This is an old post, preserved for reference.
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These are the same size and function as the ZX81 versions, but are slightly thinner and are plain black rather than having the ZX81 keyboard printed on them. They are produced for me by RWAP (who also suggested the idea), so are the same top quality as their ZX81 replacement membranes.
When removed, that shows the matrix off nicely. The ZX81 version has a white background, so you don't see the matrix as clearly. Not that it matters as you normally attach that straight to a ZX81.
However, this looks great on the underside of a Minstrel clone on a clear perspex sheet.
If you wanted to, I suppose you could use one of these to create a stealth ZX81 or TS1000.
However, in practice, you probably want to apply a stick on keyboard overlay.
And then you are back to a TS1000 with a working keyboard (complete with the TS1000 labelling which differs from the ZX81 on a couple of keys).
I have been using these on the Minstrel ZX80 clones I build in white ZX81 cases. I usually start with pretty beat up ZX81's.
Sanding the top gets rid of the scratches and dings and the raised ZX81 logo.
With these blank membranes, I have been fitting them before painting, to give a cleaner line around the stick on overlays.
Available with keywords for either the original 4K BASIC
Or the ZX81 style 8K BASIC.
Finally, back to the open frame version of the Minstrel clone.
As requested by a previous buyer, this can be supplied with both overlays and both versions of BASIC so they can decided which one to use.
4K if you want to be authentic to the original ZX80, 8K if you want to use it for more things.
I have sold out of the blank membranes, so will be supplying standard ZX81 membranes. They look the same once the overlay is applied anyway.