Jon,
=A0=A0=A0=A0=A0 I found it very confusing when setting the period for my se=
ismograph, and for a=20
long time took the period to be the time it takes the arm to swing from one=
 side to the
other.( I could never get much more than 10 seconds)!!.
=A0But apparently I am wrong, The period is the time it takes for the arm t=
o swing
past the same point in the same direction twice. So if you hold the arm tow=
ards you
=A0and let it go, as it passes the centre, start a stopwatch, then let=A0th=
e arm=A0go to the other side,
then back towards you , and as it passes the centre again press stop. This =
is the period.
=A0 Anyone please correct me if I am wrong. !!.
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 James

--- On Fri, 8/5/09, J=F3n Fr=EDmann  wrote:

From: J=F3n Fr=EDmann 
Subject: Re: Incresing the period of a lehmans seismomter ?
To: psn-l@..............
Date: Friday, 8 May, 2009, 2:08 AM

Hi all

I got the period down to 6 seconds at the lower end, but at 4 seconds
the high end. But I have to do it adjust the period really slowly. I am
not sure what I can detect at 6 seconds.

Geoffrey, I know what you mean. I am trying to understand something in a
diffrent language and am trying to understand something that I have not
got a big traning on.

Regards.
J=F3n Fr=EDmann.

On fim, 2009-05-07 at 17:04 -0700, Geoffrey wrote:
> Gee, I believe this to be one of those
> garden gate seismometers.
> I always thought of it as a modified
> pendulum changing the acceleration of gravity
> in a trigonometric fashion.
> This means the mass is the lowest point on the lever arm
> or you can not have stability.
> It manipulates the pull of gravity
> like Sine or Cosine of the angle relative
> to horizontal.
> I believe you guys are thinking much more
> complex then myself.
> You more than likely will never
> take souls like me very serious.
> Sort of like Rodney Dangerfield ???
>=20
> ----- Original Message -----=20
> From: "J=F3n Fr=EDmann" 
> To: "PSN-Postlist" 
> Sent: Wednesday, May 06, 2009 7:54 PM
> Subject: Incresing the period of a lehmans seismomter ?
>=20
>=20
> Hi all
>=20
> Tomorrow I am going to make the final changes to my lehman seismomter. I
> hope that this changes make the seismomter get down to 20 seconds period
> at most.
>=20
> The only thing that I need to know is this. What is the best way to
> increase the period of my lehman seismomter ? Moving the boom down or
> up ? Or do I have to do something else.
>=20
> Regards.

__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

Jon,
      I found it very confusing when setting =
the period for my seismograph, and for a 
long time took the period to be the time it takes the arm to swing fro=
m one side to the
other.( I could never get much more than 10 seconds)!!.
 But apparently I am wrong, The period is the time it takes for t=
he arm to swing
past the same point in the same direction twice. =
So if you hold the arm towards you
 and let it go, as it passes the centre, start a stopwatch, then =
let the arm go to the other side,
then back towards you , and as it passes the centre again press stop. =
This is the period.
  Anyone please correct me if I am wrong. !!.
           &nbs=
p;            &=
nbsp;           &nbs=
p;            &=
nbsp;           &nbs=
p;  James

--- On Fri, 8/5/09, J=F3n Fr=EDmann <jonfr@j=
onfr.com> wrote:

From: J=F3n Fr=EDmann <jonfr@.........>
Subj=
ect: Re: Incresing the period of a lehmans seismomter ?
To: psn-l@webtro=
nics.com
Date: Friday, 8 May, 2009, 2:08 AM

Hi all

I got the period down to 6 seconds at the lower end, but at 4 seconds
the high end. But I have to do it adjust the period really slowly. I am
not sure what I can detect at 6 seconds.

Geoffrey, I know what you mean. I am trying to understand something in a
diffrent language and am trying to understand something that I have not
got a big traning on.

Regards.
J=F3n Fr=EDmann.

On fim, 2009-05-07 at 17:04 -0700, Geoffrey wrote:
> Gee, I believe this to be one of those
> garden gate seismometers.
> I always thought of it as a modified
> pendulum changing the acceleration of gravity
> in a trigonometric fashion.
> This means the mass is the lowest point on the lever arm
> or you can not have stability.
> It manipulates the pull of gravity
> like Sine or Cosine of the angle relative
> to horizontal.
> I believe you guys are thinking much more
> complex then myself.
> You more than likely will never
> take souls like me very serious.
> Sort of like Rodney Dangerfield ???
>=20
> ----- Original Message -----=20
> From: "J=F3n Fr=EDmann" <jonfr@.........>
> To: "PSN-Postlist" <PSN-L@..............>
> Sent: Wednesday, May 06, 2009 7:54 PM
> Subject: Incresing the period of a lehmans seismomter ?
>=20
>=20
> Hi all
>=20
> Tomorrow I am going to make the final changes to my lehman seismomter.=
 I
> hope that this changes make the seismomter get down to 20 seconds peri=
od
> at most.
>=20
> The only thing that I need to know is this. What is the best way to
> increase the period of my lehman seismomter ? Moving the boom down or
> up ? Or do I have to do something else.
>=20
> Regards.

__________________________________________________________

Public Seismic Network Mailing List (PSN-L)


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