PSN-L Email List Message

Subject: Re: Verticle Sensor Design
From: Barry Lotz barry_lotz@.............
Date: Fri, 22 Aug 2008 19:10:35 -0700 (PDT)


Hi Gary
  I made two modest versions of Sean Thomas Morrissey's design, a 30" and a smaller 12" version. I have a few pictures of the 30" sensor on my beginning website www.seismicvault.com .  As you can see there is some corrosion from the mild steel I used in certain locations. It's not the prettiest sensor but I have had very good response from it (prototype). The leaf spring is somewhat temperature sensitive so I installed a coil spring compensation made from a bimetal thermometer. I used an LVDT in the one pictured but I used a vrdt and feedback coil per STM in the 12" version. His descriptions and fabrication notes are very helpful. I run the sensor position output to a digital voltmeter in the house. With bumps of a push button switch I can keep the sensor fairly well centered with the balancing motor from Edward Scientific. Maybe some day Larry will have a multichannel 8 bit ADC and DAC included in a future design so balancing could be done in software. (hint, hint)
  Barry
   
  

ChrisAtUpw@....... wrote:
  In a message dated 2008/08/22, gel@................. writes:

  Not to long ago someone mentioned a good design for a vertical seismometer. Is there a picture handy and some words of advice.

Hi Gary,

       I think that this was on Sean Morrissey's old website. See 
       http://www.bryantlabs.net/seismo.html
       The original plans, circuits, other details of the STM-8 are on http://www.eas.slu.edu/People/STMorrissey/index.html

       See also http://jclahr.com/science/psn/hill/index.html

       Regards,

       Chris Chapman 
Hi Gary
I made two modest versions of Sean Thomas Morrissey's design, a 30" and a smaller 12" version. I have a few pictures of the 30" sensor on my beginning website www.seismicvault.com .  As you can see there is some corrosion from the mild steel I used in certain locations. It's not the prettiest sensor but I have had very good response from it (prototype). The leaf spring is somewhat temperature sensitive so I installed a coil spring compensation made from a bimetal thermometer. I used an LVDT in the one pictured but I used a vrdt and feedback coil per STM in the 12" version. His descriptions and fabrication notes are very helpful. I run the sensor position output to a digital voltmeter in the house. With bumps of a push button switch I can keep the sensor fairly well centered with the balancing motor from Edward Scientific. Maybe some day Larry will have a multichannel 8 bit ADC and DAC included in a future design so balancing could be done in software. (hint, hint)
Barry
 


ChrisAtUpw@....... wrote:
In a message dated 2008/08/22, gel@................. writes:

Not to long ago someone mentioned a good design for a vertical seismometer. Is there a picture handy and some words of advice.


Hi Gary,

       I think that this was on Sean Morrissey's old website. See
       http://www.bryantlabs.net/seismo.html
       The original plans, circuits, other details of the STM-8 are on

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