Circle with a fill in CircuiTikz

Question

I have a schematic that I'm trying to draw. It uses a custom symbol which is not listed in CircuiTikz manual. It should basically be a circle with 'N' in it.

My current code is:

\begin{circuitikz}
    \draw
        (0, 0) to[sV] (0, 6)
        (0, 6) -- (7, 6)
        (7, 6) -- (7, 5)
        (7, 5) to[R] (5, 3)
        (5, 3) to[R] (7, 1)
        (7, 1) -- (7, 0)
        (7, 0) -- (0, 0)
        (7, 1) to[R] (9, 3)
        (9, 3) to[R] (7, 5)
        (5, 3) -- (7, 3)
        circle [radius = 10pt]
        (7, 3) -- (9, 3) 
        ;
\end{circuitikz}

The image it produces is:

However, I can't make a circle without these lines in it and I don't know how to add an 'N' in the middle.

Answer 1

Since the circle is already drawn, adding an N inside is not that difficult. One approach consists in adding a node:

\documentclass [tikz,border=10pt]{standalone}
\usepackage{circuitikz}

\begin{document}

\begin{circuitikz}
    \draw
        (0, 0) to[sV] (0, 6)
        (0, 6) -- (7, 6)
        (7, 6) -- (7, 5)
        (7, 5) to[R] (5, 3)
        (5, 3) to[R] (7, 1)
        (7, 1) -- (7, 0)
        (7, 0) -- (0, 0)
        (7, 1) to[R] (9, 3)
        (9, 3) to[R] (7, 5)
        (5, 3) -- (7, 3)
        circle [radius = 10pt]node[circle,fill=white,minimum size=10pt]{N}
        (7, 3) -- (9, 3) 
        ;
\end{circuitikz}

\end{document}

The result:

Another alternative, equivalent to the first one, but more elegant is:

\begin{circuitikz}
    \draw
        (0, 0) to[sV] (0, 6)
        (0, 6) -- (7, 6)
        (7, 6) -- (7, 5)
        (7, 5) to[R] (5, 3)
        (5, 3) to[R] (7, 1)
        (7, 1) -- (7, 0)
        (7, 0) -- (0, 0)
        (7, 1) to[R] (9, 3)
        (9, 3) to[R] (7, 5)
        (5, 3) -- (7, 3)
        node[draw,circle,fill=white,minimum size=10pt]{N}
        (7, 3) -- (9, 3) 
        ;
\end{circuitikz}