| 摘要 |
PURPOSE:To ensure the normal extension call with a home telephone slave set even with use of a single telephone IFU regardless of its internal DC resistance, by disposing a capacitor and a constant current circuit in parallel with each other between the telephone IFU and an extension telephone used for call between the IFU and the home telephone slave set. CONSTITUTION:A constant current circuit CV can control its limit current and bypass capacitor C functions to transmit only the sound signal of the call current. While and extension call is carried out between a single telephone IT and a home telephone salve set HT, the circuit CV controls its limit current to supply the sufficient call current to both the telephone IT and the set HT in case the internal DC resistance of the IT is larger or smaller than that of the set HT at an extension call line L of the telephone IT. As a result, the apparent internal DC resistance value of the IT is made coincident with the internal DC resistance of the HT.
|
