| 摘要 |
PURPOSE:To obtain a speech current supplying circuit by which currents can be stably supplied even to an area where speech currents are small. CONSTITUTION:This circuit is equipped with first and second terminals 31 and 32 connected with a 2 line type subscriber's line, which supply direct currents to a terminal, direct current power source 48, and between-line voltage detecting circuit 38 which detects a differential voltage between the voltage of the direct current power source 48 and a voltage between the first and second terminals 31 and 32, and converts it into the currents. Also, the circuit is equipped with a constant current source 53 which generates the currents for supplying a constant voltage between the first and second terminals 31 and 32, and a constant voltage feedback circuit 54 which performs an arithmetic operation by both the output currents of the between-line voltage detecting circuit 38 and the currents of the constant current source 53, and generates the currents for performing the feedback. |
