Circle Around Transistor

[myzinsky]

I did a workaround like presented on Stack-Overflow:

\documentclass[convert = false, border=10pt,]{standalone}
\usepackage[siunitx, straightvoltages]{circuitikz}

\def\CalcC#1{%
\coordinate (base) at (#1.B);
\coordinate (collector) at (#1.C);
\coordinate (emitter) at (#1.E);
\draw (barycentric cs:base=0.5,collector=0.5,emitter=0.5) circle [radius=14pt];
}

\begin{document}
\begin{circuitikz}[european]
    %\tikzstyle{help lines}=[blue!50];
    %\draw[style=help lines] (0,0) grid (5,5);
	\draw (4,0) node[ground](gnd1){};
	\draw (5,0) node[ocirc](Agnd){};
	\draw (0,0) node[ocirc](Egnd){};
	\draw (5,5) node[ocirc, label={$V_{DD}=+12\,\mbox{V}$}](vdd1){};
	\draw (5,3) node[ocirc, label=A](A){};
	\draw (0,2) node[ocirc, label=E](E){};
	\draw (4,2) node[npn](npn1){}; 
	\CalcC{npn1};
	% Lines:
	\draw(Egnd) -- (gnd1);
	\draw(Agnd) -- (gnd1);
	\draw(1,5)  -- (vdd1);
	\draw (npn1.E) to [short,-*] (gnd1.north);
	\draw (npn1.C) -- ( 4,3) -- (A.west);
	\draw (npn1.C) -- ( 4,3) to [R,*-*] (4,5); 
	\draw (npn1.B) -- ( 2,2) to [R,*-*] (2,5); 
	\draw (npn1.B) -- ( 2,2) to [R,*-*] (2,0); 
	\draw (npn1.B) -- ( 2,2) to [C,*- ] (E.east); 
	% Volatages:
	\draw (A.south) to [open, v^=$U_a$] (Agnd.north); 
	\draw (E.south) to [open, v=$U_e$] (Egnd.north); 
\end{circuitikz}
\end{document}

But of course it would be great to have this also natively.

[Rmano]

This is a lot of work and, for what I know, circles around transistors is a deprecated style since at least the '90.
I would consider a PR, if it's optional and well integrated, but personally I don't like them and I don't think it's worth the effort.

[myzinsky]

Yes fair enough. I would do a a PR but I dont understand how tikz works under the hood. I'm just a LaTeX user :-)

[Rmano]

I will let this open, let's see if someone steps in. Anyway, the macro that was suggested in the link above is quite nice to use...
My other problem is that --- what do you do with the other transisors? FET, MOS, etc... ? Should all of them have optional circles?

[dl1chb]

[EDIT] --> wrong document: <--- This is from IEEE-91-1984 1. --> I will look for the valid one! <---[/EDIT]

As far as I know, this circle represents a transistor in a housing, not one in an integrated circuit. Maybe this is obsolete, maybe still valid. Then for a MOSFET the same rule should be applied.

[EDIT]: What is the consecutively following document of IEEE-91-1984? What does ist say about this? <-- this should also not be valid and is included in 1.[/EDIT]

[Rmano]

I am working on it...

[Rmano]

Please check and comment the PR #470