PSN-L Email List Message

Subject: Re: AS1 Seismic System
From: Stephen Mortensen mortskm@.......
Date: Sun, 09 Jul 2000 11:08:27 -0700

The Lahrs wrote:

> For a preliminary look at this turn-key system, see:
> Cheers,
> John
> John C. Lahr
> 1925 Foothills Road
> Golden, CO 80402
> (303) 215-9913
> john@........

I checked the AS1 site above and was interested in the filter that extends the
response of the 1.5 natural period to 20 sec,,,,,,    How would it be configured
to do that????               I spent a couple of hours trying to find the answer
in the PSN archives and found a separate add on  but didn't notice any add on   on
the simple diagram or photos of the AS1.
For the moment I'm using an  STM-8 without the feedback,,,,    simple coil and
magnet and oil damping,,,     it has a natural period of about 4 to 5 seconds.
It would be interesting to see if I can extend the response to 20 or 30 seconds
with a filter,,    until I get the force feedback built.          Is the coil in
an active filter loop,,,,   etc??     Can someone point me to a schematic, a link,
an archive,,,  etc     for the way it could be configured and how would you
determine the part values for a given period??

Thanks in advance
  Stephen Mortensen
  PSN Station #55
  near Pilot Hill Ca
  38.828N  120.978W


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Larry Cochrane <cochrane@..............>