Abstract: A switching circuit for energizing a load, such as fluorescent lamp ballasts, in response to a control signal of preselected frequency superimposed on AC power circuits which supply the load. A triac is gated to conduct the AC power to the load by a circuit including an impedance element and a series resonant LC network tuned to the frequency of the control signal. The gate circuit is arranged to block the control signal during all but a small portion of each half cycle of the applied AC power, thereby reducing the consumption of control signal power. Further, a current limiting resistor is connected between the series resonant network and the triac to extend circuit life by protecting the triac from excess current without adversely affecting the signal-blocking function of the gate circuit.

Abstract: A wet-niche type lamp for providing underwater illumination in a swimming pool or the like includes an over-temperature protection circuit which interrupts the supply of electrical energy to the lamp when the level of the cooling water surrounding the lamp drops below a predetermined level. The circuit includes thermistor mounted in an heat exchange relationship with the surrounding water so that heat energy generated in the thermistor, as a consequence of the current flow through it, is normally transferred to the surrounding water. Should the level of the surrounding water drop below that of the thermistor, the thermistor heat energy quickly evaporates any remaining water film on the exterior surface of the thermistor to allow its temperature to rise. The control circuit, in response to the temperature increase, interrupts the flow of electrical energy to the lamp to prevent over-temperature operation.

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: An illumination control system for gas discharge lamps which can be dimmed is provided in which a central inverter produces a sinusoidal output voltage at about 23 kHz. The amplitude of the inverter output is adjustable to dim the lamps. A transmission line consisting of spaced wires having respective thick insulation sheaths distributes the high frequency power to remotely located assemblies of ballasts and lamps. The ballasts consist of passive linear components. A high power factor rectifier network is disclosed for providing a d-c input to the inverter from the 50/60 Hz mains. The inverter circuit is provided with novel controls for gradual start-up and turn-off and is protected against load fault currents and internal fault currents. Automatic and manual resets are provided for internal fault current and load fault current, respectively. The basic inverter circuit consists of two alternately conducting controllably conductive power switching devices.

Abstract: A dimmer circuit for providing gate signal to a gated semiconductor connected for at least partial bypass operation of a ballast element of an HID lamp, the gate signal being derived from a high frequency voltage in a predetermined range. The high frequency voltage is separated from other frequencies and converted to a voltage proportional to the frequency. The voltage is then converted to a pulse within the timed operational limits of the line voltage for gating the semiconductor, and hence producing a brightness of the lamp between predetermined limits of full dim to full bright. Preferably, the high frequency voltage carrying the control information arrives superimposed on the line voltage to thereby avoid having to use a separate set of leads to the lamp to provide light level control signalling.

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: A two-wire ballast arrangement is disclosed for fluorescent tubes having first and second terminals for supplying variable power to dim the fluorescent tube, a choke coil connected between the first terminal and the fluorescent tube and a filament transformer having a primary connected between the second terminal and a tap on the choke coil, the tap being selected to supply substantially constant voltage to the primary winding, the transformer having secondary windings to supply filament voltage to the fluorescent tube.

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: This invention relates to a circuit for lighting like a candlelight. The circuit has a lighting means having at least one incandescent lamp, and a control means which has a plurality of oscillators which can be oscillated with substantial equal frequencies. The control means controls an electric current flowing through the lighting means by a composite output of the oscillators. The each oscillator may be a relaxation oscillator which has a neon tube, and the control means may have a photo dependent resistor adapted to receive a composite light of lights emitted by the neon tubes, whereby the resistance of the photo dependent resistor being varied so as to control the electric current flowing through the lighting means.

Abstract: An apparatus that provides constant illumination in response to an AC input power source having variable magnitude. The input power passes through a full wave rectifier and is then switched by a solid state switching device having conductive and nonconductive states to a passive L-C filter. The output of the filter energizes one or more lamps to provide the illumination. A phase control circuit is responsive to a sync signal from the full wave rectifier and a feedback signal from the output of the filter and controls the phase angle conduction time of the solid state switching device at a repetition rate related to the frequency of the AC input power to provide constant illumination from the lamp.

Abstract: A circuit for providing remote control at a plurality of locations for a lighting system, such control functions including on/off, dimming intensity and rate of dimming. Visual indication of take control is also provided.

Abstract: Power consumption by traffic lights is reduced during the nighttime hours by allowing only part of each cycle of the alternating current to the lights to pass through. A photo conductive cell which is responsive to ambient light intensities controls a timing device which in turn controls the device for allowing current to flow to the lights. Detection devices monitor the proper operation of the devices which allow current to flow through the lights. In the event that an improper operation is detected, an override relay switches full power to the lights.

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: 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: A method of energizing a laser source stimulating flash lamp directly from an AC power line. Uncontrolled diodes couple the anode and cathode of the flash lamp directly to the AC line. The lamp is triggered by a separate triggering circuit which produces its trigger pulse at a predetermined phase of the AC power source. The use of high current carrying controlled rectifiers and large energy storage devices is thereby eliminated.

Abstract: The specification discloses a circuit which produces a gradual increase or decrease in the alternating current power applied to a series connected load. Double time constant gating circuitry and capacitor integration may be utilized in combination with self-heated thermistors to effect a gradual change in the conduction duration of a series connected control element.

Abstract: A control circuit for progressively and gradually varying the illumination intensity of incandescent lamps. The circuit comprises a source of alternating current connected in series with an electric lamp load which is also in series with a silicon controlled rectifier. This silicon control rectifier is rendered conductive when its gate is actuated by a gate signal generated by a programmable unijunction transistor (PUT). The conduction of the PUT depends on the voltage applied on its gate by a gate biasing circuit connected thereto and which comprises a charging capacitor. On the other hand, a charging circuit is connected across the silicon control rectifier whereas a second charging circuit is connected between the anode of the PUT and the first-mentioned charging circuit.

Abstract: This invention relates to circuitry for the connection of a load to and disconnection of a load from an AC power source. The circuitry is specifically useful in the on/off control of such as incandescent lamps, but not exclusively so, and provides for the timed disconnection of a load when the load is connected in series with the circuitry and AC power source, or alternately provides for the timed reduction of power delivered to the load.