Hi all, I finally constructed a horizontal diamagnetic seismometer with eddy current damping. It uses a levitated magnet mass, with attached plastic spacers on each end. On one end is a attached Radio Shack "pill" neodymium magnet; which is centered over a Hall sensor for output. Its been fun messing with, but I wouldn't recommend this approach....other than pure experimental tinkering. Realistically, one could roughly classify it as a Shackleford/Gunderson type seismometer/pendulum, as the levitated mass simply hangs with reference to the overhead ferrite magnets and other forces. For the moment there is no magnetic shielding, nor any temperature maintenance circuitry, and it only is inclosed in my normal "vault". The Hall circuit is the same as used with other S/G horizontal seismometers, less the 10K output attenuation resister, on the same web page, and for the moment, it maybe capable of 30 second response. See: http://www.geocities.com/meredithlamb/index.html and go to the "A Diamagnetic seismometer experiment", (it can take afew minutes to load, and/or the "Diamagnetic comparison graphs to other sensors" boxes, which for the moment only contain acouple nearby quake records. The graphs are GIF images from Larry's Winquake program. The results mostly show more response to LQ or LR seismic disturbances. Naturally it shows the larger bus and motor vehicle magnetic influences. It doesn't seem to show the same short period responses as the other comparison seismometers...but on the other hand, some of the 5-10 second phases remain perplexing as too reason/source. Credits for this experiment go to, Robert Lamb, John Lahr, Dann Bartmann, Charles Patton and Martin Simon, for their information and material assistance efforts. Thanks guys! Thanks, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>