| 摘要 |
PURPOSE:To obtain a volume adjusting circuit, for which electronic control is easy, by providing a charging circuit to a capacitor having cases that first and second transistors are conducted by receiving a rhythm signal and that the first transistor is conducted. CONSTITUTION:Equivalent resistance value is changed in a state that transistors T1 and T2 to charge a capacitor C by the rhythm signal are conducted. Then, charging quantity to the capacitor C is adjusted. In the case of a large tone, a rhythm signal 1 simultaneously goes into A1 and A2 and a reverberative waveform 2 is made. Then, a modulated waveform 4 goes into an amplifier circuit AMP. In the case of a small tone, a rhythm signal 1' is inputted only to the A1. Then, since the rhythm signal 1' is not inputted to the A2, only the transistor T1 is in the conductive state. Thus, it is not necessary to use comparatively expensive parts such as a variable resistor or switch, etc., and simultaneously, the volume adjusting circuit, for which mechanical operation is not required and the electronic control is easy, is obtained. |
