1. Analog/Digital Hybrid synthesizer
Group 28:
David Clapp – Computer Engineer
Matt Herr – Electrical Engineer
Kevin Morcombe – Electrical Engineer
Kyle Thatcher – Electrical Engineer

2. Motivation Lack of Analog Synthesizers in the market today
Produce more natural sounds while still enveloping the control that comes with a digital synthesizer
Analog synthesizers are elaborate and expensive.

3. Project Goals
Create an electronic musical instrument which produces sounds through analog means.
Tone generation through on board Oscillators
Various effects typically found in modern synths
Microcontroller Functionality
Complete Standalone device control
Control External devices through MIDI technology
Have other devices control this device through Bluetooth

4. Engineering Specifications
Component
Parameter
Specification
MCU
User Delay (Lag)
< 250ms
User Accessibility
MIDI 1.01 compliant
Musical Range
> 18 keys, octave switch
VCO
Pitch Accuracy
6 octave/ 20Hz – 21kHz
VCO/LFO
Signal Capability
Sine/Triangle/Square
VCF
Filter Range
20Hz – 21kHz
VCA
Distortion
< .01%

5. Project Flowchart

6. Control Systems

7. Control Systems

8. Control Systems – Design Selection
Goals:
All systems have no greater than 250ms delay
Multi-Threaded
Code scalable and modular

9. Control Systems -Microcontroller
Arduino Mega 2560
Raspberry Pi 3 Model B
Microchip PIC24FJ64GB406
Architecture
8 Bit
64 bit
16 Bit
Serial
UART, I2C, SPI
Memory
256KB
1GB
64KB
Price
45.95 35
4.62
Difficulty (1-10) 5 3 9

10. Control Systems - Technologies
Serial Communication Interfaces:
SPI serial bus
Serial Peripheral Interface
Synchronous Serial Communication
Used to read Rotary Encoder states
I²C serial bus
Inter-Integrated Communication
Used to:
Expand the number of available I/O pins
Control digital potentiometers
Programming Environment:
Operating System:
Raspbian
Language: C
Libraries:
PThread
WiringPi

11. Control Systems – Human Interface Devices
Tactile Switches
Indirect control of VCOs
Rotary Encoders
Indirect control of DigiPots

12. Hardware

13. Voltage Controlled Oscillator (VCO)

14. VCO and Signal Mixer VCO Goals and Objectives
1. Produce several waveforms – sine, square, triangle
2. Operate on +/- 12VDC input
3. Produce waveforms on audible frequencies 55 Hz – 2kHz
Signal Mixer Goals and Objectives
1. Allow operation of two separate VCOs
2. Tone stacking
3. Variable frequency mix

15. LFO – Low Frequency Oscillator

16. LFO - Design Selection Goals:
Provide modulation waveforms for VCO output (produce vibrato)
Provide variable frequencies from 2 to 25 Hz
Integrate seamlessly with project
Design
Range
(2-25Hz)
Triangle/
Ramp
Sine
Square
Hi-Lo Switch
Size
(PCB)
TL084
.5 – 40 Hz
CEM3340
2 – 30 Hz
XR2206

17. Voltage Controlled Filter

18. Voltage Controlled Filter
Goals
Create a viable effect utilizing a Low Pass Filter with adjustable Quality factor and Cutoff range.
Capable of being controlled by the LFO
Cutoff Sweep
Controllable Via the user.

19. Attack Release Envelope

20. Attack Release Envelope
Goals:
Allow the user to alter their attack and release times to fit their desired needs.
Design Criteria:
Focus on Simplicity and functionality
Time of envelope based on qualitative response.

21. VCA – Voltage Controlled Amplifier

22. VCA - Design Selection Goals:
Control/Amplify the final audio signal from the VCF/Envelope
Minimize noise/distortion in signal
Integrate seamlessly into project
Design
Linear
Response
Exponential
Low Noise
Low Distortion
Size
LM13700
<.01%
V2181
THAT2181

23. Power Supply

24. Power Supply Goals and Objectives
1. Eliminate need for batteries – cost waste
2. Input power from wall; 120V RMS, 60 Hz
3. Produce consistent +12 and /- 15VDC output

25. Administrative Content

26. Work Distribution Key: Primary – Green Secondary – Blue Member Human
Interface
Power
MCU
VCO
VCF
VCA AR
LFO
David
Kevin
Kyle
Matt
Key:
Primary – Green
Secondary – Blue

27. Budget Budget Description Vendor Price Quantity Total Cost
Microcontroller
 Mouser $ 1 $
Custom PCB
 Elecrow $
1-5
$50 - $250
VCO
Mouser $ $
LFO $ $
VCF $ $
VCA $ $
AR envelope generator $ $
Housing Unit
Undertermined  $ $
Shipping $ $
Misc Unforseen Costs $
Total $

28. Progress

29. Challenges/Successes
VCO
MIDI
VCF
Bluetooth
VCA
Code Stability AR
LFO
PCB Design
Case Design
Octave Switches
Frequency Tuning