[sdiy] Substitute for pin matrixes?

[Tom Wiltshire]

On 23 Jan 2010, at 07:20, David G. Dixon wrote:

>> Push button switches -> microprocessor -> latches -> relays or high
>> voltage analog switches. If you did this right, you could even get
>> away with a single row and a single column of switches. An 8 x 8
>> matrix could be set up with 16 swtiches instead of 64. To make a
>> connection, you press the row switch and column switch that  
>> correspond
>> to the connection you want (sort of like playing "Battleship"), and
>> then an LED lights to show you the connection. Maybe some food for
>> thought for you microprocessor jockies.
>
> I think one could even do this fairly easily with logic chips...?

I agree. I don't even think it's much more expensive than a  
Ghielmetti matrix panel. Certainly in the same ball park. But it  
isn't "cheap".

You'd need a simple processor (a few dollars), some buttons, and a  
lot of LEDs, plus an analog matrix switch IC. Oh, and maybe some  
serial->parallel chips to drive the LEDs. The matrix switch and the  
buttons are the big costs.
If you wanted to go the whole hog, you could use lighted buttons and  
build the matrix out of those. Cheaper is to use the X-Y scheme that  
Tim suggested.

Either way, the ability to recall patches at the touch of a button  
has to be a massive benefit. Try that on a Synthi.

T.