diff --git a/test-hertz-1.cir b/test-hertz-1.cir
index 63d8561e6..e6fc2b44f 100644
--- a/test-hertz-1.cir
+++ b/test-hertz-1.cir
@@ -1,23 +1,30 @@
+* test ASRC ac analysis with regard to HERTZ and tc1
 * (exec-spice "ngspice %s" t)
 
-* holgers save all i, was saved der bei ac ??? id ist reell ?
-vin 1 0 dc = 5 ac = 1
+* Test the implementation of the ASRC device with regard to HERTZ and tc1
+* This circuit is deliberatly designed in such a way as to make
+*   the original incorrect implementation of the ASRC model obvious,
+*   which incorrectly evaluated the ASRC expression for every frequency
+*      to recalculate the operating point of the whole circuit
+*    instead of calculating the operating point from the expression
+*      when HERTZ=0
+*   The diode is deliberatly attached here to expose the difference.
+* A second aspect is to check the tc1 parameter of the ASRC
+
+.temp 27.0
+
+v0  1 0  dc = 5 ac = 1
+
+b1  1 2  v = 'i(b1) * 1k * (1 + sqrt(hertz/1kHz))' tc1 = 0.01
 
-*r1  1 2 1k
-*br1 1 2 v='i(br1)*1k'
-br1 1 2  v = 'i(br1) * 1k * (1 + sqrt(hertz/1kHz))'
 c2  2 0  30u
-d2  2 0  dplain
+d2  2 0  dplain temp=27.0       $ keep diode at 27.0 for simplicity
 
-.model dplain   d(is=1.0f)
-
-*uT = kT/e
-*i = is * (e^(u/uT - 1)
-*di/du = is * e^~ * kT/e = (i + is) / uT
+.model dplain d()
 
 .control
 
-* default is 1e-12, yet gold is calculated with none
+* default is 1e-12, but our golden solution is derived without
 set gmin = 0
 
 set reltol = 1e-15
@@ -25,55 +32,65 @@ set vntol  = 1e-15
 *set abstol = 1e-15
 *set chgtol = 1e-24
 
-*! display
-
 let uT = boltz * (273.15 + 27.0) / echarge
 
-* these boltz and echarge are literal from devices/dio
+* These 'boltz' and 'echarge' are literal copied from src/spicelib/devices/dio
 *   and differ slightly from our global visible ones
 let uT = 1.3806226e-23 / 1.6021918e-19 * (273.15 + 27.0)
 
-* echo no arity FIXME !!
-*print uT (uT - 0.0258642)
-
-*! print uT uT-0.0258641863845515
-
 op
 
-let r  = 1k
-let is = 1f
-let u0 = 5.0
+let u0 = @v0[dc]
+let c2 = @c2[capacitance]
+let is = @dplain[is]
+
+let gold_r1_dc = 1k * (1 + ($temp - 27.0) * 0.01)
+
+* golden solution of the operating point
+*   uT = kT/e
+*   i = is * (e^(u/uT - 1)
+*   di/du = is * e^~ * kT/e = (i + is) / uT
 
 let cd = 1m
-repeat 5
-let f = cd * r + uT * log(cd/is + 1) - u0
-let f_hat = r + uT / (cd/is + 1) / is
-let cd = cd - f/f_hat
-let err = cd/-i(vin) - 1
-*print cd+i(vin)
-print err
+repeat 6
+  let f = cd * gold_r1_dc + uT * log(cd/is + 1) - u0
+  let f_hat = gold_r1_dc + uT / (cd/is + 1) / is
+  let cd = cd - f/f_hat
+  let err = cd/-i(v0) - 1
+  echo "iteration: err = $&err"
 end
 
-*! show all
-*! showmod all
+let gold_cd = cd
+let gold_gd = (cd + is) / uT
+let gold_vd = uT * log(cd/is + 1)
 
-let r1_dc = 1k
-let d2_gd = @d2[gd]
-let c2    = @c2[capacitance]
+let err_cd = @d2[id]/gold_cd - 1
+let err_gd = @d2[gd]/gold_gd - 1
+let err_vd = @d2[vd]/gold_vd - 1
 
-*! print all
+* compare golden diode model with ngspice solution
+* expect errors of several double floating ULP, roughly 1E-15
+
+echo "INFO: err_cd = $&err_cd"
+echo "INFO: err_gd = $&err_gd"
+echo "INFO: err_vd = $&err_vd"
+
+* now do the 'ac' analysis
 
 ac dec 100 1 1e6
 
 let s = 2*pi*i * frequency
 
-let r1_ac = 1k * (1 + sqrt(frequency/1kHz))
-let H = 1/(1 + r1_ac * (s * op1.c2 + op1.d2_gd))
+let gold_r1_ac = op1.gold_r1_dc * (1 + sqrt(frequency/1kHz))
+let gold_H = 1 / (1 + gold_r1_ac * (s * op1.c2 + op1.gold_gd))
 
-let err = v(2)/H - 1
-print vecmax(abs(err))
+let err = v(2)/gold_H - 1
+let err_H = vecmax(abs(err))
 
-plot abs(H) abs(v(2))
+echo "INFO: err_H = $&err_H"
+
+* expect errors of several double floating ULP, roughly 1E-15
+plot abs(gold_H) abs(v(2))
 plot abs(err)
 
 .endc
diff --git a/test-hertz-1t.cir b/test-hertz-1t.cir
deleted file mode 100644
index b350f1530..000000000
--- a/test-hertz-1t.cir
+++ /dev/null
@@ -1,82 +0,0 @@
-* (exec-spice "ngspice %s" t)
-
-.temp 37.0
-
-* holgers save all i, was saved der bei ac ??? id ist reell ?
-vin 1 0 dc = 5 ac = 1
-
-*r1  1 2 1k
-*br1 1 2 v='i(br1)*1k'
-br1 1 2  v = 'i(br1) * 1k * (1 + sqrt(hertz/1kHz))' tc1=0.01
-c2  2 0  30u
-* FIXME, the diode doesn't behave as expected when temp != 27.0
-d2  2 0  dplain temp=27.0
-
-.model dplain   d(is=1.0f)
-
-*uT = kT/e
-*i = is * (e^(u/uT - 1)
-*di/du = is * e^~ * kT/e = (i + is) / uT
-
-.control
-
-* default is 1e-12, yet gold is calculated with none
-set gmin = 0
-
-set reltol = 1e-15
-set vntol  = 1e-15
-*set abstol = 1e-15
-*set chgtol = 1e-24
-
-*! display
-
-let uT = boltz * (273.15 + 27.0) / echarge
-
-* these boltz and echarge are literal from devices/dio
-*   and differ slightly from our global visible ones
-let uT = 1.3806226e-23 / 1.6021918e-19 * (273.15 + 27.0)
-
-* echo no arity FIXME !!
-*print uT (uT - 0.0258642)
-
-*! print uT uT-0.0258641863845515
-
-op
-
-let r  = 1k * (1 + 10 * 0.01)
-let is = 1f
-let u0 = 5.0
-
-let cd = 1m
-repeat 5
-let f = cd * r + uT * log(cd/is + 1) - u0
-let f_hat = r + uT / (cd/is + 1) / is
-let cd = cd - f/f_hat
-let err = cd/-i(vin) - 1
-*print cd+i(vin)
-print err
-end
-
-*! show all
-*! showmod all
-
-let r1_dc = 1k * (1 + 10 * 0.01)
-let d2_gd = @d2[gd]
-let c2    = @c2[capacitance]
-
-*! print all
-
-ac dec 100 1 1e6
-
-let s = 2*pi*i * frequency
-
-let r1_ac = 1k * (1 + sqrt(frequency/1kHz)) * (1 + 10 * 0.01)
-let H = 1/(1 + r1_ac * (s * op1.c2 + op1.d2_gd))
-
-let err = v(2)/H - 1
-print vecmax(abs(err))
-
-plot abs(H) abs(v(2))
-plot abs(err)
-
-.endc