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>
>Thanks Tom,
>
>But I failed to see where the analog input signal is applied.
>
>Paul


This is what I was talking about. The input opamp is used to convert the
input signal to variations in current through the opto LEDs. A V to I
converter. On the other end, the photocurrent is converted back to V either
by a resistor, or an optional buffer amp in I to V configuration.
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