.PS include(pstricks.m4) scale=25.4 cct_init vsp=25 hsp=25 define(`termrad_',`sourcerad_/4') define(`terminal',`circle rad termrad_') O: (0,0) move to O R1: resistor(up_ vsp);llabel(,R_1,);rlabel(,1\;\text{k}\Omega,) line right hsp { dot(at Here) IS: source(down_ to (Here.x,O.y),I,,R);rlabel(,i_s,);llabel(,5\;\text{mA},) dot(at Here)} VS: source(right_ hsp,V,,R);llabel(,v_s,);rlabel(,5\;\text{V},) { line right hsp*.75 TA: terminal} dot(at Here) R3:resistor(down_ to (Here.x,O.y));rlabel(,R_3,);llabel(,3\;\text{k}\Omega,) dot(at Here) { line right hsp*.75 TB: terminal} R2: resistor(left_ to IS.end);rlabel(,R_2,);llabel(,800\;\Omega,) line to O "$a$" at TA.n above "$b$" at TB.s below "$+$" at TA.s below "$-$" at TB.n above "$v_{ab}$" at 1/2 between TA and TB .PE