# Working notes

## Teaching preferences

- **No oscilloscope on the bench.** Every transient must be shown via an in-lesson
  simulator or an indirect experiment that a DMM and a pair of eyes can resolve.
  This is the single biggest constraint on lesson design.
- Bench inventory: multimeter, bench PSU, function generator, breadboards, soldering iron.
  Experiments can assume soldering and adjustable supply voltage.
- Charlie can already wire a circuit from a schematic. Skip breadboarding instructions;
  spend the words on *why each part is there*.
- Endpoint is **design from scratch**, so every lesson should end with a number Charlie
  could put on a schematic, not just a concept.

## Interview answers (2026-08-07)

- Driver: motors / solenoids / relays from a microcontroller.
- Level: hobbyist, copies circuits, doesn't derive them.
- Win condition: design from scratch.

## Open questions to ask later

- **Asked at the end of Lesson 02, still outstanding:** the transistor's part number,
  the measured winding resistance of the motor, and whether the motor's 6 V comes from
  the dev board or a separate supply. All three are needed before Lesson 03 can pick
  real parts instead of catalogue ones.
- Any interest in posting to a community for design review — or is this solo? Record
  the answer in `RESOURCES.md`.
- Comfort level with calculus notation. Lesson 0001 introduces `dI/dt` in plain words
  first and only then in symbols; check whether the symbols helped or got in the way.
  *(Asked once, not yet answered — ask again rather than assuming it was fine.)*
- "We" keeps appearing — is Charlie teaching someone else alongside this? If so, lessons
  may need to work as material for two people, not one.

## Note on the mid-turn correction (2026-08-07)

Charlie's question "why one over the other, or never one" revealed a conflation:
transistor and flyback diode treated as competing answers to one problem. This is a
misconception worth watching for — it recurs as "do I still need the diode if I have a
driver chip?" and "is the transistor protecting the pin?". The three-gate frame in
Lesson 02 exists specifically to break it. Do not let later lessons collapse the gates
back into a single "protection" idea.

## Lesson design conventions established

- Shared stylesheet: `assets/lesson.css`. Every lesson and reference sheet links it.
- Reusable components: `assets/quiz.js` (retrieval-practice quiz, immediate feedback),
  `assets/rl-sim.js` (the "Bench Scope" — the instrument this bench lacks).
- Quiz answers are written to equal word counts so formatting leaks no clues.
- Every claim carries a citation to `RESOURCES.md` entries.