Hi Dave,  Do you have a picture of your commercial horizontal seismo, or wed 
site?
Thanks, Ted


----- Original Message ----- 
From: "Dave Nelson" 
To: 
Sent: Wednesday, June 13, 2007 4:59 AM
Subject: Re: Opinion on seismometer


   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
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.

cheers
Dave Nelson
Sydney



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.
>
>Regards.
>--
>Jón Frímann
>http://www.jonfr.com
>http://www.simnet.is/jonfr500/earthquake/
>
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