| 摘要 |
PURPOSE: To miniaturize the speaking current supplying circuit and to mount it with high density by suppressing the generation of heat at a feeding transistor concerning the speaking current supplying circuit for a subscriber circuit. CONSTITUTION: Since equivalent feeding resistance has a fixed value regardlessly of the level of load resistance (line resistors RLA and RLB+ telephone function resistor Rlγ ), when supplying a speaking current to a subscriber in a short distance, that current is enlarged but when supplying that current to a subscriber in a long distance, it is reduced. Therefore, the subscriber circuit housing the subscriber in the short distance generates large power consumption and most of that power is consumed by feeding transistors 3 and 4. Therefore, the generation of heat is distributed by inserting resistors R7 and R8 having the resistance values within a certain range not to saturate any transistor at the midpoint of the respective collectors of the feeding transistors 3 and 4, switches SA and SB and resistors R4 and R5. |
