I have been playing around with a dismantled SPZ geophone damping and find=
 if you short the leads to the coil and then drop the mass=20
the mass will descend slowly, I guess from meeting the generator current=
 being dissipated by the internal resistance.=20
=20
Questions arise from this.=20
=20
1. if there were no internal resistance (superconductor)   then when the=
 leads are shorted the mass would fall=20
  a bit then stay forever hovering ?=20
=20
    Correct
=20
2.the geophone is acting just like a rotating electrical generator=20
armature developing torque under electrical loads ?=20
=20
    Correct
=20
3. It seems to me that seismic noise rarely hits the resonant frequency an=
d=20
  you might do better to not increase the damping over what already=20
  is there in the mechanical and physical sense ?
=20
    No. The critical damping allows you to get an output voltage flat with=
 frequency above the resonant frequency.=20
=20
4. Does the rate at which the geophone mass drop under heavy damping repre=
sent some new fundamental Eigen frequency?
=20
    No. The resonance is determined by the mass of the armature and the sp=
ring constant. =20
=20
5. Can anyone provide me with high school math models which represent the=
 mechanical and electrical behaviors of the geophone?=20
  High school math being trig and algebra minus the calculus?
=20
    The theory is freely available on the Internet.
=20
an Eigen freq not contained in EQ signals then do no damping at all?=20
This [little damping] should work for weak EQ signals and not close strong=
 ones ?=20

=20
      An undamped geophone has a single frequency peaked response - defini=
tely NOT what you want! =20

     Regards,


     Chris Chapman


























I have been playin=
g around with a dismantled SPZ geopho=
ne damping and find if you short the lea=
ds to the coil and then drop the mass 

the mass will descend slowly, I guess from meeting the generator curr=
ent being dissipated by the&nb=
sp;internal resistance. 

 

Questions arise from this. 

 

1. if there were no internal resistance (superconductor)   then=
 when the leads are shorted the mass would fall 

  a bit then stay forever hovering ? 

 

    Correct


 


2.the geophone is=
 acting just like a rotating electrical generator&nb=
sp;

armature developing torque under electrical loads ?&=
nbsp;

 

    Correct


 


3. It seems to me=
 that seismic noise rarely hits the resonant frequen=
cy and 

  you might do better to not increase the dampi=
ng over what already 

  is there in the mechanical and physical sense=
 ?


 


&nb=
sp;   No. The critical damping allows you to get an output=
 voltage flat with frequency above the resonant frequency. 
 

4. Does the rate at which the geophone mass drop under heavy damping represent some new fundamental=
 Eigen frequency?



 

    No. The resonance is determined by=
 the mass of the armature and the spring constant.  


 



5. Can anyone provide me with high school math mo=
dels which represent the mechanical and =
electrical behaviors of the geophone<=
/FONT>? 

  High school math being trig and algebra minus the calculus?



 



&nb=
sp;   The theory is freely available on the Internet.


 


an<=
/FONT> Eigen freq not contained in EQ signals then=
 do no damping at all? 

This [little damping] should work for weak EQ signals and not close strong ones=
 ? 



 


      An undamped geophone=
 has a single frequency peaked response - definitely NOT what you want!&nb=
sp; 



     Regards,



 


     Chris Chapman