I've been playing with gnucap for a week.... but can't seem to get a test opamp integrator circuit to work. Actually I can't get any circuit with more than 2 non-linear elements to work. The circuit in question is a basic integration circuit using an LM741 opamp, two resistors, one capacitor, and a voltage controlled switch.
The input should be a long pulse, and the output should be a ramp.
When I try to run the analysis, I get: .... did not converge 27. did not converge very backward time step convergence failure, reducing (itl4) newtime=5.960464e-13 rejectedtime=1.192093e-12 oldtime=0.000000e+00 using=1.000000e-12 tried everything, still doesn't work, giving up ..... or in other words, it bombs.
I've attached my p.sch file.
I'm running gnucap 0.35 on debian 6 with emacs 23.
I should preface this with the disclaimer that I know enough electromic to be dangerous..... but I'm trying to learn...
I've been using the Makefile method of Johannes Bauer.
Here's the data on what I'm doing:
* Contents of p.hdr follow: .include ../models/LM741_NS.mod ..model swmod SW( von=1.0 voff=0.5) Vss (Vss 0) DC 0 AC 26 SIN(0 26 60hz) Vdc (+12V 0) DC 12 Vdc (0 -12V) DC 12 Vee (Vee 0) pulse( 0 10 0.5 4 10m 10m) S1 +12V Vpin Vee 0 swmod