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. 
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_ (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_ 
(http://www.dataq.com)  Amaseis supports this ADC.
    See _http://jclahr.com/science/psn/as1/index.html_ 
(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_ 
(http://jclahr.com/science/psn/chapman/lehman/index.html) 
    and _http://jclahr.com/science/psn/chapman/index.html_ 
(http://jclahr.com/science/psn/chapman/index.html) 
    and _http://www.jclahr.com/science/psn/cor_psn.html_ 
(http://www.jclahr.com/science/psn/cor_psn.html) 
    and _http://jclahr.com/science/psn/_ (http://jclahr.com/science/psn/) 
 
    ALSO _http://www.mgm.monschau.de/seismic/english/artikel/artikel_1_4.php_ 
(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.  

    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
 





In a message dated 23/09/2006, jcpatskan@......... writes:
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  thinking of trying to build a seismograph for my son's school. I have=
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  quite a bit of experience in shallow exploration geophysic's, mostly=20
  electrical and electromagnetic, but none in seismology.  I have searc=
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  the internet and found quite a few resources. 
Hi John,
 
    You might consider making a medium sized Lehman=
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about 2 ft long? Say about 1.5 sec period that can be extended to 20 sec?
 
    You will need +/-12V stabilised power supplies=20=
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you may buy an amplifier and transformer from Larry at http://psn.quake.net
 
    Since it will be used with other school systems=
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suggest that you use Amaseis and buy a DI-154 12 bit A=
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still at just $39! www.dataq.com Amaseis supports this ADC.
    See http://jclahr.com/scie=
nce/psn/as1/index.html
 
    Use magnetic damping, NOT oil.
 
    Use an all metal braced single unit costruction=
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NO plastic structural components - NO separated sections.
 
    Your choice of suspension system is critical. NEITHE=
R a=20
point on a plane NOR knife edge systems are satisfactory - avoid them like t=
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plague. Most other systems are OK to good. You need to be able to get a peri=
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of at least 20 seconds.
 
    Have a look at http://jcla=
hr.com/science/psn/chapman/lehman/index.html
    and http://jclahr.com/=
science/psn/chapman/index.html
    and http://www.jclahr.co=
m/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=20
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