It is a VCA/Distortion module 
The signal runs through the EARTH and is then amplified.
The conditions of your environment play a big part in how this distortion sound.
The box of earth kinda acts like an inductor as well.
The original concept was created by Martin Howse who makes a line of modules called ERD.
He also makes digital modules that are fascinating with “PLAGUE CODE” to really mix things up!
A little bit about Martin
I think my significant other fears this is how I’ll turn out if I spend too much time tinkering in the garage to the detriment of our social life…
Thats one way to ground your synths.
Roundhouse by @sebastian (Befaco Kickall in Kosmo format)
Pulses for the Halting Problem by @sebastian
(derived from Kosmo Turing Machine by @BenRufenacht)
I have not considered 3d printed nuts on the jack sockets before!
Hmm not a bad idea, good for keeping track of ins and Outs… Also some tpu knobs. Hmmm makes me want to sort my printer out XD
Made a stupid mistake with my vca that cost me some time, accidentally added an extra unused row on my stripboard which meant two voices weren’t passing through to the mixer.
Now I’ve got that all working, on to the filter and lfo today.
It’s (almost) done…
Halting Problem + Volts + Pulses by @sebastian
Today’s build progress is completely synth-unrelated… How does one set off ~80 confetti streamers, when they’re positioned ~11m high on a moving platform, out of reach to swap them, and without spending an absolute fortune on commercial launchers?
Well, with a whole bunch of relays. Now to solder connectors to 6 20-conductor cables…
Please post a video once in action!
Ok, last hurdle and bar one tl074 that I put in the wrong way round (…) everything works as intended.
I have an lfo going to the filter and pulse width mod input, it’s on an intensity pot for the PWM and a full-off-half intensity switch for the filter. The filter envelope gate either comes from the first note’s gate or an OR gate, which adds some interesting expressive effects. LFO is the standard system 100 version, filter is an ms20. Might amplify the filter envelope, will see how I get on.
Felt like a lot of work but I’m happy! Got some new verified stripboard to paste now too.
Finally some success with 8 voices test of the Pico DCO, my assumption about the shift register using PWM seems to be correct and actually using SPI instead does not use PWM, so you have the full 16 PWM channels available to generate 8 voices. I used an 8 channel DAC to generate the gates (very wasteful I know, the 12, or 14 bit versions would also do the same as this 16 bit DAC.) I found that GPIO4 was not available as it was being used by the SPI, so SPI takes 4 pins plus 1 extra per DAC. But moving to the unused GPIO0 which is the TX of the MIDI does work for PWM.
So for my design with FM inputs and octave switching I had to use the YD-RP2040 Pico clone as it has extra pins available. But I think for the standard Pico DCO by Yannes it should be possible to get 8 voices using the DAC.
Also note that it is possible to drive a shift register over SPI so it may not be neccessary to sacrifice a DAC, but I have not tested any SPI shift register libs yet.
I’m an idiot…
****** What just occured to me is that you could just add another PICO purely doing the gate outputs, link the two MIDI in’s together like I did in my Poly KIT Duo build and the second Pico can generate your 8 gate signals, drive a DAC for CV and another for velocity, no need for squeezing the most out of the pins and you could probably have enough pins left over to control the MIDI channel ******
synthcube has the mutables module tester case for $49 usd
I feel silly posting this, because I’m surrounded by clever people here and I’m… not but the one thing I know is that the community that has developed here is friendly enough to humour me!
My current project is the sequencer. Four voices of 12-bit audio for drum/percussion samples together with three trigger outputs (they’re wide open gates at the moment - I wanted to know the hardware would behave itself before going further - hence the horrible beat). It’s all coded in CircuitPython, which is a lovely environment.
Blog post about it here where I waffle on excessively, as I am known to do.
Looks neat. Are you using on of your EuroPi’s for this?
Nah, I’m still waiting for some parts to make them (the through-hole opamps are hard to get in small quantities). This is based around an Adafruit NeoTrellis M4, which provides most of the functionality, and an I²C GPIO extender for the hardware integration. To get a 5v trigger output from a 3.3v microcontroller/extender, and to provide a nice bit of buffering, the output lines are used to switch a CD4066B chip I had on hand - it works perfectly, very pleased!
Ah, okay, sweet. I have on of those I plan to build something with, but was probably going to code it up in Arduino. I’m still thinking about whether I want to make it do any synth stuff or just a multi track midi sequencer/clip launcher type thing.
