Hi, Roman

    I just received and "official" answer from a membrane keyboard
manufacturer and he says that the resistance varies with many factors,
flexing of the flat cable, humidity, number of keypresses, temperature and
some other ones that I cannot remember ! The resistance can go up to 500
ohms without the keyboard being considered bad ! The silver connections
develops "micro cracks" and the resistance goes up.

    I think you cannot count on the 300 ohms tolerance of your design
reliably with membrane and carbon keyboards. It is a shame because it would
be nice to have a way to connect more keys. The method should still be valid
for the small "dome" switches that are pretty cheap.

Best regards,
Alexandre Guimaraes

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