Placing CircuiTikZ components aligned with respect to their pins

Question

I am using LaTeX with CircuiTikZ to create circuit diagrams. Using the CircuiTikZ documentation and many of questions and answers on this community, I have been able to navigate it pretty well.
I have to recreate an 8 pin DIP chip containig an amplifier symbol connected internally to the pins. I have been able to create it using this code:
begin{tikzpicture}
  % DIP chip
  draw (0,0) node[dipchip,
        num pins=8,
        external pins width=0.3,
        external pad fraction=3,
        hide numbers](C){};
 
  % amplifier
  draw (C) node[op amp, scale=0.571](OA){};
  % amplifier connection to the chip pins
  draw (OA.-) |- (C.bpin 2)
        (OA.+) |- (C.bpin 3)
        (OA.out) |- (C.bpin 6);
end{tikzpicture}

The result is exactly what I wanted:

The main objective in the creation of this image was the alignment between the dipchip pins and the amplifier + and - inputs. I accomplished this by manually resizing the amplifier (as shown by scale=0.571 in the code), until its inputs were perfectly aligned. Being this a quite tedious trial and error task, i was wondering if there is any easier (and possibly more elegant) method to accomplish the same result.
Thank you

Rmano · Answer

The dimension in TikZ are relative to a basic length (which is not accessible easily, which is a bit of a pity), but each element has normally a different way to use the various parameters. So for example the distance between pins in chips is multipoles/dipchip/pin spacing; and the distance between the inputs of an op amp is tripoles/op amp/input height but it is relative to the height of the component (tripoles/op amp/height); this is basically historical.
Then, the components can be scaled by styles (amplifiers/scale and chips/scale)...
So this is what you can have to have the distance between the small amplifiers input match the chips:
documentclass[border=10pt]{standalone}
usepackage[siunitx, RPvoltages]{circuitikz}
% ctikzset{amplifiers/scale=1.5} % this will change the relative sizes
begin{document}
begin{tikzpicture}
    pgfmathsetmacro{myscale}{
        ctikzvalof{multipoles/dipchip/pin spacing}*
        ctikzvalof{chips/scale} /
        (ctikzvalof{tripoles/op amp/height}*
        ctikzvalof{tripoles/op amp/input height}*
        ctikzvalof{amplifiers/scale})
    }
    draw (0,2) node[]{myscale}; % show the magic number
    % DIP chip
    draw (0,0) node[dipchip,
        num pins=8,
        external pins width=0.3,
        external pad fraction=3,
        hide numbers](C){};

% amplifier --- position it relative to the chip
    %(so I can move it around)
    draw (C.bpin 2) node[op amp, scale=myscale, anchor=-](OA){};
    % amplifier connection to the chip pins
    draw (OA.-) |- (C.bpin 2)
        (OA.+) |- (C.bpin 3)
        (OA.out) |- (C.bpin 6);
end{tikzpicture}

end{document}

Notice also that I used relative positioning for the internal op-amp symbol so that you can move the main chip around without changing anything.

Placing CircuiTikZ components aligned with respect to their pins

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