My build progress

Is that Zynthian?? i couldnt get it to work for me. Looks like a nice build =D

Sounds like my first synth case; I did buy a pair of TipTop rails, but the rest was Coroplast (repurposed political campaign signs), black sticky vinyl, and black duct tape. Served me well for over a year until I filled it up and built something bigger.


Oh no, I assure you, it does NOT sound like your first case.



It is a LMN-3 (project home). i have two pcbs on sale in the BST thread. It is a cool but expansive project. Mine uses a pi4 8gb and boots up in ~30 seconds. i hope it gains traction and the software gets improved. there is a lot of potential in it. video review (yt)


Yeah, it wasn’t. I should really post this in the litany of dumbassery thread:roll_eyes:

I’m not really sure how anything made a noise and didn’t pop on previous steps, as I had the breadboard round the wrong way, in an effort to align it with the diagrams. All would have been fine if I’d also turned the power header round too, so I was sending -ve into +ve… :person_facepalming:

I have forgotten pretty much everything I learned last winter.

Edit: It also looks like I’ve blown at least the TL074, so have replaced both chips just to be sure.


I’m not sure if I should be proud or ashamed, but I can now SSH into my synth.

I managed to rectify the pinheader dumbassery and got it up and running this weekend.



Well, I put everything back on the breadboard and the lights haven’t gone out. Shame there’s no noise…


Have you tied the unused inputs to 0V?
CMOS - connecting unused logic gates

Yes, see the photo immediately above. I’m now wondering if I’ve knackered either the breadboard or the power header somehow. I’ve changed all the components, twice, and the none of the CD40106 will oscillate¹. All I get is a heavy ground hum when the POT is turned round to the bit where it should oscillate, nothing anywhere else. Pondering on wither something is not grounded properly when I think it is. The voltmeter thinks everything is hunky dory though…

Might strip the other breadboard, build the Kosmo Mini power header I have and try again.

¹ At least as far as I can tell, when prior to the frying incident, there was a distinct high pitched oscillation.

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Well, I could put this here too:

First mostly working version of 4-voice polyphonic additive oscillator with Arduino Nano.
Lofi and crunchy. Also quite buggy at the moment.


Definitely 50Hz? I’ve been (regularly) fooled by VCO not connected to CV, thought it was mains hum but it thought it was music. Maybe check that your control voltage is actually changing with a meter?

Finally got the new case powered and wired:


:joy: now i have some questions :wink:

I am wondering: are you daisy-chaining the power cables, daisy-chaining the distributor boards or are there more outlets in the panel to connect multiple boards?

I ran out of distributor boards and now started to daisy-chain module with the power cable…

What? The day after election day you go out and grab some signs and stick them in the garage. The next time you have a project that could use Coroplast, you’re set.

There’s a single PSU connecting to a nearby barrier strip, and for now a single bus board also connected to the barrier strip.

Assuming I don’t fill the case with 40 cm modules (I can’t, anyway, it’s about 70 cm wide) I’ll need to add a second bus board later, and it’ll connect to the same barrier strip in parallel with the first. The PSU can supply 1.5 A on each rail, so it should be able to comfortably handle the whole case.

(The panel mounted to the rails is just a power display, nothing behind it but a PCB with a power connector, two resistors, two LEDs, and three test points.)

Just don’t overdo it, those are thin wires.


You can do it this way :
= ← module
= ← Bus board
= ← module

Instead of

= ← module
= ← module
= ← Bus board

At least theoretically, it’s better.


I could have thought of that :wink:


And my 2nd Kosmo module (mostly) done! There’s still an issue to sort out, the final build oscillates much slower than it should, likely a wiring issue a multimeter will reveal, too tired to do it today.

Yeah, messy.

I repurposed circuits I already used in my CMOS synth. No need to tell me there are much better LFO plans available, I just wanted to try out making a somewhat original module duct taping existing circuits. I’m not expecting those early modules to be more than stepping stones and learning exercises.

A bit of hot glue will be applied to protect the ugliest part of the build — stripboard is unforgiving of mistakes. And since my layout had mistakes, and my circuit was just made for learning, I won’t share the flawed layout, but here’s the circuit if you wanna comment on it - not that anyone should use it:


I lacked VCOs to make more brrrrrrr.

My first tries with JLCPCB, and that was quite conclusive.

I think I have enough for a moment now.

Thanks to the community who helped me troubleshoot


You print you panels?