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#248
Thanks for sending this Dale. Could someone please send me the
diagram. For some reason I'm missing the first couple of posts in
this series. Also, where is "Jim Koehler's Proton Precession
Magnetometers" where the spreadsheet tables were found? Maybe this
thread will make sense to me now.
Thanks,
Charles
> The Proton Mag Forum[Consult the original if any questions because I could
have made errors in transcription - das]
>
> BIFILAR WINDINGS
>
> POSTING #226.
>
> When I was using the spreadsheet tables in Jim Koehler's "Proton Precession
Magnetome-
> ters") I noted that for any fixed size of fluid container; as the number of
turns of
> any given wire size increased the signal level increased because of the
increased in-
> ductance and coupling. At the same time the polarization current, of course,
de-
> creased because of the increased inductance and coupling. At the same time,
the po-
> larization current, decreased due to the increased resistance of the longer
wire. I
> also noted that for any given wire size if I could double the polarization
current for
> the same number of turns I would get a substantial increase in the signal to
noise ra-
> tio.
>
> This can be simply accomplished by using bifilar windings. That is, two
windings are
> applied at the same time. The switching is a bit more complicated and
requires 4 FORM
> C contacts rated in excess of the expected forward and backward currents.
The sche-
> matic below shows the switching arrangement. Polarization current is applied
to the
> two windings in parallel thus halving the resistance of the sensor. This
will double
> the polarization current thus increasing precession probability. The net
result is a
> stronger signal and a much improved signal to noise ratio.
>
> The two coils are then connected in series for the detection cycle giving the
sensi-
> tivity associated with the larger number of turns. Trifiliar and even more
numerous
> windings are possible but there is a practical limit.
>
> (Diagram in the original is at this point.)
>
> Take care with polarity. Lee Fraser.
>
Thanks for sending this Dale. Could someone please send me the
diagram. For some reason I'm missing the first couple of posts in
this series. Also, where is "Jim Koehler's Proton Precession
Magnetometers" where the spreadsheet tables were found? Maybe this
thread will make sense to me now.
Thanks,
Charles
> The Proton Mag Forum[Consult the original if any questions because I could
have made errors in transcription - das]
>
> BIFILAR WINDINGS
>
> POSTING #226.
>
> When I was using the spreadsheet tables in Jim Koehler's "Proton Precession
Magnetome-
> ters") I noted that for any fixed size of fluid container; as the number of
turns of
> any given wire size increased the signal level increased because of the
increased in-
> ductance and coupling. At the same time the polarization current, of course,
de-
> creased because of the increased inductance and coupling. At the same time,
the po-
> larization current, decreased due to the increased resistance of the longer
wire. I
> also noted that for any given wire size if I could double the polarization
current for
> the same number of turns I would get a substantial increase in the signal to
noise ra-
> tio.
>
> This can be simply accomplished by using bifilar windings. That is, two
windings are
> applied at the same time. The switching is a bit more complicated and
requires 4 FORM
> C contacts rated in excess of the expected forward and backward currents.
The sche-
> matic below shows the switching arrangement. Polarization current is applied
to the
> two windings in parallel thus halving the resistance of the sensor. This
will double
> the polarization current thus increasing precession probability. The net
result is a
> stronger signal and a much improved signal to noise ratio.
>
> The two coils are then connected in series for the detection cycle giving the
sensi-
> tivity associated with the larger number of turns. Trifiliar and even more
numerous
> windings are possible but there is a practical limit.
>
> (Diagram in the original is at this point.)
>
> Take care with polarity. Lee Fraser.
>