Re: gEDA-user: Expert help needed - gschem/ngspice etc...

[John Doty <jpd@xxxxxxxxxxxxx>]

Slotting is a fabrication concept. SPICE doesn't understand slotting.  
Don't use it in your sims.

In general, schematics you simulate are not schematics you use for  
board layout: they contain extra things like independent sources and  
parasitics. There are even problems of convention: board design uses  
"U" for chips, but a SPICE subcircuit requires "X". It's a pain, but  
I've never seen an EDA tool that could handle the relation between  
simulation and fabrication seamlessly. So, keep separate schematics  
for sims and fab. Cut and paste is useful.

Remember that the spice-sdb netlister doesn't care about pinnunber:  
it's pinseq that matters.

On Jul 31, 2006, at 7:43 PM, John Coppens wrote:

> Hi all.
>
> What's the correct way to define things (mainly the symbol) when,
> defining a dual or quad opamp? Here are the problems I bounced  
> against:
>
> 1) The quad or dual evidently has common power lines.
>
> 2) The model defines the pins in order +, -, V+, V-, and output (which
> seems quite common)
>
> 3) How do I define the slotdefs? The pins for v+ and v- are drawn  
> on the
> circuit, not just defined as attributes. Can I repeat the pin numbers
> unpunished?
>
> 4) If I do the above, I get gnetlist -g drc2 complaining that the  
> second
> op-amp isn't in the circuit.
>
> 5) If, after giving up, I put it in the circuit, and connect its  
> pins, so
> it won't complain again, I get
>
> "Invalid wanted_pin passed to get-nets [unknown]" (5 times)
>
> 6) If I try to define a slot=1 for this component, gschem crashes.
>
> 7) And, to top things off, I can't seem to get this running with  
> ngspice
> - I get a report of 'singular matrix'es and non-convergence.
>
> Would someone please have a look at the sym and circuit? As everything
> is small, I've attached all files (including the model).
>
> Thanks.
> John
> <evm_input.sch>
> <mc33078-1.sym>
> <MC33078.mod>
>
>
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John Doty              Noqsi Aerospace, Ltd.
jpd@xxxxxxxxxxxxx




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