| 摘要 |
PURPOSE:To prevent AC fluctuation of a power supply transistor (TR) by connecting one terminal of a capacitor to a base of the power supply TR and connecting the other terminal of the capacitor to an output terminal or ground. CONSTITUTION:Hooking off a handset 5, a diode bridge circuit 3 gives a voltage with a definite polarity to a talking circuit 4 and a power supply circuit 8. On the other hand, the power supply TR 9 is turned on by a voltage fed to an input terminal A of the circuit 8 and a desired operating current is given to an output terminal B to be fed to a control circuit 6. The fluctuation of the power supply TR 9 due to AC is prevented by the capacitor 12 and a 2nd resistor 11 against the AC applied from a telephone line and the reduction in the AC impedance is not caused due to the increase in the current attended with the voltage increase.
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