Meridith Lamb
I appreciate the extensive infomation you provided regarding the hall sensor. 
 I have built a STM-8 basic seismo which is presently configured as a coil 
magnet unit (4 sec. period) since I am not presently skilled enough to tackle 
the electronics that Sean-Thomas's unit require.  I previously exchanged 
e-mail with Sean-Thomas regarding using the traditional SG electronics with 
the STM-8 of which he was encouraging for me to try.  However, it sounds like 
the hall effect approach would be almost a natural for this use and 
especially for someone with very limited electronics skills.  
Jim Allen
Cerritos, Calif.

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