Designing a Eurorack Sequencer - Pt. 1: Digital to Analog
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- Опубліковано 29 тра 2018
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In this new series I'll be designing, prototyping and building a sequencer module for my eurorack sythesizer using the Arduino platform. In this episode, we connect the arduino to our 12v power supply and add a digital-to-analog converter output so our sequencer can output proper 0-8v CV signals.
Really informative series
Thank you for providing this excellent tutorial from start to finish!
great stuff well done
Hey I’m 3 minutes in and pretty excited about this series. Great video
reall interesting stuff! subbed
I think you just leveled up!
4:46 Shoulda measured the voltage across the LED *and* series resistor...
The LED has a fixed voltage drop across it when it's on.
man! awesome project!
This is great. I'm hooked. I'd pay money for training videos like this that also include a PDF explaining the wiring diagram at the end of each episode. Great job!
Thanks a ton! I'm still learning KiCad, but I'm planning to make the schematics and code available on github as soon as I figure out how to do it properly. This is supposed to be open hardware, after all...
@@extralifedisco Hi, please let us know if there are any schematics, I'm thinking about a similar project and this would really help! thanks a lot
@@bloodyMind4 sure thing, the complete KiCad files are available on Github. Haven't exported them to PDF but can do that next week when I'm back in SF
@@bloodyMind4 lol forgot the URL!github.com/matthewcieplak/super-sixteen
@@extralifedisco I'm very happy with what you have, I took a look at the kicad files and schematics, but have problems reading some symbols with project under /kicad, anyway would be interested to have a build, so if BOM + PCB, BOM + will do on breadboard, which size would be ideal, let me know what you think is the best approach at this point, I would like to learn how it works, also have a practical example of learning different functions of the circuit, possible hacking is in mind. I'm using TME.eu, but would do with any BOM if available, when u r back. Thanks a lot!!
Love this 😀 subbed
righteous indeed!
I want to see how the last thing you said would sound.
awesome
Thanks for that video man, very instructive. What made you choose SPI over I2C if I can ask? Thanks!
Familiarity mostly! MCP23S17 is available as an I2C chip but not sure offhand if the DAC is as well. When I started the project I didn't really understand the difference so world would probably make different choices doing it again!
Ah, very hip! I'm only peripherally familiar with the 'duinos, and i wasn't sure how folks were getting from the narrow TTL voltages it supports to the larger voltage swings we like in synth-land. Using that DAC chip makes a lot of sense. Does this particular chip allow you to *read* back the voltage, or would you need a different IC?
I don't think there's any voltage sensing on the 4922, and in any event it gets amplified and buffered out through the op amp (tl072) so the scaling changes as well. Later in the series (episode 6 maybe?) I demonstrate an adjustable calibration procedure that accounts for this nonlinear output variability in software, but it does require external measurement.
Just spotted this looking for some teensy audio stuff, now I have fallen down a hole to drive an FSS Brunswick DIY kit. Micro-microfreak anyone?
Righteous!
so you're using 1-pin to send 12-bits in succession that are somehow converted to analog value by the dac chip? is my superficial understanding correct? would you naturally want to use the highest timer frequency available to you to write the bits? are there any problems you face, or potential signal loss with this? is this better than other dac methods that use more pins, that could potentially communicate more bits simultaneously, more frequently, like a resistor ladder? you seem to have enough pins. sorry for all the questions, awesome video! thanks!
Yep, pretty much! Both SPI and I2C are serial protocols, so they're bits-in-series rather than parallel. For this project I end up using all the other pins for connecting other hardware (buttons, LEDs, jacks, etc) so 4-wire serial is better but I understand there are parallel DACs that would be better suited for some applications.
In this instance, a pitch control voltage output doesn't have to be that fast, it's probably running at a few hundred hertz is all, but that's plenty of resolution for pitch slides and smooth note transitions. Audio DACs need to run much faster, at least 20kHz or preferably higher as well as using higher bit depth for fidelity at low levels. That isn't realistic on a 16mHz clocked CPU, so you'd have to use a faster processor or an external audio codec.
4:05 that sample is from an EXCELLENT library called soulsoup if I'm not mistaken?
Well spotted! It is a STUPENDOUS library which I have criminally underused!
sooo good
Hi, great series. I am really interested in learning electronics in order to build modules just like you are doing. Did you teach yourself electronics pr are you an electrical engineer by trade? I am a programmer but have very little electronics knowledge, where do you recommend one starts? I’d love to be able to do exactly what you are doing, that is, think about a module, design it on paper and bring it to life. Loving this series. I’d also pay money for it.
Thanks so much for your kind words! I am also a programmer by trade - though electronics has been a hobby for some time. I still find it unintuitive and obscure but I have learned a lot from watching the fundamentals series on EEVBlog on youtube, building some guitar pedals (from kits and from schematics), and playing with arduino and axoloti. For a good learning text I recommend "Practical electronics for inventors" by Paul Scherz and Simon Monk, which explains the most common components, circuits, and tools in an accessible way. For practical experience I'd suggest buying some module kits to solder together to learn the techniques of assembly and basics of debugging with a multimeter. Also pick up a breadboard and an arduino and some parts kits from ebay (resistors, capacitors, leds, transistors, diodes) and you will be able to build lots of circuits from instructions online or reading open-source schematics (Mutable Instruments modules, for instance), which I find is the way I learn most new things. Good luck!
Exactly in the same spot, thank you both! @Extralife, would be nice to go more in depth. Such an interesting project
is it not possible to just use the arduino's ADC? It is 10 bits. What gives a 4.88 mV precision, is that not enough?
If I'm not mistaken, the Atmega328 has an ADC but not a DAC, so that's an input rather than output. It's used mostly for reading in analog potentiometer values. You can use a PWM output with a discrete lowpass filter and voltage follower as a rudimentary DAC but the slew rate is quite poor as you might imagine with all that capacitance in line.
Hi, did someone know the software used at 2:11 for desining the panel or maybe an other soft' for the same purpose ?
Use KiCAD. Yes there is some learning curve. But every pcb designing tool has it.
Hello Extralife,
I’m a Eurorack hobbyist who has an electrical understanding regarding assembly and part specifications. I’m looking to expand upon my knowledge in hopes I can build and understand simple circuits of my own. I’ve been having difficulty grasping concepts. So I’m curious if there are educational resources you can recommend? How did you learn?
-John
Hi John,
Simple circuits can be tricky, especially analog ones! I mostly learned by taking stuff apart and reading other people's schematics. Mutable instruments and Erica synths have a bunch of open source projects that you can access. Besides that I recommend watching some of the fundamentals Friday series on EEVblog, especially on op amps and decoupling.
I also got a lot out of "Practical electronics for inventors" which is a textbook that explains a lot of common circuit applications with a balance of theory and layman's explanation. By far the best teacher is building stuff yourself on the breadboard and seeing what can be changed and how it behaves. Good luck!