updates to optran description and example.

README.optran

@@ -12,10 +12,10 @@ If this fails:
 
 If this again fails, bail out.
 
-In tghis branch a fourth method is added:
+In this branch a fourth method is added:
 4) Start a transient simulation for a specific amount of time.
    Keep all data local. Keep the matrix values as an
-   operating point for the simualtion following.
+   operating point for the simulation following.
 If this fails, finally stop.
 
 The time for transient is determined a priori. If a transient
@@ -34,3 +34,13 @@ option gminsteps=0
 
 Step 3 may be skipped by 
 option srcsteps=0
+
+The transient op calculation uses the 'UIC' flag for its startup.
+Basically two applications come to mind: You may use this with
+constant voltage and current sources and simulate until the 
+output is stable. A method to automatically stop the op transient
+simulation when all nodes have become stable, might be desirable,
+but has not yet been implemented.
+One also may use the optran for a first transient simulation, maybe
+with different step sizes, before the next (tran, ac, pz, noise)
+simulation is commencing.

examples/optran/F5TurboV2thermal-optran.cir

@@ -37,7 +37,7 @@ D2b1 Net-_D2a1-Pad2_ -32 DMOD
 XP3 Net-_P3-Pad1_ 0 Net-_P3-Pad1_ RPOT value=200 ratio=0.85
 XP1 Net-_P1-Pad1_ +32 +32 RPOT value=5k ratio=0.18
 XP2 Net-_P2-Pad1_ -32 -32 RPOT value=5k ratio=0.18
-V3 in 0 sin(0 2 1k)
+V3 in 0 dc 0 ac 1 sin(0 2 1k)
 JQ1 Net-_P1-Pad1_ Net-_Q1-Pad2_ Net-_P3-Pad1_ 2SK170
 JQ2 Net-_P2-Pad1_ Net-_Q1-Pad2_ Net-_P3-Pad1_ 2SJ74
 MQ5 out Net-_Q5-Pad2_ Net-_D1a1-Pad2_ Q5tj Q5tc IRFP240 thermal

examples/optran/script-optran.txt

@@ -8,8 +8,10 @@ if $?sharedmode
 version
 rusage
 else
-* script for standard ngspice
-*option noinit
+*** script for standard ngspice
+* Start optran without first iteration, 
+* without gmin stepping and without src stepping
+* optran duration 4s, step size 10 ms
 optran 1 0 0 4 1e-2 0
 tran 1u 10m
 echo
@@ -26,15 +28,18 @@ set xbrushwidth=1
 * input and output voltages
 plot in out
 * power supply currents
-plot V1#branch V2#branch ylimit -50 50
-plot V1#branch V2#branch ylimit -10 10
+*plot V1#branch V2#branch ylimit -50 50
+plot V1#branch V2#branch ylimit -15 15
 * output current
 plot @rl1[i] 
-plot @rl1[i] xlimit 0 5m ylimit -0.3 0.3 
+*plot @rl1[i] xlimit 0 5m ylimit -0.3 0.3 
 * resistance of thermistor2 TH1, TH2
 let rth1 = (v("net-_d3a1-pad1_") - v("net-_r11-pad1_")) / (@b.xth1.brtherm[i] + 1n)
 let rth2 = (v("net-_d1a1-pad2_") - v("net-_r12-pad1_")) / (@b.xth2.brtherm[i] + 1n)
 settype impedance rth1 rth2
 plot rth1 rth2 ylimit 0 5k
+ac dec 10 1 1Meg
+plot db(out)
+plot cph(out)
 end
 .endc