Whenever I visit the RS site I’m put off by the eye-wateringly high prices. It’s still a decent site if you’re looking for reading matter such as datasheets and the like.
I have now almost all of the resistors on the control board replaced. Now I need to move around the knobs and the display, but that is hard! How do you get it do be good looking? Like, getting the distances correct? The knobs I would just put then as far away from each other as possible in the space, but how do you balance the display and the encoder?
When I made my VCA, I put the pots so close together that I can not fit any knobs on top of them now xD.
If you @popflier (or anyone else) could make me a simple drawing with measures (panel should be 10 by 20cm), I would be very grateful! Otherwise I’m just gonna go ahead and try anyways. 
While working on the BRAIN board, I found a line that covers one of the tracks, it is one which could not correctly be converted from eagle. For the other parts this was basically keepout area, but for this I am not sure. It looks like it is a ground track separate from the ground plane which goes to the bluepill and then to the MCP3204. I understand that they have made a separate ground to improve noise (probably), but why put a ‘line’ on top of it? is it to make sure that no other track crosses it? Any ideas?
Link to my KiCAD version:
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Yes, I am willing to work on this. The only thing I need to know, but could probably figure it out from the Soundforce page or even Sam’s panels, are the exact measurements. Then I can plug everything in accurately.
@sebastian…I am putting an order together today for Mouser. Did you change any of the parts from the original Soundforce BOM? If so can you tell me what they are so I can try and get it on my order?
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That is great! The front panel is 20 by 10 cm, I have not idea what that is in inches ;-). I need to check the measurements for the 7segment leds again. Everyone uses different knobs, but this should be no problem.
I am not changing parts, but I change the resistors for larger ones, because I think those are more widely available / easier to handle, but I am not sure on that. The sound force uses 204 (?) and I will use 207(?) as in Sam’s projects. And I change the jack sockets with molex connectors, you should find those and the sockets in the BOM for the performance filter.
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Here are the measurements for the display:
soooo… when someone here has these made on JLCPCB or whereever… please sell me a board lol.
and give me a BOM… lolol
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For whatever reason I cannot get the KiCad files to open. 
Maybe another version? I am using KiCad 5.1.4+dfsg1-1, release build on Ubuntu Linux. I will check the files again.
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Turns out that the blue pill boards from 2020 only have 64k flash :-/ also I am having trouble getting them programmed at all using a stlink v2 and Linux. Anyone done this already?
^ the thing preventing me from building the DIY Elements that was given to me…
64-pin SMD STM32 IC and programming said IC… lol
Did you ever get a response privately about programming your blue pill? I’ve spent the better part of a week looking at resources in order to program my Yarns DIY module with an Stlink v2. I’m using a linux virtual machine. There are a few tricks that you need to do for the blue pill. If you haven’t figured this out let me know and I will look for the video I found that seems to work. Also, it depends on which number of board you have (F1, F3, F4, etc…)
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Unfortunately not… I found out that for my particular version of the board I need a more recent version of the st-link Software, which is not yet in the Ubuntu repo. At this point I stopped.
I would be very happy if you can share how to do it!! For the braids I still need to wait till the blue pill with more flash arrives… :-/
Also I want to continue with the braids tht boards. I thought I had to adjust the space between the knobs and everything to make it fit the Kosmo format, but when I saw the braids frontpanel here in the forum, I thought, maybe the only change I need to do are the larger resistors and the larger jack sockets… I might even skip the resistors and just put them in at an angle.
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So, on this again, but now decided on not changing much on the soundforce design. Too much other stuff that I want to do! xD
I was checking the bom
and kicad file again and there is a non polarized EL of 10uF in there (C24). I forgot to put that on my last order, so I was wondering why that is needed and if I can get away with a polarized one.
In the schematics it is drawn as a polarized…
What are your thoughts here?
Does AUDIO_OUT go negative?
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It is the output of the MCP4822, so, should be between 0 and ~5V, I think.
It is the output of the MCP4822, so, should be between 0 and ~5V, I think.
The MCP4822 can produce either 2.048 V or 4.096 V (the latter via an internal 2× gain stage), but looks like it’s powered from the 3.3 V rail here so output is 0−2 V (the second stage is 5× so you get 10 Vpp out).
A polarized cap should work just fine here.
(I’ve found myself using NPs in the audio path lately even where they’re not strictly needed, but that’s probably just because I bought a batch from Tayda and I see them every time I go grab some electrolytics. Guess I like the colour or something 
)
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Some progress!!
Had to learn how to programm the stm32. First I had boards that really had only 64kb flash, but then I got two 128kb from ebay (UK). Then I needed to install stm32Cube. There was the problem of the correct java version. I read this: https://community.st.com/s/question/0D50X0000BsRNNV/stm32cubeprogrammer-execute-fail-with-could-not-find-or-load-main-class-comstappmain which points to here: https://stackoverflow.com/questions/61783369/install-openjdkopenjfx-8-on-ubuntu-20/62198111#62198111 and to here, the Liberia java stuff https://bell-sw.com/pages/downloads/ Where I had to download the FULL JDK for linux
Now I got a running stm32 Cube!!
With this running, I used the modfied firmware from soundforce.nl (I use the one with inverted encoder) to upload it to the stm32. But it would not run!! I found the option to start the code after uploading and it ran! but only until a reset/poweroff of the board! The issue was that the firmware starts at address 0x0804000 and the stm32 boots from 0x0800000! When I used the option to start after upload, it knew the address and started it from there, but the could only be done with a computer! So this is how I learned about bootloaders! You need to have a bootloader ad the first address 0x0800000! Luckily I found https://github.com/hadesbox/eurorack-with-binaries/tree/master/build where someone has published hexfiles of all the mutable instruments code! There was the braids bootloader! I could just upload both of them independently, because they have their location in the flash inscribed, just make sure you don’t erase anything while uploading the second.
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No output yet, but I can trace the signal from the DAC to the first stage of the opamp (oscilloscopes are great tools!!). Need to resolder the part after that and do some more testing…
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