CircuitTikZ: Change wire thickness for single wire(s)

Question

while being used to using LaTeX for several years now, I am fairly new to using CircuitTikZ. I was wondering if it is possible to change the wire size of only one (/some) wire(s) in a circuit like in the following example:

My MWE for drawing the circuit would be

\documentclass[10pt, a4paper]{article}
\usepackage[siunitx]{circuitikz}

\begin{document}

    \begin{circuitikz}[european]
        \draw (0,0) to[sinusoidal voltage source,label=$U$] (0,3) to[short, -*] (2,3) 
          to[lamp, l=$G$] (2,0) to[short, *-] (0,0);
        \draw (2,3) -- (4,3) to[short, l=$R$] (4,0)-- (2,0);
    \end{circuitikz}

\end{document}

And, I hope this is allowed to do here, I have a second question regarding the symbol of the voltage source: Does anyone know if there is a voltage source symbol consisting of the to empty circles like in the image above?

Kind regards and thank you for your help

Adrian

Answer 1

\documentclass[10pt, a4paper]{article}
\usepackage[siunitx]{circuitikz}

\begin{document}

    \begin{circuitikz}[european]
        \draw (0,0) to[sinusoidal voltage source,label=$U$] (0,3) to[short, -*] (2,3) 
          to[lamp, l=$G$] (2,0) to[short, *-] (0,0);
        \draw [line width=3pt](2,3) -- (4,3) to[short, l=$R$] (4,0)-- (2,0);
    \end{circuitikz}

\end{document}

Answer 2

Line thickness is a property of a path, so you need two different paths to have a different line thickness.

You have to consider too that several elements in circuitikz are affected by line thickness (for example, the sample lamp thing has line thickness that depends on the underlying line thickness).

You can do a game of mix and match by using line width and the component class styling (see the manual on page 32 and following). I like to keep that changes into scope environments.

\documentclass[border=5pt]{standalone}
\usepackage[siunitx, RPvoltages]{circuitikz}
\begin{document}

    \begin{circuitikz}[european]
        % thin line thing
        \draw (2,0) -| (0,1) to[open, o-o, l=$U$] (0,2) |- (2,3);
        % standard line width is 0.4pt. We go to double it
        \begin{scope}[line width=0.8pt]
            % lamp is a misc element: we can have it standard thickness with this
            \ctikzset{misc/thickness=1}% default is 2
            \draw (2,0) to[lamp, *-*] (2,3) -- (4,3) to [short, l=$R$] (4,0) -- (2,0);
        \end{scope}
    \end{circuitikz}

\end{document}

Notice that I faked your "generator" with a short, o-o element. There is an double-circle generator in the package, but it's quite different: