AW: Matrix board! (a CMOS one)

[Bissell, Harry]

It  might be possible to get a mixing effect by driving the matrix with
transconductance amps (3080?) the outputs of these can be tied together and
will source and sink current to each other. Another possibility might be to
use a "multi level" matrix, something like one matrix feeding resistors
feeding a second matrix... but if it was me, i would't bother. I'd sooner
build a matrix using 1/4 " jacks as someone suggested earlier. Harry Bissell

> -----Original Message-----
> From:	Haible Juergen [SMTP:Juergen.Haible at nbgm.siemens.de]
> Sent:	Friday, February 26, 1999 8:11 AM
> To:	DIY; edusilva at bahianet.com.br
> Subject:	AW: AW: Matrix board! (a CMOS one)
> 
> 	>According to the statement "during power up, all switches are
> automatically
> 	<reset", I assume that it can turn on more than one switch at a
> time. 
> 
> That alone would not help at all. If it's just switches, it would more or
> less short 
> whole columns and rows together.
> Example:
> Asuming A, B, C, .... are the inputs and #1, #2, #3, ... are the outputs.
> You want A to modulate #2, and
> both A and C to modulate #1.
> So you'd set the connections A#2, A#1 and C#1.
> If it's all just switches, the whole A and C input rows would be wired
> together
> (over their connection with #1). Therefore you would also have an
> unintentional
> modulation path from C to #2 (amongst other side effects).
> What you need is a resistive connection for each matrix element, with the
> input
> rows being buffered and the output columns being true summing nodes.
> It would not be completely out of reach to integrate such a scheme
> (transmission
> gates are not perfect shorts), but I have my doubts that this implemented
> in
> these arrays.
> 
> JH.