logic gates circuit diagram , simple question

Question

I am new to tikz and am trying to reproduce the following simple diagram

I did the following,

\usepackage{circuitikz}
\begin{tikzpicture}
    \node (p) at (0,0) {$p$};
    \node (p2) at (0,0.5) {$p$};
    \node (p3) at (2.5,0.25) {$\overline{p}$};
    \node[american nand port, draw] at ($(p) + (2.0,0.25)$) (NAND1) {};
            
    \draw (p) -- (NAND1.in 2);
    \draw (p2) -- (NAND1.in 1);
    \draw (NAND1.out 1) -- (p3);
\end{tikzpicture}

I get the following result

The lines from the p's are not straight, I could tweak the nodes from like 0.52, -0.01 but that seems like a wrong approach. How can I make these elements with discrete distances ?

Answer 1

Basically, you can't. Sizes of the circuitikz components are built based on a standard size; you can tweak it to have, for example, 2-input ports at a given distance (if you do not rescale the TikZ coordinates), see here: Needing a dipchip of CircuiTikz with exact pin distance --- you will need to put them at 0.5 cm to have your example with straight lines.

BUT the best solution is using coordinates that are relative to the anchors:

\documentclass[border=10pt]{standalone}
\usepackage[siunitx, RPvoltages]{circuitikz}
\begin{document}
\begin{tikzpicture}
    \node[american nand port, draw] at (0,0) (NAND1) {};

    \draw (NAND1.in 2) -- ++(-0.5,0) coordinate(p);
    \draw (NAND1.in 1) -- ++(-0.5,0) coordinate(p2);
    \draw (NAND1.out) coordinate (p3);

    \node[left] at (p) {$p$};
    \node[left] at (p2) {$p$};
    \node[right] at (p3) {$\overline{p}$};
\end{tikzpicture}
\end{document}

Are you sure you do not want standard IEEE ports? If you add \ctikzset{logic ports=ieee} you have the option to change pin lengths, see Simple Logic gates with circuitikz - increase I/O line length

As an example, let's see how to make your example work with absolute lengths. If you look at the manual (pag. 119) you discover that the default height of the ports is 0.8 basic units. So if I make the basic unit 1.25cm, the port will be 1 cm tall, and the connections 0.5 cm apart.

\documentclass[border=10pt]{standalone}
\usepackage[siunitx, RPvoltages]{circuitikz}
\ctikzset{bipoles/length=1.25cm}
\begin{document}
\begin{tikzpicture}
    \node (p) at (0,0) {$p$};
    \node (p2) at (0,0.5) {$p$};
    \node (p3) at (2.5,0.25) {$\overline{p}$};
    \node[american nand port, draw] at ($(p) + (2.0,0.25)$) (NAND1) {};
            
    \draw (p) -- (NAND1.in 2);
    \draw (p2) -- (NAND1.in 1);
    \draw (NAND1.out) -- (p3);
\end{tikzpicture}
\end{document}

Still, this solution is not optimal. Rounding errors are prone to create problems (especially to the antialiasing routines of PDF viewers...)