| 摘要 |
PURPOSE:To inform the calling state, by providing a bridge rectifier circuit outputtig a rectifier voltage in response to a calling signal transmitted from a handset of an opposite party, and driving a DC buzzer with this rectified voltage. CONSTITUTION:In turning on a switch 27, a voltae Vp is outputted from a power supply 28 and this voltage is applied to terinals 13, 14 of the opposite party as a calling signal. This voltage Vp can be either AC or DC. Further, a switch 22 is turned off so as not to energize a buzzer 24 of the caller side. This switch 22 can be interlocked with the switch 27. A rectified output voltage is obtained from a rectifier circuit 19 of the opposite party applied with the voltage Vp, this voltage is applied to a DC buzzer 24 via the switch 22 turned on and a resistor 23, and applied to a light emitting diode 26 via a resistor 25. Thus, the buzzer 24 is energized, the light emitting diode 26 is illuminated and the calling state is informed. |
