Patches that can be applied to plain spice
Other interesting circuit simulators:
- Macquarie Patch Set: A set of patches over spice3f4 that adds the "spec" command, fix MOS6 model and other fixes.
- Spicy sound patch: A really unorthodox but cool (as the author says) patch that allows ngspice to perform transient simulations using sound files as voltage source. It depends on libsndfiles.