| 摘要 |
<p>PURPOSE:To prevent the occurrence of uncomfortable abnormal sound generated at the time of power-on by combining an electronic volume circuit and a power-on detecting circuit to give muting operation functions to the electronic volume circuit. CONSTITUTION:When a power source is turned on, the delay of voltage rise at a voltage diving point 5b of a delay voltage rising circuit 5 is used to generated a control signal, which cuts the operation of an electronic volume 4, from a muting circuit 6 during a certain period corresponding to this delay and a signal is prevented from being inputted to a power amplifier 3 during this certain period. The electronic volume circuit 4 and a power-on detecting circuit are combined to give the muting operation functions to the electronic volume circuit 4 in this manner. Thus, the occurrence of uncomfortable abnormal sounds generated at the time of power-on is prevented.</p> |
