Abstract: An ultrasonic transmitter. The ultrasonic transmitter includes a first enclosure, a second enclosure, a piezoelectric transducer, a first piston, and a second piston. The first enclosure has an opening for directing an output of the ultrasonic transmitter in a first direction and a wall opposite the opening. The second enclosure has a first opening aligned in the first direction and a second opening opposite the first opening. The second enclosure is positioned in the first enclosure with the second opening directed toward the wall. The piezoelectric transducer is positioned in the second enclosure and movable relative to the first enclosure. When an ultrasonic electric signal is applied to the piezoelectric transducer, the piezoelectric transducer expands and contracts pulsing the first and second pistons to produce ultrasonic sound waves from the first and second openings which combine and our output by the ultrasonic transmitter.

Abstract: A charging apparatus (102), system (100) and method (500) are provided for charging and/or powering a wearable electronic device, such as electronic eyeglasses. The charging apparatus comprises an acoustic horn, a piezoelectric transducer, and charger circuitry for converting ultrasonic waves received at the horn into a charging signal. The charging signal is used for charging and/or powering the wearable electronic device while the device is being worn.

Abstract: Disclosed herein are methods and systems for providing a ballast load for a magnetic resonance power source. One embodiment takes the form of a magnetic resonance power source that includes a source coil, a load-detection module, a tunable ballast coil circuit, and a controller programmed to carry out a set of functions. The set of functions includes obtaining, via the load-detection module, an estimated load on the source coil. The set of functions also includes decreasing the power received by the tunable ballast coil circuit from the source coil when the estimated load on the source coil is greater than a desired load on the source coil. The set of functions also includes increasing the power received by the tunable ballast coil circuit from the source coil when the estimated load on the source coil is less than the desired load on the source coil.

Abstract: An ultrasonic transmitter. The ultrasonic transmitter includes a first enclosure, a second enclosure, a piezoelectric transducer, a first piston, and a second piston. The first enclosure has an opening for directing an output of the ultrasonic transmitter in a first direction and a wall opposite the opening. The second enclosure has a first opening aligned in the first direction and a second opening opposite the first opening. The second enclosure is positioned in the first enclosure with the second opening directed toward the wall. The piezoelectric transducer is positioned in the second enclosure and movable relative to the first enclosure. When an ultrasonic electric signal is applied to the piezoelectric transducer, the piezoelectric transducer expands and contracts pulsing the first and second pistons to produce ultrasonic sound waves from the first and second openings which combine and our output by the ultrasonic transmitter.

Abstract: A charging apparatus (102), system (100) and method (500) are provided for charging and/or powering a wearable electronic device, such as electronic eyeglasses. The charging apparatus comprises an acoustic horn, a piezoelectric transducer, and charger circuitry for converting ultrasonic waves received at the horn into a charging signal. The charging signal is used for charging and/or powering the wearable electronic device while the device is being worn.

Abstract: Disclosed herein are methods and systems for providing a ballast load for a magnetic resonance power source. One embodiment takes the form of a magnetic resonance power source that includes a source coil, a load-detection module, a tunable ballast coil circuit, and a controller programmed to carry out a set of functions. The set of functions includes obtaining, via the load-detection module, an estimated load on the source coil. The set of functions also includes decreasing the power received by the tunable ballast coil circuit from the source coil when the estimated load on the source coil is greater than a desired load on the source coil. The set of functions also includes increasing the power received by the tunable ballast coil circuit from the source coil when the estimated load on the source coil is less than the desired load on the source coil.

Abstract: A power converter having reduced switching transients includes a conversion inductance, a pulse width modulation (PWM) controller, a conversion inductance, and a switch transistor. A low pass filter is connected between the PWM controller and the switch transistor to filter a PWM signal produced by the PWM controller and produce a filtered PWM signal. The switching transistor switches current through the conversion inductance responsive to the filtered PWM signal. The low pass filter filters out harmonic content of the PWM signal that is above the fundamental frequency in a way that maintains most of the harmonic content of the PWM signal to substantially eliminate higher harmonic elements which are conventionally responsible for transients across the conversion inductance.

Abstract: A power converter having reduced switching transients includes a conversion inductance, a pulse width modulation (PWM) controller, a conversion inductance, and a switch transistor. A low pass filter is connected between the PWM controller and the switch transistor to filter a PWM signal produced by the PWM controller and produce a filtered PWM signal. The switching transistor switches current through the conversion inductance responsive to the filtered PWM signal. The low pass filter filters out harmonic content of the PWM signal that is above the fundamental frequency in a way that maintains most of the harmonic content of the PWM signal to substantially eliminate higher harmonic elements which are conventionally responsible for transients across the conversion inductance.

Abstract: An isolation apparatus and method are provided for bi-directional communication over a single wire link without circuit latch up. The isolation is provided by two identical but independent switching circuits designed to eliminate latch up while controlling two optical isolators in a bi-directional mode of operation.

Abstract: An isolation apparatus and method are provided for bi-directional communication over a single wire link without circuit latch up. The isolation is provided by two identical but independent switching circuits designed to eliminate latch up while controlling two optical isolators in a bi-directional mode of operation.

Abstract: A broadband communications system for providing radio frequency (RF) signals to subscriber equipment that includes an amplifier for amplifying the RF signals and for providing an indication of the presence of the RF signals. The amplifier includes an input for receiving the RF signals, a first gain circuit for amplifying the RF signals and providing amplified RF signals, and an output for providing the amplified RF signals to the subscriber equipment.

Abstract: A normally straight-through connection from a computer fax modem to a fax machine, or other fax sender to fax receiver, is briefly interrupted under battery power to supply the fax modem with a simulated dialtone and the fax machine with a simulated ring signal, which is supplied via a DC-to-DC converter activated by the same clock signal from which the dialtone and simulated ring signal are derived.

Abstract: A monostable circuit with device-status feedback control to an external timing terminal is used to controllably change the magnetization state of a ferrite phase shifter core. A pair of such bistable circuits with suitable feedback controls permits a single command pulse of controlled duration to controllably both reset a ferrite core to a saturated magnetic state and then subsequently set the core to a desired non-saturated magnetization state (corresponding to the time duration of the single command pulse). By addition of suitable steering circuits, the controlled resetting and setting of one or more pairs of such ferrite cores can also be achieved using the same single command pulse. The ability to both reset and set plural ferrite phase shifter cores with but a single command pulse of controlled duration permits considerable simplification of beam steering control wiring for a two-dimensional phased array of RF radiators (e.g., so as to provide electronic beam steering control).

Abstract: Apparatus for extracting the fundamental frequency from a complex audio wave form and for producing a pulse representation of said fundamental frequency includes a low pass filter having a frequency response characteristic which tends to exclude harmonics together with a control circuit including amplifier means, peak detector means and voltage to current converter means for supplying a control signal to the low pass filter thereby to vary the cutoff frequency of the filter and to maintain substantially constant amplitude of the fundmental wave form together with voltage comparator means for comparing the peaks of an alternating current quantity dependent upon the output of said filter with a direct current quantity proportional to the output of the filter, said comparator means thereby producing a pulse per cycle of said fundamental frequency.