LTspice IV (from Linear Technologies) is a high performance free Spice III simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators and providing macro models for most of Linear Technology’s switch-mode DC/DC converters, op amps, comparators, linear regulators as well as a library of devices for general analog circuit simulation including discretes. Selected switch-mode DC/DC converters also have demonstration circuit available for free download. There are various demo circuits designed to ensure proper performance and have been reviewed by Linear Technology’s factory applications group. Our enhancements to Spice have made simulating switching regulators extremely fast compared to normal Spice simulators, allowing the user to view waveforms for most switching regulators in just a few minutes. Included in this download are Spice, Macro Models for 80% of Linear Technology's switching regulators, over 200 op amp models, as well as resistors, transistors and MOSFET models. There is only file .exe for Microsoft Windows, but with WINE it works very fine on GNU/Linux. Below images are on distribution GNU/Linux Mandriva 2009.0 and WINE version 1.1.9. If you try it, click here.