jrball wrote:I'm Interested if there is any difference between reeds and optos.
In my experience, reed switches have several disadvantages: they 'tick' audibly when mounted to a hard surface, they can have very considerable hysteresis, and they are not easy to set up consistently. This may not matter so long as they do switch on and off at some reasonably well defined points in the key travel, but it annoyed me too much and after one keyboard convertion, as an experiment, I changed to opto-interrupters which are silent, easy to set up quite exactly, and have rather little hysteresis (mostly determined by the Von and Voff levels of the microcontroller, or whatever, that is sensing their state).
I have also experimented with hall-effect sensors but decided that they offered no particular advantages and one or two disadvantages.
Nick
ps, I'm not really sure that this is the most appropriate part of the forum for this sort of discussion.