| 摘要 |
PURPOSE:To assure the stable control to the amplitude fluctuation of an AC component for a gain controller which extracts the AC component given from a photoelectric microscope, etc., by carrying out a division or multiplication with use of a DC signal corresponding to the amplitude of the AC component of an input signal. CONSTITUTION:An input signal Ei is supplied to a detecting circuit 1 via an AC amplifier 3, and the circuit 1 delivers the DC voltage (P-P voltage) in accordance with the voltage ranging from a peak to another peak of the AC signal component. A setting circuit 2 delivers the voltage proportional to the P-P voltage in case when the P-P voltage is more than a prescribed value, e.g. the value corresponding to the noise component contained in the signal Ei, and delivers a certain level of voltage corresponding to the set voltage when the P-P voltage is less than the prescribed value. The output of the circuit 2 is supplied to a denominator input terminal D of a divider 5. On the other hand, the output of the amplifier 3 is further amplified or attenuated 4 to be supplied to numerator input terminal N. A signal Eo having the amplitude kept at nearly a constant level at all times can be obtained at the output of a divider 5. And the application of the gain control can be excluded to the noise contained in the input signal. |
