05/01/03 Brian Crosby Final Presentation Auto Tuner

05/01/03 Brian Crosby Final Presentation Background Manual tuning a string instrument to reference tones takes skill, and is often a time consuming and error-prone process.

05/01/03 Brian Crosby Final Presentation Problem Develop a hand held system that automatically tunes a string instrument quickly and effectively.

05/01/03 Brian Crosby Final Presentation Solution ¼ jack to listen Filter to clean signal Comparator to convert signal Micro-controller to measure and decide Gear motor to correct and adjust

05/01/03 Brian Crosby Final Presentation What a Signal is

05/01/03 Brian Crosby Final Presentation System Overview Microphone Comparator Gear Motor Instrument is plucked High Low Micro Controller Filter

05/01/03 Brian Crosby Final Presentation What It Looks Like ON / Off Six position Switch Mode Selection LCD Display Tuning peg Heads

05/01/03 Brian Crosby Final Presentation Presentation Breakdown Electrical – filter, converter, micro controller, motor driver Software – Frequency comparisons, overall functions Mechanical – Torque, motor, gears

05/01/03 Brian Crosby Final Presentation Auto Tuners Electrical Concepts

05/01/03 Brian Crosby Final Presentation Electrical Overview FILTER Circuit PIC COMPARATOR H BRIDGE MOTOR DRIVER GEAR MOTOR INPUT ¼” JACK On/OFF BUTTON MODE BUTTON BATTERY DISPLAY SIX POSITION SWITCH Two Circuit Boards DISPLAY

05/01/03 Brian Crosby Final Presentation Input Filter Guitar freq. Ranges. – 330hz to 1.3khz. Low passed freq. – R=1k, C=.05uf. – Filters out frequencies above 2 kHz.

05/01/03 Brian Crosby Final Presentation Comparator Circuit for Strings Parallel combination of resistors lowers comparator reference to 75mv for the B and High E strings Voltage divider set comparator reference voltage to 100mv for the E,A,D,G strings

05/01/03 Brian Crosby Final Presentation Guitar and Comparator Signals Set Trigger Point for comparator

05/01/03 Brian Crosby Final Presentation Micro-Controller 16f877 Pic Voltage range – 3.0V to 5.5v Power consumption 5.0v

05/01/03 Brian Crosby Final Presentation Motor Driver Motor Driver

05/01/03 Brian Crosby Final Presentation Power 6 AA batteries – 9Volts Current draws – full load – 60 no load – down

05/01/03 Brian Crosby Final Presentation Auto Tuners Software Concepts Auto Tuner

05/01/03 Brian Crosby Final Presentation Start UP Power UP Auto tuner Welcome StandardDrop DEb Select string Pluck String Choose Tuning

05/01/03 Brian Crosby Final Presentation Signal Process Master Clock System Shut Down Memory Check Capture Clock Motor OUT LowHigh Signal from guitar Tuning keys are turned

05/01/03 Brian Crosby Final Presentation Master Clock Used – LCD Backlight, Off Button, Power down Overflow interrupt – 13ms – Counts, coin in the bucket – Resets buttons, switch, captures Example: – Power down in 2 minutes – 2min = 120 sec = 9231 coin in bucket

05/01/03 Brian Crosby Final Presentation Capture Clock Overflow – 26ms, 38.46hz. Signal resets timer – Rising edges Capture used – 400ns blocks

05/01/03 Brian Crosby Final Presentation 400ns Blocks

05/01/03 Brian Crosby Final Presentation Software sample callLCD_Init;Display the splash screen for 3 seconds. callDelay10ms movlwMSG1 callLCD_PrintString callLCD_NewLine movlwMSG2 callLCD_PrintString callDelay1sec Main: callLCD_ClearScreen ;Put the current capture value on the screen. callDelay10ms movlwMSG3 callLCD_PrintString callLCD_NewLine

05/01/03 Brian Crosby Final Presentation Software Main Loop Main_Loop: callDelay100ms bcfPIR1, CCP1IF; Clear the Capture module interrupt flag bcfPIR1, TMR1IF bsfT1CON, TMR1ON; Turn on the timer1 ; Wait for the next Capture event. Main_Loop_Wait: btfssPIR1, CCP1IF gotoMain_Loop_Wait clrfTMR1L clrfTMR1H btfscPIR1, TMR1IF ; check if timer 1 overflows and skips next command if not GOTO Main_Loop

05/01/03 Brian Crosby Final Presentation Auto Tuners Mechanical Concepts

05/01/03 Brian Crosby Final Presentation Mechanical Overview Battery Pack Pic Circuit Board Input / output circuit board Gear Motor LCDLCD Gear Gripper for E,A,D strings Gripper for G,B,E strings

05/01/03 Brian Crosby Final Presentation Torque and Gear Motor Guitars Tuning Keys – Highest, tightening = 10.8 oz / in – Lowest loosening = 1.8 oz / in Matching gear motor – 41.7 oz / 12 volts – 9 volts Estimated torque = 31.3 oz / in

05/01/03 Brian Crosby Final Presentation Gears Considerations – 30 RPM No change – Torque 31 oz / in No change Spur Gear – Two of the same size – 1:1 ratio

05/01/03 Brian Crosby Final Presentation Prototype Cost Estimated manufacturing cost $90.00 Suggested retail $160.00

05/01/03 Brian Crosby Final Presentation Schedule

05/01/03 Brian Crosby Final Presentation For More Information Visit the Auto Tuner web page: /auto tuner/webpage

05/01/03 Brian Crosby Final Presentation Thank You Sam Colwell Mike Weidman Roger Howes Andre St. Denis Paul Johnson

05/01/03 Brian Crosby Final Presentation Any Questions ???