AW: [sdiy] Goofy matrix switch idea

[Ullrich Peter]

Hallo!

>I have always wanted to use a CD22100 4 x 4 crosspoint switch in a
synth.
>They contain 16 switches in a 4 x 4 matrix. Obsolete now, but you can
find
>them in the surplus pipeline. They were $0.95 when still in production
and
>handle +/- 5 volt signals.
>
>The problem is they are programmed with a pulse train to set the
switches on
>or off. It normally needs a 16 bit shift register or microprocessor to
>control them.
>
>Anyway, I realized the patterns from a CD4089 rate multiplier chip
MAYBE
>could be used to program the switches. Mostly turn them all on with
only two
>on at the smallest setting. Or invert the logic and turn them mostly
off, or
>gate the pulse train???
>
>Very cheap and might be a patch matrix for a circuit bent thingie or
>electronium.

Not so cheap but more flexible and with a parallel programming interface
are
the matrix circuits from Mitel. I use the MT8816 (16x8) for a
MIDI-Interface for polyphonic synths
(Poly61 from Korg, Casio SK1) and they work fine. They are also suitable
for
audio signals and also video signals. Made an audio matrix with them.

But if you want to realize a mixing matrix (summing signals) you have to
do some tricks
as there are no summing resistors included.

Ciao
Peter

        \|/
       (o o)
--oOOO--(_)--OOOo------------------------------------------------------
                   Ing. Peter Ullrich         mailto:ullrich at kapsch.net
                   Homepage: www.ullrich.at.tt , http://come.to/ullrich
                   http://www.geocities.com/SiliconValley/Heights/3586/
   .oooO           Hardware & Software Developer /  Electronic Musician
   (   )   Oooo.   KAPSCH AG / ECCN Control Systems    Vienna / Austria
----\ (----(   )-------------------------------------------------------
     \_)    ) /
           (_/