In a circuitikz diagram, how can I avoid the labels overlapping each other, add +/-, and add custom elements?

Question

I cut this out so that there is no confusion.

I have this picture:

And I've managed to draw this:

The code is as follows:

\begin{figure}
\begin{circuitikz}[european]
\draw[o-] (0,2.2) to (0,4);
\draw (0,4) -- (1,4);
\draw (1,4) to[R,l_=\SI{1}{\kilo\ohm},-*]  (1,2) to[R,l_=\SI{500}{\ohm},-*] (1,0)
        -- (0,0);
\draw[-o] (0,0) -- (0,1.5);
\draw (1,2) -- (3,2);
\draw (3,2) -- (4,2) node[component]{A} -- (5,2);
\draw (3,0) -- (3,1) node[component]{V} -- (3,2);
\draw
 (6,2.27) node[njfet]{}
    node[anchor=east] {G}
    node[anchor=north] {D}
    node[anchor=south] {S};
\draw (6,0) -- (6,2);
\draw (6,3) -- (6,4);
\draw (1,0) -- (8,0);
\draw (2,0) to[C,l^=\SI{4.7}{\nano\farad},*-*] (2,2);
\draw (7,0) -- (7,2) node[component]{V} -- (7,4);
\draw (6,4) -- (6.5,4) node[component]{A} -- (8,4);
\draw[o-] (8,2.2) to (8,4);
\draw[-o] (8,0) to (8,1.5);
\end{circuitikz}
\end{figure}

I guess you can see where is the problem:

1. how to add + and - on the nodes?
2. how to make writings not overlap each other?
3. when I tried to make the code for the jfet like the one from the manual I got errors about (njfet. G) stuff...

So any advice on how to solve this?

EDIT: Oh and can I somehow modify the elements? Because, for instance, npn BJT has arrow pointing out of emmiter and I need it to point it in...

Answer 1

To avoid the overlap, draw the component, then draw and rotate text next to the component.

To change arrow direction change the element: njfet (out) to pjfet (in) or npn (out) to pnp (in).

It may also help to 'stretch' or 'compress' parts of the circuit. Try this re-worked sample to see if it works for you.

\documentclass{article}
\usepackage[european]{circuitikz}
\usepackage{siunitx}

\begin{document}
%----Fet circuit
\begin{circuitikz}[european]
\draw (3,3.5) node[above] {FET circuit}; 
\draw
(0,2.2) node[left] {$+$} to[short,o-] (0,4);
\draw (0,4) -- (1,4);
%\draw (1,4) to[R,l^=\SI{1}{\kilo\ohm},-*]  (1,2) 
%   to[R,l^=\SI{500}{\ohm},-*] (1,0) -- (0,0);
\draw (1,4) to[R,-*]  (1,2) 
    to[R,-*] (1,0) -- (0,0);

% place labels for resistors
\draw (0.5,1.5) node[rotate=90,left]{500 $\Omega$};
\draw (0.5,3.2) node[rotate=90,left]{1 $\Omega$};

\draw (0,1.5) node[left] {$-$} to[short,o-] (0,0);
\draw (1,2) -- (3.6,2);
\draw (3.6,2) to[ammeter] (5,2);
\draw (3.5,0) to[voltmeter] (3.5,2);
\draw  
    (6,2.27) node[njfet] (fet) {} 
    (fet.G) node[anchor=south]  {G}
    (fet.D) node[anchor=north east] {D}
    (fet.S) node[anchor=south east] {S};
\draw (6,0) -- (fet.S);
\draw (fet.D) -- (6,4);
\draw (1,0) -- (9,0);
%\draw (2,0) to[C,l_=\SI{4.7}{\nano\farad},*-*] (2,2);
\draw (2,0.6) node[right]{4.7 nF};
\draw (2,0) to[C,*-*] (2,2);
\draw (8,0) to[voltmeter] (8,4);
\draw (6,4) to[ammeter] (8,4) -- (9,4);
\draw (9,2.2) to[short,o-]  (9,4);
\draw (9,0)   to[short,-o]  (9,1.5);
\end{circuitikz}
\end{document}

Answer 2

1. for + and - : add a node at the appropriate place. For example, at the beginning of your code:

   \draw (0,2.2) node[left] {$+$} to[short,o-] to (0,4);
   

   (note that I also changed the way the circle is created)

2. I couldn't find anything specific about it in the documentation. What I suggest doing is moving some of the commponents a little (the capacitor and the voltmeter to the right for example) and using a smaller font. Another way is to add explicit nodes. You then have complete control for the placement.

3. For the labels on the jfet : all of your nodes are placed with respect to the point (6,2.27). You want the labels to be placed with respect to the component. For this, give the component a name and place the label node with respect to the ins and outs (G, D and S) :

   \draw  (6,2.27) node[njfet] (myname){} 
      (myname.G) node[anchor=east] {G}
      (myname.D) node[anchor=north] {D}
      (myname.S) node[anchor=south] {S};