> I have seen some devices that are built as home projects that have a nice
> panel on them that have a membrane type switch panel.  I'm curious if
anyone
> knows how to do this?

> I'm thinking of tactile switches with a panel label
> over them

That's one method (and a superior one). A common alternative is to have a
formal "membrane keyboard". These essentially consist of three layers of
plastic (usually Mylar/Polyester). The top and bottom layers have metallised
traces on them to form thre switch contacts and the middle layer has holes
allowing the two outer layers to be pressed together by finger (etc)
pressure. Somewhat superior results are achieved by embedding tactile snap
domes between the layers to give the keyboard some "feel".

A membrane (aka sheet of plastic) over a sheet of solid plastic eg 3mm+
polycarbonate or whatever with holes therein and tact switches mounted "just
right" behind it produces a far far better result than the above. "Real"
people mount the tact switches on a spearate panel which cam be adjusted for
position (depth behind the fron panel) so that the tact switches are
positioned "just right". One arrangement I know of uses o rings around the
screws between the front panel and tzct switch panel - the o rings are
compressed as the screws are tightened, allowing the gap to be adjusted.
This is amechanically annoying solution but far better than simple membrane
keyboards.

> but don't know how to mount everything or how far from the panel
> should they be?

The distance that works properly for the chosen switch :-) - hence the above
method.



        Russell McMahon

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