| 摘要 |
Current regulating elements(10) limit the current flowing in the telephone cct.(18,20) to 40 mA. A reference voltage generator(12) has a reference voltage(Vref) on its output according to the input setting(S1-Sn) to it. The output from the reference voltage generator(12) is fed into the voltage supply electronic cct.(10) which directly controls the voltage and current applied to the telephone cct.(18,20). The control is initiated when further circuitry(22,24) detects the lifting of the telephone handset(1). Off-hook condition initiates control via a feedback of level information from the two wire/four wire amplified hybrid(42) with control connection(S1 - Sn) into the main input control to the voltage generator controlling the local line. |
