Korg Monotron Euro Module DIY

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Common Wiggler
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Post by matic » Thu Nov 21, 2013 8:57 pm

Hey RTB,

a little confused at what you mean when you write the cv output is not yet configured. I assume you mean on the theremin? what type of configuration will you be doing?

As far as voltages are concerned, they will be fine assuming you have modded the monotron..

when you say, what kind of drop per octave, if you think you will be able get 1v/oct, I highly doubt that will be the case, I am just guessing here, but considering the power rail is 3 volts or so, anything above 3v will not provide additional octaves/semi tones.

I apologize if I did not understand your question..

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Post by RTB » Fri Nov 22, 2013 12:50 pm

Hi matic,

Sorry about the confusion over the CV out: it's a digital theremin and the software bit to configure the CV output hasn't been written yet. That's what I meant.

If I read your post right, do you mean that the CV of the Monotron should be between 0 and +3V?
If so then that is usuful since it means I can try for a CV output of (3/5)V per octave and see where it takes me!

Thanks again for the answer.

Oh, and yes, I have modded the Monotron.

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A Certain Wiggler
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Post by sines » Fri Jan 03, 2014 11:45 am

Scanned through the last 13 pages and still a bit confused.
How did anyone mod the Monotron to work off a Euro 5V or 12V rail [using a 7805]?

if you could provide diagrams / schematics that would be awesome.


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Post by Mdashdotdashn » Sat Jan 04, 2014 7:07 am

If you look at the diagram

http://www.korg.de/fileadmin/_korg/_pro ... rlagen.jpg

In the bottom part, there's the VCC/TP5 pin. This is the 5v power supply. When ran off batteries, the circuit to the left of it generates 5v (that the monotron uses internally) from the 3v of the batteries.

You can however not put batteries and directly power the monotron from that pin (it is labeled on the board itself). Don't combine the two though.

I've successfully powered my monotron mod from the 5v pin of a teensy and it works out of the box.

Hope this helps,

more stuff here

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Paradigm X
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Post by Paradigm X » Thu Jan 09, 2014 9:55 am

So, i accidentally (well duh) lifted the gate pad while soldering on the wire :cry: :cry: :cry:

Looking at the schems, it only attaches to pin 10 of IC2, which looks even harder to solder too.

Anyone who knows more than me, ie anyone, have any bright ideas please?

Also, been thinking about using the ribbon to control the filter, seems its a voltage divider, could cut the trace and rewire it to the filter tp?

Many thanks

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Monotron Duo?

Post by loopdokter » Tue Sep 16, 2014 10:33 pm

Has anyone worked out the MIDI or CV/Gate for the Montron Duo? I've got one sitting here that's sadly not being used due to it's lack of being able to be thrown into the mix with my CV/Gate gear or my MIDI stuff.

Common Wiggler
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monotron directly in CV gate bus (with doepfer case)

Post by fg » Wed Dec 10, 2014 5:05 pm

voilà works perfectly with a midi to CV


Learning to Wiggle
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Post by newnoise » Fri Mar 13, 2015 4:05 am

Hi everyone,

I finished modding my Monotron, thanks to all your great posts! I'm really satisfied with the results!

From my Monotron I removed R11, to solve the gate influencing pitch problem and because now I have a nice "droning" Monotron!
My next project is my Monotron Delay. From the schmematics I think that removing R14 at the the Delay should have the same effect than removing R11 at the normal Monotron. But I'm far from being an expert on this and my SMD soldering skills are weeeak! So try & error removing it is not really an option.

Can anyone confirrm my assumption?

Thanks a lot!

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Post by captainhooke » Wed Apr 01, 2015 10:03 am


very very interesting and cool stuff here. i'm gonna use this thread as a tool to make something like the thing in my image attached. i have the ideas, but lack the knowledge to do so. will read this thread carefully and luckily i have a more capable friend helping me out.

what do you think, is it possible? or am i missing something very important?

will post my progress here.


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Wiggling with Experience
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Post by Amer1231 » Fri Apr 17, 2015 2:15 am

If someone could sell the modded modules for the peeps who cant solder and stuff :nana:
On a side note, did anyone check this?

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Happiness Forever
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Post by Happiness Forever » Sun Jun 21, 2015 9:57 pm

I am in the same boat. I have both a Monotron and a Monotron Delay. They're fun. Would love to get em into Eurorack.....
Someone? Anyone? Bueller?
:help: :zombie:

Live Large, Live Often.


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Post by widgetoz » Wed Nov 09, 2016 8:21 pm

Go to RhythmActive in Australia, they have a front Panel and a Kit to mount your Monotron in to a EuroRack. Search for MODATRON

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Common Wiggler
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Post by daynehacks » Wed Nov 09, 2016 8:33 pm

What about the Pulp Logic kit? Has that been mentioned?

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Post by bujbot1 » Fri Apr 21, 2017 9:56 am

Wanted to post this incase it helps someone out in the future.

Last week I modded my monotron delay into an eurorack module. I removed the touch strip a year ago to make into its own module so I could interact with my synth more and had planned to do this since then. I have 2 pots; 1 for controlling the freq/voltage and the other to drain/add a little to the CV coming in to be able to tune it. CV in for pitch, gate and cutoff, aux in and audio out. I also added a switch to turn the speaker on and off.

Something big to note ... I'm pretty sure there is something wrong with my monotron delay. Applying the simple Dinsync method got me nowhere on any of the test points. Maybe the delay is that much different than the normal monotron, or mine is a bit messed up. So THIS MIGHT NOT WORK FOR YOU!!!

Here's roughly what I did (not the best description, sorry, it's all shrink wrapped up now too):
R14 removed (R11 on mono)
amp upgrade
for pitch: 180k on CV in. Goes through 1M pot (controls freq/v), meets 500k attached to 10k pot that is between +5 and GND (for tuning)
gate: diode to Vbias (i found if the CV was around 0-0.5v the gate would be connected)
10k (or 100k) to ground (i forget which).
100k resistor to test point.
Cutoff: diode to protect from swinging LFO’s affecting pitch. 180k to test point.

Sounds like this:
https://soundcloud.com/user-736801819/2 ... -fingers-2
https://soundcloud.com/user-736801819/2 ... -fingers-1

Looks like this:

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Re: Korg Monotron Euro Module DIY

Post by Alextrem » Tue Jan 12, 2021 9:16 pm

Hello,look at this mod, so it works great
what do you think about that pnp bc557, i'm use a bc 559B philips and so god, i'm use to rampage for CV and adsr befaco it works very well.
what is really cool is the filter controller which works without the vco

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