From: Eric <eriic1@co...>  20111001 07:42:18

On 09/30/2011 03:00 PM, Sam Fentress wrote: > Hi all, > > This is a really simple question I'm sure, but I can't work it out from the > documentation, nor from the examples, all of which have much more > complicated things than I'm trying to do. > > I simply want to create an AC circuit and see the sine wave of the voltage > in the circuit. For example, I'd like to create a simple series AC circuit > with a capacitor and see the sine wave before and after the cap. > > My sample circuit can be seen here: > https://skitch.com/samfentress/fh7s9/qucs0.0.15. I made it a transient > simulation since I understand that's what I want if I want timevarying > results (i.e. a sine wave of voltage over time), and set it to go 0.05 s. > However, when I run "Simulate" it never ends. > > I'm obviously misunderstanding something. All the complicated transient > simulations that I downloaded work fine, so either I haven't set up the > simulation right or my circuit doesn't make sense. > > Any thought? > > Thank you, > Sam > I am new at using QUCS so this may not be the answer you are looking for. I tried your circuit using the default values for the AC source and capacitor. QUCS was having a hard time computing the simulation and it may be because of the frequency of the AC source or the number of calculations required. I adjusted the values of the AC source to have a frequency of 1.0 MHz and changed the capacitor to a value of 1 nF and gave the Transient Analysis a stop time of 1 ms. When I plot the output I use a Cartesian graph graphing Vin.Vt and Vout.Vt. The graph gives good results. If this works, you can play around with the values to see how QUCS is working and hopefully get what you are looking for. Hope this helps you, Eric 