| 摘要 |
PURPOSE:To increase the length of a cable for signal transmission between a main device and a telephone set by supplying electric power through the cable. CONSTITUTION:A voice signal is transmitted from a voice signal terminal 5 connected to a switch circuit through a transformer 8, a wiring cable 3, a transformer 10, and a talking circuit 13. Data, on the other hand, are transmitted between the data transmitting and receiving circuit 6 of a main device 1 and the data transmitting and receiving circuit 15 of a telephone set 2 through a transformer 9, a cable 4, and a transformer 11. Further, electric power supply from the main device 1 to the telephone set 2 is carried out by a main device power source 7 through center taps of the transformers 8-11 to power up a power receiving circuit 12. |
