PSN-L Email List Message

Subject: Re: Spring Damping.
From: "Geoffrey" gmvoeth@...........
Date: Tue, 24 Jul 2007 00:56:28 -0700

I understand that no matter what the setup
you want the whatever to achive a damping
where after relese the object attains an
amplitude on the backswing of about 0.1
of the relese height.
It would be nice to understand how this
translates to Q which is simply the inverse of damping.
I have found it best to use as little damping as possible
with a geophone that already has internal damping
related to construction. especially if you are
looking below the F0 point.
If you are only looking for first time of arrival you want
the greatest sensitivity possible.
I get the best pictures when my geophone is damped
the least so i do not understand why everyone
wants so much damping. But I was told by Mr.Willis Jacobs
of the USGS that they wanted a 10:1 damping ratio.
Release at 10 and on each half cycle it will be
only 10% the previous amplitude.

Does anyone know the proper formula to
translate swing amplitude to Q or its inverse
called damping ?

10:1 = _____Q ????


----- Original Message ----- 
From: "Paul Cianciolo" 
Sent: Monday, July 23, 2007 11:58
Subject: Spring Damping.

> Folks,
> I just finished up a  vertical  sensor with an AS-1 like suspension.
> After looking at the AS-1 pictures, and reading about it, I cannot see any
> information about the damping of the suspension spring.
> Does any one have one of these?  What am I missing because the spring being
> used here while allow in for almost 4 sec. period, once excited rings for a
> long time.
> It seems that a magnet mounted in the center of the spring, and an aluminum
> plate is very effective in reducing these.
> Any ideas?
> My spring is ferrous, and I would like to get a non ferrous replacement.
> PauLC

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