1. Automated Guitar String Tuner
BOOM BOOM SSSSSSSSS!
Advisor
Dr. Robert “Rattler” Albright
Industry Representative
Mr. Howard “Hooknose” Voorheis, John Fluke Mfg.
Authors
Ken “Kobra” Aramaki
Kevin “Kopperhead” Atebara
Petra “Python” Carlson
Kevin “Kottonmouth” Vitayaudom
Founder’s Day, 2006
University of Portland School of Engineering

2. Overview Introduction Kopperhead Methods Python/Kottonmouth
Results Kobra
Conclusion Kobra
Demonstration Snake
Founder’s Day, 2006
University of Portland School of Engineering

3. Introduction Project Problem Project Importance Presentation Outcome
THANKS- Dr. Albright, Mr. Voorheis, Rick Severs, Sandy Ressel, Dr. Hoffbeck, Dr. Osterberg, Dr. Lu, Dr. Chamberlain, Matt Phelan & Ian Stokes (mechanical consultant)
Project Problem-Using a closed-loop control system, tune a guitar string to a specified frequency
Project Importance-A true capstone to EE education. Incorporates electrical circuits, electronic circuits, automatic control systems, research
Presentation Outcome-Greater understanding of what a control system is, our project, and the accomplishments reached over the year
Founder’s Day, 2006
University of Portland School of Engineering

4. Methods Research Initial Designs Block Diagram Founder’s Day, 2006
More than half the project was research, calculations, simulations
System Modeling
find/research transfer functions
SIMULINK, bode plots, root locus plots, ruth-hurwitz
Build and test individual sub-circuits
Integrate circuits
Test entire system
Founder’s Day, 2006
University of Portland School of Engineering

5. Block Diagram Founder’s Day, 2006
This is the main circuit. Our subtractor opamp takes in two signals, one from the guitar and the other being the reference voltage. The difference of those two voltages is either positive or negative depending on if the frequency of the guitar is higher or lower than the desired frequency. That difference voltage is what moves our motor. The motor turns the guitar peg in this stage.
The second part is the feedback loop. The low-pass filter, shown here, eliminates the harmonics, leaving the fundamental frequency. This frequency is then converted into a voltage.
The final thing we created was the enable circuit. It ensures that the motor does not turn when the string is not being plucked. When there is a signal from the guitar, the two voltages are allowed to pass through to the subtractor.
Founder’s Day, 2006
University of Portland School of Engineering

6. Methods Cont’d System Modeling Sub-circuits Integration Testing
Transfer Function
MATLAB & SIMULINK simulations
Sub-circuits
Built/tested each circuit separately
Integration
Testing
More than half the project was research, calculations, simulations
System Modeling
find/research transfer functions
SIMULINK, bode plots, root locus plots, ruth-hurwitz
Build and test individual sub-circuits
Integrate circuits
Test entire system
Founder’s Day, 2006
University of Portland School of Engineering

7. Results Final Prototype Accuracy Limitations Improvements
-Simulation results which were created from our resulting transfer function derived from our block diagram. Those three things: our block diagram, transfer function, and simulations were our research results. After we verified that our system was stable we built and tested our device to obtain our finished prototype. Now we’ll look into the block diagram…
-Simulated using MATLAB, we had a very stable system
-Systematically built and tested each individual circuit and integrated
Founder’s Day, 2006
University of Portland School of Engineering

8. Conclusion Introduction Project Explanation Design Details/Results
Founder’s Day, 2006
University of Portland School of Engineering

9. Demonstration Founder’s Day, 2006
University of Portland School of Engineering

10. QuesSsSstionsS? Founder’s Day, 2006
University of Portland School of Engineering