% Author: Dr. Matthias Jung, DL9MJ
% Year: 2021
% 3-TD121
\begin{circuitikz}[american]
    
    \draw(0,5) to [short, -*] ++(3,0) coordinate(C1)
    to [european resistor, l={$R_3$},-*] ++(0,-2.5) coordinate(C2)
    to [european resistor, l={$R_4$},-*] ++(0,-2.5) coordinate(C5)
    to [short] ++(-3,0) coordinate(C3);
    
    \draw(0,5) to [european resistor, l_={$R_1$},-*] ++(0,-2.5) coordinate(C4)
    to [european resistor, l_={$R_2$}] ++(0,-2.5);
    
    \draw(C4)  to [short,-o] ++(1,0)
    to [short,-o] ++ (1,0)
    to (C2);
    
    \draw(C5) -- ++(1.5,0) to node[ocirc, label=right:b]{} ++(0,0);
    \draw(C1) -- ++(1.5,0) to node[ocirc, label=right:a]{} ++(0,0);
    
\end{circuitikz}