[sdiy] Keyboard Controller - needs poly help

[harrybissell]

Once you pass the two note solution, it would be more effective to go
to a scanning, or digital priority keyboard.  There are many ways to do
it...

One way would be to have an output from a binary counter that is decoded

to each key... as the counter counts up...anytime a key if found pressed
it
would latch that address into a D/A converter... and proceed to the next
key.

When four keys are scanned you start from the beginning again.

There are schematics on the web for Oberheim's version of a scanning
keyboard.
(at synthfool, iirc)

If you have the chops, a simple PIC would do it.  Another solution would
be to use
a MIDI keyboard encoder and a MIDI/CV converter.  Roman Sowa (hi ;^)  of
this list
makes some very nice, small encoders with a PIC micro.  For the MIDI/CV
part you
have a choice of MANY suppliers.

H^) harry

Peng wrote:

>  I have a few organ keyboards I saved from the garbage that I want to
> convert to modular controller (obviously). They have four independant
> switches to each key. I'll want to use the schematics from Ray
> Wilson's site :
> http://www.musicfromouterspace.com/analogsynth/keybrdcontroller.html I'm
> thinking if I do the switch bus connections as shown I get low note
> priority. If I reverse the connections for the second switch bus I'll
> get high note priority. Each bus will have its own CV,gate,trigger
> jacks so if I hook one bus to VCO1 and the other to VCO2 I should get
> this: press one key, both VCOs play same pitch. Hold the first and
> press another key and VCO1 and 2 will see different voltages. That all
> seems pretty straightforward but I still have two more switch buses to
> deal with. I want these to have their own CV,gate,trigger jacks just
> like the other two. they'll have seperate oscillators, too, so there's
> VCO1, 2, 3, and 4. Now, press four keys and you get four different
> pitches. I know the two keys I'm holding in the middle will need to
> work off the others (highest and lowest held notes) or else they will
> play the same notes as the high and low part. Can anyone give me some
> clues as to how this could be done ? I'm a novice so any keywords,
> advi! ce, whatever will be greatly appreciated. Thanks,P.
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