All-in-One Guitar Amplifier Paul Shumay Bruce Ankenbrandt Sarah Echler Brynn Schultz Instructor Dr. Gursel Serpen Advisor Dr. Richard Molyet

Introduction Paul Shumay - Team Leader Bruce Ankenbrandt Sarah Echler Overdrive and Reverb Effect Design Bruce Ankenbrandt Fuzz Effect Design, Lead Integrator Sarah Echler Microcontroller Programming Brynn Schultz Power Supply Design

Background Information What is the role of guitar effects devices? most commercial amplifiers have effects built in some manufacturers build single effect devices usually has foot controls Common features: Applies a single effect to the guitar signal Multiple power sources are required for multiple effects Requires time for setup and disassembly

The All-in-One Guitar Effects Box Design contains multiple devices Amplifier was omitted from the design Requires a single power source Device is portable Utilizes an LCD display for the user interface Integrated footswitch for control while playing

Functional Overview

Power Supply 120v transformer Bridge rectifier 220uf Smoothing capacitors +/-9 output voltage The power supply is made up of 3 parts. The transformer which we chose to be 120v because it would get us close to what we need for the effect circuits which is +/-9v. The bridge rectifier is used to convert the ac voltage signal into the dc voltage signal. The DC supplied by the rectifier would consist of of sine waves with the voltage fluctuating. This would be make the power supply useless for the dc circuits. The circuits would not function due to the fact the power would be removed every half cycle. To smooth this output signal smoothing capacitors were added. Over specifying the size of the capacitor needed would add unnecessary cost and weight and under specifying would lead to poor performance quality. With calculations we discovered that 220uf would give us the results we needed. This supplies power to the effect circuitry. http://www.electroschematics.com/5678/

Power Supply

Microcontroller Four basic components Arduino Micro Potentiometer circuit Control Relays LCD screen

Arduino Micro Controls all non-signal circuitry Potentiometer/Voltage divider circuit Control relays LCD Screen Uses a footswitch to control the inputs/outputs Operate on 9V Contains 5V regulator

Potentiometer Circuit Potentiometers monitor the modification level of the signal Voltage divider is used to monitor this modification Selectable by the footswitch

Control Relays Signal flows through effect Uses 5V or 0V for Logic Activates one relay at a time to pass the signal through Clean (Unmodified) Fuzz OverDrive Reverb

LCD Screen System Status Displays Potentiometer Position Which effect is selected How much distortion applied Potentiometer Position Uses voltage divider to display a percentage

Fuzz Effect A Type of Distortion similar to clipping Uses an asymmetric clipping Uses a BJT saturation and cutoff modes Controlled by gain and capacitor filtering

Fuzz Waveform

Fuzz Effect

Overdrive Effect What is Overdrive? Different Types of Clipping Hard Clipping Soft Clipping

Overdrive Effect Puts circuit into overdrive to force the Op Amp to clip the guitar signal Operates based on underpowering a single LF356 Op Amp Potentiometer in feedback loop to give user control over the severity of clipping

Overdrive Effect Overdrive Effect

Overdrive Effect

Reverb Effect What is Reverb? Different simulated environments

Reverb Effect Circuit needs to add delayed copies of the signal before output Can be created either digitally or with a reverb tank Amplifiers connected at the input and output of the reverb tank

Reverb Effect

Reverb Effect

Summary Three unique effects in one device One power supply for the device Portable and compact Footswitch for easy control while playing LCD display for readability Saves user cost of buying multiple devices

Progress Report Completed: In progress: To be completed: All circuits prototyped Testing is near completion on individual circuits In progress: Arduino programming Enclosure construction To be completed: Acceptance testing

Questions?