PURPOSE: To convert a balance input signal including the external noise into an unbalance signal, by giving a division of voltage to an input signal of the balance input signal and then connecting the input signal to both the forward phase input terminal and the reverse phase input terminal of an operational amplifier.
CONSTITUTION: At the circuit correspondence part of an electronic switchboard, one of balance input signals V1 and V2 receives a division of voltage to be connected to the forward phase input terminal of an operational amplifier A. While the other balance input signal receives divisions of voltage R5 and R6 to be connected to the reverse phase input terminal 1 of the amplifier A via resistances R1 and R2. Then the terminal 1 is connected to an output terminal 3 of the amplifier A by a resistance R4 to deliver the difference of the balance input signals.
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KOBAYASHI TAKAKI
MINAMITANI EIJI
