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Working Through The Frustrations, Slowly

A project log for DrumKid: aleatoric drum machine

A lo-fi digital drum machine which uses randomness to create unpredictable beats. Runs on Arduino, with audio provided by the Mozzi library.

Matt BradshawMatt Bradshaw 05/07/2019 at 13:532 Comments

After yesterday's rant about not knowing what to do next, I decided to invest some time in making a new stripboard prototype. I was worried that the current design (batteries to voltage boost IC to Atmega328 to LM386) was just fundamentally too noisy, yet I couldn't think of a way to omit any of those elements without going all the way back to the drawing board. With this worrying thought in my head, I decided to convert my latest breadboard circuit into a stripboard circuit, in the hope that I would be able to build something with a clean enough audio output to give me some hope for the PCB version. It was a half-logical, half-desperate step, but (after several tense hours) it just about worked.

Before adding the decoupling capacitors, the noise was still horrible, but I tried adding a few different values to both sets of power/ground pins on the Atmega328 and gradually the noise became almost acceptable. Perhaps "acceptable" is a bit strong, but given that the stripboard circuit doesn't have a proper ground plane, I'm happy enough to now recreate this as a PCB, with slots for numerous decoupling capacitors.

Apologies that the last couple of posts have been a bit dull - I'm trying to be disciplined and sort out the fundamental issues like power supply, audio volume, and noise, before I keep working on the fun features.

Discussions

Mathias BrĂ¼ssel wrote 05/08/2019 at 19:19 point

Great to read you fixed most of the issues that worried you. Actually I found the former log quite interesting as well, because similar to you I am much more educated in programming than in electronics. Whenever you publish your final design I was thinking about building it on a breadboard with an Arduino Nono, but I guess the noise issues could still be similar to the ones you encontered with the Atmega328 (without the decoupling capacitors).

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Matt Bradshaw wrote 05/09/2019 at 20:14 point

Thanks, Mathias :) Hoping to post the breadboard instructions as soon as I'm happy with the code, maybe in a couple of weeks.

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