| 摘要 |
PURPOSE:To reduce the installation cost remarkably and to prevent crosstalk of calls of each line, by adding the number of cables in the number of lines by one cable. CONSTITUTION:A plurality of independent cables 2a-2c are connected in parallel with a single common cable 1 tying between transmission and receiving ends, and batteries 3a-3c are inserted to the independent cables 2a-2c. Pairs of telephone sets 4a-4c, 5a-5c, are respectively provided at the transmission and receiving ends of the independent cables 2a-2c to receive DC current from the batteries 3a-3c, and diodes 6a-6c for circulating current blocking are inserted to the independent cables 2a-2c so that the currents flowing to the telephone sets 4a-4c, 5a-5c can entirely be the same direction to the common cable. Thus, the number of cables to be used completed with the number of lines +1 and the circulating current among the lines can be blocked. |
