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Re: gEDA-user: Simulation with Potentimeter



Hi Stuart,

I did some simulations today using ".dc name start end stepsize" so that
would mean for your example

Resistor sweep test circuit
r1 0 1 100
r2 1 2 1k
v1 0 2 1v
.dc r1 100 1k 100
.end

This way it works and generates values, but shouldn't the result be a
straight line?


Tobias


Am Son, den 04.01.2004 schrieb Stuart Brorson um 17:39:
> I tried doing an analysis in tclspice/ngspice using a simple resistor
> dividor.  Here's the output:
> 
> ---------------------  Tclspice log  -----------------------
> ******
> ** tclspice-0.2.15 : Circuit level simulation program
> ** The U. C. Berkeley CAD Group
> ** Copyright 1985-1994, Regents of the University of California.
> ** Please submit bug-reports to: ngspice-devel@lists.sourceforge.net
> ** Creation Date: Sun Dec 21 22:06:36 EST 2003
> ******
> 
> Circuit: * Resistor sweep test circuit
> 
> tclspice 362 -> listing
> 	* Resistor sweep test circuit
> 
>      2 : r1 0 1 1k
>      3 : r2 1 2 1k
>      4 : v1 0 2 1v
>      5 : .dc r1 100 0 1k
>      6 : .end
> tclspice 363 -> run
> Doing analysis at TEMP = 300.150000 and TNOM = 300.150000
> ** Resistor sweep is highly alpha code
> **Results may not be accurate.
> 
> No. of Data Rows : 1
> tclspice 364 -> plot V(1)
> tclspice 365 -> print V(1)
> v(1) = -5.00000e-01
> 
> tclspice 364 -> exit
> Warning: the following plots haven't been saved:
> dc1	* Resistor sweep test circuit, DC transfer characteristic
> 
> Are you sure you want to quit (yes)? yes
> --------------------  End of tclspice log  ---------------------
> 
> Unfortunately, the result is not a vector, so the sweep didn't work as
> one would want, at least in tclspice.  I'll add this to my (ever-growing)
> list of things needing fixin' in that prog.  Or maybe my head is wedged 
> & I have not entered the right command sequence?  
> 
> Nonetheless, if you have a simulator which works, I'd recommend that you
> use the "spice-directive" symbol in the spice directory to input 
> the ".dc r1 100 0 1K" string directly into your netlist.  "Spice-directive"
>  simply outputs the string you place into the "value" attribute.  Just 
> delete the "file" attribute -- you don't need it.  That way you can do 
> simulations with a swept resistor.  
> 
> Alternatively, if you have a simulator
> which admits swept parameters, you can just type the sweeping command
> directly into the "spice-directive" symbol.
> 
> Stuart
> 
> Quoting "mailinglists@my-mail.ch" <mailinglists@my-mail.ch>:
> > I just had a look at the source code and it seems as if it's just a DC
> > analysis like:
> > 
> > R2 3 1 100 
> > R1 2 3 100 
> > V1 2 1 5
> > .DC R1 100 1k 100
> > .END
> > 
> > Tobias
> > 
> > 
> > Am Sam, den 03.01.2004 schrieb Stuart Brorson um 23:32:
> > > 
> > > I looked through the docs I have, but found no reference to resistor
> > > sweeps in ngspice.  Do you know what the syntax is for this analysis?
> > > (Yes, I could grep through the tclspice code for it, but that is a
> > > real PITA . . . . )
> > > 
> > > Stuart
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