Sallen–Key filter – Sample and hold – Sampling (information theory) – Sampling frequency – Satellite radio – Satellite – Saturation (magnetic) – SCADA – Scanner (disambiguation) – Schmitt trigger – Schottky diode – Scott-T transformer – s-domain – SDTV – Segmentation (image processing) – Selenium rectifiers – Selenium – Semiconductor device – Semiconductor fabrication – Semiconductor – Sensor – Serial communication – Series and parallel circuits – SETI – Shaded-pole motor – Shaft voltage – Shielded twisted pair – Short-circuit test – Short circuit – Shunt (electrical) – SI – Siemens & Halske – Siemens (unit) – Siemens – Signal (electrical engineering) – Signal (information theory) – Signal noise – Signal processing – Signal strength – Signal-flow graph – Signal-to-noise ratio – Silicon controlled rectifier – Silicon Valley – Silicon – Silver – Sine wave – Single-phase electric power – Single-phase – Single-sideband modulation – Skin effect – Sliding mode control – Slip ring – Small signal model – Smart grid – Smith chart – Snowy Mountains scheme – Software engineering – Software – Solar cell – Solar energy – Solar micro-inverter – Solar power plants in the Mojave Desert – Solar power – Soldering – Solenoid – Solid state (electronics) – Solid state physics – Solid-state circuit – Sound recording – Space flight – Space vector modulation – Spark spread – Spark-gap transmitter – Spectrum analyzer – Speech processing – SPICE – Split phase – Square wave – Stability theory – Stable polynomial – Stacking factor – Star-mesh transform – State observer – State space representation – Static VAR compensator – Stator – Steady-state – Steam turbine – Steel – Step response – Stepper motor – Stereophonic sound – Stokes' theorem – Storage tube – Stray capacitance – Structure gauge – Structured cabling – Submarine communications cable – Sulfur hexafluoride circuit breaker – Sulfur hexafluoride – Sun Microsystems – Super grid – Supercomputer – Superconducting electric machine – Superconductivity – Superfluid – Superheterodyne receiver – Superposition theorem – Surge arrester – Surge protection – Switch – Switched reluctance motor – Switched-mode power supply – Switchgear – Symbolic circuit analysis – Symmetrical components – Synchro – Synchronization (alternating current) – Synchronous circuit – Synchronous motor – Synchronous rectification – Synchroscope – Syncom – System identification – System on a chip – System on module – Systems analysis –