has a first common mode inductor series connected to a second common mode inductor. A first capacitor is connected across the common mode inductors. A second capacitor is connected between the junction of the first capacitor, the first inductor, the second inductor and ground. The circuit protects by reducing high frequency leakage currents.

Abstract: A method of assembling a leadless type ballast transformer having a connector at one end of the housing for accepting a mating connector which supplies voltage to the ballast and provides the operating voltage to the lamps controlled by the ballast. Uninsulated connection leads extending inwardly of the housing from the connector terminals to contact the lugs of a terminal board adjacent a transformer coil with the magnet wires of the transformer coils also being in contact with the terminal board lugs. The connection leads and magnet wires are permanently electrically connected to the terminal board lugs by ultrasonic welding.

Abstract: A preferred embodiment of the present invention provides a ballast circuit, comprising three sections: an input power section that receives a line AC signal as an input and provides a DC signal as an output; a pre-regulator section that conditions the DC signal; and a lamp driver section that drives a gas discharge lamp load. The pre-regulator section includes a transformer with an input winding, an output winding, and a current sense winding. The input winding receives the DC signal provided by the input power section. The output winding is connected in a flyback configuration with a flyback blocking diode, a bulk storage capacitor, and an output terminal for the conditioned DC signal. The current sense winding generates a signal proportional to the level of the transformer current. The transformer current is controlled by a flyback switch. A resonant capacitor is connected between the flyback switch input and ground, the resonant capacitor and the transformer forming a resonant circuit.

Abstract: The present invention provides a method and circuit for controlling the flow of current through a load. In a preferred embodiment, an oscillator generates a pulse signal of constant frequency. A pulse width modulator adjusts the duty cycle of the pulse signal in response to a dimming level signal input indicative of the desired level of current flow through the load. A converter receives the pulse signal as an input and converts it into an AC signal, the frequency of which follows the frequency of the pulse signal and the symmetry of which varies with the duty cycle of the pulse signal. The load is connected into a resonant circuit tuned such that a change in the symmetry of the AC signal changes the level of current flowing through the load.

Abstract: The present invention provides a low-cost power factor corrected electronic ballast circuit. A preferred embodiment includes a discontinuous conduction mode boost power factor correction circuit that is controlled with a simple pulse-width modulator (PWM) circuit comprising a few discrete components instead of an integrated circuit. The PWM circuit utilizes a reference waveform signal derived from the ballast inverter. The reference waveform is combined with a feedback signal to create a composite signal that is compared with a reference voltage to create a pulse-width-modulated signal. The feedback signal is used to regulate the bulk DC voltage. In an alternative embodiment, a feedforward signal that is proportional to the time-varying level of the rectified line voltage is added to the reference waveform and the feedback signal, and serves to modulate the pulse width of the boost circuit in a manner that reduces the harmonic distortion of the input current.