| 摘要 |
PURPOSE:To eliminate the residual characteristic and the level characteristic of the mechanical filter, by holding the peak value of the input signal and by adjusting automatically the trigger level of the Schmitt trigger circuit according to the peak value. CONSTITUTION:When the voltage converted to a DC is applied to terminal 17, diode CD1 becomes conductive, and the peak value divided by resistances R1 and R2 is charged to capacitor C1. When the voltage of capacitor C1 is applied to the + side input terminal of amplifier A2, diode CD2 becomes conductive. The reference voltage is applied to the - side input terminal of amplifier A3 if the output voltage of this switch circuit 16 is lower than the reference value, and the voltage of capacitor C1 is applied to it if the output voltage of circuit 16 is larger than the reference voltage. This voltage becomes the trigger level of the Schmitt trigger circuit, and the output of circuit 6 becomes H-level if the voltage from terminal 17 is larger than this trigger level, and the output of circuit 6 becomes L-level if the voltage from terminal 17 is smaller than the trigger level. Consequently, since a trigger level is selected according to the level of the control signal, the level margin can be extended. |
