| 摘要 |
PURPOSE:To reduce sound distortion or sensible noise by inserting a diode to a pre-stage of a voltage-current converting circuit converting a divided voltage between a power terminal and a terminal of a telephone set into a DC current flowing between the two terminals so as to avoid the clipping of a waveform with respect to an excess input. CONSTITUTION:A feeder circuit is constituted between power terminals 101, 105 and telephone set terminals 103, 107. Voltage division circuits 111, 121 output the voltage division voltage between the two terminals. Smoothing circuits 113, 123 smooth the output voltage of the circuits 111, 121. Voltage-current conversion circuits 115, 125 convert the output voltage of the smoothing circuits 113, 123 into the DC current flowing between the two terminals. Through the constitution above, diodes 117, 127 are inserted respectively to the pre-stage of the voltage-current conversion circuits 115, 125. Thus, the DC voltage between the terminals of the feeding circuits 110, 120 is the sum of the base-emitter voltage of the circuits 115, 125 and the forward voltage of the diodes 117, 127 in response to the AC input and the clipping strength of the waveform with respect to the excess optical input is improved. |
