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TOPIC: Troubleshooting Pedal

Troubleshooting Pedal 7 months 5 hours ago #1406

Hello!

I decided to get into this as a bit of a summer project as I prepare for college. I have dabbled in arduino and electronics before this but this is my first real project. I'm a bass player and I looked into this project as a way that I could make some pedals and learn some new skills.

After putting together my PCB I plugged it in with the default fuzz program and got, well, fuzz... but not the right kind! The pedal gives off some static feedback, and doesn't seem to correctly/accurately convert the waves. Solder connections look good to me... Electrolytic Capacitors seem to be in the right direction... All TPs have the correct voltages as far as I can see...

I loaded up the Sine wave generator and I can say for a fact that the output side is definitely problematic, at least. the "sine wave" sounded like someone starting up a motor bike, haha!

I also loaded up the clean pedal. Although not as destructive as the sounds of the sine wave or fuzz pedal, it still made some noise that renders the pedal unusable in a band setting. If this isolates the input side (unclear by troubleshooting page) it seems like there is still a problem that exists here as well.

I attached 2 pictures (front and back) of my board.

Thanks for any pointers you can give me to help me figure this out. It may be something I'm just over-looking or I may just not have the smarts to fix it on my own, haha!

if you need the video I can edit in a link to youtube, otherwise I won't bother with uploading it. The video is of the sound while using the clean pedal. The Sound heard on the clean pedal exists when any program is running (or none at all). This fact makes me think it's a bad connection or the chip but I'm not certain... This sound is different than the sound of the choppy sine wave though. bypass mode has no issues (as expected).


-mistroagentzulu
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Last Edit: 6 months 4 weeks ago by mistroagentzulu.
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Troubleshooting Pedal 6 months 3 weeks ago #1409

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Hi, welcome to the group! ;)
The soldering job looks spot-on, not issues there. Also, the components placement looks fine (I cannot see the op-amp marking to check if its upside down, but the rest looks neat)

First things first, as you said, the voltages are correct, but can you double check that:
- you have GND on pin 4 and +5V on pin 8 of the op-amp?,
- could you also check the voltage after and before R2?
www.electrosmash.com/images/tech/pedalsh...ld-uno-schematic.png

The sinewave generator should sound fine, at the beginning sounds like a motorboat but as you press the push-buttons, the frequency increases and the sine-wave sounds better.
- Are you sure that you are taking the output from the left-hand side connector of the board?

Also, do you have any nasty noise when the 3PDT switch is bypassing the effect? (effect off).

Make us know about your progress.
Last Edit: 6 months 3 weeks ago by Ray.
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Troubleshooting Pedal 6 months 3 weeks ago #1410

Hi Ray,
Yes, all correct voltages still...
The voltage before and after R2 is 2.4 to 1.4, seems like a voltage dropout of 0.1 volts through the circuit which shouldn't be a big deal I would assume.

I see what you mean about the sine generator, if the lowest octave on it is supposed to sound like that, then yes, it's working as intended in that regard.

Bypass doesn't have any issues.

I've decided to post the video because it still doesn't explain this noise that I get with every program for the pedal. You might need to volume pretty high to hear it in the video, but trust me, in person it's pretty loud. This specific example is with the clean pedal code, when you don't hear noise the bypass is switched (effect off), and obviously when you hear that noise the effect is supposed to be on.



Thoughts?
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Troubleshooting Pedal 6 months 3 weeks ago #1411

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I see what you mean about the sine generator, if the lowest octave on it is supposed to sound like that, then yes, it's working as intended in that regard.
So, the sinewave generator creates a tone that you can modify with the push-buttons.

Having a look at your video (you are not playing but I assume that if you play the guitar signal will go through), the background static hiss could be reduced trying 2 things:
The Arduino board was never intended to be an audio processor, so you will always have a small amount of background hiss, but it should be quiet in comparison with your guitar signal.
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Troubleshooting Pedal 6 months 3 weeks ago #1412

I didn't expect there to be this much background noise coming through the system, but yes the guitar does come through louder. It makes something like this difficult to use in a live setting with the current settings though, especially when doing quieter sets.

Is the noise I'm experiencing on a code level, or an electrical level? (The way I understand it, it originates from the arduino).

It sounds like I'm going to be out on my own for this one but if you already know that the noise isn't something that's possible to silence with the UNO, are there other devices that I can look towards for audio processing that are more precise, but still feasible for smaller projects like this?

Thanks for the help Ray!
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Troubleshooting Pedal 6 months 2 weeks ago #1417

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Is the noise I'm experiencing on a code level, or an electrical level? (The way I understand it, it originates from the arduino).
The noise comes from the electrical level; the Arduino SMPS power supply is noisy by default and the ADCs are affected by this. I have tried modifying the Arduino board itself but without much success.
If you play the sinewave generator, you would see that there is almost no noise at all in the signal, so that probably means that all the noise is coming from the input stage/ADCs. You can reduce a bit more the noise if you increase the size of the 6.8nF to 10nF (or even more16nF, 22nF) that will cut more the high freqs.

It sounds like I'm going to be out on my own for this one but if you already know that the noise isn't something that's possible to silence with the UNO, are there other devices that I can look towards for audio processing that are more precise, but still feasible for smaller projects like this?
The arduino board was never conceived to be an audio processor, so some background low hiss is going to be there. You can improve it by using a good power 12V external power supply. Most of the times you won't notice this noise (specially if you play distortion, fuzz, bit crushers, etc)

I am not aware of any other affordable DIY solutions out there :(
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Troubleshooting Pedal 6 months 2 weeks ago #1418

Alright,

I'll play around with it this summer and do some testing in an on-stage environment too. I'll update if I do find anything else that you haven't already mentioned.

Thanks a ton Ray!
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Troubleshooting Pedal 6 months 1 week ago #1422

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Hi, that's great, any feedback to improve the project is always welcome!
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