In a message dated 04/07/06, gpayton880@....... writes:

> I just found this information on the Internet:
>     "Cooling a magnet improves the overall ordering (of domains) and makes 
> it magnetization stronger."
>  
> If a magnet's strength increases, even minutely, it would affect the induced 
> current in the coil proportionally. This could cause the slight increase in 
> trace's signal strength.
>  
> My magnet is laying on the concrete floor absorbing any temperature changes. 
>  I am going to try to laying my magnets on a piece of thin Styrofoam, 
> insulating it from the floor, and see how it responds tonight.

Hi Jerry,

       You didn't say what material your magnet was made from? In order of 
temperature stability, Alnico and similar are best, NdFeB of several 
compositions, Sm/Co, and Ferrite is the worst. You also have differing thermal 
expansions, which effect the pole gap.
       Alnico is about 1x10^-4 / C Deg. With the considerable mass and heat 
capacity of the magnet, you are unlikely to see any direct thermally induced 
signals in your coil at the periods you observe. The rate of temperature / field 
change will be too low.
      One of the objectives in amateur seismometry is to provide an 
environment with the greatest practicable stability and the lowest noise. 

       Regards,

       Chris Chapman
In a message=20=
dated 04/07/06, gpayton880@....... writes:



I just found this informati=
on on the Internet:

    "Cooling a magnet improves the overall ordering (of d=
omains) and makes it magnetization stronger."

=20

If a magnet's strength increases, even minutely, it would affect the ind=
uced current in the coil proportionally. This could cause the slight increas=
e in trace's signal strength.

=20

My magnet is laying on the concrete floor absorbing any temperature chan=
ges.  I am going to try to laying my magnets on a piece of thin Styrofo=
am, insulating it from the floor, and see how it responds tonight.



Hi Jerry,



       You didn't say what material your m=
agnet was made from? In order of temperature stability, Alnico and similar a=
re best, NdFeB of several compositions, Sm/Co, and Ferrite is the worst. You=
 also have differing thermal expansions, which effect the pole gap.

       Alnico is about 1x10^-4 / C Deg. Wi=
th the considerable mass and heat capacity of the magnet, you are unlikely t=
o see any direct thermally induced signals in your coil at the periods you o=
bserve. The rate of temperature / field change will be too low.

      One of the objectives in amateur seismome=
try is to provide an environment with the greatest practicable stability and=
 the lowest noise.=20



       Regards,



       Chris Chapman