PSN-L Email List Message
Subject: Re: Incresing the period of a lehmans seismomter ?
Date: Sat, 9 May 2009 17:36:10 -0700 (GMT-07:00)
Try using a bubble level to know when the boom is level. Then tilt the end =
of the boom down, never up. I normally start by using a level to make sure =
the vertical upright is at zero degrees and then I level the boom. I then a=
dd about 1-5 degree of tile in the upper most point of the upright in the =
direction of the boom. I have three level screws the base plate and a machi=
ne screw in the end of the boom to make the adjustment.=20
Regards, Stve Hammond PSN San Jose Aptos, CA
>From: J=C3=B3n Fr=C3=ADmann
>Sent: May 9, 2009 4:28 PM
>Subject: Re: Incresing the period of a lehmans seismomter ?
>Thanks for the help of the weeks. I could not have fixed the issues with
>out you all.
>I am still having minor issues adjusting the period of my lehman sensor.
>I am not sure if I have to move the boom up or down to increase the
>period of my sensor.
>On f=C3=B6s, 2009-05-08 at 05:41 +0000, JAMES RIDOUT wrote:
>> I found it very confusing when setting the period for my
>> seismograph, 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)!!.
>> But apparently I am wrong, The period is the time it takes for the
>> 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. !!.
>> --- On Fri, 8/5/09, J=C3=B3n Fr=C3=ADmann wrote:
>> From: J=C3=B3n Fr=C3=ADmann
>> 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 se=
>> the high end. But I have to do it adjust the period really slowl=
y. I am
>> not sure what I can detect at 6 seconds.
>> Geoffrey, I know what you mean. I am trying to understand someth=
ing in a
>> diffrent language and am trying to understand something that I h=
>> got a big traning on.
>> J=C3=B3n Fr=C3=ADmann.
>> 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 ???
>> > ----- Original Message -----=20
>> > From: "J=C3=B3n Fr=C3=ADmann"
>> > To: "PSN-Postlist"
>> > Sent: Wednesday, May 06, 2009 7:54 PM
>> > Subject: Incresing the period of a lehmans seismomter ?
>> > Hi all
>> > Tomorrow I am going to make the final changes to my lehman sei=
>> > hope that this changes make the seismomter get down to 20 seco=
>> > at most.
>> > The only thing that I need to know is this. What is the best w=
>> > increase the period of my lehman seismomter ? Moving the boom =
>> > up ? Or do I have to do something else.
>> > Regards.
>> Public Seismic Network Mailing List (PSN-L)
>> To leave this list email PSN-L-REQUEST@.............. with
>> the body of the message (first line only): unsubscribe
>> See http://www.seismicnet.com/maillist.html for more information=
>Public Seismic Network Mailing List (PSN-L)
>To leave this list email PSN-L-REQUEST@.............. with
>the body of the message (first line only): unsubscribe
>See http://www.seismicnet.com/maillist.html for more information.
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