File:BraunTube01.svg

\documentclass[crop,border=5,tikz,convert={outext=,
  command=\unexpanded{pdf2svg \infile\space\outfile\%02d.svg
    all}},multi=false]{standalone}
\usetikzlibrary{math,calc,through,shapes,patterns,decorations.pathmorphing,intersections,circuits.ee.IEC}
%\usepackage{tikz-3dplot}
\usepackage{pifont}

\newcommand{\egun}[2]{
  \draw[ultra thick,gray!50,rounded corners]
  (-0.5,0.9)--(-3.1,0.9)--(-3.1,-0.9)--(-0.5,-0.9)--(7.95,-3)--(7.95,3)--cycle;

  \draw[very thick,green!50!black] (-2.7,0.7)-|(-2.1,0.15)node[above right]{\ding{173}};
  \draw[very thick,green!50!black] (-2.7,-0.7)-|(-2.1,-0.15);
  \draw[-o] (-2.5,0.3)|-(-4,0.5)--(-4,0.1);
  \draw[o-] (-4,-0.1)--(-4,-0.5)-|(-2.5,-0.3);
  \node[left] at (-4,0){\small $U_\mathrm{H}\sim$};
  \draw[thick,red,decoration={aspect=0.5, segment length=0.85mm,
    amplitude=1.2mm,coil},decorate](-2.5,0.3)--(-2.5,-0.3)
  node[left,midway,inner sep=5]{\ding{172}};
  \node[]() at (7.7,1.5){\ding{176}};

  \draw[very thick] (-1,-0.7) -- (-1,-0.1);
  \draw[very thick] (-1,0.1)--(-1,0.8) node[midway,right]{\ding{174}};

  \node [contact] (contact 1) at (-4,-0.5) {};
  \node [contact] (contact 2) at (-1,-0.7) {};
  \node [contact] (contact 5) at (-1,-2) {};
  \node [contact] (contact 3) at (-2.5,-0.7) {};
  \node [contact] (contact 4) at (-4,-1.1) {};
  \node[ground,rotate=-90](gndA) at (-1,-2.5){};
  \draw (contact 2)--(gndA);
  \draw (contact 5) to [battery={info={\small
      $U_\mathrm{A}#1$}}] (-4,-2)--(contact 1);
  \draw (contact 4) to [battery={info'={\small
      $U_\mathrm{W}$}}] (-3,-1.1)--(-2.5,-1.1)--(contact 3);
  \draw[very thick,blue,->,dotted] (-2.3,0)--(-1.5,0);
  \draw[very thick,blue,->,dotted] (-1.5,0)--(0,0);

  \draw[very thick] (2,0.5) -- (0,0.5) node[above right]{\ding{175}};
  \draw[very thick] (0,-0.5) -- (2,-0.5);
  \draw[] (1,-0.5)|-(contact 5);
  \draw[-o] (1,0.5)--(1,1) node[anchor=west]{#2};
}

\begin{document}
\begin{tikzpicture}[>=latex,scale=1,circuit ee IEC]
  \def\myUB{200}
  \def\myUC{60}
  \def\myd{1} % cm
  \def\myl{2} % cm
  \tikzmath{
    \mya = \myUC/4/\myd/\myUB;
    \myyl = \mya*\myl*\myl;
    \mym = \myUC/2/\myd/\myUB*\myl;
  }
%  \fill[white] (-4,-3) rectangle (9,3);

  \egun{=\myUB\,\mathrm{V}}{\small $U_C=\myUC\,\mathrm{V}$}

  \draw[<->] (0,-0.75)--(2,-0.75) node[midway,fill=white,inner
  sep=1]{$l$};
  \draw[<->] (1.3,0.5) -- (1.3,-0.5) node[midway,fill=white,inner
  sep=2]{$d$};
  \draw[<->] (2,0) -- (8,0) node[midway,fill=white]{$L$};
  \draw[dotted] (2,\myyl) -- (8,\myyl);

  \draw[<->] (8,\myyl)--+(0,\mym*6) node[midway,right]{$y_L$};
  \tikzmath{ \mysgn = \myyl/sqrt(\myyl*\myyl); }
  \draw[->] (8,-0.5*\mysgn) -- (8,0);
  \node[right]() at (8,\myyl/2){$y_l$};
%  \draw[dotted,blue] (0,0)--(8,0);
  \draw[very thick,blue,dotted,smooth,domain=0:2,samples=20,->] plot function
  {\mya*x**2};
  \draw[very thick,blue,dotted,->] (2,\myyl)--+(6,\mym*6);
\end{tikzpicture}
\end{document}