you could possible drill mounting holes in the ground plane??? there is quite a lot of space here and there
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yeah might do that.
one more question. the BOM mentions 4x jacks +1x power jack. is that correct? if so, what is the input-jack for? does it take audio-in?
thanks, where is that schematic from?
Patreon. 
Also in unrelated news, I figured out my filter/cutoff knob issue… it turns out there was just a bad connection between the 100k resistor and the middle leg of the pot. 
Speaking of which, I was able to figure this out due to the old schematic from Patreon, so clearly it pays to be a patron!
In regards to my other issue with pots being too short, pot extensions are super expensive it seems, although you could 3D print some I’m sure, I just went and bought 25mm long shafts, unfortunately the only thing I could find were center dented pots, but I can live with that for now. Time to finally put mine in a case!
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I got some comically large-sized knobs, too big? Got some smaller ones on the way but it’s kind of ridiculous in a fun way. What do you guys think?
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I like big knobs, but I also like big spaces between knobs.
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I like big knobs, but I’m also a big fan of mixed-size knobs. Keep some of the big’uns!
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Yeah I’d keep them for sure but some of the spacing is pretty tight! But, it’s also fun to just run the palm of your hand down a side and move them all, haha.
@ChristianBloch That might be a good call, got some smaller ones on the way, we’ll see!
I’m also thinking of a potential “mod” to add a knob in that spot where there is nothing, maybe a volume knob or an attenuator for the CV inputs?
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Finished! Lots of fun!
One slightly strange issue though - the module doesn’t always power up when the synth is switched on, i.e. sometimes the oscillator LEDs don’t come on / no response from gate or trigger. It then comes back again after switching off and on again, and then works perfectly.
It’s being powered from a +/-15V supply fed to the inputs on the voltage regulators. No D9-D14 diodes or C17-C18 big caps.
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Probably the regulators being unhappy with something.
15 V isn’t that far from where the 7812/7912 regulators stop regulating (typically 14.5-14.6 V) so if you drop enough voltage on the way in you may go below that, but you should still get a voltage from them if that happens.
I think stability issues are more likely; you probably want some supply-side caps, but more like a handful of uFs. Datasheets recommend a minimum of 0.22 uF near the regulator on the supply side for the 7812 and 25 uF (or 2.2 uF tantalum) for the 7912.
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Thanks @fredrik - you’re right that the 7812 isn’t happy. I’ve tried the caps but still getting erratic behaviour, will take another look this evening…
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Wow looks really nice. You got the whole pcb behind there???
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You could try adding 100 nF ceramics on the output side, near the regulators (maybe across the D13 and D14 diodes). There are bypass caps near the 3340s but the change from ripply 16.5 V or so to smooth 15 V might be enough to make the regulator forget what it’s there for.
EDIT: The diodes are pretty far away from the regulators; you may want to find a closer spot (possibly across the legs of C4/C5, or even the regulators – but if you do that, note that they have different pinout; output is rightmost pin 3 on both but GND is in different locations, so use 2 and 3 on the 7812 and 1 and 3 on the 7912.)
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Yes, just about! It’s tight, but I made a 45 degree bracket, and it just fits in the 5U cabinet with a few mm to spare.
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That is quite possibly the most beautiful item in the world with the word “Fart” prominently displayed on it. Nice Work!
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Instead of a push button, there should be a little finger you have to pull.
Hey, @lookmumnocomputer, you should do this with your robot hand!
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So I tried the suggested capacitors, including a 100nF ceramic directly over pins 2 and 3 on the 7812, but the issue persisted.
It appears that the problem has disappeared after swapping the L7812CV for a L7812CV3. I don’t know if that 3 on the end is significant, or if there’s just a difference between those individual regulators (although I did try a few other L7812CV regulators).
So the module is functioning perfectly now, although I must admit that I don’t fully understand what solved the issue.
Thanks very much for your help with this!
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I sure wish this was cheaper:
https://www.amazon.com/dp/B000FOW3Q0/ref=cm_sw_em_r_mt_dp_U_G-p8EbEFTRQJZ
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Odd. L7812 is STMicroelectronics’ version, and they recommend slightly different capacitor values (I should have asked which one you used) but I cannot find any trace of a CV3 in their current documentation, or on distributor sites.
There are people selling “genuine L7812CV” on eBay where the photo clearly says L7812CV3, though, and I found a version of the datasheet from 2004 that mentions an L7812CV1 package variant, so I guess it’s some variant that’s no longer manufactured. Why a slightly different package would fix your issue is more than I can figure out 
(and yeah, there are a few Chinese manufacturers that make L7812s too, but I don’t think there’s enough money in this one to motivate outright fakery.)