[sdiy] Substitute for pin matrixes?

[Tony Clark]

On Sun, Jan 24, 2010 at 7:29 PM, nicolas <nicolas3141 at yahoo.com.au> wrote:
> Many of the proposals seem oriented towards emulating the compactness of the original pin matrices, but this can be a disadvantage if it is going to be used as a performance oriented playing surface rather than a sound design patch panel.  My idea, which I plan to build, but haven't yet, is for a slightly larger more playable thing a bit like a steampunk monome.
>
> Imagine this:  (The suggested dimensions are for an array at 20mm centres, but when I actually get around to trying this I think I will be scaling it up slightly to a 30mm spacing to make it more playable.)  Three sandwiched layers, at the bottom a PCB with very wide heavy duty tinned tracks for the columns - 15mm wide tracks with 5mm gaps between.  Then an insulating layer 4mm thick with an array of holes - 14mm holes spaced at 20mm centres.  Then rows made of brass strap, 16mm wide, 2mm thick, with 12mm holes at 20mm centres.  All carefully glued together and mounted on a tilt like the tops of many commercial desktop synths.  For pins I would use lead balls 10-11mm diameter.  Steel ball bearings would look better, but I am not sure that the contact would be as reliable as lead.

Maybe I'm not quite envisioning this correctly, but you can simplify
this down to just a single layer of PCB with a hole (smaller than the
size of the ball)  that has two plated half-rings around the edge.
When you drop your ball in, it will connect the one half to the other.

Cheers,

Tony

-- 

Tony Clark
Great Lakes Modular
www.greatlakesmodular.com
Design, Engineering, and Manufacturing Services