Hi Everyone,  I did find some 38 gauge magnet wire, but thought you =
might like to see this on ebay.  37 gauge Item number: 290035960569 one =
pound.

Thanks, Ted

  ----- Original Message ----- From: ChrisAtUpw@..........
  To: psn-l@.................
  Sent: Tuesday, October 03, 2006 9:23 PM
  Subject: Re: Building a lehman seismometer


  In a message dated 2006/10/04, jonfr500@......... writes:


    I also plan to build a Lehman seismometer, if I can keep it small =
enough. But I need a suggestion for material and some mesurements and =
proper drawings before I can start. I also want to keep the frequency of =
the Lehman seismometer around 1Hz.


  Hi Jon,=20

         The  whole point about a Lehman type seismometer is that you =
take a pedulum which would have a period of about 1.3 to 1.5 sec if =
mounted vertically and extend the period to maybe 20 sec. The sensor =
will respond from 20 sec to the 10 Hz of your amplifier filter. I =
suspect that an arm of between 45 and 60 cm would be fine for you. Don't =
try to make it smaller. This should pick up your seismic signals very =
well.

         I make a T / L frame with U channel Al with 5 mm Al plate for =
the corner supports. I don't know what materials are available to you. =
You can use 50 x 25 mm, but I prefer 75 x 25 mm section.

         Regards,








Hi Everyone,  I did find some 38 =
gauge magnet=20
wire, but thought you might like to see this on ebay.  37 gauge =
Item=20
number: 290035960569 one pound.
 
Thanks, Ted
 

  
----- Original Message ----- =
From: ChrisAtUpw@....... 
  
To: psn-l@.............. 
  
Sent: Tuesday, October 03, 2006 =
9:23=20
  PM
  
Subject: Re: Building a lehman=20
  seismometer
  

In a=20
  message dated 2006/10/04, jonfr500@......... =
writes:


  I also plan to build a Lehman seismometer, if I can keep =
it=20
    small enough. But I need a suggestion for material and some =
mesurements and=20
    proper drawings before I can start. I also want to keep the =
frequency of the=20
    Lehman seismometer around 1Hz.

Hi Jon,=20
  

       The  whole point =
about a=20
  Lehman type seismometer is that you take a pedulum which would have a =
period=20
  of about 1.3 to 1.5 sec if mounted vertically and extend the period to =
maybe=20
  20 sec. The sensor will respond from 20 sec to the 10 Hz of your =
amplifier=20
  filter. I suspect that an arm of between 45 and 60 cm would be fine =
for you.=20
  Don't try to make it smaller. This should pick up your seismic signals =
very=20
  well.

       I make a T / L frame =
with U=20
  channel Al with 5 mm Al plate for the corner supports. I don't know =
what=20
  materials are available to you. You can use 50 x 25 mm, but I prefer =
75 x 25=20
  mm section.

      =20
  Regards,

       Chris Chapman=20