\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows}
\usetikzlibrary{positioning}
\usetikzlibrary{calc}
\begin{document}
\tikz \fill[green] rectangle (0.5,0.5); Something
    about something.

  \begin{tikzpicture}
     \draw [solid] let \p{I} = (0,0) in (1,1) -|
        (\x{I}-1cm,-1cm) node [yshift=-.25cm] {(i)};
     % Just some comment
     \end{tikzpicture}

     \begin{tikzpicture}
% (i) center contact head
\draw [solid] let \p{I} = (centerContactHead) in (centerContactHead) -|
  (\x{I}-.75cm,-2.5)
  node [yshift=-.25cm] {(i)};

% (ii) outer conductor of the contact head
  \coordinate (outerContactHead) at (.8,-1.7);
  \draw [solid] let \p{O} = (outerContactHead)
    in (outerContactHead) -- (\x{O},-2.5)
      node [yshift=-.25cm] {(ii)};

\begin{axis}
  \addplot
    table[row sep=crcr]{%
      0       0\\
      1       1\\
      2       2\\
    };
  \end{axis}
     \end{tikzpicture}

\begin{center}
    \begin{circuitikz}[american]
        \draw (0,0) node[npn]{};
    \end{circuitikz}
  \end{center}
\begin{center}
    \begin{circuitikz}[american, baseline=(VCC)]
        \draw (0,0) node[npn]{};
\end{circuitikz}
\end{center}

\end{document}
