w5isp.com/IDEAS.md

Future interactive post ideas

Working scratch list. Same format as the NLOS post: vanilla JS, 2D canvas, scenes scoped to a single post via <link> and <script> tags in the markdown. Each idea is a candidate; most of these are one-post-sized if focused.

Electronics

• How a transistor actually amplifies. Draggable base current / gate voltage on a NMOS or NPN schematic, live I-V curve on the side, carrier flow animation in the channel or base region. Payoff: "small signal gain" stops being a formula and becomes something you can see.
• LC resonance from scratch. Tank circuit with sliders for L, C, and drive frequency. Show the phasors rotating, impedance magnitude/phase sweeping, and a scope trace of voltage vs current. Payoff scene: pumping the tank at resonance and watching it ring.
• An oscillator starting up. Colpitts or similar. Start from noise, show the limit cycle forming, let the reader nudge the loop gain and see it either die off or run away.
• Feedback loop stability. Drag the poles and zeros around on the s-plane, watch the step response and the bode plot change. The moment a pole crosses into the right half plane and everything goes sideways.
• A superhet receiver, piece by piece. Antenna, RF amp, mixer, LO, IF filter, detector. Tunable signals scrolling through the spectrum, user drags the LO, watches the desired signal slide into the IF passband. Image rejection as a visible thing.
• A switching power supply. Buck converter with a slider for duty cycle. Inductor current ramping and freewheeling, output ripple. Makes the "magic efficiency" of SMPS feel earned.
• Noise figure, cascaded. Build a receiver chain by dragging in blocks (LNA, mixer, IF amp), each with a noise figure. Live link budget at the bottom. The Friis formula stops feeling abstract.

Computers / networking

• A TCP connection, from the packets' perspective. Client on the left, server on the right, sequence numbers and window sizes visible, user can introduce loss or latency and watch congestion control react. Slow start, fast recovery, the window collapsing on a single dropped packet.
• How DNS actually resolves a name. Recursive resolver, root, TLD, authoritative, caching. User types a hostname, watches the queries fan out with their TTLs.
• What a CPU does per cycle. A tiny toy ISA executing step by step. Pipeline stages, hazards, stalls. Adds a register renamer in a second scene and you get a decent intuition for why modern CPUs are fast.
• Cache coherence (MESI). Two cores, a shared line of memory, user issues reads and writes, arrows show the invalidations flying around. The reason your "obviously correct" lock-free code isn't is usually on this graph somewhere.
• BGP finds a route. A handful of ASes with peering relationships, user picks source and destination, watches announcements propagate and the path emerge. Bonus scene: a single misconfigured announcement leaking and causing a global outage.
• Virtual memory and page tables. Process issues a virtual address, the MMU walks the levels, TLB hits and misses, page fault handling. Good payoff if tied to a real program's memory map.

Ham radio

• SSB, from audio to RF. Mic input on the left, phasing or filter method in the middle, RF out on the right. Show the audio spectrum, then the DSB-SC product, then USB after filtering or phasing. Bonus: demodulate it back on the receive side with a BFO offset and watch Donald Duck.
• FT8 end to end. 77 bits of payload, LDPC encoding, Costas sync, GFSK shaping, Gaussian noise, decoder pulling it back out under the noise floor. The part where you add enough AWGN to make the signal invisible and the decoder still pulls it is the Adams moment.
• An SDR front end. Antenna, bandpass, mixer with quadrature LO, anti-alias, ADC, decimation filters. User chooses the tuning frequency and the SDR slides through the spectrum.
• Great circle and grid square math. Enter two grid squares, get the path, bearing, distance. Drag either endpoint on a globe. Small but useful.
• HF skip vs MUF. Ionospheric layers with time-of-day and solar-cycle sliders. Rays launching at various angles, reflecting (or punching through) D/E/F layers, landing somewhere else on the globe. Great contrast piece to the NLOS post.
• Feedline loss as a function of length, frequency, and type. Slider for length, buttons for RG-58/RG-8/LMR-400/heliax. A visible chunk of transmit power disappearing into the coax as frequency climbs.

Microwave / advanced RF

• Rain scatter. A rain cell, two stations not in LOS, common volume in the cell. Slider for rain rate, frequency. Show how a signal bounces off the precipitation and arrives from a totally wrong direction. Natural follow-up to the NLOS post.
• Meteor scatter. A meteor streaking through the ionosphere leaving a plasma trail, signal reflecting during the brief window. Ping lengths, burst rates. An argument for why 6 meters is worth owning a rig for.
• EME (moonbounce). Lunar geometry, path length, Doppler spread from libration, degree of polarization rotation from Faraday. Answer to "why do I need a big dish for this" becomes visually obvious.
• Phased array beam steering. Array of elements, user slides the phase taper, the beam sweeps. Grating lobes appear if spacing is too wide. Explains why Starlink and every modern radar system looks the way it does.
• Smith chart, but friendly. Drag a load impedance, watch reflection coefficient, SWR, and return loss update. Add a matching network with an L-network or stub and watch it slide to the center.
• Parabolic dish aperture. Slider for diameter and frequency, see gain vs beamwidth vs sidelobes. Illumination taper as a second control, showing the efficiency / sidelobe trade.
• ITU-R P.838 rain attenuation. Pick a frequency, a rain rate, and a path length. Curve of attenuation over the full microwave band. Useful companion to anything on 10 GHz and up.

Longer arcs

A couple of ideas that would be a whole series, not one post.

• "Build a receiver from first principles." Start at an antenna picking up an EM wave, end at a speaker playing audio. Every stage a scene. Takes the shape of a short book.
• "What the atmosphere is doing right now." Live data from prop.w5isp.com, rendered as an interactive cross-section of North Texas atmosphere at the current hour. Refractivity aloft, ducts forming and collapsing, paths scored against real conditions. Operational rather than explanatory.
• "Every component in my station, demystified." One post per piece of gear. Transverter, PA, sequencer, rotator, preamp. Each one a scene that makes the internal thing you pay for make sense.

House style

Keep each post focused, one topic, deep. No survey posts. Interactive bits earn the page weight, static bits carry the prose load. No em-dashes. Adams when it fits, silence when it doesn't.