Rick said:
Yep. I agree - I came to the same conclusion shortly after I'd posted
my reply. My method produces the impedance of the unloaded circuit.
I think the best bet is to leave the load in, but not fiddle around
with this voltage source stuff - just pump 1 Amp AC in, an accept
that the resulting impedance is the parallel combination of the
circuit's output impedance and the load impedance. Working back
to the circuit's o/p impedance is then trivial if the load is passive.
I'd swap a bucket of "convenience" features if your software offered
either of:
1. Ability to temporarily disable any given components in the schematic
without having to delete them.
Well, you can just move them to a blank piece of the page. (use the
rubberband toolbar button to temporally disable the rube). However...
You can do exactly what you wish. Double-click on the symbol to popup
its set-up dialog. Use the PCB data tab, and lo and behold, check boxes
to include in the spice and/or pcb netlist.
2. Override component model parameters from within the schematic without
having to edit the part library first. I hate having components called
"hi beta", "hi beta zero tempco" - I just want to change the damned
parameter!
Does SS do these?
Sort off. There is the docked preview window (top left main window)
where you can edit the model directly (but it does via the lib), or you
can edit the model from the symbol, set-up dialog. However, this effects
all symbols with that model name. However...
You can have 3 sets of models, easily *switchable*. The model tab of the
set-up has checks for weak, nominal and strong. If you switch this from
its default of normal, it will try and find that model variation, or
copy the nominal model. You can then change those weak or strong model
parameters and those parameters will only effect other models that are
also connected to that specific model type. This allows quick check out
of different model variations simply by clicking those buttons.
However...Changing these weak and strong parameters will effect the
automatic WC runs for that model type as it uses this data. However...
you shouldn't really have to do what you suggest above, as that is what
the auto WC (worst case) is *designed* to do for you already. It already
has sensible WC values set-up, e.g. max/min hfe, etc. I have tried to
anticipate what is required so that the user don't have to worry about
these things. The WC reruns should give a pretty good (overestimate) of
what variations will occur without the user having to manually do this.
Oh.. I reduced the price a bit today...
Kevin Aylward
[email protected]
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.