.PS
# Reg723.m4
# see Horowitz and Hill p 600
cct_init
  command "{\small\sf"

# "+7.15V"
 R1: resistor(down_ dimen_*3/4); rlabel(,\shortstack[r]{$R_1$\\1.15k})
 R2: potentiometer(down_ dimen_) with .Start at Here
   rlabel(,\shortstack[r]{$R_2$\\2.0k})
   "$\mathstrut V_{\hbox{adj}}$" at R2.T1 below
 R3: resistor(down_ dimen_ from R2.End); rlabel(,\shortstack[r]{$R_3$\\4.02k})
   ground

   line right_ dimen_*4/3 from R2.T1
 A: opamp(,,,,R) with .In1 at Here

   line right_ dimen_*3/4 from A.Out
 B1: dot
 Q2: bi_tr(up_ dimen_) with .B at Here
   line right_ dimen_ from Q2.E
 Q1: bi_tr(up_ dimen_*3/2)  with .B at Here; heatsink(at Q1.e+(dimen_/2,0),,D)
   "heat" ljust at last [].e+(dimen_/5,0) "sink" ljust
   dot(at Q1.E)
   resistor(down_ dimen_*3/2); llabel(,\shortstack[l]{0.25$\Omega$\\3W})
 P5: dot

 Q3: bi_tr(up_ dimen_,R) with .B at (Q2.C.x,Q1.E.y); dot(at Q3.C)
   { line to Q2.B }
   resistor(left_ dimen_ from Q1.E); llabel(,"100")
   line to Q3.B
   line from Q3.E to (Q3.E,P5) then to P5+(dimen_,0)
 Out: "\shortstack[l]{+5V\\2A}" ljust
   dot(at P5+(dimen_/2,0))
   capacitor(down_ dimen_,C+); ground(,T)
   rlabel(,\shortstack[r]{10$\mu$F\\15V})

 Vref: box wid boxwid/2 ht boxht/2 with .w at (A.E.x,A.n.y+dimen_/3) \
   "$V_{\hbox{ref}}$"
 Bx: box thick 0.4 wid Q2.C.x-A.w.x+dimen_/2 rad 0.1 \
     ht Vref.n.y-Q3.E.y+dimen_/3 with .sw at (A.In1.x-dimen_/7,Q3.E.y) dashed
   "723" at Bx.n above

   line from Vref.w to (Bx.w,Vref.w)
   { "$V_{\hbox{ref}}$" above rjust }
   continue to ((R1.x+Here.x)/2,Here.y); continue to (Here,R1.start) \
    then to R1.start
   "$+$7.15V" above ljust

 P6: dot(at P5-(dimen_*2/3,0))
   line from Q3.C left_ dimen_/2 then down_ Q3.C.y-Bx.s.y
 Cp: capacitor(down_ dimen_*3/2); rlabel(,"100pF"); dot
   line from A.In2 left_ dimen_/2 then down_ A.In2.y-Cp.end.y then to Cp.end
 R4: resistor(right_ to (P6,Here)); rlabel(,"$R_4$ 1.5k"); line to P6
    
   line from A.SE to (A.SE,Bx.s); ground
   "COMP" at (Cp,Bx.s) below rjust
   "CS" at (Q3.E,Bx.s) below ljust
   "CL" at (Bx.e,Q1.E) below ljust
   "NI" at (Bx.w,A.In1) rjust above
   "$V_{\hbox{out}}$" at (Bx.e,Q1.B) above ljust
   "INV" at (Bx.w,A.In2) rjust above

   line from A.NE to (A.NE.x,Bx.n.y+dimen_/2)
   { "$V_{+}$" at (Here,Bx.n) above rjust }
   continue to (Out,Here)
#  {"$+V_{\hbox{in}}$ (unreg)" rjust at Here+(0,15bp__) "$+$9.5V (min)" rjust}
   {"\shortstack{$+V_{\hbox{in}}$ (unreg)\\$+$9.5V (min)}" below}
   {dot(at (Q2.C,Here)); line to Q2.C
    "$V_C$" at (Here,Bx.n) above rjust }
   dot(at (Q1.C,Here)); line to Q1.C
   "\shortstack[l]{$Q_1$\\TIP41}" ljust

  command "}%"
.PE