% Author: Prof. Dr. Matthias Jung
% Year: 2023
\begin{circuitikz}[european]
	\ctikzset{
	    resistors/scale=\getDarcImageFactor,
	    capacitors/scale=\getDarcImageFactor,
	    inductors/scale=\getDarcImageFactor,
	    diodes/scale=\getDarcImageFactor,
	    transistors/scale=\getDarcImageFactor
	}
    \draw(0,0) coordinate(u0)
        to [short, -*] ++(2,0) coordinate(u1)
        to [short, -*] ++(2,0) coordinate(u2)
        to [short, -*] ++(2,0) coordinate(u3)
        to [short, -*] ++(2,0) coordinate(u4)
        to [short, -o] ++(4,0) coordinate(u6)
        node[anchor=north](){--};
    \draw(0,0)
        to [american inductor, ] ++(0,4) coordinate(o0)
        to [short, -*] ++(2,0) coordinate(o1)
        to [short, -*] ++(2,0) coordinate(o2)
        to [short, -*] ++(2,0) coordinate(o3)
        to [C, -*] ++(2,0) coordinate(o4)
        to [short    ] ++(1,0) 
        node [npn, tr circle, anchor=B](T){};
    
    % Füllung
    \draw (u1) to [variable capacitor, tunable end arrow={Triangle}] (o1);
    \draw (u2) to [variable capacitor, tunable end arrow={Bar}]      (o2);
    \draw (o3)
        to [C, l_=$C_1$] ++(0,-2) coordinate(m3)
        to [C, l_=$C_2$, *-] (u3);
    \draw(o4) 
        to [short] (o4|-m3)
        to [R] (u4);
    \draw(T.E)
        to [short,-*] (T.E|-m3) coordinate(m5)
        to [R, -*] (m5|-u4)
        node[rground](){};
    \draw(m3)
        to [short] (m5)
        to [C, -o] (m5-|u6);
    \draw(o4)
        to [R, -*] ++(0,3) coordinate(g4)
        to [short, -*] (g4-|T.C) coordinate(g5)
        to [short] (T.C);
    \draw(g5)
        to [R, -o] (g5-|u6)
        node[anchor=south](){+};
    \draw(g4) 
        to [short, -*] ++(-2,0) coordinate(g3)
        to [short, -*] ++(-2,0) coordinate(g2)
        to [short    ] ++(-2,0) coordinate(g1)
        to [C, name={myC}] ++(0,-2)
        to [short, -*] ++(+2,0) coordinate(i2)
        node[rground](){}
        to [short    ] ++(+2,0) coordinate(i3)
        to [stroke Zener diode] (g3);
    \draw(g2)
        to [C] (i2);

    \draw (myC.south west) node[anchor=south]{$+$};
\end{circuitikz}