After hours and hours of getting a simple low pass filter to work, I couldn’t help but share this. With a host of FOSS EDA tools in linux, I really couldn’t resist start using it. I got to credit Ashwith, for the wonderful SPICE tutorials without which my life would have been more miserable. I wouldn’t like to repeat what Ashwith has already written, but I would like to show the schema and results that you can obtain with ngspice as well as matplotlib which are as good as any commercial software that you would use.