Benoit,

I think I may have replied to a message from Jim Lehman that he had meant=20
for you.

However, I can offer a couple of comments on your question.  The first=20
three designs are verticals, more like the LaCoste design than the=20
Lehman.  It's not clear what their sensitivity and frequency responses are,=
=20
but they look like they would be flat to velocity over a moderate frequency=
=20
range.  How wide a range would depend on how much damping they are getting=
=20
with their oil dampers.

The Volksmeter is a horizontal device, narrow-band to velocity centered at=
=20
1Hz and with an acceleration response flat from DC to 1Hz.

Whether a vertical or horizontal device is 'better' can be debated, but=20
they each have their own advantages and disadvantages.

Brett




At 09:52 PM 1/30/2008 -0500, you wrote:
>I am interested in acquiring a simple seismometer package for amateur use=
=20
>that is sensitive enough to detect teleseismic events. I would like to=20
>acquire a ready-to-use instrument rather than build something from scratch=
=20
>or from a kit. My main question is which seismometer to buy. I have come=20
>across the following instruments on the Web:
>
>AS-1  Amateur Seismologist (Jeff Batten)    $550 ???
>http://www.amateurseismologist.com
>
>Vertical School Seismometer     Ward=92s Natural Science    $500
>h=
ttp://www.wardsci.com/Product.asp_Q_cmss_E_seismometer_A_pn_E_IG0018602=20
>
>
>EQ-1    Next Generation Science      $600
>http://www.nex=
gensci.com/store/pc/viewPrd.asp?idproduct=3D1=20
>
>
>Volksmeter II   RLL Instruments (Zoltech)    $995 single channel, $1495=20
>dual channel
>(patented Symmetric Differential Capacitor (SDC) array sensor)
>http://www.rllinstruments.com
>
>In spite of the price difference, the Volksmeter seems interesting. As far=
=20
>as I an tell, it is based on recent technology that is different form the=
=20
>other three, which seem to be of the traditional Lehman type.
>
>Does anyone have any opinions or advice to give a rank beginner who has=20
>not been in a science classroom or lab in over 40 years?
>
>
>Regards,
>
>Beno=EEt Evans
>Qu=E9bec, Canada
>
>
>
>
>               My e-mail address above should be working, but if not
>you can always use my mail form at: http://bnordgren.org/contactB.html
>                            using your Web browser.

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