[sdiy] Building an expression pedal for MS20

[Michael E Caloroso]

Korg used to make the MS04 expression pedal, built in LFO and CV
control.  Neat accessory.

MC

On 2/25/15, rsdio at audiobanshee.com <rsdio at audiobanshee.com> wrote:
> Many synth foot pedals are already wired with the 1/4" stereo jack that
> Quincas is using. The voltage comes in on the Ring and Sleeve, is wired to
> the pot internally so that the wiper voltage comes out the Tip of the plug.
> (I may have Tip and Ring reversed). Basically, a pot is a 3-terminal passive
> device, and the 1/4" stereo jack offers all three terminals directly.
> There's nothing else in those pedals.
>
> The only drawback of these passive pedals is that they don't provide voltage
> unless you feed it to them. But that's actually a benefit, because it means
> they're compatible with 10 V CV or 5 V CV by just sending a different
> voltage.
>
> The box that Quincas built solves the only problem with the passive pedal by
> providing power.
>
> I wouldn't be surprised if some modular company already has a module that
> takes power from the bus and has a 1/4" jack for the expression pedal, maybe
> with the attenuator that Quincas has on his custom box for extra control. I
> looked at Synthwerks because they have very similar modules, but I didn't
> see anything that would work with a standard, passive synth expression
> pedal. Maybe this is an opportunity for a new product?
>
> Brian Willoughby
> Sound Consulting
>
>
> On Feb 25, 2015, at 6:31 AM, Quincas <quincas at gmail.com> wrote:
>> An expression pedal is just a potentiometer controled by foot. I use one
>> with my modular all the time. Basically I made a little box with a 9 v
>> battery inside and two jacks. One stereo jack sends 9v to the pedal and
>> receives the attenuated voltage back. That voltage goes through another
>> pot in the box for range control then out the second jack to the modular.
>> Normally I use it to control filter cutoff, lfo or delay speed, etc. fun
>> easy diy project, have fun!
>>
>>> On 25/02/2015, at 6:07, Jean Bender <lofideadbeat at gmail.com> wrote:
>>> Well, for a musical project, i need to control some parameters from
>>> the MS20 with an external processor, and that's would be really great
>>> if it could be controlled by foot.. In order to play with the cv
>>> inputs cutoff. It should really do the same as when you are manually
>>> turning a pot..
>>> A bit like the mod wheel, but for the foot..  An expression pedal like
>>> should be great, but i would have to build in a lfo ? Or a vco ?
>>> Would somebody have advices, ideas.. Maybe this kind of project already
>>> exist..
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