.PS
# Csource.m4
cct_init(svg_font(sans-serif,11bp__,2bp__))

# The default line separation is a bit small if the top line contains
# subscripts, so we space stacked lines explicitly:
define(`stbelow',`at last ""-(0,textht*1.5)')

define(`loffset',`+(textoffset,0)')
define(`roffset',`-(textoffset,0)')

define(`npair',`[define(`m4lr',ifelse(`$1',,l,r))
  J: mosfet(down_ dimen_,ifelse(`$1',,R,L),uHSDF,E)
     {["svg_it(Q`'svg_sub(`$2'))" ljust; "2N5464" ljust stbelow]\
       at J.nw+(ifelse(`$1',,-5bp__,5bp__),textht*0.75)}
  G: J.G
     line ifelse(`$1',,right,left) dimen_/4 from J.D
  Q: bi_tr(up_ dimen_,ifelse(`$1',,L,R),,E) with .B at Here
     {["svg_it(Q`'svg_sub(`$3'))" m4lr`'just; "2N4239" m4lr`'just stbelow] \
       at last [].ifelse(`$1',,e,w)}
  E: Q.E
  S: dot(at (Q.C,J.S))
     line from J.S to S then to Q.C ]')

define(`ppair',`[define(`m4lr',ifelse(`$1',,l,r))
  J: mosfet(down_ dimen_,ifelse(`$1',,R,L),dHSDF,E)
     {["svg_it(Q`'svg_sub(`$2'))" ljust; "2N3819" ljust stbelow] \
        at J.sw+(ifelse(`$1',,0,`4bp__'),-textht*0.6)}
  G: J.G
     line ifelse(`$1',,right,left) dimen_/4 from J.S
  Q: bi_tr(down_ dimen_,ifelse(`$1',,R,L),P,E) with .B at Here
     {["svg_it(Q`'svg_sub(`$3'))" m4lr`'just; "2N4236" m4lr`'just stbelow]}
  E: Q.E
  S: dot(at (Q.C,J.D))
     line from J.D to S then to Q.C ]')

  textht = textht*0.8
  R2: resistor(down_ dimen_)
    {["svg_it(R`'svg_sub(2))" ljust; "150`'svg_ohm" ljust stbelow] \
        at last [].e loffset }
    dot
  Q13: bi_tr(down_ dimen_,,P,E) with .E at Here
    {["svg_it(Q`'svg_sub(13))" rjust; "2N4236" rjust stbelow] at last [].w }
    line down 3.1*elen_ from Q13.C
  Q14: bi_tr(up_ dimen_,R,,E) with .C at Here 
    {["svg_it(Q`'svg_sub(14))" rjust; "2N4239" rjust stbelow] at last [].w }
    dot(at Q14.E)
  { line left_ dimen_*1.3 then up_ dimen_
  R1: potentiometer(up_ dimen_) with .Start at Here
    {["svg_it(R`'svg_sub(1))" ljust; "20k`'svg_ohm" ljust stbelow] \
       at last [].e loffset }
    { ground(at R1.T1) }
    line from R1.End to (R1.End,Q13.E) then to Q13.E }
  { dot(at Q13.C+(0,-elen_))
    line to (R1.R,Here)+(-dimen_/2,0)
    { arrowline(right_ dimen_/2); llabel(,i`'svg_sub(1)) }
    { move left 0.2}
  V1: gap(down_ dimen_,1); rlabel(+,V`'svg_sub(1),-) 
    line down_ dimen_/4 chop dotrad_ chop 0; ground(,T) }
  R3: resistor(down_ dimen_)
    {["svg_it(R`'svg_sub(3))" ljust; "150svg_ohm" ljust stbelow] \
      at last [].e loffset}
    dot(at Q13.C+(0,-2*elen_))
    line right_ dimen_/2
  A1: opamp with .In2 at Here;  "svg_it(A`'svg_sub(1))" at A1.C
    { "Nexus" rjust "SQ-10A" rjust at (A1.E,A1.s)+(0,-textht/2) }
    line left_ dimen_/4 from A1.In1 then up_ dimen_/2 then right dimen_
    dot
  { resistor(up_ elen_)
    {["svg_it(R`'svg_sub(14))" rjust; "19k`'svg_ohm" rjust stbelow] \
       at last [].w roffset}
    line to (Here,Q13.E) then to Q13.E }
    line to (A1.Out,Here)
    dot
  { line to A1.Out
    dot
    resistor(down_ to (Here,Q14.E))
    {["svg_it(R`'svg_sub(13))" ljust; "91k`'svg_ohm" ljust stbelow] \
       at last [].e loffset}
    line to Q14.E }
  R6: resistor(right_ dimen_)
    {["svg_it(R`'svg_sub(6))" ljust; "15k`'svg_ohm" ljust stbelow] \
      with .n at last [].sw+(0,-textoffset) }
    dot
    line to (Here,A1.In1) then right_ dimen_/4
  A2: opamp with .In1 at Here; {"svg_it(A`'svg_sub(2))" at A2.C }
    { "Nexus" rjust "SQ-10A" rjust at (A2.E,A2.s)+(0,-textht/2) }
    line left_ dimen_/4 from A2.In2
    ground

    dot(at A2.Out)
  DP1: npair(,3,4) with .E at (A2.Out,Q14.B)+(elen_*1.25,0)
#if 2 < 1 then {
    line from A2.Out to (A2.Out,DP1.G) then to DP1.G
    line from DP1.E to (DP1.E,R3.bottom); dot
  D4: reversed(`diode',up_ dimen_/2 from DP1.S)
  D3: reversed(`diode',up_ dimen_/2 from Here+(0,-dimen_/6))
    { "OMC-V" rjust "svg_it(D`'svg_sub(4))" rjust \
      "svg_it(D`'svg_sub(3))" rjust at last [].w }
  DP2: ppair(,1,2) with .E at (DP1.E,Q13.B)
  D1: diode(down_ dimen_/2 from DP2.S)
  D2: diode(down_ dimen_/2 from Here+(0,dimen_/6))
    {"svg_it(D`'svg_sub(1))" rjust "svg_it(D`'svg_sub(2))" rjust "OMC-V" rjust\
     at last [].w }
    dot(at (Here,A2))
    line to D2.bottom
    line from DP2.G to (A2.Out,DP2.G) then to A2.Out
    line from DP2.E to (DP2.E,R2.top); dot

  T: dot(at (DP1.E,A2)+(dimen_,0))
  DP3: npair(,7,8) with .G at (Here,DP1.G)+(dimen_/4,0)
    dot(at DP3.E)
    line to Q14.B
  DP4: ppair(,5,6) with .G at (DP3.G,DP2.G)
    dot(at DP4.E)
    line to Q13.B
    line from DP3.G to (T,DP3.G) then to (T,DP4.G) then to DP4.G
  R11: resistor(down_ dimen_ from DP4.S)
    {["svg_it(R`'svg_sub(11))" rjust; "20`'svg_ohm" rjust stbelow] \
      at last [].w roffset}
  D5: diode(up_ from DP3.S to (DP3.S,A2),Z)
    {["svg_it(D`'svg_sub(5))" rjust; "1N4729" rjust stbelow] \
       at last [].w roffset}
    line to R11.end
  C4: capacitor(right_ dimen_*1.3 from DP3.S,C)
    llabel(,svg_it(C`'svg_sub(4))); rlabel(,"0.68`'svg_micro(F)")
  C3: capacitor(right_ dimen_*1.3 from DP4.S,C)
    llabel(,svg_it(C`'svg_sub(3))); rlabel(,"0.68`'svg_micro(F)")
    dot
    dot(at (Here,R6))
  C2: reversed(`capacitor',left_ dimen_*1.3,C)
    rlabel(,svg_it(C`'svg_sub(2))); llabel(,"0.1`'svg_micro(F)")
    line to R6.end

  R5: resistor(up_ from R6.end to (R6.end,Q13.B))
    {["svg_it(R`'svg_sub(5))" ljust; "100k`'svg_ohm" ljust stbelow] \
       at last [].e loffset }
    dot(at R5.top-(0,dimen_/2))
    line left_ dimen_/2
    capacitor(down_ dimen_,C)
    {["svg_it(C`'svg_sub(1))" rjust; "1`'svg_micro(F)" rjust stbelow] \
      at last [].w roffset}
    ground(,T)

    line from DP4.E to (DP4.E,R2.bottom)
    resistor(up_ to (Here,R2.top))
    {["svg_it(R`'svg_sub(9))" ljust; "910`'svg_ohm" ljust stbelow] \
       at last [].e loffset}
    dot
    resistor(down_ from DP3.E to (DP3.E,R3.bottom))
    {["svg_it(R`'svg_sub(10))" ljust; "910`'svg_ohm" ljust stbelow] \
       at last [].e loffset}
    dot

    line from R5.top to (R5,Q13.E)
    resistor(right_ elen_)
    {["svg_it(R`'svg_sub(4))" ljust; "100k`'svg_ohm" ljust stbelow] \
      with .s at last [].nw+(0,1bp__)}
    line to (C4.end,Here) then to C4.end
    
  DP5: npair(L,11,10) with .E at (C4.end,DP1.E)+(elen_*0.8,0)
    line from DP5.E to (DP5.E,R3.bottom); dot
    line from R3.bottom to Here+(dimen_/2,0)
    dot(,,1)
    "svg_it(-E`'svg_sub(CC))" ljust at last [].e
  D6: diode(up_ from DP5.S to (DP5.S,A2),Z)
    {["svg_it(D`'svg_sub(6))" rjust; "1N4728" rjust stbelow] \
       at last [].w roffset}
  DP6: ppair(L,12,9) with .E at (DP5.E,DP2.E)
    line from DP6.E to (DP6.E,R2.top); dot
    line from R2.top to Here+(dimen_/2,0)
    dot(,,1)
    { "svg_it(E`'svg_sub(CC))" ljust at last [].e }
    resistor(down_ from DP6.S to (DP6.S,C2))
    {["svg_it(R`'svg_sub(12))" rjust; "20`'svg_ohm" rjust stbelow] \
       at last [].w roffset}
    dot
  { line to C2.e }
    line to D6.end

  Vr: dot(at (DP6.G,V1.top)+(dimen_/4,0))
    line from DP6.G to (Vr,DP6.G) then to (Vr,DP5.G) then to DP5.G
    reversed(`arrowline',right_ dimen_/2 from Vr); llabel(,i`'svg_sub(2))
  V2: gap(down_ dimen_,1); llabel(+,V`'svg_sub(2),-)
    { move right 0.2}
    line down_ dimen_/4 chop dotrad_ chop 0; ground(,T)

    dot(at (Vr,T))
    resistor(left_ to (DP6.E,Here))
    {["svg_it(R`'svg_sub(15))" ljust; "200`'svg_ohm" ljust stbelow] \
       with .s at last [].nw+(0,textoffset)}
    line to (DP1.E,Here)
    dot
#}

 command "</g>" # end font
.PE