% Author: Dr. Matthias Jung, DL9MJ
% Year: 2020
% TK203-Q1
\begin{circuitikz}
    \draw[ultra thick] (0,0) -- ++(11,0);
    \draw[fill=gray!50, ultra thick] (1,-1) rectangle ( 2,1);
    \draw[fill=gray!50, ultra thick] (3,-1) rectangle ( 6,1);
    \draw[fill=gray!50, ultra thick] (7,-1) rectangle ( 8,1);
    \draw[fill=gray!50, ultra thick] (9,-1) rectangle (10,1);
\end{circuitikz}