.PS
cct_init

# Usual defs...
qrt=dimen_/4;
hlf=dimen_/2;
dim=dimen_;

dot;line;dot
move down_ then left_;dot
line right_ 3*dim;dot

move left_ ;dot
consource(up_,V); rlabel(,\left(1+\frac{R_2}{R_1}\right)v_i,)
line right_;dot
move left_ 2*dim then down_ hlf
"$v_i$"
move down_ hlf; dot

"\tiny NonInvertEquiv" at (3*dim, -1.5*dim) rjust_ 
.PE