6
Electronics at the Table
Light, haptic, sound — never a rules engine
The Arcane Wand is a magical physical flourish with an ordinary manual fallback. Architecture: rechargeable handheld plus removable powered board-effect module. Communication: ESP-NOW between two ESP32-C3 devices. Board reaction: a microservo rotates a mechanically captive magnet beneath a steel-washer relic token. Aiming light: shrouded narrow-beam red or amber LED. No laser in V0.1. No phone, router, AI, or autonomous rules logic. BLE later.
Three signature beats
- Light + haptic + sound feedback.
- Magnetic board-token or relic interaction.
- Aiming / pointer behavior using the safer shrouded LED baseline.
Acceptance
| Test | Bar |
|---|---|
| Reliability | 20 consecutive cycles with no jam, reset, or missed command. |
| Feel | Three observers rate “the table feels magical” at least 4/5. |
| Latency | Feedback begins ≤150 ms; board reaction begins ≤500 ms and completes ≤2 s. |
| Runtime | 90 minutes. |
Cost and exclusions
Estimated BOM $104.13 before shipping/tax; realistic $95–$130; reuse may reduce to $70–$90. V0.1 safety: protected LiPo, supervised charging, separate 5V servo supply, and a captive magnet; no loose high-strength magnet or laser. RFID/NFC, multiple mechanisms, and CoreXY remain future experiments.
Home build, stripped
| Part | Job | Notes |
|---|---|---|
| ESP32-C3 SuperMini ×2 | Wand + board talk ESP-NOW | No router. Pair them once. |
| Shrouded 5 mm amber LED | Aiming / Reveal pointer | Heat-shrink a tube. Not a laser. |
| Coin haptic or ERM motor | Hit confirmation | A 100 ms pulse is enough. |
| Passive buzzer | Second channel of feedback | One tone. Not a soundtrack. |
| SG90 microservo | Turns the captive magnet | 5 V separate from the radio. |
| Steel washer relic token | The thing that moves | Sits on the board, not in a pocket. |
| TP4056 + protected 3.7 V LiPo | Wand power | Charge off-table, watched. |
| 365 nm UV LED (optional) | Reveal window | 30 seconds. Manual UV torch is legal. |