| 摘要 |
PURPOSE:To understand the increase/decrease result of sound volume during a muting process by releasing the operation of a sound erasing means which discontinues the sound output by means of a muting switch in response to the operation of a sound volume increasing/decreasing means. CONSTITUTION:When a muting operation button 4 is pushed, a muting discriminating circuit 9 produces an output. Then the output Q of an FF10 is set at 1, and the voltage is produced at the output of a gate circuit 17 to minimize the sound volume regardless of the output voltage of a sound volume switching circuit 11. Thus the sound volume is erased. When the sound volume increase/ decrease operation buttons 2 and 3 are pushed, an output 1 is produced at discriminating circuits 7 and 8 respectively. The FF10 is reset by the output 1 via an OR circuit 15, and the output Q is set at 0. Thus the output voltage of the circuit 11 emerges as it is at the output of the circuit 17, and the voltage which minimizes the sound volume does not emerge any more. |
