I have been using circuit simulators for the past 11 years as a power electronics researcher and after using a large number of them, found that for simulating large nonlinear circuits, quite often all of them run into specific issues. So I began this project of developing an open source circuit simulator using Python in December 2012 with my blog: http://pythonpowerelectronics.blogspot.ca/

The main objective of the simulator is to solve a few major problems that most simulators run into: 1. Computational overhead - While simulating large circuits for large time intervals, most simulators consume a large portion of the memory and processor which makes the computer either hang or unusable for other activities while the simulation is in progress. 2. While simulating circuits that are interconnected, the resultant system become "stiff" and that means they have extremely low time constants. Many simulators are unable to simulate stiff systems and sometimes either crash or quit. 3. In a circuit with controllable elements such as switches, the user would like to include code that would be as close as possible to the actual code embedded in a microcontroller. Most circuit simulators provide compilers and builders to convert control code to compatible formats for hardware implementation. However, the user still does not have complete freedom to write code as they would like.

I have been able to produce a basic circuit simulator and have released a project on SourceForge: http://sourceforge.net/projects/pythonpowerelec/