Bingo!  Forgot about that! I was treating it like a summing amp, (i.e. same
as applying  minus 1.218 via Ri to the inverting input and connecting V+ to
ground).

At 06:21 PM 2/11/2004 -0300, you wrote:
> > Now, given an gain of 16.166666, to add 19.7 volts to the output requires
>
> > adding 19.7/16.17 = 1.218 volts to the reference input.
>
>
>
>Assuming Rf between Opamp's output and inverting input.
>
>Assuming Ri between Opamp's inverting input and signal input.
>
>V+ applied at the Opamp's non-inverting input
>
>
>
>Don't forget that the gain for the non-inverting input is 1+Rf/Ri (assuming
>Rf as the feedback and Ri as the input), so:
>
>V+ = 19.7 / (1+16.667) = 1.1475V
>
>
>
>I simulated this before post, seemed to work.
>
>
>
>Lucas Hartmann
>
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>

Larry Bradley
Orleans (Ottawa), Ontario, CANADA

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