Thanks, Folks, Yes this was the image I had seen before.   Thanks also =
for the various references.
Ted
  ----- Original Message -----=20
  From: meredith lamb=20
  To: psn-l@.................
  Sent: Thursday, October 02, 2008 6:47 PM
  Subject: Re: Re:


  Hi Ted,

  The "concept" or diagram you mention is possibly this:

  http://physics.mercer.edu/petepag/tilt.gif

  which is a part of:

  http://physics.mercer.edu/petepag/tiltm.html

  and the title of the above is "Tiltmeters and Angle Measuring =
Equipment" by Randall Peters

  but....I suppose you've already found such from Chris's reference.

  Take care, Meredith


  =20
  On Thu, Oct 2, 2008 at 5:11 PM,  wrote:

    Meredith,  Thank you for your reply and encouragement.   The first =
sensor I spoke of was about 8 foot tall and the boom was about 4 foot, =
two feet on each side of the ribbon.
    I did not keep my notes on this unit but remember the period was =
massive, just moving the masses further out on the boom.

    This present unit is only about 36" tall and the boom, one side of =
the ribbon only is about 6".   I used a SS thin wire instead of the band =
saw blade ribbon.   At this point I think it will respond similar to a =
Lehman with a 5 second period.  So far it behaves, just like my Lehman.

    I will let you know, if it works and send or post the .psn.          =
   It looks promising, very simple and if it works I will rebuild it =
targeting a 20 second period.

    Cheers, Ted    ps..............On some web site I saw the concept of =
a Torsion Spring Long Period, illustrated as a box with a vertical =
torsion spring in the center of the box, and a boom............but the =
entire box was tipped, to illustrate the vertical wire/spring needed to =
be off vertical, not unlike the Lehman
      ----- Original Message -----=20
      From: meredith lamb=20
      To: psn-l@.................
      Sent: Thursday, October 02, 2008 3:29 PM
      Subject: Re:


      Hi Ted,

      Sorry...I couldn't find anything along the specific line you =
mention either..especially the flat ribbon spring variety.  If I read =
you email right;
      the very height you're using makes it a "giant" representation; =
and that likely makes it much more responsive as you're seeing, and
      to be fair the stresses involved will likely show all kinds of =
metal/structure creep over time which you'll have to adjust for.

      A lot of the web sites I've seen, go out of their way to describe =
such as antiquated, obsolete, old etc; which is true in the sense
      of what is predominately used now.  On the other hand, the torsion =
aspect really "does away" with a few of the normal pesky pivot problems
      that are found in other seismometers/tiltmeters; and that alone is =
a good adjustment and/or labor saving positive.

      Yes indeed...explore away.....there is likely a world of different =
flat ribbon or round wire sizes material one could try.

      Take care, Meredith
        =20

      On Wed, Oct 1, 2008 at 10:38 PM,  wrote:

        I am exploring the subject of a torsion spring sensor again.  I =
say again because I have tried this approach before with no success at =
all.
        I took a long band saw blade cut it to form a long vertical =
torsion spring. Attached both ends and pulled it tight.
        In the middle of this spring I attached a boom. On both ends of =
the boom I attached a mass of equal value.
        This boom would move around the vertical axis with very little =
effort, twisting the spring and then reversing to the other direction, =
rocking back and forth for a very long time.  I don't remember how long =
but I think it was one hour plus.
        The period of oscillation was controlled by moving the masses =
further out on the boom.   Very long periods 30 seconds plus.  To make a =
long story short, it did not record any earthquakes.

        I think I did two things wrong.  1. The booms of equal mass =
cancelled the movement of each other. And in this configuration the =
earthquake would need to spin the house to move the masses.
        2. The torsion spring needed to be tipped, not vertical.

        Here is my next attempt.   1.  I removed the boom, which formed =
a (+) on the vertical torsion spring and replace it with a short =
pendulum boom, this time on one side only.=20
        it looks like a T on its side ( l-)
        2.  I contained the vertical torsion spring in a strong box =
about 12"x12"x36".  This retains all the parts and I can add tension to =
the spring, and mount the magnet and coil
        3.  I placed three leveling legs on the base of the box.  Now I =
can tip the vertical spring (Off Vertical).    Similar to tipping a =
Lehman, pitching up or down.
        The spring now at an angle, contains a pendulum which is now =
(Off Horizontal).

        The pendulum I am using is only about 6" long, and I get a =
period of about 5 seconds. I could get 20 seconds with a 18" boom. But =
my box could only accommodate a 6" boom.

         It is now running as a test......I will see if it will record =
earthquakes.
        It is sensitive to me moving around the room, and to drafts and =
tilts.

        I have seen something similar somewhere on the web, but I can't =
fine it.   This is all I could find.   If someone has tried this please =
email me.   Thanks, Ted

        Torsion Seismometer Wood Anderson


        http://www.data.scec.org/Module/s3inset3.html










Thanks, Folks, Yes this was the image I =
had seen=20
before.   Thanks also for the various references.
Ted

  
----- Original Message ----- 
  From:=20
  meredith lamb 
  
To: psn-l@.............. 
  
Sent: Thursday, October 02, =
2008 6:47=20
  PM
  
Subject: Re: Re:
  


  

  
Hi Ted,
  
 
  
The "concept" or diagram you mention is possibly this:
  
 
  
http://physics.mercer=
..edu/petepag/tilt.gif
  
 
  
which is a part of:
  
 
  
http://physics.merc=
er.edu/petepag/tiltm.html
  
 
  
and the title of the above is "Tiltmeters and Angle Measuring =
Equipment"=20
  by Randall Peters
  
 
  
but....I suppose you've already found such from Chris's =
reference.
  
 
  
Take care, Meredith
  


 
  
On Thu, Oct 2, 2008 at 5:11 PM, <tchannel1@............>=20
  wrote:

  

    

    
Meredith,  Thank you for your =
reply and=20
    encouragement.   The first sensor I spoke of was about 8 =
foot tall=20
    and the boom was about 4 foot, two feet on each side of the=20
    ribbon.
    
I did not keep my notes on this =
unit but=20
    remember the period was massive, just moving the masses further out =
on the=20
    boom.
    
 
    
This present unit is only about 36" =
tall and=20
    the boom, one side of the ribbon only is about 6".   I =
used a SS=20
    thin wire instead of the band saw blade ribbon.   At this =
point I=20
    think it will respond similar to a Lehman with a 5 second =
period.  So=20
    far it behaves, just like my Lehman.
    
 
    
I will let you know, if it works =
and send or=20
    post the=20
    =
..psn.           &n=
bsp;=20
    It looks promising, very simple and if it works I will rebuild it =
targeting=20
    a 20 second period.
    
 
    
Cheers, Ted   =20
    ps..............On some web site I saw the concept of a Torsion =
Spring Long=20
    Period, illustrated as a box with a vertical torsion spring in the =
center of=20
    the box, and a boom............but the entire box was tipped, to =
illustrate=20
    the vertical wire/spring needed to be off vertical, not unlike the=20
    Lehman
    

    

    

    

      
----- Original Message ----- =

      
From: =
meredith lamb 
      
To: psn-l@..............=20
      
      
Sent: Thursday, October 02, =
2008 3:29=20
      PM
      
Subject: Re:
      


      
Hi Ted,

Sorry...I couldn't find anything =
along the=20
      specific line you mention either..especially the flat ribbon =
spring=20
      variety.  If I read you email right;
the very height =
you're using=20
      makes it a "giant" representation; and that likely makes it much =
more=20
      responsive as you're seeing, and
to be fair the stresses =
involved will=20
      likely show all kinds of metal/structure creep over time which =
you'll have=20
      to adjust for.

A lot of the web sites I've seen, go out of =
their=20
      way to describe such as antiquated, obsolete, old etc; which is =
true in=20
      the sense
of what is predominately used now.  On the other =
hand,=20
      the torsion aspect really "does away" with a few of the normal =
pesky pivot=20
      problems
that are found in other seismometers/tiltmeters; and =
that=20
      alone is a good adjustment and/or labor saving =
positive.

Yes=20
      indeed...explore away.....there is likely a world of different =
flat ribbon=20
      or round wire sizes material one could try.

Take care,=20
      Meredith
   

      
On Wed, Oct 1, 2008 at 10:38 PM, <tchannel1@............> wrote:

      

        

        
I am exploring the subject of a =
torsion=20
        spring sensor again.  I say again because I have tried this =

        approach before with no success at all.
        
I took a long band saw blade =
cut it to form=20
        a long vertical torsion spring. Attached both ends and pulled it =

        tight.
        
In the middle of this spring I =
attached a=20
        boom. On both ends of the boom I attached a mass of equal=20
        value.
        
This boom would move around the =
vertical=20
        axis with very little effort, twisting the spring and then =
reversing to=20
        the other direction, rocking back and forth for a very long =
time. =20
        I don't remember how long but I think it was one hour =
plus.
        
The period of oscillation =
was=20
        controlled by moving the masses further out on the =
boom.  =20
        Very long periods 30 seconds plus.  To make a long story =
short, it=20
        did not record any earthquakes.
        
 
        
I think I did two things =
wrong.  1.=20
        The booms of equal mass cancelled the movement of each =
other. And=20
        in this configuration the earthquake would need to spin =
the house=20
        to move the masses.
        
2. The torsion spring needed to =
be tipped,=20
        not vertical.
        
 
        
Here is my next =
attempt.  =20
        1.  I removed the boom, which formed a (+) on the vertical =
torsion=20
        spring and replace it with a short pendulum boom, this time on =
one side=20
        only. 
        
it looks like a T on its side ( =

        l-)
        
2.  I contained the =
vertical torsion=20
        spring in a strong box about 12"x12"x36".  This retains all =
the=20
        parts and I can add tension to the spring, and mount the magnet =
and=20
        coil
        
3.  I placed three =
leveling legs on=20
        the base of the box.  Now I can tip the vertical =
spring (Off=20
        Vertical).    Similar to tipping a Lehman, =
pitching up or=20
        down.
        
The spring now at an angle, =
contains a=20
        pendulum which is now (Off Horizontal).
        
 
        
The pendulum I am using is only =
about 6"=20
        long, and I get a period of about 5 seconds. I could get 20 =
seconds=20
        with a 18" boom. But my box could only accommodate a 6"=20
        boom.
        
 
        
 It is now running as a =
test......I=20
        will see if it will record earthquakes.
        
It is sensitive to me moving =
around the=20
        room, and to drafts and tilts.
        
 
        
I have seen something similar =
somewhere on=20
        the web, but I can't fine it.   This is all I could=20
        find.   If someone has tried this please email =
me.  =20
        Thanks, Ted
        
 
        
Torsion Seismometer Wood=20
        Anderson
        
 
        
 
        
http://www.data.scec.org/Module/s3inset3.html<=
/DIV>