Qucs-S is acircuitsimulationprogram basedon Qucs circuitsimulator. The"S"letterindicatesSPICE. Thepurpose of theQucs-S projectis to use freeSPICE circuitsimulationkernels withthe GUI basedon Qt toolkit.It merges thepower of SPICEand thesimplicity ofthe Qucs GUI.Qucs-S is not asimulator byitself, but itrequires to usean externalsimulationbackend withit. Qucs-Sallows to usethe followingopen-sourcesimulationkernels: Ngspice isrecommended touse. Ngspice ispowe