% Präambel
\documentclass[a4paper,12pt,parskip]{scrartcl}
\usepackage[ngerman]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\pagestyle{empty}
\usepackage[output-decimal-marker={,}]{siunitx}
\usepackage[siunitx,european,nooldvoltagedirection]{circuitikz} 

% document-Umgebung
\begin{document}   \begin{circuitikz}
\draw (0,0) node[npn](npn) {} 
   (npn.base) node[below] {B}
   (npn.collector) node[below right] {C} 
   (npn.emitter) node[above right] {E} ;
\draw (-4,0) to[short,o-] (-4,0) to[resistor,l^=$R_2$] (npn.base);
\draw (-4,1.5) to[short,o-] (-3.5,1.5) to[resistor,l^=$R_1$]
   (-2,1.5) to[empty led,] (0,1.5) to (npn.collector); 
\node[ground] at (npn.E) {};
\node[left] at (-4.2,1.5) {\SI{3,3}{\volt}} ;
\node[left] at (-4.2,0) {GPIO\,23} ;
\node[left] at (-0.3,-1.25) {GND} ;
\end{circuitikz}
\end{document}