| 摘要 |
PURPOSE:To obtain a sufficient output voltage even when a source voltage is low by using a large-current, small-votage amplitude and a small-current, large-voltage amplitude operational amplifier. CONSTITUTION:Charges generated on the surface of a monitor element are converted by an amplifier (A)21 into a voltage, which is rectified 22 and made by a smoothing circuit 23 into a DC voltage proportional to the amplitude of tuning fork vibration. An amplifier A24 has its amplification factor depending upon the smoothing output voltage. When the amplitude of the tuning fork vibration becomes large, charges generated on the monitor element become large, the output voltage amplitude of the A21 increases, and the smoothing output voltage rises; and the amplification factor of the A24 becomes small and the output voltage of the A25 which is applied to a driving element decrease. Consequently, the amplitude of the tuning fork vibration is held constant. |
