Electrical engineering
Semiconductors
Carriers, diodes, a MOSFET sketch.
Basics
Bands and doping
A semiconductor has a moderate gap. n-type: extra electrons (donors); p-type: holes (acceptors). Intrinsic density is temperature-sensitive. Silicon is standard; compounds serve light and speed.
Devices
A pn diode conducts one way. An LED is recombination light; a solar cell is the reverse. A MOSFET opens a channel with gate voltage — the workhorse of logic and power.
Formulas
Diode equation (sketch)
Ideality n≈1–2. Forward current rises exponentially.
Symbols
-
I_ssaturation current -
nideality factor
MOSFET saturation (ideal)
Long-channel sketch. Real devices add channel-length modulation and velocity saturation.
Symbols
-
V_ththreshold voltage -
W/Lwidth/length
In this field
DC circuits
Ohm, Kirchhoff, series/parallel, power.
Capacitors, inductors, AC
Charge/discharge, reactance, impedance, resonance.
Power, semiconductors, digital
Transformers, three-phase, diodes, gates.
Magnetism, motors, control
Faraday, motors, filters, feedback.
Signals and logic
Fourier sketch, sampling, Boolean algebra.
Measurements and electrical safety
Multimeters, RMS versus peak, transformer ratio, and electrical safety.
Op-amps and filters
The ideal op-amp, inverting and non-inverting gain, RC low- and high-pass, cutoff frequency.
Digital logic
Boolean algebra, gates, flip-flops, and timing.
Three-phase power
Line versus phase, Y and Δ, √3 power, and a motor sketch.
Batteries and photovoltaics
Capacity and C-rate, series/parallel packs, PV I–V curves, and the maximum-power point.