| 摘要 |
PURPOSE:To decrease the click sound and to confirm the dial tone after release of the call stop by connecting the earphone and the cpacitor in series when the pulg is inserted into the jack and connecting the lamp to the channel circuit via push- button switch when the plug is pulled out of the jack respectively. CONSTITUTION:Push-button switch 2 is always open and connected in series to lamp 1 to be furthermore connected in parallel to the channel circuit along with the series circuit comprising jack 3 and capacitor 4. When plug 5 connected to earphone 6 is inserted to jack 3, both capacitor 4 and earphone 6 are connected in series to the channel circuit; and only lamp 1 is connected to the channel circuit with push of switch 2 when plug 5 is pulled out of jack 3. In this way, the click sound caused at the monitoring time can be decreased, and also the factor causing the error pulse and others can be eliminated. And thus the dial tone can be confirmed after release of the call stop. |
