| 摘要 |
PURPOSE:To attenuate even a large voice input signal without deterioration in the S/N by providing a phase inversion circuit converting a phase of an output of an impedance conversion circuit and feeding back the result to a converter unit to the attenuator and applying a signal whose phase is inverted to the converter unit. CONSTITUTION:The pre-stage attenuator for a display proportional transducer provided with an impedance conversion circuit 21 in which an output voltage of a converter unit 1 is proportional to a displacement of a vibrator is provided with a phase inversion circuit 23 converting the phase of the output of the impedance conversion circuit 21 and feeding back the result to the converter unit 1. Then the connection between the phase inversion circuit 23 and the converter unit 1 is turned on/off by a switch 35. Thus, the signal whose phase is inverted by the phase inversion circuit 23 is applied to the converter unit 1, the sensitivity of the converter unit 1 is decreased and the output of the converter unit 1 converted into a low impedance is substantially attenuated. |
