Loaf

(WIP)

Loaf

(WIP)

Overview

The Loaf is a compact testbed specifically created for testing and prototyping digital effects.

Centered around a breadboard, this testbed features:

  • 2 independent input/outputs
  • 2 3PDT bypass switches
  • 8 potentiometers
  • 3 SPDT switches.

The abundance of controls makes this testbed perfect for pretty much any digital effect you may want to design!

Proposed Design

The Concept

  • A compact 3D printed guitar pedal testbed designed for prototyping and testing digital effects
  • Built around the Daisy Seed microprocessor, chosen for its audio capability, low cost, and small size
  • Designed to be portable for travelling between home and university

Enclosure & Physical Design

  • Fully designed from scratch in Fusion360, to be 3D printed
  • Front panel: 2 input jacks and 2 output jacks
  • Back panel: DC power jack, power switch, LED power indicators, USB/general cable grommet, and ample ventilation

Top Panel Layout

  • 8 potentiometers across the top row for effects control
  • 2 × 3PDT footswitches on the left, one per channel for true bypass control, each with an LED status indicator
  • 3 × SPDT toggle switches on the right for effects control
  • Central breadboard cutout, modular, swap in/out Daisy Seed & components as needed

Signal Routing & Bypass

  • When engaged: Input → Signal Conditioning → Daisy Seed → DC Blocking Failsafe → Output
    • ~500 kΩ input impedance
    • <400 Ω output impedance
  • When bypassed: Input → Output (True bypass)
    • LED indicators disconnect when bypassed

Input Signal Conditioning

  • Typical guitar output is not adequately suited for direct ADC
  • Input signal amplified by 5x to improve sampling quality
  • Daisy Seed audio inputs range from -1.8 V → +1.8 V
    • Typical single coil pickup voltage is ~100 mV
    • Amplification results in an amplitude of ~500 mV
    • Centered around 0 VDC, this amplified signal is well within the boundaries of the Daisy Seed audio input specs

Power Supply Design

  • Source: 9 VDC (standard guitar pedal supply)
    • Daisy Seed input supply voltage: 5 VDC → 17 VDC
  • 9 V to 3.3 V via LDO linear regulator
    • Stable reference voltage for the potentiometers and switches
  • Features several quick connect breakout points for ease of assembly and futureproofing
  • UI consists of a DC input jack (9 VDC), an on/off switch, and LED power indicators

PCB Design

  • PCB mounted using the 8 potentiometers, 3 SPDT switches, and 4 in/output jacks
    • Includes several supporting stages such as current limiting resistors and pulldown capacitors for the potentiometer outputs
  • Contains PSU circuit with several breakouts for all three voltages
    • 9 VDC, 3 VDC, and GND (0 VDC)
  • Includes various quick-connect breakouts for breadboard & Daisy Seed supplies, ribbon cables for peripherals, various in/outputs, etc…

3D Printing

  • 3mf file provided
  • Layer height: 0.16 mm
  • Infill: 20%
  • Walls/Ceilings/Floors: 3
  • Supports: Snug supports enabled
  • Fuzzy skin (optional): Enabled on outer walls of both body and bottom

(Work In Progress)

Misc. Progress Pics

License & Usage

This project is shared freely for personal, educational, and non-commercial use. You are more than welcome to use, modify, and build upon my designs, just please give due credit.

All designs are copyright of Kyle Zink. Personal, non-commercial use and construction is permitted. Redistribution, resale, or commercial manufacture of designs and/or derivatives thereof is strictly prohibited without explicit written permission.