| 摘要 |
PURPOSE:To obtain modulating signals for tremolo effect of a constant period synchronized to key touching by controlling operational amplifier inputs through switch elements according to key touching signals thereby generating the modulating signals. CONSTITUTION:At no the key-touching period, OFF switch elements SW1, SW2 go ON and SW3 goes OFF through inverter N and a slack oscillator is formed by the resistance R1 connected between output terminal and inversion input terminal, the capacitor C connected to inversion input terminal, the resistance R2 connected between the output terminal and non-inversion input terminal, the resistance R3 between the non-inversion input terminal and ground, etc. A specified voltage is applied to the inversion input terminal of an operational amplifier OP and the voltage approximately equal to a reference voltage is applied to the capacitor C. On the other hand, when the elements SW1, SW2 go OFF and SW3 goes ON, the voltage of the capacitor C is applied as a reference voltage to the inversion input terminal of the amplifier OP and the modulating signal of a constant period is generated from the output end of the amplifier OP in synchronization to key touching. |
