> So looking for a non powered visual indicator..ie...something that
> changes color, that would be tripped by the micro that a tech would be
> able to look at and say...failed board due to....X
>=20
> So when the board is running this "thing" can be controlled and then
> its forever changed in state, even with the power off.
>=20
>=20
> Can't have smoke...so making a resistor crispy isnt allowed.
>=20
> Any thoughts?

Around 20 years ago QANTEL used a flappable indicator that was fluorescent =
yellow one side and black on the other. It had a coil that required a pulse=
 to set it, and a reverse polarity pulse to 'unset' it. They used it on a m=
emory module to indicate when a parity error occurred, so the engineer coul=
d see which module to replace.

The module they used was made by Ferranti IIRC. They were originally design=
ed for use in large annunciation displays at public transport stations or s=
ports fields, with each module being one dot of a dot matrix display.

See http://en.wikipedia.org/wiki/Flip-disc_display for further info, and it=
 looks like there is a link to the manufacturer.


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