[sdiy] Building an Ondes Martinot or French Connection stylecontroller?

[Ken Stone]

The string slip problem is solved by anchoring the string at the ends to the
pulley. It is not a continuous loop, but rather a long string (3 times the
length of the travel + spare to cover the remaining distances between the
pully and the playing area), with a one length wound on the pully, one
length along the keyboard, and one length returning from the other end of
the keyboard to the pulley again. Usually one end was terminated in a spring
housed within the pulley itself.

Ken

>I've built a few simple portamento controllers, and I want to build a
>sort of Ondes Martinot controller (Sort of like the Analogue systems
>"French connection" controller -
>http://www.analoguesystems.co.uk/Reviews/fconnection_review.htm). I
>mean JUST the portamento string-ring interface, not the keyboard
>interface. If nobody's seen one before, here's a nice video explaining
>one.. http://youtube.com/watch?v=ybYIhomm5KM
>
>I've never actually seen the inside of any of these controllers and
>I'm sort of curious as to how they might work. I'm wondering if anyone
>has seen inside, or know exactly how they might work mechanically?
>
>My first guess would be to have the string wrap a few times around a
>pulley wheel attached to a 10-turn potentiometer (or a geared down
>single turn pot, to avoid having a pulley wheel with a circumference
>as long as the actual playing field area). I'm wondering if maybe
>either of these controllers came up with a way of avoiding the string
>from "slipping" on the pulley over the course of time, or if just
>wrapping a string around a pulley multiple times would cause enough
>friction to avoid this (I'm reminded of old FM tuners, which I THINK
>slip over time). Also, if there's something to deal with tension on
>the string.. and what kind of string it might be?
>
>The second thing (and this one is a lot more complicated in my mind)
>is how the "button" style volume controller works. The best solution I
>came up with brainstorming last night would be to have the button a
>miniature version of a cry-baby wah-wah pedal, but with a spring so it
>returns to it's top position. The lever would be attached to a geared
>shaft which would ride against the gear of a potentiometer (just like
>in the wah wah pedal).
>
>Mike
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_______________________________________________________________________
Ken Stone   sasami at hotkey.net.au
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
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