| 摘要 |
PURPOSE: An outside broadcasting transmitting apparatus using a subscriber's extension line of a key phone system is provided to control a relay for power supply of the outside broadcasting transmitting apparatus according to the voltage of polarity supplied from the subscriber's line of the key phone system, thereby increasing the space in design of the key phone system. CONSTITUTION: The apparatus(1) is connected between extension line of a key phone system(2) and an outside broadcasting system(3). A DC(Direct Current) holding circuit unit(4) is connected to an extension line of the key phone system(2) and occupies a line path for the outside broadcasting signal through a DC path. A transformer(5) interfaces the audio signal of the broadcasting signal inputted from the DC holding circuit unit(4) with impedance and then inputs to the broadcasting system(3). A relay control circuit unit(6) performs a relay operation according to the polarity voltage supplied through a subscriber line of the key phone system(2) and then supplies the operation power of the broadcasting system(3).
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