Re: gEDA-user: Multivibrator Simulation

[John Doty <jpd@xxxxxxxxx>]

On Jun 23, 2009, at 9:45 AM, 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
>
> Is there anything wrong with this? Is there any trick to getting
> something like this to work?

You've created a simulation of a pencil perfectly balanced on its  
point. Break the symmetry somehow. Lots of ways to do it:

Change one of your resistor values a skosh. They won't be perfectly  
equal in reality anyway.

Or use different transistor models.

Or force one of the node voltages away from equilibrium with a .IC  
command and specify UIC in your .TRAN command.

Or force the charge on your capacitors away from equilibrium with  
IC=, and UIC as above.

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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