| 摘要 |
PURPOSE:To avoid the production of an abnormal sound when a gate is switched, by providing a muting circuit for a plurality of applications of a variable resistor using a hold-through gate. CONSTITUTION:When a switch S4 turns on and a switch S5 turns off, a hold- through gate 7 is in a through-state and a flip-flop 6 waites for input. A variable resistor 1 is operated as a sound volume adjuster. A state just before the operation of the switches S4 and S5 is given from a hold-through gate 7' to a tone controlling circuit. If a variable resistor 1 is set to a value greater than a reference value of a comparator 4, the flip-flop 6 is at low level and an attenuator 10 is controlled to be muted. As a result, a large sound when the switches S4 and S5 are operated can be prevented. |
