| 摘要 |
PURPOSE:To reduce the cost of a telephone set by switching a reception amplifier to a receiver side at talking and switching a reception amplifier to a speaker side at loudspeaker call and closing both terminals of a handset, thereby simplifying the circuit without changing the DC resistance component of the telephone set independently of the talking and loudspeaker. CONSTITUTION:Since an on-hook switch 46 is set at loudspeaker, both terminals of the heandset 19 are short-circuited and the voice of the user is not inputted to a transmission amplifier 38. Since an on-hook switch 34 is thrown to the position of a terminal (a), the voice of the opposite side is outputted from the reception amplifier 30 to the speaker 12, and the voice of opposite party is intensified. Even when on-hook switches 34, 46 are switched depending on the talking and loudspeaker talking, since the DC resistance of the telephone set is always the sum of the DC resistances of the reception amplifier 30 and the transmission amplifier 38, the DC resistance of the telephone set at switching is unchanged and no dial mis-transmission is caused even with the said switching applied at dialing.
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