Tube Tremolo Pedal

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Rack Mount Tube Tremolo Spring 2005 Senior
Design II ECE 4522-04
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Design Team
Hardware Software Power Scheduling Website
Jonathan Cartrette (team leader) X X X X
Matthew Weinrich (team member) X X X
Will Allgood (team member) X X
Casey Petty (team member) X X X
Dr. Marion Hagler (team advisor)
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Abstract

• Our group has designed a vacuum tube-based
  tremolo unit that can be used with any standard
  electric guitar or bass guitar. The unit
  utilizes a digital control structure that allows
  hands-free alteration of the effects tempo.

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Motivations

• Many highly desirable features are possible with
  digital technology.
• Analog equipment continues to be competitive with
  digital technology.
• We know of no tube-based effects units with
  digitally-controlled features.
• A market has existed for many years and is
  extensive enough to support our product.
• Limited availability will directly influence
  demand.

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What Is Tremolo?

• An input signal is output with periodic amplitude
  reductions.

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Senior Design I Summary

• Combined digital and analog (vacuum tube)
  technology
• Constructed a power supply, digital control
  structure, LED display, and effects circuit on
  breadboards
• Constructed a prototype footswitch

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Senior Design II Goals

• Simplify hardware design
• Implement PCB design cycle
• Improve software
• Additional features
• Packaging
• Testing

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Old Hardware Schematic(Monophonic)
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Old Hardware Simulation(Monophonic)
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New Hardware Schematic(Monophonic)
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New Hardware Simulation(Monophonic)
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PCB Design

• Improve layout for easier implementation
• Design PCB traces
• Send off design for printing
• Populate PCBs

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Software

• LED output by timer interrupt
• Triplet (1.5x) toggle instead of triple (3x)
  multiplier
• Accommodate for additional input
• Error-checking output tempo code
• Switch debouncing

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Additional Features

• Stereo operation with panning

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New Hardware Schematic(Stereophonic)
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New Hardware Simulation(Stereophonic)
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Additional Features (cont.)

• Driver waveform choice (square or sine)

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Additional Features (cont.)

• European outlet support
• Automatic discharging of high voltage capacitor

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Packaging

• Requirements
• Main unit must fit in a 19 EIA standard rack
• Footswitch must be large enough and sturdy enough
  to be used in a live music situation
• Solutions
• Main unit in 17.5 wide, 1.75 tall steel case
  with 19 front panel for mounting
• Footswitch in 10 wide, 5 deep, 2 tall steel
  case

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Testing

• Objective Testing
• SNR and THD tests with DSSF3
• Power supply and signal level tests with
  multimeter
• Subjective Testing
• Blind listening survey of musicians and
  non-musicians comparing our product to our
  competitors

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Cost Summary
Quantity Price/1000
Rotary Encoder 1 2.35
7-Segment LED 1 4.47
PIC18F442-I/P 1 5.26
230V Transformer 1 8.31
12 V Transformer 1 7.52
Opamps 2 0.41
25MHz Clock Oscillator 1 0.91
1000uF, 35V Capacitor 3 1.07
1000uF, 250W Capacitor 1 3.21
Full-Wave Bridge Rectifier 1 1.74
MAX517 8-bit D/A 1 2.73
Rectifier Diodes 3 1.21
Voltage Regulators 3 3.07
12AX7 Vacuum Tube 1 12.00
12AX7 Socket 1 2
Relays 5 2.51
Resistors, Capacitors, etc. Resistors, Capacitors, etc. 6.00
Rack Mount Case 1 34.14
Footswitch Case 1 20.00
Marine Switches 5 7.00
TOTAL 158.88

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Acknowledgements
Dr. Bob Reese
Dr. Marion Hagler
Dr. Jim Harden
Dr. Joe Picone
Dr. Ray Winton
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Any Questions?