| 摘要 |
<p>PURPOSE:To automatically attenuate and control voice, signal sound or alarm sound etc., which is transmitted from the speaker of a telephone terminal in accordance with a telephone terminal state. CONSTITUTION:A call state is detected by a photocoupler PCO or PC1 which is inserted in the call line of a telephone system, the output is added to a buffer circuit IC1 by way of an NOR circuit ICO and a waveform reshaping circuit (a diode D0, resistors R6 and H7, and a capacitor C4), a muting circuit (the resistor R8 and the capacitor C3) is inserted/ejected and the decay quantity of an analog signal inputted from an input terminal AS to an amplifier AMP is controlled.</p> |
