Project

# Title Team Members TA Documents Sponsor
18 Affordable Analog Synthesizer
 Breanne Warner
Michael Jamrozy
Yash Bhushappagala
 Feiyu Zhang design_document1.pdf
design_document2.pdf
design_document3.pdf
final_paper1.pdf
photo1.jpg
photo2.jpg
presentation1.pdf
proposal1.pdf
video1.mp4
## Team Members
Michael Jamrozy (mjamro3), Breanne Warner (breanne2), Yashas Bhushappagala (yab2)

# Affordable Analog Synthesizer

# Problem
The high cost of analog synthesizers make them prohibitively expensive for anyone interested in synthesizers as a hobby. One can easily expect to spend $300 or more on a new, low-end analog synthesizer, and the cost increases significantly for more capable synths. Such a high upfront cost discourages many people from purchasing and learning about synthesizers.

# Solution Overview
We propose to build a box with a MIDI input and audio output. The controls for the synthesizer, which will mainly consist of knobs and switches, will be located by the front panel and be organized by their function. The controls include things such as the cutoff for the filter, the attack, decay, sustain, and release of the ADSR envelope generator, etc. The internals of the box will be built with cost in mind, using only readily available and cheap components to keep the cost as low as possible. There will be four main parts to the project: the power supply, the interface with the MIDI keyboard, and the analog synthesizer, and the audio output.

# Solution Components

## Power Supply
We plan on using an existing power supply.

## MIDI Subsystem
The standard MIDI interface allows the synthesizer to be connected to any MIDI keyboard. The microcontroller will read the pins of the MIDI cable and determine which keys are currently pressed, and then it will output this information to the synthesizer. This step will likely require a DAC to feed into the voltage-controlled oscillator described in the next section. Additionally the microcontroller will have the ability to play back MIDI files stored on an SD card.

## Synthesizer Subsystem
This synthesizer will use subtractive synthesis. First generate a wave with a pitch corresponding to the key pressed using a voltage-controlled oscillator, which will either be a square wave or triangle wave. The next stage is to filter them using a low-pass filter with a controllable cutoff. Then the sound will go into a voltage-controlled amplifier whose input comes from an ADSR envelope generator, which can also be used to modulate the cutoff frequency. The synthesizer will have a low-frequency oscillator which can be used to modulate either the pitch, amplitude, cutoff frequency or pulse width in the case of the square wave. All knobs on the front will be attached onto potentiometers on the circuit board that control voltage dividers, and these voltages will go to the various voltage-controlled amplifiers, filters and oscillators.

## Audio Output Subsystem
Built in speaker as well as auxiliary output for external speaker.

# Criterion for Success
- Recreate well known synth sounds used in popular songs. Some examples of sounds would be the synthesizer parts of Cinema Show, On the Run, and Lunar Sea.
- Controllable with at least 24+ keys from the MIDI keyboard.
- Read key inputs from a file on an SD card and play them through the synth as if the notes were being played on the keyboard. There can be multiple songs loaded onto the SD card and the user can cycle through them to play a specific song.

Electronic Replacement for COVID-19 Building Monitors @ UIUC

Patrick McBrayer, Zewen Rao, Yijie Zhang

Featured Project

Team Members: Patrick McBrayer, Yijie Zhang, Zewen Rao

Problem Statement:

Students who volunteer to monitor buildings at UIUC are at increased risk of contracting COVID-19 itself, and passing it on to others before they are aware of the infection. Due to this, I propose a project that would create a technological solution to this issue using physical 2-factor authentication through the “airlock” style doorways we have at ECEB and across campus.

Solution Overview:

As we do not have access to the backend of the Safer Illinois application, or the ability to use campus buildings as a workspace for our project, we will be designing a proof of concept 2FA system for UIUC building access. Our solution would be composed of two main subsystems, one that allows initial entry into the “airlock” portion of the building using a scannable QR code, and the other that detects the number of people that entered the space, to determine whether or not the user will be granted access to the interior of the building.

Solution Components:

Subsystem #1: Initial Detection of Building Access

- QR/barcode scanner capable of reading the code presented by the user, that tells the system whether that person has been granted or denied building access. (An example of this type of sensor: (https://www.amazon.com/Barcode-Reading-Scanner-Electronic-Connector/dp/B082B8SVB2/ref=sr_1_11?dchild=1&keywords=gm65+scanner&qid=1595651995&sr=8-11)

- QR code generator using C++/Python to support the QR code scanner.

- Microcontroller to receive the information from the QR code reader and decode the information, then decide whether to unlock the door, or keep it shut. (The microcontroller would also need an internal timer, as we plan on encoding a lifespan into the QR code, therefore making them unusable after 4 days).

- LED Light to indicate to the user whether or not access was granted.

- Electronic locking mechanism to open both sets of doors.

Subsystem #2: Airlock Authentication of a Single User

- 2 aligned sensors ( one tx and other is rx) on the bottom of the door that counts the number of people crossing a certain line. (possibly considering two sets of these, so the person could not jump over, or move under the sensors. Most likely having the second set around the middle of the door frame.

- Microcontroller to decode the information provided by the door sensors, and then determine the number of people who have entered the space. Based on this information we can either grant or deny access to the interior building.

- LED Light to indicate to the user if they have been granted access.

- Possibly a speaker at this stage as well, to tell the user the reason they have not been granted access, and letting them know the

incident has been reported if they attempted to let someone into the building.

Criterion of Success:

- Our system generates valid QR codes that can be read by our scanner, and the data encoded such as lifespan of the code and building access is transmitted to the microcontroller.

- Our 2FA detection of multiple entries into the space works across a wide range of users. This includes users bound to wheelchairs, and a wide range of heights and body sizes.