Abstract: Electronic earplugs, methods of enhancing and/or attenuating sound using electronic earplugs, and kits including electronic earplugs are provided. Certain electronic earplugs provided can deliver sound to a user's ear canal at levels below, equal to, and/or above ambient sound levels for specified ambient sound level ranges. Certain electronic earplugs provided can be switched between first and second settings with different sound level delivery settings. Certain electronic earplugs provided can be coupled with or integrated into two-way communication devices. Certain of such two-way communication devices can use induction to receive and transmit audio signals. Certain electronic earplugs provided can include a receive coil configured to allow remote radio signals to be received. Certain electronic earplugs provided can block at least about 35 dB of ambient sound when fully inserted into a user's ear canal.

Abstract: Inductively coupled battery charging systems and methods are provided. Transmit circuitry can include a transmit coil operatively part of a transmit resonant circuit exhibiting resonance at a transmit resonant frequency and an unloaded Q value of at least about 20. Transmit coil can generate a magnetic field at about the transmit resonant frequency. Rechargeable battery assembly can include a receive coil configured to receive inductively coupled current, and circuitry configured to rectify the current and communicate charging power to a storage cell. Receive coil can be part of a receive resonant circuit that exhibits resonance at about the transmit resonant frequency. Transmit circuitry can be configured to regulate alternating current produced in the transmit coil based on current flowing in the transmit resonant circuit and/or maintain the magnetic field at about the transmit resonant frequency by maintaining about a ninety degree phase shift between a square wave input and output.

Abstract: Inductively coupled battery charging systems and methods are provided. Transmit circuitry can include a transmit coil operatively part of a transmit resonant circuit that exhibits resonance at a transmit resonant frequency and an unloaded Q value of at least about 20. Transmit coil can generate a magnetic field at about the transmit resonant frequency. Rechargeable battery assembly can include a receive coil configured to receive inductively coupled current, and circuitry configured to rectify the current and communicate charging power to a storage cell. Receive coil can be part of a receive resonant circuit that exhibits resonance at about the transmit resonant frequency. Transmit circuitry can be configured to detect the rechargeable battery assembly by monitoring a load on the transmit coil.

Abstract: Inductively coupled battery charging systems and methods are provided. Transmit circuitry can include a transmit coil operatively part of a transmit resonant circuit that exhibits resonance at a transmit resonant frequency and an unloaded Q value of at least about 20. Transmit coil can generate a magnetic field at about the transmit resonant frequency. Rechargeable battery assembly can include a receive coil configured to receive inductively coupled current, and circuitry configured to rectify the current and communicate charging power to a storage cell. Receive coil can be part of a receive resonant circuit that exhibits resonance at about the transmit resonant frequency and an unloaded Q value of at least about 10. Transmit circuitry can include multiple transmit coils and can selectively discontinue production of alternating current in the coils generating fields that are not most strongly coupled to the receive coil.

Abstract: Systems and methods for maintaining a drive signal to a resonant circuit at a resonant frequency are provided. A system for maintaining a drive signal to a resonant circuit at a resonant frequency can include: an oscillator configured to provide an output to a phase comparator and a drive circuit, the drive circuit configured to provide a drive signal to a resonant circuit; a phase detector configured to receive a filtered version of the drive signal from the resonant circuit and provide a phase-indicating signal to the phase comparator; and the phase comparator, wherein the phase comparator is configured to provide a signal based on the phase difference between the oscillator output and the phase-indicating signal, wherein the signal from the phase comparator is used to control the frequency of the oscillator such that the phase difference converges to a fixed value.

Abstract: Electronic earplugs, methods of enhancing and/or attenuating sound using electronic earplugs, and kits including electronic earplugs are provided. Certain electronic earplugs provided can deliver sound to a user's ear canal at levels below, equal to, and/or above ambient sound levels for specified ambient sound level ranges. Certain electronic earplugs provided can be switched between first and second settings with different sound level delivery settings. Certain electronic earplugs provided can be coupled with or integrated into two-way communication devices. Certain of such two-way communication devices can use induction to receive and transmit audio signals. Certain electronic earplugs provided can include a receive coil configured to allow remote radio signals to be received. Certain electronic earplugs provided can block at least about 35 dB of ambient sound when fully inserted into a user's ear canal.