Example: Colpitts oscillator, with npn transistor

% Title: Colpitts oscillator, with npn transistor
% Author: Ramón Jaramillo
\documentclass[tikz, border=10pt, 12pt]{standalone}% adequate for simple figures
\usepackage[siunitx]{circuitikz} % Loading circuitikz with siunitx option
\begin{document}
\begin{circuitikz}
	\draw
	% Drawing a npn transistor
	(0,0) node[npn](npn1){} 
	% Making connections from transistor using relative coordinates
	(npn1.E) node[right=7mm, above=5mm]{2N2222} % Labelling the transistor
	(npn1.B) -- ++(-1,0) to [R,l_=10<\kilo\ohm>,*-*] ++(0,-3)  
	(npn1.B) -- ++(-3,0) to [C,l_=100<\nano\farad>] ++(0,-3) node(gnd1){}
	(npn1.E) to [R,l_=10<\kilo\ohm>,*-*] (0,-3)
	(npn1.E) -- ++(2,0) to [C,l=10<\pico\farad>,*-*] (2,-3)
	(npn1.B) -- ++(-1,0) to [R,l_=10<\kilo\ohm>,*-] ++(0,3) node(con1){}
	(npn1.C) to [L,l_=150<\micro\henry>,*-] (0,3) 
	(npn1.C) -- ++(2,0) to [C,l=10<\pico\farad>,*-*] ++(0,-1.5)
	% Drawing shorts and ground connection
	(-1,3)to[short,*-o] (-1,4) node[right]{$V_{DD}=6 VDC$} % Power supply
	% Output sinusoidal waveform at approximately 50 MHz
	(npn1.C) -- ++(4,0) to [short,-o]
	  ++(0,0) node[right]{$V_o (\approx \SI{50}{\MHz})$}
	(0,-3) node[ground]{}% Define this node as ground
	(gnd1) ++(0,0) to[short,-o] ++(7.85,0)
        (con1)to[short] ++(1.85,0)
	;
\end{circuitikz}
\end{document}