Guitar Tuner EET 2278 Capstone Project Tyler Davis Sinclair Community College EET 2278 Spring 2016 Professor Russo
2 Table of Contents ACKNOWLEDGEMENTS... 3 ABSTRACT... 4 INTRODUCTION... 5 PRINCIPLES OF DESIGN... 6 DESIGN DETAILS... 7 CONSTRUCTION... 9 TESTING, TROUBLESHOOTING, AND CALIBRATION... 11 OPERATION... 13 CONCLUSION... 14 RECOMMENDATIONS... 15 BIBLIOGRAPHY... 16 ADDENDA... 17 SPEC SHEET... 17 PARTS/PRICE LIST... 18 Project Proposal Journal Summary Presentation slides Project Report Guidance and Requirements Handout
3 Acknowledgements These are the people that helped me with my project for EET 2278: Professor William Russo. Approved my project and was there to answer my questions. Professor Abdullah Johnson. Gave me information on micro controller boards. James Thorstenson. Helped explain the type of op amp I needed in my project Condy Davis. Assisted with the fabrication of the case. Irv Rutherford. Assisted with the programing of the Arduino
4 Abstract This report will detail my EET 2278 Capstone Project, a guitar tuner. The guitar tuner was design to use an Arduino Uno to detect a signal from the guitar and using a LED display assist the user in tuning the guitar. The user will need to connect the guitar to the tuner using an audio cable that plugs into the side of the tuner. Each strum of a guitar string sends a signal to an amplifier circuit then, then to the Arduino, and finally to the LED display. The LED display will change in real time as the user adjust the tuner knobs on the guitar that is being tuned. The user will know when the string is in tune when the green LED lights up on the display.
5 Introduction Before I started in The EET Program at Sinclair Community College I loved music, specifically playing guitar. I played in a garage band in high and didn t have a nice guitar. My guitar would always be out of tune and I would have to tune it after every song I played. I became really familiar with how a guitar is supposed to sound. I never thought about how a guitar tuner actually worked. When I was told that I needed to come up with a project for EET 2278 Capstone I thought that a guitar tuner would be perfect. I researched how a guitar tuner works and I knew that I wanted to make one. I set out to make a guitar tuner that would detect the frequency of a guitar string and tell if it is in tune. Once I determined that I was going to go ahead a make a tuner for my project I started to research how I would make it. I found that someone have used an Arduino Uno as a Frequency Detector online and that gave me an idea to use it in a guitar tuner. I knew that this tuner would use a microcontroller to measure the frequency of an input audio signal and determine what string the user is strumming and if the note is sharp or flat. Once that has been determined it will light up an LED to identify the string and another LED or identify the pitch of the note. That is how I came up with this project.
6 Principles of Design We I started to design this guitar tuner I had to think about how I was going to use the Arduino Uno to detect the frequency of the strum of a guitar string. I knew that the audio signal was going to be too small for the Arduino to read. The audio signal coming from the electric guitar needed to be amplified to be about 5V peak to peak and offset to be centered around 2.5V as opposed to 0V. The signal needed to be between 0 and 5V in order for it to be read by the Arduino's analog pin. It also need to have the greatest amplitude possible without clipping in order to get more accurate frequency calculations. Using a TL082CP I would fabricate an amplifier for the audio signal to go to the Arduino. I know how a in tune guitar sounds however, for the program I needed to make for the Arduino, I had to know what was the in tune frequency for each string. I found for each string the in tune frequency is as follows: E - 82.4 Hz, A - 110 Hz, D - 146.8 Hz, G - 196 Hz, B - 246.9 Hz, and hie - 329.6 Hz. Since the higher strings have a much lower amplitude signal than the lower strings, it can be tricky to get the frequency detection to work. My code has a variable called ampthreshold that is the minimum signal amplitude for the Arduino to calculate frequency. For the guitar tuner, the ampthreshold should be high enough that the Arduino calculates the frequency of the higher strings, but also low enough that it does not pick up too much noise from the lower strings. I found that an ampthreshold of 20 works. You have to strum the high strings a bit harder to get the Arduino to pick them up, but the frequency detection works well.
7 Design Details Audio Signal Audio Input (1/4 Audio Jack) UA1 (Op-Amp Circuit) Amplifies the signal to 5V peak to peak and offset to be centered 2.5V Pitch LED Display HB1 (Arduino Uno) Detects the frequency of the signal. Calculates the note and pitch of the string String LED Display
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9 Construction This project required a lot of planning in order to get the build completed. I knew that I wanted to use an Arduino to make the tuner. I had to design, order part, prototype, solder, troubleshoot, and finalize the build for the guitar tuner. This project required me to use everything that I have learned throughout my EET career. The First thing I had to do for this project was design a circuit that I could use for the guitar tuner. I used an electronic schematic capture and simulation program called Multisim to design my circuit. I also drew on paper how I wanted the LED display to look like. I also researched the Arduino to see if you could program it to detect frequency. Once the circuit was designed, the program researched and I knew what components I needed, I ordered the components and started working on the program for the Arduino. Once the components arrived I tested each one to make sure that they were up to spec. With all of the components in hand I was able to Prototype my circuits. I built my circuits on bread boards so I could test them and troubleshoot for bugs. I made an amplifier circuit and a LED circuit on bread boards, making sure that the LEDs were laid out how I wanted. I programmed the Arduino with my frequency detection program and plugged it into my prototype circuits. I used a frequency generator to simulate the signal going into my prototype. Once I was satisfied with my results of the test I started to solder my components on to circuit boards. Once everything was soldered, I made an enclosure for my project. This required me to drill holes for my LEDs, a Power switch, an audio
10 jack, and holes to mount my boards. I mounted all the parts into the case and made sure that everything was secured to the case. With everything in the case I made an overlay that went over the faceplate of my tuner to indicate what the LEDs mean. The figure below is the overlay I have made for the faceplate. The overlay designates the pitch and the note of the string. That was the construction of my Project. This line of LEDs show whether the string is Sharp or Flat. There is a green LED in the center to indicate the perfect pitch. This line of LEDs shows what string is being strummed.
11 Testing, Troubleshooting, and Calibration Every project requires some testing, troubleshooting and calibration to function properly. My project was no exception, I had to do all of these while constructing my project. I had to make sure that my circuits worked properly, troubleshoot and fix a problem, and calibrate my program. As I built my prototype and final build of my project I had to do a lot of testing for my tuner. I used a variety of electronic test equipment including, a multi-meter to check component and continuity, function generator to simulate the audio signals, and an oscilloscope to verify that the signal was being amplified. I even used my own guitar to test my final build of the project. I had to troubleshoot one problem during the final build of my project. My circuit wasn t functioning properly because the Arduino wasn t responding to my input. So the LED display won t change no matter what string was strummed. I traced along my signal wire to each of the points of contact to make sure that there was continuity between points. I found the problem very quickly with this method. I didn t solder one of the pins on my op amp. So the signal was not being amplified and the Arduino could read the signal coming in. So after I soldered that joint, I tested the tuner again with my guitar and the LED display changed with every strum of the guitar string. Once my project was working properly I have to calibrate it to insure that pitch of each note was as close to the perfect as I could get to using the Arduino. I used a tuner
12 that I have used for years to tune my guitar to standard E tuning. Once the guitar was tuned using the professional tuner I compared my project to the professional tuner. Remarkably, my project tuner was very close in terms of pitch. I just had to go into the program of my Arduino and adjust the frequency of the strings only 1 Hz up from what I programed. After making this adjustment I tuned my guitar again using both tuners that the different was unnoticeable.
13 Operation This guitar tuner is very easy to use for tuning a guitar to standard E tuning. The required materials to use this tuner are an electric guitar, a ¼ audio cable, and the tuner. First you will plug one end of your audio cable into your guitar and the other into the tuner. Make sure that the guitar is turned up to the maximum volume to insure the signal will be read by the tuner. Turn on the tuner and wait for the LEDs to stop flashing. Once that is done pluck the open string you wish to tune. Guitars have six strings that count from the bottom up, so the thinnest string is your first string (an E) and the thickest string is your sixth string (also an E). The strings, in order from first to sixth, should be tuned to the following notes: e (thinnest string), B, G, D, A, & E (thickest string). Follow a string all the way up the neck to find its associated tuning peg. Pluck the string and turn the tuning peg to make the pitch go up (clockwise) or force it to go down (counterclockwise). Turn each peg smoothly and slowly, getting used to applying constant pressure in both directions. The LEDs on the tuner will change as you tune your guitar indicating what string is being plucked and if the string is high or low. Turn the peg of your guitar until the green LED on the tuner lights up. Repeat for each string until all of the strings are in tune.
14 Conclusion That is my Capstone project for EET 2278 for the spring of 2016. I had to use everything that I have ever learned or covered during the duration of this project. I even had to develop some new skills and learn new concept to fully complete my project. I feel very proud of what I was able to achieve with the time I had. I learned about how to properly use test equipment, I learned how to program a microcontroller, and I also learned steps on how to troubleshoot. I am disappointed with how my overlay turned out, it is made from paper and I just don t feel very satisfied with how it looks. I wish I made an actual face plate made from plastic. All in all I feel very satisfied with how my project turned out and I am happy with my experience in the EET Program here at Sinclair Community College.
15 Recommendations If I was to do it again I would change the design a bit. I would add a way to bypass the tuner and have another audio jack that would plug into an amp so once the guitar was tune you could go right to playing your guitar. If someone else wanted to make the guitar tuner I would have a few suggestions for them. Number one is MANAGE YOUR TIME, Time is going to make or break you during this project and good management is the difference between finishing with a project you are confident in and a project that just works. Another tip if someone is going to use an Arduino is to use the forums on Arduino s site to help with the programing if you are struggling. Finally the last tip I would suggest is try not to stress out over the project. Don t keep hitting the brick wall with your head, take breaks and get your work done at your own pace.
16 Bibliography "Arduino Forum - Index." Arduino Forum - Index. N.p., n.d. Web. 15 Apr. 2016. "How to Tune a Guitar." WikiHow. N.p., n.d. Web. 15 Apr. 2016. Ghassaei, Amanda. "Arduino Frequency Detection." Instructables.com. N.p., n.d. Web. 15 Apr. 2016. "Guitar Strings." Guitar Strings. N.p., n.d. Web. 15 Apr. 2016.
17 Addenda Spec sheet TYLER DAVIS SECTION # 100_ DATE 4/15/16 Guitar Tuner Specifications Specifications Voltage 18v Current 5ma Resistance 100K Ohms Power Rating 1 Watts Frequency 70Hz-350Hz Range Length Height Width Weight Dimensions 7.5in 4.5in 2.2in 3lbs Inputs and Outputs Audio Signal 1/4in audio female plug Input Interface 5mm LEDs Controls SPST(ON/OFF Switch) General Description: This is a battery operated Guitar tuner using an Arduino Uno microcontroller board. This Tuner can help a user tune an Electric Guitar to Standard EADGBE Tuning. Using Frequency detection to determine the right pitch of the note for each string of the guitar, the tuner will tell the user if the string is sharp or flat. The LEDs indicate what the user must do in order to tune their guitar. Technical Information Controller Card Arduino Uno Rev 3 Power Supply Energizer 9V Battery Operating 0 F-100 Temperatures
18 Parts/Price list EET 2278 Spring, 2016 PROJECT NAME: Guitar Tuner DATE: 4/15/2016 Project Manager Name: TYLER DAVIS Cost Extended Qty Descriptor Description Each Cost Procured from 1 Arduino UNO R3 Programable micro controller $21.47 $21.47 Amazon.com 1 1/4-Inch audio Jack Female plug for audio cable $1.55 $1.55 Amazon.com 1 Arduino UNO R3 Case Protective case for Arduino $9.99 $9.99 Amazon.com 1 150 Ohm Resister 100pc pack of Resistors $4.99 $4.99 Amazon.com 1 22k Resisters 10pc pack of Resistors $4.77 $4.77 Amazon.com 1 10uf Capacitors 10pc pack of Caps $4.29 $4.29 Amazon.com 1 9v Snap Connectors 5pc pack $8.09 $8.09 Amazon.com 1 Wall Adapter Power Supply 9V DC 650mA used to plug Arduino to a wall outlet $5.49 $5.49 Amazon.com 2 TL082CP TI Operational Amplifiers - Op Amps $0.77 $1.54 mouser.com 1 100nf Disc Capacitors 10pc pack of Caps $5.89 $5.89 bonanza.com 1 Blue red and yellow LEDs 120pc pack of assorted LEDs $3.36 $3.36 bonanza.com 1 SPST Switch ON/OFF Switch $2.50 $2.50 bonanza.com 1 PC Board 356 Hole board will use for OP Amp Circuit $2.49 $2.49 Radioshack 1 Printed Circuit Board 550 Hole board that matches the layout of modular breadboards $3.49 $3.49 Radioshack 1 Coaxial DC Power Plug Size M Coaxial DC Power Plug (2-Pack) $3.49 $3.49 Radioshack 1 A to B USB cable 3ft USB cable used to plug Arduino to PC $19.99 $19.99 Radioshack 1 Enclosures, Boxes, & Cases 7.5 x 4.5 x 2.2 Clear 7.5 x 4.5 x 2.2 $17.40 $17.40 Amazon.com TOTAL COST $120.79