Build and test a genuine pedalSHIELD UNO.
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!
| 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 | √ |
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!
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.
It is surprisingly good, although it does tail off at the higher frequencies.
Quick test of the standard examples ..
This effect boosts the signal into overdrive (level determined by the pushbuttons).
A simple volume boost (level determined by the pushbuttons).
As you would expect: signal in, signal out. With a bit of high frequency noise..
Effectively downsamples the input (level determined by the pushbuttons).
Trick effect. Solo not so nice - takes too much character out of the sound.
Mixes a delayed signal with the input (delay depth determined by the pushbuttons).
Not so much delay, more like a bit of reverb?
Performs an asymmetrical clipping (top-side) to a level determined by the pushbuttons. Bluesy warm distortion..
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!
Generates a metronome tone, at a frequency determined by the pushbuttons.
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.
Generates a tone described in a provided dataset.
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.
- pedalSHIELD UNO - getting started guide
- pedalSHIELD UNO - main page
- pedalSHIELD UNO Schematic
- How to start programming pedalSHIELD UNO
- The Arduino Guitar Pedal - another pedal proejct
- ..as mentioned on my blog