Abstract: According to an example aspect of the present invention, there is provided an audio amplifier for use with a limited power source, the audio amplifier having: a power input terminal, a signal input terminal, a first DC to DC converter having an input connected to the power input terminal, an electrical energy storage device connected to an output of the first DC to DC converter, a second DC to DC converter having an input connected to the electrical energy storage device, an amplifier conductively connected to the output of the second DC to DC converter so as to be powered by the output of the second DC to DC converter, the amplifier also being conductively connected to the signal input terminal so as to receive a signal for amplification, and an output of the amplifier configured to be connected to a transducer such that the transducer may be driven by the amplifier.

Abstract: According to an example aspect of the present invention, there is provided an audio amplifier for use with a limited power source, the audio amplifier having: a power input terminal, a signal input terminal, a first DC to DC converter having an input connected to the power input terminal, an electrical energy storage device connected to an output of the first DC to DC converter, a second DC to DC converter having an input connected to the electrical energy storage device, an amplifier conductively connected to the output of the second DC to DC converter so as to be powered by the output of the second DC to DC converter, the amplifier also being conductively connected to the signal input terminal so as to receive a signal for amplification, and an output of the amplifier configured to be connected to a transducer such that the transducer may be driven by the amplifier.

Abstract: The invention relates to a method and apparatus for recognizing a digital audio signal in a system, in which at least some of the electronic components are at times in sleep or unenergized mode, in which method the digital audio signal is amplified and recognized, the amplified signal is decoded in a decoding circuit, the decoded signal is led to a signal processor for further processing and digital/analog conversion, and an audio signal is created from the analog signal. According to the invention, the amplified, undecoded signal is led directly to the signal- or microprocessor to be used and recognized, and the circuit implementing the decoder is kept in sleep mode unless a digital audio signal has been recognized.

Abstract: The invention relates to a method and apparatus for recognizing a digital audio signal in a system, in which at least some of the electronic components are at times in sleep or unenergized mode, in which method the digital audio signal is amplified and recognized, the amplified signal is decoded in a decoding circuit, the decoded signal is led to a signal processor for further processing and digital/analog conversion, and an audio signal is created from the analog signal. According to the invention, the amplified, undecoded signal is led directly to the signal- or microprocessor to be used and recognized, and the circuit implementing the decoder is kept in sleep mode unless a digital audio signal has been recognized.