| 摘要 |
PURPOSE:To make an externally-fitted high-pressure resistance capacitor unnecessary by subtracting a flyback loop's LPF output voltage for generating a subscriber's line DC feed resistance from a difference between a voltage between the lines of the subscriber's line and a supply voltage, into an input of a low voltage level circuit. CONSTITUTION:An output signal of a detection circuit 3 and an output signal of an LPF7 are subtracted by a circuit 12 and inputted to a low voltage level circuit 11, out of a voltage of a difference between a supply voltage which is not shown in the figure and a signal voltage between subscriber's lines 1 and 2 including DC and AC detected by a circuit 3, which makes a high-pressure resistant capacitor for cutting the AC, thereby making it suitable for all electronizing circuits. |
