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: A saturable reactor for correction of pincushion distortion of a TV picture tube raster has, in one form, a magnetically saturable two window core. A single wire control coil is wound transversely around the central leg segment of the core and is connected with the vertical frequency sawtooth driver in a parabolic wave shaping network. A first load coil, wound transversely around one outer core leg, is connected in series circuit with the horizontal frequency sawtooth driver and the horizontal deflection coils. A second load coil is wound around the exterior of the core, in lengthwise embracing relation to its other outer leg, and is connected in series with the vertical deflection coils and also in a phase inverting resonant loop circuit.

Abstract: A temperature sensor for a food freezer alarm or the like comprises a sensing element such as a thermistor enclosed in a capsule filled with a material (e.g., water-alcohol mixture) that melts and freezes at a predetermined temperature (e.g., 25.degree. F.), with such change of state occurring as a result of change of latent heat content of the material.

Abstract: An electroacoustical transducer element comprises a piezoelectric disc flatwise bonded to a metal diaphragm, the bond being at the plane of neutral stress. The transducer element defines the front wall of a sealed chamber that serves as an infinite baffle. In front of the element is a resonant acoustical cavity that matches impedance of the element to that of the ambient medium and comprises concentric axially short large and small diameter cylindrical chamber portions, the small diameter portion providing a front outlet from the large diameter one.

Abstract: A saturable reactor for correction of pincushion distortion of a TV picture tube raster has, in one form, a magnetically saturable two window core. A single wire control coil is wound transversely around the central leg segment of the core and is connected with the vertical frequency sawtooth driver in a parabolic wave shaping network. A first load coil, wound transversely around one outer core leg, is connected in series circuit with the horizontal frequency sawtooth driver and the horizontal deflection coils. A second load coil is wound around the exterior of the core, in lengthwise embracing relation to its other outer leg, and is connected in series with the vertical deflection coils and also in a phase inverting resonant loop circuit.