%texlabels := 1;
tracingstats:=1;
prologues:=2;
u:=10bp;
input mpcirc;
%texprolog := texprolog & "\def\ii{_{\rm{in}}}\def\oo{_{\rm{out}}}";
%    verbatimtex
%    \def\ii{_{\rm{in}}}\def\oo{_{\rm{out}}}
%	etex

%expandafter show get_vars_nest_(1);
%end

verbatimtex
\documentclass{minimal}
\begin{document}
etex


%%--------------------------------------------------
% five pins (left, 3 down, right), middle grounded?
%%--------------------------------------------------
defelem(bbv,
  z0=(-bb_lt/2,0); x1=x0=x2;
  z0=.5[z1,z2];
  y1-y2=y3-y4=bb_ht;  y1=y3;
  x3=x4=x0+bb_lt;
  pickup thickpen;
  draw z1--z2--z4--z3--cycle;
  addpin.a (.5[z1,z2])(lft);
  addpin.b (.5[z4,z3])(top);
  addpin.c (.25[z2,z4])(bot);
  addpin.d (.5[z2,z4])(bot);
  addpin.e (.75[z2,z4])(bot);
  addlab.lab (emptystr)(origin)(lft);
  addlab.val (btex\begin{tabular}{c}Network\\$N$\end{tabular}etex)(origin)(cntr);
);

u := 1cm;
w := 1.5u;


beginfig(1)
  prepare (current.X, bbv,rhombus, gnd2,gnd3,gnd4, current.o, V.i, gm,gnd1,
    gnd5,gnd6);

  gnd1 = origin;
  z1 = (0,1.5w);
  z2 = (4w,1.5w);
%  z2 = 0.5[z3, bbv.b];
  xpart z2 = xpart 0.5[gnd6, bbv.b];

  betw (bbv) 1,2;
  betw.u (V.i) gnd1,1;
  setlab.V.i.lab(btex$V_i$etex)(top)(top);

  abetw.d (current.X) bbv.c, gnd2;

  conn.v (gnd3, bbv.d) 0.3w;

  abetw.u (rhombus) gnd4,bbv.e;
  setlab.rhombus.lab (btex$K_2 V_i$etex)(bot)(bot);

  abetw.u (gm) gnd5,2;
  setlab.gm.lab (btex$K_1 I_X$etex)(bot)(bot);

  betw.d (current.o) gnd6,2;

  halign gnd1, gnd2, gnd4, gnd5, gnd6;
  edraw;

  label.ulft ("1", bbv.a);
  label.urt ("2", bbv.b);
  label.llft ("3", bbv.c);
  label.lrt ("4", bbv.e);

  junction 2;

endfig;

beginfig(2)
  prepare (current.X, bbv,rhombus, gnd2,gnd3,gnd4, I.i, ioc1,ioc2, gm,gnd1,
    gnd5,gnd6);

  ypart gnd1 = 0;
  z1 = (0,1.5w);
  z2 = (4w,1.5w);
  xpart z1 = xpart 0.5[gnd1, bbv.a];

  betw (bbv) 1,2;
  betw.u (I.i) gnd1,1;
  setlab.I.i.lab (btex$I_i$etex)(top)(top);
  abetw.u (gm) gnd5,1;
  setlab.gm.lab (btex$K_1 I_X$etex)(bot)(bot);

  abetw.d (current.X) bbv.c, gnd2;
  conn.v (gnd3, bbv.d) 0.3w;
  abetw.u (rhombus) gnd4, bbv.e;
  setlab.rhombus.lab (btex$K_2 V_o$etex)(bot)(bot);

  ioc2.a = z2;
  ioc1.t = T.u;
  conn.v (ioc1.a, gnd6) -0.1w;
  valign ioc1, ioc2;

  halign gnd1, gnd2, gnd4, gnd5, gnd6;
  edraw;

  label.top (btex$-$etex, ioc1);
  label.bot (btex$+$etex, ioc2);
  label (btex$V_o$etex, .5[ioc1,ioc2]);

  label.ulft ("1", bbv.a);
  label.urt ("2", bbv.b);
  label.llft ("3", bbv.c);
  label.lrt ("4", bbv.e);

  junction 1;

endfig;

beginfig(3)
  prepare (current.X, bbv,rm, gnd2,gnd3,gnd4, current.O, V.i, gnd1, gnd6);

  gnd1 = origin;
  z1 = (0,1.5w);
  z2 = (4w,1.5w);
%  z2 = 0.5[z3, bbv.b];
%  xpart z2 = xpart 0.5[gnd7, bbv.b];

  betw (bbv) 1,2;
  betw.u (V.i) gnd1,1;
  setlab.V.i.lab (btex$V_i$etex)(top)(top);

  abetw.d (current.X) bbv.c, gnd2;

  conn.v (gnd3, bbv.d) 0.3w;

  abetw.u (rm) gnd4,bbv.e;
  setlab.rm.lab (btex$K_1 I_X$etex)(bot)(bot);

  abetw.d (current.O) gnd6,2;

  halign gnd1, gnd2, gnd4, gnd6;
  edraw;

  label.ulft ("1", bbv.a);
  label.urt ("2", bbv.b);
  label.llft ("3", bbv.c);
  label.lrt ("4", bbv.e);

endfig;

beginfig(4)
  prepare (current.X, bbv,rm, gnd2,gnd3,gnd4, I.i, ioc1,ioc2, gnd1, gnd6);

  ypart gnd1 = 0;
  z1 = (0,1.5w);
  z2 = (4w,1.5w);
%  xpart z1 = xpart 0.5[gnd1, bbv.a];

  betw (bbv) 1,2;
  abetw.u (I.i) gnd1,1;
  setlab.I.i.lab (btex$I_i$etex)(top)(top);

  abetw.d (current.X) bbv.c, gnd2;
  conn.v (gnd3, bbv.d) 0.3w;
  abetw.u (rm) gnd4, bbv.e;
  setlab.rm.lab (btex$K_2 I_X$etex)(bot)(bot);

  ioc2.a = z2;
  ioc1.t = T.u;
  conn.v (ioc1.a, gnd6) -0.1w;
  valign ioc1, ioc2;

  halign gnd1, gnd2, gnd4, gnd6;
  edraw;

  label.top (btex$-$etex, ioc1);
  label.bot (btex$+$etex, ioc2);
  label (btex$V_o$etex, .5[ioc1,ioc2]);

  label.ulft ("1", bbv.a);
  label.urt ("2", bbv.b);
  label.llft ("3", bbv.c);
  label.lrt ("4", bbv.e);

endfig;

end