In a message dated 2006/07/16, jonfr500@......... writes:

> Someone did write a program to use Mac computers with internal movement
> sensors as a seismometers.

Hi Jon,

       It is likely to be a strong motion sensor. I put an inexpensive design 
for a piezo disk semsor on John Lahr's website. 
http://jclahr.com/science/psn/index.html They cover down to below 0.5 sec and are more sensitive than 4.5 
Hz geophones. The disks themselves are maybe ~$1 each, but you also need a 
quiet FET input opamp. Maplins and Digikey stock suitable types.

       Regards.

       Chris Chapman
In a me=
ssage dated 2006/07/16, jonfr500@......... writes:



Someone did write a program to=20=
use Mac computers with internal movement

sensors as a seismometers.




Hi Jon,



       It is likely to be a strong motion sens=
or. I put an inexpensive design for a piezo disk semsor on John Lahr's websi=
te. http://jclahr.com/science/psn/index.html They cover down to below 0.5 se=
c and are more sensitive than 4.5 Hz geophones. The disks themselves are may=
be ~$1 each, but you also need a quiet FET input opamp. Maplins and Digikey=20=
stock suitable types.



       Regards.



       Chris Chapman