| 摘要 |
PURPOSE:To prevent efficiently a side tone with a simple constitution by connecting an impedance circuit obtained by connecting a capacitor to a resistor in series between a T-type bridge circuit and a transformer in parallel with the transformer. CONSTITUTION:An AC equivalent circuit in an insulating transformer 4 is obtained by inserting a winding resistor 41 and a leakage indactance 42 into a subscriber's line in series and inserting a main indactance 43 between line terminals 5a and 5b in parallel. In the low frequency range, the impedance of a capacitor 10b in the impedance circuit 10 is increased as if the reduction of impedance of the main indactance 43 is offset. In the high frequency range, the indactance 11a of an impedance circuit 11 is increased, so that the increment of the indactance 42 is corrected by the increment of the indactance 11a. Similarly, the winding resistor 41 in the transformer is corrected by a resistor 11b. |
