| 摘要 |
PURPOSE:To improve the side tone attenuation properties without increasing the DC resistance of the circuit but by inserting the capacitance in parallel to the telephone circuit. CONSTITUTION:When the impedance is set to ZO when viewing the side of cable 2 from telephone 1 in case capacitance 4 is not inserted into the circuit, the balance is lost between telephone 1 and the talking circuit if ZO features a high impedance. Thus capacitance 4 is inserted in parallel to the circuit, impedance Zin features as Zin=ZO/(1+jomegaC.ZO) when viewed from telephone 1. Accordingly, the impedance can be lowered at the line side when viewed from telephone 1, thus securing the balance between telephone 1 and the talking circuit. |
