In a message dated 06/02/2010, gmvoeth@........... writes:
What i=20
mean is a coil like a center tapped inductor
+.......|
=
=20
C
O
Gnd.....|
=
=20
I
L
-.......|
CO=
part=20
and the IL part have to be identical. I do not know if you can wind such=
a=20
thing all at once or need two identical yet seperate coil magnet=20
assemblies.
Hi Geoff,
You can wind it quite easily using two supply=
reels=20
winding on both wires at the same time.
Forget=20
the amplifier part altogether, use what you want.
The ordinary single opamp with four resistors=
will=20
allow you to wind a single coil and use an amplifier of that type.
I have=20
never built such a singular thing and can only guess where to begin.
=
I=20
do know that inital signal strength and signal to noise ratio is paramou=
nt for=20
any sensor at all and not just for areas of our own interest.
Eas=
iest=20
way to get a good signal to noise ratio seems to be to use a two ton (av=
d.)=20
mass instead of a two pound (avd.) one. The highest density material you=
can=20
afford.
That is not neccessary or desirable.
Superconducting wire sounds ideal yet none=
at room temp as far as I=20
know.
There is none and unlikely to be any in the=
=20
future.
At the=20
moment i am thinking two of your coil/magnet ideas in additive fashion=
=20
connected to the same mass.
Two coils should double the signal right=
from=20
the start. Four would quadruple it.
You usually do better by doubling the number=
of=20
turns on a coil. A large increase in the output can be readily achieved by=
using=20
thicker NdFeB magnets, rather than by using more turns on the coil. The li=
mit is=20
set by diamagnetic forces on the copper wire at the edges of the magnets.=
Copper=20
wire varies in it's magnetic properties.
If you use a true differential amplifier like=
the=20
INA118 with a double wound coil, you can use finer wire since the coil=20
resistance is not so important. Calculate the kT noise voltage in the coil=
..=20
Regards,
Chris=20
Chapman