Introduction: Arduino UNO Guitar Pedal - Open Hardware.

About: We are MAD about guitar pedals.

pedalSHIELD UNO is an Open Source programmable guitar pedal based in Arduino/Genuino UNO. A platform to start developing your interest in guitar pedals, effects, audio electronics or digital audio.

The aim is to build a guitar pedal with Arduino UNO and easy-to-find components and enjoy creating your own sounds from the first day without deep knowledge in Digital Signal Processing programming or electronics.

You can also share your ideas and sounds in the forum or download the ready-to-use coded effects (like distortion, booster, vibrato, signal-generator, fuzz, delay, tremolo, metronome, etc)

The whole project is Open-Source and Open-Hardware, all the schematics and files are free. The design was also created using KiCAD, an open source/free ECAD, so everybody can contribute.

Step 1: Get the Components.

All the parts where selected trying to find the easiest to source parts, check the complete bill of materials below:


  • C5,C2, C7, C8, C9 6.8n
  • C3, C6, C10 4.7u
  • C1, C11 100n
  • C4 270p


  • R12,R13, R10, R9, R6, R4, R3 4.7K
  • R5, R7, R8, 100K
  • R1, R2 1M
  • R11 1M2


  • RV1 500K
  • D1 Led 3mm blue
  • U1 TL972
  • pdip-8 IC Socket dip 8 socket
  • SW1 3DPT
  • SW2 Toggle switch
  • SW3, SW4 Pushbutton
  • Conn1,2,3,4 1 40 pin header
  • J1, J2 1/4 Jack audio

There is a topic in the forum where you can ask for advice or alternatives.

You can check here a detailed Bill of Materials.

For the PCB you can try to make it in vero-board, use the transfer files to make the PCBs at home or get it in the ElectroSmash website store.

Step 2: Soldering the PCB.

Check the pdf "How to Build pedalSHIELD UNO in 5 Steps". It explains how to mount the PCB step by step with photographs and tips. There is a topic in the forum for any additional questions and a Flickr gallery with high-res photos.

Step 3: Lets Understand the Schematic.

The shield has three parts:

  • The Input Stage: Amplifies and filters the guitar signal making it ready for the Arduino Uno ADC (Analog do Digital Converter).
  • Arduino Board: It takes the digitalized waveform from the ADC and does all the Digital Signal Processing (DSP) creating effects (distortion, fuzz, volume, metronome...).
  • The Output Stage: Once the new waveform is created, the signal is taken from the Arduino digital outputs (two PWMs combined) and prepared to be sent to the next pedal or the guitar amp.

If you want more info, read the complete article or ask in the forum.

Step 4: Start Creating Your Own Effects.

In the forum there is a topic called "How to Start Programming pedalSHIELD UNO". It is a short guide to start coding this arduino uno guitar pedal in 3 steps.

The easiest way to progress is to take the basic examples from the forum, understand and modify them. Just changing some values or parameters can make a great difference.

You can create your own new pedals or mixing some of the examples (vibrato+distortion?). There are a lot of unexplored ideas to be discovered :)