| 摘要 |
PURPOSE:To prevent a line wire loop from closing during connecting an extension and connect the line wire only by an off hook by disposing an isolation means for separating serially the extension and the line wire in a main device in a home telephone device. CONSTITUTION:By performing an off-hook of a telephone set 6, an optical diode 26 lights, and an output of a photocoupler 23 goes to L. Under this state, luminescent diodes 18, 26 flash, an output of an photocoupler 11 is inputted to a transmission control section 15 and the output of the photocoupler 23 is inputted to an arithmetic control section 27. In the arithmetic control section 27, in accordance with the output of the photocoupler 23, the dial data is stored, after a predeterminedtime, a relay driving section 28 is controlled, and a dial pulse is transmitted to an exchange line 3. When an extension key 14 is operated, the extension calling data is transmitted to a transmission control section 33 through a data line 4. In the control section 33, the relay driving section 28 is controlled and contacts r31, r32 are changed over to an extension circuit 22. |
