Arduino Guitar PedalIan AndalIME 458Dr. Pan

Agenda•Introduction•How it works:

▫PCB Schematic▫Input Pre-amp Stage▫Arduino Digital Signal Processing▫Mixer/Output Stage

•Manufacturing Process•Finished Project•Results

Introduction•Goal of this project is to replicate an

Instructables project, the Arduino Guitar Pedal

•The Arduino Guitar Pedal is a low-fidelity (lo-fi), multi-effects digital guitar pedal with an Arduino Uno acting as the digital signal processor

Schematic

PCB Layout

BOM

Input Pre-amp Stage• The guitar signal goes into the

circuit via J1 connector and goes to the TL082 IC (U2) at pin 5 for amplification

• R18 ,R14, and C5 makes the op-amp act as an active low-pass filter.

• R2 and R9 create a voltage divider to set the reference voltage of 4.5V for the non-inverting inputs of the op-amps.

Arduino Digital Signal Processing• R23 scales the amplified

guitar signal and that signal is AC couple to a resistor divider through C9.

• The resistor divider shifts the DC level of the guitar signal to around 0.5V

• The analog-to-digital converter samples the signal via A0 pin for signal processing

Mixer/Output Stage• The Arduino creates pulse-width

modulated signals that go through C7 for mixing

• The pulse-width modulated signals and the clean guitar signal mix in via the second op-amp in the TL082 IC (U2)

• This amplified mixed signal goes out to the guitar amp via AC coupling through C3 and the J3 connector.

Design Process•All through-hole components

•Circuit mainly consists of resistors, capacitors, and through-hole pads for wires to connect to

•Easier assembly process

Finished Project

Results• Guitar pedal functioned as expected; played

various programmed guitar effects

• Low quality or lagging in performance for certain effects due to:▫Memory limitations of the Arduino▫Bit resolution of the ADC

• Could not fit all the contents into the case due to my miscalculations on the physical dimensions of the PCB and the components

Reference•More information on the Instructable for

the Arduino Guitar Pedal can be found here:

http://www.instructables.com/id/Arduino-Guitar-Pedal/