In a message dated 2006/11/19, gmvoeth@........... writes:

> Does anyone understand how this circuit will affect the geophone ?
> 
> If so can you show me in laymans terms what is happening ?
> 
> http://gmvoeth.home.mchsi.com/geoamp01.GIF

Hi Geoff,

       I haven't worked out the balance equation, but this is a -ve input 
impedance circuit, presumably to very heavily damp the geophone. This should / 
could cause the output to have a 1/f characteristic, rather than the normal 
dogleg, flat down to the resonance and 1/f^2 below this. 
       This type of circuit is used to 'broad band' a geophone response. 
Where did it come from?

       Regards,

       Chris Chapman
In a me=
ssage dated 2006/11/19, gmvoeth@........... writes:



Does anyone understand how this=
 circuit will affect the geophone ?



If so can you show me in laymans terms what is happening ?



http://gmvoeth.home.mchsi.com/geoamp01.GIF




Hi Geoff,



       I haven't worked out the balance equati=
on, but this is a -ve input impedance circuit, presumably to very heavily da=
mp the geophone. This should / could cause the output to have a 1/f characte=
ristic, rather than the normal dogleg, flat down to the resonance and 1/f^2=20=
below this. 

       This type of circuit is used to 'broad=20=
band' a geophone response. Where did it come from?



       Regards,



       Chris Chapman