A note about gain: When I first started I used adjustable pots but I
found that by adding a couple of header pins I could wire wrap the
resister to set the amount of gain I needed and saved a few bucks. Once
it its set I don't change it that often. The other thing is that as in
my case, the insturments are outside in a box and the PC is in the
gurage, so I just build the amp portion of Pete's PSN design and then
mount it out with the siesmograph. The filters are mounted in a second
box near the PC that I externally connect to Larry's data collection
board. 
Regards, Steve Hammond PSN San Jose, Aptos CA.

-----Original Message-----
From: psnlist-request@..............
[mailto:psnlist-request@............... On Behalf Of Ted Channel
Sent: Friday, December 17, 2010 4:50 AM
To: psnlist@..............
Subject: Amplifier gains


I was telling a friend, I would like to try to build my own
amplifier/filter board.   He is knowledgeable in electronic, and I am
not.   So he said he would help.   His first question was about gain.
 
I told him I did not know what gain we should target, but some of the
schematics indicated a gain of 2000.   He suggested  including a
selector knob, with several gain choices.
 
 
If we were to try is approach, what would be some of the typical values
for gain?    500, 1000, 1500, 2000?
I know it depends on other factors, but I am trying to narrow it down.
We have a sensor with a strong coil, strong magnets, and are using
Chris's magnet assembly on a 20 second Lehman.
 
On Larry's board, which I love, works perfectly, the gain is selectable
from 200 to 9500?............I use it as it is shipped, so I don't know
what the gain is........but it is perfect for my sensors.
 
Somewhere I have seen an amplifier with a selector knob, for gain, but I
can't find it.
 
Thanks,
Ted










A note=20
about gain: When I first started I used adjustable pots but I found that =
by=20
adding a couple of header pins I could wire wrap the resister to set the =
amount=20
of gain I needed and saved a few bucks. Once it its set I don't =
change it=20
that often. The other thing is that as in my case, the insturments are =
outside=20
in a box and the PC is in the gurage, so I just build the amp =
portion of=20
Pete's PSN design and then mount it out with the siesmograph. The =
filters are=20
mounted in a second box near the PC that I externally connect =
to=20
Larry's data collection board. 
Regards, Steve Hammond PSN San Jose, Aptos =
CA.

  

  
-----Original Message-----
From:=20
  psnlist-request@.............. [mailto:psnlist-request@............... =
On=20
  Behalf Of Ted Channel
Sent: Friday, December 17, 2010 =
4:50=20
  AM
To: psnlist@..............
Subject: Amplifier=20
  gains


  
I was telling a friend, I would like =
to try to=20
  build my own amplifier/filter board.   He is knowledgeable =
in=20
  electronic, and I am not.   So he said he would =
help.  =20
  His first question was about gain.
  
 
  
I told him I did not know what gain =
we should=20
  target, but some of the schematics indicated a gain of =
2000.   He=20
  suggested  including a selector knob, with several gain=20
  choices.
  
 
  
 
  
If we were to try is approach, what =
would be some=20
  of the typical values for gain?    500, 1000, 1500,=20
  2000?
  
I know it depends on other factors, =
but I am=20
  trying to narrow it down.   We have a sensor with a strong =
coil,=20
  strong magnets, and are using Chris's magnet assembly on a 20 =
second=20
  Lehman.
  
 
  
On Larry's board, which I love, works =
perfectly,=20
  the gain is selectable  from 200 to 9500?............I use it as =
it is=20
  shipped, so I don't know what the gain is........but it is perfect for =
my=20
  sensors.
  
 
  
Somewhere I have seen an amplifier =
with a=20
  selector knob, for gain, but I can't find it.
  
 
  
Thanks,
  
Ted