Re: gEDA-user: Multivibrator Simulation

[Michael B Allen <ioplex@xxxxxxxxx>]

On Tue, Jun 23, 2009 at 12:28 PM, al davis<ad252@xxxxxxxxxxxxxxxx> wrote:
> On Tuesday 23 June 2009, Michael B Allen wrote:
>> I'm trying to run a simple multivibrator simulation but both
>> SPICE and GNU-Cap do not yield anything that even oscillates.
>> Here is the circuit:
>>
>>   http://207.192.69.113/~miallen/mv_1.pdf
>
> It would help if you include a netlist, so I can try it.

Ok, here's the netlist:

* /usr/bin/gnetlist -v -g spice-sdb -o /home/miallen/EE/mv_1.ckt
/home/miallen/EE/mv_1.sch
*********************************************************
* 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 ============
Q2 output 2 0 2N3904
.MODEL 2N3904 NPN (Is=6.734f Xti=3 Eg=1.11 Vaf=74.03 Bf=416.4 Ne=1.259
Ise=6.734 Ikf=66.78m Xtb=1.5 Br=.7371 Nc=2 Isc=0 Ikr=0 Rc=1 Cjc=3.638p
Mjc=.3085 Vjc=.75 Fc=.5 Cje=4.493p Mje=.2593 Vje=.75 Tr=239.5n
Tf=301.2p Itf=.4 Vtf=4 Xtf=2 Rb)
V1 4 0 DC 9V
R4 output 4 0.999K
Q1 1 3 0 2N3904
.MODEL 2N3904 NPN (Is=6.734f Xti=3 Eg=1.11 Vaf=74.03 Bf=416.4 Ne=1.259
Ise=6.734 Ikf=66.78m Xtb=1.5 Br=.7371 Nc=2 Isc=0 Ikr=0 Rc=1 Cjc=3.638p
Mjc=.3085 Vjc=.75 Fc=.5 Cje=4.493p Mje=.2593 Vje=.75 Tr=239.5n
Tf=301.2p Itf=.4 Vtf=4 Xtf=2 Rb=10)
R3 1 4 1.001K
R2 3 4 15K
R1 2 4 15K
C2 output 3 10uF
C1 1 2 10uF
.end

> You need to explicitly start the oscillator.

I'm not having any luck with this. It seems the syntax of netlist vs.
interpreter mode commands vs. gspiceui fields is different enough that
it's totally unclear as to how to achieve non-trival things.

First, do I want to use GNU-Cap or NG-Spice?

Also, what timing do I want? I was thinking something like 50ms -
100ms in 1ms increments reasoning that it will take time for the
oscillation to start.

Regarding simulating power on, I don't recognize the format on the page cited:

  Vcc (vcc 0) pulse(iv=0 pv=12 rise=.01)

My netlist above does not have parenthesis. And it seems gspiceui
overrules the voltage source properties anyway?

Similarly I'm not sure where the "OFF" property would go. I tried
sticking it in the parameters of the .MODEL description but gspiceui
choked on it.

What is the definitive guide for interactive mode?

Mike

-- 
Michael B Allen
Java Active Directory Integration
http://www.ioplex.com/


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