| 摘要 |
PURPOSE:To secure stability in linear operation in dialing by performing side-tone improvement of a low frequency in calling, by connecting a transmitter and the 2nd balancing circuit to the break contact of a push-button dial common switch via diodes. CONSTITUTION:To transmitter T and the 2nd balancing circuit ZN2, diodes D1 and D2 are connected respectively and common connection terminal P2 of diodes D1 and D2 is connected to break contact B of push-button dial common switch SW. As a result, a side tone of a low frequency is improved by the 2nd balancing circuit ZN2 in calling as well as a conventional telephone set circuit and the 2nd balancing circuit ZN2 large in current bleed is disconnected even from a long distance line in dialing, thereby securing stability in linear operation. Further, transmitter T is electrically disconnected from the 2nd balancing circuit ZN2 by diodes D1 and D2, so that the level variation of a dial signal due to a change in the resistance of transmitter T will be inhibited. |
