## PSN-L Email List Message

Subject: Re: Did I get 12 second period ?
From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@.........
Date: Mon, 25 May 2009 12:54:38 +0000

```Hi

The floor is level, this is the same floor where I keep my geophone,
with any issues.

However, the lehman sensor appears to be this high so I can get 12 to 20
second period. I am not sure why that is.

The only problem that I am dealing with now is that once I have setup
the correct period. I something find that the coil slides to the magnets
and gets stuck there. I do not know why that movment happens. I am
trying to fix that issue.

Regards.
J=F3n Fr=EDmann.

On sun, 2009-05-24 at 22:48 -0700, Geoffrey wrote:
> It Seems To Me your floor was not level to begin with ?
> You most probably needed an angle of 1 degree or less
> from level ?
> I figure a little over 2 degrees for only 5 seconds
> using trig to figure the effect on the acceleration
> of gravity.
> P=3D2PiSQR(L/g)
> P =3D period in seconds
> Pi =3D 3.121(whatever)
> SQR =3D SQUARE ROOT OF()
> L =3D length of pendulum in inches
> g =3D gravity in inches per (second squared)
> g' =3D SINE or COSINE of the anglular displacement from zero g
>=20
> If you fix L
> at current gravity
> you change angle according to
> SINE or COSINE
> like g sin(angle) relative to horizontal
> or vertical.
> At vertical you got full g
> but at horizontal or inverted its zero.
> Sort of vectored by a lever arm.
> A spring with a linear constant acts
> just like a pendulum.
> If it takes 10 inches to get one second on a
> pendulum it also takes ten inches of extension
> of a spring to get one second.
> Or so it seems to me.
> In Physics class we used this frictionless
> puck floating on a rail at different angles
> to show how it could affect the acceleration.
> Frictionless on a cushion of air.
>=20
>=20
> ----- Original Message -----=20
> From: "J=F3n Fr=EDmann"
> To: "PSN-Postlist"
> Sent: Sunday, May 24, 2009 1:35 PM
> Subject: Did I get 12 second period ?
>=20
>=20
> Hi all
>=20
> I did one little change to my lehman seismometer. I did rase the front
> of the seismomter up from where it was. This appears to have incresed
> it's period to about 12 seconds.
>=20
> Here is are pictures of what I did.
> http://www.jonfr.com/myndir/v/geology/lehman/p5240001.jpg.html
>=20
> I can send psn file to anyone how wants.
>=20
> Regards.

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