Analog Computer Symbols

Question

I am trying to draw analog computer symbols (I will put a picture of the entire list later). Right now, I am trying to draw a symbol of an analog integrator. Here's what I have right now in code:

\documentclass[12pt]{article}

\usepackage{amssymb, graphicx}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{float}
\usepackage{enumitem}
\usepackage{amsfonts,bm}
\usepackage{diagbox}
\usepackage[makeroom]{cancel}
\usepackage{pgfplots}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows}
\usepackage{verbatim}
\usepackage[american,siunitx]{circuitikz}
\usepackage[export]{adjustbox}
\usepackage{mathtools}
\DeclarePairedDelimiter\ceil{\lceil}{\rceil}
\DeclarePairedDelimiter\floor{\lfloor}{\rfloor}
\usepackage{units}
\usepackage{relsize}
\usepackage[margin=1in]{geometry}

\begin{document}

    \tikzstyle{block} = [draw, rectangle, 
    minimum height=3em, minimum width=3em]
    \tikzstyle{sum} = [draw, circle, node distance=1cm]
    \tikzstyle{input} = [coordinate]
    \tikzstyle{output} = [coordinate]
    \tikzstyle{pinstyle} = [pin edge={to-,thin,black}]
    \begin{figure}[H]
            \centering
            % The block diagram code is probably more verbose than necessary
            \begin{tikzpicture}[auto, node distance=2cm,>=latex']
                \node[regular polygon,regular polygon sides=3, draw, shape border rotate=-90, scale = 2.5, name = integrator]{};
                \draw (integrator.corner 2) -- ++ (-0.5, 0) |- (integrator.corner 3);
            \end{tikzpicture}
            \caption{Control block diagram.}
        \end{figure}

\end{document}

Here's what I have right now:

Right now, the lines aren't properly connecting to the vertices as I want. Is there a way to properly connect them such that there isn't any space in between the lines and the corners?

Edit: here is a list of analog computer symbols so one can understand what I am trying to do for the integrator (and the derivative):

Another example (which is seeemingly done on LaTeX):

Update: here is my example circuit that I want to draw on LaTeX:

Corresponding equation is here:

Can someone show me how to generalize the number of inputs to the summer and integrator with detailed explanation on the syntax? I tried to follow the code, but the syntax is super gnarly and very user unfriendly.

Answer 1

I think all of that can be achieved with circuitikz. Here are two examples. BTW, \tikzstyle is deprecated.

\documentclass{article}
\usepackage{amsmath}
\usepackage[american,siunitx]{circuitikz}
\begin{document}
\begin{circuitikz}
 \draw (0,0) to[amp,t=$\boldsymbol{K}$] ++(3,0); 
 \ctikzset{amplifiers/minus={$k_1$},amplifiers/plus={$k_2$}}
 \draw (0,-1.5) -- ++(1,0) node[op amp, anchor=-](sum){};
 \tikzset{cop amp/.style 2 args={op amp,
 /utils/exec=\ctikzset{amplifiers/minus={},amplifiers/plus={}},
 append after command={%
 pic{rect={#1}{#2}}
 }},
 pics/rect/.style 2 args={code={\let\mytikzlastnode\tikzlastnode
 \draw[thick,fill=white] (\tikzlastnode.bin up|-\tikzlastnode.north) 
 -- ++({-1.1*max(width("#1"),width("#2"))-8pt},0) |- (\tikzlastnode.bin up|-\tikzlastnode.south)
 -- cycle;
 \path (\mytikzlastnode.bin up) node[left=0pt,font=\boldmath] {#1}
  (\mytikzlastnode.bin down) node[left=0pt,font=\boldmath] {#2};
 }}}
 \draw (1,-4)  node[cop amp={$k_1$}{$k_2$}, anchor=-](sum){};
\end{circuitikz}
\end{document}

Let me try to explain what

\tikzset{cop amp/.style 2 args={op amp,
 /utils/exec=\ctikzset{amplifiers/minus={},amplifiers/plus={}},
 append after command={%
 pic{rect={#1}{#2}}
 }},
 pics/rect/.style 2 args={code={\let\mytikzlastnode\tikzlastnode
 \draw[thick,fill=white] (\tikzlastnode.bin up|-\tikzlastnode.north) 
 -- ++({-1.1*max(width("#1"),width("#2"))-8pt},0) |- (\tikzlastnode.bin up|-\tikzlastnode.south)
 -- cycle;
 \path (\mytikzlastnode.bin up) node[left=0pt,font=\boldmath] {#1}
  (\mytikzlastnode.bin down) node[left=0pt,font=\boldmath] {#2};
 }}}

does. It defines a modified op amp node. It uses this node, hence the op amp key. Then it it removes the + and - with /utils/exec=\ctikzset{amplifiers/minus={},amplifiers/plus={}}. (One may argue that using /utils/exec is not always optimal. I agree with Henri on that. However, TikZ even uses it internally, i.e. it can be found in tikz.code.tex. I think here it is fine.) The main ingredient is the append after command key, which issues a pic that adds the rectangle. The rectangle gets attached to the node, the name of which is stored in \tikzlastnode. Since we are adding other nodes, it gets stored on \mytikzlastnode. By measuring the size of the arguments we can make sure that the rectangle is large enough. One could also use fit here.

Below is an edit by Eduardo Alves da Silva, thanks a lot!

EDIT : Regarding on how to use, for example, to make the image you've provided:

\documentclass[border = 5pt]{standalone}
\usepackage[RPvoltages]{circuitikz}
\usepackage{calc}
\usepackage{tikz}
\tikzset{cop amp/.style 2 args={op amp,
    /utils/exec=\ctikzset{amplifiers/minus={},amplifiers/plus={}},
    append after command={%
        pic{rect={#1}{#2}}
}},
pics/rect/.style 2 args={code={\let\mytikzlastnode\tikzlastnode
        \draw[thick,fill=white] (\tikzlastnode.bin up|-\tikzlastnode.north) 
        -- ++({-1.1*max(width("#1"),width("#2"))-8pt},0) |- 
(\tikzlastnode.bin up|-\tikzlastnode.south)
        -- cycle;
        \path (\mytikzlastnode.bin up) node[left=0pt,font=\boldmath] {#1}
        (\mytikzlastnode.bin down) node[left=0pt,font=\boldmath] {#2};
}}}
\begin{document}
\begin{circuitikz} [american voltages]
    \node[draw,minimum size,fill=white] (-1) {-1};
    \draw (-1.east) to[short,-] ++(1,0)
    node[draw, circle,anchor=west] (g) {g};
    \draw (g.east) to[short] ++(0.5,0) node[cop amp={}{}, anchor=-](int1){};
    \draw (int1.out) to[short] ++(1,0) coordinate (aux) to[short] ++(1,0) node[cop amp={}{}, anchor=west] (int2) {};
    \draw (aux) to[short,*-] ++(0,-2) coordinate (aux2);
    \draw[-] (aux2) -- ++(-2,0) node[draw,circle,anchor=east] (dm) {$d/m$};
    \draw[-] (dm) --++(-1.5,0) coordinate (aux2);
    \draw[-] (aux2) |- (int1.+);
    \draw (aux) node[above] () {$-\dot{y}$};
    \draw (int2.out) to[short] ++(0.5,0) node[above] () {$y$};
    \draw (int2.out) to[short, *-] ++(0,-3.5) to[short] ++(-1,0) node[buffer,xscale=-1,anchor=in] (buffer) {};
    \draw (buffer.out) to[short] ++(-0.5,0) node[above] () {$-y$};
    \draw (buffer.out) to[short] ++(-1,0) node[draw,circle,anchor=east] (cm) {$c/m$};
    \draw (cm.west) to[short] ++(-3.5,0) coordinate (aux) to[short] (aux |- int1.west)
    to[short] (int1.west);
\end{circuitikz}
\end{document}