| 摘要 |
PURPOSE:To obtain a simple and low-cost interphone device by installing the DC power source common to plural units of talking devices plus ringing tone generator which gives the waveform conversion to the output of the power source. CONSTITUTION:Talking devices 11-1n possess ringing tone and transmission speaker SP1, the reception speaker and channel selection switch Sij (i, j=1, 2...n), and carry out the talking among the optional talking devices. And DC power source 2 and waveform converter 3 for generation of the ringing tone are connected in common to those talking devices. And if the handset is taken up with talking device 11, switches S1-S3 switch from the positions shwon in the diagram. After this, speaker SP1 within device 12 is connected to converter 3 via switches S12 and S1 within device 11 and with operation channel selection switch S12, and thus the ringing tone is generated at device 12. When the handset is picked up with device 12, switches S1-S3 within device 12 are switched. Thus the talking becomes possible between devices 11 and 12. |
