In a message dated 27/11/2008 00:06:02 GMT Standard Time,  
gel@................. writes:

I put  together a web page that describes my process for measuring the 
parameter,  newtons/amp for 3 different coil and magnet assemblies. Check out 
_http://sites.google.com/site/seismicsensorinfo/meas-newtons-per-amp_ 
(http://sites.google.com/site/seismicsensorinfo/meas-newtons-per-amp)  


Hi Gary,
 
    I suggest that you use the smaller coil former, but  substitute 36 gauge 
wire to give maybe 1500 turns. You want to keep the DC coil  resistance below 
about 200 Ohms. This should give you about 35 N / Amp.
 
    The relatively low figure that you got for the  large coil is due to the 
lower magnetic field of the quad 1/8" magnets. You  could probably triple the 
force with thicker magnets, but you are limited  by the thickness of the iron 
backing plates. They are already near saturation  with the 1" square magnets.
 
    I can't see a DVM in our photo? You need an  accurate meter to measure 
the current.
 
    Regards,
 
    Chris Chapman






In a message dated 27/11/2008 00:06:02 GMT Standard Time,=20
gel@................. writes:
<=
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  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>I put=20
  together a web page that describes my process for measuring the parameter,=
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  newtons/amp for 3 different coil and magnet assemblies. Check out http://sites.google.com/site/seismicsensorinfo/meas-newtons-per-amp&n=
bsp;

Hi Gary,
 
    I suggest that you use the smaller coil former,=
 but=20
substitute 36 gauge wire to give maybe 1500 turns. You want to keep the DC c=
oil=20
resistance below about 200 Ohms. This should give you about 35 N / Amp.
 
    The relatively low figure that you got for=
 the=20
large coil is due to the lower magnetic field of the quad 1/8" magnets. You=20
could probably triple the force with thicker magnets, but you are limit=
ed=20
by the thickness of the iron backing plates. They are already near saturatio=
n=20
with the 1" square magnets.
 
    I can't see a DVM in our photo? You need an=20
accurate meter to measure the current.
 
    Regards,
 
    Chris Chapman