This page contains links to ngspice applications or short paragraphs describing the usage of ngspice. Its content will grow over time. You are welcome to contribute!
Christophe Basso's book Switch-Mode Power Supplies is a very well done source for understanding and practically designing power supplies using SPICE simulations.
ngspice input files are offered here for download. They correspond to circuits described in the book, often 1:1 for specific figures. Files for chapter 1 are now available. More chapters to follow!