PSN-L Email List Message

Subject: Re: Magnetic Phono Cartridge as a Seismic Velocity sensor ?
From: Brett Nordgren brett3nt@.............
Date: Wed, 12 May 2010 14:26:44 -0400


Goeff,

An excellent reference to seismometer designs in general may be found at

http://www.reference.com/browse/Seismometer

 From that page:
" Early seismometers used optical levers or mechanical linkages to 
amplify the small motions involved, recording on soot-covered paper 
or photographic paper.
   Modern instruments use electronics. "

In general obtaining adequate amplification is not a problem.  A 
90-cent Operational amplifier can provide all the gain you could ever 
use.  The main problem will be obtaining a sufficiently stable, 
low-noise, motion sensing device.

Brett


At 11:31 AM 5/12/2010, you wrote:
>Back to the light thingy,
>Given A Mass and Spring:
>It Seems To Me You might get
>X1000 magnification of motion
>by putting a light source with a small radius
>fixed to a stationary location connected to the mass and then
>like 50 to 100 feet more away sensing
>the lights motion.
>It all has to do with the fact that as the radius increases
>so does the velocity at the perimeter.
>And if you can bounce the light beam between two mirrors
>It might travel 100 feet in a relatively small space.
>It will not matter that light is only 400 to 800 angstrums ??(not 
>sure of spelling)
>because one nano meter at the source becomes one micro meter
>at its destination, and, like light has no mass ??
>
>Have you ever seen such a mechanically amplified sensor before ?


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