PSN-L Email List Message

Subject: Re: Opinion on seismometer
From: Dave Nelson davenn@...............
Date: Wed, 13 Jun 2007 20:59:50 +1000

   Hi Jon

    going by your pic ... It seems you have no mass (weight) at the end of=
the arm
and that is why the wire line is slack  also the terminating of that line=20
at the top
end is critical to overcome free swinging problems   follow Geffory's ideas=
using piano wire and turnbuckles and a good pivot point   etc,  as shown in=
the original Lehman design.

  a good mass would be ~ 5 - 10 kg of brass or lead
My commercial horizonal seismo had 10kg brass mass

  without any sort of reasonable mass on the arm   the seismo isnt going to
work   I assume you have something planned  ... altho you havent commented=
on what you are going to use.

Dave Nelson

At 10:19 PM 12/06/2007 +0000, you wrote:
>Hi Chris.
>The sensor is 95% done, I hopefully am going to finish it in about two
>weeks time or around that. The arm is 60 cm long. I am using a simple
>wire on the arm, from the top to bottom.
>I plan to use the magnet damping system as it is on that webpage you
>pointed to. I just can't set it up at the moment, I am going to get help
>in two weeks time to fix that issue and setup the sensor in a decent
>way. I am also going to fix few bugs that I currently have. But the arm
>goes straigt trugh the holder, it was a mistake that I did when it was
>setup up for me, my mistake. It is going to get that corrected, along
>with few other things.
>J=F3n Fr=EDmann
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