Project

# Title Team Members TA Documents Sponsor
25 Auto-Guitar Tuner
 Daniel Cho
Ritvik Patnala
Timothy Park
 Eric Tang proposal1.pdf
**Handheld Automatic Guitar Tuner**

**Team Members:**
Timothy Park (twpark2)
Daniel Cho (hc55)
Ritvik Patnala

**Problem:**
When playing guitar, being in tune is essential. When strings are not properly tuned to their correct pitches, the notes played can clash with each other causing what listeners perceive as being "off" or "out of tune." Accurately tuning a guitar is a challenge for both beginners and experienced players. Traditional tuners require the musician to manually turn tuning pegs while reading pitch information, which can be inconsistent and time-consuming. An automatic solution that can both detect pitch and physically adjust the tuning peg would reduce errors, speed up tuning, and improve usability in practice and performance settings.

**Solution:**
We propose a handheld automatic guitar tuner that integrates pitch detection and motorized peg adjustment into one device. The system will capture string vibrations, process them using a microcontroller to identify the current pitch, and automatically rotate the tuning peg with a small motor until the string is in tune. Since the handheld device tunes one string at a time, it can be used on different guitars without needing to worry about different spacing in between pegs and strings. A compact LED screen will display the detected pitch and tuning status, while four buttons (Power, String Select, Mode, Start) provide simple user control. The String Select button allows the user to cycle through the six guitar strings. Each press moves the selection to the next string in order: low E, A, D, G, B, high E, then back to low E again. This circular navigation lets users easily choose which string to tune without confusion or the need for multiple buttons. The Mode button lets users toggle between preset tuning standards (Standard, Drop D, Open G, etc) to accommodate various playing styles and preferences. The design will run on a rechargeable battery, with all subsystems integrated into a custom PCB for portability and reliability.

**Solution Components:**

Subsystem 1: Audio Sensing and Pitch Detection
Purpose: Capture the sound/vibration of the guitar string and convert it to a clean, digitizable signal.
Components:
A transducer (Piezo or electret mic) is used to convert the string vibration to an electrical signal.
If a mic is used, filtering algorithms will be implemented to remove unwanted ambient noise.
Low noise op-amp or preamplification can boost the tiny sensor signal to a usable voltage for the ADC.
Anti-aliasing filter removes any high frequency noise or harmonics above Nyquist so that the sampled form represents real string motion. This can prevent false pitch estimates.
MCU ADC input samples the signal at a steady rate. Clean samples are the raw materials/inputs to the pitch detection algorithm.

Subsystem 2: Microcontroller
Purpose: Run pitch detection algorithms and control the motor
Components:
The microcontroller is used for multiple aspects including streaming the audio in via ADC. It is also used to run the pitch detection algorithm and determine the motor speed/direction to achieve the optimal tuning. Apart from this, it also updates the data on the screen and takes in inputs from the buttons.
GPIO inputs (buttons) can read the users intent including power, mode and string selection, and start/stop. Debouncing will ensure one clean press.
I2C bus for OLED display and fuel gauge: The 2 wire link the MCU uses to communicate with the display to show the note, offset and battery.
Subsystem 3: Motor
Purpose: Physically adjust the guitar tuning peg to reach the correct pitch.
Components:
A DC gear motor provides the mechanism to rotate a guitar’s tuning peg. This needs to ensure that we trade speed for torque so that peg can be turned smoothly and precisely to prevent the string from snapping.
Removable socket attachment allows the tuner to be attached to different peg shapes. A quick swap lets you tune various guitars without redesigning the whole tool.

Subsystem 4: Power Unit
Purpose: Provide stable power to both logic and motor subsystems
Components:
A Li-ion battery will be the primary power source, due to the energy density and rechargeability. Typically specs at 3.7 volts with potential to allow for multiple hours of operations.
Charger IC with USB-C input can be utilized to allow safe and reliable charging of the Li-ion battery.
The Buck regulator will be used to cut voltage levels required by different components (usually 3.3V or 5V).
Fuel gauge

Subsystem 5: User Interface
Purpose: Provide real-time pitch feedback and allow user input
Components:
An OLED display is used to showcase the note/string you want to tune, a cents bar/needle so the user can see whether the string needs to be tightened or loosened. It also shows the battery and the chosen mode.
Four push buttons (Power, Mode, String Select, Start)
Piezo Buzzer to generate beep sounds to signal successful tuning. This would be driven by the microcontroller’s GPIO for tone generation.


**Criterion for Success:**

The device tunes all six guitar strings to within ±12 cents of the target pitch, which is the threshold where most people can perceive a note as out-of-tune. Possibly ±5 cents for further accuracy.
Visual indication (such as an LED) signals when each string reaches its correct pitch.
The tuner should function reliably on both acoustic and electric guitars without causing any damage to the instrument or strings.
Each string should be tuned within a reasonable time frame (under 20 seconds per string).
OLED display refreshes pitch feedback at least 5 times per second

Musical Hand

Ramsey Foote, Thomas MacDonald, Michelle Zhang

Musical Hand

Featured Project

# Musical Hand

Team Members:

- Ramesey Foote (rgfoote2)

- Michelle Zhang (mz32)

- Thomas MacDonald (tcm5)

# Problem

Musical instruments come in all shapes and sizes; however, transporting instruments often involves bulky and heavy cases. Not only can transporting instruments be a hassle, but the initial purchase and maintenance of an instrument can be very expensive. We would like to solve this problem by creating an instrument that is lightweight, compact, and low maintenance.

# Solution

Our project involves a wearable system on the chest and both hands. The left hand will be used to dictate the pitches of three “strings” using relative angles between the palm and fingers. For example, from a flat horizontal hand a small dip in one finger is associated with a low frequency. A greater dip corresponds to a higher frequency pitch. The right hand will modulate the generated sound by adding effects such as vibrato through lateral motion. Finally, the brains of the project will be the central unit, a wearable, chest-mounted subsystem responsible for the audio synthesis and output.

Our solution would provide an instrument that is lightweight and easy to transport. We will be utilizing accelerometers instead of flex sensors to limit wear and tear, which would solve the issue of expensive maintenance typical of more physical synthesis methods.

# Solution Components

The overall solution has three subsystems; a right hand, left hand, and a central unit.

## Subsystem 1 - Left Hand

The left hand subsystem will use four digital accelerometers total: three on the fingers and one on the back of the hand. These sensors will be used to determine the angle between the back of the hand and each of the three fingers (ring, middle, and index) being used for synthesis. Each angle will correspond to an analog signal for pitch with a low frequency corresponding to a completely straight finger and a high frequency corresponding to a completely bent finger. To filter out AC noise, bypass capacitors and possibly resistors will be used when sending the accelerometer signals to the central unit.

## Subsystem 2 - Right Hand

The right subsystem will use one accelerometer to determine the broad movement of the hand. This information will be used to determine how much of a vibrato there is in the output sound. This system will need the accelerometer, bypass capacitors (.1uF), and possibly some resistors if they are needed for the communication scheme used (SPI or I2C).

## Subsystem 3 - Central Unit

The central subsystem utilizes data from the gloves to determine and generate the correct audio. To do this, two microcontrollers from the STM32F3 series will be used. The left and right hand subunits will be connected to the central unit through cabling. One of the microcontrollers will receive information from the sensors on both gloves and use it to calculate the correct frequencies. The other microcontroller uses these frequencies to generate the actual audio. The use of two separate microcontrollers allows for the logic to take longer, accounting for slower human response time, while meeting needs for quicker audio updates. At the output, there will be a second order multiple feedback filter. This will get rid of any switching noise while also allowing us to set a gain. This will be done using an LM358 Op amp along with the necessary resistors and capacitors to generate the filter and gain. This output will then go to an audio jack that will go to a speaker. In addition, bypass capacitors, pull up resistors, pull down resistors, and the necessary programming circuits will be implemented on this board.

# Criterion For Success

The minimum viable product will consist of two wearable gloves and a central unit that will be connected together via cords. The user will be able to adjust three separate notes that will be played simultaneously using the left hand, and will be able to apply a sound effect using the right hand. The output audio should be able to be heard audibly from a speaker.

Project Videos