how to draw a circle with black border with pstricks?

I would like to draw a circle with black bounder in that electric field. Can you help me?

\documentclass[margin=10pt]{standalone}
\usepackage{pstricks}
\usepackage{pst-electricfield}
\begin{document}
\begin{pspicture*}(-6,-6)(6,6)
\psframe*[linecolor=white!50](-6,-6)(6,6)
\psgrid[subgriddiv=0,gridcolor=gray,griddots=10]
\psElectricfield[Q={[-1 -2 2][1 2 2][-1 2 -2][1 -2 -2]},linecolor=red, radius=1.0]
%\psEquipotential[Q={[-1 -2 2][1 2 2][-1 2 -2][1 -2 -2]},linecolor=blue](-6.1,-6.1)(6.1,6.1)
%\psEquipotential[Q={[-1 -2 2][1 2 2][-1 2 -2][1 -2 -2]},linecolor=green,linewidth=2\pslinewidth,Vmax=0,Vmin=0](-6.1,-6.1)(6.1,6.1)
\end{pspicture*}
\end{document}


You may also need pst-electricfield.pro.

HERE'S THE FILES:

• I can't compile your code, and I'm note sure why. Can you compile it as it is? – Clément May 5 '16 at 16:36
• I compiled it with XeLatex. you also need the file .pro – ryuk May 5 '16 at 16:38
• Ok. Try to format properly your post, so that it can be copy-and-pasted easily. Have a look at tex.stackexchange.com/editing-help You can edit your own post. – Clément May 5 '16 at 16:46
• Where should be the circle? Which characteristics? – Bernard May 5 '16 at 17:12
• i draw with black every circle. – ryuk May 5 '16 at 17:32

\documentclass[margin=10pt]{standalone}