| 摘要 |
PROBLEM TO BE SOLVED: To use a portable telephone/simple portable telephone with both hands free as working or while driving an automobile by connecting a speaker with an output terminal of an amplifier and providing an input terminal of the amplifier with a plug from which a part for transmitting information is removed. SOLUTION: The plug 2 from which the part for transmitting information of an earphone microphone plug for portable telephone/simple portable telephone is removed is provided. The plug 2 is connected with the input terminal of the amplifier 1 and the speaker 3 is connected with the output terminal of the amplifier 1. When the plug 2 is inserted into a jack 8 of the portable telephone/simple portable telephone 10, a circuit to a built-in earphone is cut off, switched to an external earphone terminal, a receiving tone is transmitted from a built-in circuit to a part for receiving information of the plug 2 and further heard from the speaker 3 through the amplifier 1. On the other hand, transmission is originated from a built-in microphone through the built-in circuit by removing the part for transmitting information. Thus, the call is performed with hands free. In addition, conversation between plural persons is enabled.
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