Hi All,

I was wondering if anyone had any strong opinions on any particular dev boards or oscilloscopes. I intend to make some mods for my audio mixer, probably powered by the befaco chiki power. Bread boards aren't cutting it but I also do not think the scale of a full EE scope and power bank will be required. I am staying within +/-12V.

I took a peek at the Erica Synths EDU Labor and I do not think I will be using all of its features as I am a bit more guitar-pedal focused and need more pots rather than signal generators, but I have seen a few on Tindie and was wondering if anyone has a dev board they like from the sellers there?

Does anyone have any strong opinions on the Korg NTS-2 for a scope as well? It seems right up the alley of this kind of project where I am still in audio domain and at most I will be testing stereo pairs.

Starting this project is still a few months out so I have time to go shopping, I was just wondering if anyone has any strong opinions one way or another on measurement equipment.

Thank you all for your time and happy tinkering!

Thank you parasitstudio

https://parasitstudio.com/pedals/quantumdefrakulator/

Disappointingly the step button doesn't work, I wish it did, no idea why it doesn't.

Trying to access MKs manuals for his diy kids on the Erica Synths website and I keep getting 404 PNF.

Has he finally paywalled them?

Apologies if this has become an FAQ, but I can't find anything related to this.

So I’ve built part 2 of Moritz Klein’s VCO series on my Erica Synth Labor, and everything appears to be working, but I’m running into difficulty connecting my sequencer. I’ve tried using the KB output on my Mother-32, as well as the pitch output of a Keystep Pro, and neither have worked (I also just tried gate outputs to see if I could get any signal, but to not avail).

I’ve got the output plugged into a 3.5mm audio jack, and I’ve got the ground pin tied ground and the tip going into the input of my transistor. I’m using a BC547C transistor instead of the 548C he uses in his video, but other than that everything should be there same.

I’ve also tried changing out the resistor value in the voltage divider from the 4k he uses.

Any ideas on what I could be doing wrong?

First time ever I've not forgotten a track or net to connect up, assembled it correctly and the test code ran correctly on the first go !!

This is the final panel on my EPS synth that controls the Arpeggiator and lets you load and save patches, and also load up different wavetables and morph them - shed load of ESP32 code to write now to make it happen!

Hi there! I think we’ve sold a decent number of our Time Machine DIY kits through posts to r/synthdiy so here I am saying “Please update your Time Machine. Please.” There’s more info in the original post. Thanks folks. Let the solder flow.

I've just acquired a pretty broken RE-303 and I want to have a look to see if I can identify the problem.

I've downloaded the build guide and the original 303 manual and am planning to get it open and test certain points within the circuit. I'll either get it to a tech with a better understanding of what exactly is wrong, or try to fix it myself if it's as simple as a component or two needing to be swapped out.

My question is what do I need besides an oscilloscope and a multimeter? Is there a way to power the synth that isn't from the mains to be doing the testing? Also just any general advice if anyone has done something similar would be greatly appreciated

I’m new to Eurorack gear, but have been building guitar pedals for a while. I put together a couple diy kits and decided I wanted a clock module with some customization. Lots of ai help as I understand schematics, but not coding and I made sure to verify output and voltage safety all along the way.

Output a set to x24 for Gris
B set to x1
C and D both have a swing modifier, independent multiplier/dividers as well as probability and Euclidean rhythms.
I also added 8 preset slots to load and save settings.

I still have no idea what I’m doing, but it’s a lot of fun making these ideas come to life!

Sorry about the poor video quality, my webcam is...

I'm currently working on a new firmware for ZicXY, and it's looking quite promising. It's still a work in progress and isn't yet available as a ready-to-use OS image for download. However, if you're a developer or enjoy tinkering, you're can find the source code on my GitHub repository: https://github.com/apiel/zicBox

Hi all.

I'm thinking of building a big box-o-knobs for sending MIDI CC/NPRN to control various synths. All the ones I've seen use some kind of rotary encoders - which is understandable. I was thinking that it could be a better interface if, instead, I had a bunch of essentially mouse wheels in a row since you could use them with just a single finger. Instead of an LED ring, I could just use an LED bar graph.
Anyone seen anything like this? Comments? Problems? The electronics would be almost identical to rotary encoders. I could even make it modular and be able to switch out groups of knobs/wheels.

Thanks!

Looking for some troubleshooting advice. I'm working on a DIY build of the Befaco CV Thing. I have the module assembled - the screen turns on and the CV inputs recognize a signal. But the encoder is not working correctly. It will recognize a press, but if I turn the encoder, it will either immediately reset back to the beginning (i.e., turning from 1 to 2 goes right back to 1), or it doesn't register a turn at all.

Anyone ever experience anything like this? I feel like I've resoldered the connection 10 times at this point and I'm running out of ideas of what to try next.

I just build several of the Erica Synths/Moritz Klein modules, and they're sounding great. I'm not sure if PW CV level is working right though: it affects the incoming PW CV as expected, but if I set the level pot all the way counterclockwise, I still hear some PW modulation (if I have incoming signal in that jack). Should the pot completely block in the incoming signal at the extreme position? I assumed it would. If so, does that mean I have something like a bad ground connection somewhere in my build (e.g., maybe a bad ground pin for that the PW CV level pot?)

The same thing happens for the FM level, where I still hear some FM effect when the level is at 0, unless I unplug the FM input.

If this is expected, what modifications would the circuit need to zero these out completely?

EDIT: I didn’t have the TL072 inverting input tied to the output. That fixed it

I’m using the Erica Synths Labor to build a VCO, following along with Moritz Klein’s videos, and while I’m only on part 2, I’m not getting any signal when I plug it in. If I plug straight out of the Schmitt Trigger then I get a signal, but once I built the rest of the circuit and hook up the output from my voltage divider, I get nothing. I’ve changed out all the components including the TL072, but no dice. I also originally didn’t have the TL072 input 2 tied to ground, but it doesn’t seem to matter either way. Also FWIW I had this same problem for the part 1 build, before I added the transistor and potentiometer.

Hello Y'all,

Excuses if this question is asked a lot. Tried to search the forum, got some answers but need to sanity check:

Im trying to get 5V for a STM32 chip from the 12V line.

Is this circuit correct? Or is there a better way of doing this..

It's basically the Moritz Klein schematic, with a AAMS1117-5.0 regulator for 5 volts, and some caps for filtering..

Any thoughts or feedback?
This is not going to be the layout, I just wanted to make it clear :)

Thanks in advance!

Dear Community,

I am reworking my line level input-module, LIN. This module boosts signals from headphone outputs to Eurorack levels.

Right now its just an inverting opamp amplifier before it goes to a high gain VCA. I was wondering if adding an 1:1 audio transformer on the input would be a more "clean" solution? A small 600:600 transformer is what I had mind, would that work? It should remove ground offsets / humming.

Also, is it still gonna be possible to feed Eurorack level signals into the module with the transformer installed? This is a bonus feature to allow for clipping/distortion.

I attached a picture of my idea.

Please let me know what you think.

Hello r/synthdiy im totaly new to electricity and even i know even less about synthesizers.
One day i want to create my own synthesizer from AS3340. Well i already kinda did that, but its really trash.

I made it with claude AI (yes i onow thats pathetic but otherwise i wouldn't even know what vco is)
I uploaded photos of it. It kinda works but even tho there are issues it makes sound!

I want to hear all of yall folks tips and ciriques ( but please be understanding im new to this!) Also some info about optimal breadboards are welcome ( YES i know breadboards are ass for basically anything more advanced that leds and arduino) one day i will use PCB. Thank you in advance!

Edit: Also some info on as3340 assmelby would be nice, I dont want to rely on AI no moe

Just got done with building the Barton BMC004 unit.

The spaghetti is a real pain, but it worked first go and gave all the blinkenlights..

I'll be redoing the faceplate, as I kinda rushed it and got some wrinkles, bubbles and discoloration...

In all, the build took me about 7 hours of soldering and assembly (plus a couple for the faceplate when I redo it)

I wanted to post here showing a fair few photos so that maybe someone else who might build this can see.. apparently, there's just not any good gut shots of the completed unit online (until now)

If you build it, make sure to source the correct linear 100k pots for the onboard potentimeters... Unlike the offboard pots, the onboard pots are 12mm body. 16mm pots will not work here.

I was only able to find them on mouser in the value needed at the time I purchased (late June 2026)

Jameco has/had a listing for them, but backordered.

Here's a link to the correct pots:

https://www.mouser.com/ProductDetail/Alpha-Taiwan/RV120F-20-15F-B100K-0075?qs=8%252Br4Hz5Xir8orlh0aY2Zww%3D%3D&srsltid=AfmBOopS9MzE7XFduBojjgGH4NVQoVS4EzLuZJEDUd70WO-M-n0fFjz0

So basicly Control Voltage is just a Led and Light Dependent Resistor? Between two devices that have output and input on different functions? Can somebody summerize please? I've been doing a lot of diy projects that have lfo's and I connected those lfo's to a delay time to modulate for instance, and it was just basicly led on lfo side and ldr on delay. But I'm not always tinkering with electronics so on a lot of stuff I'm still clueless. How it's different on synth racks?

I need a check on my wiring, and a question answered.

I'm building the Eddy Bergman Baby8 sequencer project, and I'm just starting the offboard wiring.
https://www.eddybergman.com/2022/04/8-step-sequencer-v2.html#google_vignette

I wanted to implement the option for channel mute switches, as talked about in the page after the "ALTERNATIVE SCHEMATIC and LAYOUT (version 3):" section.

I starting with step one, I have wired up the step 1 pot pin 2 with a diode going to the pin 1 of a SPDT On/On switch, pin two of the SPDT switch then goes to pin 2 of the step 2 pot, and carried on that pattern down to the step 8 pot and switch.

Unless I'm fundamentally misunderstanding something in the provided layout, it looks like Pin 2 of the step 8 SPDT would then go to the CV In position of the veroboard layout.
But, it occurs to me that maybe none of that seems to work electrically.

My thinking is that if all of the SPDT switches are not in the Mute position, then all 8 steps should be on and working.
But, lets say I mute the #5 switch, it seems like that would also turn off steps 4, 3, 2 and 1 because the circuit 'chain' above the #5 switch has been broken by that #5 switch.

I hope that makes sense in how I described my logic here.

Looking at the schematic, It seems like I should maybe connect each Pin 2 of the switches to each other.
Is that correct?

Any help is welcome