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In Progress Nova Build Sub-Project

Bluetooth 8-Track Adapter

A custom PCB that fits inside a vintage 8-track cartridge shell, injecting Bluetooth audio directly into the 1973 Nova's factory 8-track player via a magnetic head.

PCB 3D Model

Interactive 3D model of the PCB. Click and drag to rotate, scroll to zoom.

How It Works

The Nova's factory 8-track player reads audio from a magnetic head pressed against the moving tape. This adapter replaces a real tape cartridge — instead of tape, a custom PCB sits inside a 3D printed cartridge shell.

An M18 Bluetooth module receives audio from a phone. A NE5532 op-amp mixes the stereo left and right channels into mono and buffers the signal down to the millivolt level the player expects. That signal feeds into a magnetic head mounted on the shell face, exactly where the original tape would run.

The player's own spring mechanism presses against the head just like it would press against tape — no modifications to the car required. A LiPo battery and TP4056 charging module provide power, with a USB-C port on the shell for charging.

// Signal path
Phone (Bluetooth) → M18 Module → NE5532 Op-Amp (L+R mix) → 1kΩ resistor → 100µF cap → Magnetic Head → 8-Track Player

PCB Specifications

Board

Dimensions 70mm × 45mm
Layers 2 (F.Cu signal + B.Cu GND plane)
Designed In KiCad 10
Manufacturer JLCPCB
Min Track Width 0.25mm signal / 0.5mm power

Audio Circuit

Op-Amp NE5532P (DIP-8)
L+R Mix Resistors 10kΩ × 2
Feedback Resistor 10kΩ
Output Resistor 1kΩ (to head)
Coupling Cap 100µF 35V electrolytic
Bypass Cap 0.1µF ceramic

Power System

Bluetooth Module M18 (15.86mm × 23.54mm)
Charge Module TP4056 with 5V boost
Battery 3.7V LiPo (JST-PH 2mm)
Charging Port USB-C pigtail, panel mount
Power Switch MTS-101 mini toggle (pigtail)

Magnetic Head

Head Element 8.29mm W × 7.13mm D × 6.08mm H
Mount Base Width 24mm total (T-shaped)
Center Section 7mm W × 11.17mm D
Wing Depth 6mm (screw holes in wings)
Base Height 0.49mm
Base Offset Front of base 3.71mm back from head front
Orientation Head element sits ON TOP of base

Shell Cutout Specs

For the 3D designer — required openings in the cartridge shell

Download STEP File
🔌

USB-C Charging Port

  • Hole diameter: 11mm round
  • Anti-rotation tab: 2.05mm W × 0.46mm H
  • Tab position: Bottom of hole
  • Connector type: Round panel mount pigtail
🔘

Power Switch

  • Hole diameter: 6mm round
  • Switch type: MTS-101 mini toggle
  • Mounting: Threaded bushing + nut
  • Clearance behind panel: ~15mm
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Magnetic Head Opening

  • Opening width: ≥ 8.29mm
  • Opening height: ≥ 6.08mm
  • Mount base: T-shaped, 24mm wide
Note for 3D designer: The PCB is 70mm × 45mm. A STEP file of the PCB is available above for exact reference.

Build Status

✅ Completed

  • Circuit designed and tested on breadboard
  • Schematic completed in KiCad 10
  • PCB layout routed (0 DRC errors)
  • Gerbers exported and ordered from JLCPCB
  • STEP/GLB 3D model exported
  • Head placement validated in test cassette

⏳ Remaining

  • Receive PCB from JLCPCB
  • 3D printed shell designed and printed
  • Solder all components
  • Final assembly and testing in Nova

Parts Reference

Key components used in this build — for reference when designing the shell.

🎵

Magnetic Playback Head

Toyvian dual channel stereo cassette magnetic head. Mounts in shell face, contacts 8-track player mechanism.

View on Amazon →
🔌

USB-C Panel Mount Port

Round panel mount USB-C with pigtail wires. 11mm hole, anti-rotation tab on bottom. Mounts in shell wall for charging.

View on Amazon →
🔘

MTS-101 Mini Toggle Switch

SPST ON/OFF mini toggle switch with pigtail wires. Mounts through 6mm round hole with threaded bushing and nut.

View on Amazon →

TP4056 Charge Module

3.7V LiPo charger with integrated 5V boost converter. Solders directly to PCB. Built-in USB-C port not used — external port wires to module pads.

View on Amazon →