LTspice IV is a high performance Spice III simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators.
Integrated schematic editor and simulator. Dynamic analysis updates waveforms and curves as you edit Native digital simulator Worst Case analysis to find the statistical and extreme limits of performance Smoke Analysis to assess how close the circuit is to violating maximum opera.
Circuit Solver is an electronic circuit simulator. You drag your electrical components and place them on one at a time. You hook up some sources and you place some meters to read the values.