how to draw double circle nodes in tikz more clear?

Question

I like the drawing final states in Peter Linz's Book, more clear than final states in tikz. can do it with apply an option in tikz, or other packages?

Answer 1

You could use the double option in TikZ. The separation distance between the lines can be adjusted using double distance.

\documentclass{standalone}
\usepackage{tikz}
\begin{document}
\tikz \draw [double, double distance=1pt] (0,0) circle (14pt);
\end{document}