🚀 go-pugleaf

In article <586@aoa.UUCP>, carl@aoa.UUCP (Carl Witthoft) writes:
> >A friend of a brother of mine is an artist who is interested in two items:
> >1.  A battery that can be trusted after 100 years of storage,
> >2.  A clock of some sort to alarm after 100 years.
>
> any hunk of calibrated radioactive stuff with an attached geiger 
> counter.  When the count rate drops to a preset limit, fire the alarm.

	The problem, as I see it, is not so much finding a suitable power
source, but finding an electronic timing and control circuit which will
work for 100 years.  This is not a trivial task; it is not a trivial
assumption that say, a CMOS timing circuit will work for 100 years without
failure.
	There are various types of failure modes in solid-state circuits
which would manifest themselves over this period of time; such failure
modes include, but are not limited to: (1) undesireable migration and
diffusion effects; (2) corrosion effects; and (3) growth of micro-fine
metallic "whiskers".  Present reliability design and testing methods
for semiconductors do not cover the eventualities of a 100-year service
life.
	A pioneer in the development of components and circuits with
a long service life is Bell Laboratories.  Some of these interesting
problems have been discussed within the "Bell System Technical Journal".
A most interesting series of articles appeared between 1955 and 1957;
these articles dealt with the problem of designing undersea telephone
repeaters for the first Transatlantic Telephone Cable (i.e., the first
_voice_ cable, which was not installed until 1956).  These undersea
repeaters had a design life of something like 40 years, and the BSTJ
articles discussed such problems as growth of metallic whiskers on
various components.
	I would recommend these articles as interesting reading.

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
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