| 摘要 |
PURPOSE:To eliminate bad influences to adjacently installed circuits of other subscribers at the time of sending a call signal, by sending the call signal to the telephone set of a subscriber from the midpoint of the primary winding of a repeating coil through the primary winding. CONSTITUTION:A call signal is sent to a line A of a subscriber's line L1 through a contact (r) provided between the midpoint N1 of a repeating coil TR1 and a resistance R1 and the primary winding of the TR1. Therefore, a transient voltage generated when the call signal is interrupted intermittently by the contact (r) at the time of sending the call signal, is attenuated by the inductance of the primary winding of the TR1, and induced noises to adjacent subscriber's circuits are sharply reduced. Moreover, since the line A side is also earthed through a resistance 3 and a call signal source RG, the degree of unbalance against the ground of the subscriber's circuit sending the call signal is sharply improved, and the induction of the high voltage and transient voltage sent from the subscriber's circuit to a subscriber's line L2 is also improved. |
