PSN-L Email List Message
Subject: Re: Real time traces
From: Brett Nordgren brett3nt@.............
Date: Fri, 14 Aug 2009 15:10:28 -0400
The 2 instruments are two copies of almost exactly the same design. There
are a few minor evolutionary changes, but the only significant difference
is in the design of the pressure containers surrounding them. It is much
fun (for me anyway) to watch them draw out virtually identical traces of
the microseisms, right along with the Guralp.
One thing we have learned in working on this design is that the pivot
flexures have almost no effect. All my earlier efforts at making
zero-moment designs just aren't necessary. Any slight restoring moment
that the flexures create is completely cancelled when the period is
adjusted as Dave described, by tweaking the spring length. And the angle
that they flex through during normal operation is essentially zero because
of the feedback.
I just checked on the Garden Shed/Vault that I believe Dave had used:
Rubbermaid RHP3673 Approximately a 6' x 6' base.
In looking for the model number I ran across this somewhat amusing clip of
a couple assembling a similar shed.
At 11:51 AM 8/14/2009 -0600, you wrote:
>Hi Brett and Dave,
>I'am "assuming" the "2" instruments is really the one ~ same ~ vertical
>(?), with either mechanical changes and/or
>As usual (for me), the main spring (phosphor bronze) and the two pivot
>flexure assemblys (with presumably 6 total pieces) are of quite some
>curiosity. Of what material, size/s, thickness are you guys using? Some
>of the flexures shown almost look
>like cut thin flat spring steel from the photo.
>Take care, Meredith
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