> > R1 R2 Potential Divider at all the sources and switch the low
voltage?
> >
>=20
> Great idea, but would prefer to have just the one PD to avoid having
to
> calibrate against the tolerances of other ones. Could use precision
> resistors I suppose, but am not yet sure about cost/benefit of that
> compared to finding some suitable switching method.

For some reason this has taken a while to reach me.

Are you just looking for a 'voltage present/absent' indicator, or to
measure actual voltage? If the latter then you will have to do some form
of factory calibration routine anyway, and it may as well store a fiddle
factor into EEPROM for each divider. This would be easily automated as
part of the test routine.
--=20
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--=20
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