| 摘要 |
PURPOSE:To accurately measure difference voltage very small as compared with absolute voltage, by alternately changing over two input voltages by an analogue switch and inputting the same to an amplifier through a coupling condenser. CONSTITUTION:Two voltages V1, V1+DELTAV having DC difference voltage are respectively inputted to the input terminals 11, 12 of an analog switch 1 and a change-over pulse generator 2 is connected to a switch change-over terminal 13. When the duty of a change-over pulse is set to 50%, the voltages V1, V1+DELTAV alternately appear in the output terminal 14 of the analog switch 1 at every 1/2 cycle and the output of said switch 1 is inputted to the input terminal 41 of an amplifier 4 through a coupling condenser 3. As a result, a pulse V0 having amplitude of (1+R2/R1)DELTAV is outputted to the output terminal 42 of the amplifier 4 and measured by an AC voltmeter 5 to measure the difference voltage of the two inputs.
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