| 摘要 |
A headphone socket on an aircraft seat comprises a set of spring loaded terminals 5a, 6a that connect an electronic testing circuit to the headphone socket when an audio jack is not inserted. The testing circuit checks continuity of the audio signal to both left and right channels by amplifying 45, 46 and rectifying 55, 56 the signals before passing to an AND gate 60 which illuminates an LED 70 only if both left and right channels are present. When no headphone plug is inserted into the socket, the LED is illuminated if the terminals within the socket are properly connected to the audio signal. When the plug is inserted, the spring loaded contacts are moved and the testing circuit is disconnected to extinguish the LED. The visible indicator allows easy checking that each headphone socket on the plane is functioning, without plugging headphones into each socket separately. |
