On Wednesday 01 August 2007, Crispy wrote: > I'm trying to simulate a circuit which right now consists of > only a high voltage rectifier, but gnucap is giving me > strange errors and the output stops right after the first > half-cycle of the AC source. Attached is primary.ckt (the > circuit file), primary.out (the output data file), and > gnucap.out (the stdout/stderr data from gnucap). Any help is > greatly appreciated.
This one was held for moderation because of attachments. Like the other one, add a parallel conductance to the diodes. Sometimes making it too ideal causes trouble. You have a string of diodes in series. This doesn't work in practice. You need to put resistors in parallel with the diodes to assure equal sharing of the voltage. Without the resistors, the reverse voltage would probably be shared unequally, leading to breakdown and failure. The warning: ======= initial step rejected:Cj.D1.X1.Xrect new=3.25363e-07 old=1e-06 required=5e-07 ======= just says that the initial step was rejected, and it had to try again. You can suppress these warnings with ".option nowarn". I don't recommend suppressing warnings. They are a hint that something is happening that you may not otherwise be aware of. In this case, you asked for time stepping of .0001 seconds (1e-4) but the actual values in the circuit require an initial step of 3.2e-7. It automatically makes a tiny first step, some fraction of the step you ask for, in this case "old=1e-06", .. 100x smaller. After actually doing it, and checking it for accuracy, it was determined to be not good enough. If it was close (required=5e-07) it would let it slip by. That is still not good enough, so it throws away the calculation, backs up, and starts over with smaller steps, this time "new=3.25363e-07". This is all for the "initial step", the one that comes immediately after zero. You may think that this is a slow circuit, so why does it need such a small time step? The answer is so it can correctly simulate the tiny strays. If you don't care about the effect of stray capacitance, you can say ".option method=euler". Otherwise, it needs a tiny time step to avoid a problem known as "trapezoidal ringing", where you get a junk response at half of the sampling frequency. _______________________________________________ Help-gnucap mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-gnucap
