From: Ted Channel 
To: psnlist@..............
Subject: Amplifier gains


I told him I did not know what gain we should target, but some of the sche=
matics indicated a gain of 2000.   He suggested  including a selector knob=
, with several gain choices.

Hi Ted,

    Larry's older board is at www.jclahr.com/science/psn/cochrane/index.ht=
ml

    Larry's current board has gains from 145 to 6000, set by a x10 variabl=
e pot and plug shorting connectors - they are easy to set and very reliabl=
e.=20
=20
If we were to try is approach, what would be some of the typical values fo=
r gain?    500, 1000, 1500, 2000?

    Depends on the coil + magnet system. I use gains down to x100 on my el=
ectronics, with 2" x 1" x 1/8" thick NdFeB magnets and a 2,500 turn coil.=
 x ~1" square.

We have a sensor with a strong coil, strong magnets, and are using Chris's=
 magnet assembly on a 20 second Lehman.
=20
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.
=20
    Check the gain shorting connectors and measure the resistence used on=
 the pot - with the power OFF.

    Regards,

    Chris Chapman










From: Ted Channel <tchannel@............>

To: psnlist@..............

Subject: Amplifier gains







I told him I did not know what gain we sh=
ould target, but some of the schematics indicated a gain of 2000. &nb=
sp; He suggested  including a selector knob, with several gain choice=
s.


 


Hi Ted,


 


    Larry's older board is at www.jclahr.com/science/psn/cochr=
ane/index.html


 


    Larry's current board has gains from 145 to 6000,=
 set by a x10 variable pot and plug shorting connectors - they are ea=
sy to set and very reliable. 


 


If we were to try is approach, what would=
 be some of the typical values for gain?    500, 1000, 1500=
, 2000?


 


    Depends on the coil + magnet system. I use gains=
 down to x100 on my electronics, with 2" x 1" x 1/8" thick NdFeB magnets=
 and a 2,500 turn coil. x ~1" square.


 


We have a sensor with a strong coil, stro=
ng magnets, and are using Chris's magnet assembly on a 20 second Lehm=
an.


 


On Larry's board, which I love, works per=
fectly, 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 perfe=
ct for my sensors.


 


    Check the gain shorting connectors and measure the=
 resistence used on the pot - with the power OFF.


 


    Regards,


 


    Chris Chapman