Scanwheel: A DIY Drum-Style Mechanical Television Project

Project Overview

Scanwheel is a build-it-yourself project for a drum-style mechanical television. The device features five side-by-side windows, each utilizing a shared scanning drum but driven by separate LEDs to display distinct images. Each window measures 9mm x 8mm and displays 20 scan lines.

Technical Implementation

The television's software leverages the Raspberry Pi Pico's Programmable I/O (PIO) hardware to control the LEDs. This approach enables high horizontal resolution, which improves image quality beyond what the 20-line vertical resolution might suggest. The design includes a single RGB LED and four white LEDs, balancing wiring complexity with image fidelity.

Required Components

Building the Scanwheel requires several components, including a Symbol Technologies 21-02485 stepper motor, an A4988-based StepStick, a 100uF capacitor, and a Raspberry Pi Pico (any model, with a Pico W recommended for wireless streaming). Specific LEDs and current-limiting resistors are also needed, with resistor values requiring calibration based on the chosen LEDs to match brightness and limit current draw from the Pico's GPIO pins to 50mA.

3D Printed Parts

The project includes 3D models for three printed parts: the base, the drum, and a lid. These models are designed to be scaled during printing to compensate for material shrinkage, with a recommended scale of 100.33% in X and Y for PLA. The drum specifically requires high-quality print settings, such as small layer height and low speeds, to ensure precision in its pinholes.