In a message dated 09/06/2006, gpayton880@....... writes:

Does  anyone have any GOOD photos of a completed Lehmann  Sensor?


    I have a scale drawing if that would be any  use?
 
    I use two 1/4" thick bright mild steel plates,  2" wide by 3.5" long. 
They are held apart by 3 or 4 zinc plated 3" mild steel  set screws with three 
nuts each. On the centre inside of both plates I fit two  1" square by 1/8" 
thick NdFeB square magnets to give an arrangement ->
 
Bolt                            Bolt 
XXXXXXXXXXXXXXXXXXXXXXX Backing plate
           NNNNSSSS
            <--  Coil -->
           SSSSNNNN
XXXXXXXXXXXXXXXXXXXXXXX Backing plate
Bolt                            Bolt
 
    I find that this works very well and it is easy to  adjust. The coil that 
I use came as a spare for a 220V water valve on a washing  machine and it is 
about 3/8" thick by slightly over 1" OD, about 5,000  turns. 
    I use the same layout but with 1"x1/2"x1/4" NdFeB  magnets for the 1/16" 
Cu damping plate.
    Any internal field inbalance is shorted through the  bolts and the 
external field is near zero.
 
    Hope that this helps.
 
    Regards,
 
    Chris Chapman






In a message dated 09/06/2006, gpayton880@....... writes:
<=
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  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
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  anyone have any GOOD photos of a completed Lehmann=20
Sensor?

    I have a scale drawing if that would be any=20
use?
 
    I use two 1/4" thick bright mild steel pla=
tes,=20
2" wide by 3.5" long. They are held apart by 3 or 4 zinc plated 3" mild stee=
l=20
set screws with three nuts each. On the centre inside of both plates I fit t=
wo=20
1" square by 1/8" thick NdFeB square magnets to give an arrangement ->
 
Bolt           &=
nbsp;            =
;    Bolt 
XXXXXXXXXXXXXXXXXXXXXXX Backing plate
           NNNNS=
SSS
            =
;<--=20
Coil -->
           SSSSN=
NNN
XXXXXXXXXXXXXXXXXXXXXXX Backing plate
Bolt           &=
nbsp;            =
;    Bolt
 
    I find that this works very well and it is easy=
 to=20
adjust. The coil that I use came as a spare for a 220V water valve on a wash=
ing=20
machine and it is about 3/8" thick by slightly over 1" OD, about 5,000=20
turns. 
    I use the same layout but with 1"x1/2"x1/4" NdF=
eB=20
magnets for the 1/16" Cu damping plate.
    Any internal field inbalance is shorted through=
 the=20
bolts and the external field is near zero.
 
    Hope that this helps.
 
    Regards,
 
    Chris Chapman