Finally I made Ondes Martenot like CV controller for MS-20 mini.
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I'm very interested in the Ondes Martenot but it is very hard to find instrument and also it is very expensive, naturally no place to try it. Also making real replica of Ondes Martenot is, maybe very difficult for ordinary people.
However I was looking for the info about DIY Ondes by internet, I found some peoples made their own Ondes like controllers for their instruments. It seems that making CV controller for analog synth is not so difficult.
So it's a time for me too.
About the Ribbon controller, I built it on the 1x6 (3 feet) wood board, it has four pulleys to make string loop and a pulley for 10 turn potentiometer that make pitch CV.
I used "Door Wheel" as a pulley for this project. It is very cheap (less than 100 yen each )
but works fine.
However this aluminum pulley for a potentiometer was little bit costly price.
I used 1k ohm pot because I already keeped it but maybe 5k or 10k is reasonable value.
No extra space for new keyboard then place it on the KROME 88 temporary.
Basic electrical connection is like this, 9V battery operated CV device for analogue synthesizer.
This gate ( trigger ) is just for MS-20, KORG logic ( note on = GND ).
A bird is eating a worm, or a "Touch" lever for this project.
I decided to use 9V battery and 5V supply for CV then problem is the circuit for the "Touche" controller.
I made this "Touche" device, as a lever, using ordinary potentiometer. The lever moves among very limited angle, about 30 to 45 degree then I got very limited resistance value with it (about 10% to 15%, 1 ~ 1.5k of 10k pot. for example ).
Then I designed this circuit for the Touche lever. I used 10k pot. and ...
... it can control from almost 0V to nearly 5V like this.
quite messy built but works fine.
Very different from original "Touche" but this lever is the Touche for me :-p
"Gate" or trigger is made with micro switch driven by the Touche lever.
1st floor is for 5V regulator and 2nd is for the Touche circuit.
Outputs Pitch, Touche and Gate CV.
Then patching chart for this controller.
This controller outputs Pitch CV as Oct/V and MS-20 can receive it at "FREQ" jack ( not "VCO1+2 CV IN", that is for native MS series CV keyboard or Hz/V system)
"Touche" can use anything, just like a expression pedal, not only for the volume control with VCA but also for controlling VCF or any other parameter if you like.
