PSN-L Email List Message

Subject: Re: Changes to my Lehman sensor
From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@.........
Date: Wed, 08 Apr 2009 00:57:11 +0000


I will change the wire layout when I get the new arm. I was adviced to
keep the coil on the arm, not the base it self.

The natrual period of the sensor as it was setup was around 0.3Hz. But
it's range was only limited to that.

J=F3n Fr=EDmann.

On mi=F0, 2009-04-08 at 06:43 +1000, Dave Nelson wrote:
> Hi Jon,
>                 having iron in that area within the field of the magnet i=
> not a good idea
> you would be much better off to use brass  if you didnt want to use alumi=
>     I also notice from your photo's that your pickup wire from the coil
> a rather heavy looking wire will also affect the movement of the arm.  Th=
> usual
> practice, if  a person insists of putting the coil on the arm, is to=20
> terminate the
> heavier wire at the pivot end of the arm and to use VERY FINE  from that=20
> termination,  say 24-28 SWG enamelled wire wound in a loose coil say ~ 5 =
>   of pencil/ pen diameter, then terminate that fine wire on the base of t=
> seismom.
> and then run heavier wire  again to the electronics.
> I can almost guarantee that the way you have taken your wire off the arm=20
> will have
> a serious effect on the free movement of the arm!
> Dave N
> Sydney
> At 07:32 PM 4/7/2009 +0000, you wrote:
> >Hi
> >I belive that I found the last problem (according to the idea). The last
> >problem is the alunium rod that I have used as an arm. I belive that it
> >was too soft to work properly and because of that I didn't behave
> >correctly.
> >I am going to replace it with iron based arm and there is going to be a
> >steel based end on it. I hope that gives me the resault that I want.
> >Regards.
> >J=F3n Fr=EDmann.
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