Add current paths in circuitikz

Question

This is my code:

\documentclass[]{article}
\usepackage{circuitikz}
\begin{document}
\begin{figure}
\centering
\begin{circuitikz}
\draw (0,0) 
  to[short,o-](2,0)
  to[short,*-](4,0)
  to[D](4,2)
  to[D](4,4)
  to[short,-*](2,4)
  to[short,-o](0,4);
\draw (4,0) 
  to[short,*-](8,0)
  to[D](8,2)
  to[D](8,4)
  to[short,-*](4,4);
\draw (2,0)
  to[Tnpn,n=q2](2,2)
  to[Tnpn,n=q1](2,4);
\draw (8,0)
  to[short,*-](10,0)
  to[Tnpn,n=q4,mirror](10,2)
  to[Tnpn,n=q3,mirror](10,4)
  to[short,-*](8,4);
\draw
  (q1.B) to[short,-o](1,3) node[left]{$Q_1$}
  (q2.B) to[short,-o](1,1) node[left]{$Q_2$}
  (q3.B) to[short,-o](11,3) node[right]{$Q_3$}
  (q4.B) to[short,-o](11,1) node[right]{$Q_4$};
\draw (2,2) to[short,*-*](4,2) to[Telmech=M](8,2) to[short,*-*](10,2);
\end{circuitikz}
\caption{Chopper E}
\end{figure}
\end{document}

I want to know if there is the possibility, using circuitikz, of drawing the path of current and general potential line (general in the sens that they don't have to refer to a particular bipole but to two general point).

Also, is possible for the currect path to be behind the circuit?

Note: I'm looking for a functionality of circuitikz package. But if not, also a solution with tikz would be ok, but preferably without loading the circuit tikz library or I have to modify a lot of figures for compatibility reasons.

Answer 1

\documentclass[]{article}
\usepackage{circuitikz}
\usetikzlibrary{decorations.markings}

\begin{document}
\begin{figure}
  \centering
  \begin{circuitikz}
    \draw (0,0) node (N5){}
    to [short,o-](2,0) 
    to[short,*-](4,0)
    to[D](4,2)
    to[D](4,4)
    to[short,-*](2,4) node (N1){}
    to[short,-o](0,4) node (O){}; 
    \draw (4,0) 
    to[short,*-](8,0) 
    to[D](8,2)
    to[D](8,4)
    to[short,-*](4,4);
    \draw (2,0)
    to[Tnpn,n=q2](2,2) node(N2){}
    to[Tnpn,n=q1](2,4);
    \draw (8,0)
    to[short,*-](10,0) node(N4){}
    to[Tnpn,n=q4,mirror](10,2)
    to[Tnpn,n=q3,mirror](10,4)
    to[short,-*](8,4);
    \draw
    (q1.B) to[short,-o](1,3) node[left]{$Q_1$}
    (q2.B) to[short,-o](1,1) node[left]{$Q_2$}
    (q3.B) to[short,-o](11,3) node[right]{$Q_3$}
    (q4.B) to[short,-o](11,1) node[right]{$Q_4$};
    \draw (2,2) to[short,*-*](4,2) to[Telmech=M](8,2) to[short,*-*](10,2) node(N3){};
    % adding current
    \begin{scope}[very thick,decoration = {
        markings,
        mark = at position 0.05 with {\arrow{>}}}
    ] 
    \draw[line width = 3pt, red, opacity = 0.4, postaction = {decorate}] (O.north) -- 
    (N1.north east) node[above, midway, opacity = 1]{$i$} -- (N2.north east)
    -- (N3.north west) -- (N4.north west) -- (N5.north) ;
    \end{scope}
    % adding voltage
    \draw[line width = 3pt, red, opacity = 0.4, ->] (N5) to[out = 150, in = 210] (O) node[left, opacity = 1]{$V$};
  \end{circuitikz}
  \caption{Chopper E}
\end{figure}
\end{document}

EDIT To place the current on the background layer, add \usetikzlibrary{backgrounds} in the preamble, and on background layer as an option of the scope environment. Also changed the path following @ Kpym's suggestions

\documentclass[]{article}
\usepackage{circuitikz}
\usetikzlibrary{decorations.markings}
\usetikzlibrary{backgrounds}

\begin{document}
\begin{figure}
  \centering
  \begin{circuitikz}
    \draw (0,0) node (N5){}
    to [short,o-](2,0) 
    to[short,*-](4,0)
    to[D](4,2)
    to[D](4,4)
    to[short,-*](2,4) node (N1){}
    to[short,-o](0,4) node (O){}; 
    \draw (4,0) 
    to[short,*-](8,0) 
    to[D](8,2)
    to[D](8,4)
    to[short,-*](4,4);
    \draw (2,0)
    to[Tnpn,n=q2](2,2) node(N2){}
    to[Tnpn,n=q1](2,4);
    \draw (8,0)
    to[short,*-](10,0) node(N4){}
    to[Tnpn,n=q4,mirror](10,2)
    to[Tnpn,n=q3,mirror](10,4)
    to[short,-*](8,4);
    \draw
    (q1.B) to[short,-o](1,3) node[left]{$Q_1$}
    (q2.B) to[short,-o](1,1) node[left]{$Q_2$}
    (q3.B) to[short,-o](11,3) node[right]{$Q_3$}
    (q4.B) to[short,-o](11,1) node[right]{$Q_4$};
    \draw (2,2) to[short,*-*](4,2) to[Telmech=M](8,2) to[short,*-*](10,2) node(N3){};
    % adding current
    \begin{scope}[on background layer, very thick,decoration = {
        markings,
        mark = at position 0.05 with {\arrow{>}}}
    ] 
    \draw[line width = 3pt, red!40, postaction = {decorate}] (O.north)
    -- node[above, red]{$i$} (N1.north east) |- (N3.north west) |-
    (N5.north); 
    \end{scope}
    % adding voltage
    \draw[line width = 3pt, red!40, ->] (N5) to[out = 150, in = 210]
    (O) node[left, red]{$V$};
  \end{circuitikz}
  \caption{Chopper E}
\end{figure}
\end{document}

Answer 2

Here an implementation with almost 90% of circuitikz macros, with all styles options, the current lines are part of the tikz macros and the decorations library. An observation is that the notation of the voltage is wrong in your drawing, the current moves towards the positive voltage.

OBS: I compile in the standalone class, since I export the result in pdf, and then I import it into the main document through the graphicx library that allows to insert pdf documents you can see a more tedious explanation here.

RESULT:

MWE:

% By j.leon.v
\documentclass[border=30pt]{standalone}
\usepackage{tikz}
\usepackage{circuitikz}
\usetikzlibrary{decorations.markings}
\begin{document}
\ctikzset{bipoles/length=.8cm}
\begin{tikzpicture}[line width =.75pt,
    current1/.style ={
        line width=2pt,
        color=red,
        opacity=.3,
        postaction={decorate,decoration={
            markings,
            mark=between positions 0.25 and 1 step 1cm with{
                \arrow[red,line width=.8mm]{latex}}
            }
        }
    },
    current2/.style ={
        line width=2pt,
        color=red,
        opacity=.3,
        postaction={decorate,decoration={
            markings,
            mark=between positions 0.03 and 1 step 1cm with{
                \arrow[red,line width=.8mm]{latex}}
            }
        }
    },
    ]%TIKZ PICTURE PREAMBLE
% Draw transistors as objets
    \draw(2,3) node[npn,
        scale=1.5,
        line width=1.5pt,
        color=red
        ](q1){};

    \draw(2,1) node[npn,
        scale=1.5,
    %   line width=1.5pt,
        color=black
        ](q2){};

    \draw(9,3) node[npn,
        scale=1.5,
    %   line width=1.5pt,
    %   color=red,
        xscale=-1
        ](q3){};

    \draw(9,1) node[npn,
        scale=1.5,
        line width=1.5pt,
        color=red,
        xscale=-1
        ](q4){};

%Draw energy lines
    \draw(-0.5,4) node[ocirc,
        scale=1.5,
        line width=1.5pt,
    %   color=red
        ](L1){};

    \draw(-0.5,0) node[ocirc,
        scale=1.5,
        line width=1.5pt,
    %   color=red,
        ](L2){};


%Draw the motor     
    \draw[color=red,line width=1.5pt](4.5,2) coordinate (M1)
        to [Telmech=M,red](6,2) coordinate (M2);


%Draw diodes:
    \draw (7,0) to[D*,*-*](7,2)to[D*,*-*](7,4);
    \draw (3.5,0) to[D*,*-*](3.5,2)to[D*,*-*](3.5,4);

% Draw pasive wire
    \draw(q1.E|- M1) to [short,*-] (M1);
    \draw(q4.C|- M2) to [short,*-] (M2);
    \draw (q2.C) -- (q1.E);
    \draw (q4.C) -- (q3.E);
    \draw (L1) -| (q3.C);
    \draw (L1) to[short,-*](L1-|q1.C) -- (q1.C);
    \draw (L2) to[short,-*](L2-|q2.E) -- (q2.E);
    \draw (L2) -| (q4.E);

% Draw the path of the electric current.
    \draw [current1] (L1) -| (q1.C);
    \draw [current2] (q1.E) |- (M1);
    \draw [current1] (M2) -| (q4.C);
    \draw [current2] (q4.E) |- (L2);

% Draw labels
    \draw
      (q1.B) to[short,-o,red](q1.B) node[left]{$Q_1$}
      (q2.B) to[short,-o](q2.B) node[left]{$Q_2$}
      (q3.B) to[short,-o](q3.B) node[right]{$Q_3$}
      (q4.B) to[short,-o](q4.B) node[right]{$Q_4$};
    \draw (L1)node[left]{$-$};
    \draw (L2)node[left]{$+$};

\draw[color=red,line width=1.5pt] (L1) to [open,v=$Vin$] (L2);

\end{tikzpicture}
\end{document}