In a message dated 01/12/2007, psn@............ writes:

I am  using now a Burr Brown PGA204 instrumentation amp  for my tests.  Later
I want to try a
LT1028/1128. Does anyone know a better amp for a  400 Ohms coil?



Hi Andreas,
 
    The PGA 204 is relatively noisy
 
    The LT1028 is a bit better than the LT1007CN8, but  more expensive. You 
need to design the -ve input circuit with maybe 200 Ohms max  to ground and the 
geophone onto the +ve input.
 
    You can get lower noise if you use a differential  input pair of low 
noise transistors onto a LM301 opamp or similar.
 
    Regards,
 
    Chris Chapman 



   






In a message dated 01/12/2007, psn@............ writes:
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>I am=20
  using now a Burr Brown PGA204 instrumentation amp  for my tests.=20
  Later
I want to try a
LT1028/1128. Does anyone know a better amp for=
 a=20
  400 Ohms coil?


Hi Andreas,
 
    The PGA 204 is relatively noisy
 
    The LT1028 is a bit better than the LT1007CN8,=20=
but=20
more expensive. You need to design the -ve input circuit with maybe 200 Ohms=
 max=20
to ground and the geophone onto the +ve input.
 
    You can get lower noise if you use a differenti=
al=20
input pair of low noise transistors onto a LM301 opamp or similar.
 
    Regards,
 
    Chris Chapman