# How to do small Bar for voltage input on opAmp

How can I do those small bars at the end of a wire?

Specifically at the end of (opamp.up) and (opamp.down)

\begin{circuitikz}[american inductors]
\draw
(7,2.5) node[op amp] (opamp){}
(opamp.down) ++ (0,-.5) node[below] {$-Va$}
-- (opamp.down)
;
\end{circuitikz}


I tried to use the perpendicular sign -| but obviously it's not meant for that.

So, is there a command for that (perpendicular) bar ?

Based on this excellent answer from Peter Gill, here are two new styles (named opampdownlbl and opampuplbl) which handle the placement and draw the horizontal lines at the top and bottom of the node.

\documentclass{article}

\usepackage{circuitikz}

\tikzset{opampdownlbl/.style={
below,
draw=none,
append after command={
(\tikzlastnode.north) edge ([shift={(-5pt,0pt)}]\tikzlastnode.north) edge ([shift={(+5pt,0pt)}]\tikzlastnode.north)
}},
opampuplbl/.style={
above,
draw=none,
append after command={
(\tikzlastnode.south) edge ([shift={(-5pt,0pt)}]\tikzlastnode.south) edge ([shift={(+5pt,0pt)}]\tikzlastnode.south)
}}}
\begin{document}
\begin{circuitikz}[american inductors]
\draw (7,2.5) node[op amp] (opamp){}
(opamp.down) ++ (0,-.5) node[opampdownlbl] {$-Va$} -- (opamp.down)
(opamp.up) ++ (0,.5) node[opampuplbl] {$+Va$} -- (opamp.up);
\end{circuitikz}
\end{document}