[sdiy] Substitute for pin matrixes? Probability list update 2.

[Kyle Stephens]

Here's a solution with only two pots for an 8x8 matrix:

An X pot, and a Y pot, both wired as voltage dividers, each running into an 8-bit ADC. Each bit address intersects with an AND gate (quad AND, need 4 - and one input is for the X-axis, the other the Y-axis), the output of which turns on 1/8 of a 4051 (2x of those for 16 connections), with one switch 'pole' connected to a point on one axis, and the other pole to its respective spot on the other axis. If you need some visual indicator, a decoder and numerical LED array will get you there (more simply, if taking more space, two rows of LEDs tapped off of each address lines works too).

If you need more than 8x8 connections, you can just cascade an ADC with a binary weighted out and op amps, needing much, much less than 8 bits per 'bank' (vis-a-vis a VCDO), depending on how many connections we're talking here. (might want a coarse/fine pot setup at that point).

(8x8)^2 = 4096 possibilities (that's a Hans Zimmer-class synth!).
More reasonably, say (2x8)^2 = 256.

At its simplest as said, it's just two pots - if available real estate is an issue, this takes care of that.

You could even make the patching voltage controlled, putting CVs into the ADCs, ooh...just a thought.

The off-the-top-of-my-head-estimated bill for this would be, with surplus parts and let's say $0.50/most ICs...

2x pot = $3
2x ADC = $7
4x AND = $2
2x 4051 = $1
2x decoder = $2 (optional)
2x LED array = $6 (optional)

$15-23. Cheap?


_Kyle

--- On Sun, 1/24/10, karl dalen <dalenkarl at yahoo.se> wrote:

> From: karl dalen <dalenkarl at yahoo.se>
> Subject: Re: [sdiy] Substitute for pin matrixes? Probability list update 2.
> To: synth-diy at dropmix.xs4all.nl
> Date: Sunday, January 24, 2010, 9:20 AM
> Turning stones for something
> cheaper(dead cheap)then a Gillimetti matrix:
> 
> 1: Aligator clips on wire mesh as array.
> 2: Sub miniature SPDT arrays.
> 3: Toy railway/mechano sub sub bananas arrays.
> 4: 2.5mm tele arrays.
> 5: 3.5mm tele arrays.
> 6: 4mm bananas arrays.
> 7: Upside down IDC array resistor or wire as cross
> connects.
> 8. Turned IC holders arrays.
> 9:  Pin lists arrays.
> 10: Miniature push button arrays.
> 11: Veroboard layers as arrays, with bridge shorting
> between.
> 12: MT8816 and others, 4066, serial latches, MCU etc.
> 13: Latching Hall sensor arrays, controlling muxes.
> 14: Relay arrays, klicketi klack sound on its own.
> 15: Buchla paper solder punch card holders pluggable
> something.
> 16: A gigantic array of pots.
> 17: Fuse holder array.
> 18: Automatic fuse array.
> 19: Rims of plastic Lab plates arranged in arrays.
> 20: Standing sub miniature USB connectors, can carry 4
> signals each.
> 19: Replace the analog shit with digital DSP shit for plain
> convenience?
> 20: LDR Matrix with card with holes blocking a light
> source.
> 21: Spark gap and other high voltage switches, watch out
> for your safety.
> 
> At the moment im out of ideas so i just post a updated
> probability
> list as a reference for folks to know what has been
> discussed so far!
> Not saying you shouldn't evolve over it again, perhaps you
> find
> something this time you didn't find the first?
> 
> KD
> 
> 
>      
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