| 摘要 |
An adapter making it possible for the pilot of an aircraft equipped with a navigation-communication system whose audio output is permanently connected to a loudspeaker to hear well with ordinary earphones without interfering with the concurrent operation of the loudspeaker. The adapter is constituted by a battery-operated Darlington amplifier whose high-impedance input is connected across the relatively low impedance audio output of the system whereby virtually no load is imposed thereon. The low-impedance output of the amplifier is connected to the earphones in series with a volume control resistor whereby a reduction in volume results in a diminished current drain, thereby prolonging battery life. A redundant power supply is provided constituted by two cells and a switch adapted to connect either of the cells individually or both cells in series to the amplifier so that even after both cells are close to exhaustion, they are still capable of powering the amplifier.
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