W4BRD
David, W4BRD, builds these for PAARC — the Peoria-Area Amateur Radio Club, W9UVI. They started as club program material: rather than explain modulation with static diagrams, they run a real transmitter and receiver in the browser, so you can turn the knobs yourself and hear what changes.
On this site
on a Carrier
CW, AM, SSB and FM in 18 slides, built around the three properties of a carrier you can change. Live canvas waveform and spectrum demos, with speaker notes.
/modulation/presentation Slide deck TransistorAmplifiers
How a switch makes a signal bigger, in 19 slides: bias, gain, classes A to C and the tank circuit, with a live NPN die where you can watch the electrons cross the base.
/amplifiers/presentation Interactive tutor On the AirA complete transmitter and receiver built out of Web Audio. Speak into your mic, pick a mode, and watch it on the scope, spectrum, waterfall and phasor displays.
/modulation/demo