\documentclass[tikz,border=10pt]{standalone}
\usepackage{circuitikz}
\begin{document}
\begin{tikzpicture}
\draw (-2,0) to[european resistor=$R$] (0,0);
\draw (2,0) to[D-,] (2,-2);
\draw(2,-2)--(-2,-2)--(-2,0);
\draw(0,0) to [qiprobe] (2,0);
\fill[white](-2.2,-1.1)--(-2.2,-0.9)--(-1.8,-0.9)--(-1.8,-1.1);
\draw[very thick](-1.8,-1.1)--(-2.2,-1.1);
\draw(-2.4,-0.9)--(-1.6,-0.9);
\draw[->](-2.15,-1.4)--(-1.85,-0.6);
\draw(-2.6,-1)node{$E$};
\draw(2,-0.4)--(3,-0.4);
\draw(2,-1.6)--(3,-1.6);
\draw(3,-0.4) to [qvprobe] (3,-1.6);
\fill[ball color=black](2,-0.4)circle(0.075);
\fill[ball color=black](2,-1.6)circle(0.075);
\draw(2,-2) to node[eground2]{} (2,-2);
\end{tikzpicture}
\end{document}
\documentclass[tikz,border=10pt]{standalone}
\usepackage{luatexja}
\usepackage{circuitikz}
\begin{document}
\begin{tikzpicture}
\draw[very thick](0,1)--(2.5,1);
\draw(0.5,1)--(0.5,-0.4);
\draw(0.5,-2)--(0.5,-0.6);
\draw(0,-0.4)--(1,-0.4);
\draw(0.2,-0.6)--(0.8,-0.6);
\draw[very thick](1.5,-1)--(3.5,-1);
\draw (2,1) to[european resistor=$R$] (2,-1);
\draw (2.75,-1) to[D-,l=] (2.75,-2);
\draw[very thick](0,-2)--(3.5,-2);
\draw(1.5,-3)node{図8: 図7の電位図};
\draw[-{>[scale=1.75]}](-0.5,-2)--(-0.5,1);
\draw(-0.75,-0.5)node{$E$};
\draw[-{>[scale=1.75]}](4,-2)--(4,-1);
\draw(4.25,-1.5)node{$V$};
\end{tikzpicture}
\end{document}
LEDの直流電圧特性測定回路
\documentclass[tikz,border=10pt]{standalone}
\usepackage{circuitikz}
\begin{document}
\begin{tikzpicture}
\fill(2,-1)[top color=white, bottom color=cyan!5!blue!5!white]circle(0.5);
\fill(2,-1.1)[top color=white, bottom color=cyan!15!blue!15!white]circle(0.25);
\fill(2,-1.25)[top color=white, bottom color=cyan!30!blue!30!white]circle(0.1);
\draw[densely dotted](2,0)--(4.5,0);
\draw[densely dotted](2,-2)--(4.5,-2);
\draw[{<[scale=1.5]}-{>[scale=1.5]}](4.25,0)--(4.25,-2);
\draw(4.6,-1)node{$V_{\textmd{F}}$};
\draw[-{[scale=10]>},-latex,](1.4,-0.5)--(1.4,-1.5)node[left]{$I_{\textmd{F}}$};
\draw (-2,0) to[european resistor=$R$] (0,0);
\draw(2,0) to[D-,] (2,-2);
\draw(2,-2)--(-2,-2)--(-2,0);
\draw(0,0) to [qiprobe] (2,0);
\fill[white](-2.2,-1.1)--(-2.2,-0.9)--(-1.8,-0.9)--(-1.8,-1.1);
\draw[very thick](-1.8,-1.1)--(-2.2,-1.1);
\draw(-2.4,-0.9)--(-1.6,-0.9);
\draw[->](-2.15,-1.4)--(-1.85,-0.6);
\draw(-2.6,-1)node{$E$};
\draw(2,-0.4)--(3,-0.4);
\draw(2,-1.6)--(3,-1.6);
\draw(3,-0.4) to [qvprobe] (3,-1.6);
\fill[ball color=black](2,-0.4)circle(0.075);
\fill[ball color=black](2,-1.6)circle(0.075);
\draw(2,-2) to node[eground2]{} (2,-2);\end{tikzpicture}
\end{document}