Abstract: A starting and operating circuit for a discharge lamp in which the ballast reactance includes first, second and third coil segments with the third coil segment compromising part of the ignitor circuit and being electrically connected between the first and second coil segments.

Abstract: A protective system to prevent a dry metallized film capacitor from rupturing its case or catching fire in the event that an internal short or fault occurs within the capacitor section utilizes a fuse and a thermal protector connected in series with the capacitor section and within its case. The fuse serves to protect the unit from a fault-induced low resistance high current in-rush, while the thermal protector is triggered by a fault-induced high resistance low current. A heat reflective circumferential sheet and the positioning of thermal protector maximize its value in the protective system.

Abstract: A thermal protection device for a dual input voltage lighting fixture apparatus which includes a reversible connector for coupling either of two possible input voltages to the appropriate terminal of a winding of a transformer/ballast apparatus via a normally closed contact of a heat responsive thermal switch having a heating element electrically coupled to the reversible connector and thermally coupled to the closed contact. The latter contact opens in response to a level of heat above a given value. The transformer winding has two connection terminals, one of which is a tap point, connected to the reversible connector. The connection scheme provides the same energizing voltage to the heating element for each of the two different possible levels of the input voltage. The apparatus will automatically indicate if the connector is reverse connected for either of the two input voltages.

Abstract: Apparatus for sequentially igniting and serially operating a pair of electric discharge lamps from a source of AC supply voltage. The apparatus includes a transformer with a primary winding and first and second secondary windings mounted on a magnetic core having a slot under the second secondary winding. The first secondary winding has a high leakage reactance and the windings are serially connected with the secondary windings wound in opposition to one another. First and second capacitors are connected in series with the first and second lamps, respectively, to prevent the flow of DC current therethrough. By a novel choice of the ratios of the capacitance values of the second capacitor to the first capacitor and of the slot dimensions, superior operating characteristics for the apparatus are achieved.

Abstract: A power supplier for providing a regulated high-frequency AC output with a bucking and boosting section and a push-pull output section in which a common switching element is used in both the bucking and boosting section and in the push-pull output section.

Abstract: A protective system to prevent a dry metallized film capacitor from exploding or catching fire in the event that an internal short or fault occurs within the capacitor section utilizes a fuse and a thermal protector connected in series with the capacitor section and within its case. The fuse serves to protect the unit from a fault-induced low resistance high current in-rush, while the thermal protector is triggered by a fault-induced high resistance low current. A heat reflective circumferential sheet and positioning of thermal protector maximize its value in the protective system.

Abstract: Apparatus for igniting and operating a high pressure arc discharge lamp includes a pulse generating circuit for generating high voltage pulses for starting the lamp. The pulse generating circuit is comprised of a step-up transformer, a start capacitor, a voltage sensitive bidirectional switch (e.g., a sidac) and an impedance which forms a charge circuit for the capacitor. The capacitor discharges via the switch and a part of the transformer to generate a high voltage pulse which is coupled to the lamp electrodes. An auxiliary capacitor and a serially connected inductor are coupled in parallel with the pulse generating circuit so as to clamp the open circuit voltage at a high level upon generation of the ignition pulse thereby to maintain a level of lamp current sufficient to sustain the discharge arc. This makes the lamp ignition more reliable and extends the lamp life.

Abstract: A ballast-inverter circuit for a discharge lamp with preheatable electrodes. The lamp is connected to the supply voltage input terminals via a ballast impedance. A triac provides a preheat current path for the lamp electrodes and has a gate electrode connected to an RC timing circuit. A PTC resistor is coupled between one input terminal and the timing circuit to trigger the triac so as to heat up the lamp electrodes and assist the lamp to ignite. The PTC resistor heats up until its resistance is so high that the timing circuit is no longer able to trigger the triac into conduction. The electrode preheat circuit is effectively disconnected from the lamp electrodes when the lamp is in operation.

Abstract: A discharge lamp ballast circuit comprises at least one discharge lamp connected in series circuit with a ballast capacitor and inductor across a pair of input terminals for a source of A.C. supply voltage. A controlled semiconductor switching element is coupled across the lamp electrodes and a control circuit for the switching element is coupled to the input terminals and to a control electrode of the switching element. A voltage dependent non-linear impedance device is connected in shunt with the capacitor so as to limit the capacitor voltage to a predetermined value. The voltage dependent impedance device prevents the occurrence of hazardous voltage levels in the circuit and improves the stability during the warm up phase.

Abstract: Microwave oven with a self-regulating circuit operated from a low voltage a.c. source based upon a substantially constant current transformer and condenser series combination and having a return path for current on alternate half cycles. For defrosting food the magnetron is operated at partial power which is achieved by decreasing the voltage applied to the magnetron. This is done either by increasing the capacitive reactance in series with the secondary of the transformer or by decreasing the secondary voltage. Switching problems are solved by providing the arrangement of the invention at the grounded end of the transformer secondary. The self-regulating circuit is required to be of the type which has one end of the secondary winding grounded.

Abstract: A circuit for protecting a ballast in a high pressure metal vapor, such as sodium, lamp system which includes means for interrupting the power supply to the ballast in the event that no current is flowing through the lamp, once the system has been energized. The circuit has automatic compensation for short interruptions and for the time which it normally requires for the lamp to ignite. The absence of current flow through the lamp is sensed and this information used to provide the protection.

Abstract: A magnetron energizing circuit preferably uses two transformers of the high leakage reactance type having isolated secondaries with an end terminal of each secondary connected to a common point which is at ground potential. The secondaries are connected to series condensers in two loops which provide leading current flowing in the secondaries at all times while both are connected in the circuit to produce saturation in the respective cores of the secondaries whereby to achieve substantially constant current and good regulation for variations in the primary voltage. A single magnetron is served by the circuit and variations in the loading of the magnetron are also compensated for by virtue of the substantially constant current circuit. The secondaries are connected in opposite phase with respect to the respective capacitors which they serve to charge to obtain a full wave doubler operation when the transformers are both in circuit but with low peak current.

Abstract: A capacitor winding machine includes a first core loading and winding position for winding a predetermined number of turns of two metallized films onto the core prior to moving the winding to a second finishing and ejecting position. Once the predetermined number of windings have been applied to the core in the first position, the winding is moved with the films under tension between the core and their respective supply rolls to the second position and the films are attached to and terminated from a second core which has then been loaded into the first loading position. The first core is then rotated to wind the free ends of the film onto the core which may then be heat or otherwise sealed to complete the metallized plastic film capacitor prior to being ejected from the machine.