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18. Applications and Implications, Project Development

Tasks:

  • Answer questions based on your final project and progress towards your final progress.

What will it do? - The record player will spin a vinyl record at a precise speed (typically 33⅓ RPM), enabling playback through a tonearm and cartridge that reads the grooves and sends audio signals to an amplifier and speaker. It will have an on/off toggle switch, motor control, and a stable platter.

What will you design? - The plinth (base) to support all components.

  • The platter that holds and spins the record.

  • A custom tonearm, either fixed or pivoting.

  • The motor mount to position the stepper motor.

  • Circuitry and code to control the motor speed with an RP2040 and toggle switch.

What materials and components will be used? - Stepper Motor and ULN2003 driver

  • XIAO RP2040 microcontroller

  • Toggle switch (SPST)

  • Acrylic, MDF, or plywood for the base

  • 3D printed parts for tonearm and motor mount

  • Bearings or smooth rods for tonearm movement

  • Wires, resistors, and capacitors for the circuit

Where will it come from? - Stepper motor and electronics: Amazon, AliExpress, or Fab inventory

  • Wood or acrylic: Fab Lab CNC stock

  • 3D printed parts: Printed at your Fab Lab

  • Tonearm components: Repurposed or bought online

How much will they cost? - Stepper Motor + Driver: ~$5

  • XIAO RP2040: ~$0

  • Toggle Switch: ~$4

  • Materials (wood): ~$5–$10

  • Cartridge + amplifier: ~$15–$30

What parts and systems will be made? - Mechanical base and platter

  • Stepper motor system with speed control

  • Circuit board for motor + switch

  • Tonearm and possibly audio system

  • Enclosure or housing

What processes will be used? - 3D printing

  • CNC milling

  • Laser cutting

  • Soldering and electronics assembly

  • Programming the RP2040 in Arduino IDE

What questions need to be answered? - Will the tonearm track the record correctly and not skip?

  • Can the RP2040 maintain consistent torque at the correct RPM?

  • How to calibrate the stepper motor to rotate at exactly 33⅓ RPM?

How will it be evaluated? - Does it spin at the correct and stable RPM?

  • Does the toggle switch reliably control the system?

  • Is the design mechanically stable and well-constructed?

  • Can it play sound properly if a cartridge is installed?

What tasks have been completed? - Motor has been wired and tested with RP2040 - Toggle switch logic and on/off control completed - Initial code written to control motor speed - Testing at different RPMs done

What tasks remain? - Final motor RPM calibration

  • Full assembly of platter and base

  • 3D printing tonearm or motor mounts

  • Wiring everything neatly into an enclosure

What has worked? What hasn’t?

Worked: - On/off toggle switch functionality - Uploading and modifying code on the RP2040 - Stepper motor control at lower RPMs

Hasn’t Worked: - Consistent spinning at exactly 33⅓ RPM - USB cable issues caused serial monitor errors - Some motors stall or vibrate at higher RPM

What questions need to be resolved? - Can a different motor spin more accurately?

  • Should a belt drive be used for smoother motion?

  • What’s the best material for the platter to reduce vibration?

What have you learned? - How to integrate mechanical and electronic systems.

  • How to control and calibrate a stepper motor using an RP2040.

Bill of material

Last update: June 4, 2025