% Author: Dr. Matthias Jung, DL9MJ
% Year: 2022
\begin{circuitikz}
    \draw (0.8, 0) -- ++(4.6,0.0) node[inputarrow]{} node[right]{$t$};
    \draw (1.0,-1) -- ++(0.0,2.5) node[inputarrow, rotate=90]{} node[above]{$U$};
    \draw[ultra thick]
        (1,0) -- ++(0, 1) -- ++(2, 0) 
              -- ++(0,-2) -- ++(2, 0) -- ++(0,1);
\end{circuitikz}