## PSN-L Email List Message

Subject: Re: Measuring Newtons/Amp
From: ChrisAtUpw@.......
Date: Wed, 26 Nov 2008 19:49:04 EST

```
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

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:
<=
FONT=20
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,=
=20
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
```