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Subject: "EPICS" seismo suggestion
From: meredithlamb meredithlamb@.............
Date: Fri, 13 Sep 2002 16:02:13 -0600

Hi all,

I would suggest "S-G's" (Shackelford-Gunderson) type seismo's
as being perhaps the easiest to build.  They simply are pendulums
that hang downward, and have used a variety of sensors that I've
noted.   These are horizontal sensitive instruments.  About the
most important part mechanically seems to have been just the
0.001" thick X ~1.5" length brass hinge/s I used; it seemed to
need the flexibility there for longer period (electronic capacitive
storage) response to distant quake phases with periods ranging up
to > ~30 seconds.

I've little electronics experience per'se, but the Hall sensor type
designed by my (deceased) brother Robert back in ~ 1997, seems to be
another design that any interested partys might wish to review....
if for nothing more than the basic simpicity of the mechanical doesn't have to exotic....just mechanically stout.
Robert Lamb was a electronics engineer for H-P and Texas Nuclear.

Perhaps the biggest negative is the Hall sensors generate more
"noise" than is desired.  Being as the Hall S-G is a stable gravity
related instrument, I've seen that after construction and a
reasonable period of mechanical settling in time, that its been
much more dependable than any of my Sprengnethers and
their "hanging gate" pendulums for temperature and even
moreso for ground water related tilt effects tolerance.  I do
suggest that any replicators have a fair degree of electronics
knowledge...even though the circuit is not excessively
complicated.  Its likely the majority cost expense will be with
the Hall circuit itself.  The circuit/instrument was designed
to be a simple (comparisons) general instrument, with none of
the extreme complexities that alot of manufacturers seismo's
and circuits claim to attain.

Take care, Meredith Lamb


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