Hi Chris,  Is this the type of Hall Effect Magnetic field detector chip  =
http://www.allegromicro.com/en/Products/Design/an/an27701.pdf

I see one chip can determined direction. X and Y?      If this is so, is =
there a way to apply that directional information to trip a relay or =
otherwise light a series of LED's
They look inexpensive, $2, so if not one, we could use several, (8) to =
form a compass.

Thanks, Ted
  ----- Original Message -----=20
  From: ChrisAtUpw@..........
  To: psn-l@.................
  Sent: Monday, March 17, 2008 4:37 PM
  Subject: Re: Scientific American 1884 Part 2


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


    But how would one record the pendulum direction of movement?=20


  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,
        =20







Hi Chris,  Is this the type of =
Hall Effect=20
Magnetic field detector chip  ht=
tp://www.allegromicro.com/en/Products/Design/an/an27701.pdf
 
I see one chip can determined =
direction. X and=20
Y?      If this is so, is there a way to apply =
that=20
directional information to trip a relay or otherwise light a series of=20
LED's
They look inexpensive, $2, so if not =
one, we could=20
use several, (8) to form a compass.
 
Thanks, Ted

  
----- Original Message ----- 
  From:=20
  ChrisAtUpw@....... 
  
To: psn-l@.............. 
  
Sent: Monday, March 17, 2008 =
4:37=20
PM
  
Subject: Re: Scientific =
American 1884=20
  Part 2
  

In a=20
  message dated 2008/03/17, tchannel1@............=20
writes:


  But how would one record the pendulum direction of =
movement?=20
    

Hi=20
  Ted,

       If you want tthe =
system to=20
  work for small quakes, use either a vertical magnet and two pairs of =
Hall=20
  Effect Magnetic field detector chips or use a disk on the end of the =
penduum,=20
  a lamp and four photocells.  Either of these could give you the X =
and Y=20
  sensitivities.
       Or make it to =
the=20
  design and accept that it is not a very sensitive device. Maybe put a =
flat on=20
  the top of the pendulum and set a ball bearing on the flat? This might =
give=20
  appreciable sensitivity?

      =20
  Regards,
      =20
  
       Chris Chapman=20