| 摘要 |
PURPOSE:To provide the current supply circuit in which the AC impedance is balanced by forming the current supply circuit to a telephone set with a specific constant current circuit, a resistor and a capacitor or the like. CONSTITUTION:A voltage applied to a 1st constant current circuit 1 and a 2nd constant current circuit 2 is always set higher than O even if the current adjusting circuit is not provided. Thus, it is prevented that the two constant current circuits 1, 2 are saturated (its voltage is close to 0) and the AC impedance (impedance against an AC current) is decreased, and a sufficiently high AC impedance is always given to a 1st resistor 3 and a 2nd resistor 4. Moreover, let the resistance of the resistors 3, 4 be respectively R1, R2 (R1=R2), since the AC impedance when viewing from a telephone set circuit 7 is only the resistance R1 (R2) between terminals, the AC balance is taken. |
