Re: gEDA-user: Verifying ngspice with an RLC sample in given link

["Daniel B. Thurman" <dant@xxxxxxxxx>]

On 03/02/2011 10:30 AM, Daniel B. Thurman wrote:
> On 03/02/2011 10:05 AM, Daniel B. Thurman wrote:
>> On 03/02/2011 09:55 AM, Vladimir Zhbanov wrote:
>>> On Tue, Mar 01, 2011 at 05:59:42PM -0800, Daniel B. Thurman wrote:
>>>> Hi, I found the time to go back to my past
>>>> and revisit spice (used older Berkeley spice then)
>>>> so I tried a simple RLC circuit from the following
>>>> link and using ngspice:
>>>>
>>>> http://www.allaboutcircuits.com/vol_2/chpt_6/3.html
>>>>
>>>> Unfortunately, I was not able to duplicate the
>>>> plots as shown in the above link.  I am assuming
>>>> that the author is using something other than ngspice
>>>> or I am doing something wrong?
>>>>
>>>> Attached is the rlc.sch file with the same circuit sans
>>>> the circuit netlist but it can be easily generated:
>>>>
>>>>> gnetlist -o rlc.cir -g spice-sdb rlc.sch
>>>> The contents of rlc.cir is:
>>>>
>>>> *********************************************************
>>>> * Spice file generated by gnetlist                      *
>>>> * spice-sdb version 4.28.2007 by SDB --                 *
>>>> * provides advanced spice netlisting capability.        *
>>>> * Documentation at http://www.brorson.com/gEDA/SPICE/   *
>>>> *********************************************************
>>>> *==============  Begin SPICE netlist of main design ============
>>>> L1 0 3 10mH
>>>> C1 3 2 10uF 
>>>> R1 1 2 1 
>>>> V1 1 0 dc 0 ac 1 sin
>>>> .end
>>> L1 is 100mH there. Could it help?
>>>
>>> --
>>> VZh
>> Duh oh!  That worked!
>> Reminder to self: Get some hi-powered glasses and strong coffee!
>>
>> Thanks!
> There seems to be a problem; v(3) plot is inverted,
> otherwise the other nodes probes look good. Perhaps
> this has to do with "vm" which is not a recognized
> vector, so I just used "v" for node probes. Other than
> that, it looks good.
>
>
>
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Problem solved.  It was 'vm'  and I recognized C/L are
inverted plot WRT each other as expected. So to get
the mags, one has to do:

plot 100*mag(v1#branch) mag(v(2,3)) mag(v(3))

which amounts to the same thing.

All is well & thanks for pointing out the error!



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