| 摘要 |
Apparatus is described for transmitting d.c. signals from an input circuit to an output circuit electrically isolated from the input circuit. Optoelectric coupling is used to achieve the isolation. Photodiodes form the output of the optoelectric couplers, and the photodiodes are connected in series, if more than one coupler is used, and are reverse-biased. Each photodiode has an output terminal connected to an input of an operational amplifier. The input terminals of the amplifier are connected across the fixed ends of a potentiometer, and the variable tap is grounded in common with the ground connection of the amplifier. Positive feedback resistances couple the amplifier outputs to its inputs, and these resistances have values such that the output voltage of the amplifier assumes a value corresponding to the input signal received by the optoelectric couplers.
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