MIDI to CV schematic 3/30/26
I have completed a schematic and stripboard layout for the MIDI to CV module. It's is utilizing Analog Output's original schematic, but since his was a little limiting for me, I've taken his schematic (and eventually his code) and added two new CV outputs and new gate and trigger outputs. With these outputs I should be able to run two voices from my computer (or other midi divice) as well as one voice with a hell of a lot of modulation.
Schematic 1/2
Schematic 2/2
My next step is to order the parts and then get soldering, some folks on the LMNC forum say it should work so I am going to chug forward. I'm not gonna lie though, cutting all those jump wires is gonna take FOOORRREVER, and I am not looking forward to it. I think after this, if there are any larger projects like this, I might order a PCB cause yeesh. Then after that, I get to learn how to code the Arduino, cause sadly, I have made this not a copy and paste, like an ass. So well see.
There will probably be some edits to this in the near future as frankly, I have no idea what I'm doing.
Next Plan 3/24/26
My next goal is to make a MIDI to CV converter as it will make Vellum more of a controllable instrument rather than a 4 on the 4 beat machine (as good as it sounds). This will also allow me to avoid troubleshooting the VCO and the LFO for now. This will be a whole new endeavor as I'll need a micro controller of some kind and I've never used one before so lets go.
Low/High Pass Filter Finished(ish) 3/19/26
Today I finished the filter for Vellum. It is a low pass filter with a high pass switch designed by Look Mum No Computer using the LM13700 chip, based off of the Rene Schmitz schematic, based off the Korg MS20 synthesizer. In other words it is called the LMNCRSMS20LM13700L/HPF. IT SOUNDS WET!!! Playing around with it the first time at midnight tonight after finishing and its the first time that Vellum has sounded... good. It definitely sounded great and I cant wait to throw it through some big fuck off speakers. The resonance (which actually isn't working as intended at the moment) is KILLER. It can definitely be used to keep a beat, and once I can run some sort of sequence through this thing... oh yeah.
The title says that the module is finished(ish) because of a few things I have not been able to get done. First: I need to add the standups and drill holes so the board isn't all floppy. Second: I need to rewire the LED's so they are actually doing what they're supposed to do. I currently have them wired in series, they should be wired in parallel with opposite polarity. and Third: I think I need to spin the High/Low switch because I think its backwards compared to the panel, but Ill fix the LED's first in case that is what's making the sound weird.
My next module for vellum is a MIDI to CV controller. I want to be able to sequence it with StrudelREPL but I need a way to go from ones and zeroes to voltage. That will take a bit of research to figure out what I can do, and how complicated I need/want to make it. In the mean time, I have a few things I need to get in order.
- Get the pulse wave to work on the VCO, I really hope its just the TL072 chip being finicky, otherwise this will be a pain
- Fix the blue channel on the LFO and get the lights working (more blinkies is more gooder(and actually helpful))
- Add a passive attenuator to the Evelope Generator and paint the panel.
- Expand the mixer to use the other half of the panel
- Find some aluminum sheet thicker than paper thin cause I am sick of these panels being so damn floppy.
Vellum Introduction 3/15/26
In mid 2025 I stumbled upon modular synthesis via a youtube short featuring Switch Angel playing a large modular synth. It was a big giant thing with knobs and wires and switches and dials making etherial sounds. I was obsessed immediatly and started to research how to get my hands on one of these. Everything was pointing to me having to spend $1000 minimum to make some bleeps and bloops, something that I cant afford at the moment. I then found Look Mum No Computer and his sumper simple DIY series. In early 2026 I began construction of my synth in ernest. I started with the case, powered by a frequency central DIY board and the Super Simple mixer from LMNC. Then I built the LMNC CEM3340 VCO, the Sound Bender Tripple LFO, and the LMNC AD/AR envelope generator.
The aesthetics of the synth are heavily influenced by the Book of Kells and other illuminated manuscripts. Vellum is the paper like material made from animal skin that those texts were written. The panels are intentionally an off white color to mimic the texture, currently I am using sharpies for the drawings but the process blows so I will be looking for other ways to "illuminate" the panels. Gilding with a bit of gold leaf would also be so much fun. A friend of mine is planning on painting the side panels in a Bosche-esque style. When I feel like it, which hopefully will be soon I will be adding knobs of all sorts of colors to the panels.
There is obviously a long way to go to make this a functional and musical instrument, but its been a great project none the less. My to-do list includes fixing the square wave output on the VCO, filling out the other side of the mixer, fixing the LED's and the blue channel on the LFO and drawing on the ADAR. I don't have much electronical know-how so the troubleshooting process is difficult. Future modules include a low pass filter that I am working on now, a MIDI to CV converter, a sequencer, a VCA, and maybe a few other sound modulation modules.
Reel to Reel Nonsense 3/11/26
I recently stumbled upon this 1964-ish Voice of Music Courier Tape-o-Matic Model 726. Thankfully the power supply worked, and the only major repair was replacing a small belt on the connecting the motor to the reel pully.
There are a pair of breaks that stop the reels. The hooks on these have disintegrated over time cause the reels to act a little jumpy resulting in weird feedback when recording and an undulating sound when playing. I replaced the hooks with some steel wire I had and some super glue. Any purists look away now.
