Hi Chris,  What sort of "choice of suspension system" would you =
recommend? Is there a detail I can look at?=20
I have only seen the knife edge style.
Thanks, Ted
  ----- Original Message -----=20
  From: ChrisAtUpw@..........
  To: psn-l@.................
  Sent: Saturday, September 23, 2006 5:09 PM
  Subject: Re: Seismograph for school


  In a message dated 23/09/2006, jcpatskan@......... writes:
    I am thinking of trying to build a seismograph for my son's school. =
I have quite a bit of experience in shallow exploration geophysic's, =
mostly electrical and electromagnetic, but none in seismology.  I have =
searched the internet and found quite a few resources.=20
  Hi John,

      You might consider making a medium sized Lehman - about 2 ft long? =
Say about 1.5 sec period that can be extended to 20 sec?

      You will need +/-12V stabilised power supplies of you may buy an =
amplifier and transformer from Larry at http://psn.quake.net

      Since it will be used with other school systems, I suggest that =
you use Amaseis and buy a DI-154 12 bit ADC still at just $39! =
www.dataq.com Amaseis supports this ADC.
      See http://jclahr.com/science/psn/as1/index.html

      Use magnetic damping, NOT oil.

      Use an all metal braced single unit costruction - NO plastic =
structural components - NO separated sections.

      Your choice of suspension system is critical. NEITHER a point on a =
plane NOR knife edge systems are satisfactory - avoid them like the =
plague. Most other systems are OK to good. You need to be able to get a =
period of at least 20 seconds.

      Have a look at =
http://jclahr.com/science/psn/chapman/lehman/index.html
      and http://jclahr.com/science/psn/chapman/index.html
      and http://www.jclahr.com/science/psn/cor_psn.html
      and http://jclahr.com/science/psn/

      ALSO =
http://www.mgm.monschau.de/seismic/english/artikel/artikel_1_4.php and =
sequels

      I have also noticed a seismograph (or strong motion accelerometer) =
on sale at e-bay, with an opening bid of $75. =20
      I suggest that you forget this one! You do not need a strong =
motion sensor - or the headaches of converting an optical one. This =
might be called 'buying trouble'!

      Good Luck!

      Chris Chapman







Hi Chris,  What sort of "choice of suspension system" would =
you=20
recommend? Is there a detail I can look at? 
I have only seen the knife edge style.
Thanks, Ted

  
----- Original Message ----- 
  From:=20
  ChrisAtUpw@....... 
  
To: psn-l@.............. 
  
Sent: Saturday, September 23, =
2006 5:09=20
  PM
  
Subject: Re: Seismograph for =
school
  


  
In a message dated 23/09/2006, jcpatskan@......... =
writes:
  I am=20
    thinking of trying to build a seismograph for my son's =
school. I have=20
    quite a bit of experience in shallow exploration geophysic's, mostly =

    electrical and electromagnetic, but none in seismology.  I have =

    searched the internet and found quite a few resources. =

  
Hi John,
  
 
  
    You might consider making a medium sized =
Lehman -=20
  about 2 ft long? Say about 1.5 sec period that can be extended to 20=20
sec?
  
 
  
    You will need +/-12V stabilised power =
supplies of=20
  you may buy an amplifier and transformer from Larry at http://psn.quake.net
  
 
  
    Since it will be used with other school =
systems,=20
  I suggest that you use Amaseis and buy a DI-154 =
12 bit=20
  ADC still at just $39! www.dataq.com Amaseis supports this =
ADC.
  
    See http://jclahr.com/s=
cience/psn/as1/index.html
  
 
  
    Use magnetic damping, NOT oil.
  
 
  
    Use an all metal braced single unit =
costruction -=20
  NO plastic structural components - NO separated sections.
  
 
  
    Your choice of suspension system is critical. =
NEITHER=20
  a point on a plane NOR knife edge systems are satisfactory - avoid =
them like=20
  the plague. Most other systems are OK to good. You need to be able to =
get a=20
  period of at least 20 seconds.
  
 
  
    Have a look at http://j=
clahr.com/science/psn/chapman/lehman/index.html
  
    and http://jclahr.c=
om/science/psn/chapman/index.html
  
    and http://www.jclahr=
..com/science/psn/cor_psn.html
  
    and http://jclahr.com/science/psn/
  
 
  
    ALSO http://www.mgm.monschau.de/seismic/english/artikel/artikel_1_4.php=
 and=20
  sequels
  
 
  
    I have also noticed a=20
  seismograph (or strong motion accelerometer) on =
sale at=20
  e-bay, with an opening bid of $75.  
  

  
    I suggest that you =
forget=20
  this one! You do not need a strong motion sensor - or the =
headaches of=20
  converting an optical one. This might be called 'buying =
trouble'!
  
 
  
    Good Luck!
  
 
  
    Chris Chapman