RommudohMay 25, 2025
This time my #soldering was a fail. This is supposed to be a #keyboard controller for playing my #StackSynth but the sample and hold part needs rework. The output voltage keeps rising. At first I noticed that I used a ceramic #capacitor where I should've used a polymer one, but this bodge didn't help. Maybe the #TL074 are out of spec (most likely fake ones but worked fine in the other modules) or the FETs are bad...
The keys will be attached using a stereo 3.5mm audio jack, and will be extendable like my perfboard version.
#diysynth #synthesizer #sampleandhold
Show threadRommudohMay 2, 2025
And here it is. The boards arrived today from @aislerhq so I had to solder it immediately and it sounds nice. Even my wife commented, that my annoying experiments start sounding acceptable.
#soldering #StackSynth #VCF #diysynth #synthesizer #LM13700
RommudohApr 15, 2025
I'm planning another module for my #StackSynth - a #VCF based on the #LM13700 and the Skull & Circuits VCF-3: https://www.skullandcircuits.com/vcf-3/
I already designed the #PCB in #KiCad but wanted to test it on a solderless #breadboard first. It works fine, so I ordered the PCBs.
#diysynth #electronics #synthesizer
VCF-3 – Skull & Circuits

RommudohMar 31, 2025
One of the final modules for my #StackSynth project: the #noise generator. It outputs white, blue, and pink noise and uses a #3904 and a #TL074 with a lot of resistors and a couple of capacitors.
It is based on Moritz Klein's video: https://youtu.be/0yB_h_wFkh4
I prototyped it on solderless #breadboard and then designed the #PCB in @kicad and let @aislerhq manufacture them again. It turned out quite nice and sounds great.
#soldering #diysynth #synthesizer #KiCad #pcblayout #MoritzKlein
Designing a white, pink & blue noise generator from scratch

YouTube
Show threadRommudohMar 26, 2025
And here is the #StackSynth power supply board done. It provides dual rail +/- 12 Volt from 12 Volt AC. Stable for at least 300 mA. The diodes D1 and D2 get a bit warm, though. I'll have to see how it performs with my modules attached.
Again, boards were manufactured by @aislerhq and arrived together with the VCA.
My StackSynth tower is almost finished so far. There will be a Noise module coming and maybe I'll add another LFO.
#soldering #diysynth #synthesizer #powersupply
RommudohMar 24, 2025
Finished #soldering another #StackSynth #diysynth module, an important one: the #VCA - together with the ADSR, it makes the output sound much better.
Again, boards were manufactured by @aislerhq and they look nice.
I noticed that I didn't have any 2MΩ 0805 #SMD resistors, but found a couple of larger 1206 2.2MΩ ones in my recycle bin. They don't fit perfectly, but should do until I have the proper ones.
#synthesizer #LM13700 #TL074
Show threadRommudohMar 17, 2025
Finished #soldering the #StackSynth #VCO after the missing resistors arrived today. The tuning knobs are a bit close for my taste. The next revision will have a wider gap between.
After tuning it to roughly 1 Volt per octave, I tried it with my #sequencer. The test setup only included VCO, LFO, and mixer, though. The VCA will be the next board.
https://makertube.net/w/xwhPj4tAb2BdmPDmQuVakv
#diysynth #synthesizer
StackSynth VCO test

PeerTube
Show threadRommudohMar 16, 2025
As announced, I finished the buffer today. Also, I soldered all #SMD components to the #VCO board that I already had. The two missing resistors will follow when they arrive.
It was fun and went better than my previous attempts, since I used a smaller tip.
#diysynth #StackSynth #soldering #synthesizer
RommudohMar 15, 2025
Three new boards for my #StackSynth arrived from @aislerhq yesterday. They are buffer, #ADSR, and #VCO. The VCO is the first with #SMD components on the bottom side. Two resistor values are missing in my SMD collection: 30k and 68k. I already soldered the ADSR and tested it. The buffer will follow tomorrow.
#diysynth #soldering #synthesizer #envelopegenerator
Show threadRommudohMar 8, 2025
a longer demo of the #sequencer. I play around with some controls and have replaced the mixer and LFO with the available #StackSynth modules, mixing sawtooth and triangle waveforms of the perfboard VCO (will be replaced by one of the next StackSynth modules).
#diysynth #synthesizer
https://makertube.net/w/1SoLv9g8bagtud34Muejjk
longer demo of step sequencer

PeerTube