[sdiy] Analog crossbars and backplanes

[Ullrich Peter]

Hi!

In the Poly61 the matrix is in parallel with the keyboard atrix -decoupled via diodes.
OK, this is a bit of an overkill - simulating the keypress pattern is an easier method from the part count, but my version is more universal as it could be used with nearly every synth that has a keyboard matrix - independing of the scanning timing as the matrix circuits emulate keypresses... but as I said an overkill... The matrix circuits are not cheap...

In the patchbay I switched the digital MIDI and analog SMPTE audio signals (modem signals) through this matrix circuits. Only the music audio signal have not been routed through the matrix chips.

I also used a similar circuit - the MT8812 for the casio SK-1 midi interface I made about 15 or maybe years ago. 

Ciao
Peter

______________________________
Von: cheater00 . [cheater00 at gmail.com]
Gesendet: Sonntag, 10. November 2013 23:53
An: Ullrich Peter
Cc: Tom Wiltshire; synth-diy
Betreff: Re: [sdiy] Analog crossbars and backplanes

Hi Peter,
thanks for your email.

On Sun, Nov 10, 2013 at 11:48 PM, Ullrich Peter
<Peter.Ullrich at kapsch.net> wrote:
> Hi!
>
> I used the MT8816 for some projects (one of these was a patchbay for SMPTE and MIDI- and audio signals, the music audio signals have been switched via little relays for best quality but MIDI and SMPTE with the MT8816) . I also used it for a Korg Poly61 MIDI-Interface - in parallel with the keyboard.
>
> Datasheet: http://www.futurlec.com/Datasheet/Zarlink/MT8816AE.pdf
> It a 8x16 matrix
>
> Ciao
> Peter
>
> http://www.ullrich.at.tt

In your Korg Poly61 project, what signals were connected through the
MT8816? Did you use it to hook up to the bus going from the CPU to the
diode matrix in the keyboard? I understand in the patchbay only
digital signals were connected through this chip.

BTW, it's worth noting for anyone reading this that "8x16" means 8
horizontal x 16 vertical crossbars, and any of them can be used as
input or output.

Cheers,
D.



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