Importance

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Abstract

An object of the invention is to provide a voice input/output automatic switching circuit used in a hand-held microphone with speaker of a communication device such as a transceiver. In the voice input/output automatic switching circuit, a circuit for detecting a handsfree speaker/microphone can be simply configured without requiring a particular detection terminal and moreover, a sufficient countermeasure can be taken against a malfunction caused upon its switching. The voice input/output automatic switching circuit includes a voice input automatic switching circuit constituted of: a current detecting resistor 5 having a low resistance value, arranged on an output line of a microphone 1; a comparator 4 which detects a voltage drop across the current detecting resistor 5 and switches the output; an analog switch 3 which automatically switches, according to the state of an output signal of the comparator 4, an electrical signal circuit on the side of a microphone 2 of the hand-held microphone B with speaker to the side of the microphone 1 of the handsfree speaker/microphone C; and a capacitor 6 having a sufficiently low impedance with respect to a voice component, connected in parallel to the current detecting resistor 5.

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First Claim