I had already built one, but it was an all-in-one version, and it was always a bit wonky, the old one is the dark blue on the bottom row, it’s getting dismantled soon. The one I built has the FM program on it. I’ll make the two others eventually!
I built it mostly as specified, but skipped the tuning knob (and disabled it in software), and replaced the single-supply op amp with a TL072.
I also skipped the tuning knob—I don’t really need one on a DCO.
Gave me some trouble—I still don’t have the skills to make a great prototype board layout on the fly, and ran out of space.
I experimented with adding this 3D printed lattice, to fasten the board with self-locking ties. The idea is good, but the pattern I used printed wrong, and I had to reinforce it. I’ll try out another pattern next build.
Also, I ripped out all the DYMO labels from my synth like a bandaid. I know what everything does! I built it. It’s not a mass-produced gadget. I want to gain mastery over it, I do not need labels.
Any different than your last buffered/unbuffered module, or just needed another one as you grow? Know you mentioned that you were changing your PCB approach.
Good question and I’m working on a blog post answer. The short version: Yes. The slightly less short version: Yes, always good to have more buffered multiples; but this is different from the one I already have (@CTorp’s design based on a circuit by Dave Jones): Its input impedance is 1M instead of 100k, which means it doesn’t turn a 1 V/oct signal into a 1.01 V/oct. And it’s based on voltage followers instead of inverting stages, which means it uses a lot fewer parts to get more outputs with unity gain basically guaranted instead of needing precision resistors or hand matched resistors or trimmers to achieve it. It also means it’s more vulnerable to overvoltage and would likely have trouble with inputs below -8 V. But I can’t see any way the former situation would arise with my synth, and the latter isn’t that big a deal — I can always use the other multiple if I really need such low input voltages, which would be rarely if ever.
Hmm… well, the intention was to have Offset on top and CV Level on the bottom. But that’s not what actually happened on the front PCB. The front PCB has only the pots and switches and a pin socket so would be pretty easy to re-do… but the panel would be even easier. I mean, it’d only require Dymo labels if I weren’t a little more fussy than that about appearance. And not even that if I weren’t a little more fussy about having accurate labels.
Only a small thing today. A simple debugging tool (mainly for logic levels): a resistor, one LED, 2 jack connectors, one printed case and a window cut from perspex. Could come in handy one day.
Passive splitter, mostly used to get eurorack-sized plugs from Minibrutes and Korg-SQ64s CV and Gate out to Kosmo. But also works as a splitter for big jacks if really needed.
Dual ADSR, now with leds. I didn’t even draw a schematic for this, it just minimal circuit for two Electric Druid ENVGEN 8C:s on a protoboard. And other channel seems to be a bit lower level than the other, I probably have wrong resistor somewhere. Oh well, doesn’t really matter. I’ll design a 10 cm (this being 15cm) version with maybe couple more controls and inverted outputs, and maybe normalized inputs and get a proper pcb manufactured.
A dual VCA with a AS3360. Basically the same schematic as the LMNC-version, but with added TL072 to have mixed output. This was a horrible build with much more time on debugging than building. And I managed to get a short and fry one potetiometer, which again was irritating to desolder. And when it finally worked, the left CV attenuator pot probably got shorted and it doesn’t attenuate at all.
Well, this will have a better version too. With a third CV in which affects channel 1 normally and channel 2 inverted. So I can for example have different waveshapes from same oscillator to channes 1 and 2 and have two different ADSR-shapes (from that dual ADSR with the normalization of gates) and have attack from one and then have the other rise to change timbre after a while. And the third CV to wobble between them slightly. And if In 1 and In 2 are normalized, this could be used as a automatic panning module with CV to only the third CV in and using both outputs.
I have been making a bunch of 2HP modules and I finally made a home for them in an old portable bar case. I gutted it, built in the 3D printed rails and a USB-C power supply, and some speakers I salvaged from a dead Bluetooth speaker.
External battery via USB-C only. I have some lying around, but I am not a big fan of messing with LiPos and such. The power supply I am using seems a little sketchy, too. It works (in that I haven’t blown it up yet), but it has a really big initial current spike from what I can tell. I should really have just used one of the Meanwell dual supply modules. Maybe one day I will learn.
This is the power supply set up I am using, along with a USB-C breakout board with the proper 5.1k pulldown resistors. 3D printed USB-C Eurorack power supply
Final module for my new case.
I couldn’t find a way to fit everything I wanted in individual panels. So back to a monster module, containing MIDI to Cv, mult, Env Gen, TAPLFO3D, dual VCA 3360 and the monotropa circuit.
I realised too late that I had made a mirror version of the module on the circuit board, so I need extra long wires to connect it all. (Not my favourite part of any build tbh and also main reason why it is still undone)
First post in a while. I got most of the DSP set up, the modulation sources seem to work, and made some amateurish modifications to the mutable SMR4 MKII filter to make it compatible with 3.3v. MIDI also works, but skips a note message every once in a while.
This filter sounds so good I built it twice! (once on the breadboard, once on the perfboard to clear off the breadboard ).
Now that the fun part is out of the way, it is time to take a bunch of switches and LEDs, and toil once again over a new UI.
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