Kassutronics Quantizer in Kosmo Format

The Kassutronics Quantizer module is the next module I am Kosmoifying. It should be a good addition to make the Turing Machine sound a bit more musical. Here is a rough draft of the panel layout:

Files up on github:


I am all in thanks , seems to be very tidy placement of pots and such ,love love new modules

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It never ceases to amuse me that we still use an icon of a floppy disk to indicate “save”.


I was thinking the same thing, and was pondering what could replace it. a micro sd card? a cloud?

I think we are stuck with that one as we forget the origin through the generations.

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I would use something like this for save:


I might use something like this, but it may not be as recognizable in some countries.


This is the first thing that came to my mind. My first exposure to the idea of saving:


Draft files are up on github.


Updated the git with the final graphics and the manufacturing files. I should have an order in for testing soon.

I also updated the panel graphics in the original post.


I have my first one built. Everything is working fine except that I can’t quite get it calibrated. I am maxing out my trim pots and can’t get where I need to be for 1v/o. I have swapped the resistor in the adjustment section of the circuit and got closer, but still not there. I sent Kassutronics a message to see if I am approaching that correctly, or if something else is wrong.

edit: I was able to get it to 1v/o by swapping out the 1k’s for 24k’s in the first output buffer circuit. I am not sure why I had to do that to get it to work, but it seems to be working great and tracking with a few mV for the full 10 octaves.


Have you measured the voltage on pin 1 of U3, the adjustable voltage regulator? Per the schematic it’s supposed to be about 5.3 V. If you needed to change the 1k to 24k, increasing the output stage gain from about 2.002 to 2.048, then that would mean the voltage on the microcontroller output pins after filtering is too low, which could be due to the regulator output being too low. That’s about a 2.5% increase in the output stage gain so that suggests even with RV1 adjusted as far as possible the regulator output is around 2.5% too low, about 5.17 V.

The regulator output voltage is nominally 1.235*(1+(47k+RV1)/15k) where RV1 can range from 0 to 5k, giving a regulator output range 5.105 to 5.516. The RV1 tolerance is ±10 V and if you used 1% fixed resistors the lowest maximum ought to be 5.395.

I’m making a few assumptions and estimates here so the numbers could be a little off. Still it sounds like the filtered PWM voltage is too low, and too low a voltage regulator output would be one way that could happen. The other way is if the PWM frequency or width is wrong, but if the software’s correct and the crystal is accurate I don’t see how that would happen.


I was able to set the regulator trim to get 5.34 V, but with the 1k in place, the lowest I could get the middle octave is 100 mV. I couldn’t even get it to 0 V with a 10k.

With my 24k in place, I had to trim the voltage regulator down to 5.22 V to get the +5 and -5 octave range. I am not sure if that is a problem, but it all seems to be working and tracking at the moment.

Adjusting the gain was the only way I could think to get the calibration correct.


Nice work! looks almost identical to the original, just big!


Hey! Great stuff again! I was wondering if you just made a single GND or if you distinguished between GNDA and GND as in the Kassutronics schematic. I am not sure if it really is a difference there or if they are connected at some point…
Also: any reason I could not use a nano instead of the pure 328p? There are already some other capacitors at VCC and AVCC, but this should not be a problem, right? All the other stuff is pretty much the same, hope :slight_smile:

Mine is all on one GND. I think GND is just the front board ground and GNDA is the back board ground on his design.

Kassu addresses the nano vs bare ATMEGA in the thread on modwiggler. It is mostly to avoid the on-board voltage regulator so it can use the precision regulator. You can work around that on a micro, but I wasn’t going to bother since I have no problem programming bare chips. If you did that, you could skip crystal oscillator.

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Also, I did have a little back and forth with him about my issue with the calibration, but we did not figure out what was going on there. It is still working fine for me with the different gain resistors.

I will eventually build another one to see if I get the same behavior, but I really need to build a new case, or three, first. My caseless modules are piling up.

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Cool! But if I use the 5V pin of the nano instead of the VIN I am bypassing the regulator, I think. Or could the unconnected regulator cause issues?

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Yes, applying 5v to the 5v output pin would bypass the regulator. Just make sure you don’t try to program it when the module is powered. Generally, you would put a diode in line to prevent an issue, but the voltage drop would defeat the purpose in this case.

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