X-Authentication-Warning: delorie.com: mail set sender to geda-help-bounces using -f
X-Recipient: geda-help AT delorie DOT com
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20120113;
        h=date:from:to:subject:message-id:mail-followup-to:references
         :mime-version:content-type:content-disposition:in-reply-to
         :user-agent;
        bh=b3U/RC6tEQ/gAfaAGTEH1RnFsxKVH3vR1324VuyRxXc=;
        b=hBf4i3HJjFLilNRhYPNkiJ49Yn2TIUV4nXmObpr2zPP9ScbcYedhDaTc7+zT0fTgRo
         OjzyCNCVm2r+G7/EANZQ2Aq+VRnGj37Ih3HNAwVIi+oFuAXHnSHz//LEokdyEeJGzRl6
         zGeh0lC4PWDjCREguCgyarH4iaVzN9B5s/DU3xrT6UebxlKU9OwXSymHo+1JK/silLtR
         AwrBcv7l4bwRX3u6aSNMg8iGezUQDESMrOepvauvWjVzd4D+AMP8upnkJI1ijR1zjij9
         wp5Z7KwPsEeqkTVoXek7twOsVeMcDio4orCA2fp6BUixORBOt37XDhhZGMK1yRHNgFii
         nBBQ==
Date: Mon, 29 Oct 2012 23:12:12 +0400
From: Vladimir Zhbanov <vzhbanov AT gmail DOT com>
To: geda-help AT delorie DOT com
Subject: Re: [geda-help] Another new user question on ngspice- how to export
 plots, and using current
Message-ID: <20121029191212.GB28209@localhost.localdomain>
Mail-Followup-To: geda-help AT delorie DOT com
References: <a122194d067751cf4d45af085e91cf10 DOT squirrel AT webmail DOT strucktower DOT com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <a122194d067751cf4d45af085e91cf10.squirrel@webmail.strucktower.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Reply-To: geda-help AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: geda-help AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk

On Sat, Oct 27, 2012 at 07:51:55PM -0700, keitho AT strucktower DOT com wrote:
> Hi all-
> 
> I'm using ngspice on Linux/Debian. I guess the graphing/plots are done
> using X11 by default? I haven't figured out how to export my graphs to
> PNG's so that I can send them in emails to folks helping me learn. Is
> there a way to do that, or do you recommend using a different program for
> graphing the plots that provides that feature?

I'd suggest you to try out gnuplot or pyxplot.

> 
> Second question: in general, I'm confused about the way ngspice handles
> current. Just as an example, here's a trivial netlist of a circuit using a
> current source to drive the base:
> 
> common-emitter amplifier
> i1 0 1 dc
> q1 2 1 0 mod1
> r 3 2 5000
> v1 3 0 dc 15
> .model mod1 npn
> .control
> dc i1 0 50u 2u
> run
> plot v(2)
> .endc
> .end
> 
> Here's the output of display:
> 
> ngspice 2 -> display
> Here are the vectors currently active:
> 
> Title: common-emitter amplifier
> Name: dc1 (DC transfer characteristic)
> Date: Sat Oct 27 22:39:55  2012
> 
>     V(1)                : voltage, real, 26 long
>     V(2)                : voltage, real, 26 long
>     V(3)                : voltage, real, 26 long
>     i-sweep             : voltage, real, 26 long [default scale]
>     v1#branch           : current, real, 26 long
> 
> 
> The graph of this is the correct shape, but I'm confused about why it is
> sweeping voltage rather than current. Can someone explain what's going on
> here, or point to a tutorial that would help?

Looks like a bug in ngspice. You'd better ask this in one of ngspice
mailing lists (you can find their addresses at
http://ngspice.sourceforge.net/faq.html). Or try to use gnucap and
compare results. There are some differences between the two programs in
the netlist format they're using. Be prepared.

-- 
http://vzhbanov.byethost33.com