Korg Monotron Euro Module DIY

lionelfischer · Post by **lionelfischer** » Thu Dec 16, 2010 11:06 am

I would like to send a Korg Monotron to someone who can make it into a Euro module for me. Anyone done this yet? // Anyone want to be the first?

mantiwhore · Post by **mantiwhore** » Thu Dec 16, 2010 11:07 am

same here, same here!

JP · Post by JP » Thu Dec 16, 2010 11:09 am

+1 (if someone did this for $XX.xx as a conversion service, I suspect they'd be pretty busy)

richard · Post by **richard** » Thu Dec 16, 2010 11:31 am

ersatzplanet · Post by **ersatzplanet** » Thu Dec 16, 2010 11:38 am

I could easily design a front panel for it if I had one to take measurements from. The main problem would be how to mount the "keyboard". I would imagine it would have to be vertical to save HP. The unit runs off 3V too (2 batteries) so that would have to be sussed out and a circuit designed to convert the +12v to that (unless it actually can be run off of +5 which would make it much easier). The project would be pretty simple otherwise. I have never seen the guts of the unit but if the jacks are PCB mounted than they would have to be replaced, no problem there either. I probably could make a front panel express design and let the plans out for free if I could get my hands on one for a while. Someone could dis-assemble one and scan the front panel with a decent ruler next to it and I might be able to scale it accurately enough to make plans from that. Also scan the guts for possible PCB mounting holes etc. - or you can send me one! If I go and buy one I will have to be charging for the panel plans!

-James

ersatzplanet · Post by **ersatzplanet** » Thu Dec 16, 2010 11:45 am

I guess KORG really want people to hack this little guy - I just had the full schematics emailed to me right off the Korg Monotron web page - for free.
-James

bkbirge · Post by **bkbirge** » Thu Dec 16, 2010 12:16 pm

Is this an SMT design? I guess so since it's so small? But they want to have it hackable? I'm tempted to pick one up just to hack but all my skills are through hole type (heh).

Tim Stinchcombe · Post by **Tim Stinchcombe** » Thu Dec 16, 2010 12:34 pm

Something I'd like to have a go at, but far too busy on other stuff at the moment. Biggest headache I see is the power: 3.3V or so from the batteries is boosted to 5V by a DC-DC boost converter - so far, so good. Then they go and make a 1.35V reference voltage, and the signal swings about this (i.e. it is 'ground' to the Monotron). Thus to interface to normal signals referenced to our usual idea of ground (0V), the Monotron would need to be powered by +3.65V, -1.35V supplies, and all ground connections on jacks etc. isolated appropriately from the (now) -1.35V rail.

And that's about as far as I've got with it. However, I wouldn't be surprised to learn that there is some sort of 5V regulator chip out there which can be floated, i.e. we set some sort of V ref of -1.35V to it so the 5V gets pushed down to become the required +3.65V, -1.35V. Then other than the ground isolation, it would be really easy. Unfortunately I suspect the time spent searching for such a regulator could be very large...

Tim

Tim Stinchcombe · Post by **Tim Stinchcombe** » Thu Dec 16, 2010 12:39 pm

bkbirge wrote:Is this an SMT design?

Yes, most of the discretes are 0603. Some early snaps:

http://farm4.static.flickr.com/3610/455 ... 2aec_o.jpg

http://airvariable.asablo.jp/blog/2010/04/25/5041601

Tim Stinchcombe · Post by **Tim Stinchcombe** » Thu Dec 16, 2010 12:49 pm

ersatzplanet wrote:The main problem would be how to mount the "keyboard".

I'd go a step further and just say chuck it! Surely the whole idea of modularizing it is to have proper 'CV control', so who'd want the keyboard...?

Or perhaps stick a much longer cable on it (it is separate from the main PCB), so that it could be plugged in a la traditional 'ribbon controller'

Tim

Soy Sos · Post by **Soy Sos** » Thu Dec 16, 2010 1:06 pm

Why not just continue to run it off batteries and do the mods hacking in CV to pitch, VCA etc...... ?
It can sit next to the modular and still continue to function free-standing if you like. Maybe that might not be such an all consuming task for a clever builder who'd like to offer a conversion service. It seems like every time there's talk of converting something not designed to be a euro module to a euro module, the stumbling block is that it's too much of a pain in the ass to get it to work with +/- 12 and to get the damn thing to fit properly.

I went through this with a small Folktek instrument that I should have just left the hell alone.

transferpoint · Post by **transferpoint** » Thu Dec 16, 2010 1:06 pm

I was thinking the same thing, I'd like one too. I know you can add CV inputs to it as well.

I'd buy a front panel or kit or possibly send it out for a mod.

Low-Gain · Post by **Low-Gain** » Thu Dec 16, 2010 1:32 pm

i'd be willing to help out in such a project.

I've been meaning to mess around w/ the Monotron for a while. I'd drop the keyboard concept all together and just toss the CV/Gate mods for control. Just treat it as an all in 1 module w/ some cv control inputs, audio routing, etc. You could probably get it into 8-10 HP depending on the amount of controls you wanted. actually 4-8HP if you went w/ a more minimal approach.

I gotta buy first though. hahaha

Kodama · Post by **Kodama** » Thu Dec 16, 2010 1:39 pm

I like the idea of making a breakout cable that you plug into the module. The module handles the breakouts and level adjustments as needed.

bkbirge · Post by **bkbirge** » Thu Dec 16, 2010 1:41 pm

I'd say keep the keyboard and add cv OUTS as well as ins.

richard · Post by **richard** » Thu Dec 16, 2010 1:41 pm

I agree with Tim that the keyboard is really of no consequence

(unless you want your Barbie dolls to play with it)

Bird Of Paradise · Post by **Bird Of Paradise** » Thu Dec 16, 2010 2:32 pm

ersatzplanet wrote:I could easily design a front panel for it if I had one to take measurements from. The main problem would be how to mount the "keyboard". I would imagine it would have to be vertical to save HP. The unit runs off 3V too (2 batteries) so that would have to be sussed out and a circuit designed to convert the +12v to that (unless it actually can be run off of +5 which would make it much easier). The project would be pretty simple otherwise. I have never seen the guts of the unit but if the jacks are PCB mounted than they would have to be replaced, no problem there either. I probably could make a front panel express design and let the plans out for free if I could get my hands on one for a while. Someone could dis-assemble one and scan the front panel with a decent ruler next to it and I might be able to scale it accurately enough to make plans from that. Also scan the guts for possible PCB mounting holes etc. - or you can send me one! If I go and buy one I will have to be charging for the panel plans!

-James

I'll send you mine! I would love to have this thing converted, it's just been sitting around so if you want to use it as your guinea pig I guess PM me?

Bird Of Paradise · Post by **Bird Of Paradise** » Thu Dec 16, 2010 2:35 pm

bkbirge wrote:I'd say keep the keyboard and add cv OUTS as well as ins.

+1

Would be pretty cool if you could use the keyboard ribbon as a cv controller within your rig...

phono1337 · Post by **phono1337** » Thu Dec 16, 2010 2:55 pm

if you were to bother doing this you'd want to take care of the crappy headphone output also

ether · Post by **ether** » Thu Dec 16, 2010 3:48 pm

How about going the other way and making some kind of miniminimini-polyphonic-cv-controlled-monotron-modular, just out of hacking multiple monotrons together? If someone could work out CV in we could use one tron's ribbon to play many of them at the same time???

That'd be worth

at least!

lionelfischer · Post by **lionelfischer** » Thu Dec 16, 2010 4:14 pm

ether wrote:How about going the other way and making some kind of miniminimini-polyphonic-cv-controlled-monotron-modular, just out of hacking multiple monotrons together? If someone could work out CV in we could use one tron's ribbon to play many of them at the same time???

That'd be worth at least!

whoa

lionelfischer · Post by **lionelfischer** » Thu Dec 16, 2010 4:15 pm

i should have been more clear. i was in it for everything but keyboard to be modularized.. but all these ideas and additional mods are cool as hell.

4mspedals · Post by **4mspedals** » Thu Dec 16, 2010 4:24 pm

This guy added CV jacks to his:

http://www.dinsync.info/2010/06/how-to- ... otron.html

Kodama · Post by **Kodama** » Thu Dec 16, 2010 6:16 pm

Yeah I like how Din Sync used a breakout cable, seems the best way to roll.

Damn that filter sounds nice!

lionelfischer · Post by **lionelfischer** » Thu Dec 16, 2010 6:44 pm

I'd be totally into JUST the filter being turned into a Euro module, with CV control obviously, but just a real simple thing, if that made it any easier/faster/cheaper

MOD WIGGLER

MOD WIGGLER

Korg Monotron Euro Module DIY

Korg Monotron Euro Module DIY