Instruments, not illustrations
An oscilloscope, a Bode plot, a logic analyser, a trace-width calculator. Real tools you operate, drawn live from the numbers you set — not screenshots of somebody else’s bench.
Interactive electronics course
Every idea comes with a control you can move.
A full course in electronics — from what voltage actually is, through op-amps and motor drivers, to a board you can send to a fab. Nothing is explained in words alone: each concept ships with an instrument you drag, and a consequence you see or hear at the same instant.
All of it, free, forever.
Most sites teach you the basics and put the part you actually needed behind a paywall. There is no paid tier here and there is not going to be one. The PCB module — trace width, return paths, impedance, the files a fab needs — is the hardest thing to find written well, and it is on the same open page as the first lesson.
The path
Twelve modules in a strict order: each one uses what the last one built. The numbering is dependency, not decoration.
- 00FundamentalsVoltage, current, resistance and power, the laws that connect them, how to measure them, and where the heat goes. 4 lessons ready
- 01Passive ComponentsResistors, capacitors and inductors as they actually behave — tolerance, ESR, derating, and the specs that bite. being written
- 02Time and FrequencySine waves, RMS and decibels, and the oscilloscope that shows them; then RC and RL transients, filters, Bode plots and resonance — with a filter you can hear. being written
- 03SemiconductorsDiodes, LEDs, BJTs and MOSFETs — switching, driving, and why a slow gate gets hot. being written
- 04Analog ICsOp-amps from the two golden rules to real circuits, feedback, and the 555. being written
- 05Power SuppliesLinear versus switching regulators, ripple, thermal budgets and protection circuits. being written
- 06Digital and the Analog BoundaryLogic levels, pull-ups, level shifting, debouncing, PWM, ADCs and aliasing. being written
- 07Buses and InstrumentsUART, SPI and I²C as they look on a logic analyser — plus how to probe fast bus edges without fooling yourself. being written
- 08Application — SoundMicrophone bias, preamps, active filters, headphone drivers, class D, and where the hum comes from. being written
- 09Application — MotorsH-bridges, stall current, steppers, servos, relays, snubbers and isolation. being written
- 10Application — SensorsThermistors, Wheatstone bridges, instrumentation amps, signal conditioning and noise. being written
- 11From Schematic to PCBFootprints, stackups, trace width, return paths, decoupling, impedance and the files a fab actually needs. being written
How this is built
Schematics you can interrogate
Every circuit is drawn as vector symbols, not a flat image. The text highlights the part it is talking about, current animates along the wires, and the values update as you change them.
Written for someone who can already code
You are not afraid of a formula or a slider, so the pace assumes that. What it does not assume is that you know what a return path is, or why your divider sags.