| 摘要 |
In an electronic stethoscope which includes a pickup head, a microphone, a tubular accoustic connection between the pickup head and microphone, an amplifier receiving an input from the microphone, a speaker coupled to the output of the amplifier, a binaural headpiece and tubes acoustically coupling the output of the speaker to the binaural headpiece, there is included a switch by means of which a momentary on operation can be achieved and a timer responsive to the switch to couple power to amplifier circuit, the timer adapted to shut power off after a predetermined period of time. Preferably the amplifier is an integrated circuit operational amplifier with a filter circuit which brings up lower frequencies interposed between the amplifier and speaker.
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