Abstract: A power supply includes a battery source supplying power and a voltage converter circuit. The voltage converter circuit converts the power to the input voltage supplied to other circuitry. The voltage converter circuit varies the input voltage in response to a load current drawn by the other circuitry from the power supply.

Abstract: A method of conserving battery power includes providing an electrical conductor that is connectable between an audio source and an accessory of the audio source. The conductor is capable of conducting a first electrical signal, containing audio information from the audio source, to the accessory. A second electrical signal is applied to the conductor when the first electrical signal is not present on the conductor. An aspect of the second electrical signal is measured while it is being applied to the conductor. An amount of battery power supplied to the accessory is reduced when the measured aspect meets a predetermined condition.

Abstract: A device for charging a headphones battery. The device includes a first module adapted to receive a first power source through a first power source connector, the first module having a connector adapted to fit the headphones battery; and a second module adapted to receive a second power source through a second power source connector, the second power source connector distinct from the first power source connector, the second module having a connector adapted to fit the headphones battery, wherein the headphones battery is removed from the headphones and charged from the first power source when the first module is connected to the headphones battery and the headphones battery is removed from the headphones and charged from the second power source when the second module is connected to the headphones battery.

Abstract: A microphone has first and second differentially interconnected capsules angularly and linearly displaced from each other by a predetermined amount.