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Project Notes

#247 pedalShieldUno

Build and test a genuine pedalSHIELD UNO.

Build

Notes

In the AudioDSP project, I built an Arduino pedal/DSP unit based on the Electrosmash pedalSHIELD design. It worked well enough that I wanted to build the “real thing”, not only to give myself a good baseline on expected performance, but also to payback Electrosmash in a small way. Good OSH deserves support!

Unboxing and Parts Check

Reference Qty Value Check
C2, C5, C7, C8, C9 5 6.8nF
C3, C6, C10 3 4.7µF
C1, C11 2 100nF
C4 1 270pF
R12, R13, R10, R9, R6, R4, R3 7 4.7kΩ
R5, R7, R8 3 100kΩ
R1, R2 2 1MΩ
R11 1 1.2MΩ
RV1 1 500kΩ trimmer
D1 1 LED 3mm blue
U1 1 TL972 DIP8
socket 1 DIP8 socket
SW1 1 3DPT footswitch
SW2 1 Toggle switch
SW3, SW4 2 Pushbutton
Conn1,2,3,4 1 40 pin header
J1, J2 2 1/4” Audio Jack
  1 PCB
  1 Acrylic faceplate

kit_box

kit_parts

Assembly

About 60 minutes of soldering, continuity test and inspection.

Then an electrical test, powered independantly from 5V (i.e. no in the shield). All the test points check out OK, and current draw is ~2mA. Good to go .. and it works!

pedalShieldUno_test

Programming

The examples folder contains the collection of samples provided on the How to start programming pedalSHIELD UNO forum page. These are currently unmodified, and all work as expected.

Performance

It is surprisingly good, although it does tail off at the higher frequencies.

Quick test of the standard examples ..

pedalshield_uno_bit_crusher

This effect boosts the signal into overdrive (level determined by the pushbuttons).

scope

pedalshield_uno_booster

A simple volume boost (level determined by the pushbuttons).

scope

pedalshield_uno_clean

As you would expect: signal in, signal out. With a bit of high frequency noise..

pedalshield_uno_daft_punk_octaver

Effectively downsamples the input (level determined by the pushbuttons).

Trick effect. Solo not so nice - takes too much character out of the sound.

scope

pedalshield_uno_delay

Mixes a delayed signal with the input (delay depth determined by the pushbuttons).

Not so much delay, more like a bit of reverb?

scope

pedalshield_uno_distortion

Performs an asymmetrical clipping (top-side) to a level determined by the pushbuttons. Bluesy warm distortion..

scope

pedalshield_uno_fuzz

Performs a symmetrical clipping and boost to a level determined by the pushbuttons - signals above the threshold are thrown to the upper/lower rail.

Nice fuzz, full-on distortion. It does have a harsh cut-off at lower volumes, so palm muting doesn’t work so well. Good for djenting!

scope

pedalshield_uno_metronome

Generates a metronome tone, at a frequency determined by the pushbuttons.

pedalshield_uno_monitor

Performs a clean transform of the guitar signal, and logs the settings to the serial port.

Since the serial logging is performed within the interrupt routine, the signal transform is severely disrupted.

pedalshield_uno_signal_generator

Generates a tone described in a provided dataset.

pedalshield_uno_tremolo

Modulates the signal volume at a speed governed by the pushbutton setting.

Great effect. The scope trace doesn’t tell the story though .. it swells the volume.

scope

Construction

Schematic

Build

Credits and References

About LEAP#247 DSPGuitarArduino
Project Source on GitHub Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.