| 摘要 |
PURPOSE:To improve the quality of voice, by switching the least threshold potential level of an electronic telephone set circuit in response to the voltage level of a voice signal so as to secure the dynamic range of the voice signal, and to increase the range. CONSTITUTION:A transmitting/receiving amplifier circuit TR, a DC-DC converter CONV, a switching circuit SW and a constant current source circuit S are provided, and the switching circuit SW consists of a switching element Q1 connecting the amplifier circuit TR and the circuit S and a switching element Q2 connecting a resistor R6 and the CONV. When a voltage of the telephone set is a prescribed value or over, the element Q1 turns on and when it is below the prescribed value, the element Q2 turns on. |
