# Circuitikz – Straight voltage arrows with fixed length

In the example circuit there are five voltage arrows. Four of these have different lengths.

How can I draw all voltage arrows with the same and fixed (user defined) length? Thanks in advance for your support.

\documentclass[a4paper,10pt]{scrartcl}
\usepackage[european,straightvoltages]{circuitikz}
\ctikzset{bipoles/thickness=1}

\begin{document}

\begin{circuitikz}[line width = 0.35mm,voltage shift = 0.5]

\draw (0,0)
to[vsource, v_<=$U_0$] (0,4)
to[R,v>=$U_1$] ++(5,0);

\draw (5,4)
to[R,v>=$U_2$] ++(0,-4);

\draw (5,4)
to[short] ++({2.5},0)
to[R,v>=$U_3$] ++(0,-2)
to[R,v>=$U_4$] ++(0,-2)
to[short] (0,0);

\end{circuitikz}
\end{document}

As said by @Zarko (BTW, thanks!) the length and position of the arrow depends on the branch where they are, and not on the size of the component. This was a design decision from the dawn of times (for circuitikz), well before I started to co-maintain it, so it's basically set in stone.

I can think about a possible flag to change this (as soon as I have a bit of time), but notice that there are a lot of "bike-shedding" requests for this things... a lot of people have different tastes (and the right to have them!)

So I added lately the possibility of "advanced voltages, currents and flows" (manual around page 155), and you can easily obtain what you want although the syntax is not so nice (I am thinking about changing this too, but it's not easy to make a general thing).

\documentclass[a4paper,10pt]{scrartcl}
\usepackage[european,straightvoltages,EFvoltages]{circuitikz}
\ctikzset{bipoles/thickness=1}

\newcommand{\fixedvlen}[3][0.75cm]{% [semilength]{node}{label}
% get the center of the standard arrow
\coordinate (#2-Vcenter) at ($(#2-Vfrom)!0.5!(#2-Vto)$);
% draw an arrow of a fixed size around that center and on the same line
\draw[blue, -Triangle] ($(#2-Vcenter)!#1!(#2-Vfrom)$) -- ($(#2-Vcenter)!#1!(#2-Vto)$);
% position the label as it where if standard voltages were used
\node[blue, anchor=\ctikzgetanchor{#2}{Vlab}] at (#2-Vlab) {#3};
}

\begin{document}

\begin{circuitikz}[line width = 0.35mm,voltage shift = 0.5]

\draw (0,0)
% using name=... and v_< without arguments enables the labels and nodes
% for personalized voltages.
to[vsource, bipole/is voltage=false, v_<, name=u0] (0,4)
to[R,v>, name=u1] ++(5,0);

\draw (5,4)
to[R,v>, name=u2] ++(0,-4);

\draw (5,4)
to[short] ++({2.5},0)
to[R,v>,name=u3] ++(0,-2)
to[R,v>,name=u4] ++(0,-2)
to[short] (0,0);

\fixedvlen{u0}{$U_0$}
\fixedvlen{u1}{$U_1$}
\fixedvlen[1cm]{u2}{$U_2$} % longer, to show off
\fixedvlen{u3}{$U_3$}
\fixedvlen{u4}{$U_4$}

\end{circuitikz}
\end{document}

Notice that I added the bipole/is voltage=false flag to the generator to suppress the special treatment for it.

This technique is quite powerful --- you can really personalize voltages, currents and flows the way you feel better (in this case I colored them blue, just as an example; but the possibilities are limitless). Also, if you keep a coherent naming, you can simplify the thing a lot... for example, you can change the 5 final lines (losing the different U_2 length) with:

\foreach \ii in {0,...,4} {\fixedvlen{u\ii}{$U_\ii$}}

### update: I will add this example (and another one for voltage arrows with a length based on the component length) on the manual: https://github.com/circuitikz/circuitikz/pull/466

• Thank you very much! +1 Dec 11, 2020 at 19:37
• @Zarko you're welcome. Please do not delete your answer, it's very useful to show what's happening! Dec 11, 2020 at 19:38
• Don't worry I will not. By it I earn (so far) 30 point of reputation ;-). Dec 11, 2020 at 20:01
• Thank you very much! This will be very helpful. Now we need only to wait that this documentation adition will propagate to next package realise soon :-) Dec 12, 2020 at 13:12
• I am sorry for asking this off-topic question, but I have an old ciruitikz code that gives me this warning now: You did not specify one of the voltage directions:(circuitikz) oldvoltagedirection, nooldvoltagedirection, (circuitikz) RPvoltages or EFvoltages (circuitikz) Default directions may have changed, (circuitikz) please check the manual. . So, what should I do?
– Diaa
Dec 22, 2020 at 15:53

Apparently voltage arrows is not depends on resistor size but on distance between coordinates between which a resistor is draw. With other words, you need toprovide equal sized this distances:

\documentclass[margin=3mm]{standalone}
\usepackage[european, straightvoltages]{circuitikz}
\ctikzset{bipoles/thickness=1}

\begin{document}
\begin{circuitikz}[
line width = 0.8pt,
voltage shift = 0.5]
\draw (0,0)     to[vsource, v_<=$U_0$]  (0, 4) -- ++ (0.5,0)
to[R,v>=$U_1$]      ++  (2, 0) -- ++ (0.5,0) coordinate (aux)
-- ++  (0,-1)
to[R,v>=$U_2$]      ++  (0,-2) -- ++ (0 ,-1)
(aux)     to[short]           ++  (2, 0)
to[R,v>=$U_3$]      ++  (0,-2)
to[R,v>=$U_4$]      ++  (0,-2)
to[short] (0,0);
\end{circuitikz}
\end{document}

which gives:

This can be considered as mis features of the package. I hope that one of the authors of the package will soon see your question and suggest a better solution or ptovide some fix of package.

• @Franklin, instead saying "thanks" you can upvote answer. So far to get what you like, not exist another possibility. Dec 11, 2020 at 15:22
• @Zarko --- your analysis is correct, but this kind of behavior has been with circuitikz since forever. I can think about adding an option to have a fixed length or a component-size dependent length, but it's quite a bit of work so... don't hold your breath. It would be nice to have a feature request in the issues though, to track the thing. Dec 11, 2020 at 18:40
• @Franklin yes, sources are treated differently. You can override it as explained in the manual around page 148 with bipole/is voltage=false. Dec 11, 2020 at 18:45
• @Rmano, anyway, I will keep finger crossed :-). I follow circuitikz development from its start. Impressive works! Dec 11, 2020 at 18:52
• @Franklin about arrow tips: in circuitikz they are not arrow tips, see tex.stackexchange.com/a/549354/38080 --- they are shapes, and fixed ones. You can use the "advanced" mechanism for voltages, currents and flows but there is nothing you can do to change, for example, transistor's arrows. For the color, just add an argument to the macro. Dec 11, 2020 at 22:50

Based on the hints by @Rmano, here is a solution with individual length and color of the voltage arrows, and the correct CircuiTikZ arrow tip. If you want to have all arrows look the same, set all paramters to the same values, e. g. by using the \foreach loop.

\documentclass[border=1mm]{standalone}

\usepackage[european,straightvoltages,EFvoltages]{circuitikz}

% Set CircuiTikZ arrow dimensions
\makeatletter
\newdimen\ctikzAL\newdimen\ctikzAW
\pgfmathsetlength{\ctikzAL}{ 1.7 * \pgf@circ@Rlen / \ctikzvalof{current arrow scale} + 2*\pgflinewidth}
\pgfmathsetlength{\ctikzAW}{ 1.6 * \pgf@circ@Rlen / \ctikzvalof{current arrow scale} + 2*\pgflinewidth}
\makeatother

% #1 – Color, #2 – Length, #3 – Short name, #4 – Long name
\newcommand{\fxdvlen}[4][black]{
\coordinate (#3-Vcenter) at ($(#3-Vfrom)!0.5!(#3-Vto)$);
\draw[#1, -{Triangle[length=\the\ctikzAL, width=\the\ctikzAW]}] ($(#3-Vcenter)!#2!(#3-Vfrom)$) -- ($(#3-Vcenter)!#2!(#3-Vto)$);
\node[#1, anchor=\ctikzgetanchor{#3}{Vlab}] at (#3-Vlab) {#4};
}

\begin{document}

\begin{circuitikz}[line width = 0.35mm,voltage shift = 0.5]
\ctikzset{bipoles/thickness=1}

\draw (0,0)
% using name=... and v_< without arguments enables the labels and nodes for personalized voltages
to[vsource, bipole/is voltage=false, v_<, name=u0, i>=$I$] (0,3)
to[R,v>, name=u1] ++(3,0);

\draw (3,3)
to[R,v>, name=u2] ++(0,-3);

\draw (3,3)
to[short] ++(1.5,0)
to[R,v>,name=u3] ++(0,-1.5)
to[R,v>,name=u4] ++(0,-1.5)
to[short] (0,0);

%\foreach \ii in {0,...,4} {\fxdvlen[blue]{5mm}{u\ii}{$U_\ii$}}

Individual voltage arrows
\fxdvlen[red]{7mm}{u0}{$U_0$}
\fxdvlen[green]{6mm}{u1}{$U_1$}
\fxdvlen[blue]{5mm}{u2}{$U_2$}
\fxdvlen[brown]{4mm}{u3}{$U_3$}
\fxdvlen{3mm}{u4}{$U_4$}

\end{circuitikz}

\end{document}