| 摘要 |
PURPOSE:To confirm the ringing tone generated by a slave unit even at the slave unit side, by using a monitor signal pass filter which leaks a part of the ringing tone sent from the slave unit for the master unit. CONSTITUTION:When a call switch 18 is pushed, the potential of an input terminal 8a of a ringing tone control circuit loweres. Then the rining tone generation control signal is delivered for a certain time from an output terminal 8b to an input terminal 10a of a ringing tone forming circuit. The call signal sent from a rining tone forming circuit 10 is amplified by a low frequency amplifier 4, and a ringing tone is produced through a speaker 2. At the same time, this call signal leaks out partially through a monitor signal pass filter 11 to reach a speaker 17 via a terminal 12 of a master unit A, a terminal 14 of a slave unit B and a DC preventing capacitor 22. A signal path can be formed through an intermediate tap 20b of a hybrid circuit 20, a terminal 20a, a slave unit terminal 15 and a master unit terminal 13 respectively. Thus a ringing tone is produced also through the speaker 17 and is confirmed. |
