Final Project¶
Here is video for my final project
A Personal Journey¶
The world is changing fast, often in ways we don’t expect. I began FabAcademy in 2023 with a lot of energy and motivation, but life led me to pause and reflect for a while.
In 2025, I came back with renewed focus and determination to complete the journey. This project reflects not only my technical growth but also my personal development over that time.
Idea¶
Music has always been a meaningful part of my life. Building a guitar tuner felt like the perfect way to combine my passion for music with my growing skills in electronics and programming. I wanted to create something practical that musicians could use anywhere, without relying on smartphones or expensive gear.”
Project Management¶
To stay organized and efficient, I created a timetable to track my progress. Here’s how I planned my work:
| Task | May 6–12 | May 13–19 | May 20–26 | May 27–Jun 2 | Jun 3–9 | Jun 10–13 |
|---|---|---|---|---|---|---|
| Research | ████████ | |||||
| OLED + Pico setup | ████████ | |||||
| Signal proc. testing | ███████ | |||||
| PCB design & prod. | ███████ | |||||
| Assembly & soldering | ███████ | |||||
| Firmware | ███████ | ███ | ||||
| Troubleshooting | ███████ | |||||
| Real guitar testing | ███████ | |||||
| Documentation | █████ | |||||
| Integration | ████ | |||||
| Case design (opt.) | ██ | |||||
| Final pres. prep | ██ | ███ |
Research¶
I started by deciding which components to use.
Digital Signal Processing (DSP) isn’t commonly done on microcontroller boards because specialized chips handle it more efficiently. But I wanted to create a tuner that works directly on a microcontroller, processing guitar vibrations in real-time.
Many DSP-capable boards use ST microcontrollers with the CMSIS library. Unfortunately, these development boards are usually too large to mount on a guitar.
Electronics¶
To capture the guitar’s vibrations, I used a piezoelectric sensor. The signal from the piezo is very weak (around ±100mV), so I designed an amplifier circuit to boost the signal to a readable level for the microcontroller.
You can find a detailed explanation of the amplifier circuit on my Electronics Production Week Page.
Next, I designed a PCB that includes the Raspberry Pi Pico 2W, OLED display (to show the string name and tuning info), the amplifier circuit, and a voltage regulator to power everything from a battery. This board is also described on the same page.
DSP¶
I chose the Raspberry Pi Pico 2W for its processing power.
There’s a library called ulab designed for DSP on the Pico, but I faced some issues integrating it, so I decided to implement the FFT algorithm myself without extra libraries.
I explain the code and its working in detail on my Input Devices Week Page.
It took a lot of trial and error to find the right signal processing parameters, but finally, I started getting accurate results.
OLED¶
I wrote a simple program to display data on the OLED.
Then I combined the OLED and DSP code to display the detected string and tuning status in real-time.
More about the OLED code can be found on my Output Devices Week Page.
System Integration¶
Once the system worked well while connected to my PC, I started integrating it with a real guitar. This involved three steps:
I described all steps of system integration at my System Integration week page.
1. Program¶
Unlike Arduino IDE, Thonny IDE doesn’t automatically save programs to the board. To make the device run standalone, I saved my program as main.py directly on the Raspberry Pi Pico.
2. Power¶
To make the tuner autonomous, I powered it with a 9V battery connected to a 5V linear voltage regulator, providing stable power to the microcontroller.
I also added a switch to turn the device on and off.
3. Case¶
I designed and 3D-printed a case for the device, including separate covers for the PCB and OLED.
The OLED cover was laser-cut from acrylic for a clean finish.
Final View¶
Back View
Front View
Bill of Materials (BOM) and Cost¶
| Item | Source | Cost |
|---|---|---|
| Raspberry Pi Pico 2W | Gift from a friend | $0 |
| OLED Display (128x64 SPI) | AliExpress | ~$3 |
| OPA2340 Op-Amp | Local electronics shop | ~$2 |
| Passive components (R, C) | From lab stock | ~$1 |
| Piezo Disk | From FabLab | $0 |
| PCB material | FabLab (internal use) | ~$1 |
| DRV8825 drivers (x6) | AliExpress | ~$9 |
| Stepper motors | Recycled from DVD drives | $0 |
| Total (used parts) | ~$7 | |
| Total spent (including unused parts) | ~$16 |
Note: DRV8825 and stepper motors were for the original auto-tuning idea, but not used in the final version.
Evaluation¶
I tested the tuner on all six guitar strings, comparing the detected frequencies with standard tuning apps. The pitch detection was generally accurate with minor deviations of just a few cents.
Early on, the amplifier circuit produced some noise, which I reduced by adjusting components and adding shielding. The 3D-printed case needed a few redesigns to fit properly and be user-friendly.
Latency was low enough to provide real-time feedback, making the tuner practical for everyday use.
Overall, the device met its goals: it is standalone, portable, and accurate enough for casual and semi-professional guitar tuning.
Reflection and Implications¶
This project was not only a technical challenge but also an opportunity to grow personally and professionally. FabAcademy has given me the confidence to bring together design, electronics, and programming into a meaningful, working device.
For a more in-depth reflection on the broader applications and implications of this work, see my Applications & Implications Week Page.
Conclusion¶
This project has been a great learning experience. I enjoyed the process of capturing and amplifying signals, and working through the complexities of digital signal processing. I’m proud to have created a fully standalone guitar tuner that integrates hardware and software seamlessly.
Future Development¶
This is just the beginning.
My next goal is to add small motors to physically adjust the guitar’s tuning pegs, creating a fully automated guitar tuning system that listens, thinks, and tunes itself—letting musicians focus solely on playing.
More broadly, this project marks the start of my journey into audio technology.
Music has always been my passion. Together with my friend Yervand, a sound engineer currently studying in Ireland, we plan to launch a startup focused on innovative audio equipment—tools designed for musicians, creators, and learners.
This tuner is my proof of concept.
The future? High-quality, human-centered audio gear, designed and built from scratch—right here in Armenia and beyond.
Thank you!!¶
I would like to sincerely thank the entire FabLab Dilijan community and my instructors for their continuous support and encouragement throughout this project. Special thanks to my friends Norayr and Andranik — Norayr for generously lending me his guitar, and Andranik for his invaluable help and guidance every step of the way. Your support made this journey possible.
Files¶
Here is the full zip file containing all the files used in this project.