In a message dated 2008/03/17, tchannel1@............ writes:

> But how would one record the pendulum direction of movement? 

Hi Ted,

       If you want tthe system to work for small quakes, use either a 
vertical magnet and two pairs of Hall Effect Magnetic field detector chips or use a 
disk on the end of the penduum, a lamp and four photocells.  Either of these 
could give you the X and Y sensitivities.
       Or make it to the design and accept that it is not a very sensitive 
device. Maybe put a flat on the top of the pendulum and set a ball bearing on 
the flat? This might give appreciable sensitivity?

       Regards,
       
       Chris Chapman   
In a me=
ssage dated 2008/03/17, tchannel1@............ writes:



But how would one record the pe=
ndulum direction of movement? 




Hi Ted,



       If you want tthe system to work for sma=
ll quakes, use either a vertical magnet and two pairs of Hall Effect Magneti=
c field detector chips or use a disk on the end of the penduum, a lamp and f=
our photocells.  Either of these could give you the X and Y sensitiviti=
es.

       Or make it to the design and accept tha=
t it is not a very sensitive device. Maybe put a flat on the top of the pend=
ulum and set a ball bearing on the flat? This might give appreciable sensiti=
vity?



       Regards,

       

       Chris Chapman