portotype.com

what it is

This idea is about physical music on a card.

A collectible card with a music album card that actually contains the music. It is not a QR code, URL, streaming token, or ID pointing to music elsewhere.

why

People like vinyl bc it’s a collectible and pretty.

But vinyls are too big and heavy and fragile.

I think this can be replaced with super thin contactless cards the size of football Panini cards or baseball cards.

how it works

We want this to be passive in the sense of no battery or power supply. We also want the music to be stored inside.

The card has:

• Flash storage containing the actual album/audio
• No battery
• No electrical contacts
• No optical code / magnetic stripe
• 13.56 MHz inductive power harvesting — placing the card on/in the player powers it wirelessly
• MCU + BLE radio — currently nRF52840
• 2.4 GHz antenna for transmitting the audio/data to the player
• Target thickness around 0.8 mm

The player has

• two separate jobs: power the card inductively and receive the music wirelessly. The important architectural choice we landed on was that 13.56 MHz is power only; we aren’t trying to squeeze the album through NFC. BLE carries the data.

Diagram

             AUDIO CARD
        63 × 88 mm / ~0.8 mm
┌─────────────────────────────────────┐
│                                     │
│     13.56 MHz inductive coil        │
│   ┌─────────────────────────────┐   │
│   │                             │   │
│   │   Rectifier + reservoir     │   │
│   │          │                  │   │
│   │          ▼                  │   │
│   │     Power regulation        │   │
│   │          │                  │   │
│   │          ▼                  │   │
│   │      nRF52840 MCU ───────┐  │   │
│   │          │               │  │   │
│   │          ▼               ▼  │   │
│   │    128/256 MB        2.4 GHz│   │
│   │     QSPI NOR         antenna│   │
│   │      AUDIO              │   │   │
│   │                         │   │   │
│   └─────────────────────────│───┘   │
└─────────────────────────────│───────┘
                              │
                         BLE data
                              │
                              ▼
                 PLAYER / READER
┌─────────────────────────────────────┐
│                                     │
│ USB-C power                         │
│     │                               │
│     ├──► 13.56 MHz transmitter      │
│     │          │                    │
│     │       POWER                   │
│     │          │                    │
│     │          ▲                    │
│     │       [ CARD ]                │
│     │          │                    │
│     │       BLE AUDIO/DATA          │
│     │          ▼                    │
│     └──► BLE receiver               │
│              │                      │
│              ▼                      │
│        Decode / playback            │
│              │                      │
│              ▼                      │
│          DAC / amplifier            │
│              │                      │
│              ▼                      │
│           SPEAKERS                  │
│                                     │
└─────────────────────────────────────┘