| 摘要 |
PURPOSE:To obtain the constant output of average potential and to enhance the articulation in the display of a wave form, by detecting the average potential of a plurality of differential amplifiers and applying feedback so as not to change the average potential when said amplifiers are changed over in an alternative way. CONSTITUTION:The first amplifier composed of transistors 11-14 and the second amplifier composed of transistors 21-24 are connected to each other in parallel on the output sides thereof and connected to a main amplifier composed of transistors 15-18 on the input side thereof to select the input signals applied to the cathode ray tube of an oscilloscope by change-over voltages V1, V2 and V3, V4 in an alternative way. The middle point between resistors 41, 42 is connected to one terminal of a comparator 32 and reference voltage 31 is connected to the other terminal thereof and the output of the comparator 32 is connected to the middle point between resistors 43, 44 to form a feedback circuit so that the average voltage of the outputs of the selected amplifiers becomes constant and the average output to the cathode ray tube is kept constant.
|
