yup Chris

     jst some more typo's    :)

cheers
Dave

At 06:45 PM 25/03/2006 -0500, you wrote:

>In a message dated 25/03/2006, davenn@............... writes:
>   Bi-FET Op-Amps     ....  eg  the  OPA 027  and  similar
>series,  rather 741   etc type
>Hi Dave,
>     Google can't find an OPA027 ! and neither can I !!
>     OPA27 are very low noise, but they are not Bi-FET The later types are 
> OPA227 LT1007 etc
>     In general, FET opamps have a much higher voltage noise than ordinary 
> transistor types. I would not use one by choice in a geophone or a coil 
> sensor circuit. Some of the less expensive / older types suffer from step 
> noise - transient level or pulsed shifts.
>
>     When you connect up a geophone, you need to wire the metal case to 
> the earth / shield line.
>
>     Regards,
>
>     Chris Chapman
>
>
>No virus found in this incoming message.
>Checked by AVG Anti-Virus.
>Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 24/03/2006


yup Chris


    jst some more typo's    :)


cheers

Dave


At 06:45 PM 25/03/2006 -0500, you wrote:


In a
message dated 25/03/2006, davenn@............... writes:

  Bi-FET Op-Amps     ....  eg 
the  OPA 027  and  similar 
series,  rather 741   etc type
Hi Dave,

    Google can't find an OPA027 ! and neither can I
!!

    OPA27 are very low noise, but they are not Bi-FET The
later types are OPA227 LT1007 etc

    In general, FET opamps have a much higher voltage
noise than ordinary transistor types. I would not use one by choice in a
geophone or a coil sensor circuit. Some of the less expensive / older
types suffer from step noise - transient level or pulsed shifts. 

 

    When you connect up a geophone, you need to wire the
metal case to the earth / shield line.

 

    Regards,

 

    Chris Chapman




No virus found in this incoming message.

Checked by AVG Anti-Virus.

Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date:
24/03/2006





No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 24/03/2006